Patent Publication Number: US-2022211954-A1

Title: System and method for syringe fluid fill verification and image recognition of power injector system features

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a Continuation Application of U.S. application Ser. No. 16/577,364, filed Sep. 20, 2019, now U.S. Pat. No. 11,285,273, issued Mar. 29, 2022, which is Divisional Application of U.S. application Ser. No. 15/249,667, filed Aug. 29, 2016, now U.S. Pat. No. 10,420,902, issued Sep. 24, 2019 and which claims priority to U.S. Provisional Patent Application Ser. Nos. 62/211,462, entitled “System and Method for Syringe Fluid Fill Verification and Image Recognition of Power Injector System Features”, filed Aug. 28, 2015 and 62/259,824, entitled “System and Method for Syringe Fluid Fill Verification and Image Recognition of Power Injector System Features”, filed Nov. 25, 2015, the contents of each of which are incorporated herein by reference. 
    
    
     BACKGROUND OF THE DISCLOSURE 
     Field 
     The present disclosure relates to systems and methods for verifying that a syringe is filled with fluid and, in particular, for determining the presence of such fluid based on an illuminated pattern produced by electromagnetic radiation projected through a portion of the filled syringe. In other aspects, the present disclosure relates to systems and methods for identifying the various features and properties of the fluid within the syringe. 
     Description of Related Art 
     In many medical, diagnostic, and therapeutic procedures, a medical practitioner, such as a physician, injects a patient with a medical fluid. In recent years, a number of injector-actuated syringes and powered injectors for pressurized injection of fluids, such as contrast media (often referred to simply as “contrast”), medicaments, or saline, have been developed for use in imaging procedures such as angiography, computed tomography, ultrasound, and magnetic resonance imaging. In general, these powered injectors are designed to deliver a preset amount of contrast or other fluid at a preset flow rate. 
     One of the issues involved in the injection of fluids into a patient using such automated injector systems is the possibility that air may be present in the syringe or fluid delivery system prior to injection. This issue is of particular concern in injection procedures for contrast medium, which are frequently colorless or only tinted to a limited degree. Further, imaging procedures are often performed under relatively low light levels to facilitate reading of x-rays, computer display screens, and the like. Accordingly, the concern that air in the syringe will not be identified prior to the injection procedure is increased. It is, therefore, desirable to readily detect if the syringe has not been filled with the fluid or is only partially filled with fluid (i.e., the syringe contains an amount of air) prior to the attempted injection. 
     Some solutions have been previously provided, in which the presence of liquid is indicated by an alteration of shape of an indicator pattern on the barrel of the syringe, as discussed, for example, in U.S. Pat. No. 4,452,251 to Heilman and U.S. Pat. No. 5,254,101 to Trombley, III, each of which are incorporated by reference herein in their entireties. However, systems and methods are needed to further aid in indicating the presence of liquid when the syringe is viewed from a distance or to allow verification of a filled syringe at a glance. Automated systems for verifying that the syringe is fully filled and does not include any air are also desirable. 
     In addition, since most medical fluids used with power injectors are clear, it is very difficult for a technician to quickly and easily distinguish between the fluid and air present in a translucent syringe. Accordingly, a need exists for a system used with a fluid injection device that is capable of differentiating between air and different types of fluid. In addition, automated systems that can determine various properties of the fluid, for example by analyzing properties and/or changes of the interaction between electromagnetic radiation with the contents of the syringe, and communicating those properties to the user, for example via a display screen, are also desirable. 
     SUMMARY 
     The systems and methods discussed herein provide an indication to the operator of a fluid injector of the presence of liquid in a syringe when the syringe is viewed from a distance or to allow verification of a filled syringe at a glance. In addition, automated systems for verifying that the syringe is fully filled and does not include any air are also provided. Such systems allow for the differentiation between air and/or different types of fluids contained within a syringe of the fluid injector, thereby enhancing safety by preventing air injections as well as facilitating improved workflow by preventing technicians from mixing up the fluid types. Further, in certain aspects the system may determine one or more properties of the fluid within the syringe and/or the injection procedure. 
     According to one aspect of the present disclosure, provided is a syringe comprising: a syringe barrel comprising a proximal end and a distal end comprising an angled surface; and a plunger slideably disposed in the syringe barrel and configured to advance through the barrel to expel a fluid therefrom. The plunger comprises a transparent or translucent material configured to transmit electromagnetic radiation therethrough such that an illuminated identification pattern is formed at a predetermined portion of the distal end of the syringe barrel when the syringe is filled with the fluid. 
     In one aspect, the syringe barrel may be shaped such that when an interior volume of the syringe barrel is completely or partially filled with air, at least one property of the illuminated identification pattern is different compared to when the syringe is completely filled with the fluid. The at least one property may comprise at least one of presence of, size, shape, and brightness of the illuminated identification pattern. 
     In one aspect, the illuminated identification pattern may not be visible when a percentage of a volume of air present in the distal end of the syringe is greater than about 15% of the volume of the distal end of the syringe having the angled surface. In another aspect, the illuminated identification pattern may be visible to an observer or to a sensor when the syringe is viewed from a side, at a straight-on orientation, or a tilted forward or tilted backward orientation. The angled surface of the distal end of the syringe barrel may have an angle of about 30 degrees to 60 degrees relative to a longitudinal axis of the syringe. 
     In one aspect, the electromagnetic radiation source may comprise a light bulb, an LED bulb, a photon emitter, an infrared emitter, a laser, or ambient light. In another aspect, at least one reference line or marking may be formed on a distal end of the syringe barrel and extend around a circumference of the distal end of the syringe barrel. The at least one reference line or marking may be formed on the barrel of the syringe by at least one of printing, overmolding, and etching. In one aspect, a first reference line or marking of the at least one reference line or marking is configured to align with a first predetermined portion of the illuminated identification pattern if a first fluid is present within the syringe and a second reference line or marking is configured to align with a second predetermined portion of the illuminated identification pattern if a second fluid is present within the syringe. The at least one reference line or marking may be configured to align with a predetermined portion of the illuminated identification pattern if a first fluid is present within the syringe and may be configured to be positioned away from the illuminated identification pattern if a second fluid is present within the syringe. 
     According to another aspect of the present disclosure, provided is a system for indicating whether a syringe is ready for use in injecting a fluid therein into a patient. The system comprises: a syringe comprising a barrel comprising a distal end having an angled surface and defining an interior volume configured to receive the fluid; and an electromagnetic radiation source positioned to emit electromagnetic radiation through at least a portion of the syringe. The syringe is shaped such that, when the syringe is filled with the fluid, at least a portion of the electromagnetic radiation is affected by an interaction of the electromagnetic radiation with at least one interface associated with the fluid and the syringe to form an illuminated identification pattern indicative of contents of the syringe on a predetermined portion of the syringe. 
     In one aspect, the syringe may be shaped such that when the interior volume is completely or partially filled with air, at least one property of the illuminated identification pattern is different compared to when the interior volume is completely filled with the fluid. The at least one property may comprise at least one of presence of, size, shape, and brightness of the illuminated identification pattern. The illuminated identification pattern may not be visible when a percentage of a volume of air present in the distal end of the syringe is greater than about 15% of the volume of the distal end of the syringe having the angled surface. 
     In another aspect, the system may further include at least one sensor configured to measure the at least one property of the illuminated identification pattern when present. The at least one sensor may comprise at least one of an imaging sensor, an optical sensor, an electromagnetic radiation detector, or a digital camera. In another aspect, the system may also include a fluid injector configured to interface with the syringe to eject the fluid from the syringe. The fluid injector may comprise a controller configured to receive a confirmation signal from the at least one sensor when the measurement of the at least one property of the illuminated identification pattern indicates that the syringe is substantially filled with fluid, and the controller is configured to actuate the injector to perform an injection when the confirmation signal is received. 
     In one aspect, the illuminated identification pattern may be visible to an observer or to a sensor when the syringe is viewed from a side, at a straight-on orientation, or at a tilted forward or tilted backward orientation. In another aspect, the illuminated identification pattern may comprise an annular shape extending about at least a portion of the distal end of the syringe barrel. In yet another aspect, the angled surface of the distal end of the barrel may have an angle of about 30 degrees to 60 degrees relative to a longitudinal axis of the syringe. In one aspect, the electromagnetic radiation source may comprise a light bulb, an LED bulb, a photon emitter, an infrared emitter, a laser, or ambient light. 
     In certain aspects, the syringe may further comprise a plunger, and the electromagnetic radiation source is positioned to project at least a portion of the electromagnetic radiation to reflect off or transmit through the plunger. In one example, at least a portion of the plunger comprises a transparent or translucent material. In another example, at least a portion of the plunger comprises a colored material. 
     According to another aspect of the present disclosure, provided is a method for syringe fluid fill verification comprising: emitting electromagnetic radiation through at least a portion of a syringe; identifying whether at least a portion of the electromagnetic radiation produces an illuminated identification pattern on a predetermined portion of the syringe; and determining contents of the syringe based on at least one property of the illuminated identification pattern. 
     In one aspect, the at least one property may be at least one of a presence of the illuminated identification pattern, a size of the illuminated identification pattern, a shape of the illuminated identification pattern, and a brightness of the illuminated identification pattern. In another aspect, the step of: identifying whether the at least a portion of the electromagnetic radiation produces an illuminated identification pattern may comprise: measuring the at least one property of the illuminated identification pattern by at least one sensor associated with the syringe; and receiving a confirmation signal from the at least one sensor indicating a value for the at least one property of the illuminated identification pattern. In an additional aspect, emitting electromagnetic radiation through at least the portion of the syringe may comprises emitting electromagnetic radiation through a syringe plunger, at least a portion of which comprises a transparent or translucent material. 
     According to another aspect of the present disclosure, provided is a fluid injection system that comprises: a fluid injector; at least one syringe operatively engaged with the fluid injector; and an electromagnetic radiation source. The at least one syringe comprises a barrel comprising a distal end having an angled surface and defining an interior volume configured to receive a fluid. The electromagnetic radiation source is positioned relative to the at least one syringe to emit electromagnetic radiation through at least a portion of the at least one syringe such that, when the syringe is filled with the fluid, at least a portion of the electromagnetic radiation is affected by an interaction of the electromagnetic radiation with at least one interface associated with the fluid and the syringe to form an illuminated identification pattern indicative of contents of the at least one syringe on a predetermined portion of the at least one syringe. The fluid injection system also comprises: an image capture device positioned to capture an image of the illuminated identification pattern; and at least one computing device in communication with the image capture device and the fluid injector. The at least one computing device comprises at least one processor configured to: determine a distance from a bottom to a top of the illuminated identification pattern in the image of the illuminated identification pattern; compare the distance from the bottom to the top of the illuminated identification pattern to at least one predetermined distance; and based on the comparison of the distance from the bottom to the top of the illuminated identification pattern to the at least one predetermined distance, at least one of i) display on a display device in communication with the at least one processor an indication of a characteristic of the at least one syringe; ii) enable the fluid injector to perform a function; and iii) disable the fluid injector from performing an action. 
     In one aspect, determining a distance from the bottom to the top of the illuminated identification pattern may comprise determining a bottom edge of the illuminated identification pattern and determining a top edge of the illuminated identification pattern. The bottom edge and the top edge of the illuminated identification pattern may be determined by determining a change in contrast between neighboring pixels in the image of the illuminated identification pattern. 
     In another aspect, the characteristic of the at least one syringe may be the presence of air in the at least one syringe and the at least one processor may be further configured to, if the distance from the bottom to the top of the illuminated identification pattern is less than the at least one predetermined distance, provide an indication that air is present in the at least one syringe and disable the fluid injector from conducting an injection procedure. In addition, the at least one processor may be configured to determine a size of the at least one syringe prior to determining the distance from the bottom to the top of the illuminated identification pattern by matching a first template of a known illuminated identification pattern for a syringe having a first size with the image of the illuminated identification pattern. In one aspect, the at least one processor may be further configured to provide an indication that the at least one syringe has the first size if the first template matches the image of the illuminated identification pattern. The at least one processor may be further configured to match a second template of a known illuminated identification pattern for a syringe having a second size with the image of the illuminated identification pattern if the first template does not match the image of the illuminated identification pattern. The at least one processor may be further configured to provide an indication that the at least one syringe has the second size if the second template matches the image of the illuminated identification pattern. 
     In another aspect, the characteristic of the at least one syringe may be contents of the at least one syringe. The at least one predetermined distance may comprise a first predetermined distance indicative of a first fluid as the contents contained in the at least one syringe and a second predetermined distance indicative of a second fluid as the contents contained within the at least one syringe. If the distance from the bottom to the top of the illuminated identification pattern corresponds to the first predetermined distance, an indication that the first fluid is contained in the at least one syringe may be provided, and, if the distance from the bottom to the top of the illuminated identification pattern corresponds to the second predetermined distance, an indication that the second fluid is contained in the at least one syringe may be provided. If the at least one processor determines that the first fluid is present in the at least one syringe, a color of the electromagnetic radiation forming the illuminated identification pattern may be set to a first color and, if the at least one processor determines that the second fluid is present in the at least one syringe, the color of the electromagnetic radiation forming the illuminated identification pattern may be set to a second color different from the first color. 
     In other aspects, the at least one syringe may further comprise a plunger, and the electromagnetic radiation source may be positioned to project at least some of the electromagnetic radiation through the plunger. In such aspects, the plunger may comprise a transparent or translucent material. In still other aspects, the electromagnetic radiation source may be positioned such that the electromagnetic radiation reflects from a distal surface of the plunger through the barrel. In such aspects, the plunger may comprise an opaque, colored material. In other aspects, the electromagnetic radiation source may be positioned adjacent to the barrel of the at least one syringe and the electromagnetic radiation is reflected from a mirror located near the distal end of the barrel and directed toward a distal surface of the plunger such that the electromagnetic radiation reflects from the plunger through the barrel. 
     According to an additional aspect of the present disclosure, provided is a fluid injection system comprising: a fluid injector; at least one syringe operatively engaged with the fluid injector, the syringe comprising a barrel comprising a distal end having an angled surface and defining an interior volume configured to receive the fluid; an electromagnetic radiation source positioned relative to the at least one syringe to emit electromagnetic radiation through at least a portion of the at least one syringe such that, when the syringe is filled with the fluid, at least a portion of the electromagnetic radiation is affected by an interaction of the electromagnetic radiation with at least one interface associated with the fluid and the syringe to form an illuminated identification pattern indicative of contents of the at least one syringe on a predetermined portion of the at least one syringe; an image capture device positioned to capture an image of the illuminated identification pattern; and at least one computing device in communication with the fluid injector and the image capture device. The at least one computing device comprises at least one processor configured to: determine a distance from a bottom to a top of the illuminated identification pattern in the image of the illuminated identification pattern; compare the distance from the bottom to the top of the illuminated identification pattern to a predetermined distance; and if the distance from the bottom to the top of the illuminated identification pattern is less than the predetermined distance, provide an indication that air is present in the at least one syringe and disable the fluid injector from conducting an injection procedure. 
     In one aspect, determining a distance from the bottom to the top of the illuminated identification pattern may comprise determining a bottom edge of the illuminated identification pattern and determining a top edge of the illuminated identification pattern. The bottom edge and the top edge of the illuminated identification pattern may be determined by determining a change in contrast between neighboring pixels in the image of the illuminated identification pattern. 
     In another aspect, the at least one processor may be configured to determine a size of the at least one syringe prior to determining the distance from the bottom to the top of the illuminated identification pattern by matching a first template of a known illuminated identification pattern for a syringe having a first size with the image of the illuminated identification pattern. The at least one processor may be further configured to provide an indication that the at least one syringe has the first size if the first template matches the image of the illuminated identification pattern. The at least one processor may be further configured to match a second template of a known illuminated identification pattern for a syringe having a second size with the image of the illuminated identification pattern if the first template does not match the image of the illuminated identification pattern. The at least one processor may be further configured to provide an indication that the at least one syringe has the second size if the second template matches the image of the illuminated identification pattern. 
     According to another aspect of the present disclosure, provided is a fluid injection system that comprises: a fluid injector; at least one syringe operatively engaged with the fluid injector and configured to be illuminated with an electromagnetic radiation source to illuminate fluid contained therein; a sensor positioned to capture an image of the illuminated fluid; and at least one computing device in communication with the fluid injector and the sensor. The at least one computing device comprises at least one processor configured to: obtain from the sensor the image of the illuminated fluid; determine, based on the image of the illuminated fluid, at least one of: a type of the fluid contained within the at least one syringe; and whether air is contained within the at least one syringe; and automatically display on a display device in communication with the at least one processor one of: an indication of the type of the fluid contained within the at least one syringe; and an indication that air is contained within the at least one syringe. 
     In certain aspects, the at least one processor may be configured to disable the fluid injector from conducting an injection procedure if air is determined to be contained within the at least one syringe. Brightness measurements may be performed in a region of interest in the image of the illuminated fluid are utilized to determine at least one of: type of fluid contained within the at least one syringe; and whether air is contained within the at least one syringe. 
     According to another aspect of the present disclosure, provided is a fluid injection system comprising: a fluid injector; a syringe operatively engaged with the fluid injector; an image capture device; and at least one computing device in communication with the fluid injector and the image capture device. The syringe comprises a barrel and defining an interior volume and at least one feature provided on the barrel of the syringe. The at least one feature has a different appearance when viewed through different types of fluid contained within the syringe. The image capture device is positioned to capture an image of the at least one feature through a content of the syringe. The at least one computing device comprises at least one processor configured to: obtain the image of the at least one feature through the fluid contained within the syringe; determine, based on the image of the at least one feature, an appearance of the at least one feature; compare the determined appearance with templates of appearances of the at least one feature when viewed through different types of fluids; and automatically display on a display device in communication with the at least one processor an indication of a characteristic of the syringe based on the comparison. 
     In one aspect, the at least one feature may be formed on the barrel of the syringe by at least one of printing, overmolding, and etching. In another aspect, the at least one feature may be a fluid dot, a line, a series of lines, or any combination thereof. The appearance of the at least one feature may comprise at least one of a shape of the at least one feature and an orientation of the at least one feature. 
     In one aspect, the characteristic of the syringe may be the presence of air in the syringe and the at least one processor may be further configured to, if the determined appearance matches one of the templates of appearances of the at least one feature when viewed through air, provide an indication that air is present in the at least one syringe and disable the fluid injector from conducting an injection procedure. 
     In another aspect, the characteristic of the at least one syringe may be the contents of the at least one syringe and the at least one processor may be further configured to, if the determined appearance matches one of the templates of appearances of the at least one feature when viewed through a first fluid, provide an indication that the first fluid is present within the syringe. In one aspect, the at least one processor may be further configured to, if the determined appearance matches one of the templates of appearances of the at least one feature when viewed through a second fluid, provide an indication that the second fluid is present within the syringe. 
     According to another aspect of the present disclosure, provided is a fluid injection system comprising: a fluid injector; a syringe operatively engaged with the fluid injector in a vertical orientation, the syringe comprising a barrel and defining an interior volume configured to receive a fluid and at least one object having a density that is different than the density of the fluid such that the at least one object floats if the fluid is present within the barrel; an image capture device positioned to capture an image of the barrel; and at least one computing device in communication with the fluid injector and the image capture device. The at least one computing device comprises at least one processor configured to: obtain the image of the barrel; determine, based on the image of the barrel, a position of the at least one object within the barrel and thus whether the barrel is one of (i) filled completely with the fluid and (ii) filled at least partially with air; provide an indication, based on the determination, that air is present in the syringe based on the position of the at least one object; and disable the fluid injector from conducting an injection procedure. 
