Abstract:
The present invention uses a high signal to noise ratio method and apparatus to analyze a characteristic of a biological object, such as blood glucose level. The method and apparatus can also have surgical applications, such as coagulation or ablation of a pattern on a biological object.

Description:
PRIORITY REFERENCE TO PRIOR APPLICATIONS  
       [0001]    This application claims benefit of and incorporates by reference U.S. patent application Ser. No. 60/423,345, entitled “System and Method for Pattern Delivery of Radiation and Glucose Detection,” filed on Nov. 1, 2002, by inventor Brian Yen. 
     
    
     
       TECHNICAL FIELD  
         [0002]    This invention relates generally to radiation delivery and characteristic analysis, and more particularly, but not exclusively, provides a system and method for characteristic analysis using pattern delivery of radiation to a biological object.  
         BACKGROUND  
         [0003]    Diabetes is a disease of the pancreas in which the pancreas produces little or no insulin or when the body does not respond properly to insulin (“insulin resistance”). There is no cure for diabetes and diabetics must generally manage the disease on a daily basis. One aspect of management includes injecting insulin, such as Lantus, multiple times a day or dispensing it continuously via a pump. Improper administration of insulin can lead to severe side effects including hyperglycemia in which blood glucose levels are too high, which can lead to damage to nerves, blood vessels, and other body organs. Improper administration can also lead to hypoglycemia, in which blood glucose levels are too low, which can lead to passing out and even coma in worst case scenarios. Accordingly, as the amount of insulin dispensed needs to be varied based on blood glucose levels, diabetics must frequently monitor their blood glucose levels.  
           [0004]    Conventionally, home glucose monitoring is performed using a glucose blood meter, which yields results within a few minutes. In order to determine a blood glucose level, a person must first prick his or her finger with a small needle to collect a small amount of blood; the blood must then be placed on a test strip and inserted into the glucose test meter, which analyzes the blood for a blood glucose level. A diabetic can then adjust the amount of insulin to be dispensed accordingly.  
           [0005]    A disadvantage of the conventional method of glucose monitoring is that it requires the drawing of blood, which can be painful and inconvenient. Accordingly, as glucose monitoring is extremely important for diabetics because of the risk of side effects, a new glucose monitoring system and method is needed that is non-invasive and pain free.  
         SUMMARY  
         [0006]    Embodiments of the invention provide a system and method for non-invasive monitoring of blood glucose levels. Embodiments of the invention can also be used for the analysis of other properties of biological and/or non-biological objects. Further, embodiments of the invention can be used for pattern delivery of radiation, for example, in cosmetic surgery such as tattoo removal or varicose vein removal.  
           [0007]    In one embodiment of the invention, a method comprises: detecting a pattern on the biological object; emitting radiation onto the detected pattern; collecting at least a portion of radiation that is reflected by the pattern on the object; and analyzing the collected radiation to determine a characteristic of the biological object.  
           [0008]    An apparatus to carry out the method comprises an imaging detector, a mirror, a radiation emitter, a radiation detection assembly, and electronics. The imaging detector is positioned to receive a first type of reflected radiation from the biological object. The mirror is adjustable to reflect radiation onto a pattern on the object. The radiation emitter is capable of emitting radiation of a second type and positioned to emit the second type of radiation onto the mirror. The radiation detection assembly is positioned to receive reflected radiation of the second type from the biological object. The electronics, which is coupled to the imaging detector, radiation emitter, mirror and radiation detection assembly, is capable of identifying a pattern on the object using reflected radiation data from the imaging detector; adjusting the mirror to reflect the second type of radiation onto the identified pattern; and analyzing a characteristic of the object using reflected radiation data from the radiation detection assembly.  
           [0009]    Accordingly, the apparatus and method provide a high signal to noise ratio without the need for high energy levels by using directed radiation, thereby avoiding interference problems.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    Non-limiting and non-exhaustive embodiments of the present invention are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified.  
