Abstract:
A device for implanting radioactive seeds and non-radioactive spacers in a desired configuration in an animal body for effecting radiation therapy. An elongated hollow needle is inserted in the body. A pushing element implants the row of seeds and spacers though the hollow needle towards the desired location. A tube shaped element receives the row of seeds and spacers. A lube shaped sleeve having open ends is used to insert the tube shaped element through the needle and toward the location. The pushing elements pushes the row of seeds and spacers into the desired location while still being carried in the tube shaped element.

Description:
This nonprovisional application claims priority under 35 U.S.C. § 119(a) on patent application Ser. No(s). 02079170.3 filed in EUROPE on Oct. 7, 2002, which is (are) herein incorporated by reference. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The invention relates to a device for implanting at least one row of X radioactive seeds and Y non-radioactive spacers with X∈[1, 2, . . . ] and Y∈[0, 1, . . . ] in a desired configuration to a desired location in an animal body for effecting radiation therapy of cancerous tissue in said body, said device comprising: at least one elongated hollow needle with an open distal end to be inserted towards said desired location in the body and with a proximal end to be connected to a seed loading apparatus; and at least one pushing element for implanting during retraction of the elongated hollow needle said row of radioactive seeds and non-radioactive spacers from said seed loading apparatus through said hollow needle towards said location. 
   The invention moreover relates to a seed loading apparatus provided with an implanting device according to the invention as well as to a row of X radioactive seeds and Y non-radioactive spacers with X∈ [1, 2, . . . ] and Y∈[0, 1, . . . ] in a desired configuration, wherein said seeds and spacers are accommodated in a tube-shaped element according to the invention. 
   2. Description of the Background 
   In the European patent application no. 1070519 in the name of the applicant of this application an apparatus for implanting radioactive seeds in e.g. the male prostate gland is disclosed. Under ultrasound guidance using an ultrasound probe and using a first template implant needles, hereinafter needles, are placed in the prostate gland. Under fluoroscopy the positions of the needles are checked and for every individual needle the length and configuration of the row or train of seeds/spacers is determined using a radiation therapy treatment module. 
   In order to finalize the implant procedure each row of seeds/spaces is urged through it&#39;s corresponding needle towards the open distal end of the hollow needle in the prostate gland using a pushing element. Subsequently the pushing element is fixed and the hollow needle is retracted over a distance equal or slightly greater than the length of the row of seeds/spacers, thereby introducing the row of seeds/spacers at it&#39;s intended postion within the prostate gland. 
   Next the pushing element is withdrawn into the seed loading unit for pushing a next seed-spacer row through another needle into the prostate gland. The delivery of subsequent seed/spacers rows in the prostate gland continues until each needle has been retracted and a number of seed-spacer rows equal to the number of needles has been positioned at different locations within in the prostate gland. 
   The known apparatus is then disconnected and the needles are retracted from the patient completely. A final control/check of the geometry/presence of the implanted seeds in the prostate gland is performed under fluoroscopy or another imaging technique and after removal of the ultrasound probe the patient is hospitalized for recovery. 
   Examples of configurations of a row of radioactive seeds and non-radioactive spacers are for example disclosed in the International Patent Application Nos. WO02/20089, WO00/09211, WO99/59675 and in the U.S. Pat. No. 4,815,449. 
   Each row of radioactive seeds and non-radioactive spacers as disclosed in the above prior art patent publications has the disadvantage that after insertion into the body or near to the tissue to be irradiated the inserted seeds and spacers are only accommodated/enveloped by tissue of the body. 
   Furthermore all rows of seeds/spacers as disclosed in the cited prior art patent publications can only be configured in a seeds/spacer configuration consisting of a repeated configuration “seed, spacer, seed, spacer, . . . ”. This gives less flexibility in configuring the treatment plan and seed/spacer trains in another configuration/sequence. 
   That may have a consequence that upon movements of the body in which the row of radioactive seeds and non-radioactive spacers has been inserted the radioactive seeds and non-radioactive spacers may move through the body/the tissue to be irradiated and as a consequence of these movements undesired irradiation of other tissue will occur. 
   This will be disadvantageous for the therapeutic treatment since the distribution of the radioactive seeds and non-radioactive spacers in each row has been calculated with great accuracy in order to reach an optimal result in respect of the irradiation of the tissue to be treated. In general not one but a number or even a great number of rows of radioactive seeds and non-radioactive spacers, each arranged with a predetermined pitch, is inserted in order to irradiate the tissue, often cancerous tissue and their exact position within the tissue has been calculated using a specific radiation therapy treatment module in order to spare/avoid undesired radiation of fragile tissue or organs, e.g. the urethra, bladder or rectum during the treatment of the prostate gland. 
   There is therefore a need for rows of radioactive seeds and non-radioactive spacers for brachytherapeutic treatment of tissue with radioactive radiation in which mutual displacement of the seeds/spacers after insertion of the row into the body is avoided due to e.g. movements of the patient or other disturbances within the body like swellings, blood circulation etc. 
   SUMMARY OF THE INVENTION 
   The present invention aims to provide a tool and method for implanting rows of radioactive seeds and spacers without having the above described prior art drawbacks and without modifying the existing implantation techniques. 
   According to the inventing the device further comprises at least one tube-shaped element with at least one open end to be inserted through said hollow needle towards said desired location; and at least one tube-shaped sleeve member with an open distal and open proximal end for inserting said tube-shaped element through said hollow needle towards said desired location, wherein said tube-shaped element serves to accommodate said row of radioactive seeds and non-radioactive spacers. 
   With the use of a tube-shaped element which serves to accommodate said row of radioactive seeds and non-radioactive spacers it is avoided that the row of seeds/spacers displaces within the organ to be treated after insertion due to e.g. movements of the patient or other disturbances within the body like swellings, blood circulation etc. The proposed radiation therapy treatment is not adversely affected and undesired irradiation of other tissue, for example fragile organs like the urethra, the bladder or the rectum is avoided. 
   Preferably said tube-shaped element is inserted through said hollow needle prior to the insertion of the row of radioactive seeds and non-radioactive spacers. 
   More in particular said pushing element is constructed as a rigid pushing rod, whereas in another embodiment the pushing element is constructed as a drive wire of the seed loading apparatus. 
   In order to avoid the insertion of said tube-shaped sleeve member past the proximal end within the elongated hollow needle said tube-shaped sleeve member is provided at his proximal end with a stopper element, which stopper element in a specific embodiment is constructed as a disk shaped end plate. 
   For a proper functioning of the implanting device according to the invention are the outer dimensions of the tube-shaped sleeve member and the tube-shaped element equal or slightly smaller than the inner dimensions of said hollow needle and furthermore are the inner dimensions of the tube-shaped sleeve and the tube-shaped element equal or slightly larger than the outer dimensions of said radioactive seed and non-radioactive spacer. 
   Furthermore, for a proper functioning of the implanting device when implanting a row of seeds/spacers into the animal body the dimensions of the several parts of the implanting device conforms the equation
 