     According to still another aspect of the present disclosure, provided is a fluid injection system comprising: a fluid injector; a syringe operatively engaged with the fluid injector; an image capture device positioned to capture an image of at least a portion of the syringe; and at least one computing device in communication with the fluid injector and the image capture device. The at least one computing device comprises at least one processor configured to: obtain the image of at least a portion of the syringe; determine, based on at least a portion of the syringe, at least one characteristic of an injection procedure performed by the fluid injector; and adjust the at least one characteristic of the injection procedure performed by the fluid injector to ensure that fluid is delivered to a predetermined region of interest in a body of a patient at a particular time such that viable images are produced during an imaging procedure. 
     In one aspect, the at least one characteristic of the injection procedure may be at least one of flow rate, volume of fluid remaining within the syringe, and capacitance measurement of the syringe. 
     These and other features and characteristics of the systems and/or devices of the present disclosure, as well as the methods of operation and functions of the related elements of structures and the combination of parts and economies of manufacture, will become more apparent upon consideration of the following description and the appended claims with reference to the accompanying drawings, all of which form a part of this specification, wherein like reference numerals designate corresponding parts in the various figures. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limits of the systems and/or devices of the present disclosure. As used in the specification and claims, the singular form of “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic drawing of a fluid injector and fluid verification system, according to an aspect of the disclosure; 
         FIG. 2  is a schematic drawing of a syringe according to an aspect of the disclosure for use with the injector of  FIG. 1 ; 
         FIGS. 3A-3D  are schematic drawings of syringes having various shaped distal ends along with the appearance of an illuminated identification pattern, according to an aspect of the present disclosure; 
         FIGS. 4A-4C  are schematic drawings of syringes having various features provided on a distal end thereof to change shape and/or size of the illuminated identification pattern; 
         FIGS. 5A and 5B  are perspective and schematic views, respectively, of a syringe plunger that may be utilized with the syringe of  FIG. 2 ; 
         FIG. 6  is a schematic drawing of a syringe and fluid verification system including a backlit plunger, according to an aspect of the disclosure; 
         FIG. 7  is a schematic drawing of a syringe that is completely or partially filled with air in use with the fluid verification system of  FIG. 6 ; 
         FIG. 8  is a schematic drawing of a fluid filled syringe in use with the fluid verification system of  FIG. 6 ; 
         FIG. 9  is a schematic drawing of another example of a syringe and fluid verification system with a backlit plunger, according to an aspect of the disclosure; 
         FIG. 10  is a schematic drawing of a syringe and fluid verification system with a reflective plunger; 
         FIG. 11  is a schematic drawing of another embodiment of a syringe and fluid verification system with a reflective plunger; 
         FIG. 12  is a schematic drawing of another embodiment of a syringe and fluid verification system with a reflective plunger and fiber optic light pipe; 
         FIG. 13  is a schematic drawing showing light rays reflecting within and transmitting through a fluid filled syringe barrel according to an aspect of the disclosure; 
         FIGS. 14A-14C  are schematic drawings of portions of the distal end of embodiments of a fluid filled syringe for use with a fluid verification system, according to aspects of the disclosure; 
         FIG. 15A  is a side view of a rolling diaphragm syringe in accordance with one aspect of the present disclosure; 
         FIG. 15B  is a cross-sectional side view of the rolling diaphragm syringe shown in  FIG. 15A  taken along line A-A; 
         FIG. 16A  is a perspective view of a rolling diaphragm syringe and a pressure jacket in accordance with another aspect of the present disclosure; 
         FIG. 16B  is a cross-sectional side view of the rolling diaphragm syringe and the pressure jacket shown in  FIG. 16A ; 
         FIG. 16C  is a perspective view of a rolling diaphragm syringe and a cap for use with the pressure jacket shown in  FIG. 16A ; 
         FIGS. 17A and 17B  are a perspective cross-sectional view and cross-sectional view of the rolling diaphragm syringe and portions of an engagement mechanism illustrating a first configuration of an electromagnetic radiation source, according to an aspect of the disclosure; 
         FIGS. 18A and 18B  are perspective cross-sectional views of the rolling diaphragm syringe and portions of an engagement mechanism illustrating second and third configurations of an electromagnetic radiation source, according to aspects of the disclosure; 
         FIGS. 19A and 19B  are a perspective cross-sectional view and cross-sectional view of a rolling diaphragm syringe and portions of an engagement mechanism illustrating a third configuration of an electromagnetic radiation source, according to aspects of the disclosure; 
         FIG. 20  is a cross-sectional view of the rolling diaphragm syringe and portions of the engagement mechanism illustrating a protruding element, according to an aspect of the disclosure; 
         FIG. 21  is a flow chart of a method for determining presence of air within a syringe utilizing image processing techniques in accordance with an aspect of the present disclosure; 
         FIGS. 22 and 23  are drawings of exemplary images of a distal end of a syringe used in the method of  FIG. 21 ; 
         FIG. 24  is a graph illustrating the correlation between the presence of air and the size of the distance between the meniscus and the halo used in the method of  FIG. 21   
         FIG. 25  is a schematic drawing of an alternative syringe for use with the injector of  FIG. 1 ; 
         FIG. 26  is a flow chart of an alternative method for determining the presence of air within a syringe utilizing image processing techniques and the syringe of  FIG. 25  in accordance with an aspect of the present disclosure; 
         FIG. 27  is a drawing of an exemplary image of a distal end of a syringe containing air used in the method of  FIG. 26 ; 
         FIG. 28  is a drawing of an exemplary image used by an image recognition system to determine whether air is present within a syringe using brightness measurements in accordance with an aspect of the present disclosure; 
         FIGS. 29 and 30  are drawings of exemplary images used by an image recognition system to determine the type of fluid contained within a syringe in accordance with an aspect of the present disclosure; 
         FIGS. 31 and 32  are drawings of alternative exemplary images used by an image recognition system to determine the type of fluid contained within a syringe in accordance with an aspect of the present disclosure; 
         FIGS. 33 and 34  are drawings of exemplary images used by an image recognition system to determine the size of a syringe in accordance with aspects of the present disclosure; 
         FIGS. 35 and 36  are drawings of exemplary images used by an image recognition system to determine whether a fluid path set is connected to a syringe in accordance with an aspect of the present disclosure; 
         FIG. 37  is a perspective view of a fluid transfer system including a fluid transfer device for transferring fluid from a fluid container into a syringe in accordance with an aspect of the present disclosure; 
         FIGS. 38 and 39  are drawings of exemplary images used by an image recognition system to determine whether a fluid transfer device is connected to a syringe in accordance with an aspect of the present disclosure; 
         FIG. 40  is a perspective view of a purge container connected to a fluid transfer set in accordance with an aspect of the present disclosure; 
         FIG. 41  is a perspective view of the purge container of  FIG. 40 ; 
         FIG. 42A  is a front plan view of the purge container of  FIG. 40  with no fluid contained therein; 
         FIG. 42B  is a front plan view of the purge container of  FIG. 40  with fluid contained therein; 
         FIG. 43A  is a perspective view of an alternative configuration of the purge container of  FIG. 40  with no fluid contained therein; 
         FIG. 43B  is a front plan view of the purge container of  FIG. 43A  with fluid contained therein; 
         FIG. 44A  is a perspective view of another alternative configuration of the purge container of  FIG. 40  with no fluid contained therein; 
         FIG. 44B  is a front plan view of the purge container of  FIG. 44A  with fluid contained therein; 
         FIG. 45  is a perspective view of an example of a purge container connected to a fluid transfer set in accordance with an aspect of the present disclosure; 
         FIG. 46  is a front view of an end of tubing used with the fluid transfer set in accordance with an aspect of the present disclosure; 
         FIG. 47  is a schematic view of a syringe during an injection procedure illustrating the manner in which the syringe stretches and swells in accordance with an aspect of the present disclosure; 
         FIG. 48  is a graph illustrating volume delivered versus time during an exemplary injection procedure; 
         FIG. 49  is a flow chart of a method for determining the volume of fluid remaining within a syringe utilizing image processing techniques in accordance with an aspect of the present disclosure; 
         FIG. 50  is a perspective view of an alternative syringe for use with the system of  FIG. 1 ; 
         FIG. 51  is a side view of the syringe of  FIG. 50 ; 
         FIG. 52  is a schematic view of the syringe of  FIG. 50  delivering fluid at low pressure and a fluid verification system in accordance with aspects of the present disclosure; 
         FIG. 53  is a schematic view of the syringe of  FIG. 50  delivering fluid at high pressure and a fluid verification system in accordance with aspects of the present disclosure; 
         FIG. 54  is a schematic view of the syringe of  FIG. 50  drawing in fluid at negative pressure in accordance with an aspect of the present disclosure; 
         FIG. 55  is a schematic view of the syringe of  FIG. 15A  having a pressure indicating mechanism associated therewith in accordance with an aspect of the present disclosure; 
         FIG. 56A  is a schematic view of a syringe delivering fluid at low pressure and a fluid verification system in accordance with another aspect of the present disclosure; 
         FIG. 56B  is a schematic view of the syringe of  FIG. 56A  delivering fluid at high pressure and the fluid verification system; 
         FIG. 57  is a schematic view of a syringe having a temperature strip incorporated therewith in accordance with an aspect of the present disclosure; 
         FIG. 58  is a front perspective view of a fluid injection system in accordance with an aspect of the present disclosure; 
         FIG. 59  is a schematic view of the fluid injection system in accordance with an aspect of the present disclosure; 
         FIG. 60  is a schematic view of a portion of the fluid injector of the fluid injection system of  FIG. 59 ; 
         FIGS. 61-63  are schematic views of various configurations of the fluid injection system of  FIG. 59 ; 
         FIG. 64  is a schematic view of another alternative syringe for use with the system of  FIG. 1 ; 
         FIG. 65  is a schematic view of the syringe of  FIG. 64  filled with air and a fluid verification system in accordance with an aspect of the present disclosure; 
         FIG. 66  is a schematic view of the syringe of  FIG. 64  filled with saline and a fluid verification system in accordance with an aspect of the present disclosure; and 
         FIG. 67  is a schematic view of the syringe of  FIG. 64  filled with contrast and a fluid verification system in accordance with an aspect of the present disclosure. 
     
    
    
     DESCRIPTION 
     For purposes of the description herein, the terms “upper”, “lower”, “right”, “left”, “vertical”, “horizontal”, “top”, “bottom”, “lateral”, “longitudinal”, and derivatives thereof shall relate to the disclosure as it is oriented in the drawing figures. When used in relation to a syringe, the term “proximal” refers to the portion of a syringe nearest to an injector, when a syringe is connected to an injector. The term “distal” refers to the portion of a syringe farthest away from an injector. It is to be understood, however, that the disclosure may assume alternative variations and step sequences, except where expressly specified to the contrary. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification, are simply exemplary embodiments of the disclosure. Hence, specific dimensions and other physical characteristics related to the embodiments disclosed herein are not to be considered as limiting. 
     One aspect of the present disclosure is directed to a fluid injection system and a fluid verification system for confirming, using image processing techniques, that a syringe, containing a fluid for injection, is fully filled with fluid and neither has free space (i.e., air) near the distal end thereof when the syringe is provided in an upright position nor contains air bubbles. The present disclosure is also generally directed to using imaging processing techniques to determine various injection parameters to verify the type and certain properties of fluid that is present within a syringe. 
     As used herein, fluid and/or medical fluid refer to liquid substances or solutions, such as, but not limited to, contrast, saline, and therapeutic liquids. In certain aspects, the fluid verification system is configured to emit electromagnetic radiation, such as a visible or infrared light, through at least a portion of the syringe barrel. Electromagnetic radiation refers to radiant energy that propagates through space in the form of one or more electromagnetic waves. Electromagnetic radiation can be visible (e.g. having a wavelength of between approximately 400 nm to 700 nm) or non-visible to the human eye, as is the case, for example, with x-rays, radio rays, infrared radiation, and ultraviolet radiation. In addition, as used herein electromagnetic radiation may be ambient light. When the syringe is fully filled with a fluid, the electromagnetic radiation is refracted by the fluid and/or the syringe barrel to illuminate the distal end of the syringe to provide a distinctive identification pattern. The illuminated area defining the identification pattern on the distal end of the syringe is referred to herein as a halo. As used herein the term “halo” includes an illuminated identification pattern that includes a circular colored/illuminated ring around or a conical sub-portion of the distal portion of the conical distal end of the syringe. This halo may be readily identified by an operator when viewed at a straight-on, true side view, or slightly elevated position. In one example, this straight-on or true side view may be in a plane generally parallel to a plane extending through a central axis of the syringe and generally along a plane extending through a distal end of the syringe. Illuminating the syringe in the manner described herein may also cause any air bubbles present along the sidewalls of the syringe barrel to be illuminated, thereby allowing an operator or sensor to more easily identify the presence of such air bubbles. 
     In some aspects, one or more sensors may be configured to capture images of the distal end of the syringe, for example to detect the halo pattern via automated image processing techniques. If the syringe is entirely filled with fluid, a distinctly observable halo, for example in a form of a lighted band on at least a portion of the distal end of the syringe, is illuminated as an identification that the syringe is fully filled with fluid. If the syringe is not entirely filled with fluid, such as when the syringe is completely or partially filled with air, the size and/or brightness of the halo is substantially reduced or disappears. As used herein, fluid refers to a medical grade liquid configured to be delivered to a patient, such as saline or various types and concentrations of contrast, as opposed to air or other gases. 
     I. Generation of Illuminated Identification Pattern 
     A. Exemplary fluid Injection System 
     With reference to  FIG. 1 , a fluid injector  10 , such as an automated or powered fluid injector, is illustrated, which is adapted to interface with and actuate one or more syringes  12 , which may be filed with a fluid F, such as contrast media, saline solution, or any desired medical fluid. The fluid injector  10  can be used during an angiographic, computed tomography (CT), magnetic resonance imaging (MRI), molecular imaging, or other medical procedure to inject contrast and/or a common flushing agent, such as saline, into the body of a patient. In some examples, the fluid injector  10  can be at least a dual-syringe injector, wherein the two fluid delivery syringes  12  are oriented in a side-by-side or other spatial relationship and are separately actuated by respective linear actuators or piston elements associated with the injector  10 . 
     The injector  10  can be enclosed within a housing  14  formed from a suitable structural material, such as plastic and/or metal. The housing  14  can be formed in various shapes and sizes depending on the desired application. For example, the injector  10  can be a free-standing structure configured to be placed on the floor or may be configured for placement on a suitable table or support frame. The injector  10  includes one or more syringe ports  16  for connecting to the proximal ends of the one or more syringes  12  and to connect plungers  26  to respective piston elements. The syringe ports  16  are generally located on a side of the housing  14 , as shown, for example, in  FIG. 1 . The housing  14  can be rotatable to direct the syringe port  16  and syringe  12  extending therefrom in the vertical, horizontal, or downward facing direction. In some examples, the syringe  12  can include at least one identification tag  34 , such as a label or bar code, including information about the syringe dimensions, volume, pressure tolerances, and/or information about the fluid contained in the syringe  12 . The at least one identification tag  34  can be read by a sensor  36 , positioned on or recessed in the side of the housing  14  or within at least a portion of the inner surface of the at least one syringe port  16  of the injector  10 . 
     A fluid path set  17  can be interfaced with the syringe  12  for delivering one or more fluids from the syringe  12  to a catheter (not shown) inserted into a patient at a vascular access site. For example, a flow of saline solution from a first syringe  12  and contrast from a second syringe  12  may be regulated by a fluid control module (not shown) associated with the injector  10 . The fluid control module operably controls injection rates, pressures, valves and flow regulating structures, such as pistons or linear actuators, to regulate the delivery of the saline solution and/or contrast to the patient based on user selected injection parameters, such as injection flow rate, duration, total injection volume, and ratio of contrast media and saline, which may be programmed or otherwise entered into the injector fluid control module. 
     A suitable front-loading fluid injector for use with the above-described system is disclosed in U.S. Pat. No. 5,383,858 to Reilly et al., which is incorporated by reference in its entirety. Other exemplary multi-fluid delivery systems and components are found in U.S. Pat. No. 7,553,294 to Lazzaro et al.; U.S. Pat. Nos. 7,666,169 and 9,199,033 to Cowan et al.; U.S. Pat. No. 9,173,995 to Tucker et al.; PCT Publication No. WO 2012/155035 to Shearer et al.; and U.S. Patent Application Publication No. 2014/0027009 to Riley et al., all of which are assigned to the assignee of the present application, and the disclosures of which are incorporated herein by reference. 
     B. Exemplary Syringe for use with the Fluid Injection Device 
     1. Details of Syringe Body 
     Having described the general structure and function of the fluid injector  10 , a syringe  12  configured for connection to the injector  10  and containing a fluid F will now be discussed in detail. With reference to  FIG. 2 , the syringe  12  comprises a substantially cylindrical barrel  18  formed from glass or a suitable medical-grade plastic and defining an interior volume  19 . For example, the barrel  18  can be formed from medical grade polyethylene terephthalate (PET) or other medical-grade plastic material. The barrel  18  has a proximal end  20  and a tapered, conical distal end  24  extending to a nozzle  22 . The barrel  18  can be formed from a transparent or translucent material so that a user or system operator can observe fluid F contained therein and, as is discussed herein, when used with a fluid verification system, can identify the halo on the distal end  24  of the barrel  18 . In other examples, only the distal end  24  of the barrel  18  is transparent or translucent, and other portions of the barrel  18  are formed from an opaque reflective material for increasing transmission of light through the barrel  18 . In some aspects, a shield (not shown) may be provided around an outer circumference of the barrel  18 . The shield may be formed from an opaque reflective material for increasing the transmission of light through the barrel  18 . The fluid F generally has an index of refraction greater than that of air and may be different from the material of the barrel  18  and, therefore, alters the path of electromagnetic radiation, such as visible light, traveling through the barrel  18  of the syringe  12 . For example, the refractive index of air is about 1, the refractive index of saline is about 1.34, the refractive index of contrast is about 1.46, and the refractive index of PET is about 1.57. Without intending to be bound by theory, a travel path of electromagnetic radiation is governed by the reflection and refraction characteristics of the media through which electromagnetic radiation travels. 
     The appearance of an illuminated area or halo  120  is determined, at least in part, based on the angle and/or shape of the tapered distal end  24  of the barrel  18  as shown in  FIGS. 3A-3D . In some aspects, the tapered distal end  24  of the barrel  18  may be tapered at an angle ranging from 30 degrees to 60 degrees, and in other aspects from 40 degrees to 50 degrees relative to the horizontal or to a latitudinal or radial axis extending through the syringe  12 . In one example, the angle of the tapered distal end  24  of the barrel  18  is about 45 degrees relative to the horizontal (see  FIG. 3A ). There are also high and low thresholds where the reflected illuminated area or halo no longer becomes visible. Accordingly, changing the angle and/or shape of the tapered distal end  24  of the barrel  18  may have an impact on the size and visualization of the halo  120 . For example, as the angle of the tapered distal end  24  of the barrel increases, the size of the visualized halo increases (see  FIG. 3C  illustrating a syringe having a tapered distal end  24  with an angle of 60 degrees relative to the horizontal). However, the brightness of the halo generally decreases with such an increase of the angle. This may be compensated for by increasing the intensity of the electromagnetic radiation from the source used to generate the halo. In another example, as the angle of the tapered distal end  24  of the barrel  18  decreases, the size of the halo  120  also decreases as shown in  FIG. 3B . Finally, if the distal end  24  of the syringe does not have any angled surfaces, such as the dome shaped syringe shown in  FIG. 3D , no halo  120  is generated. The specific details of the manner in which the halo  120  is generated at the distal end of the syringe  12  are provided herein. 
