Device and method for loading radioactive seeds in needles

Abstract: A modular device for implanting radioactive seeds in an animal body through a needle implanted in the body. The device comprises an electronic control device controlling a pushing drive, a seed and spacer supply container, a multichannel holder for seed-spacer trains. A tube connects between the multichannel holder and the needle. The needle is retractable by retracting means coupled to the needle. Optionally the retracting means are controlled by the electronic control device. The device may also be embodied in a combination of a seed loading module in which trains of seeds are loaded in channels in a removable multichannel holder and a seed implanting module in which trains of seeds from a multichannel holder are pushed into needles implanted in the body. Parts that may be contaminated with blood are made removable for sterilization or disposal.

Description: The invention relates to a device for implanting radioactive seeds in a desired pattern in an animal body through a number of needles, said number being one or more, implanted in the animal body. The invention also relates to a method for loading radioactive seeds in a number of needles. BACKGROUND OF THE INVENTION A device for implanting radioactive seeds in an animal body is known from Journal of Brachytherapy International 1998;14:21-27. Therein is described a device in which under ultrasound guidance using an ultrasound probe and using a first template implant needles, hereinafter needles, are placed in a prostate gland. Under fluoroscopy the positions of the needles are checked. For every individual needle the length of the train of seeds is determined. The trains of seeds are placed into the needles with custom-made stylets. Thereafter a second template is attached to a stepping unit in the same way as the ultrasound probe. The ends of the stylets are placed in the second template at the same positions as the needles in the first template. The correct distance between the second template and the ends of the needles is established and the needles are retracted over the stylets manually. The described method of implanting is cumbersome in that a lot of specialized and delicate tasks have to be fulfilled manually. Acting like this it is not possible to reach a high degree of accuracy in the placement of the seeds. The determination of the desired placements of the seeds can be done with very high accuracy based upon the known physics of the radioactive radiation emitted by the seeds and the geometry of the prostate gland. Such determination of desired placement usually is done by means of a computer programmed with a known therapy planning program. One such program is marketed under the trademark PLATO by Nucletron BV of the Netherlands. Nevertheless the manual placement of the seeds makes it necessary to recheck the number of seeds introduced and if necessary to introduce additional seed trains. In United States Patent No. 5,139,473 a remote controlled after loader apparatus is disclosed for pushing one, single radioactive seed through a catheter tube using a wire. The wire (and hence the single radioactive source) is advanced and retracted out and in the apparatus by means of drive means, which drive means are controlled by electronic control means. BRIEF DESCRIPTION OF THE INVENTION It is an object of the invention to provide a device for implanting radioactive seeds in a desired pattern in an animal body through a number of needles implanted in the animal body, the number being one or more, according to claim 1. Advantageous embodiment of the device according to the invention as disclosed in the dependent device claims 2-32. It is also an object of the invention to provide a method for loading radioactive seeds in a number of needles according to method claim 33. The invention shall now be described in more detail with the help of the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS In the drawing, Fig. 1 shows a very schematic and simplified device according to the invention; Fig. 2 shows a schematic view of an embodiment of a first device according to the invention; Figs. 3A and 3B show details of the device shown in Fig. 2; Fig. 4A shows a schematic view of a first embodiment of a seed loafing module; Fig. 4B shows a schematic view of a second embodiment of a seed loading module; Fig. 5 shows a schematic view of a first embodiment of a seed implanting module; Fig. 6 shows a first embodiment of means for retracting a needle; Fig. 7 shows a second embodiment of means for retracting a needle; Fig. 8 shows a third embodiment of means for retracting a needle; Fig. 9 shows an embodiment of another device according to the invention; Fig. 10 shows a top view of a device as shown in Fig. 9; Fig. 11 shows a view of various parts of a device shown in Fig. 9; Fig. 12 shows a front view of a seed supply container; Fig. 13 shows a view along the line A-A in Fig. 12; Fig. 14 shows a detail of Fig. 13; Fig. 15 shows a seed- and a spacer supply container; Fig. 16 shows a first view of a connection between the supply containers and the pushing drive module; Fig. 17 shows a second view of a connection between the supply containers and the pushing drive module; Fig. 18 shows an exploded view of the pushing drive module; Fig. 19 shows a front view of the pushing drive module; Fig. 20 shows a view along the line A-A in Fig. 19; Fig. 21 shows part of the assembly module; Fig. 21A shows a detail of Fig. 21; Fig. 22 shows a detail of a part of an assembly module; Figs. 23A and 23B show views of the retracting mechanism in the embodiment according to Fig. 9; Fig. 24 shows a tube with connector; Fig. 25 shows a third embodiment of a seed loading module; Fig. 26 shows a top view of the part shown in Fig. 25; Fig 27 shows a second embodiment of a seed implanting module. DESCRIPTION OF PREFERRED EMBODIMENTS It is to be noted that the following description will be made with respect to treatment of a prostate gland. However, the invention may be used in far more applications in which (radioactive) seeds are deposited in other parts of an animal body. Fig. 1 shows in very schematic form various elements of a device for implanting radioactive seeds into a prostate gland. A patient 1 is shown lying in lithotomy position on a table 2. Fixedly connected to the table 2 is a stepper unit 3. Stepper unit 3 comprises a drive to move movable tables 4 and 4a stepwise. Connectable to table 4 is a template 5. By means of a holder 6 a transrectal ultrasound probe 7 is fixedly connectable to table 4a. A needle 9 is used for fixing the prostate gland 11 in position relative to the template 5. A number of needles 