Abstract:
A transfer device usable in a system for intraluminal treatment of a selected site in a body of a patient in which the transfer device comprises an integral pump for pressurizing and circulating fluid through a fluid path defined by the transfer device and associated catheter. A removable fluid cartridge is provided including a reservoir from which fluid is drawn by the pump and into which fluid is returned after being circulated through the fluid path. The pump may be a peristaltic pump and the fluid cartridge may include an elongated fluid pick-up having an inlet through which fluid is introduced into the transfer device. The fluid pick-up is sized in length so that the inlet is always submerged in the fluid regardless of the orientation of the transfer device. A removable treatment cartridge having a lumen forming part of the fluid path may also be provided, and a storage sleeve for the treatment cartridge may be of a radiation-blocking material, such as quartz. Further, the treatment cartridge may have a memory for storing and indicating selected information about the treating element.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]    This application claims the benefit of U.S. Provisional Application Ser. No. 60/113,406 filed Dec. 22, 1998. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    The present invention relates generally to an intraluminal radiation system for the delivery of treatment elements by way of a catheter to a selected location within the intraluminal passageways of a patient. More particularly, the present invention relates primarily to an improved transfer device for handling the treatment elements and delivering them to the catheter and an improved catheter assembly.  
           [0003]    Since the late 1970&#39;s balloon angioplasty techniques have become widely used for opening blockages in coronary arteries. Briefly, the enlargement of the artery is achieved by advancing a balloon catheter into a narrowed portion of the artery and inflating the balloon to expand the diameter of the artery, thus opening the artery for greater blood flow. Atherectomy techniques, in which blockages are removed or reduced in size, have also been used to the same end.  
           [0004]    While balloon angioplasty has proved an effective way of opening the coronary arteries, in a significant number of cases the arteries will narrow again at the location where the balloon was expanded, such narrowing being termed restenosis. Restenosis is believed to be caused by formation of scar tissue at the site of the angioplasty that results from the injury to the artery caused by the inflation of the balloon. More recently, intraluminal radiation has been used after angioplasty or atherectomy to treat the affected area of the artery to inhibit cell proliferation and wound healing response and, consequently, help to prevent restenosis. Methods and apparatus for such intraluminal radiation treatment are disclosed in U.S. Pat. No. 5,899,882, and co-pending applications Ser. No. 08/936,058, filed Sep. 23, 1997, and Ser. No. 09/304,752, filed May 4, 1999, all of which are incorporated herein by reference. These applications generally disclose an apparatus comprising a catheter, which is inserted intraluminally into the patient and advanced to the site of the area to be treated, and a transfer device for facilitating either the hydraulic or pneumatic advancement and retrieval of individual radioactive treating elements or “seeds” along the catheter to and from the treatment site.  
           [0005]    As with any device inserted into the vascular system, it must have sufficient integrity to insure that no pieces or elements are separated from or exit the device into the vascular system. This is particularly true for the treating elements which are moved to and from the distal end of the catheter. Additionally, because the device is intended to use radioactive treating elements, there is a heightened need for safety to prevent any unintended exposure of either the patient or the user to radioactivity.  
           [0006]    Actual use of the apparatus described in the above-identified patent and co-pending applications has suggested several areas where the device could be improved to reduce the possibility of having treatment elements escape from the system, thus enhancing patient and user safety.  
           [0007]    Consequently, it is the principal object of the present invention to provide a transfer device and catheter assembly that has additional safeguards to protect the patient and user for unintended exposure to radiation.  
           [0008]    More particularly, it is an object of the present invention to provide a transfer device/catheter assembly in which the treatment elements cannot be inadvertently released from the transfer device.  
         SUMMARY OF THE INVENTION  
         [0009]    These objects, as well as others which will become apparent upon reference to the following drawings and detailed description, are provided by a transfer device usable in a system for intraluminal treatment of a selected site in a body of a patient in which the transfer device comprises an integral pump for pressurizing and circulating fluid through a fluid path defined by the transfer device and associated catheter. A removable fluid cartridge is provided including a reservoir from which fluid is drawn by the pump and into which fluid is returned after being circulated through the fluid path. The pump may be a peristaltic pump and the fluid cartridge may include an elongated fluid pick-up having an inlet through which fluid is introduced into the transfer device. The fluid pick-up is sized in length so that the inlet is always submerged in the fluid regardless of the orientation of the transfer device. A removable treatment cartridge having a lumen forming part of the fluid path may also be provided, and a storage sleeve for the treatment cartridge may be of a radiation-blocking material, such as quartz. Further, the treatment cartridge may have a memory for storing and indicating selected information about the treating element.  