         [0011]    [0011]FIG. 1 is a depiction of an eye;  
         [0012]    [0012]FIG. 2 is a diagram illustrating a device capable of pattern detection and pattern delivery of radiation;  
         [0013]    [0013]FIG. 3 is a block diagram of the device of FIG. 2;  
         [0014]    [0014]FIG. 4 illustrates a block diagram of the controlling electronics of the device of FIG. 2;  
         [0015]    [0015]FIG. 5 is a block diagram illustrating the persistent memory of the device of FIG. 2; and  
         [0016]    [0016]FIG. 6 is a flowchart illustrating a method of pattern delivery of radiation and analysis based on reflected radiation.  
     
    
     DETAILED DESCRIPTION  
       [0017]    The following description is provided to enable any person having ordinary skill in the art to make and use the invention, and is provided in the context of a particular application and its requirements. Various modifications to the embodiments will be readily apparent to those of ordinary skill in the art, and the principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles, features and teachings disclosed herein.  
         [0018]    [0018]FIG. 1 is a depiction of an eye  100 . The eye  100  is approximately 2.5 cm wide by 2.5 cm deep, with a height of 2.3 cm. The outer layer  120  of the eye is called the sclera and the approximately ⅙ of the sclera that is clear and exposed is referred to as the cornea. Extraocular muscles are coupled to the sclera and move the eye  100 . The colored region  110  is the pupil of the eye  100  and is located in a second layer (i.e., choroid) of the eye  100  beneath the sclera  120 . The choroid and the sclera  120  include a plurality of blood vessels, such as blood vessel  130 , that supply blood to different regions of the eye. Generally, the blood vessels in the sclera  120  are the blood vessels in the body that are the most directly exposed to radiation. Accordingly, non-invasive analyte detection via spectrum analysis of blood is most easily and accurately performed using the blood vessels of the eyes. The blood vessels in the sclera  120  generally follow a non-linear path within the sclera and have varying thicknesses.  
         [0019]    [0019]FIG. 2 is a diagram illustrating a device  200  capable of detecting a pattern on the eye  100  and then delivering radiation to the eye  100  that coincides with the pattern. For example, the device  200  can detect the blood vessel  130  and deliver radiation that is coincident with the blood vessel  130  of the eye  100 . In an embodiment of the invention, the device  200  can detect a pattern on any object and then deliver pattern radiation to that object, regardless of whether the object is of biological or non-biological origin. For example, the device  200  can detect the pattern of a grain of wood and then deliver pattern radiation such that the radiation is coincident with that grain of the wood. In an alternative example, the device  200  can detect a stress fracture pattern of an aluminum aircraft wing and deliver pattern radiation to the aluminum skin of the aircraft wing such that it is coincident with the stress fracture pattern. In another embodiment of the invention, the device  200  can deliver radiation that is coincident with an area surrounding or near to the pattern.  
         [0020]    In an embodiment of the invention, the device  200  can also select a pattern or a set of patterns according to preset parameters if the object has a plurality of patterns. For example, the device  200  can select the blood vessel  130  in the eye  100  based on thickness, length, and/or color (e.g., red).  
         [0021]    In another embodiment of the invention, the device  200  determines (e.g., detects and/or measures) characteristics of an object by performing a spectrum analysis of radiation radiated by the pattern, using reflective spectroscopy from reflected radiation from radiation incident on the pattern and/or using transmissive spectroscopy from diffuse radiation on an area surrounding or near the pattern. (Hereinafter, the term “radiated radiation” will refer to reflected radiation, diffuse radiation, and/or other radiation). For example, the device  200  can detect the presence of glucose and/or measure glucose concentrations in the blood vessel  130 . It will be appreciated that the device  200  can collect the radiated radiation as either an absorbance spectrum, an interferogram, or any property associated with the exciting source, such as Raman Scattering, fluorecence, scatter, etc. that would be modified by the presence of the analyte of interest. Other techniques for collecting the radiated radiation may also be used. It will also be appreciated that other chemicals (also referred to as analytes) besides glucose may be detected and/or measured using the device  200 .  