10 is fixed into position through the template 5 in the prostate gland 11. The template 5 determines the relative positions of the needles 10 in two dimensions. The needles 10 are open at their distal ends and are sealed of by a plug of biocompatible, preferably bio-absorbable wax. In a first embodiment seed loading unit 8 is connectable to the table 4. In a second embodiment seed loading unit 8 is a stand alone unit. A well-known therapy planning module 12a is provided for determining the number and relative positions of seeds in each needle for implantation in the prostate gland 11. Such therapy planning module 12a usually comprises a computer programmed with a therapy planning program. One such a therapy planning program is marketed under the trademark PLATO by Nucletron BV of the Netherlands. Other such programs are also known. The therapy planning module 12a is connected to the seed loading unit 8 through a control device 12 for controlling the number of seeds for each needle. Control device 12 may be a separate device or may be an integrated part either of the seed loading unit 8 or of the therapy planning module 12a or may be embodied in the software of the therapy planning module 12a or of the seed loading unit 8. In one embodiment control device 12 comprises a programmed microprocessor, preferably a 16-bit version. Such a microprocessor may be a Siemens 166 or a Philips 8051 EA or one of another manufacturer. Operation of the device shown in Fig. 1. A patient 1 is under spinal or general anesthesia and lying on the operating table 2 in lithotomy position. Trans-rectal ultrasound probe 7 is introduced into the rectum and the probe is connected to the stepper unit 3 and table 4 through holder 6. On an image screen, well known, an image may be seen of the inside of the patient in particular of the prostate gland 11 as seen from the point of view of the ultrasound probe 7. The template 5 is attached to the stepper unit 3. Thereby the correlation of the ultrasound image geometry and the template 5 is guaranteed. The prostate gland 11 is fixed relative to the template and the stepper unit 3 and the ultrasound probe by means of one or more needles 10. Subsequently further needles 10 are introduced in the body and the prostate gland under ultrasound guidance one by one. Moving the ultrasound probe with the stepper unit 3 longitudinally within the rectum controls the needle depths. After all needles 10 have been placed their positions relative to the prostate gland 11 are determined in at least one of several known ways. In a known way the therapy planning module 12a determines how the needles 10 are to be placed in the prostate and how many radioactive seeds are to be placed in what order in each of the needles 10. The information about the desired placement of the radioactive seeds in the needles 10 is used to control the seed loading unit 8. Usually the seeds are spaced from each other by spacers. For example seeds of 1 cm length may be spaced by spacers also of 1 cm length. Other measures of seeds and spacers are imaginable. A set of seeds and spacers loaded or to be loaded into a needle will be called a seed train or a train of seeds or a seed-spacer train. For each needle 10 the configuration of an applicable seed-spacer train is determined by the therapy planning module 12a. The seed loading unit 8 is controlled by the control device 12 to make up a seed-spacer train for each needle 10. The making up of a specific seed-spacer train will be described hereinbelow later on. Once a seed-spacer train is to be or has been made up for a specific needle a connection is made to the specific needle. After the seed-spacer train has been made up it is urged into the specific needle by a pushing drive that is part of the seed loading unit 8. Since all elements of the seed loading unit 8 and the needles 10 and their interconnections are of specific pre-known dimensions, which may or may not be the same for all like elements and such dimensions have been made known, e.g. pre-loaded in or pre-entered via a keyboard 12b to the control device 12 the pushing drive pushes with a pushing wire the seed-spacer train just until it reaches the distal end of the specific needle. Subsequently the pushing wire is fixed in position and the specific needle is retracted over a distance equal to or slightly greater than the length of the seed-spacer train in it. Thereby the wax plug and the seed-spacer train are introduced in the prostate gland 11. Next the pushing wire is withdrawn into the seed loading unit 8 for pushing a next seed-spacer train into the prostate gland 11. The delivery of seed-spacer trains in the prostate gland continues until each needle 10 has been retracted and a number of seed-spacer trains equal to the number of needles 10 has been delivered in the prostate gland 11. Subsequently the seed loading unit 8 is disconnected from the stepper unit 3 and the needles 10 are retracted from the patient completely. After the geometry of the implanted seeds has been checked under fluoroscopy or another method of checking the presence of the seeds in the prostate gland 11 and removal of the ultrasound probe 7 the patient 1 is hospitalized for recovery. Fig. 2 shows a schematic representation of a first embodiment of a seed loading device 8 according to the invention. Inside a housing 20 there is provided a platform 21. The platform 21 is fixed to a wheel 22. Along the rim of the wheel 22 teeth are present that mesh with teeth on a shaft 23. Toothed wheel 22 is rotatable about a shaft 32. Shaft 23 is driveable by a motor 24. On the platform 21 a motor 25 is placed. A shaft 26 of motor 25 connects detachably to a pushing drive 27. The pushing drive 27 connects through a tube 28 to seed and spacer supply container 29. Supply container 29 is detachably fixed to platform 21. A seed and a spacer are indicated schematically as 29a and 29b respectively. Supply container 29 comprises a channel 59, shown in Figs. 3A and 3B that is longitudinally aligned with tube 28. Fixed to the supply container 29 is a further tube 30 that is longitudinally aligned to the channel 59 in supply container 29. Tube 30 fits through a corresponding opening in wheel 22 and stretches until it reaches multichannel holder 31. Multichannel holder 31 is detachably fixed in housing 20 and supported by a support element 31a. Multichannel holder 31 comprises a number of bores one of which is shown as 33. The bores in multichannel holder 31 are arranged in circular order such that upon rotation of wheel 22 tube 30 sequentially aligns with the bores in multichannel holder 31. A plate 34 includes a number of openings. The openings in plate 34 are also