           [0010]    In another aspect of the invention, the transfer device may include a system for preventing operation of the transfer device unless each of the catheter, fluid cartridge and treating or source cartridge are attached to the transfer device. In a preferred embodiment, such a system may comprise an illumination source and an optical sensor located in the transfer device in proximity to where each of the catheter, fluid cartridge, and source cartridge is received by the transfer device. Each illumination source is located with respect to its optical sensor so that the optical sensor is able to receive light from its illumination source only if the catheter, fluid cartridge or source cartridge is not received by the transfer device. The optical sensor is blocked from receiving light from the illumination source when the catheter, fluid cartridge or source cartridge are received by the transfer device. A microprocessor that controls movement of the treating element from the transfer device to the catheter prevents operation of the transfer device upon receiving a signal from any of the optical sensors indicating that at least one of the catheter, fluid cartridge, and source cartridge is not attached to the transfer device.  
           [0011]    In a still further aspect of the invention, a catheter is provided for use in the intraluminal treatment system which has four lumens extending substantially along the length of the catheter, one lumen being sized to slidingly receive a treating element and being in fluid communication with two lumens at the distal end thereof for the return of fluid. The fourth lumen is open at the distal end to receive a guidewire. The catheter may have a distal end with a cross-sectional area smaller than the proximal end of the catheter, the cross-sectional shape being non-circular so as to permit perfusion.  
           [0012]    In a further aspect of the invention, the transfer device includes a gate movable between first and second positions for selectively permitting or preventing the treating element from moving from the treating element cartridge to the catheter, with an actuator controlling the gate that also permits release of the catheter and the treating element cartridge from the transfer device only when the gate is in position to prevent the treating element from moving from the treating element cartridge to the catheter.  
           [0013]    In a further aspect of the invention, the transfer device includes a system for detecting the presence or absence of the treating element in the storage sleeve including a light source disposed on one side of the storage sleeve and a linear array of photosensors disposed on a second side of the storage sleeve. A microprocessor is provided for comparing the amount of light measured by the photosensors to a reference amount corresponding to the amount of light measured by the photosensors when the treating element is not within the lumen of the storage sleeve. 
       
    
    
     DRAWINGS  
       [0014]    [0014]FIG. 1 is a perspective view of an automated transfer device in accordance with the present invention.  
         [0015]    [0015]FIG. 2 is a side view of the automated transfer device of FIG. 1.  
         [0016]    [0016]FIG. 3 is a bottom view of the automated transfer device of FIG. 1.  
         [0017]    [0017]FIG. 4 is an exploded view of the automated transfer device of FIG. 1 including a fluid cartridge, a source cartridge, and a gate actuator assembly.  
         [0018]    [0018]FIG. 4A is an exploded view of the fluid cartridge of FIG. 4.  
         [0019]    [0019]FIG. 4B is an exploded view of the source cartridge of FIG. 4.  
         [0020]    [0020]FIG. 4C is an enlarged view of the gate actuator assembly of FIG. 4.  
         [0021]    [0021]FIG. 5 is a perspective view of the automated transfer device of FIG. 1 with the upper half of the housing removed, with selected internal components shown in exploded view.  
         [0022]    [0022]FIGS. 6A and 6B are perspective views of selected internal components of the automated transfer device of FIG. 4.  
         [0023]    [0023]FIG. 7 is a schematic diagram showing the fluid flow path within the automated transfer device of FIG. 4.  
         [0024]    [0024]FIG. 8 is a perspective view of an alternative source cartridge to that shown in FIG. 4B.  
         [0025]    [0025]FIG. 9 is a further perspective view of selected internal components of the automated transfer device of FIG. 4.  
         [0026]    [0026]FIG. 10 is a schematic diagram of the system electronics for the automated transfer device of FIG. 1.  
         [0027]    FIGS.  11 - 22  are graphical representations of a series of display screens that are displayed by the automated transfer device of FIG. 1.  