     In some examples, at least a portion of the distal end  24  of the syringe barrel  18  can include one or more elements configured to accentuate the appearance of the halo  120 . The one or more elements may be in the form of scallops or ridges  24 A extending circumferentially around an outer surface of the distal end  24  of the barrel  18 . The scallops or ridges  24 A can be positioned to refract at least a portion of the halo  120 , making it visible over a range of viewing angles and user positions. The scallops or ridges  24 A can be used to make multi-part lenses such as a Fresnel lens. Lenses of this type can allow light passing through the portion of the syringe  12  where the halo  120  is visualized to be redirected into a more direct path toward a detector or viewer. Such lenses can also be used to transmit light over a farther distance and appear brighter at a larger number of viewing angles. Additionally, the scallops or ridges  24 A allow for enhanced visualization of the halo  120  or other features within the syringe  12 . The geometry of the ridges  24 A may be determined by the internal reflection of the light and the corresponding combination or convergence of rays back at the eye of the viewer. With reference to  FIGS. 4A-4C , different arrangements of the scallops or ridges  24 A at the distal end  24  leading to different shapes or sizes of the produced halo  120  are illustrated. 
     Returning to  FIG. 2 , in some examples, an annular flange, often referred to as a drip flange  28 , extends radially outward from the syringe barrel  18  at a position near the proximal end  20  thereof. When the syringe  12  is inserted in the injector  10  (shown in  FIG. 1 ), the drip flange  28  is positioned relative to a distal opening of the syringe port  16  (shown in  FIG. 1 ) to prevent excess fluid expelled from the syringe  12  from entering the port  16 . The portion of the syringe barrel  18  between the drip flange  28  and the proximal end  20  of the barrel  18 , referred to herein as the insertion portion  30 , is sized and adapted to be inserted in the syringe port  16  of the injector  10 . Accordingly, in some examples, the insertion portion  30  of the barrel  18  includes one or more locking structures, such as a locking flange  32 , extending radially outward from the barrel  18 . The locking flange  32  can be adapted to form a locking engagement with corresponding protrusions or locking structures in syringe port  16  for releasably maintaining syringe  12  in syringe port  16  while injector  10  is in use. Alternatively, insertion portion  30  can include one or more latches, locking mechanisms, or radially extending ribs for connection to corresponding portions of syringe port  16 . 
     Exemplary syringes suitable for use with the injector  10  depicted in  FIG. 1 , and which can be adopted for use with a fluid verification system, are described in U.S. Pat. No. 5,383,858 to Reilly et al.; U.S. Pat. Nos. 7,666,169 and 9,199,033 to Cowan et al.; and U.S. Pat. No. 9,173,995 to Tucker et al., which are assigned to the assignee of the present application. Additional exemplary syringes are disclosed in U.S. Pat. No. 6,322,535 to Hitchins et al. and U.S. Pat. No. 6,652,489 to Trocki et al., which are assigned to the assignee of the present application. The disclosures of each of these references are incorporated by reference in their entireties. 
     2. Examples of Plungers for use with Exemplary Syringe 
     With continued reference to  FIG. 2 , the proximal end  20  of the syringe barrel  18  can be sealed with a plunger or plunger cover  26  which is slidably disposed within the syringe barrel  18 . The plunger or plunger cover  26  may have a distal surface  26 A. The plunger or plunger cover  26  forms a liquid-tight seal against the sidewall of the barrel  18  as it is advanced or withdrawn therethrough. The plunger or plunger cover  26  can include an interior cavity  27  and proximal opening  29  configured to receive and engage a distal end of a piston rod (not shown) extending from the injector  10  (shown in  FIG. 1 ). The piston rod is advanced or retracted through the syringe barrel  18  by the injector  10  to drive the plunger or plunger cover  26  through the interior  19  of the syringe barrel  18  to expel fluid F therefrom or deliver fluid F into the syringe barrel  18 . 
     In some examples, the plunger or plunger cover  26  is at least partially formed from a substantially transparent or translucent material and configured to permit electromagnetic radiation, such as visible light, ambient light, infrared light, or ultraviolet light, to pass through or be emitted from a portion of the plunger or plunger cover  26 . For example, the plunger or plunger cover  26  can include a transparent or translucent central portion enclosed by an annular elastomeric ring that provides the seal between the plunger cover  26  and the inner surface of the barrel  18 . The emitted electromagnetic radiation radiates, propagates, or travels within and/or through the syringe barrel  18  in a substantially axial direction toward the distal end  24  of the syringe barrel  18 , while other electromagnetic radiation is emitted in a non-axial direction but at least a portion of the electromagnetic radiation is reflected off of the interior surface of the syringe barrel  18  toward the distal end  24 . It also propagates from the plunger or plunger cover  26  in a non-axial direction with a portion thereof reflecting off the sidewall of the syringe barrel  18  toward the distal end  24  of the syringe  12 . Electromagnetic radiation beams can be scattered when passing through the transparent or translucent material of the plunger or plunger cover  26 , which contributes to the appearance of the halo. While the plunger or plunger cover  26  can be clear, or tinted white, certain more noticeable colors can be useful in particular applications. For example, the plunger material can be tinted a conspicuous color, such as bright red or bright green, to impart a color to the halo. Imparting a bright, noticeable color to the halo assists the system operator in recognizing the halo, when present. For example, the plunger or plunger cover  26  can be tinted green or blue to increase visibility and as confirmation that the syringe  12  is ready for use (e.g., green is often understood to signify a “begin” or “go” state of readiness). Alternatively, the electromagnetic radiation passing through the plunger or plunger cover  26  may have a color, such as a red, green, blue, or other color from a light source to define a colored halo. 
     Alternatively, or in addition to including transparent or translucent portions, in other aspects the plunger or plunger cover  26  can include one or more windows or openings  31  that permit the electromagnetic radiation to pass therethrough. For example, the plunger or plunger cover  26  can include a pattern of windows positioned along portions of the cover  26  that contributes to formation of the halo. The windows or openings  31  can be covered by a transparent or translucent material or film to ensure that the plunger or plunger cover  26  is fluid tight. Other portions of the plunger or plunger cover  26  can be formed from an opaque material and, unlike in previously described examples, do not need to be capable of allowing light to pass through. In one example, selective lighting through these windows or openings  31  can be used to change patterns on the visible halo  120  or the color of the halo  120  based on certain system conditions or states. For example, some of the windows or openings  31  can be configured to have red light to emerge therethrough while other windows or openings  31  may be configured to have yellow light to emerge therethrough. Accordingly, the halo  120  may have a red color if only the red lights are turned on, a yellow color if only the yellow lights are turned on, or an orange color if all of the lights are turned. A certain color of the halo  120  may provide an indication of the operation of certain system conditions or states such as, but not limited to, the type of fluid being used, the size of the syringe, the volume of fluid in the syringe, the pressure within the syringe, the volume of fluid within the syringe, the presence of air within the syringe, etc. 
     In another example, the plunger or plunger cover  26  can be formed from or coated with a reflective or colored material rather than a translucent or transparent material. The reflective or colored material or surface reflects light directed toward the plunger or plunger cover  26  in the distal direction through the syringe barrel  18  to produce the halo. Exemplary fluid verification systems including a reflective plunger are illustrated in  FIGS. 10-12 , which are discussed herein in detail. 
     In yet another example, as shown in  FIGS. 5A and 5B , the plunger or plunger cover  26  can be formed from or coated with a reflective material having a plurality of different colored stripes  38 . The reflective material forming the stripes  38  reflects light directed toward the plunger or plunger cover  26  in the distal direction through the syringe barrel  18  to produce the halo. As the plunger or plunger cover  26  moves through the barrel, light reflects from a different stripe  38  depending on the position of the plunger or plunger cover  26  within the syringe barrel  18 . Since each of the stripes  38  of the plunger or plunger cover  26  are different in color, the color and/or appearance of the halo changes depending on the stripe  38  upon which the light is reflected as the plunger or plunger cover  26  advances or retracts through the syringe barrel  18  during an injection or filing procedure. A sensor, such as an image capture device, can be positioned to capture images of the halo as the plunger or plunger cover  26  advances or retracts through the syringe barrel  18  and detect the change in color of the halo. A processer operatively coupled to the sensor and suitably programmed can then be used to determine the volume remaining within the syringe based on the color/appearance of the halo. While the example shown in  FIGS. 5A and 5B  shows eight (8) different colored stripes, this is not to be construed as limiting the present invention as any suitable number of stripes may be utilized. Alternatively, a plunger or plunger cover  26  may be configured to emit different colors of light at specific portions of the syringe to produce a different colored halo depending on the volume of fluid remaining in the syringe. 
     Additionally, patterns other than colored stripes could be used to encode information into the plunger in a way that it is viewed in the halo  120 . One example of such a pattern is a barcode. In other aspects, symbols and/or words may be printed or applied to the plunger surface to be reflected to the halo portion and out to the user or image recognition means described herein. The process is similar to how a colored plunger creates a halo effect, however with symbols and/or letters in words, the reflection/refraction effect may slightly differ. For example, the syringe barrel represents a cylindrical lens with a focal point near the syringe tip. As an image approaches the focal point, the image may become distorted and stretched in ways which may make it unrecognizable. Additionally, the image may become inverted and difficult to read in the case of words. By controlling how the light reflects within the barrel, for example utilizing a Fresnel lens effect, the light hitting the plunger can be controlled to a point source which will focus on the letters regardless of plunger position. Thus, letters, words and/or symbols can be written on the plunger and then transmitted to the user through the halo only when the syringe is full of fluid. As described herein, no effect would be observed if the syringe contained significant amounts of air. In another aspect, symbols, words, and/or letters may be used to differentiate between saline and contrast in the syringe, as the letters or symbols written on the plunger will become distorted more significantly in contrast than in saline due to differences in the refractive index. 
     C. Generating an Illuminated Identification Pattern with the Exemplary Syringe 
     Having generally described various aspects the structure of the syringe  12  and plunger or plunger cover  26 , with reference to  FIG. 6 , components of one example of a fluid verification system  110  will be discussed in detail. The fluid verification system  110  includes an electromagnetic radiation source  112  for generating the radiation beam that forms a halo  120 . The electromagnetic radiation source  112  can be a light bulb, LED bulb, visible light emitter, infrared emitter, laser, other electromagnetic radiation sources, or ambient light provided to project an electromagnetic radiation beam through the interior  19  of the syringe  12 . In certain aspects, electromagnetic radiation source  112  emits electromagnetic radiation generally in an axial direction through syringe barrel  18  towards the distal end of the syringe. 
     1. Electromagnetic Radiation Source Positioned Beneath the Plunger 
     For example, as shown in  FIG. 6 , an electromagnetic radiation beam B passes through the translucent or transparent plunger or plunger cover  26  and toward the distal end  24  of the barrel  18 . The electromagnetic radiation source  112  can be configured to increase conspicuousness of the halo  120  or to tailor the halo  120  for particular sensors or electromagnetic radiation detectors. In one example, the electromagnetic radiation source  112  comprises a laser of a specific wavelength, for example in one embodiment having a wavelength of about 532 nm (e.g., a green laser). Lasers emitting electromagnetic radiation at other wavelengths within the visible region are also envisioned. The laser electromagnetic radiation source  112  can be used with neutral colored or transparent plungers and still produce a conspicuous colored halo  120 . In other examples, the electromagnetic radiation source  112  can emit electromagnetic radiation outside the visible spectrum provided that the system includes a sensor or camera capable of detecting radiation (e.g. the halo  120 ) within the emitted wavelength. In still other examples, the electromagnetic radiation source  112  can emit polarized light or certain wavelengths of filtered light, which can be more easily distinguished from ambient light. In other examples, electromagnetic radiation source  112  can be configured to emit pulses of light according to a predetermined and identifiable sequence, which can be identified by a system operator or automatically detected by a sensor. 
     With continued reference to  FIG. 6 , the electromagnetic radiation source  112  is disposed below the plunger or plunger cover  26  to backlight the plunger or plunger cover  26 . For example, LED bulbs or other electromagnetic radiation emitting devices can be mounted to a base portion of a syringe-receiving stand, a piston, an actuator, or the syringe port configured to receive the syringe  12  and positioned to emit an electromagnetic radiation beam, for example, in the axial direction through the syringe barrel  18 . Accordingly, in some examples, the electromagnetic radiation source  112  can be integrated with the injector  10  (shown in  FIG. 1 ). For example, the electromagnetic radiation source  112  can be positioned on the injector port  16  (shown in  FIG. 1 ), adjacent to the drip flange  28  of the syringe barrel  18 , or at some other convenient location on the injector adjacent to the syringe port. 
     In other examples, the fluid verification system  110  can be a standalone structure including a base or holder for receiving a syringe  12  to be tested. The electromagnetic radiation source  112 , such as the LED or standard light bulb, can be positioned on or adjacent to the base or holder. In that case, the syringe  12  is verified to ensure that it is properly filled with fluid F. After verification is completed, syringe  12  is removed from the base or holder and transferred to an injector, such as fluid injector  10 , for delivery of fluid F to the patient. 
     Electromagnetic radiation passing through the plunger or plunger cover  26  substantially radiates through the syringe barrel  18  to form the halo  120  when the syringe is filled with fluid. With specific reference to  FIG. 7 , when the syringe  12  is filled or partially filled with air, the electromagnetic radiation beams pass through the syringe barrel  18 , but do not form a distinctive illuminated portion or halo  120  near the distal end  24  thereof. In contrast, as shown in  FIG. 8 , when the syringe  12  is entirely filled with fluid F, the electromagnetic radiation beams are refracted by the fluid F and the syringe barrel walls, which produces a halo  120  near the distal end  24  of the syringe  12 . As discussed in greater detail in connection with the methods and steps for syringe verification herein, a system operator or automated image reading or optical device (e.g. sensor  114 ) can identify whether the halo  120  is present and, if present, is the correct shape and size. If the halo  120  is too small, not bright enough, or not present at all, this may indicate that the syringe is not filled with sufficient fluid or contains air, and the system operator can add additional fluid F to the syringe  12  for complete filling prior to injection into a patient. If a halo  120  having the correct size, shape, and brightness is identified, then verification that the syringe is filled with fluid is complete and the fluid contents of the syringe  12  are ready for administration to a patient. Accordingly, fluid verification system  110  provides a suitable visual indication of whether a syringe  12  is full of fluid or whether even a small amount of air is present in the syringe interior  19 . 
     In addition, as shown in  FIGS. 7 and 8 , a line  40  may be formed on a distal end  24  of the syringe barrel  18  and extend around a circumference of the distal end  24  of the syringe barrel  18 . The line  40  may be formed on the barrel  18  using any suitable method such as, but not limited to, printing, overmolding, and etching. The line  40  is configured to work in conjunction with the halo  120  to provide the operator with a quick, visual indication of the type of fluid within the syringe  12 . For example, the halo  120  will be different sizes depending on the type of fluid present within the syringe due to different properties of different fluids. Accordingly, the line  40  may be formed on the syringe  12  to align with a particular portion of the halo  120 , such as the bottom edge as shown in  FIG. 8 , when a first fluid is present within the syringe  12  and to align with a second predetermined portion of the halo  120 , such as a middle portion, if a second fluid is present within the syringe  12  or may be positioned away from the halo  120  if the second fluid is present within the syringe  12 . In this manner, the operator can quickly and easily visually determine the location of the line  40  in relation to the halo  120  and, based on this information, determine the type of fluid present within the syringe  12 . 
     With reference to  FIG. 9 , another example of a syringe  12  and fluid verification system  110 , including a backlight translucent or transparent plunger or plunger cover  26 , is illustrated. The syringe  12  is mounted to a syringe port  16  of an injector  10 . One or more electromagnetic radiation sources  112 , such as LEDs, are mounted to or embedded in a distal end of a piston rod  124  of the injector  10 . When actuated, the piston rod  124  advances toward and is received within the cavity  27  defined by the plunger or plunger cover  26 . The LEDs emit light in the axial direction through the plunger cover  26  for producing the halo  120  adjacent to the distal end  24  of the syringe barrel  18  in the manner discussed above. The halo  120  can be identified by the sensor  114  positioned adjacent to the distal end  24  of the syringe barrel  18 . 
     2. Electromagnetic Radiation Source positioned so that Radiation Reflects from the Surface of the Plunger 
     With reference to  FIG. 10 , the radiation source  112  can also be arranged or positioned so that energy or electromagnetic radiation reflects from a distal surface  26 A of the plunger or plunger cover  26  axially through the syringe barrel  18  to form the halo  120 . For example, an electromagnetic radiation source  112 , such as described herein, could be positioned outside the barrel, for example, near the distal end  24  of the barrel  18  to project an electromagnetic radiation or light beam B toward the distal surface  26 A of the plunger or plunger cover  26  through the syringe barrel  18 . The electromagnetic radiation or light beam B then reflects off the plunger or plunger cover  26  in the distal direction with concomitant refraction/reflection by the fluid and/or syringe wall material to form a visible halo at the distal end of the syringe. 
     3. Electromagnetic Radiation Source positioned adjacent to the Surface of the Injector 
     In another example, as shown in  FIG. 11 , the system  110  can include an electromagnetic radiation source  112  positioned adjacent to the surface of the injector  10  and/or syringe port  16  (shown in  FIG. 1 ). The electromagnetic radiation source  112 , such as described herein, can be configured to focus and reflect a light or radiation beam B from a mirror  122  or other reflective element located near the distal end  24  of the syringe barrel  18 . The mirror  122  directs the light or electromagnetic radiation beam toward the distal surface  26 A of the plunger or plunger cover  26 , so that the radiation or light can reflect from the plunger or plunger cover  26  to form the halo  120  when the syringe is filled with fluid. The halo  120  can be identified visually by the operator or by the detector or sensor  114 . 
     4. Electromagnetic Radiation source including Fiber Optics 
     With reference to  FIG. 12 , in another example, a fiber optic light pipe  126  is used to provide light or electromagnetic radiation from an electromagnetic radiation source  112  toward the distal end  24  of the barrel  18 , for example wherein the source is associated with the injector body, and to shine or direct the light toward the distal surface  26 A of the plunger or plunger cover  26 . In one example, the light pipe  126  can be embedded in the syringe barrel  18  itself. Alternatively, the light pipe  126  may be embedded in a pressure jacket surrounding the syringe barrel  18 . In that case, light can be directed from the electromagnetic radiation source  112  located, for example, in the syringe port  16  of the injector  10  through the light pipe  126  toward the distal end  24  of the barrel  18 . Light emitted from the light pipe  126  is shown or directed toward the distal surface  26 A of the plunger or plunger cover  26  as shown by the light beam B, and permitted to reflect therefrom in the manner discussed in connection with the examples illustrated in  FIGS. 10 and 11  to form a halo at the distal end of the syringe when the syringe is filled with fluid. 