arranged in circular order. Plate 34 is switchable between a first and a second position about shaft 35 by means of a motor 36 and a shaft 37. Instead of a motor 36 and shaft 37 also an electromagnet (not shown) may be used to switch plate 34 from its first to its second position and vice versa. Shaft 37 meshes with teeth on the circumference of plate 34. In the first position the openings in plate 34 coincide with the bores 33. In the second position all bores 33 are closed of by plate 34. Longitudinally aligned with bore 33 is a tube 38. Tube 38 fits slideably inside a needle retraction tube 39. A distal end of tube 38 is inside tube 39. tube 39 is in longitudinal alignment with bore 45a in needle 44. Needle retraction tube 39 is movable back and forth between a first and a second position. The first position is shown in phantom whereas the second position is shown in drawn lines in Fig. 2. A needle retraction mechanism is shown schematically as comprising a toothed bracket 40, a toothed wheel 41 and a drive 42 for the toothed wheel 41. Retraction tube 39 extends through the housing 20 and ends in a coupling 43. Coupling 43 couples retraction tube 39 to a needle 44. Needle 44 at its distal end is shown provided with a plug of wax 45. Housing 20 is provided with appropriate closeable openings (not shown) for installing pushing drives 27, supply containers 29, multichannel holders 31 and tubes 38. Housing 20 is provided with a number of tubes 38, retraction tubes 39, toothed brackets 40, toothed wheels 41 and drives 42 for the toothed wheels 41 which number is equal to the number of channels 33 in multichannel holder 31. Before starting to use seed loading unit 8 pushing drive 27 is installed on shaft 26. Also installed before use are supply container 29 with tube 30, a multichannel holder 31 and a tube 38 with corresponding coupling 43. Pushing drive 27, supply container 29, tube 30, multichannel holder 31, tube 38 coupling 43 and needle 44 all are sterilized before being used and installed. Under control of the control device 12 the channels 33 in the multichannel holder 31 are filled with appropriate seed-spacer trains. Filling of the channels 33 is done by first loading a seed 49 and a spacer 48 into channel 59 in the supply container 29. Subsequently a pushing wire present in the pushing drive 27 is moved by motor 25 to push the spacer-seed set present in channel 59 through tube 30 into channel 33. It may be noted that a spacer seed set may also consist of only a spacer or only a seed depending on the required radiation distribution as determined by the therapy planning module 12a. Plate 34 has been switched under control of control device 12 meanwhile such that the openings therein do not coincide with the channels 33 in multichannel holder 31. A plurality of needles 44, i.e. a first one, a second one, a third one, a fourth one etc. has been introduced into the body and has been connected through corresponding first, second, third, fourth etc. couplings 43 to corresponding first, second, third, fourth etc. tubes 39 respectively. Once all seed-spacer trains have been set up in the channels 33 wheel 22 is rotated to bring tube 30 in longitudinal alignment with a first one of the channels 33 which is in longitudinal alignment with a first one of the tubes 38 which is connected through a first tube 39 and a first coupling 43 to a first needle 44. Channel 59 now is free of any seeds and spacers. Under control of the control device 12 the pushing wire of pushing drive 27 enters tube 28, channel 59, tube 30, first channel 33 and pushes forward the seed-spacer train out of the first channel 33 into the first tube 38 and further through the first coupling 43 into the first needle 44 until it reaches the plug of wax 45 in the first needle. The pushing wire is fixed in position then whereby the first seed-spacer train remains fixed between plug 45 and the distal end of the pushing wire. After that first motor 42 is activated to turn first wheel 41 and thereby move first bracket 40 in the direction of arrow A in Fig. 2. First bracket 40 pushes against first arm 60 of first retraction tube 39. Thereby first retraction tube 39 is moved in the direction of arrow A in Fig. 2. Since first retraction tube 39 is connected to first needle 44 that first needle 44 is retracted in the direction of arrow A. As a consequence the plug of wax and the first seed-spacer train are introduced in the prostate gland 11. Then the pushing wire is retracted at least as far as the point at which the distal end has entered the tube 30. Then the wheel 22 is rotated for the tube 30 to come into longitudinal alignment with a second channel 33 with a second seed-spacer train in it. Then the whole series of actions described hereinbefore with respect to the first seed-spacer train takes place with respect to the second seed-spacer train. Thereafter all steps are repeated for a third, fourth etc. seed-spacer train until all seed-spacer trains present in channels 33 have been introduced in the prostate gland 11. It is to be noted that needle 44 is an open needle. As a consequence blood may have entered bore 45a and have come into contact with the pushing wire. Various parts may have been contaminated with blood by the pushing wire such as the coupling 43, the tube 38, the channels 33, the tube 30, the supply container 29, the tube 28 and the pushing drive 27. It may also be that blood has passed past the pushing wire into the bore 46, the coupling 43, the tube 38, the channels 33, the tube 30, the supply container 29, the tube 28 and the pushing drive 27. Due to the modular build up of the seed loading unit 8 after of all the seed-spacer trains have been delivered all the elements mentioned that might have been contaminated with blood can be taken out of the seed loading unit 8 either for sterilization or for disposal, as appropriate. Figs. 3A and 3B show in schematic and simplified form a module comprising a supply container 29 in front view and in side view respectively. Supply container 29 comprises two reservoirs 46 and 47 respectively. Reservoir 46 is for spacers 48 and reservoir 47 is for seeds 49. For clarity only limited numbers of spacers 48 and seeds 49 are shown. In practice several tens of spacers and seeds are present in reservoirs 46 and 47 respectively. The reservoirs 46 and 47 comprise springs 50 and 51 and plungers 52 and 53 respectively. Shown for the spacers 48 is a drive 54. Drive 54 is arranged upon activation to push member 55 in the direction of the arrow 56 against the force exerted by a spring 57. Thereby an opening 58 comes in line with reservoir 46 thereby allowing a spacer 48 to enter channel 59. Indicated by