         [0028]    [0028]FIG. 23A is a cross-sectional view of the proximal end of a delivery catheter in accordance with the present invention.  
         [0029]    [0029]FIG. 23B is a cross-sectional view of the distal end of the catheter of FIG. 23A.  
         [0030]    [0030]FIG. 24 is a cross-section view of a delivery catheter of the present invention.  
         [0031]    FIGS.  25  A-PP are graphical representations of an alternative series of display screens that are displayed by the automated transfer device of FIG. 1. 
     
    
     DETAILED DESCRIPTION  
       [0032]    The present invention comprises an automated catheter based radiation delivery system and its method of use for treatment of a desired area within the body of a patient. The system includes a delivery catheter, treatment elements, and a transfer device that electromechanically delivers the source train through the catheter to the selected location within a patient&#39;s body. The transfer device prompts the user to proceed appropriately through the procedure by displaying graphics and text via a LCD (Liquid Crystal Display) with a series of individual display prompts combining with operative input controls allows for an intuitive user interface.  
         [0033]    The assembled transfer device can be seen in FIGS.  1 - 3 . The exterior of the transfer device  10  is ergonomically designed to be easily held with either or both hands, making it equally adaptable for right and left-handed clinicians. As can be seen in FIGS. 1 and 2, curved handgrips  12  with finger rests  14  and thumb rests  16  are located on both the left and right sides of the transfer device  10 . Alternatively, the device  10  can rest in the palm of the user&#39;s hand or on a flat surface. The controls are easily reachable with the thumbs when both hands are supporting the device.  
         [0034]    An upper housing portion  18  and a lower housing portion  20  fit together to create the shell that holds the internal components openings in the upper housing portion  18  allow a user to access a display  22 , control buttons  24 ,  26 ,  28 ,  30 , indicator LEDs (Light-emitting Diodes)  32 ,  34 ,  36 , and a latch member  38 . The upper portion  18  also includes a window  40  for viewing a sleeve  42 , which houses a source train  43  (comprising treatment elements and marker seeds), and a pin gate  44 . The sleeve  42  is preferably made of a radiation-blocking material, such as quartz, synthetic fused silica, polycarbonate plastic, etc.  
         [0035]    The lower housing portion  20  has a central opening for mounting the power supply for the device, most likely a replaceable or rechargeable battery pack  48 . A hard cover  46 , as shown in FIG. 2, is securely positioned over the power supply, completely closing the opening. The battery pack  48  may have an integrated plastic housing with external contacts that connect electrically with those on the transfer device  10  to ensure its ease of replacement or recharging. This battery pack would reside along the exterior of the transfer device  10  and be instantly accessible by the user.  
         [0036]    The upper and lower housing portions  18 ,  20  together also create an opening for the insertion of a fluid cartridge assembly  50 . The fluid cartridge  50  contains saline, sterile or distilled water, or some other fluid source for the hydraulic delivery of the source train  43 .  
         [0037]    The fluid cartridge assembly  50  includes a cylindrical fluid reservoir  52 , an end cap  54  that channels the fluid in and out of the fluid reservoir  52 , and a handle  56  for insertion and removal of the fluid reservoir  52  with respect to the transfer device  10 , best seen in FIGS. 4A and 5. The end cap  54  acts as a fluid manifold and comprises a fluid pick-up in the form of an elongated appendage  58  having a fluid channel or inlet through which fluid is introduced into the transfer device. The end cap  54  may be an integral part of the transfer device and adapted to mate with the fluid reservoir  52  upon its insertion into the transfer device. The distal center portion of the fluid reservoir  52  has a recessed opening  60  for the receipt of the fluid pick-up  58 . Adjacent to the opening  60  is a fluid return hole  62  that allows fluid to return to the reservoir  52  after it has circulated through the transfer device and its associated catheter.  
         [0038]    The dimensions of the reservoir  52  and the volume of the fluid are such that the fluid level never falls below the recess  60  when handling the transfer device  10 . The angle at which one holds the transfer device  10  may shift some fluid from one side of the recess  60  to the other, but the free end of the appendage  58  will always be submerged in fluid. Thus, only fluid can enter the fluid channels of the appendage  58 . This is important because of the need to reduce the likelihood of air bubbles getting into the fluid path.  
