Abstract:
A template for surgically implanting needles into a patient&#39;s body. A support backing of the template specifically angled and curved to conform to a body structure to provide stability in the relative positions between the body and the template. The template further having a locking mechanism to hold needles in place after they have been inserted into the body structure, the locking mechanism utilizing a channel to guide a floating plate in vertical motion with respect to a contiguous stationary plate. When force is applied to the floating plate, the relative motion of the plates puts a locking force on the needles which run through holes in the two contiguous plates. A hollow protective covering to be mounted over the front face of the template to protect the ends of the needles that have been inserted through the template and into the patient.

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to a template for the surgical implantation of needles into a patient&#39;s body, and more specifically to a template for implantation of needles for prostate brachytherapy. 
     BACKGROUND OF THE INVENTION 
     Various forms of cancer are treated by exposing cancerous tissues to controlled doses of radiation. One technique for delivering a dose of radiation to cancerous tissue is brachytherapy. Brachytherapy is a procedure that involves the implantation of radioactive sources in or near cancerous tissue in order to apply a desired dose of radiation. By implanting a radioactive source in or near targeted cancerous tissue, the desired radiation dose can be delivered, while limiting radiation exposure to other tissues. Brachytherapy which utilizes needles containing one or more radioactive sources to deliver the desired radiation dose into a patient is known to be an effective technique for treating prostate cancer. 
     In administering brachytherapy, a doctor will formulate a three dimensional dosimetry pattern for the placement of radioactive sources within a cancerous organ. In the seed implantation form of brachytherapy, radioactive “seeds” are discharged within the targeted cancerous organ via one or more hollow needles in accordance with the predetermined dosimetry pattern and these seeds are left inside the patient to deliver the desired radiation dosage. The implanted seeds are left within the patient to continue to deliver radiation even after the patient leaves the hospital. The level of radioactivity of the implanted seeds then gradually deteriorates until it becomes insignificant. 
     Another brachytherapy technique is to insert into and remove from a patient more intense radioactive sources in a timed pattern via hollow needles inserted into a target region. This technique, known as high dose rate brachytherapy (“HDR”) delivers a desired dosage in a short amount of time, but avoids permanently implanting radioactive seeds. During an HDR treatment a timed pattern of intense radioactive sources are inserted and retracted through the needles over several minutes. This technique requires that the brachytherapy needles remain in the patient for many hours while a series of HDR treatments are administered. 
     For brachytherapy to have its desired effect it is important that a doctor be capable of precisely placing the brachytherapy needles into the patient. Needles are placed using a template which includes a grid of needle holes. Each needle hole on the grid may be uniquely identified by its own vertical and horizontal coordinates. It is intended that such a needle template be maintained at a constant position with respect to the patient&#39;s body surface and the cancerous organ. Thereby the preplanned dosimetry pattern may be implemented by inserting the needles through their designated coordinates on the template and into the patient. 
     In conjunction with a needle template, an ultrasound device is used to monitor the placement of the needles. In the case of prostate brachytherapy treatment, the ultrasound device is inserted into the rectum of the patient. During treatment, the needle template may be directly mounted on the ultrasound device to maintain a constant relative position between them. The needle template can also be sutured in place on the patient&#39;s body. 
     Once the needles have been inserted into the patient, it is desirable to provide a locking mechanism in the template to hold the needles in place so that the needle insertion depth will not change unintentionally. A conventional design for a locking mechanism is to make the template from a “sandwich” of three plates through which the needle holes extend. In this design, the outer and inner plates are fixedly positioned with respect to one an other and the middle plate moves slidably in a vertical direction between the two outer plates. Once the needles have been inserted through the template as desired, the needles are locked by turning a screw to apply vertical force to the middle plate thereby causing the middle plate to apply a vertical force to the needles in the template, preventing their unintentional movement. 
     For prostate brachytherapy, needles are inserted through the perineum of a patient to deliver a radioactive source to a cancerous prostate gland. To perform this procedure the patient is placed in thelithotomy position. The needle template is supported in a vertical upright position so that the needles may be inserted into the patient on a flat horizontal plane. 
     In attempting to maintain a constant position of the template relative to the patient during prostate brachytherapy, the template is sutured to the patient&#39;s skin in the perineum region. To support the template in place relative to the perineum, and to allow the sutures to be made, the template is rested in close contact with the surface of the perineum. 