     5. The Illuminated Identification Pattern or Halo 
     With reference to  FIG. 13 , details of how electromagnetic radiation is refracted by fluid F and/or the material in the wall of barrel  18  to produce the halo  120  will be discussed in detail. As shown in  FIG. 13 , light rays, denoted generally as  130 , which are scattered in multiple orientations when passing through the plunger or plunger cover  26  (shown in  FIGS. 6 and 9 ), travel generally in the axial direction A toward the distal end  24  of the syringe barrel  18 . Some of the light rays  130  exit the syringe barrel  18  through the transparent or translucent sidewall of the syringe barrel  18 , meaning that the illuminated plunger  26  is visible to an observer  200 . Some light rays  130  reach the tapered, conical distal end  24  of the barrel  18  directly without contacting the sidewall of the barrel  18 . Light rays  130  shining directly on the distal end  24  of the barrel  18  would be visible to an observer  200  looking at a top of the syringe  12  from an elevated position. Some light rays  130  are focused to the distal end  24  of the syringe barrel  18  by total or partial internal reflectance, shown at reference number  132 , from the syringe barrel  18 . For example, light rays  130  directed to one side of the tapered, conical distal end  24  of the syringe barrel  18  are reflected by total internal reflectance, as shown at number  133 , toward the opposite side of the tapered distal end  24  when the syringe is filled with fluid and the difference in refractive index between the fluid, the syringe wall material and the air outside the syringe are different to cause internal reflection. If the syringe barrel  18  is filled completely with air or only partially filled with fluid F, the light rays  130  are not sufficiently internally reflected or focused to the distal conical end and would be only faintly visible, if at all, to an observer  200  over the area of syringe  12  filled with air. Without intending to be limited by any theory, it is believed that a large percentage of the light rays travelling through the volume of the syringe containing air are not internally reflected at the syringe barrel wall and, instead, exit the syringe through the sidewall; and since there is no substantial internal reflection, the light rays are not focused to the distal end of the syringe to produce an observable halo. In particular, focused light rays  130  would not be visible as a halo when looking at the syringe barrel  18  from a straight-on position or true side view when air is in the syringe. Thus, the halo  120  does not appear to be present when the syringe barrel  18  is not fully filled with fluid. 
     However, as shown in  FIG. 13 , when the syringe  12  is filled with fluid F, the light rays  130  reflected toward and focused to the tapered distal end  24  of the barrel  18  are refracted, as shown at line  131 , due to the difference in refractive index of the fluid relative to the outside air and the syringe wall material. Specifically, as discussed herein, air has a refractive index of substantially 1. In comparison, the refractive index of saline is about 1.34, the refractive index of contrast is about 1.46, and the refractive index of PET is about 1.57. The refracted light beams  130  exiting the syringe barrel  18  are viewable to an observer  200  at a lower angle compared to when the syringe barrel  18  is only partially filled with the fluid F. Further, due to the refraction, the light rays  130  may be further focused to increase the intensity of the light halo observed by the observer  200 . Accordingly, when looking at the fluid filled syringe  12  at a straight-on, true side view, or slightly elevated position, the observer  200  sees the illuminated halo  120  which has a distinctive appearance. 
     The structure and geometries of the syringe  12  and particularly the tapered, conical distal end are chosen to ensure that the halo  120  is easily visible at a predetermined portion of the barrel  18  (i.e., the distal end  24 ) from a particular set of positions or orientations. For example, in some embodiments, the injector  10  holds the syringe  12  at a tilted orientation (e.g., either leaning upwards or downwards from between about 0 to about 30 degrees relative to plane of the injector). To account for the tilted orientation of the syringe  12 , the shape of the barrel  18  and distal end  24  of the barrel  18  can be selected to increase visibility of the halo  120  when viewed in a tilted position. If the syringe  12  is held in a substantially straight (e.g., not tilted) position by the injector  10 , then the syringe  12  is shaped so that the halo  120  can be easily seen when the syringe  12  is viewed from a straight-on or true side view orientation. 
     More specifically, with reference to  FIG. 14A , if the syringe  12  is oriented such that it is generally viewed from a straight-on or tilted back (e.g., from 10 degrees to 30 degrees tilt) orientation, the angle  23  of the tapered distal end  24  of the barrel  18  is from about 30 degrees to 60 degrees, and in certain embodiments about 45 degrees relative to the horizontal. An angle of about 45 degrees creates a halo  120  that may be more easily seen than at a straight-on view angle. In particular, as shown in  FIG. 14A , the observer  200  can see the light rays  130  that form the halo  120  at a rather low orientation. 
     In contrast, as shown in  FIG. 14B , for a syringe  12  having a distal end  24  with a steeper angle  23 , the halo  120  is visible to the observer  200  at a higher (e.g., downward looking) orientation. If the syringe  12  is expected to be viewed in a tilted forward position, the higher viewpoint may be appropriate. In some examples, the distal end  24  of the barrel  18  can also have a dome shape. However, in most circumstances, the halo  120  may be easier to see through a tapered distal end  24  rather than a dome shaped distal end  24 . 
     In another example, as shown in  FIG. 14C , the distal end of the syringe  12  includes a distal portion  24  that includes a curved and angled portion extending from the barrel  18  to the nozzle  22  or tip. The distal portion  24  having such a curved and angled portion produces a halo  120  that can be seen from a wider range of viewing angles. In particular, as shown in  FIG. 14C , the light beams  130  can be seen by the observer  200  at either the straight-on orientation or a more downwardly directed orientation. Accordingly, for a syringe  12  having a distal portion  24  as shown in  FIG. 14C , the halo  120  is visible regardless of whether the injector  10  holds the syringe  12  in a slightly tilted or straight position. 
     6. Operation of Fluid Injection System with the Exemplary Syringe 
     With reference again to  FIGS. 1, 2, and 6 , in use, an operator inserts the proximal end  20  of the barrel  18  into a corresponding syringe port  16 . The operator may be required to exert some force against each syringe  12  so that the locking flange  32  of the syringe  12  engages with corresponding locking structures (not shown) of the syringe port  16  to form a suitable connection therewith. In certain examples, the operator continues to press the syringe  12  into the port  16  until the insertion portion  30  of the syringe barrel  18  is entirely inserted. In some cases an audible or tactile signal, such as a click, indicates that the syringe barrel is fully inserted, locked, and ready for use. 
     The syringe  12  may be preloaded with a fluid F. Alternatively, the injector  10  can automatically or manually draw fluid F into the syringe barrel  18  from an external fluid source. Once the syringe  12  is inserted in the port  16  and filled with fluid F, the electromagnetic radiation source  112  is turned on causing light beams to project through the plunger or plunger cover  26 . Alternatively, as discussed herein in connection with the exemplary systems illustrated in  FIGS. 10-12 , electromagnetic radiation or light can be directed toward the distal surface  26 A of the plunger cover  26  and reflected therefrom in the axial direction. In some examples, syringe insertion and halo identification can be coordinated such that the electromagnetic radiation source  112  turns on automatically each time that a syringe  12  is loaded into the injector  10 . Alternatively, the system operator can manually turn on the electromagnetic radiation source  112  by, for example, inputting a command through the user interface or pressing an activation button. Once the electromagnetic radiation source  112  is activated, the presence or absence of the illuminated portion or halo  120  (shown in  FIGS. 6 and 9 ) can be identified and/or detected, either by the technician or automatically by the sensor. Specifically, if the syringe  12  is fully filled with the fluid F, the halo  120  appears. If the syringe  12  is filled with air or only partially filled with fluid, then the halo  120  is either less pronounced or entirely absent. For example, the halo  120  begins to become less pronounced (i.e., smaller in size and/or less bright) as soon as air is introduced into the syringe and continues to fade until it is entirely absent when about 5 mL of air is present in a syringe  12  of the distal end of the syringe when a syringe such as the syringe shown in  FIG. 2  is utilized in the system. In other examples, the halo  120  is not visible when a percentage of a volume of air present in the distal end  24  of the syringe  12  is greater than about 15% of the volume of the conical shaped distal end  24  of the syringe  12 . In still other examples, the halo  120  is not visible when a percentage of a volume of air present in the distal end  24  of the syringe  12  is greater than about 10% of the volume of the conical shaped distal end  24  of the syringe  12 , and in yet other examples, the halo  120  is not visible when a percentage of a volume of air present in the distal end  24  of the syringe  12  is greater than about 20% of the volume of the conical shaped distal end  24  of the syringe  12 . In some examples, the system operator manually confirms, such as by visual verification, that the halo  120  is present before actuating the injector  10 . 
     Alternatively, according to another aspect of the present disclosure, the illuminated halo  120  can be detected automatically by one or more sensors  114 , such as a digital camera. More specifically, an image or images of the distal end  24  of the barrel  18  may be obtained by the one or more sensors  114 . The obtained image can be analyzed by a processor using image processing techniques (as will be discussed in greater detail herein). For example and as will be discussed in detail herein, pattern recognition algorithms can be used to identify an expected structure and other properties of the syringe  12 , fluid fill volume, fluid properties, and shape and/or location of the halo  120 , among other properties and features. The pattern recognition can also be used to identify information about the syringe  12 , such as syringe fluid volume or preferred injection parameters for a particular syringe size and geometry. Edge to edge distance calculating algorithms can be used to identify the position and length of the halo  120 . Edge to edge distance calculating algorithms can also be used to determine a length of the meniscus formed by the fluid F contained in the syringe  12 . Recognition of the meniscus position and size can be used to determine the fluid volume contained in the syringe  12  and free space (i.e. air volume), if any, between the meniscus and syringe nozzle. Brightness determining algorithms can be used to determine the intensity of the halo  120 . As previously discussed, the brightness of the halo  120  may be used as an indicator of an amount of air present in the syringe  12 . Accordingly, the processing algorithm could ensure that the halo brightness exceeds certain predetermined threshold values thus indicating that threshold amounts of air in the syringe are not exceeded. 
     In some examples, the injector  10  can be configured to “unlock/lock” based on whether the halo  120  is identified. For example, if the halo  120  is not identified, the injector  10  could enter a “locked” state preventing an injection from proceeding and/or request that the tested syringe be replaced with a new one. If the halo  120  is identified, the injector  10  may “unlock” and allow the operator to access other features of the user interface of the injector  10  and allow the injection procedure to proceed. Similarly, the injector  10  can be configured to cancel or halt a scheduled injection procedure if the sensor  114  fails to identify the halo  120  or if the halo  120  is identified but is not of sufficient brightness. If the halo  120  is present, the injector  10  can be configured to automatically begin the injection procedure. Activating the injector  10  causes the linear actuator to advance the piston rod  124  in the distal direction to contact and engage the plunger or plunger cover  26 . Advancing the plunger or plunger cover  26  in the distal direction through the barrel  18  expels fluid F from the syringe  12 , thereby injecting fluid F into the patient through any known injection structure, such as an IV tube or needle accessory. 
     D. Alternative Exemplary Syringe for use with Fluid Injection System 
     1. Structure of Alternative Exemplary Syringe 
       FIGS. 15A and 15B  illustrate an alternative exemplary syringe that may be utilized with fluid injector  10 . More specifically, these figures illustrate a rolling diaphragm syringe  135  in accordance with another aspect of the present disclosure. Various features of a rolling diaphragm syringe are described in detail in International PCT Application Publication No. WO 2015/164783, the disclosure of which is incorporated by this reference.  FIG. 15B  is a cross-sectional side view the rolling diaphragm syringe  135  shown in  FIG. 15A  taken along line A-A. Referring initially to  FIG. 15A , the rolling diaphragm syringe  135  generally includes a hollow body that includes a forward or distal end  137 , a rearward or proximal end  139 , and a flexible sidewall  134  extending therebetween. The sidewall  134  of the rolling diaphragm syringe  135  defines a soft, pliable or flexible, yet self-supporting body that is configured to roll upon itself, as a “rolling diaphragm”, under the action of a piston  138  (shown in  FIGS. 18A and 18B ) of the fluid injection  10 . In particular, the sidewall  134  of the rolling diaphragm syringe  135  is configured to roll such that its outer surface is folded and inverted in a radially inward direction as the piston  138  is moved in a distal direction and unroll and unfold in the opposite manner in a radially outward direction as the piston  138 , for example a piston releasably attached to a proximal end of an end wall  136  of the rolling diaphragm syringe  135 , is retracted in a proximal direction. 
     The rolling diaphragm syringe  135  may be made of any suitable medical-grade plastic or polymeric material. In various aspects, the clear plastic material may withstand sterilization procedures, such as exposure to ethylene oxide or electromagnetic radiation sterilization procedures. 
     With reference to  FIG. 15B  and with continued reference to  FIG. 15A , the distal end  137  of the rolling diaphragm syringe  135  has an open-ended discharge neck  140  having a connection member  140   a  for connecting to a corresponding connection member, for example the cap of  FIG. 17  as described herein, which may connect to a fluid path set (not shown). The discharge neck  140  has a first sidewall thickness T 1  that is greater than a thickness T 2  of a sidewall  134 . Thickness T 1  is selected such that the discharge neck  140  may be sufficiently rigid to allow for connecting to a corresponding connection member of a fluid path set (not shown) without substantially deforming the discharge neck  140 , for example during an injection procedure. Thickness T 2  is selected such that the sidewall  134  of the rolling diaphragm syringe  135  is flexible to allow for rolling over and unrolling of the sidewall  134  as described herein. The proximal end  139  of the rolling diaphragm syringe  135 , such as closed end wall  136 , may be reinforced to prevent deformation during rolling over, or in particular aspects, unrolling of the sidewall  134 . In some aspects, the proximal end  139  of the rolling diaphragm syringe  135  is configured for engagement with the piston  138 . 
     The end wall  136  may have a central portion  276  having a substantially dome-shaped structure and a piston engagement portion  244  extending proximally from the central portion  276 , such as an approximate midpoint of the central portion  276 . In some aspects, a distal most end of the central portion  276  may be substantially flat. The piston engagement portion  244  is configured for engagement with the engagement mechanism on the piston  138  of the fluid injector  10 . The proximal end  139  of the rolling diaphragm syringe  135  may have one or more ribs  278  protruding radially outward from the piston engagement portion  244  along a proximal surface of a ramp  272 . 
       FIG. 16A  is a perspective view of a syringe assembly  204  having a rolling diaphragm syringe  135  (shown in  FIG. 16B ) and a pressure jacket  210  in accordance with the present disclosure. The syringe assembly  204  includes the pressure jacket  210  that removably interfaces with the injector  10  (shown in  FIG. 1 ), as described herein. The pressure jacket  210  has a distal end  216 , a proximal end  218 , and a sidewall  219  extending between the distal end  216  and the proximal end  218  along a longitudinal axis of the pressure jacket  210  to define an internal throughbore  221  (shown in  FIG. 16B ). In some aspects, the sidewall  219  of the pressure jacket  210  is shaped to receive at least a portion of the rolling diaphragm syringe  135  (shown in  FIG. 16B ) within the throughbore  221 . The sidewall  219  of the pressure jacket  210  has a first distal portion  360   a  for receiving at least a portion of the rolling diaphragm syringe  135 , and a second proximal portion  360   b  for interfacing with the injector  10 . The first distal portion  360   a  may have an open end configured to releasably receive a cap  390  that encloses the interior of the pressure jacket  210 . The second proximal portion  360   b  may have an open end to allow the piston  138  of the fluid injector  10  to extend through the open end and engage rolling diaphragm syringe  135  held within throughbore  221 . The rolling diaphragm syringe  135  may be inserted through the open end of the first distal portion  360   a  or the second proximal portion  360   b.    
     In some aspects, the second proximal portion  360   b  has a locking lug or lip  370  protruding radially outward from an outer surface of the second proximal portion  360   b.  The locking lug or lip  370  may extend continuously or discontinuously around an outer circumference of the second proximal portion  360   b.  The locking lug or lip  370  is configured for interacting with corresponding features on the fluid injector  10  to releasably lock the pressure jacket  210  with the fluid injector  10 . In some aspects, the locking lug or lip  370  may have a connection member to releasably secure the pressure jacket  210  to a corresponding locking mechanism of the fluid injector  10  described in U.S. Pat. Nos. 5,383,858; 5,873,861; 6,652,489; 9,173,995; and 9,199,033. Other connection members between the pressure jacket  210  and the fluid injector  10  are described in International Application No. PCT/US2015/057751, filed Oct. 28, 2015, or International Application No. PCT/US2015/057747, filed Oct. 28, 2015, which are hereby incorporated by reference. 
     With reference to  FIG. 16B  and with continued reference to  FIG. 16A , the pressure jacket  210  may have a cap  390  that is releasably secured to the distal end  216 . In some aspects, the cap  390  may be secured by a threaded engagement, a bayonet fitting, or another mechanical fastening arrangement with the distal end  216  of the pressure jacket  210 . For example, as shown in  FIGS. 16B and 16C , the cap  390  may have at least one projection  430  that is received inside at least one groove  440  on the pressure jacket  210  such that the cap  390  may be locked with the pressure jacket  210  by aligning the at least one projection  430  to fit within the groove  440 . The cap  390  may have an inner element  400  with a nozzle  410 . The nozzle  410  may be in fluid communication with the interior volume of the rolling diaphragm syringe  135  (or directly formed on the rolling diaphragm syringe  135 ) to deliver fluid into or from the rolling diaphragm syringe  135 . The nozzle  410  may have a connection member  420  for removably connecting to a connector of fluid path set  17  (shown in  FIG. 1 ). 
     The annular sidewall  460  may have one or more gripping elements  470  (shown in  FIG. 16C ) to facilitate gripping of the cap  390  when the cap  390  is connected to and/or disconnected from the pressure jacket  210 . The cap  390  may have a radial flange  480  that extends radially outward from a proximal portion of the annular sidewall  460 . 
     With reference to  FIG. 16C , at least a portion of the rolling diaphragm syringe  135  may be removably secured to the cap  390 . In some aspects, the cap  390  may have a connection member that corresponds to and connects with the connection member  140   a  (shown in  FIG. 15A ) of the rolling diaphragm syringe  135 . As further shown in  FIG. 16C , the rolling diaphragm syringe  135  may initially be in a compressed configuration where the rolling diaphragm syringe  135  is rolled over on itself. Providing the rolling diaphragm syringe  135  in an initial compressed configuration may provide economic benefits during packaging and shipping by requiring less packaging material per syringe set up and/or allowing more syringe set-ups to be packaged. 
     2. Generating an Illuminated Identification Pattern with the Alternative Exemplary Syringe 
     Having generally described the structure of the rolling diaphragm syringe  135 , systems for generating an illuminated identification pattern with the rolling diaphragm syringe  135  to determine a fill status of the rolling diaphragm syringe  135  will be discussed in detail. In one example, with reference to  FIGS. 17A and 17B , the piston  138  of the fluid injector  10  may have one or more electromagnetic radiation sources  212 , such as LEDs, mounted to or embedded in a distal end thereof. When actuated, the piston  138  advances toward and engages the piston engagement portion  244  of the rolling diaphragm syringe  135 . The LEDs emit light in the axial direction through the piston engagement portion  244  for producing an illuminated identification pattern at a distal end  137  of the rolling diaphragm syringe  135 . 
     The wavelength of the electromagnetic radiation of the LEDs is chosen to match the material used to form the rolling diaphragm syringe to allow for the best transfer of energy. For example, the windows of a car are created from a material that prevents UV light from passing through to prevent sunburns while driving. The same principle holds true in the present application. The wavelength of the LEDs may be chosen to match the material used to manufacture the syringe to ensure maximum transmittance through the material of the piston engagement portion  244  and/or the wall thickness of syringe. Alternatively, instead of choosing the wavelength to match the material, a wavelength for the LEDs may be chosen that is the most visible to the human eye when combined with the halo effect described herein. For example, green light lies in the middle of the visible spectrum (approximately 532 nm) allowing light having such a wavelength to be readily visible to a technician. Also, depending on the solute concentration of the fluid contained within the syringe, along with the compounds present and their chemical properties, wavelengths for the LEDs can be selected to be selectively absorbed or transmitted by the fluid or having the desired reflection/dispersion properties. Accordingly, a wavelength of LEDs may be selected such that the light produced by the LEDs is dispersed by the fluid and generates more light therein, or the light may be absorbed/transmitted by the fluid and passes through similar to how the halo  120  is formed as described herein. 