         [0039]    The fluid reservoir  52  is removable for cleaning and for replacing the used fluid with fresh fluid. It simply unscrews from the fixed end cap  54 . Alternatively, the fluid cartridge  50  may be disposable. At the end of each treatment, the used fluid cartridge  50  can be discarded and replaced with a new pre-filled cartridge.  
         [0040]    As shown in the fluid flow diagram of FIG. 7, the fluid flow path begins within the fluid reservoir  52  and continues throughout the delivery system. The fluid cartridge exit port  64  (FIG. 4A) is in fluid communication with a peristaltic pump  66 , which draws the fluid in and forces it through fluid channels to effectively deliver, maintain, and retrieve the treatment elements. The peristaltic pump  66  can be programmed to operate in a single direction for both sending and retrieving the treatment elements, or can be programmed to alternate directions between the sending and retrieving modes.  
         [0041]    When pumping fluid in a single direction, the system relies on a fluid control valve, preferably a solenoid valve  68 , working with the microprocessor to properly direct the fluid flow. Alternatively, a manual valve could be used to control the fluid flow. The fluid control valve  68  is in fluid communication with all fluid channels in both the source cartridge  70  and the attached delivery catheter  140  or  142 . In the send mode, the fluid control valve  68  automatically directs the fluid flow through the source cartridge  70 , into the catheter through the source delivery lumen, and out of the catheter through the fluid return channel. In the return mode, the fluid control valve  68  automatically reverses the direction of flow.  
         [0042]    In use, greater force is required to send and retrieve the treatment elements to and from the catheter than to maintain them at a desired location in the catheter for treatment. Therefore, to conserve energy, the pump  66  operates at a decreased speed when maintaining the position of the treatment elements. When the treatment is complete, the pump  66  resumes full speed to force the treatment elements back into the source cartridge  70  within the transfer device  10 . The pump  66  is idle when no treatment elements are being sent, maintained, or retrieved.  
         [0043]    In the event the pump  66  becomes inoperable at a time when the treatment elements are not housed within the source cartridge  70 , the user may manually override the automatic fluid management system to retrieve the elements. For example, a luer connector (not shown) accessible to the user may be in fluid communication with the fluid flow path, and a fluid filled syringe can be attached to the connector and used as a source of pressurized fluid to force the return of all treatment elements to the source cartridge  70 .  
         [0044]    In keeping with a further aspect of the invention, the transfer device  10  comprises an interchangeable source cartridge assembly  70  (best seen in FIG. 4). In order to be capable of delivering variable source train lengths, the source cartridge assembly  70  houses the quartz sleeve  42  which in turn houses the source train  43  and the pin gate  44 . Interchangeable cartridges  70  of variable source train lengths allow the user to select a cartridge having a source train  43  of the appropriate length to treat the patient. Each cartridge  70  has the capability to store the maximum length source train  43 , which may be up to 60 mm for coronary vessels and up to 150 mm for peripheral vessels. A source train  43  that is shorter than the maximum length is accompanied by a retainer (not shown) that maintains the source train  43  immediately adjacent to the pin gate  44  in the distal end of the quartz lumen  72 . When inserted into the transfer device, the source cartridge  70  completes the fluid path by fluidly connecting the solenoid valve  68  to channels within the transfer device  10  and the delivery catheter.  
         [0045]    With reference to FIG. 4B, the top central portion of the source cartridge has an elongated opening  74  that permits the user to view the transparent quartz sleeve  42 . A clear window piece  40  fits within the opening  74  for visual detection of the treatment elements and the pin gate  44 , which are housed by the quartz sleeve  42 . For magnification of the treatment elements and marker seeds, a magnifying lens could replace the entire window  40 . The distal end of the window  40  or magnifying lens may be coupled to a circular lens  76  that further magnifies at least the pin gate  44  and the distal marker seed area of the source train  43 .  