corresponding reference numerals but not shown is a same mechanism 54a, 55a, 56a, 57a and 58a attached to reservoir 47 for making a seed 49 enter channel 59. In operation supply container 29 while outside the housing 20 is filled under sterile conditions with seeds and spacers in reservoirs 46 and 47. Thereafter a filled supply container 29 is placed in the seed loading unit 8. Fixedly connected to housing 20 are drives 54 and 54a. Upon placement of supply container 29 push members 55 and 55a come into contact with drives 54 and 54a respectively. The position of push member 55 shown in Fig. 3A is the rest position. In case a spacer/seed has to be added to the seed-spacer train that is being configured under control of control device 12 drive 54/54a is activated to push push member 55/55a against the force of spring 57/57a such that opening 58/58a opens up channel 59 to the spacer/seed 61/61a on top of the stack. Under the force of spring 50/51 the spacer/seed 61/61a on top of the stack is pushed into channel 59. Thereafter the drive 54/54a is deactivated whereby spring 57/57a pushes push member 55/55a back to its rest position. The spacer/seed 61/61a may now be pushed into channel 33 of the multichannel holder 31 by means of the push wire of push drive 27. After retraction of the push wire of the push drive 27 channel 59 is free to receive a next spacer/seed. Figs. 4A, 4B and 5 show two embodiments of a seed loading module and an embodiment of a seed implanting module as modular parts of a device according to the invention. In that embodiment a spatial division has been made between a module dedicated to loading a multichannel holder 31 with seed-spacer trains and a module dedicated to implanting the seed-spacer trains from the multichannel holder 31 in the body. In Figs. 4A, 4B and 5 like elements have been identified by the same reference numerals, which reference numerals also are identical to those used in Fig. 2 for like elements. In Fig. 4A housing 20 is equipped with a hinged cover 20a allowing easy replacement of supply container 29 and multichannel holder 31. Multichannel holder 31 is filled with seed-spacer trains in like manner as described in relation to Fig. 2. After all relevant channels 33 in multichannel holder 31 have been filled with appropriate seed-spacer trains cover 20a is opened thereby giving access to multichannel holder 31 for evacuation thereof and placement in a device as to be described hereinbelow with reference to Fig. 5. In Fig. 4B platform 21 is fixedly mounted to housing 20. Toothed wheel 22 is rotatable on shaft 32. The teeth of wheel 22 mesh with teeth of a shaft 23 that is rotatable by a motor 24. Wheel 22 is provided with an opening such that tube 30 extends uninterruptedly up until multichannel holder 31. Due to the presence of the opening wheel 22 may be rotated without breaking the tube 30. Multichannel holder 31 is provided with a central opening meshing with shaft 32 upon insertion of multichannel holder 31 through opened hinged cover 20a. For better stability of multichannel holder 31 one or more support wheels 31d on shafts 31c supported by shaft support elements 31b may be present. Since supply container 29 now is fixed relative to housing 20 multichannel holder 31 is rotated by motor 24 through shaft 23 and wheel 22 and shaft 32 to place a channel 33 in longitudinal alignment with tube 30. As has been described hereinbefore in relation to Fig. 2 seed-spacer trains are made up in channels 33 of multichannel holder 31. Each time a channel 33 has been filled with an appropriate seed-spacer train motor 24 is activated to rotate multichannel holder 31 until the next channel 33 to be filled is in longitudinal alignment with tube 30. After all relevant channels 33 in multichannel holder 31 have been filled with appropriate seed-spacer trains cover 20a is opened thereby giving access to multichannel holder 31 for evacuation thereof and placement in a device as to be described hereinbelow with respect to fig. 5. Fig. 5 shows a seed implanting module as it may be used with a multichannel holder 31 according to one of Figs. 4A and 4B. Fig. 5 is almost identical to Fig. 2, though supply container 29 is not present and tubes 28 and 30 are merged together into a single tube. The housing 120 is provided with a hinged cover 120a. In operation of the device shown in Fig. 5 the hinged cover 120a is opened to give access to its inner space. A multichannel holder 31 provided with channels 33 loaded with appropriate seed-spacer trains may then be brought into the position shown in Fig. 5. After multichannel holder 31 has been brought into position hinged cover 20a is closed and motor 36 is operated to turn wheel 34 such that the openings in wheels 34 are in alignment with the channels 33 of the multichannel holder 31. Reference is had to the description in relation to Fig. 2 regarding to operation of the device. Fig. 6 shows a first embodiment of a means for retracting tube 39. An element 61 is fixedly connected to tube 39. Element 61 is slideably arranged over bar 62. In parallel to tube 39 bar 62 is fixedly mounted to housing 20 as schematically illustrated by bracket 63. Element 61 is provided with a hole (not shown) with screw-thread. Spindle 64 passes through the hole with screw-thread in element 61. One end of spindle 64 is connected to bearing 65. Bearing 65 is fixedly mounted on bracket 63. The other end of spindle 64 is provided with a conically shaped gear-wheel 66. Axially alignable with gear-wheel 66 is a conically shaped counter gear-wheel 67. Gear-wheel 67 is mounted on shaft 68 of motor 69. Motor 69 is mounted on movable platform 70. Movable platform 70 is movably mounted on platform 71. Platform 71 is provided with an electromagnet 72 and a spring 73. Platform 70 is in contact both with electromagnet 72 and with spring 73. Platform 71 is mounted on disk 74. Disk 74 is mounted on shaft 75 of motor 76. Motor 76 is fixedly mounted relative to housing 20 as has been schematically shown in Fig. 6 through bracket 77. Motors 69 and 76 are electronically controlled by electronic control device 12 as shown by connections 78, 79 and 80. In order to move tube 39 either to the left or to the right in Fig. 6 motor 76 is controlled to rotate shaft 75 and thereby platform 71 such that counter gear-wheel 67 is opposite gear-wheel 66. Subsequently electromagnet 72 is energized thereby moving platform 70 with motor 69 to the right in Fig. 6. Thereby counter gear-wheel 67 meshes with gear-wheel 66. Then motor 69 is energized to rotate shaft 68, counter gear-wheel 67 a, gear-wheel 66 and spindle 64. Depending on the energization of motor 69 spindle 64 rotates in one direction or the