         [0022]    The device  200  comprises an electronics section  200   a  and a hood  200   b.  The electronics section  200   a,  as will be discussed further in conjunction with FIG. 3-FIG. 5, houses electronics for detecting pattern(s) on an object; selecting a pattern on the object if the object includes more than one pattern; delivering radiation to the object that is coincident with the detected and selected pattern (and/or coincident with an area surrounding or near to the object); and detecting and/or measuring at least one characteristic of the object or of the pattern on the object based the radiated radiation. The electronics section  200   a  can also include electronics for coagulating or ablating a detected pattern on an object.  
         [0023]    The hood  200   b  covers the object that radiation is to be applied to. For example, the hood  200   b  can cover the eye  100 . The hood  200   b  can be made of plastic or other suitable material that is impervious to light. Because the hood  200   b  is impervious to light, it prevents unwanted light radiation from interfering with the pattern detection and radiation application functions of the device  200 . The hood  200   b  can be of a rigid structure or a non-rigid structure. An advantage of using a non-rigid structure is that it enables application to a wide variety of objects having varying dimensions. In an embodiment of the invention, the hood  200   b  can be custom made according to facial characteristics of an individual so that the hood  200   b  can securely cover the eye  100  and prevent light radiation from interfering with the pattern detection, radiation delivery, and characteristic detection/measurement functions of the device  200 .  
         [0024]    [0024]FIG. 3 is a block diagram of the device  200 . The electronics section  200   a  includes controlling electronics  300 ; a radiation emitter  310 ; a digital micro-mirror device  320  or other radiation directing device; a low level imaging illuminator  330 ; focusing optics  360 ; a CCD imaging detector  370 ; a beam splitter  380 ; and a return radiation detection assembly  390 , such as a pixilated detector. The controlling electronics  300 , as will be discussed in further detail in conjunction with FIG. 4 and FIG. 5, is communicatively coupled to the radiation emitter  310 ; the digital micro-mirror device  320  (or other radiation directing device); the low level imaging illuminator  330 ; the focusing optics  360 ; the CCD imaging detector  370 ; and the return radiation detection assembly  390 . Further, the controlling electronics  300  controls the radiation emitter  310 ; the digital micro-mirror device  320  (or other radiation directing device); the low level imaging illuminator  330 ; and the focusing optics  360 . In an embodiment of the invention, the controlling electronics  300  detects and/or analyzes at least one characteristic (e.g., glucose concentration) of the object that radiation is being applied to based on radiated radiation received by the return radiation detection assembly  390 .  
         [0025]    The radiation emitter  310  emits structured radiation  340  that is coincident on a pattern detected on an object, such as the blood vessel  130  on the eye  100 . In an embodiment of the invention, the radiation emitter  310  emits radiation that is coincident with an area surrounding or near to the pattern, thereby enabling the use of transmissive spectroscopy with diffuse radiation surrounding the pattern. In an embodiment of the invention, the radiation emitted is in the near infra-red spectrum, e.g. about 700 nm to about 3 microns, and is used for spectrum analysis. In another embodiment of the invention, the radiation is of a different wavelength, e.g., about 800 nm, and is used for ablation or coagulation. It will be appreciated that radiation of other wavelengths may be used according to the application. This radiation is reflected by the digital micro-mirror device  320  (which can be made of or coated with aluminum and/or gold and/or other materials), which is controlled by the controlling electronics  300 , onto the beam splitter  380 , which in turn reflects the radiation through the focusing optics  360  onto a detected pattern on the object (and/or an area surrounding or near to the pattern). It will be appreciated by one of ordinary skill in the art that other techniques may be used for directing radiation emitting by the radiation emitter  310 . In another embodiment of the invention, a different radiation directing device may be used in place of the digital micro-mirror device  320 . For example, a LCD panel may be used to selectively block radiation emitted by the radiation emitter  310 . In another embodiment of the invention, the radiation emitter  310  may itself be the radiation directing device since it can be swivel-mounted to the electronics section  200   a,  thereby enabling the radiation emitter  310  to direct the radiation onto an object without the need for a mirror  320  or other device.  