         [0046]    The source cartridge  70  houses the source train  43  in a central lumen  72  that runs along the entire length of the quartz sleeve  42 . A pin gate  44 , similar to that disclosed within FIGS. 39A and 39B of U.S. application Ser. No. 08/936,058, incorporated by reference above, lies within a channel that is perpendicular to the central lumen  72  and that connects the central lumen  72  to the exterior of the quartz sleeve  42 . The pin gate  44  is maneuvered between a closed position, where it intersects the quartz lumen  72  to prevent the source train  43  from exiting the quartz  42 , and an open position, where it retracts to allow the delivery of the source train  43  into the catheter. Within an opening in the source cartridge  70  and external to the quartz sleeve  42  rest the remaining components of the pin gate mechanism  44 : a pin  80 , a seal (not shown), a cylindrical bar  82 , and a compression spring (also not shown). One end of the spring is affixed to an exposed portion along the source cartridge  70 . With reference to FIGS. 6A and 6B, the cylindrical bar  82  has two centrally located circular recessed areas  84 , each on opposing sides. The free end of the spring fits within one recess  84  and the head of the pin gate  44  fits within the other recess  84 . The seal resides within the quartz channel and closes around the pin gate  44  to create a fluid tight seal as the pin gate  44  is maneuvered back and forth between closed and open positions.  
         [0047]    The source cartridge assembly  70  also includes a large knob-like handle  86  for facilitating easy insertion into and removal from the transfer device  10  (best seen in FIGS.  4 - 6 B). The handle  86  may include an indication of the source train length and/or may be color coded to differentiate it from other cartridges  70  that contain different length source trains. The interior of the handle  86  is hollow and houses a spring loaded button  88  with a pin (not shown). The cylindrical portion  90  of the button  88  extends through an opening  92  in the top of the handle  86  and the pin extends through an opening  94  in the side of the handle  86 . As the cartridge  70  is inserted into the transfer device  10 , the pin (and thus, the button) is forced downward by a negatively sloped overhang  96  on the upper housing portion  18  of the transfer device. Because the pin is an integral with the button  88 , the button  88  is forced downward compressing the spring. Once the cartridge  70  is fully engaged, the pin is no longer hindered by the overhang  96 , and the bias of the spring forces the pin upward into a notch (not shown). The spring decompresses and the button  88  fully extends. The cartridge  70  can only be removed from the transfer device  10  by depressing the button  88 , thereby lowering the pin below the notch. Otherwise, movement of the pin is restricted by the wall of the notch.  
         [0048]    The source cartridge may also include non-volatile memory that stores specific information regarding the source train  43 , such as the its length, its radiation activity, and the number of times it has been used for radiation treatment. The stored data is a compilation of alpha-numeric characters. With reference to FIG. 8, this “smart” cartridge  71  communicates with the transfer device  10  through electronic connectors  98 , one within each of the cartridge  71  and the transfer device  10 . When the source cartridge  71  is inserted into the transfer device  10 , the two electrical connectors come into contact, and the transfer device  10  reads the data stored in the memory and displays it to the user. Based on the information displayed, the user can determine if the desired cartridge  71  has been inserted. The transfer device  10  may also perform a check on the data to make sure it falls within the designated limits. If the data falls outside the limits, the transfer device  10  will indicate an error and will not allow treatment to begin.  
         [0049]    The delivery catheter is connected to the transfer device  10  through a proprietary connector  99  located along the catheter&#39;s proximal end. The opening in the transfer device  10  for the insertion of the connector  99  is lined with a fluid seal  100  that includes a fluid port  102  in fluid communication with the solenoid valve  68 . With reference to FIGS. 5 and 6A, as the connector  99  is inserted into the transfer device  10 , it passes through the fluid seal  100 , through the connector latch  38 , and finally mates with the solid cone member  104  (best seen in FIG. 9) on the distal end of the source cartridge  70 . The spring loaded latch  38  must be pressed down for the receipt of the connector  99 . Otherwise, the correct sized opening is not aligned with the connector  99 . After the connector  99  is inserted, the latch  38  can be released. It springs upward, engaging the undercut portion of the connector  99 . The latch  38  must be held down to release the connector  99  from the transfer device  10 .  
         [0050]    Prior to disconnecting the catheter or source cartridge  70 , the user must be assured that all treating elements are positioned within the quartz housing  42  and behind the closed pin gate  44 . Accordingly, in addition to the visual detection of the source train  43 , an electronic detection system is included within the transfer device  10 . Turning to FIG. 9, the electronic detection system utilizes the combination of a light source  106  (which may be either visible, such as a laser, or infrared light) and a linear CCD (Charged Coupled Device) array  108 . The light source  106  and the linear CCD array  108  are positioned on opposite sides of the cartridge  70 . The light from the light source  106  travels through a jacketed fiber optic bundle  110  to produce a linear beam or plane of light. The linear beam of light shines through a longitudinal slot  112  along the side of the cartridge  70  and illuminates the pin gate  44  and a portion of the quartz lumen  72 . The source cartridge  70  has slots  112  adjacent to both the illuminator  106  and the CCD array  108  to allow the light to pass therethrough (See FIGS. 4, 6B,  8 ).  
