Abstract:
Methods and apparatus are provided for brachytherapy treatment of prostate disease. The apparatus comprises a housing, a plunger, a needle, and a lock. The plunger is rigidly affixed to the housing. The lock selectively restricts motion of the needle relative to the plunger. The needle comprises a screw thread that engages the housing or plunger. Rotation of the needle with respect to the housing/plunger causes distal advancement or proximal retraction of the needle with respect to the plunger, providing improved control over delivery of radioactive seeds to a diseased portion of a prostate.

Description:
FIELD OF THE INVENTION 
     This invention relates to improved apparatus and methods for the treatment of prostate cancer. More particularly, the present invention provides improved methods and apparatus for administering brachytherapy. 
     BACKGROUND OF THE INVENTION 
     Excluding nonmelanoma skin cancers, prostate cancer is the most common cancer afflicting American men. The American Cancer Society estimates that over 180,00 new cases will be diagnosed in the U.S. in the year 2000 alone, and that nearly 32,000 people will die from the disease. Prostate cancer is second only to lung cancer as the leading cause of cancer death in men, accounting for roughly 11%. 
     Prostate cancer is defined as malignant tumor growth within the prostate gland. Its cause is unknown, although high dietary fat intake and increased testosterone levels are believed to be contributory factors. A letter scale (“A” through “D”), which accounts for the location of the cancer, is commonly used to classify the stage of disease. In Stage A, the tumor is not palpable but is detectable in microscopic biopsy. Stage B is characterized by a palpable tumor confined to the prostate. By Stage C, the tumor extends locally beyond the prostate with no distant metastasis. By Stage D, cancer has spread to the regional lymph nodes or has produced distant metastasis. 
     In the early stages, prostate cancer is most commonly treated by prostate removal or by brachytherapy. More advanced cases are treated by hormonal manipulation or orchiectomy to reduce testosterone levels and curb spreading of the disease, by chemotherapy, or by external beam radiation therapy. 
     With regard to treatment of early stage prostate cancer, the state of the art has several drawbacks. Radical prostatectomy is often recommended for treatment of localized stage A and B prostate cancers. Under general or spinal anesthesia, an incision is made through a patient&#39;s abdomen or perineal area, and the diseased prostate is removed. The procedure is lengthy, especially if a lymph node dissection is simultaneously performed, and requires a hospital stay of 2-5 days. Possible complications include impotence and urinary incontinence. 
     Internal radiation therapy or brachytherapy has recently been modified and holds great promise for the treatment of early stage prostate cancer. Radioactive pellets or seeds of, for example, iodine-125, gold-198, palladium-103, ytterbium-169, or iridium-192, are deposited directly into the prostate through needle placement. Imaging tests, such as transrectal ultrasound, CT scans, or MRI, are used to accurately guide placement of the radioactive material. Advantageously, radiation is administered directly to the prostate with less damage to surrounding tissues, requiring a significantly smaller radiation dosage as compared to external beam radiation therapy. Furthermore, the procedure need only be performed once. Complications include a lower, yet still significant, incidence of impotence and urinary incontinence, compared to prostate removal procedures. 
     The radioactive seeds are placed inside thin needles, which are inserted through the skin of the perineum (area between the scrotum and anus) into the prostate. U.S. Pat. No. 5,928,130 to Schmidt provides a slightly modified example of such a needle device. Each needle is slowly retracted with a spinning motion by a first practitioner while a plunger within the needle, and proximal of the radioactive seeds, is held stationary by a second practitioner. The plunger keeps the seeds in place during retraction of the needle, while rotation of the needle during retraction prevents jamming of the seeds while delivering the seeds in a line within the prostate. 
     The seeds, which are permanently implanted, give off radiation for weeks or months. Their presence causes little discomfort, and they are left in the prostate after decay of the radioactivity. For about a week following needle insertion, patients may experience pain in the perineal area, and urine may have a red-brown discoloration. 