         [0026]    The low level imaging illuminator  330  emits low level radiation that can be of a different wavelength of the radiation emitted by the radiation emitter  310 . Specifically, in an embodiment of the radiation emitted is outside of the critical detection range of the return radiation detection assembly  390  but within the range detectable by the CCD imaging detector  370 . For example, the illuminator  330  may include a low level green or blue light emitting diode (LED). An example of suitable radiation that the low level imaging illuminator  330  emits is visible radiation have a wavelength of 500 nm. The low level radiation emitted by the illuminator  330  illuminates an object having a pattern on it.  
         [0027]    The controlling electronics  300 , in conjunction with the CCD imaging detector  370 , use the low level radiation that is reflected from the object to detect a pattern on the object. If there is more than one pattern on the object, the controlling electronics  300  can also select a pattern based on pre-set parameters. Based on the detection and selection, the controlling electronics  300  controls movement of the digital micro-mirror device  320  or other radiation directing device such that radiation emitted by the radiation emitter  310  traces the detected selected pattern on the object. In another embodiment of the invention, the controlling electronics directs a radiation directing device such that radiation emitted by the radiation emitter  310  surrounds or is near to the pattern, but substantially not incident on the pattern itself.  
         [0028]    The beam splitter  380  splits radiated radiation  350  into two separate beams. A first beam impacts the return radiation detection assembly  390  and a second beam impacts the CCD imaging detector  370 . As mentioned above, the controlling electronics  300  in conjunction with the CCD imaging detector  370 , use the reflected radiation to determine the location of the pattern and control the digital micro-mirror device  320  so that radiation emitted by the radiation emitter  310  traces the detected pattern and/or an area surrounding or near to the pattern. The controlling electronics  300  uses the radiation received by the return radiation detection assembly  390  to detect a characteristic and/or analyze characteristics, such as analyte concentration, of the object or pattern on the object using spectrum analysis techniques, as will be discussed in further detail in conjunction with FIG. 6. In an embodiment of the invention, the return radiation detection assembly  390  includes a pixilated detector, thereby enabling spatially determining from where the radiated radiation is from (e.g., which part of the blood vessel radiated the radiation  350 ).  
         [0029]    [0029]FIG. 4 illustrates a block diagram of the controlling electronics  300  in an embodiment of the present invention. While other application-specific alternatives might be utilized, it will be presumed for the sake of clarity that the elements comprising the controlling electronics  300  are implemented in hardware, software or some combination thereof by one or more processing systems consistent therewith, unless otherwise indicated.  
         [0030]    The controlling electronics includes a central processing unit (CPU)  405 ; working memory  410 ; persistent memory  420 ; input/output (I/O) interface  430 ; display  440  and input device  450 , all communicatively coupled to each other via system bus  460 . The CPU  405  may include an Intel PENTIUM microprocessor, a Motorola POWER PC microprocessor, or any other processor capable to execute software stored in the persistent memory  420 . The working memory  410  may include random access memory (RAM) or any other type of read/write memory devices or combination of memory devices. The persistent memory  420  may include a hard drive, read only memory (ROM) or any other type of memory device or combination of memory devices that can retain data after the controlling electronics  300  is shut off. The I/O interface  430  is communicatively coupled, via wired or wireless techniques, to the radiation emitter  310 ; the digital micro-mirror device  320 ; the low level imaging illuminator  330 ; the focusing optics  360 ; the CCD imaging detector  370 ; and the return radiation detection assembly  390 . The display  440  may include a liquid crystal display (LCD) or other display device. The input device  450  may include a keypad or other device for inputting data, or a combination of devices for inputting data. In an embodiment of the invention, the controlling electronics  300  also includes a speaker that can emit aural data. The speaker may be in place of or in addition to the display  440 .  