         [0051]    The linear CCD array  108  comprises a row of photosensors that measure light directed toward them. If the entire source train  43  is within the housing  18 ,  20 , then the light cast upon the photosensors will be less than when one or more elements is missing. Thus, the electronic system can determine whether or not all treating elements and marker seeds are present by reading the output voltage, which is directly proportional to the amount of light detected by the CCD array  108 .  
         [0052]    Because of the capability to use variable source train lengths, the optical sensing system detects the presence of only a distal portion of any source train  43 . Preferably, at least the distal most five elements of any train  43  will be detected in a given location for a predetermined amount of time. If the last five elements (distal marker seed and four treating elements) of any given source train  43  are present, the user can reasonably assume that the remaining source train elements proximal to the range detected are also be present.  
         [0053]    Three indicator LED&#39;s  32 ,  34 ,  36  (FIG. 1) are visible to user along the face of the transfer device  10 . When the electronic detection system senses that the source train  43  is present and the gate  44  is closed, an assigned LED  32  (preferably a green LED) lights up to signal this to the user. When the electronic detection system senses that the source train  43  is missing and/or the gate  44  is open, the green LED  32  turns off and an assigned LED  34  (preferably an amber one) lights up to warn the user. Either the green or amber LED will be lit; it will never be both. The third LED  36  (preferably red), when lit, indicates a low battery. The low battery LED  36  can be lit up simultaneously with either of the other two indicator LEDs  32 ,  34 .  
         [0054]    In addition to the electronic detection system for sensing the presence of the source train, other sensors may be included within the transfer device  10  to detect the presence of the fluid cartridge  50 , source cartridge  70 , and proprietary connector  99 . Such sensors may be any of a number of well-known types, such as mechanical, electromechanical (e.g., a leaf spring with a microprocessor measuring its movement or detecting its position), electrical (e.g., a trip switch or limit switch), magnetic (e.g., a reed switch with a permanent magnet), electromagnetic (e.g., Hall effect sensors), or optical sensors. Other types of sensors include displacement and position sensors, proximity sensors, occupancy motion detectors, pressure sensors, and force or strain sensors.  
         [0055]    In the illustrated embodiment, for each of the three connections, an optical sensor can be coupled with an illumination source, such as an infrared LED. The illumination sources would be positioned such that each of the fluid cartridge  50 , source cartridge  70 , and proprietary connector  99  break the light beam of its illumination source when fully inserted into the transfer device  10 . The sensor detects the change in the amount of projected light and communicates this with the electronic controls of the system. If one or more of the fluid cartridge  50 , source cartridge  70 , and delivery catheter are not properly inserted within the transfer device  10 , the graphic user interface displays the missing connection(s) and will not allow the user to proceed further until corrected.  
         [0056]    The gate actuator assembly  114 , best seen in FIGS. 4C and 6, controls the opening and closing of the pin gate  44 . It comprises a drive motor  116 , a worm gear  118 , an attachment or mounting member  120  secured to the worm gear  118  that moves linearly upon rotation of the worm gear, and a U-shaped plate  122 . The mounting member  120  has a central portion with a diagonal slot  124  therethrough, a neck  126  extending distally from the central portion with a raised post  128  at its distal-most end, and a long rod  130  extending proximally from the central portion. The U-shaped plate  122  (see FIG. 5) is movably coupled to the slot  124 .  
         [0057]    In operation, when the user activates the send mode, the motor  116  rotates the worm gear and the attachment  120  moves linearly towards the proximal end of the source cartridge  70 . Thus, the mounting member  120  forces the U-shaped plate  122  in a forward position, perpendicular to that of the worm gear  118 . The U-shaped plate  122  straddles the pin gate  44  as it intersects the top of the cylindrical bar  82 , forcing the pin  80  down into an open gate position.  