     Although, when performed correctly, radioactive seed implantation may provide several benefits, compared to prostate removal and other techniques, current surgical apparatus and methods for delivering the seeds to target locations within the prostate are somewhat crude and are subject to practitioner error. The procedure requires two practitioners working cooperatively to deliver the seeds. The depth to which the plunger is inserted into the needle, in the loaded and advanced states, is critical but crudely measured. The plunger and needle may accidentally move relative to one another during needle insertion or seed delivery, causing improper positioning of deposited seeds. The needle is somewhat flexible and should be inserted quickly to minimize bending at its distal tip, but this is often not done due to inexperience or technical ability of the practitioners, or to avoid potential relative movement between the plunger and the needle. 
     Attempts have been made to address various aspects of these concerns. For example, U.S. Pat. No. 4,815,449 to Horowitz describes an absorbable member with seeds spaced within the member to facilitate proper spacing during delivery. U.S. Pat. No. 4,700,692 to Baumgartner describes apparatus for delivering all of the seeds simultaneously. PCT document WO 99/20337 to Rydell describes a gun-like apparatus for delivering seeds once the needle has been inserted into the prostate. 
     While each of these devices may provide some benefit over the prior art, none satisfactorily addresses the shortcomings of current techniques. In view of the drawbacks associated with previously-known methods and apparatus for brachytherapy, it would be desirable to provide methods and apparatus that overcome such drawbacks. 
     It further would be desirable to provide methods and apparatus that allow efficient preparation of the apparatus for therapeutic administration. 
     It still further would be desirable to provide methods and apparatus for administering brachytherapy that require only one medical practitioner. 
     It further would be desirable to provide methods and apparatus that yield easy measurement and maintenance of plunger depth within the needle. 
     It would also be desirable to provide methods and apparatus for brachytherapy that allow rapid insertion of the needle while maintaining the distance between the needle and plunger. 
     SUMMARY OF THE INVENTION 
     In view of the foregoing, it is an object of the present invention to provide methods and apparatus for brachytherapy that overcome drawbacks associated with previously-known methods and apparatus. 
     It is also an object of the present invention to provide methods and apparatus that allow efficient preparation of the apparatus for therapeutic administration. 
     It is another object to provide methods and apparatus for brachytherapy that require only one medical practitioner. 
     It is yet another object to provide methods and apparatus that yield easy measurement and maintenance of plunger depth within the needle. 
     It still further is an object of the present invention to provide methods and apparatus for brachytherapy that allow rapid insertion of the needle while maintaining the distance between the needle and plunger. 
     These and other objects of the present invention are accomplished by providing methods and apparatus for brachytherapy treatment of prostate cancer comprising a specialized housing that maintains needle/plunger spacing, provides easy measurement of plunger depth within the needle, requires only one practitioner to operate, and enables rapid needle insertion. The plunger is fixed with respect to the housing, while the needle is removably coupled to the housing. Either the plunger or the housing wall is threaded to receive the needle. Measurement indicia on the needle simplify determination of plunger depth within the needle. A locking mechanism maintains plunger depth during needle insertion. To deliver seeds, the needle is rotated while the housing is held stationary, causing the needle to retract along the screw thread. 
     In a preferred embodiment, the needle is rotated manually. Alternatively, the needle may attach to a swivel that rotates the needle by pulling it proximally along the screw thread. In a still further embodiment, a pull tab may be used to rotate the needle. 