     However, it is difficult to secure the known templates in place as these are generally square or rectangular and flat on the front and back surfaces. Flat templates are inconsistent with the shapes of patients&#39; perineums. 
     In an attempt to address this problem, the gaps between the skin of the patient and the template have been stuffed with material such as gauze. However, such gauze stuffing is often irregular and can result in a cleanliness problem as the stuffing absorbs blood. Also, gauze stuffing may interfere with making a good suture of the template to the patient. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a brachytherapy needle template comprising an inclined and/or curved support backing conforming to a shape of a part of the patient&#39;s body. This support backing includes suturing eyelets which, when the device is in an operative position, are located adjacent to the patient&#39;s skin. This inclined and/or curved support backing allows the needle grid portion of the template to remain vertical when placed against the patient so that the needles may be inserted horizontally. 
     The present invention is further directed to a needle lock mechanism for holding the needles in place once they have been inserted into a patient. The needle lock mechanism comprises an arrangement of two plates, one of which moves slidably with respect to the other wherein the movable plate slides within a vertical channel formed, for example, by placing horizontal pins in a portion of the support backing. After the brachytherapy needles have been placed through the plates, a vertical force is placed on the movable plate and the force on the movable plate locks the needles in place. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1A shows a front view of a preferred embodiment of the needle template according to the present invention for use in prostate brachytherapy; 
     FIG. 1B shows a side view of a preferred embodiment of the needle template according to the present invention for use in prostate brachytherapy, including a partial cut away view of the plates and needle holes in the needle template; 
     FIG. 1C shows a top view of a preferred embodiment of the needle template according to the present invention for use in prostate brachytherapy; 
     FIG. 2A shows a side view of the needle template according to the present invention illustrating the functionality of the locking mechanism; 
     FIG. 2B shows a front view of the needle template according to the present invention illustrating the functionality of the locking mechanism; 
     FIG. 3A shows a front view of a preferred embodiment of the protective covering attached to the face of the needle template according to the present invention; 
     FIG. 3B shows a side view of a preferred embodiment of the protective covering attached to the face of the needle template according to the present invention; 
     FIG. 3C shows a top view of a preferred embodiment of the attaching portion of the protective covering according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIGS. 1A-1C show a needle template  10  according to a preferred embodiment of the invention. FIG. 1A shows a substantially rectangular front plate  11  of the needle template  10 . Needle holes  12 , formed in a grid pattern, extend through the front plate  11  and a corresponding grid of needle holes  12 ′ extends through a movable plate  13  received behind the front plate  11 . Those skilled in the art will understand that the shape of the front plate  11  is unimportant so long as the desired number and location of needle holes  12  can be accommodated therein. The needle holes  12  and  12 ′ are sized to accept brachytherapy needles (not shown), which typically range in size, for example, from 14 to 20 gauge. 
     when the grid patterns on the two plates  11  and  13  are aligned, brachytherapy needles can be inserted through the needle holes  12  in the front plate  11  and then through the holes  12 ′ in the movable plate  13 . As an end of a needle passes rearwardly from the movable plate  13 , the end of the needle passes through gap  17 , as seen in FIG. 1C, and passes from this gap into the patient. As will be explained in more detail below with respect to FIGS. 2A and 2B, by applying a vertical force to the movable plate  13 , via lock knob  20 , the movable plate  13  will be slightly moved upward with respect to the front plate  11 , thereby applying a locking force to any needles inserted therethrough. 
     As shown in FIGS. 1B and 1C, front plate  11  is fixedly attached to support backing  14  which extends rearward from front plate  11 . Support backing  14  extends rearwardly from plates  11  and  13 , providing a frame for supporting and stabilizing plates  11  and  13  relative to a body part to be operated on. In a preferred embodiment of the invention, the front plate  11  and the support backing  14  may be integrally formed from a single piece of material. Support backing  14  extends rearwardly from the left and right edges of front plate  11  to form left and right rearward vertical supports  15  and  16 . The rearward surfaces of the support backing  14 , including rearward edges of the vertical supports  15  and  16 , are shaped to conform to a body surface into which the needles are to be inserted. 