other direction. Consequently element 61 and tube 39 move either to the left or to the right as desired. Fig. 7 shows a second exemplary embodiment of a means for retracting tube 39. As in Fig. 6 an element 61 is fixedly connected to tube 39. Element 61 is slideably arranged over a bar 62. In parallel to tube 39 bar 62 is fixedly mounted to housing 20 as schematically illustrated by bracket 63. A shaft 81 of a motor 82 is mounted fixedly relative to the housing 20 as indicated by brackets 83 and 84. Mounted on shaft 81 for rotation therewith are disks 85 and 86. Mounted between disks 85 and 86 and in parallel therewith is a spindle 87. Disk 86 is provided with a bearing for spindle 87 whereas disk 85 is provided with an appropriate opening therein such that spindle 87 may be connected to a motor 88 for rotation upon energization of motor 88. Mounted on spindle 88 is an electromagnet 89 with a movable core 90. The core 90 is driveable between an OUT and an IN position upon appropriate energization of electromagnet 89. Electromagnet 89 is provided with an element 91 that fits about shaft 81 in order to prevent electromagnet 89 from rotating about spindle 87 upon energization of motor 88. Motors 82 and 88 and electromagnet 89 are electronically controlled by electronic control 12. In order to move tube 39 either to the left or to the right in Fig. 7 motor 82 it controlled to rotate shaft 81 and disks 85 and 86 with motor 88 and spindle 87 and electromagnet 89 in an appropriate position. In the IN position of core 90 electromagnet 89 may move freely relative to element 61. In the OUT position of core 90 that core 90 engages element 61 when electromagnet 89 is moved in the direction of element 61. During rotation of shaft 81 by motor 82 electromagnet 89 is controlled by electronic control device 12 such that core 90 is in the IN position. After motor 82 has rotated shaft 81 such that the desired tube 39 with its element 61 may be engaged by core 90 motor 82 is de-energized and motor 88 is energized (if necessary) to rotate spindle 87 to move electromagnet 89 to the appropriate side of element 61. When tube 39 is to be moved to the right the appropriate side of element 61 is the left side and vice versa. Next electromagnet 89 is energized whereby core 90 is moved to the OUT position and subsequently motor 88 is energized to move electromagnet 89 into engagement with element 61. This situation is shown in phantom in Fig. 7. Upon continuation of the energization of motor 88 electromagnet 89 moves on and core 90 pushes against element 61. Element 61 and tube 39 are hereby moved in the same direction and over the same distance as electromagnet 89. After tube 39 has reached a desired new position electromagnet 89 is de-energized and core 90 is retracted thereby in the IN position and out of reach of element 61. Shaft 81 may now be rotated to a new position by motor 82 such that in that new position another tube 39 may be moved. Fig. 8 shows a quite simple third embodiment of means for moving tube 39. As in Figs. 6 and 7 tube 39 is provided with an element 61. A hydraulic or pneumatic cylinder 91 is mounted near element 61 on a bracket 63 which bracket is fixedly mounted relative to housing 20. Cylinder 91 has a piston 92 that may move leftward in Fig. 8. Cylinder 91 is electrically controllable by electronic control device 12 through cable 93. Cylinder 91 may be a one way or a two way device. In case it is a one way device piston 92 is kept in an OUT position for as long as cylinder 91 is energized. After de-energization of cylinder 91 piston 92 returns to an IN position. In case it is a two way device upon a first energization the piston 92 moves to an OUT (or IN) position and remains there also after de-energization. Only upon a second energization the piston moves to the IN (or OUT) position again. In case of a two way device piston 92 may be connected to element 61 as shown in phantom in Fig. 8. The number of cylinders 91 may be the same as the number of possible tubes 39. Of course it is also possible to mount a single cylinder 91 on a rotatable disk such as used in the devices shown in Figs. 6 and 7. Fig. 9 shows another embodiment of a device according to the invention. For clarity a housing has not been shown. The device 100 comprises a pushing drive module 101, two supply containers 102a for seeds and 102b for spacers respectively and a seed-spacer train assembly module 103. A flexible tube 104 is connected between the seed-spacer train assembly module 103 and an implant needle 105. A connector 106 such as a Luer connector connects tube 104 to needle 105. A plate 107 supports various elements of the device. A top view of the device is shown in Fig.10. Fig. 10 further shows a motor 108a for driving the pushing wire, a motor 108b for driving the seed and the spacer storage containers102a and 102b and a motor 108c for retracting the tube 104 and associated needle 105. Motors 108a, 108b and 108c are controlled by electronic control device 12. Further sub-modules are shown in Fig. 11. The two supply containers 102a and 102b and the pushing module 101 are clamped together to form a single module for assembly to the plate 107. Assembly module 103 comprises a detachable part 103a and a fixed (to plate 107) part 103b. Figs. 12 through 15 show in more detail the construction of the supply containers 102a and 102b. Each of the supply containers 102a and 102b comprises a back plate 108 and 109 respectively and a front plate 110 and 111 respectively. Front and back plates are held together at a specified distance by means of eight bushings six of which are shown as 112a ... 112f. Circular arrays of openings 113 are provided in each front and back plate. In the center of each circular array of openings 113 a larger opening 114 is present. Between each front and back plate a disk 115 is mounted. Each disk 115 has a center opening through which it fits over a snap-fit coupling 116. Each disk 115 is provided with teeth 123 so that it may be driven to rotate about snap-fit coupling 116. The diameters of the openings 114 and the outer dimensions of the snap-fit couplings 116 are such that the couplings 116 fit snugly but are freely rotatable in the openings 114. Each of the front and back plates is further provided with a set of openings 117 and 118 at a slightly larger radius than the openings 113. As shown in Fig. 14 each disk 115 is provided with a set of two balls 119 and 120 and a spring 121. The sets of balls 119, 120 and springs 121 are at a radius that is equal to the radius of the openings 113. Thereby the disks 115 may be rotationally fixed in position upon ball 120 coinciding with an opening 113. Each of the disks 