     Methods of using the present invention are also provided. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Additional objects and advantages of the invention will be apparent from the following description, the accompanying drawings and the appended claims, in which: 
     FIG.1 is a schematic view of a prior art method of performing brachytherapy; 
     FIGS. 2A-2G are schematic views detailing the prior art method in greater detail; 
     FIG. 3 is an isometric exploded view of a first embodiment of apparatus constructed in accordance with the present invention; 
     FIG. 4 is a cross-sectional view of the apparatus of FIG. 3; 
     FIG. 5 is a cross-sectional view of an alternative embodiment of apparatus of the present invention; 
     FIG. 6 is an isometric exploded view of a further alternative embodiment of the present invention comprising a swivel; 
     FIG. 7 is a cross-sectional view of the apparatus of FIG. 6; 
     FIG. 8 is an isometric exploded view of a still further alternative embodiment with a syringe swivel; 
     FIG. 9 is a cross-sectional view of the apparatus of FIG. 8; 
     FIG. 10 is an isometric exploded view of yet another alternative embodiment of apparatus constructed in accordance with the present invention comprising a pull tab; 
     FIG. 11 is a cross-sectional view of the apparatus of FIG. 10; and 
     FIG. 12 is a detail view of the cross-section of FIG.  11 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention provides methods and apparatus for improved administration of brachytherapy. More particularly, the present invention provides a threaded housing with locking mechanism that maintains the position of the plunger with respect to the needle and provides controlled retraction of the needle. 
     Referring now to FIGS.  1  and  2 A- 2 G, the prior art method of performing brachytherapy is described. The method and apparatus are as taught by Peter Grimm, DO, in a pamphlet entitled, “Ultrasound Guided Implantation of the Prostate: A Practical Review Course.” As seen in FIG. 1, brachytherapy apparatus  50  comprises transrectal ultrasound probe  52 , guide block  54 , needle  56 , plunger  58 , and radioactive seeds  60 . Ultrasound probe  52  is advanced through a patient&#39;s rectum R to facilitate imaging of the patient&#39;s prostate P. Prostate P surrounds the urethra U and is just proximal of the bladder B. Needle  56 , loaded with seeds  60  and plunger  58 , is advanced through the patient&#39;s perineum Pe into prostate P, where needle  56  is retracted and seeds  60  are delivered to the patient. 
     With reference to FIGS. 2, a previously known seed delivery method is described in greater detail. Needle  56  has proximal end  62 , sharpened distal end  64 , and a lumen extending therebetween. Proximal end  62  comprises hub  66  for easy grasping of the needle. The opening at the distal tip of needle  56  is initially filled with bone wax that melts when placed inside the body. The needle lumen typically is filled in an alternating pattern of seeds  60  and spacers  68 . 
     Once a required number of seeds have been loaded, plunger  58  is inserted into proximal end  62  of needle  56  and is advanced distally until it abuts the proximal-most seed. Plunger  58  comprises grip  70  at its proximal end. The distance from the distal end of grip  70  to the distal end of the plunger is equal to the length of needle  56 . Thus, since seeds  60  and spacers  68  are of known length, measurement of D 1 , the distance plunger  58  extends proximally of needle  56  in the loaded configuration, provides verification of the number of seeds  60  located within the needle lumen, as seen in FIG.  2 A. 
     Ultrasound probe  52  provides signals that are converted by a previously known ultrasound system to display ultrasonic image  72  of base plane BP, which is located tangent to the distal surface of prostate P. All positions within the prostate are determined relative to base plane BP. With seeds  60  loaded into needle  56  and the distance D 1  verified; the needle, seeds, and plunger  58  are inserted through guide block  54  and into the patient until needle  56  appears as target T on ultrasonic image  72  and extends about a centimeter distal of base plane BP, as depicted in FIG.  2 B. The apparatus is then retracted until target T disappears (FIG. 2C) and is once again advanced until target T just reappears (FIG.  2 D). All the while, distance D 1  is maintained. 
     Once needle  56  is aligned with base plane BP, a distance D 2  between the proximal face of guide block  54  and the proximal face of hub  66  is established, as shown in FIG.  2 E. D 2  serves as the reference distance for determining insertion depth for all subsequent needle insertions. A first medical practitioner then holds needle  56  stationary while a second medical practitioner advances the first seed  60  to the distal tip of the needle with plunger  58 , as depicted in FIG.  2 F. The advancement distance equals the length BW of the bone wax used to plug the tip. 
     Finally, the second medical practitioner holds plunger  58  stationary while the first practitioner rotates and proximally retracts needle  56  to sew the seeds in a line within prostate P, as shown in FIG.  2 G. The needle and plunger are then removed from the patient, and the procedure is repeated at other locations as necessary. 