     As shown in FIG. 1B, for example, the rearward surfaces of support backing  14  are angled to account for a vertical and/or horizontal slope of the body part. For example, if the top portion of the body part is farther from plates  11  and  13  than the bottom portion, the top portion of the support backing  14  will preferably be formed extending rearward at an angle, θ, offset from the vertical in relation to a bottom portion of the support backing  14 . Similarly if, when in a preferred position, a left portion of the body part is farther from the front plate  11  than a right portion, the left side of the support backing  14  would be extend rearward at an angle appropriate to offset the difference. 
     As shown in FIG. 1B, the rearward surfaces of support backing  14  are also curved, for example, as defined by a radius R, to correspond to a curvature of the body part against which it is to be seated. Of course, those skilled in the art will understand that, where a body part curves with respect to a vertical axis, the rear surfaces of support backing  14  may preferably be curved, for example, along a circle of radius R, to approximate this curve. 
     For a template embodiment used for prostate brachytherapy, as shown in FIGS. 1A-C, the support backing  14  includes both an angle and a curve so that the template  10  can rest stabily and comfortably against the perineum. To rest stabily against the perineum, an angle θ between the upper portion of support backing  14  and the vertical may, for example, be approximately 20 degrees. Angles θ, in the range of 5 to 45 degrees are also suitable for use in the prostate brachytherapy embodiment. A support backing  14  having a curvature with a radius of 4.55 inches is preferred. However, radii in the range of 3 to 6 inches are also suitable. 
     As shown in FIG. 1C, an open gap  17  extends between the left rearward vertical support  15  and the right rearward vertical support  16 . This open gap  17  corresponds to a region in which the needles exit the movable plate  13  and then proceed rearwardly to enter the body. Gap  17  allows medical personnel to observe the entry of the needle into the body, and to make any necessary adjustments. 
     Also shown in FIG. 1C is a horizontal support component  18  of the backing support  14  which extends from the upper portion of left rearward vertical support  15  to the upper portion of right rearward vertical support  16 . Horizontal support  18  adds additional surface area with which to maintain stability against the body part and allows viewing and access into the gap  17 . The rear surface of horizontal support  18  may also preferably be angled and/or curved to conform to angles and curves of the portion of the body with which it is to be in contact. 
     For different applications of the present invention, other combinations of vertical supports  15 ,  16  and horizontal supports  18  may be employed to achieve the desired structure for a support backing  14 . 
     As shown in FIGS. 1A-C, suture eyelets  19  are formed at a rearward corners of support backing  14 . As with the rest of support backing  14 , the rearward surfaces of eyelets  19  may also be angled and curved to correspond to a contour of the body. This angling and curvature of the suture eyelets  19 , allows the suture eyelets  19  to be positioned in close proximity to the surface of the body part, thereby allowing the needle template  10  to be securely sutured to the patient. 
     Front plate  11 , movable plate  13 , and support backing  14  may preferably be manufactured from a strong but light material, such as, for example, aluminum or, more preferably, clear polycarbonate. Clear polycarbonate is strong and allows light to pass therethrough allowing medical personnel to more clearly see the needle insertion in the body. The clear polycarbonate may also be easily milled and drilled to form the structures discussed above. Also in a preferred embodiment, removing polycarbonate to hollow out structures such as the left and right rearward vertical supports  15  and  16  will reduce the weight of the device, reducing strain on the sutures attaching the needle template  10  to the patient. 
     FIGS. 2A and 2B show the locking mechanism of the invention which secures brachytherapy needles in place once they have been inserted into the patient. Specifically, the locking mechanism includes the fixed front plate  11 , the movable plate  13 , and needle holes  12  and  12 ′ formed in their respective matrices. Thus, when the plates  11  and  13  are aligned, each needle may be passed through a first hole  12  in plate  11  and then through a corresponding hole  12 ′ in plate  13 . To lock the needles in place, pressure is applied to move the movable plate  13  a slight distance upward with respect to the front plate  11 . This relative movement puts pressure on the needles extending through both the front plate  11  and the movable plate  13  and secures the needles in place. Those skilled in the art will understand that any directional displacement of the plate  13  to bring the grid of holes  12 ′ out of alignment with the holes  12 , will lock the needles in place. Thus, the plate  13  may be moved upward, downward, left, right, or in any combination of these directions to lock the needles in place. 