         [0058]    The gate actuator assembly  114  simultaneously provides additional protection against removing the catheter and/or the source cartridge  70  while the gate  44  is open. The rod  130  moves under the pin extending from the side of the source cartridge handle  86  so that the spring loaded button  88  cannot be pressed downward to disengage the cartridge  70  from the transfer device  10 . The raised portion  128  at the distal end of the mounting member  120  moves directly under the shoulder  39  of the latch  38  so that the latch  38  cannot be pressed downward to disengage the proprietary connector  99 .  
         [0059]    A block diagram of the system electronics is shown in FIG. 10. The electronics are built onto two printed circuit boards, an interface board  134  and a controller board  136 . In addition to performing the source sensing algorithms, the interface board  134  drives the pump motor  66 , the gate assembly motor  116 , the solenoid  68 , and the indicator LEDs  32 ,  34 ,  36 . The controller board  136  displays a series of screens on a LCD  22  (see FIGS. 1 and 5) and commands the interface board  134  based on user inputs  138 , which are entered through user interface buttons  24 ,  26 ,  28 , and  30 . The display screens can be designed many different ways depending on how much information the user desires to receive and the level of input to be given by the user.  
         [0060]    FIGS.  11 - 22  show an example of a series of display screens that are useful in assisting the user to perform a radiation treatment procedure. In this example and as shown in FIGS. 1 and 5, the transfer device  10  has three specific function buttons  26 ,  28 ,  30  and at least two generic function buttons  24 . The specific function buttons are the “POWER” button  26 , the “ABORT” button  28 , and the “HOME” button  30 . However, these buttons  26 ,  28 , and  30  are provided to bypass software interrupters and could be programmed for different functions as needed. The generic function buttons  24  correspond to display prompts and are backlit when associated with an input of an individual screen. If an individual display screen does not have an input associated with a generic button  24 , then that button will be disabled. An LED is placed underneath each button  24 ,  26 ,  28 , and  30 ; however, only the active buttons for each individual screen will be backlit.  
         [0061]    Pressing the “POWER” button  26  turns on the electronics. As the system powers up, the electroluminescent or LED backlighting illuminates, and all LEDs flash on and off for a period of time to indicate that the system is operative. The green LED  32  remains lighted if the source sensing system determines that the pin gate  44  is closed and the treatment elements are stored within the quartz housing  42 . Otherwise, the amber LED  34  is lighted to indicate missing treatment elements or an open pin gate  44 .  
         [0062]    The first display screen (FIG. 11) identifies the manufacturer of the device for a short amount of time, and then the system automatically flashes the second screen, which prompts the user to choose between two or more source trains. Upon the user choosing one, the system then moves on to a new screen (FIG. 12 or FIG. 13 depending on choice of 50 mm or 20 mm cartridge) that asks for conformation of the user&#39;s choice.  
         [0063]    The user can stop the procedure at any time by pressing the “ABORT” button  28  on the face of the transfer device  10 . To continue, the “yes” button  24  is pressed and the priming screen (FIG. 14) prompts the user to decide if the device  10  shall be primed with fluid prior to the delivery of the treatment elements. If “no” is chosen, the system immediately goes to the radiation dosage screen (FIG. 15), which prompts the user to choose a dose of either 14 Gy or 18 Gy. Otherwise, the pump  66  and the solenoid  68  become active and pump fluid through the device&#39;s fluid channels while maintaining the treatment elements within the source cartridge  70 .  
         [0064]    The next screen (FIG. 16) displays the treatment time based on the prescribed dosage and information stored in the smart cartridge and prompts the user to begin the treatment. When the send mode is initiated, the pump  66 , solenoid  68 , and gate actuator assembly  114  work together to send the treatment elements to the distal end of the catheter. The amber LED  34  lights up in place of the green LED  32  when the pin gate  44  opens and the source train  43  exits the quartz sleeve  42 . At this point, a new screen (FIG. 17) appears stating that it is waiting for the treatment elements to get to the end of the catheter.  
         [0065]    Once the treatment elements are in place, the speed of the pump is reduced by 50% for maintaining the treatment elements at the desired location and the following display screen (FIG. 18) begins to countdown the treatment time. As the treatment time approaches zero, the pump  66  resumes full speed for returning the treatment elements. As soon as the treatment time is over, the solenoid valve  68  reverses the direction of the fluid flow, and the treatment elements are forced back into the quartz sleeve  42 .  