115 with a series of bores 122 at the same radius as openings 117 and 118. The angular distance between subsequent bores 122 in disks 115 is equal to the angular distances between subsequent openings 113 in the front and the back plates 108, ..., 111. Each bore 122 may house one seed or spacer. As shown more clearly in Figs. 16 and 17 each back plate 108 and 109 respectively is provided with an opening 124 and each front plate 110 and 111 respectively is provided with a cam 125. By bringing supply containers 102a and 102b together in the way shown in Figs. 16 and 17 cam 125 of supply container 102a on front plate 110 fits into opening 124 in back plate 109 of supply container 102b. At the same time snap-fit coupling 116 of supply container 102a snap-fits into snap-fit coupling 116 of supply container 102b. Thereby both supply containers 102a and 102b form a single supply container module. Cam 125 and snap-fit coupling 116 of front plate 111 furthermore fit into openings 126 and 127 respectively of support plate 128 of pushing drive 101. As shown in Figs. 16-20 pushing drive 101 comprises a support plate 128, a fixing plate 129, a multi-diameter shaft 130 with a top 131, a pushing wire 132 and a wire storage wheel 133. The support plate 128 is provided with support notches 134 and 135 and a central opening 136. Support plate 128 further is provided with a straight groove 138. The height and width of groove 138 are essentially the same as the diameter of pushing wire 132. Multi-diameter shaft 130 comprises a top 131 of a diameter at most as large as the diameter of opening 136 in support plate 128. Top 131 is followed by a first part of a first diameter that is smaller than the diameter of the top 131, by a second part of a diameter that is substantially equal to the diameter of the opening 136, by a third part of a diameter that is larger than the diameter of the opening 136 and a fourth part with a still larger diameter. Wire storage wheel 133 comprises a groove 137. The width of the groove 137 is equal to the diameter of the pushing wire 132. The depth of the groove 137 is equal to several diameters of the pushing wire 132. The radius of the groove 137 is equal to the distance from the center of the opening 136 to the groove 138. One end of the pushing wire is fixed in the groove 137. The pushing wire 132 is contained in the groove 137 except for its other end. The other end of wire 132 runs from groove 137 into groove 138. Wheel 133 is provided with two, in this exemplary embodiment diametrically opposed, notches, one of which is visible as 139. As shown in Fig. 11 a driveable wheel 140 is provided with two cams 141 and 142. When wheel 133 is placed against wheel 140 the cams 141 and 142 fit in the notches 139 in the wheel 133. As shown in Fig. 10 wheel 140 is driveable by motor 108a. Pushing drive module 101 is assembled from the various parts as shown in Fig. 18. After the pushing drive module has been assembled and the supply containers 102a and 102b have been assembled all three are assembled together to provide a module as shown in Fig. 11. After assembly of the module of the pushing drive module 101 and the supply containers 102a and 102b that module is mounted such that the notches 134 and 135 fit in corresponding notches in pins 143 and 144 (Fig. 11). A screw in pin 145 fixes support plate 128 in position. In positioning the module care should be taken that the cams 141 and 142 fit in the notches 139. Upon placement of the module also the teeth 123 and 123a of wheels 115 and 115a respectively mesh with teeth on a shaft (not shown) of motor 108b. Groove 138 now is aligned with openings 118 and 117 and corresponding openings in supply container 102b. A relevant detail of assembly module 103 is shown in Fig. 21. A platform 146 is fixedly positioned in a groove 151 is part 103b (Fig. 11). On platform 146 a number of opto-couplers 147a,..., 147e are mounted, in the exemplary embodiment shown in Fig. 21 the number is five. The number, however, may be more or less. Opto-couplers 147 are connected to electronic control device 12. Also shown in Fig. 21 is tube 148. Tube 148 is part of detachable part 103a but has been shown here for clarity. Tube 148 is provided with a number of opposing openings 149a,..., 149e. Upon insertion of detachable part 103a in the assembly module 103 the openings 149a,..., 149e are in the lines of sight of the opto-couplers 147a,..., 147e as shown more clearly in Fig. 21A. Also then the proximal end of tube 148 is in longitudinal alignment with openings 118 and 118a in supply container 102a. Fig. 22 shows in more detail how tube 148 forms part of detachable part 103a. Detachable part 103a is an elongate element with a dorsal fin 150. Detachable part 103a fits into longitudinal groove 151 in part 103b. Upon insertion of part 103a in groove 151 tube 148 is positioned as shown in Fig. 21. Tube 104 is provided with a dumb-bell like element 156 that is attached to it in a non-sliding way, e.g. by gluing. At its distal end tube 104 is provided with a connector 106a. Dumb-bell like element 156 snaps in a notch 152 in pin 153. Pin 153 is mounted at a distal end of a toothed bar 154. The teeth of toothed bar 154 mesh with a gear-wheel 155 mounted on a shaft of motor 108c. Toothed bar 154 slides in housing 103c. Tube 104 has a length of about 30 centimeter and is made of a nickel-titanium alloy. Thereby tube 104 is very flexible without risk of breaking or kinking. It may be connected with various implant needles 105 without having to displace device 100. At its proximal end tube 104 fits slidingly over the distal end of tube 148. Tube 148 is slid into tube 104 upon insertion of detachable part 103a into groove 151. Upon operation of the device 100 first a seed supply container 102a and a spacer supply container 102b are filled with seeds and spacers respectively and coupled together. Subsequently both are coupled to pushing module 101. Next the module thus assembled is mounted into position on pins 143 and 144 and fixed in position by means of the screw in pin 145. Further detachable part 103a is inserted into groove 151 under concurrent fitting tube 104 over tube 148. Toothed bar 154 is in its OUT position, i.e. a position as shown in Fig. 23B. From that position toothed bar 154 may be moved inwardly only to its IN position, in which IN position it may not be moved to the left in Fig. 23B anymore. Under control of electronic control device 12 motor 108a is activated to rotate wheel 140 such that wire 132 is driven out of module 101. Due to the alignment of groove 138 with openings 118 and 118a the wire 132 pushes the spacer and the seed present in the corresponding openings 122 into