     In the preferred embodiment of the present invention, a lock knob  20  engage a tab  21  that extends from the top of the movable plate  13  above a top of the stationary front plate  11 . The lock knob  20  turns a screw  22  engaged in a threaded hole  23  which extends through the lock knob tab  21 . When the lock knob  20  is turned in a clockwise direction the screw  22  proceeds downward through the threaded hole  23  and comes into contact with the top of stationary front plate  11 . When the screw  22  is turned while it is in contact with the top of the front plate  11 , an upward force is applied to the floating plate  13  through the lock knob tab  21 . To prevent excessive shear stress from damaging the needles, the locking screw  22  is preferably only long enough to move the floating plate  13  a distance sufficient to lock the needles without damaging them. Thus, the screw  22  becomes fully engaged in hole  23  and will not turn any more in the clockwise direction when the maximum desired lift has been attained. Preferably, to avoid damaging the needles, the lift of the movable plate  13  may be limited to approximately 10% of the gauge diameter of needle holes  12 . 
     The movable plate  13  is held against the back of the stationary front plate  11  in a channel formed by channel pins  24  (also depicted in FIGS. 1B and 1C) extending horizontally from an inner surface of the support backing  14 . For example, the channel pins  24  extend inward from left and right rearward vertical supports  15  and  16 . The channel pins  24  may also be supported by any other structure which is fixedly attached to the stationary front plate  11 . For example, it is possible to position the floating plate  12  in front of the plate  11  by extending a support structure forward from the plate  11 , and positioning channel pins  24  there to form a channel for the floating plate  13 . 
     In addition to the channel pins  24 , two vertical tab pins  25  are positioned on top of the front plate  11  extending into corresponding vertical holes in the lock knob tab  21 . These tab pins  25  are slidably engaged in the vertical holes in the lock knob tab  21 , permitting vertical motion of the floating plate  13 . 
     In the preferred embodiment, the lock knob  20 , channel pins  24  and vertical tab pins  25  are made from stainless steel. 
     FIGS. 3A,  3 B and  3 C show a protective covering which further prevents the inadvertent movement of the needles once they have been inserted through the template  10  and into the patient. The protective covering  30  covers an outer face of the front plate  11  and extends outward to allow the ends of the brachytherapy needles to extend from the template  10 . For use in brachytherapy, the protective covering  30  preferably extends approximately six inches out from the face of the front plate  11 . A portion of the protective covering  30  adjacent to the template  10  may preferably be substantially cylindrical and may taper into a frustoconical shape as it extends outward therefrom. As shown in FIGS. 3A and 3B, an outward end of the frustoconical portion of the protective covering  30  may be open to a hollow interior thereof. This cylindrical and frustoconical design of the protective covering  30  provides protection for the needles without adding unnecessary edges or surfaces which may be inadvertently moved by a person or object. Other variations in the shape of the protective covering  30  will be apparent to those skilled in the art. 
     As shown in FIGS. 3A-3C, the protective covering  30  includes a mounting assembly  31  which includes slotted tabs  32  which extend rearwardly from the hollow conical portion of the protective covering  30 . To mount the protective covering  30  on the template  10 , the slotted tabs  32  are slid rearward to engage thumbscrews  33  which are mounted on the top of the front plate  11 . Once the thumbscrews  33  are fully engaged by the slotted tabs  32 , and the rear end of protective covering  30  is flush against the front plate  11 , the thumbscrews  33  are tightened down on the slotted tabs  32  to hold the protective covering  30  in place. 
     The protective covering  30 , including the mounting assembly  31 , may, for example, be made from clear acrylic. For ease of manufacturing, in the preferred embodiment the mounting assembly  31  may be formed separately and later glued to the rest of the protective covering  30  using a suitable adhesive. 
     The protective covering  30  prevents inadvertent movement of the needles by the patient or hospital personnel. The protective covering  30  also serves to keep the needles clean and unobstructed. Protection of the needles is especially important during in HDR brachytherapy procedure where a radioactive source must be able to slide in and out of the needles in an unobstructed manner and where the needles must remain within the patient for an extended time. 
     There are many other variations of the above described embodiments which will be apparent to those skilled in the art. It is understood that these modifications are within the teaching of the present invention which is to be limited only by the claims appended hereto. In addition, although the operation of the preferred embodiments have been described in regard to prostate brachytherapy, those skilled in the art will understand that this invention may also be used to perform other types of treatments which require the accurate placement of needles into a patient.