         [0066]    Once the treatment elements have returned, the optical sensing system detects the presence of the source train  43 , the gate  44  moves into the closed position, and the pump  66  and solenoid  68  are turned off. The green LED  32  is illuminated in place of the amber LED  34  to indicate the presence of the treatment elements to the user. The next screen (FIG. 20) confirms that the gate  44  is closed. The next to the last screen (FIG. 21) displays the final treatment time (the initial set time minus the return time), and the last screen (FIG. 22) prompts the user to turn off the system power.  
         [0067]    If for any reason the user wanted to abort the treatment once in progress, it can be done by pressing the “ABORT” button  28 . This will freeze the timer and activate the screen shown in FIG. 19. The user is given the option to immediately return the treatment elements to the transfer device  10  or to continue sending the treatment elements for treatment. If the returning the source train  43  to the transfer device  10  is the choice, screens depicted in FIGS.  20 - 22  follow as described previously. If the choice is to resume sending the source train  43  for treatment, then screens depicted in FIGS. 18, 19,  20 ,  21 , and  22  follow as described previously.  
         [0068]    Also, at any time following the release of the source train  43  into the delivery catheter, the user has the option to automatically return the source train  43  to the transfer device  10  by depressing the “HOME” button  30 . An additional series of display screens are shown collectively in FIG. 25 A-PP, which consists of forty-two individual screens laid out sequentially.  
         [0069]    The transfer device  10  can be connected to any of the catheters that are disclosed in the patent and applications previously incorporated herein by reference. Additionally, catheters  140 ,  142 , having the cross-sections illustrated in FIGS.  23 - 24 , may be used to deliver the treatment elements to a selected site within a patient. Catheters  140  and  142  may be constructed of any material, or a combination of materials, such as nylon, PEBAX, polyethylene, and polyurethane. A proximal segment  144  (FIG. 23A) and a distal segment  146  (FIG. 23B), each of different durometer and stiffness characteristics, are co-extruded and fused together, or variably extruded, to create an elongated catheter  140  having four lumens: a source train delivery lumen  148 , two fluid return lumens  150 , and a guidewire lumen  152 . All four lumens extend along the entire length of the catheter  140 , and the source train lumen  148  communicates at its distal end with both fluid return lumens  150 .  
         [0070]    As seen in FIG. 23B, the distal segment  146  of the catheter  140  has a non-circular cross-sectional shape, with a reduced profile along its length to provide pathways  154  for the perfusion of blood. As a result of the reduced profile, the distal segment  146  of the catheter  140  has increased softness and flexibility, which allows for easier and farther advancement of the distal segment, especially into the more distal and tortuous regions within the human body. Additionally, the softer distal segment  146  improves catheter trackability over a guidewire and creates an atraumatic tip for lessening intraluminal damage as the catheter travels through the patient to the lesion site. The proximal segment  144  of the catheter  140  is circular, unlike the distal segment  146 , and utilizes its increased mass and stiffness to advance the catheter  140  through the tortuous vasculature.  
         [0071]    The catheter  142  (FIG. 24) is of a single extrusion and has the same cross-sectional profile along its entire length. This catheter  142  also has a source train lumen  156 , two fluid return lumens  158 , and a guidewire lumen  160 . The guidewire lumen  160  may have a protective liner  162  of, e.g., polyimide, and may be coated with Teflon (polytetraflourethylene) or other lubricious material for easier manipulation of the catheter  142  over a guidewire.  
         [0072]    The treatment elements and marker seeds of source train  43  (see FIG. 4) may also be any of those described in the patent and applications previously incorporated herein by reference. A source train  43  consists of a series of treatment elements and two marker seeds, one at each end of the source train  43 . Preferably, the treatment elements are radioactive cylinders. The marker seeds are used to properly position the treatment elements at the treatment site and are preferably gold or gold plated, since gold is visible under fluoroscopy, which is used to monitor the radiation therapy.  
         [0073]    Accordingly, an intraluminal radiation treatment system has been disclosed that meets all the objects of the invention. While the system has been described in terms of a preferred embodiment, there is no intent to limit the invention to the same. Instead, the invention is defined by the following claims.