     In other examples, the electromagnetic radiation source may be positioned in a variety of other locations such as, but not limited to, the piston engagement portion  244  of the rolling diaphragm syringe  135 , the pressure jacket  210 , external of the fluid injector  10  similar to the arrangement shown in  FIGS. 10 and 11 , a heat maintainer associated with the pressure jacket  210 , or any other suitable location. In one example, with reference to  FIGS. 18A and 18B , the electromagnetic radiation sources  212  may be positioned within another portion of the fluid injector, such as a clamp  213  positioned at the distal end of the syringe  135  used to secure the syringe  135  within the fluid injector. For instance, with reference to  FIG. 18A , the electromagnetic radiation sources  212  may be positioned around a circumference of the side of the clamp  213  to direct light through the sides of the pressure jacket  210  to the syringe  135 . Alternatively, with reference to  FIG. 18B , the electromagnetic radiation sources  212  may be positioned on a top surface of the clamp  213  to direct light down through the syringe  135 . 
     In one example, an end of the piston engagement portion  244  may be configured to expose the LEDs of the piston  138  when the piston  138  engages the piston engagement portion  244 . More particularly, the piston engagement portion  244  may be configured to disengage a cover (not shown) to expose the LEDs when the piston  138  engages the piston engagement portion  244 . 
     The piston engagement portion  244  of the rolling diaphragm syringe  135  may be shaped in a manner to collect light from the LEDs and direct light through the interior volume  214  of the rolling diaphragm syringe  135  towards the distal end thereof. For instance, the piston engagement portion  244  may have a convex lens shaped portion such that the portion focuses the light produced by the electromagnetic radiation sources  212  and directs the light up the piston engagement portion  244 . In addition, if the light sources of the electromagnetic radiation sources are collimated, then the shape of certain portions of the piston engagement portion  244  may be flat or any other suitable geometrical shape. 
     The piston engagement portion  244  may also have a textured surface to enhance the light collecting and transmission capabilities thereof. In addition, the central portion  276  of the end wall  136  may also include a textured surface to enhance the transmission of light to the distal end  137  of the rolling diaphragm syringe  135  when the rolling diaphragm syringe  135  is filled with fluid, and diffuse light when the rolling diaphragm syringe  135  is filled with air or partially filled with air. Alternatively, central portion  276  of end wall  136  may be a lens to enhance transmission of light to the distal end  137  of the rolling diaphragm syringe  135 . 
     In another example, as shown in  FIGS. 19A and 19B , the pressure jacket  210  may include the electromagnetic radiation source  212  as mentioned herein positioned at the proximal end  218  thereof. In such instances, the light produced by the electromagnetic radiation sources  212  may be directed up through the pressure jacket  210 , and internal reflection within the pressure jacket  210  creates the illuminated identification pattern at the conical distal end  137  of the rolling diaphragm syringe  135  when the syringe is filled with fluid. In another aspect, the pressure jacket  210  may be coated with a substance that produces a “one way mirror” to properly distribute the internal reflection of the electromagnetic radiation while allowing observation by the technician. In addition or alternatively, the electromagnetic radiation source and the pressure jacket  210  may be polarized to prevent electromagnetic radiation from exiting pressure jacket  210 . 
     The electromagnetic radiation is collected and directed towards the distal end  137  of the rolling diaphragm syringe  135  to create an illuminated identification pattern when filled with fluid. The inside of the distal end  137  of the rolling diaphragm syringe  135  may be angled similar to distal end  24  of syringe  12  discussed herein to generate a halo  120  in a similar manner Alternatively or in addition, as shown in  FIG. 20 , a protruding component  224  may be incorporated in or positioned near the distal end  137  of the rolling diaphragm syringe  135  to distribute the light to generate the halo  120 . The protruding component  224  may have various configurations for various purposes. For example, the protruding component  224  may be a reflective surface that reflects light in various directions to enhance visualization of the halo  120  or to show another indication that fluid is present. The protruding component  224  may be a prism, mirror, textured surface, or some other geometrical/material alteration to disperse/absorb light in such a way that it allows for indication of fluid presence, fluid type, or other characteristics of the syringe  135 . 
     Since a cap  390  may be used with rolling diaphragm syringe  135  as described herein, the cap  390  may be manufactured from a translucent or transparent material so that the halo may be observed through the cap material. As the electromagnetic radiation is transmitted to the distal end  137  of the rolling diaphragm syringe  135 , it causes such a transparent or translucent cap  390  to illuminate. The intensity of the illumination of the cap  390  varies depending on the fluid contained within the syringe as described herein. For instance, if a fluid is provided within the syringe, the cap  390  is illuminated much brighter than if air is present within the syringe. 
     II. Image Recognition of the Illuminated Identification Pattern and Various other Aspects of the Fluid Injection System 
     Having discussed various examples of radiation sources, syringes, how the electromagnetic radiation or light beam is directed through the syringe to form an illuminated identification pattern, sensors  114  for identifying the illuminated identification pattern and for monitoring or controlling operation of the injector  10  (shown in  FIG. 1 ) based on identification of the illuminated identification pattern and various other aspects of the fluid injector  10  will now be discussed in detail. While the systems and methods discussed herein with be discussed with reference to the fluid injector  10  including the syringe  12 , all of the concepts discussed herein may be utilized with the rolling diaphragm syringe  135  as well. 
     With reference to  FIGS. 1, 6, and 9-12 , the fluid verification system  110  is configured as an image recognition system that includes at least one sensor  114 , such as an image capture device, positioned having a field of view directed to at least the distal end  24  of the syringe  12 , a central processing unit  116  including a controller operatively connected to the sensor  114  and configured to process the images obtained from the sensor  114  using suitable image processing software, and a display  118  operatively connected to the central processing unit  116  for displaying the results of the image processing performed by the central processing unit. In one example, the image processing software may be the Insight Explorer software from Cognex Corporation of Natick, Mass. and the sensor  114  may be a DataMan  100  camera also from Cognex Corporation. In addition, the at least one sensor  114  and the central processing unit  116  may be integrated into a single component or provided as individual components. Further, the at least one sensor  114 , the fluid injector  10 , the display  118 , and/or the central processing unit  116  may be in wired communication or may communicate wirelessly, for example via Bluetooth, WiFi, or other conventional wireless communication technology. 
     In another example, the sensors  114  can be an alternative type of optical sensor, such as an electromagnetic radiation detector or other suitable sensor as is known in the art. In some examples, the at least one sensor  114  is a digital camera that can be configured to obtain a digital image of at least the distal end  24  of the barrel  18  when the electromagnetic radiation source  112  is turned on. In other examples, the at least one sensor  114  can be an infrared radiation detector, ultraviolet light detector, ultrasound imaging device, or any other suitable sensor for identifying electromagnetic radiation emitted from the electromagnetic radiation source  112 . 
     As will be appreciated by one of ordinary skill in the art, the at least one sensor  114  or detector can be adapted specifically for identifying a wavelength of electromagnetic radiation or light associated with the electromagnetic radiation source  112  and the illuminated identification pattern produced therewith. For example, the at least one sensor  114  can include various filters or tuned or attenuated optical elements for identifying only radiation within an expected wavelength (e.g., electromagnetic radiation within a wavelength emitted by the electromagnetic radiation source  112 ). Additionally, the syringe  12  itself can be used as a filter by altering the material properties (e.g., color, molecular alignment, pigment additive, polarized surface) to filter light of a given wavelength to achieve an optimized visualization by the user. Alternatively, image processing techniques, known in the art, can be used to remove portions of obtained images outside of the expected wavelength, thereby reducing an influence of ambient light and increasing sensitivity for the illuminated identification pattern. 
     Using features of the fluid verification system  110  described herein, various aspects of a fluid injection procedure can be monitored prior to and during delivery of a fluid to quickly provide information to a technician of details of the injection procedure in a readily apparent manner These details of the injection will be discussed herein. 
     A. Air Detection 
     1. Using an Image of an Illuminated Identification Pattern 
     All current injector systems rely upon the personal inspection of the technician to determine if air is present in the syringe prior to the start of an injection procedure. The fluid verification system  110  is configured to provide detection of air using at least one sensor  114  and image recognition software executed by a central processing unit  116  to allow the technician to have additional corroboration of his/her conclusion on the status of the syringes. In addition, the technician can manually determine whether air is present by looking at the syringe to determine whether the illuminated identification pattern is present thus providing an alternative or two-pronged approach to air detection. 
     In one example, the fluid verification system  110  determines whether air is present by taking an image of the distal end of the syringe  12  to determine if the halo  120  has been generated in the syringe  12  by the electromagnetic radiation source  212  with the sensor  114  and using the image recognition software of the central processing unit  116  to review and analyze the image to measure one or more properties of the halo  120  or illuminated identification pattern to determine if the syringe is properly filled with fluid prior to injection. More specifically according to one aspect and with reference to  FIG. 21 , at step  300 , the at least one sensor  114  is positioned to capture an image of at least a portion of the syringe  12  that includes the halo  120  or other illuminated identification pattern. Thereafter, and with reference to  FIGS. 22 and 23 , at step  302 , a bottom edge  301  of a meniscus of the fluid contained within the syringe  12  and/or the bottom edge  303  of the halo  120  is measured or determined by the system  110 . These edges  301 ,  303  are identified in the image by the software provided on the central processing unit  116 . More specifically, the image processing software executed by the central processing unit  116  may be able to detect the edges through a variety of different methods. One method is to determine the change in contrast between neighboring pixels in the image of the edge. Alternatively, a contrast change over several adjacent pixels might indicate the presence of the edge. This change is indexed over each pixel within a search window to find areas where the contrast change reaches a threshold. For example, the change is flagged if the image recognition software finds a spot where a light colored pixel is adjacent to a dark pixel. If it is found that this threshold is crossed with several pixels in a row, oriented specifically in a predetermined direction, then the image processing software determines that this is an “edge”. In this particular application, the dispersion of light caused by the lens effect of the meniscus causes a darkened area of fluid at the meniscus location. Specifically, there is an edge that can be found at the top and the bottom of the meniscus as shown most clearly in  FIG. 23 . 
       FIG. 22  is an image of a syringe  12  where no air is present, and  FIG. 23  is an image obtained by sensor  114  where air is present in the syringe  12 . As can be seen from these images, the halo  120  is larger when no air is present as shown in  FIG. 22 . This allows for the determination of air using imaging processing techniques as discussed in detail herein. 
     At step  304 , a distance  305  from the bottom edge  301  of the meniscus to the bottom edge  303  of the halo  120  is determined using the image processing software provided on the central processing unit  116 . Once the bottom edge  301  of the meniscus is determined, the location of this edge in space can be found. Specifically, the bottom edge  303  of the halo  120  can be determined and this bottom edge  303  of the halo  120  always stays fixed as long as the syringe  12  and the sensor  114  do not move. Accordingly, the image processing software is then able to determine a distance from the bottom edge  301  of the meniscus to the bottom edge  303  of halo  120 . 
     At step  306 , the distance  305  determined in step  304  is compared to a predetermined distance. The predetermined distance was found by creating a curve, such as the curve shown in  FIG. 24 . This curve was created by taking a full syringe  12  and replacing known increments of fluid with equal volumes of air Images were then taken after each increment of fluid was replaced and the distance from the bottom edge of the meniscus to the bottom edge of the halo  120  was measured using the image recognition software on the central processing unit  116 . The curve is then plotted and an equation is fit. The equation is then provided to a logic algorithm in which the data of the curve in  FIG. 24  is embodied to calculate the volume of air present based on the distance between the two edges. 
     If the measured distance  305  is greater than the predetermined distance, it can be determined that substantially no air is present and the injector can be armed to proceed with an injection at step  308 . On the other hand, if the measured distance  305  is less than the predetermined distance, an indication that air is present in the syringe  12  is provided at step  310  and the fluid injector  10  is disabled from conducting an injection procedure at step  312 . Alternatively, if air is present, the fluid injector  10  may perform a purge process to purge the air from the syringe and then repeat the measurement procedure of  FIG. 21 . This purge process may be repeated until the measuring process indicates that substantially no air is present in the syringe and the injection procedure may proceed. 
     2. Using details provided on the Barrel of the Syringe 
     An alternative approach to detecting air in a syringe using image processing techniques is to obtain an image of certain features provided on the barrel of the syringe. Specifically, and with reference to  FIGS. 25 and 26 , the syringe  12  may include at least one fluid dot  339  on the surface of the syringe  12  that is visible by the sensor through the fluid contained within the syringe  12 . The use of fluid dots is described in U.S. Pat. No. 5,254,101, to Trombley, III, the disclosure of which is incorporated in its entirety by this reference. Due to the different properties of different fluids, this dot  339  will have a different appearance based on the fluid contained within the syringe. Accordingly, if air is contained within the syringe  12 , the fluid dot  339  will have a certain configuration, such as an oval shape, when viewed in an image, which can be detected as followed. First, at step  340 , the at least one sensor  114  is positioned to capture an image of at least a portion of the syringe  12  that includes the fluid dot  339  through the fluid contained within the syringe  12 . Thereafter and with reference to  FIG. 27 , at step  342 , the fluid dot  339  is identified in the image using pixel contrast thresholds. Specifically, the fluid dot  339  is identified by detecting the edges thereof in a manner similar to the manner in which the bottom edge of the meniscus is determined as described herein. 
     Next, at step  344 , since the shape of the fluid dot  339  when various fluids are provided within the syringe are known, pattern matching techniques can be utilized to determine whether air or fluid is within the syringe  12 . Accordingly, a template of a fluid dot  339  when fluid is present within the syringe can be matched to the image obtained in step  340 . At step  346 , if the template matches the image obtained in step  340 , it can be determined that no air is present and the injector can be armed to proceed with an injection at step  348 . On the other hand, if the template does not match, an indication that air may be present in the syringe  12  is provided at step  350  and the fluid injector  10  is disabled from conducting an injection procedure at step  352  until a repeated analysis step indicates that the air has been removed, for example by purging. 
     While fluid dots  339  were described herein as being utilized, various other shapes can be utilized and imaged to determine whether air is present in the syringe. This is due to the fact that a cylindrical syringe barrel is, in effect, a lens itself. Utilizing the curvature of the barrel wall, images can be captured which will appear different to the at least one sensor  114  if there is air or fluid in the syringe  12 . This phenomenon can be utilized to detect the presence of gross air inside of a syringe. Additionally, the relative size of the image may allow for determination of fluid type within the syringe (e.g., larger image will be seen through contrast, while a small image will be seen through saline, for example, due to differences in index of refraction between the fluids). More specifically, since the syringe barrel  18  acts as a cylindrical lens when it is full of fluid, the fluid dots  339  stretch on the horizontal axis. Therefore, an oval shaped fluid dot  339  is stretched horizontally without impacting the vertical height. This is the way the oval fluid dot  339  on an empty syringe becomes a circle or more circular on a filled syringe to the sensor  114 . The sensor may measure the change in the horizontal width of the fluid dot  339  to determine various features of the fluid contained within the syringe. Due to this principle a variety of different shapes may be used to achieve the above described effect of the fluid dots  339 , for example by measuring differences in the non-vertical features of the fluid dots  339 . 
     3. Using Brightness Measurements 
     According to other aspects, air detection is also possible by imaging a portion of syringe having electromagnetic radiation from a source thereof passing therethrough and determining the average pixel brightness value of a region of interest, such as a portion of the distal end  24  of the syringe, for example the halo region as described herein. Such an arrangement is illustrated in  FIG. 28 , for instance, which shows a syringe  12  filled with contrast having electromagnetic radiation, in the form of laser light beam  354 , having a specific wavelength, passing therethrough. As can be seen in  FIG. 28 , when the syringe is filled with contrast, a path of a distinct laser beam  354  can be seen as it passes through the contrast. Without being limited by any theory, it is believed that the contrast agent dissolved in the solution scatters the electromagnetic radiation in the laser beam  354 , providing an observable laser beam pathway. No such laser beam is present if the syringe  12  is filled with air (see  FIG. 27 ). Accordingly, an average pixel brightness (e.g., 0-255 intensity units) in an image of the portion of the distal end  24  of the syringe  12  when filled with fluid, as shown in  FIG. 28 , is much higher than when the syringe is filled with air as evidenced by the presence of laser beam  354  due to scattered laser light. Accordingly, the presence of air or contrast can be determined using brightness by shining a laser electromagnetic radiation through a portion of the syringe barrel, obtaining an image of the syringe through which the electromagnetic radiation is being passed; determining a region of interest, such as near the distal end  24 , of the syringe; determining the average pixel brightness value for the region of interest by assigning each 8 bit pixel within the region of interest a brightness value from 0-255 intensity units then averaging these brightness values; and comparing the average brightness value to a known brightness value to determine whether fluid or air is present within the syringe  12 . Scattering of laser light by contrast, compared to non-scattering by air, may be observed by shining the laser light through any portion of the fluid in the syringe. In the aspect described herein, the laser light may be shown through the distal end of the syringe due to a particular location of the at least one sensor relative to the syringe barrel. One skilled in the art would recognize that other locations of the at least one sensor may be used to determine intensity of laser light depending on the location of the path of the laser light. 
     B. Fluid Differentiation 
     All of the above described image processing techniques for distinguishing air from fluid within a syringe may also be utilized to identify the type of fluid contained within a syringe. For instance, contrast can be accurately differentiated from saline and different types of contrast can be accurately differentiated from each other using the above described imaging processing techniques due to the manner in which different fluids interact with light. In particular, with reference to  FIGS. 29 and 30 , scattering of the laser light may differ according to the fluid within the syringe. For example, laser beam path  354  displays a weak intensity passing through saline compared to intensity of a laser beam path  354  passing through contrast in a syringe. 
     1. Utilizing the Illuminated Identification Pattern 
     With further reference to  FIGS. 29 and 30 , the fluid verification system  110  according to various aspects herein may determine whether a syringe contains saline or contrast by taking an image of the halo  120  generated in the syringe  12  by the electromagnetic radiation source  112  with the sensor  114  and using the image recognition software of the central processing unit  116 . While other methods for differentiation between saline and contrast are described in detail herein, the same technique may be used to differentiate between different types or concentrations of contrast. First, the at least one sensor  114  is positioned to capture an image of at least a portion of the syringe  12  that includes the halo  120 . Thereafter, a distance between a bottom edge  301  of a meniscus at the air/fluid interface within the syringe  12  and the bottom edge  303  of the halo  120  is measured by the system  110 . These edges  301 ,  303  are identified in the image by the software provided on the central processing unit  116  from pixel contrast thresholds as described herein.  FIG. 29  is an image obtained by sensor  114  of a syringe  12  containing saline and  FIG. 30  is an image obtained by sensor  114  where contrast is present in the syringe  12 . As can be seen from these images, the distance between edges  301  and  303  is greater ( FIG. 29 ) when saline is present in the syringe compared to the distance between edges  301  and  303  when contrast is present in the syringe ( FIG. 30 ). With respect to differentiation of contrast, the halo  120  will also be a different size depending on the type of contrast that is present in the syringe. This allows for differentiation of the type of fluid—saline, and various contrast agents—contained in the syringe using imaging processing techniques as discussed in greater detail herein. 
     A distance from the bottom edge  301  of the meniscus between the air/fluid interface and the bottom edge  303  of the halo  120  is determined using the image processing software provided on the central processing unit  116  as described herein. Then, this distance may be compared to various predetermined distances corresponding to various fluids contained within the memory of the central processing unit  116 . If the distance corresponds to the first predetermined distance for saline, an indication  356  that saline is contained in the syringe  12  is automatically displayed on the display  118 , and if the distance corresponds to the second predetermined distance for a specific contrast, an indication  358  that the specific contrast is contained in the syringe  12  is automatically displayed on the display  118 . 