         [0031]    One skilled in the art will recognize that the controlling electronics  300  may also include additional devices, such as network connections, additional memory, additional processors, LANs, input/output lines for transferring information across a hardware channel, the Internet or an intranet, etc. One skilled in the art will also recognize that the programs and data may be received by and stored in the controlling electronics  300  in alternative ways.  
         [0032]    [0032]FIG. 5 is a block diagram illustrating the persistent memory  420 . The persistent memory  420  includes a radiation emitter engine  500 ; a radiation directing engine  510 ; an illuminator engine  520 ; an optics engine  530 ; a pattern selection engine  540 ; a pattern selection parameters file  550 ; a feedback engine  560 ; and an analysis engine  570 . The radiation emitter engine  500  controls the radiation emitter  310  including the wavelength of the radiation emitted in an embodiment in which radiation emitter  310  can emit variable wavelength radiation, and the duration of the radiation emission. The radiation directing engine  510 , in conjunction with the feedback engine  560 , controls the positioning of the digital micro-mirror device  320  or other radiation directing device such that radiation emitted by the radiation emitter  310  traces a detected pattern and/or an area surrounding or near to the detected pattern, such as blood vessel  130 , on an object, such as the eye  100 .  
         [0033]    The illuminator engine  520  controls the functioning of the low level imaging illuminator  330  including the wavelength of the emissions in an embodiment in which the low level imaging illuminator  330  can emit variable wavelengths of radiation, and the duration of the emission. The optics engine  530  controls the focusing optics  360  so that the structured radiation  340  emitted by the radiation emitter  310  is focused on the object, such as the eye  100 . The pattern selection engine  540  selects a pattern illuminated by the low level imaging illuminator  330  and imaged on the CCD imaging detector  370 . The selection is based on parameters stored in the pattern selection parameters file  550 . Examples of parameters could include a pattern within a range of thicknesses and within a range of lengths. It will be appreciated that the parameters can include any number of specifications within pre-specified ranges or having no maximums or minimums.  
         [0034]    The feedback engine  560  determines the position of the selected pattern and sends coordinate information to radiation directing engine  510  so that the radiation directing engine  510  can direct radiation emitted by the radiation emitter  310  onto the pattern and/or an area surrounding or near to the pattern. The feedback engine can perform this determination and sending on a very frequent basis, e.g.,  200  times/second in one embodiment, so that even if the object is moving, the digital micro-mirror device  320  or other radiation directing device can still track the pattern and therefore the radiation emitted by the radiation emitter  310  remains coincident on the pattern and/or an area surrounding or near to the pattern despite the movement.  
         [0035]    The analysis engine  570  detects and/or calculates at least one characteristic of the selected pattern or object based on the radiated radiation  350  received at the return radiation detection assembly  390 . In an embodiment of the invention, the analysis engine  570  uses spectrum analysis to determine the concentration of an analyte within the selected pattern. For example, the analysis engine  570  can use spectrum analysis to determine glucose concentration within the blood vessel  130  of the eye  100 . The analysis engine  570  can use techniques for spectrum analysis of glucose and other analytes that are described in U.S. Pat. No. 6,061,582, which is hereby incorporated by reference. Other patents that disclose techniques relating to optical detection that analysis engine  570  can use include U.S. Pat. Nos. 6,025,597; 6,026,314; 6,028,311; 6,151,522; 6,181,957; 6,188,477; 6,246,893; and 6,276,798, which are hereby incorporated by reference. Other techniques that analysis engine  570  can use are disclosed in various journal articles that are known to one of ordinary skill in the art. For example, the articles “Spectroscopic and Clinical Aspects of Noninvasive Glucose Measurements” by Omar S. Khalil (Clinical Chemistry 45:2, 1999); “Optical Measurement of Glucose Levels in Scattering Media” by Gilwon Yoon et al. (Proceedings of the 20 th  Annual International Conference of the IEEE Engineering in Medicine and Biology Society, Vol. 20, No. 4, 1998); and “Multivariate Determination of Glucose Using NIR Spectra of Human Blood Serum” by Fredric M. Ham et al. (IEEE 1994), which are hereby incorporated by reference, disclose techniques that the analysis engine  570  may use.  