the tube 148. It may be noted that a spacer seed set may also consist of only a spacer or only a seed depending on the required radiation distribution as determined by the therapy planning module 12a. Opto-couplers 147 detect the passage of the seed-spacer pair until it reaches the distal opto-coupler 147a. Then the wire 132 is retracted into groove 138. Next the seed and spacer supply containers 102a and 102b are rotated one step by means of motor 108b. Then again motor 108a is activated to move wire 132 to push a second seed-spacer pair into tube 148. Presence of the second seed-spacer pair is detected by opto-coupler 147b. Again the wire 132 is retracted and a third seed-spacer pair may be inserted into tube 148. This continues until all seed-spacer pairs are present in tube 148 thereby making up a seed-spacer train. Tube 104 now is or already was connected to the needle for which the seed-spacer train was intended. After the last seed-spacer pair had been introduced into tube 148 wire 132 had not been retracted anymore. Motor 108a now is controlled to move wire 132 further out. Thereby the seed-spacer train that had been built up in tube 148 is moved through tube 148 into tube 104 and further into needle 105 until it reaches the distal end of needle 105. As described before needle 105 is an open needle with a wax plug at its distal end. Since all elements have predetermined dimensions it is easy to control motors 108a, 108b and 108c such that the seed-spacer train stops just in front of the wax plug. The motors 108a, 108b and 108c may thereto be provided with known coding disks or may be stepper motors. After the seed-spacer train has been delivered into the distal end of the needle 105 just in front of the wax plug wire 132 is kept in that position. Next motor 108c is energized to move toothed bar 154 to the right in Fig. 23A. Thereby pin 153 through dumb-bell like element 156reracts tube 104 and needle 105. Tube 104 then slides over tube 148. Alternatively since tube 104 is made of such a flexible material a slack may form between pin 153 sand tube 148 thereby doing away with the requirement that tube 104 slide over tube 148. Next tube 104 is coupled to a next needle and the operation described hereinabove is repeated. That continues until all seed-spacer trains have been delivered into the prostate gland 111. Then tube 104 is decoupled from the last used needle. Subsequently all needles are removed from the body for sterilization or disposal. In the device 100 blood contamination may have taken place of tube 104, tube 148, supply containers 102a and 102b and pushing drive module 101. All those elements are taken out of device 100 for sterilization or disposal. Depending on what in a certain situation is desired by a hospital those elements may be made of sterilizable material such as stainless steel or of disposable material such as plastics. Present day plastics have such good form stability that it is possible to manufacture the disposable elements with a sufficient degree of accuracy for the present application. Like with the embodiment shown in Fig. 2 it is possible with the embodiment of Fig. 9 to split up the device 100 in two modules, one a seed loading module for filling a multichannel holder 31 with seed-spacer trains in its channels 33 and a second one a seed implanting module for implanting the seed-spacer trains present in a multichannel holder in an animal body. Fig. 25 shows such a device with a multichannel holder 157. Multichannel holder 157 is in principle identical to multichannel holder 31 as described hereinbefore in relation to Fig. 2 and now is placed at and connected to the exit of tube 148. Means are provided for rotating multichannel holder 157. Multichannel holder 157 may therefore be provided with a ring of teeth 158 which may mesh upon placement in the device with the teeth of a gear-wheel on a shaft of a motor 159 (Fig. 26). In order to fill the channels in the multichannel holder 157 the operation of device 100 as hereinbefore described is applicable until the point where the seed-spacer train that has been assembled in tube 148 is pushed into the tube 104. Instead of pushing the seed-spacer train in tube 104 the seed-spacer train is pushed in the channel of multichannel holder 157 that is longitudinally aligned with tube 148. Thereafter motor 159 is energized to rotate multichannel holder 157 such the next available channel is longitudinally aligned with tube 148. Thereafter the next seed-spacer train is assembled in tube 148 and subsequently pushed into the channel in multichannel holder 157. This operation continues until all appropriate channels in multichannel holder 157 have been filled with the appropriate seed-spacer trains. Fig. 27 shows the device when using the filled multichannel holder 157 for depositing the seed-spacer trains in the body. Instead of the supply containers 102a and 102b multichannel holder 157 is fixed to pushing drive module 101 in essentially the same way as the supply containers 102a and 102b were fixed to that module. Teeth 158 mesh with the teeth of a gear-wheel on a shaft of motor 108a. Between the output side of multichannel holder 157 a fixedly positioned tube 160 is present. Tube 160 fits in tube 104 such that tube 104 is slideable over tube 160. Tube 160 is longitudinally aligned with groove 138 and with the channel in multichannel holder 157 between groove 138 and tube 160. Operation of the device shown in Fig. 27 for depositing the seed-spacer trains in the body is as follows. Tube 104 is connected to a first needle 105. Multichannel holder 157 and pushing drive 101 are installed. Multichannel holder 157 is rotated such that the appropriate channel with the seed-spacer train for the first needle is longitudinally aligned with tube 160 and groove 138. Then motor 108a and subsequently motor 108c are energized to push the seed-spacer train into the first needle and retract the first needle. After all seed-spacer trains have been delivered in the body all needles are removed from the body, tubes 104 and 160, multichannel holder 157 and pushing drive 101 are removed for sterilization or disposal. Various embodiments of the invention have been described hereinbefore in which the retracting means for the implant needles were operated by motors under electronic control. Without departing from the scope of the invention it is also possible to operate the retracting means manually, i.e. by moving the elements 60 and 61 respectively by hand. It should be noted that according to the abovementioned, various modifications may be obvious to a person skilled in the art. Such modifications are deemed to be within the scope of the invention.