     Alternatively, pattern matching techniques based on the halo  120  size may be utilized to determine whether the syringe contains air, saline, or various contrast agents. For instance, the image processing software provided on the central processing unit  116  can determine a height of the halo  120  from the bottom of the threads of nozzle  22  to the bottom edge of the halo  120  and determine the presence and fluid type based on the height as described in detail herein. In addition, the image processing software may also be programmed for specific contrast agents or other fluids utilizing pattern recognition by taking a training image of a syringe known to have a particular contrast contained therein. This training image records all of the dimensions of the halo  120  including height. Then, the image processing software compares all of the features of later images it captures to the training image for comparison. If the images exceed a threshold of similarity then the system will provide an indication that the syringe  12  contains contrast or saline other than the contrast it has been trained for. 
     2. Using details provided on the Barrel of the Syringe 
     An alternative approach to determining the type of fluid contained within a syringe using image processing techniques is to obtain an image of certain features provided on the syringe. Specifically, and with reference to  FIGS. 27, 31 and 32 , the syringe  12  may include at least one fluid dot  339  that is visible by the sensor through the air or fluid contained within the syringe as described herein. Due to the different properties of air and different fluids, this dot  339  will have a different appearance, specifically along a horizontal axis, based on air or the fluid contained within the syringe as seen by comparing the fluid dot  339  of  FIG. 27 , seen through a syringe  12  containing air, the fluid dot  339  of  FIG. 31 , which is seen through a syringe  12  containing saline, and the fluid dot  339  of  FIG. 32 , which is seen through a syringe  12  containing contrast. Accordingly, if air is contained within syringe  12 , the fluid dot  339  will have a more shorter distance in the horizontal direction when viewed by the sensor, if saline is contained within the syringe  12 , the fluid dot  339  will have a certain configuration when viewed in an image and if contrast is contained within the syringe  12 , the fluid dot  339  will have a certain configuration (i.e., longer distance in the horizontal direction) when viewed in an image. Therefore, the type of fluid contained within the syringe can be detected as follows. 
     First, the sensor  114  is positioned to capture an image of at least a portion of the syringe  12  that includes the fluid dot  339  or other indicator feature on the syringe barrel through the fluid contained within the syringe  12 . Thereafter, the fluid dot  339  is identified in the image using pixel contrast thresholds as described herein. Next, at step  344 , since the shape of the fluid dot  339  when various fluids are provided within the syringe are known, pattern matching techniques can be utilized to determine whether air, saline or contrast is present within the syringe  12 . For example, a template of a fluid dot  339  when saline is present within the syringe can be matched to the image. If the template matches the image, it can be determined that saline is present and an indication  356  that saline is present in the syringe  12  is provided on the display  116 . On the other hand, if the template does not match, a template of a fluid dot  339  when contrast is present within the syringe can be matched to the image. If the template matches the image, it can be determined that contrast is present and an indication  358  that contrast is present in the syringe  12  is provided on the display  118 . Further if the template for saline or various contrasts do not match, a template for a fluid dot  339  when air is present within the syringe can be matched to the image. If air is determined to be in the syringe, the injection procedure may be halted automatically. 
     Various other shapes, other than oval fluid dots  339 , can be utilized and imaged to determine the type of fluid contained within the syringe as described in greater detail herein. 
     3. Using Brightness Measurements 
     According to certain aspects, fluid differentiation may also be possible by imaging a portion of syringe having electromagnetic radiation from a source thereof passing therethrough and determining the average pixel brightness value of a region of interest, such as a portion of the distal end  24  of the syringe. Returning to  FIGS. 27, 29, and 30 , when the syringe is filled with contrast (see  FIG. 30 ), a distinct laser beam path  354  can be seen. The laser beam path  354  is much less distinct if the syringe  12  contains saline (see  FIG. 29 ) and is essentially indiscernible when passing through a syringe filled with air. According to certain embodiments, a laser that emits light having wavelengths within the green region of the visible light spectrum may be used. Accordingly, an average pixel brightness (e.g., 0-255 intensity units) in an image of the portion of the distal end  24  of the syringe  12  when filled with contrast is much higher than when the syringe is filled with saline or air. Accordingly, the type of fluid contained within the syringe can be determined by obtaining an image of the syringe through which the electromagnetic radiation is being passed; determining a region of interest of the syringe, such as near the distal end  24  (although other regions of the syringe may be used); determining the average pixel brightness value for the region of interest by assigning each 8 bit pixel within the region of interest a brightness value from 0-255 intensity units then averaging these brightness values; and comparing the average brightness value to a known brightness value to determine whether contrast, saline, or air is present within the syringe  12 . This methodology may also be used to differentiate between different types (e.g., brands or solute concentration) of contrast. 
     C. Fluid Source Status 
     According to other aspects, by using the at least one sensor  114  to obtain images of various portions of the fluid injector  10 , various information regarding the status of fluid sources can be obtained. For example, an image of a fluid container, such as a saline bag or contrast bottle, and its contents can be obtained and the amount of fluid within the bottle can be determined using image processing techniques. This information can be provided to the central processing unit and a bottle may be displayed on display  118  illustrating the amount of fluid present or remaining within the bottle. In addition, optical character recognition may be used to determine the type of fluid contained within the bottle and this information can also be displayed on the display  118 . Moreover, in certain aspects the fluid remaining in the bottle may be constantly monitored prior to, during, and after an injection procedure and the updated remaining volume may be displayed real-time on the display  118 . In still other aspects, the central processing unit  116  may monitor the remaining volume and provide a warning if the volume of one or more of the contrast or saline are not sufficient to complete an injection procedure. This feature may be combined with a patient schedule for a series of patients to provide real-time feed-back on the required volume of contrast and/or saline so that a technician may be sure to have sufficient supply on hand to complete all scheduled injection procedures and may, for example when a contrast warmer is used, ensure that the subsequent container(s) of contrast is at the desired injection temperature when the contents of the currently used bottle are almost used up. 
     More specifically, the same methodology utilized for recognizing the size of the halo  120  with pattern recognition techniques described herein may be utilized for determining fluid source status. For example, the image processing software looks for geometrical components in the image to compare to training images with known objects. In one example, if the image processing software is trained to know what the letters of the alphabet look like and the size and angular thresholds for recognition are lowered, then the image processing software is effectively able to read the label of the bottle and determine the manufacturer, contrast type, expiration dates, etc. Additionally, the fluid level within the bottle can be identified using edge detection techniques described herein and the image processing software can be programmed to calculate the volume remaining in the bottle until it needs to be replaced by a user. This aspect utilizes similar calculations as used with the volume of air present in the syringe as described herein. Specifically, a curve may be generated and an equation fit for each of the bottle sizes and shapes or an algorithm may be developed to determine remaining volumes. 
     D. Determination of Syringe Type (size/presence) 
     In certain aspects, the fluid verification system  110  may also be utilized to determine various properties or parameters of the syringe  12  inserted into the injector, for example, syringe type, size, manufacturer, manufacturing date or lot number, suitability for a specific injection procedure, prior use, remaining use lifetime, maximum pressure, etc., prior to a fluid injection procedure. This information may be used to identify the syringe and manufacturer, determine whether the syringe is previously used, and determine desired flow rates, pressures, volumes, etc. In one example, with reference to  FIGS. 33 and 34 , the size of the syringe may be determined as follows. First, the at least one sensor  114  is positioned to capture an image of at least a portion of the syringe  12  such as the distal end  24  of the syringe  12 . Since the position of the at least one sensor  114  is known, the location of certain features of a syringe  12  of a first size, such as the nozzle  22  or the halo  120 , and the location of certain features of a syringe  12  of a second size, such as the nozzle  22  or the halo  120 , in the image of the distal end  24  of the syringe are also known. Using this fact, pattern matching techniques can be utilized to determine the size of a syringe  12  used with the fluid injector  10 . For example, a template  365  of a syringe of a first size (e.g., 150 mL) can be applied to the image. If the template matches the image, the central processing unit  116  can determine that the syringe is a 150 mL syringe and an indication  367  of the size of the syringe  12  is provided on the display  118 . On the other hand, if the template  365  does not match, a template  369  of a syringe of a second size (e.g., 200 mL) can be applied to the image. If the template matches the image, the central processing unit  116  can determine that the syringe is a 200 mL syringe and an indication  367  of the size of the syringe  12  is provided on the display  118 . If none of the stored templates match, an indication can be provided on the display  118  that no syringe is present or that the syringe identity cannot be determined. In another aspect, the at least one sensor  114  may be located in a position to image at least one identification marking on syringe  12 , such as a bar code containing information on the syringe, such as for example, manufacturer, manufacturing date or lot, one or more syringe parameters, a specific identity/security code that can be confirmed by the central processing unit to determine if the syringe is authentic or is potentially being reused, etc., and transmit the image of the identification marking to the central processing unit  116  for deconvolution. 
     E. Tubing Presence Indicator 
     Similar to the determination of the syringe type, in other aspects the presence or absence of a fluid path set  17  connected to the syringe  12  can also be determined using imaging processing techniques. This information can be utilized by the central processing unit  116  to disable the injector if an operator inadvertently attempts to start an injection procedure without a fluid path set  17  being connected to the nozzle  22  of the syringe or if the fluid path set has not been primed. In one example, with reference to  FIGS. 35 and 36 , the sensor  114  is positioned to capture an image of the nozzle  22  of the syringe  12 . Since the position of the sensor  114  is known, the location of certain features of the syringe  12 , such as the nozzle  22  and the fluid path set  17 , if connected to the nozzle  22 , in the image of the syringe  12  are also known. Using this fact, pattern matching techniques can be utilized to determine whether a fluid path set  17  is connected to the syringe  12 . For example, a template  373  of a syringe  12  having a fluid path set  17  connected thereto can be applied to the image. If the template matches the image, the central processing unit  116  can determine that the fluid path set  17  is connected to the syringe  12  and an indication  375  that the fluid path set  17  is present is provided on the display  118  (see  FIG. 31 ). On the other hand, if the template  373  does not match, the central processing unit  116  can determine that no fluid path set  17  is present and an indication  377  that no fluid path set  17  is present is provided on display  118 . 
     F. Spike or Transfer Set Presence Indicator 
     With reference to  FIG. 37 , according to certain aspects, a fluid transfer device  46  is often used to fill a syringe  12  from a fluid container  44 . The transfer device  46  typically includes a spike  48  having at least one fluid path, and in certain aspects an air passage, for puncturing the seal of the fluid container  44 , a container holder or cup  50  for holding the fluid container  44  on the spike  48 , a valve (not shown), such as a check valve, for allowing fluid to enter the syringe  12  and a syringe support member or sleeve  54  for holding the syringe  12  in relationship to the transfer device  46 . 
     During a filling procedure, after the syringe  12  is mounted on the fluid injector  10 , the plunger  26  is advanced to expel air from the syringe  12 . The syringe  12  is then ready to be filled with fluid. The transfer device  46  may then be inserted onto the fluid container  44  such that the spike  48  pierces the seal of the fluid container  44 . The syringe support member  54  of the transfer device  46  may then be placed over the nozzle  22  of the syringe  12 . Within the support member  54 , the luer tip of the syringe  12  engages and actuates the valve to open a passage for fluid to flow from the container  44  to the syringe  12 . To aspirate the contents of the fluid container  44  into the syringe  12 , the injector piston (not shown) retracts the plunger  26  of the syringe  12 . After filling the syringe  12 , the fluid container  44  is removed from the transfer device  46 . Filling of the syringe with fluid may be monitored, for example in real-time, by the at least one sensor  114  to ensure accurate filling of the syringe. 
     Once filling is complete, it may be desirable for the operator to be provided with an indication of whether the fluid transfer device  46  has been removed. This can be automatically done using the fluid verification system  110  described herein. Specifically, with reference to  FIGS. 38 and 39 , the at least one sensor  114  is positioned to capture an image of the nozzle  22  of the syringe  12 . Since the position of the at least one sensor  114  is known, the location of certain features of the syringe  12 , such as the nozzle  22  and the fluid transfer device  46 , if connected to the nozzle  22 , in the image of the syringe  12  are also known. Using this fact, pattern matching techniques can be utilized to determine whether a fluid transfer device  46  is connected to the syringe  12 . For example, a template  383  of a syringe  12  having a fluid transfer device  46  connected thereto can be applied to the image. If the template matches the image, the central processing unit  116  can determine that the fluid transfer device  46  is connected to the syringe  12  and an indication  385  that the fluid transfer device  46  is present is provided on the display  118  (see  FIG. 38 ). This information may also be displayed on a touch screen controller  82  of a fluid injection system  600  as shown in  FIG. 58 . On the other hand, if the template  383  does not match, the central processing unit  116  can determine that no fluid transfer device  46  is present and an indication  387  that no fluid transfer device  46  is present is provided on the display  118  (see  FIG. 39 ). 
     G. Tubing Purged Indicator 
     With reference to  FIG. 40 , in certain aspects of the fluid injectors  10  described herein, a purge container  550  may be configured to be connected to the end of a connector  552  of the fluid path set  17  that delivers contrast media or other fluid to a patient during a purging procedure prior to an injection. When the fluid path set  17  is primed or purged of air prior to an injection procedure, the purge container  550  may collect the discharge of contrast media from the end of the fluid path set  17  that delivers the media to the patient when the syringe  12  and fluid path set  17  are purged and primed and provide an indication that the purge is acceptable based on the amount of contrast contained therein. In certain aspects, an operator may visually inspect the purge container  550  to determine that an acceptable amount of contrast is contained therein and that the purge was acceptable and the syringe and fluid path are primed with fluid. However, in certain aspects this process may be automated by capturing an image of the purge container  550  with the at least one sensor  114  and processing the image using the image processing techniques discussed herein. 
     For instance, with reference to  FIGS. 41, 42A, and 42B , a fluid dot  554  or other indicator marking, similar to the fluid dot  339  discussed herein, may be formed or provided on a surface of the purge container  550 . The at least one sensor  114  is positioned such that it will image the fluid dot  554  through any fluid contained within the purge container  550 . Due to the different properties, such as index of refraction, of different fluids and/or the selected curvature of the purge container  550 , this dot  554  will have a different appearance based on the fluid contained within the syringe and purge container  550 . Accordingly, if air is contained within the purge container  550 , the fluid dot  554  will have a first configuration when viewed in an image, for example according to one aspect as shown in  FIG. 42A  and, if a fluid, such as contrast or saline, is contained within the purge container  550 , the fluid dot  554  will have a second configuration, for example as shown in  FIG. 42B . The configuration of the fluid dot  554  can be detected as followed. First, the at last one sensor  114  is positioned to capture an image of at least a portion of the purge container  550  that includes the fluid dot  554  through the fluid contained within the purge container  550  after the syringe and tubing set  17  have been primed and purged of air. Thereafter, since the shape of the fluid dot  554  when various fluids are provided within the purge container  550  are known, pattern matching techniques can be utilized to determine whether air or fluid is within the purge container  550 . Accordingly, a template of a fluid dot  554  when a certain fluid, such as contrast or saline, is present within the purge container  550  can be matched to the image of the fluid dot  554  obtained by the sensor  114 . If the template matches the image, it can be determined that no air is present in the syringe and tubing set  17  and that purge container  550  contains sufficient fluid to indicate that the system has been primed and a signal can be sent to the fluid injector  10  that the fluid path set  17  has been properly purged and primed. An indication may also be provided on display  118  that the fluid path set  17  has been properly purged and primed and that the injector is ready for the injection procedure. According to certain aspects, the priming and purging of the syringe and fluid path set may be monitored real-time. In this aspect, the at least one sensor  114  monitors the fluid dot  554  on purge container  550  as the configuration of the fluid dot  554  changes during the priming procedure, thus monitoring the change in volume of the purge container  550  and indicating when sufficient fluid has been primed into the system and no additional air remains in the system. According to one aspect, an algorithm may be utilized that correlates volume change in purge container  550  with fluid flow through tubing set  17  to confirm completion of the priming operation. 
     Alternatively according to another aspect, with reference to  FIGS. 43A and 43B , rather than using a fluid dot  554 , one or more reference lines  556  may be formed or provided on a surface of the purge container  550 . The reference line  556  may be printed on the surface of the purge container  550 , molded onto the surface of the purge container  550 , or formed or provided on the surface of the purge container  550  in any other suitable manner The at least one sensor  114  is positioned such that it will image the reference line  556  through any fluid contained within the purge container  550 . Once an image of the purge container  550  is obtained, the image processing software provide on central processing unit  116  identifies a top edge  558  of the fluid F contained within the purge container  550  along with the reference line  556  using pixel contrast thresholds as described herein. A distance  560  from the top edge  558  of the fluid F contained within the purge container  550  to the reference line  556  is determined using the image processing software provided on the central processing unit  116 . The central processing unit  116  compares this distance  560  to various predetermined distances corresponding to acceptable and unacceptable purging processes to determine if the purge is acceptable and the system is primed. Again, the purge/prime operation and change in volume in the purge container  550  may be monitored real-time as the syringe and fluid path set  17  are primed to ensure accurate priming of the system. 
     In yet another alternative, with reference to  FIGS. 44A and 44B , an indicator line  562  having the shape shown may be formed or provided on a surface of the purge container  550 . The indicator line  562  may be printed on the surface of the purge container  550 , molded onto the surface of the purge container  550 , or formed or provided on the surface of the purge container  550  in any other suitable manner The sensor  114  is positioned such that it will image the indicator line  562  through any fluid contained within the purge container  550 . Due to the properties of different fluids and/or the selected curvature of the purge container  550 , the indicator line  562  appears to be a different length in an image when fluid is present as compared to when air is present. In addition, the indicator line  562  may have a brighter appearance when viewed in air than when viewed in fluid. Accordingly, pattern matching techniques and/or brightness level measurement of the indicator line  562  can be performed on an image of the indicator line  562  by the image processing software on the central processing unit  116  to determine whether fluid or air is present within the purge container  550 . Based on this determination, the central processing unit  116  can determine the acceptability of the purge and provide an indication, via display  118 , to an operator. Again, the purge/prime operation and change in volume in the purge container  550  based on changes in indicator line  562  may be monitored real-time as the syringe and fluid path  17  are primed to ensure accurate priming of the system. One of skill in the art will recognize that other configurations of the indicator line  562  are possible and that the image recognition software and algorithms described herein may monitor changes in the configuration of the indicator line  562  during a purging/priming operation and indicate to the technician that the system has been correctly primed and is ready for use in an injection procedure. Such other configurations are within the scope of this disclosure. 
     With reference to  FIG. 45 , an alternative configuration of the purge container  550  is illustrated. This purge container  550  is also configured to be connected, during a purging procedure, to the end of a connector  552  of the fluid path set  17  that is designed to deliver contrast media or other fluid to a patient during a subsequent diagnostic injection procedure. The purge container  550  includes a cylindrical body  563  having a proximal end  564  and a tapered distal end  565  similar to the tapered distal end  24  of the syringe  12  described herein. An electromagnetic radiation source  566 , such as an LED, is positioned beneath the proximal end  564  of the cylindrical body  563 . Accordingly, when the purge container  550  is filled with an appropriate amount of fluid, a halo  567  is generated similar to the manner in which halo  120  is formed within the syringe  12  as described herein. This allows the operator to quickly and easily determine if an acceptable amount of contrast is contained therein and that the purge was acceptable if the halo  567  is present and that the syringe and fluid path set  17  are appropriately primed. In addition, this process may be automated, and in certain aspects monitored real-time, by capturing one or more image of the halo  567  generated within the purge container  550  with at least one sensor  114  and processing the image using the image processing techniques discussed herein. 