     With reference now to FIGS. 3 and 4, a first embodiment of apparatus constructed in accordance with he present invention is described. Apparatus  100  comprises housing  102 , plunger  104 , needle  106 , and lock  108 . Lock  108  is configured to be received in slot  110  of needle  106 . Needle  106  further comprises lumen  107 , male screw thread  112 , and measurement indicia  113 . Housing  102  comprises lumen  114 , in which plunger  104  is rigidly fixed, threaded bore  116  with female screw thread  118 , and standard bore  120 . When assembled, male thread  112  of needle  106  engages female thread  118  of housing  102 , and plunger  104  extends into lumen  107  of needle  106 . 
     A method of using apparatus  100  in accordance with the principles of the present invention is now described. Needle  106 , loaded with seeds  60  and spacers  68  in lumen  107 , is inserted through bore  120  until male thread  112  of needle  106  just mates with female thread  118  of bore  116 . 
     At this point, plunger  104  extends partially within lumen  107  of needle  106 , so that plunger  104  just contacts the proximal-most seed  60 . Also, slot  110  of needle  106  is just distal of the opening to bore  120 . Lock  108  is removably received within slot  110  and ensures that plunger  104  is not advanced distally with respect to needle  106  until the needle is inserted within a patient&#39;s prostate. Lock  108  thereby ensures that distance D 1  between the proximal end of needle  106  and proximal base  122  of bore  116  (which is roughly equal to the length of bore  116 ) is maintained during insertion. Since D 1  is positively maintained during insertion, the apparatus of the present invention should advantageously cause medical practitioners to be less reticent about rapid insertion of the needle into a patient. 
     Measurement indicia  113  of needle  106  permit easy determination of distance D 1 , and, thus, verification of the number of seeds  60  contained within lumen  107  of needle  106 . As an illustrative example, D 1  is such that the proximal-most indicator mark  113  extends beyond the distal end of housing  102 . If this marking is ‘0’, the proximal end of needle  106  is in contact with proximal base  122  of bore  116 . If it is ‘1’, there is one centimeter of separation, etc. 
     After insertion of the needle into the patient, lock  108  is removed, thereby allowing relative movement between plunger  104  and needle  106 . Initially, needle  106  is held stationary while housing  102  is rotated to advance the distal-most seed  60  to the tip of needle  106 . Then, housing  102  is held stationary while needle  106  is rotated. This causes needle  106  to retract proximally along thread  118  while plunger  104  remains stationary, thereby controllably sewing seeds  60  in a row in the prostate. Since the sewing motion is simplified, compared to prior art apparatus  50 , only one practitioner is required to perform the procedure. 
     The distance D 1  may be altered as needed by altering the length of bore  116  and, thus, the length of housing  102 . Alternatively, bore  116  may be of a standard length in excess of that required for D 1 . Needle  106  then may comprise multiple slots  110  along its length to receive lock  108 . The distance D 1  then may be fixed at a variety of lengths. 
     Referring now to FIG. 5, an alternative embodiment of the present invention is disclosed. Apparatus  130  comprises housing  132 , plunger  134 , needle  136 , and lock  138 . Lock  138  is configured to be received in slot  140  of needle  136 . Needle  136  further comprises lumen  137 , female screw thread  142  along the walls of the proximal portion of its lumen, and measurement indicia (not shown). Plunger  134  comprises male screw thread  144  along its proximal end. Housing  132  comprises lumen  146 , in which plunger  134  is rigidly fixed, and bore  148 . 
     Needle  136 , loaded with seeds  60  and spacers  68 , is inserted through bore  148  until female thread  142  of needle  136  just mates with male thread  144  of plunger  134 . Thus, apparatus  130  is similar to apparatus  100 , except that needle  136  threadingly engages plunger  134 , rather than the housing. 