Claims: A device for implanting radioactive seeds in a desired pattern in an animal body through a number of needles (10) implanted in said animal body, said number being one or more, said device comprising a seed implanting module at least consisting of: electronic control (12) means provided with said desired pattern; loading means (8) connected to said control means for arranging a number of trains of said radioactive seeds in accordance with said desired pattern in an equal number of channels (33) within said loading means in response to said control means; drive means (27) connected to said control means for extending a wire to push said trains of radioactive seeds from said channels through a number of tubes (38), said number being one or more, each said tube coupled at a first end to one of said channels and coupled at a second end to one of said needles in response to said control means. Device in accordance with claim 1, further comprising retracting means connected to said implant needles for retracting each of said implant needles from said animal body while said pushing wire is in an extended position to thereby implant said radioactive seeds. Device in accordance with claim 1 or 2, wherein said loading means further includes a multichannel holder connected to said control means and wherein said control means controls said loading means to arrange a train of seeds in a separate channel in said multichannel holder for each of said implant needles. Device in accordance with claim 2, wherein said retracting means are electronically controllable and are connected to and operatable in response to signals from said control means. Device in accordance with claim 4, wherein said retracting means are electrically operatable. Device in accordance with claim 4, wherein said retracting means are hydraulically operatable. Device in accordance with claim 4, wherein said retracting means are pneumatically operatable. Device in accordance with claim 1, wherein said tube(s) comprise a first part and a second part, which first and second parts overlap, said first part being connected to said loading means and said second part being slidable relative to said first part and coupled to said implant needles. Device in accordance with claim 8, wherein said second part is connected to said retracting means. Device in accordance with claim 1, wherein said tube(s) coupled to said implant needles is made of a nickel titanium alloy. Device in accordance with claim 8, wherein said second part is made of a nickel titanium alloy. Device in accordance with claim 1, wherein said loading means further includes a supply container having a reservoir for radioactive seeds. Device in accordance with claim 12, wherein said supply container has a second reservoir for spacers. Device in accordance with claim 3, wherein said loading means further comprises a rotatable plate having plural openings there through mounted between said multichannel holder and said tube and connected to said control means, and wherein said control means rotates said plate to align said openings with the channels in the multichannel holder when said drive means are operating and rotates said plate out of alignment to block said channels when said loading means is operating to arrange said seed trains in said channels. Device in accordance with claim 12, wherein said supply container further includes first push means for pushing a radioactive seed from said reservoir into said channel in response to a signal from said control means and second push means for pushing a spacer from said second reservoir into said channel in response to a signal from said control means. Device in accordance with claim 12, wherein said supply container is removable. Device in accordance with claim 1, wherein said drive means is removable. Device in accordance with claim 1, wherein said tube is removable. Device in accordance with claim 3, wherein said multichannel holder is removable. Device in accordance with claim 19 further comprising receiving means for receiving a number of trains of radioactive seeds in said number of channels in said removable multichannel holder. Device in accordance with any one of the preceding claims, further comprising therapy planning means connected to said control means for providing said control means with signals representing said desired pattern of seeds in a train for each of said needles, and wherein said control means controls said loading means in response to said signals from said therapy planning means. A device in accordance with claim 1, wherein blood contaminatable parts are removable. A device in accordance with claim 22, wherein said removable and blood contaminatable parts are disposable. A device in accordance with claim 22, wherein said removable and blood contaminatable parts are sterilizable. A device in accordance with any one of the preceding claims, wherein said drive means comprises first and second elements rotatable relative to each other about a common axis, said first and second elements having contact surfaces, said contact surfaces in each rotational position of said first and second elements relative to each other being in contact with each other in a contact area along a common contact plane, a storage space for said wire going around said axis in said first element, said storage space along a length of it being open to said contact surface of said first element, said contact plane extending from a distance from said axis smaller than a smallest distance of said storage space from said axis to a distance from said axis greater than a largest distance of said storage space from said axis, said second element comprising a channel for said wire, said channel being open to said contact plane at a first position opposite said storage space and extending to a second position at a surface of said second element outside said contact area of said common contact plane. A device in accordance with to claim 25, wherein said storage space comprises a groove in said first element. A device in accordance with to claim 26, wherein said groove is circular. A device in accordance with to claim 26 or 27, wherein a width of said groove is substantially equal to a width of said wire. A device in accordance with to claim 25, wherein said contact plane is a flat plane. A device in accordance with to claim 25, further comprising a common shaft for the first and second elements, wherein an axis of said shaft coincides with said axis of said first and second elements. A device in accordance with to claim 30, wherein said first element is freely rotatable about said shaft and wherein means are present for rotating said first element about said shaft. A device in accordance with to claim 25, wherein said drive means are disposable. A method for loading radioactive seeds in a number of implant needles disclaiming methods for treatment of the human or animal body by surgery or therapy, said number being one or more, said method comprising: determining a desired pattern of seeds and inputting said desired pattern into an electronic control device; arranging at least one train of seeds in accordance with said desired pattern for at least one of said implant needles in response to signals from said control device; extending a drive wire to push said at least one train of seeds into a corresponding one of said implant needles in accordance with said desired pattern in response to signals from said control device and retracting the drive wire.

Inventors: KINDLEIN JOHANN, LOEFFLER EDGAR GERMAN, VISSCHER ARIE LUITE, KINDLEIN, JOHANN, LOEFFLER, EDGAR GERMAN, VISSCHER, ARIE LUITE, Löffler, Edgar German
Applicants: NUCLETRON BV, NUCLETRON B.V.
Application year: 2000
Main classification: A61N5
IPC codes: A61M36, A61N5