     With reference to  FIG. 46 , according to an aspect, the fluid path set  17  may be altered to allow for image recognition of an image of the tubing obtained by at least one sensor  114  to determine whether the fluid path set  17  has been sufficiently purged. For example, as shown in  FIG. 46 , the tubing of the fluid path set  17  may include a fiber optic cable  610  positioned adjacent thereto. The fiber-optic cable  610  may also be co-extruded with the tubing of the fluid path set  17  such that the fiber-optic cable  610  is embedded within the tubing or it may be placed inside the tubing of fluid path set  17 . In another example, a reflective surface may be provided on the inside or the outside of the tubing of the fluid path set  17  to transmit light via internal reflection throughout the tube length or alternatively the fluid path material may be selected to have an index of refraction suitable for internal reflection as described herein. This will allow light to be reflected throughout the length of the tubing of the fluid path set  17  when fluid is present (similar to how a light pipe works) and result in a visible indicator that the tubing of the fluid path set  17  is purged and filled with fluid. This visual indicator can be an illuminated component at the end of the tube set which can be recognized by the sensor  114  or simply by the operator. If air is present in the fluid path set  17 , for example when the tubing has not been totally primed, internal reflection of the light will not occur and the “light pipe” effect will not be observed. 
     Furthermore, the tubing of the fluid path set  17  can be configured to have a connector (not shown) on the end thereof that is attached to the injector  10  or positioned in a location where an electromagnetic radiation source is emitting through a section of the connector. The entire connector would only light up according to this embodiment if it is full of fluid indicating that the tubing of the fluid path set  17  is completely purged of air and is primed and ready for use. The electromagnetic radiation source may be wireless, battery powered, or connected to a power source on the injector. This means that it can have either direct or indirect contact with the tubing of the fluid path set  17  and can be either disposable or re-usable according to specific aspects. 
     In yet another example, the image processing software provided on the central processing unit  116  can be used to determine the volume of fluid required to purge the fluid path set  17 . More specifically, the system can determine how much air is present within the syringe  12  using any of the methods described herein. Thereafter, the image processing software on the central processing unit  116  can determine the type of fluid path set  17  connected to the syringe using pattern matching techniques as described herein. Using this information, the central processing unit  116  can calculate the volume of fluid required to purge/prime the fluid path set  17 . Using this information, the central processing unit  116  may instruct the injector  10  to operate the syringe to move the plunger a sufficient distance corresponding to the volume of air calculated to be in the syringe and fluid path set  17 . The plunger may be moved an additional distance to eject a further volume to ensure complete priming of the system. 
     In another configuration of the purge container  550 , one or more sensors may be associated therewith. More particularly, a component (not shown) may be provided in the purge container  550  that moves when fluid enters (meaning the tubing is being purged). The moving component may be detected by the sensor  114  or be a visual indicator for the operator and a volume of fluid coming into the purge container  550  may be determined to confirm when priming of the syringe and fluid path set  17  is complete. 
     For example, in one aspect, the component could be an air filter (e.g. a Porex brand filter) which allows air to pass through as the priming is taking place and then is contacted by the fluid, builds up pressure, breaks friction with the surface and is driven forward to a position that can be detected by sensor  114  or the operator. The component could also be floating balls which rise and fall relative to the presence and the density of the fluid present, discussed in detail herein with regard to positioning such balls in the syringe. 
     H. Capacitance Measurement based on Swell and Stretch of at least a Portion of the Syringe 
     Capacitance is defined as the change in volume of a fluid path element, elements, or the whole system as a result of a change in pressure on the system, for example when the internal pressure of the system is increased by operation of the plunger to pressurize the system during an injection process. Total system expansion volume, capacity, or capacitance volume represents the total amount or volume of suppressed fluid (i.e., backflow volume) that is captured in the swelling of the injector system components due to the applied pressure. Total system capacitance and capacitance volume is inherent to each fluid injection system and depends on a plurality of factors, including injector construction, mechanical properties of materials used to construct the syringe, piston, pressure jacket surrounding the syringe, pressure jacket and restraint movement or flexing, fluid density, compressibility, and/or viscosity, change in flow volume under constant pressure, fluid lines delivering the contrast and saline to a flow mixing device, the starting pressure, the ending pressure, etc. For example, in dual syringe injectors, the amount of back or reverse flow increases when the relative speed difference between the two pistons of the injection system is large and the pressure required is high, which can occur when the simultaneous fluid flow is through a small restriction, the speed of the total fluid injection is large, and/or the viscosity of the fluid is high. The back or reverse flow can prevent different ratios of simultaneously delivered fluid from ever occurring in certain injections, which can be a detriment for all two-syringe type injector systems, such as fluid injector  10 . 
     Capacitance measurement can be used to correct for changed flow rate and volume delivered dynamically to enhance clinical imaging practices. More specifically, in medical procedures, such as in the intravenous infusion of a contrast medium for contrast-enhanced radiographic imaging, it is often desirable to introduce a “sharp bolus” of fluid in which the medication and/or diagnostic fluid is introduced at increased pressure for rapid delivery into a specific location within the body. In the case of contrast-enhanced radiographic imaging, sufficient contrast media must be present at the specific location or region of interest in the body at a predetermined time for diagnostic quality images to be taken during the procedure. Therefore, accuracy in the amount or volume of contrast media delivered to the patient and the time at which this volume of contrast media reaches a particularly point in the body of a patient is important. A “sharp bolus” of contrast media in practice may be defined as a distinct or defined column of liquid having well-defined opposing ends or boundaries. Accordingly, accuracy in the amount of fluid delivered intravenously to a patient is often of importance in medical therapeutic and diagnostic procedures and such accuracy can be diminished by capacitance volume expansion of the fluid delivery path components when the fluid delivery system is under pressure. Further details of capacitance measurement and capacitance correction is described in U.S. Pat. No. 8,403,909 to Spohn et al., which is hereby incorporated by reference in its entirety. 
     With reference to  FIG. 47 , as a fluid is delivered portions, of the syringe  12  will swell and stretch due to increase in internal pressure during an injection procedure. According to aspects of the present disclosure, the capacitance volume can then be determined as follows. This swell and stretch can be detected real-time by the at least one sensor  114  and the extent thereof can be measured using the image processing software provided on the central processing unit  116 . For instance, the outside diameter of the syringe  12  along the length of the barrel  18  of the syringe  12  can be determined as shown in  FIG. 47 . The central processing unit  116  can then integrate across the different outer diameter measurements along the length of the barrel  18  above the bottom seal of the plunger  26  to determine an accurate volume within the syringe  12  dynamically. Thereafter, the expected volume if the syringe  12  had no capacitance is subtracted from the determined dynamic volume and this results in a remaining volume which corresponds to the capacitance volume. Once a capacitance volume is known, fluid injector  10  can be controlled to control piston  124  to compensate for expansion of barrel  18  under pressure ensuring delivery of a sharp bolus. 
     With reference to  FIG. 48 , a volume versus time graph of an injection procedure performed by fluid injector  10  is illustrated in which line  501  represents a volume of fluid the fluid injector  10  has been programmed to believe has been delivered absent any correction for capacitance; line  503  represents the volume of the fluid that has actually been delivered to the patient; and line  505  represents the difference due to system capacitance between what is believed to have been delivered and what has actually been delivered. The scanner (not shown) used to capture an image for diagnostic purposes is activated and instructed to start capturing images at the exact time interval the drug is expected to be passing through the particular part of the body that is desired to be imaged. That time is based on the amount of fluid the fluid injector  10  believes is being introduced over a certain period of time (i.e., line  501  in  FIG. 48 ). Since the actual amount of fluid is delivered later than expected, the scanner may in certain instances capture images when the fluid (i.e., contrast) is not fully introduced into the part of the body being imaged. This is due to the capacitance, or swelling of the syringe and tube set with pressure as described herein. To correct for this, most operators introduce an estimated delay to try to compensate for capacitance. However, by determining the flow rate and the capacitance based on swell and stretch sections as described herein, the controller of the fluid injector  10  can automate this delay for the operator and capture the best quality images for diagnostic purposes. 
     I. Determination of Volume Remaining 
     In one example, the fluid verification system  110  may be arranged such that the at least one sensor  114  can capture an image of the syringe  12  that includes the syringe barrel  18  and the plunger  26  such that a position of the plunger  26  in each of the images can be determined. Based on these images, the volume of contrast or saline remaining within the syringe  12  can be determined. Specifically, with reference to  FIG. 49 , an image of the syringe  12  is obtained by the sensor  114  at step  570 . Then, at step  572 , the image processing software identifies the plunger  26  in the image by using pattern recognition based on a training image as discussed herein. Next, at step  574 , the image processing software determines the position of the plunger  26  within the barrel  18  of the syringe  12  by determining the change in location of the plunger  26  relative to a reference point. Once the position of the plunger  26  within the barrel  18  of the syringe  12  has been determined, this position can be compared to known positions corresponding to a volume of fluid remaining within the syringe  12  at step  576 . The central processing unit  116  then sends a signal to display the volume remaining to the display  118  at step  578 . The volume remaining may be displayed as a numerical value or a graphical representation of the syringe  12  may be displayed that illustrates the real-time volume remaining within the syringe. Images are continuously taken and the display of volume remaining is continuously updated until the injection procedure is complete as determined at step  580 . Correction of remaining syringe volume by measurement of syringe expansion during injection due to capacitance may also be incorporated into the protocol. Accordingly, the at least one sensor may measure the change in outer diameter of the syringe, for example by comparison of an image to a reference template, and calculate the volume due to capacitance. This capacitance volume may be monitored real-time and transmitted to the central processing unit where algorithmic analysis may allow compensation for capacitance to adjust the fluid delivery and provide for delivery of a sharp bolus. 
     In an alternative example, the volume remaining in the syringe  12  can be determined using only an image of the halo  120  if the plunger  26  of  FIGS. 5A and 5B  is utilized. More specifically, the plunger  26  can be formed from or coated with a reflective material having a plurality of different colored stripes  38 . The reflective material forming the stripes  38  reflect light directed toward the plunger  26  in the distal direction through the syringe barrel  18  to produce the halo. As the plunger or plunger cover  26  moves through the barrel, light reflects from a different stripe  38  depending on the position of the plunger  26  within the syringe barrel  18 . Since each of the stripes  38  of the plunger  26  is different in color, the color and/or appearance of the halo changes depending on the stripe  38  upon which the light is reflected as the plunger  26  advances or retracts through the syringe barrel  18  during an injection or filing procedure. The at least one sensor  114  may be positioned to capture images of the halo as the plunger advances or retracts through the syringe barrel  18 . The image processing software provided on the central processing unit  116  detects the change in color of the halo. The central processing unit is configured to then determine a position of the plunger  26  within the syringe barrel  18  based on the color of the halo. Once the central processing unit  116  determines the position of the plunger  26 , the volume of fluid remaining within the syringe is determined. The central processing unit  116  then sends a signal to display the volume of fluid remaining on the display  116 . The volume of fluid remaining may be displayed as a numerical value or a graphical representation of syringe  12  may be displayed that illustrates the volume remaining within the syringe. In an alternative embodiment, different colored LED lights may be located in the piston to transmit light through a translucent/transparent plunger material in similar concentric circles on the plunger. 
     J. Pressure Feedback based on Swell and Stretch of the Syringe 
     In another example, image processing techniques may be utilized to determine the pressure at which a fluid within the syringe  12  is being delivered to a patient during a fluid injection procedure due to the fact that portions, such as a portion of the distal end  24 , of the syringe  12  will swell and stretch during an injection procedure. The extent of this swell and stretch may correspond to the pressure that the fluid exerts within the syringe at a given time. 
     With reference to  FIGS. 50 and 51 , according to one embodiment, in order to enhance this swell and stretch, an alternative example of the syringe  12  having a flexible section  590  positioned at a distal end  24  thereof may be utilized. Many components of the syringe  12  shown in  FIGS. 50 and 51  are substantially similar to the components of the syringe  12  described herein with reference to  FIG. 2 . Reference numerals in  FIGS. 50 and 51  are used to illustrate identical components as the corresponding reference numerals in  FIG. 2 . As the previous discussion regarding the syringe  12  generally shown in  FIG. 2  is applicable to the aspect shown in  FIGS. 50 and 51 , only the relevant differences between these systems are discussed herein. 
     In one aspect, the flexible section  590  may be configured to expand when the internal pressure of the syringe  12  increases during an injection procedure. The flexible section  590  may be insert molded from a more flexible material than the syringe barrel  18 . The material forming the flexible section  590  may be any suitable flexible material such as, but not limited to TPU, TPE, polypropylene, polyethylene, and, thermoplastic elastomers. In addition, flexible material  590  may be a transparent or translucent material which when illuminated with electromagnetic radiation source  112  shows a halo feature described herein. 
     While the flexible section  590  is illustrated in  FIGS. 50 and 51  as being positioned at the distal end  24  of the syringe  12 , this is not to be construed as limiting the present disclosure, as flexible section  590  may be applied to many areas of syringe  12 . Factors to consider include minimizing fluid capacitance while maximizing swell for better pressure resolution. 
     With reference to  FIGS. 52 and 53  and continued reference to  FIGS. 50 and 51 , the fluid verification system  110  comprising the at least one sensor  114 , central processing unit  116 , and display  118  according to this aspect may be positioned such that the sensor  114  is capable of capturing an image of the flexible section  590  during an injection procedure. Once an image of the flexible section  590  is obtained, the image processing software of the central processing unit  116  measures an increased diameter of the flexible section  590  and correlates the increased diameter with syringe internal pressure. For example,  FIG. 52  illustrates the flexible section  590  having a small increase in diameter that corresponds to a small syringe internal pressure while  FIG. 53  illustrates the flexible section  590  having a large increase in diameter that corresponds to a large syringe internal pressure. Central processing unit  116  may display this syringe internal pressure on display  118  and control fluid injector  10  to allow active pressure control within the syringe during injections. 
     Accordingly, the flexible section  590  provides a “live” or real-time readout on pressure within the barrel  18  of the syringe  12  during an injection procedure. With reference to  FIG. 54 , the negative pressure created during a filling procedure causes the flexible section  590  to move inward. The dimensional changes of the flexible section  590  can be measured using the sensor  114  and image processing software provided on the central processing unit  116  and the subsequent vacuum level can thereafter be determined. 
     Such negative pressure may be important to the rolling diaphragm syringe  135  described herein because having a high vacuum level during a fill of such syringe  135  could crush or deform the walls of the syringe  135 . Accordingly, with reference to  FIG. 55 , one embodiment of the rolling diaphragm syringe  135  may be adapted to include a flexible section or diaphragm  591  on a connector  592  attached to the distal end  137  of the rolling diaphragm syringe  135  or provided in the cap  390  (not shown). The outer diameter of the flexible section  591  can be measured dynamically in real-time using the at least one sensor  114  and image processing software provided on the central processing unit  116  as described herein with regard to the measurement of the diameter of the flexible section  590 . The outside diameter of the flexible section  591  decreases as the vacuum within the rolling diaphragm syringe increases during a filling procedure. Therefore, the size of the outside diameter of the flexible section  591  can be used to determine the vacuum level within the rolling diaphragm syringe  135 . Thereafter, vacuum level can be maintained under a specified threshold by adjusting the rate at which piston  138  is withdrawn to prevent crushing of the rolling diaphragm syringe  135 . 
     With reference to  FIGS. 56A and 56B , according to an aspect, a determination of the pressure within the syringe  12  can also be obtained by positioning the electromagnetic radiation source  212  such that it reflects through at least a portion of a sidewall of the syringe barrel  18 . Light that shines through the sidewall of the syringe barrel  18  is visualized at the bottom of the halo  120  as shown by the lines  121   a  and  121   b.  For example, if there is no light shining up the sidewall of the syringe barrel  18 , this area will appear as a black line ( 121   b ). Placing the electromagnetic radiation source  212  underneath the syringe  12  facing up towards the sidewall of the syringe barrel  18  causes the line at the bottom of the halo  120  to appear lit up (see element  121   a  in  FIG. 56A ) because the light travels up the interior of the sidewall of the syringe barrel  18  and is portrayed in the halo  120 . 
     As the syringe  12  is subjected to pressure for example during an injection procedure, it swells, pushing the walls of the syringe  12  outward as shown in  FIG. 56B . This removes the straight-line path for the light from the electromagnetic radiation source  212  to the bottom of the halo  120 . This line fades from light to dark as the syringe  12  swells (i.e., pressure increased) (see element  121   b  in  FIG. 56B ). The electromagnetic radiation source  212  may also be placed such that the light would completely disappear when the pressure limit of the syringe was reached (i.e., the syringe swells enough to block the light). 
     Alternatively the brightness could be determined as a function of pressure (i.e., swelling) and be used to determine pressure. For example, image recognition software may be used to monitor change in intensity of the line to provide real-time feedback on syringe capacitance. 
     K. Flow Rate Feedback 
     Feedback regarding the flow rate of the fluid delivered by the fluid injector could also be provided to an operator using many of the concepts described herein. More specifically, the position of the plunger  26  axially within the syringe barrel  18  can be monitored by the sensor  114  and the image processing software during an injection procedure. Thereafter, a curve can be created showing the position of the plunger relative to the time during the injection procedure. An equation to fit the curve can then be derived. The equation is then provided to a logic algorithm in which the data from the curve is embodied to calculate the flow rate of fluid being delivered by the injector. This flow rate can be displayed to the operator on display  118 . 
     L. Syringe Filling Feedback 
     When filling the syringe  12 , with contrast or saline, it has been observed that the halo or illuminated identification pattern  120  described in detail herein is only present if the syringe is being filled at a proper rate. For example, using a syringe such as the syringe  12 , the proper fill rate is 4 mL/sec this is the fastest fill rate with the thickest fluid that can be achieved before a vacuum head is drawn into the syringe. However, the fastest specified fill rate will depend upon the particular restrictions of the fluid injection system at issue. The piston should be drawn back such that the syringe is filled in the fastest possible manner depending on the fluid injection system that is being utilized. This is accomplished using the concepts described herein by dynamically examining the halo  120  using the sensor  114  and the image processing software provided on the central processing unit  116  during a filling procedure. As long as the halo  120  is determined to be completely present then the vacuum has not reached a threshold where a vacuum head (i.e., air) is generated in the syringe. The halo  120  is recognized using the sensor  114  and the image processing software provided on the central processing unit  116  as described herein and the position of the top edge of the halo  120  relative to the bottom edge of the halo  120  is detected. If the top edge of the halo  120  begins to move downward, an indication that air is being pulled into the syringe  12  can be provided to the operator. In addition, the fluid injector  10  can be controlled to adjust the rate at which the piston  124  is drawing the plunger  26  back to reestablish the appropriate size of the halo  120 . This allows the fluid injector  10  to achieve the fastest possible fill rate independent of the size of the syringe, the fluid type, or the fill rate. 
     In other words, if the syringe is being filled too fast, which leads to air being introduced into the syringe, the halo  120  will not be present. Accordingly, the sensor  114  can be positioned to capture an image of the halo  120  during a filling procedure. The image processing software of the central processing unit  116  processes the image to determine the presence of the halo  120 . If an absence of the halo  120  results, a signal is sent to the fluid injector  10  to stop the filling process and adjust the rate at which the piston rod  124  retracts the plunger  26  so that the halo  120  is present throughout the filling process. 
     M. Other features of the syringe that may be identified with image processing 
     Several other features of the syringe  12  may be imaged using the fluid verification system  110  and information obtained thereby may be provided to the fluid injector  10 . For example, it is often necessary for the operator or technician to validate the syringe prior to performing the injection. Validation may include confirming that the syringe is acceptable for the injector and determining various characteristics of the syringe and fluid contained therein. For example, the operator must verify that identifying information, such as the syringe dimensions (e.g., diameter, length, and fluid volume), and fluid contents are correct for the procedure being performed. In addition, the operator may be required to provide certain information about the syringe, such as the date of manufacture, source, frictional characteristics between the plunger and syringe barrel, fluid viscosity, and the like (referred to generally herein as “syringe injection parameters”) to the fluid injector or the injector operating system to control piston force and acceleration to deliver fluid at a desired flow rate. The identifying information may be contained on or associated with a machine readable identification tag, such as a barcode. Accordingly, an image of such a barcode may be obtained by the sensor  114 . The image processing software provided on the central processing unit  116  may then be configured to read the identifying information from the barcode and provide this information to the fluid injector  10 . In certain examples, the barcode may be backlit by the electromagnetic radiation source  112 , thereby making it more clearly visible to the sensor  114 . 