 l ≧( X+Y ) s  and  S ≦( L−l ),
 
in which
 
   l is the length of the tube-shaped element; 
   s is the length of one individual seed/spacer; 
   L is the length of the hollow needle; 
   S is the length of the tube-shaped sleeve member. 
   This makes it possible to use tube-shaped elements specifically designed for a row of seeds/spacers of a specific length, and thus avoiding the above-described problems of the prior art rows, namely the displacement of the seeds and spacers. 
   According to a specific embodiment said tube-shaped element is made of a bio-absorbable material, and more in particular at least the proximal end of said tube-shaped element is collapsible. This last feature creates a tube-shaped element completely enclosing the row of seeds/spacers inside the body after retraction of the hollow needle and further avoids a possible displacement of the seeds/spacers in the organ to be irradiated. 
   Moreover the tube-shaped element may have two open ends or one closed end, more in particular a closed distal end. 
   In another embodiment the tube-shaped element has a oval-shaped cross-section prior to the insertion through the hollow needle, and wherein the tube-shaped element has a circular cross section when inserted in the hollow needle. 
   However also tube-shaped elements having a circular cross section are very suitable for use with the implanting device according to the invention. 
   More especially the tube-shaped element according to the invention is made of a flexible or elastic material capable for exerting an inwardly directed force on the row of radioactive seeds and non-radioactive spacers. 
   These two features (oval shape and flexible/elastic) creates an improved fixation of the row of seeds/spacers within the tube-shaped element and the animal body further limiting the risk of displacement of the seeds/spacers through the animal body. 
   This fixation phenomenon can be further improved, as according to the invention at least the open proximal end of said tube-shaped element is collapsable. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will now be described in more detail with reference to the accompanying drawings, which show: 
       FIG. 1  a schematic view of an apparatus for implanting radioactive seeds using a hollow needle according to the state of the art; 
       FIGS. 2   a - 2   b  a first embodiment of an implanting device according to the invention; 
       FIGS. 3   a - 3   f  subsequent stages showing the method for implanting a row of seeds/spacers using the implanting device according to the invention; 
       FIGS. 4   a - 4   c  another embodiment of a part of the implanting device according to the invention. 
   