         [0036]    [0036]FIG. 6 is a flowchart illustrating a method  600  of pattern delivery of radiation and analysis based on reflected radiation. First, low level radiation of a first type is emitted ( 610 ). This radiation can be outside the critical detection range, e.g., outside the detection range of the return radiation detector assembly  390 , but within the CCD imaging detector  370  detection range. For example, if the return radiation detector assembly  390  detects NIR radiation, then the low level radiation can include light emitted by a low level green or blue LED. Next, the user is advised ( 615 ) to position the device hood  200   b  over the object, e.g., his or her eye. It will be appreciated that the device hood  200   b  can be placed over any object having a pattern. Further, it will be appreciated that advising ( 615 ) need not be including in method  600 . It will be further appreciated that advising ( 615 ) can be done via aural, visual techniques and/or other techniques (e.g., tactile feedback).  
         [0037]    After advising ( 615 ), a desired location is examined ( 620 ). For example, the sclera or choroid of an eye  100  can be examined ( 620 ) for one or more blood vessels. Next, the desired structure or pattern is identified ( 625 ). If there is a plurality of patterns, the desired pattern can be identified ( 625 ) based on pre-specified parameters, such as thickness, color (e.g., red), and/or length of the pattern. If a pattern is ( 630 ) not identified ( 625 ), then the advising ( 615 ) and examining ( 620 ) is repeated until a suitable pattern is identified ( 625 ).  
         [0038]    After a suitable pattern is identified ( 625 ), radiation of a second type is emitted ( 635 ) and directed ( 640 ) towards the pattern or structure identified ( 625 ). The radiation may include radiation for testing (e.g., spectrum analysis) and/or ablation and/or coagulation and/or other purposes. If the radiation is for a testing application, then the radiation can include NIR radiation. If the radiation is for ablation or coagulation, then the radiation should include higher energy radiation, such as radiation having a wavelength of about 800 nm. The process of examining ( 620 ), identifying ( 625 ) and emitting ( 635 ) is repeated at a frequent rate, such as at 200 times/second such that the radiation tracks any movement of the identified pattern. For example, if eye  100  is moving, the examining ( 620 ), identifying ( 625 ), and emitting ( 635 ) will track the blood vessel  130  and continue to impact radiation onto the blood vessel  130  and/or an area surrounding or near to the blood vessel  130  despite the movement.  
         [0039]    If ( 640 ) this is a coagulation/ablation process, then emission ( 645 ) is continued for a suitable amount of time according to the application. After emission ( 645 ) is complete, the device  200  is turned ( 650 ) off and method  600  ends.  
         [0040]    If ( 640 ) this is a testing application, then radiated radiation from the emitting ( 635 ) is collected ( 655 ) and then filtered ( 660 ) to isolate a specific analyte&#39;s spectrum signature. After filtering ( 660 ), a mathematical model is applied ( 665 ) to the filtered data to determine concentration of the analyte. The result is then completed ( 670 ) and output aurally or visually, e.g., via display  440 . Determining analyte concentration, such as glucose concentration, via spectrum analysis is described in U.S. Pat. No. 6,061,582, which is hereby incorporated by reference. The method  600  then ends.  
         [0041]    The foregoing description of the illustrated embodiments of the present invention is by way of example only, and other variations and modifications of the above-described embodiments and methods are possible in light of the foregoing teaching. For example, embodiments of the invention can be used for purposes other than glucose monitoring. Further, components of this invention may be implemented using a programmed general purpose digital computer, using application specific integrated circuits, or using a network of interconnected conventional components and circuits. Connections may be wired, wireless, modem, etc. The embodiments described herein are not intended to be exhaustive or limiting. The present invention is limited only by the following claims.