     In addition, the cylindrical syringe barrel  18  is, in effect, a lens itself. Utilizing the curvature of the barrel wall, images that are captured and recognized appear different to the image processing software provided on the central processing unit  116  if there is air in the syringe  12  or if fluid is present in the syringe  12 . If there is air in the syringe  12 , the image of the barcode received by the sensor  114  appears in a first size and/or orientation. If there is fluid present in the syringe  114 , the image of the barcode appears in a second size and is inverted. Accordingly, in one example, the barcode may be encoded with information such that when it is read by the sensor  114  when there is air in the syringe  12 , the code informs the system that the syringe  12  is present, the size of the syringe  12 , and that air is present in the syringe  12 . When fluid is present within the syringe  12 , the barcode image inverts and the image processing software provided on the central processing unit  116  recognizes the new code which provides a signal to the system indicating that fluid is present within the syringe  12 . Furthermore, the relative size of the barcode provides an indication of the fluid type within the syringe  12  (i.e., saline, contrast, or the type of contrast). 
     In another example, with reference to  FIG. 57 , a temperature strip  58  may be added to the syringe  12  to provide an indication of the temperature of the contents of the syringe  12  to an operator. This temperature strip  58  may be imaged by the sensor  114  and automatically read by the image processing software. Specifically, the sensor  114  is positioned to capture an image of the temperature strip  58  on the syringe barrel  18 . The temperature strip  58  is configured to change color with temperature or have some other method that indicates the temperature. The image processing software is configured to detect this change in color and determine the temperature based on the change in color. Thereafter, the temperature information may be provided to the fluid injector. In certain examples, temperature strip and barcode may both be provided on a label applied to the syringe  12 . 
     N. Exemplary Fluid Injection System Utilizing Image Recognition Techniques 
     With reference to  FIGS. 58-60 , an exemplary fluid injection system  600  comprises a fluid injector  10  that may have a housing  14  formed from a suitable structural material, such as plastic, a composite material, and/or metal. The housing  14  may be of various shapes and sizes depending on the desired application. For example, the fluid injection system  600  may be a freestanding structure having a support portion  70  connected to a base  72  with one or more rollers or wheels such that the fluid injector  10  is movable over the floor. The fluid injector  10  may include at least one syringe port  16  for releasably connecting the at least one syringe  12  to respective piston rods  124 . In various examples, the at least one syringe includes at least one syringe retaining member configured for retaining the syringe within the syringe port  16  of the fluid injector  10 . In non-limiting examples, the at least one syringe retaining member is configured to operatively engage a locking mechanism provided on or in the syringe port  16  of the fluid injector  10  to facilitate self-oriented loading and/or removal of the syringe to and from the injector  10 . The syringe retaining member and the locking mechanism together define a connection interface for connecting the syringe to the fluid injector  10 . An example of various connection interfaces is described in U.S. Pat. No. 9,173,995. 
     In certain non-limiting examples, it is desirable to temporarily rotate and/or invert the injector housing  14  including syringe ports between a substantially vertical position (i.e., with the syringe port(s) pointing upwards), which may facilitate, for example, the loading of a syringe into a syringe port or the filling of a syringe with medical fluid, and an inverted position, which may facilitate, for example, the removal of air bubbles in a medical fluid contained within a syringe, or the conducting of an injection procedure. Accordingly, in non-limiting examples, housing  14  may be connected to support portion  70  in a rotatable fashion such that housing  14  is rotatable relative to the support portion  70  and retractable pole  74 . 
     The fluid injection system  600  may further include a lower support member  76  that may be extended or retracted in a vertical direction to adjust the height of the fluid injector  10 . An operator may push down on a handle  78  to release a locking connection between the lower support member  76  and a fluid warmer  80  provided on the lower support member  76 . As the handle  78  is pressed down, the operator can lift or lower the fluid warmer  80  to adjust the height of the fluid injector  10 . 
     In non-limiting examples, at least one fluid path set  17  may be fluidly connected with the distal end of the at least one syringe for delivering medical fluid from the at least one syringe to a catheter, needle, or other fluid delivery connection (not shown) inserted into a patient at a vascular access site. Fluid flow from the at least one syringe may be regulated by a fluid control module operated by a controller, such as a detachable touch screen controller  82  or any suitable device. The fluid control module may operate various pistons, valves, and/or flow regulating devices to regulate the delivery of the medical fluid, such as saline and contrast, to the patient based on one or more user selected injection parameters, such as injection flow rate, duration, total injection volume, and/or ratio of contrast media and saline. 
     The controller  82  may include one or more processors, memory, network interfaces, and/or the like and may be configured to control a display comprising a graphical user interface (“GUI”), which may allow a user to view and/or interact with various injection parameters through graphical icons and visual indicators produced on the display. The controller  82  may include the central processing unit  116  having the image processing software provided thereon or on a separate unit. In non-limiting examples, the controller  82  may be formed as a detachable touch screen controller. The controller  82  may also be non-removably attached to the fluid injector  10 . The controller  82  may be used to monitor one or more injection parameters, including, for example, patient specific information (age, weight, sex, organ to be imaged, dosage of imaging agent, etc.), which may be inputted by the user or recalled/downloaded from a database, a network, a memory, or another controller in communication with the system by a wired or wireless communication process. The controller  82  may be further configured to control various injection parameters which may be inputted by a user and/or calculated by one or more algorithmic calculations performed by the controller  82 , the fluid control device, and/or another controller or processor in communication with the fluid control device and/or the controller  82  based on data downloaded from a database and/or inputted by a user. 
     With specific reference to  FIGS. 59 and 60 , the exemplary fluid injection system  600  utilizes the illuminated identification pattern and image processing techniques discussed herein. As described above, the system  600  includes a fluid injector  10  similar to the fluid injector described with reference to  FIG. 1 . The fluid injector  10  is configured to engage a pair of syringes  12 . The syringes  12  are mounted to syringe ports  16  of the fluid injector  10 . A number of electromagnetic radiation sources  112 , such as LEDs, are mounted to or embedded in a distal end of a piston rod  124  of the injector  10 . The LEDs are configured to illuminate in a first color when a first fluid is detected within the syringe  12  and a second color when a second fluid is detected within the syringe  12 . When actuated, the piston rod  124  advances toward and is received within the cavity (not shown) defined by the plunger  26 . The LEDs emit light in the axial direction through the plunger cover  26  for producing the halo  120  adjacent to the distal end  24  of the syringe barrel  18  in the manner discussed above. The sensor  114  may be removably provided on a support portion  602  of the fluid injection system  600  such that the sensor  114  is positioned behind the syringes  12  when the syringes  12  are being filled with fluid from a multi-dose fluid bottle or bag. As described herein, the fluid injection system  600  may be configured to identify the type of fluid that is directed into the syringe  12  or the fluid level in each syringe  12  using image processing techniques. Based on the information identified by the imagining processing techniques, the injector  10  may adjust its operating parameters to achieve desired filling and injection parameters. 
     As discussed herein, the electromagnetic radiation source  112  may be a light bulb, LED bulb, visible light emitter, infrared emitter, or laser, positioned to project an electromagnetic radiation beam through an interior of the syringe  12 . The electromagnetic radiation source emits electromagnetic radiation generally in an axial direction through the syringe  12 . For example, an electromagnetic radiation beam may pass through a translucent or transparent plunger or plunger cover  26  and toward the distal end  24  of the syringe  12 . 
     As discussed in greater detail herein, the electromagnetic radiation source  112  can be configured to increase conspicuousness of the halo  120  or to tailor the halo  120  for particular sensors or electromagnetic radiation detectors. In one example, the electromagnetic radiation source  112  includes a laser having a wavelength of about 532 nm (e.g., a green laser). The green laser electromagnetic radiation source can be used with neutral colored or transparent plungers and still produce a conspicuous colored halo. In other examples, the electromagnetic radiation source  112  can emit electromagnetic radiation outside the visible spectrum provided that the system includes a sensor or camera capable of detecting radiation (e.g., the halo) within the emitted wavelength. In one such aspect, an infrared sensor may be provided to detect the radiation on the syringe  12 . In still other examples, the electromagnetic radiation source can be configured to emit polarized light or certain wavelengths of filtered light, which can be more easily distinguished from ambient light. In other examples, the electromagnetic radiation source can be configured to emit pulses of light according to a predetermined and identifiable sequence, which can be identified by a system operator or automatically detected by a sensor. 
     Light or electromagnetic radiation passing through the plunger or plunger cover  26  substantially radiates through the syringe  12  to form the halo  120 . When the syringe  12  is empty or only partially filled, the electromagnetic radiation beams pass through the syringe  12 , but do not form a distinctive illuminated portion or halo near the distal end thereof as shown in  FIG. 8 . In contrast, when the syringe  12  is entirely filled with fluid, the electromagnetic radiation beams are refracted by the fluid, which produces a halo  120  near the distal end  24  of the syringe  12 . A system operator or automated image reading or optical device, such as sensor  114 , can identify whether the halo, if present, is the correct shape and size. If the halo is too small, not bright enough, or not present at all, the system operator can add additional fluid to the syringe  12  for complete filling. If a halo having the correct size, shape, and brightness is identified, then verification is complete and the fluid contents of the syringe  12  are ready for administration to a patient. 
     In certain examples, the system  600  is also capable of, through the use of image recognition, determining whether two syringes  12  are present on the fluid injector  10  simultaneously. In addition, the system  600  detects whether the syringes  12  are filled with fluid or air. The system  600  also, using images obtained from sensor  114 , visualizes features on the syringe barrel  18 , visualizes height differences of the halo  120 , or visualizes laser light passing through the fluid to detect which of the two syringes  12  has contrast and which has saline as described in greater detail herein. Once this has been determined, the system  600  can send a signal to the electromagnetic radiation source  112  positioned on the piston rod  124  underneath the translucent plungers on the injector head. This signal can alert the electromagnetic radiation source to light up the LEDs in a first color, such as green, underneath syringe  12  determined to have contrast, and light up the LEDs in a second color, such as blue, underneath syringe  12  determined to have saline. This light will illuminate halo  120  to have a color corresponding to that of the LEDs, for visualization by the operator. 
     The system can also send a signal to alert the operator of the type of fluid via any other method of visual, auditory, or sensory cues. For instance, once it has been determined by image recognition techniques that a syringe  12  contains contrast, visual cues (LEDs, laser light, graphics, and/or text) and/or auditory cues (alarms, bells, whistles, other sounds) alerts the operator to the fact that a particular syringe  12  contains contrast. For example, green overlay features may be used for the side of the injector  10  specified for contrast. Green LEDs can be used to illuminate the halo  120  on the syringe  12  that has been determined to have contrast, regardless of which side the syringe  12  is on. This will be achieved by having circuits of both LED colors (green and blue) where the green will be illuminated if contrast is determined to be present and blue if saline is determined to be present. It is also possible to send messages to the operator in the control room alerting them to which syringe is on which side, and whether that conflicts with the protocol prescribed by the attending physician. 
     With specific reference to  FIG. 59 , the system  600  has determined that a contrast syringe  12   a  is installed at right and a saline syringe  12   b  at left as shown. On the display  118 , “C” is displayed at right and “S” at left to indicate that the image processing software of the central processing unit  116  has identified contents of syringe at left as saline and contents of syringe at right as contrast. With reference to  FIG. 61 , the contrast syringe  12   a  has been moved to the left position and saline syringe  12   b  to the right position as shown. On the display  118 , “C” is now displayed at the left and “S” is now displayed at the right to indicate that the image processing software of the central processing unit  116  has identified contents of syringe at left as contrast and contents of syringe at right as saline. With reference to  FIG. 62 , the fluid injector  10  is shown with the syringes  12   a,    12   b  absent. On the display  118 , “A” is now displayed at both left and right to indicate that the image processing software of the central processing unit  116  has identified air present at both locations. With reference to  FIG. 63 , an empty syringe  12  has been installed at the left position and another empty syringe  12  has been installed at right position as shown. On the display  118 , “A” is now displayed at both left and right to indicate that the image processing software of the central processing unit  116  has identified air present in both syringes. 
     O. Utilizing a Syringe with Floating Elements 
     With reference to  FIG. 64 , another alternative example of a syringe  12  that may be used with fluid injector  10  and fluid verification system  110  to determine the type of fluid within the syringe  12  is illustrated. This syringe  12  is similar to the syringe  12  of  FIG. 2  except that it includes a plurality of objects, such as floating balls  650   a,    650   b,  and  650   c , positioned between the distal end  24  of the syringe  12  and the plunger. The density of the balls  650   a,    650   b,  and  650   c  are different to allow the ball  650   b  to float in saline (density equal to or less than 1.0 g/ml) and the ball  650   c  to sink in saline but float in contrast (density greater than 1.1 g/ml but less than least dense contrast). 
     The floating balls  650   a,    650   b,  and  650   c  for contrast and saline differentiation operate based on the principle of buoyancy. This is an upward force on an object in fluid opposing its weight downward. The driving variable of this phenomenon is density, specifically of the fluid and of the weight immersed in the fluid. If the density of the balls  650   a,    650   b,  and  650   c  is greater than that of the fluid by enough margin, the weight overcomes the buoyant force and the balls  650   a,    650   b,    650   c  sink to the bottom. If the density of the balls  650   a,    650   b,    650   c  is less by enough margin, the ball  650   a,    650   b,    650   c  float. 
     Saline and contrast have different densities. For example, saline may have a density around 1 g/mL, while the thicker contrasts have densities around 17 g/mL). In one example, ball  650   b  has a density of 0.5 g/mL and ball  650   c  has a density of 5 g/mL. With reference to  FIG. 65 , when the syringe  12  is full of air and positioned upright all of the floating balls  650   a,    650   b,  and  650   c  sit at the bottom of the syringe  12  due to gravity. Accordingly, a syringe  12  filled with air has no balls floating near the distal end  24  thereof. With reference to  FIG. 66 , when the syringe  12  is filled with saline, based on the principle described above, the ball of density 0.5 g/mL (i.e., ball  650   b ) floats to the distal end  24  of the syringe  12 , while the ball of density 5 g/mL (ball  650   c ) remains at the bottom as the buoyant force does not overcome its weight. A reference ball  650   a  may also be positioned within the syringe  12  having a density of less than 0.5 g/mL. This ball  650   a  also floats to the distal end  24  of the syringe  12  when saline is present within the syringe  12 . Accordingly, a syringe  12  filled with saline has two balls floating near the distal end  24  thereof. With reference to  FIG. 67 , when syringe  12  is filled with contrast of density 17 g/mL, all three balls  650   a,    650   b,    650   c  float to the top as each ball has a density less than the fluid in which they are immersed. 
     With continued reference to  FIGS. 65-67 , the sensor  114  may be positioned to capture an image of the distal end  24  of the syringe  12 . Thereafter, the image processing software on the central processing unit  116  can detect the presence or absence of the balls  650   a,    650   b,  and  650   c  in the image. If the image processing software on the central processing unit  116  determines that no balls are present, a signal can be sent to the display  118  to display that air is present within the syringe  12 . If the image processing software on the central processing unit  116  determines that balls  650   a  and  650   b  are present, a signal can be sent to the display  118  to display that saline is present within the syringe  12 . Finally, if the image processing software on the central processing unit  116  determines that all three balls are present, a signal can be sent to the display  118  to display that contrast is present within the syringe. This principle works for any number of balls in the syringe as long as they have the proper corresponding densities. A more in-depth application is having several different balls of varying densities that correspond to the varying densities of different brands and concentrations of contrast. This principle can then be used to determine the different types of contrast present using image recognition of floating balls. In addition, the balls  650   a,    650   b , and  650   c  may have different sizes to provide another characteristic to allow the image processing software to differentiate between contrast and saline. 
     The syringe  12  of  FIG. 64  may also be utilized to determine a temperature of a fluid contained within the syringe  12 . The floating balls  650   a,    650   b,  and  650   c  for temperature determination again operate based on the principle of buoyancy. This is an upward force on an object in fluid opposing its weight downward. The driving variable of this phenomenon is density, specifically of the fluid and of the weight immersed in the fluid. If the density of the balls  650   a,    650   b,  and  650   c  is greater than that of the fluid by enough margin, the weight overcomes the buoyant force and the balls  650   a,    650   b,  and  650   c  sink to the bottom. If the density of the balls  650   a,    650   b,  and  650   c  is less by enough margin, the balls float. In this application, density changes with temperature. As a fluid contained within the syringe  12  is heated, its volume tends to increase which decreases its density. Accordingly, the floating balls  650   a,    650   b,  and  650   c  may have incremental densities (e.g., 0.5 g/mL, 0.6 g/mL, 0.7 g/mL for saline and 15 g/mL, 15.5 g/mL, 16 g/mL for contrast) so that as the temperature of the fluid is increased, the corresponding decrease in density will cause specific balls  650   a,    650   b,  and  650   c  to either float or sink. The distal end  24  of the syringe  12  may be imaged using the sensor  114  and the image processing software on the central processing unit  116  can determine the number of balls present in the image. Once the number of balls is determined, the central processing unit  116  can correlate the number of balls to the temperature of the fluid. The diameter of the balls  650   a,    650   b,  and  650   c  may also be varied to correspond with their density/temperature relationship so that the image processing software on the central processing unit  116  can measure the diameter and correlate that to a density and from the density to a temperature of the fluid. 
     The syringe  12  of  FIG. 64  may also be utilized as a pressure limiting tool. More specifically, one of the balls  650   a,    650   b,  and  650   c  may be configured to have a lightly positive buoyancy at zero pressure when submerged in a fluid. Accordingly, such a ball floats when the syringe is not injecting fluid and is filled with fluid. As the injection begins, the pressure inside the syringe increases. Since the air in the floating ball is more compressible than the fluid contained within the syringe, the volume of the ball decreases, thereby increasing its density. Therefore, the floating balls can be designed to sink at a particular internal pressure within the syringe. For example, the ball could be designed to drop to the bottom of the syringe at pressures greater than 325 psi. The dropping ball is then captured in images taken by the sensor  114  and detected by the image processing software. A signal is then sent to the fluid injector to limit the pressure of the injection. 
     III. Other Concepts 
     In another example, the source  112  can emit light of a given wavelength and the speed at which the light travels through the syringe can be measured by a detector and processor and is indicative of the type of fluid contained within the syringe  12 . 
     It should be noted that while all of the concepts described herein are described with reference to syringes and fluid injectors, this is not to be construed as limiting the present invention as these concepts may be utilized with any fluid container. For example, these concepts may be utilized in a beverage bottling setting to ensure that each bottle that is manufactured includes the correct volume of liquid and the correct liquid. The bottles may be provided with a colored translucent or transparent bottom and an angled neck. After the bottles are filled, an electromagnetic radiation source is positioned beneath the bottles to provide light through the bottles and generate a halo near the neck of the bottles. This halo can be identified using a sensor and image processing software as described herein. If the halo is absent or an improper size, a signal is generated that the bottle was not properly filled. 
     Although the disclosure has been described in detail for the purpose of illustration based on what is currently considered to be the most practical and preferred embodiments, it is to be understood that such detail is solely for that purpose and that the disclosure is not limited to the disclosed embodiments, but, on the contrary, is intended to cover modifications and equivalent arrangements. For example, it is to be understood that the present disclosure contemplates that, to the extent possible, one or more features of any embodiment can be combined with one or more features of any other embodiment.