     With reference to FIGS. 6 and 7, a further alternative embodiment of the present invention is detailed. Apparatus  150  comprises housing  152 , plunger  154 , needle  156 , and lock  158 . Lock  158  is configured to be received in slot  160  of needle  156 . Needle  156  further comprises lumen  157 , male screw thread  162 , measurement indicia  163 , and swivel  164  including cord  166 . Housing  152  comprises lumen  168 , in which plunger  134  is rigidly fixed; threaded bore  170  with female screw thread  172 ; and a standard bore (not shown) similar to bore  120  of apparatus  100 . Housing  152  further comprises cord bore  174  through which cord  166  passes out of housing  152 . 
     In use, cord  166  is threaded through cord bore  174  and the male and female screw threads are engaged as described hereinabove with reference to apparatus  100 . Needle  156  then may be retracted proximally with respect to housing  152  by holding the housing stationary and pulling cord  166  proximally. The needle rotates and retracts within the screw thread, while swivel  164  moves proximally in bore  168 , but does not rotate. 
     Referring now to FIGS. 8 and 9, a still further alternative embodiment of the present invention is described. Apparatus  180  comprises housing  182 , plunger  184 , needle  186 , syringe swivel  188 , and lock  190 . Lock  190  is configured to be removably received in slot  192  of needle  186 . Housing  182  comprises lumen  194 , in which plunger  184  is rigidly fixed; threaded bore  196  with female screw thread  198 ; and a standard bore (not shown) similar to bore  120  of apparatus  100 . Housing  182  is formed in two halves  200  and  202  joined at hinge  204 . Hinge  204  preferably is a ‘living hinge’ as may be constructed using polymers, such as polypropylene, and previously known manufacturing techniques. Needle  186  further comprises lumen  187 , male screw thread  206 , measurement indicia  207 , and swivel attachment  208 . Syringe swivel  188  comprises swivel attachment  210 , bore  212 , and enlarged proximal end  214 , and is formed in two halves  216  and  218  joined at hinge  220 . As with hinge  204 , hinge  220  preferably comprises a living hinge. 
     Housing  182  and syringe swivel  188  are opened at hinges  204  and  220 , respectively, so that swivel  20  attachments  208  and  210 , and the male and female screw threads, engage each other. The housing and syringe swivel are then closed. After insertion into a patient, needle  186  may be retracted proximally with respect to housing  182  by holding the housing stationary and retracting enlarged end  214  of syringe swivel  188  proximally. Needle  186  rotates and retracts within the screw thread while syringe swivel  188  moves proximally but does not rotate. 
     With reference to FIGS. 10-12, yet another alternative embodiment of the present invention is described. Apparatus  230  comprises housing  232 , plunger  234 , needle  236 , pull tab  238 , and lock  240 . Lock  240  is configured to be received in slot  242  of needle  236 . Needle  236  further comprises lumen  237 , male screw thread  244 , and measurement indicia  245 . Housing  232  comprises lumen  246 , in which plunger  234  is rigidly fixed; threaded bore  248  with female screw thread  250 ; standard bore  252 ; and slot lumen  254  configured to receive pull tab  238 . Slot lumen  254  is preferably located just off center of the radial axis of housing  232  and communicates with bore  252 . Pull tab  238  comprises grip  256  and female threads  258 . 
     Needle  236 , loaded with seeds  60  and spacers  68 , is inserted through bore  252  into threaded bore  248  until male thread  244  of needle  236  mates with both female screw thread  250  of housing  232  and female threads  258  of pull tab  238 . As most clearly illustrated in FIG. 11, needle  236  then may move relative to housing  232  simply by holding housing  232  stationary and pulling or pushing pull tab  238 . Pulling tab  238  causes needle  236  to rotate and proximally retract in a controlled fashion along screw thread  250  of housing  232 , and along threads  258  of pull tab  238 , thereby sewing the seeds along the needle track. 
     Although particular embodiments of the present invention have been described above in detail, it will be understood that this description is merely for purposes of illustration. Specific features of the invention are shown in some drawings and not in others; this is for convenience only, and any feature may be combined with another in accordance with the invention. Further variations will be apparent to one skilled in the art in light of this disclosure and are intended to fall within the scope of the appended claims.