   DETAILED DESCRIPTION OF THE 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 manually or with the use of a seed loading apparatus 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  4   a  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  4   a . 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 the seed loading unit  8  is connectable to the table  4 . In a second embodiment the seed loading unit  8  is a stand alone unit. 
   A well-known therapy planning module  12   a  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  12   a  usually comprises a computer programmed with a therapy planning program. One such a therapy planning program is marketed under the trademarks PLATO™, SPOT™ and SPOT PRO™ by Nucletron B.V. of the Netherlands. Other such programs are also known. The therapy planning module  12   a  is connected to the seed loading unit  8  through a control device  12  for controlling the number of seeds for each needle. The 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  12   a  or may be embodied in the software of the therapy planning module  12   a  or of the seed loading unit  8 . 
   The device shown in  FIG. 1  operates as follows. A patient  1  is under spinal or general anesthesia and lying on the operating table  2  in lithotomy position. The transrectal 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  12   a  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 radioactive seeds are spaced from each other by non-radioactive 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 row 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  12   a . The seed loading unit  8  is controlled by the control device  12  to make up a seed-spacer train for each needle  10 . 
   The creation of a specific seed-spacer train will not be described herein, but is for example disclosed in the European patent application no. 1 070 519 in the name of the applicant of this application and herewith incorporated by reference. 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  12   b  to the control device  12  the pushing drive pushes with a pushing element, e.g. a pushing wire the seed-spacer train just until it reaches the distal end of the specific hollow 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. 
   As stated above, each row of radioactive seeds and non-radioactive spacers as disclosed in the above prior art patent publications has the disadvantage that after insertion into the body or near to the tissue to be irradiated the inserted seeds and spacers are only accommodated/enveloped by tissue of the body. 
   Furthermore all rows of seeds/spacers as disclosed in the cited prior art patent publications can only be configured in a seeds/spacer configuration consisting of a repeated configuration “seed, spacer, seed, spacer, . . . ”. This gives less flexibility in configuring the treatment plan and seed/spacer trains in another configuration/sequence. 
   Therefore, movements of the patient or blood circulation and swelling may result in a displacement of the radioactive seeds and non-radioactive spacers through the body thus adversely affecting the intended, conformal therapeutic radiation treatment as preplanned by the radiation therapy treatment module. 
   The displacement of the radioactive seeds and non-radioactive spacers within the body may result in an undesired irradiation of other tissue or fragile organs, whereas the original, intended treatment situation will no longer be met. 
   In  FIG. 2   a  and  FIG. 2   b  a first embodiment of an implanting device for a row of radioactive seeds and non-radioactive spacers is disclosed, which obviates the known prior art drawbacks without the necessity of modifying the existing implantation techniques. 
   Similar parts in the following Figures are denoted by the same reference numerals. 
   The implanting device according to the invention can be used as a replacement for the implant needle  10  as described in relation to  FIG. 1 . 
   The device  10  according of the invention comprises an elongated hollow needle  10  having a open distal end  15  to be inserted into the body near a desired location where irradiation of body tissue has to take place, as well as a proximal end  14 . The open distal end  15  can be constructed as a sharp stylet, for an easy and correct insertion into the body. The implanting device further comprises a tube-shaped element  20  having a proximal end  21  and a distal end  22 . 
   Said tube-shaped element  20  has at least one open end. In the embodiment shown in  FIG. 2   a  the tube-shaped element  20  has a closed distal end  22  and an open proximal end  21 , however another embodiments of the tube-shaped element  22  may consist of two open proximal and distal ends  21  respectively  22 . 
   The device furthermore comprises a hollow tube-shaped sleeve member  30  with an open distal end  32  and an open proximal end  31 . 
   The outer dimensions of both the tube-shaped element  20  and the tube-shaped sleeve member  30  are equal or slightly smaller than the inner dimensions of the elongated hollow needle  10 , such that both the tube-shaped element  20  as well as the tube-shaped sleeve member  30  can be inserted in a slidable manner through the elongated hollow needle  10 . In fact, the tube-shaped sleeve member  30  serves to insert the tube-shaped element  20  from the proximal end  14  through the hollow needle  10  towards the open distal end  15  of the hollow needle  10 . 
   The implanting device  10  furthermore comprises a pushing rod  40  having at least the same length as the elongated hollow needle  10 , which pushing rod is preferably made of a rigid material. The outer dimensions of the pushing rod  40  are equal or slightly smaller than the inner dimensions of the tube-shaped element  20  and tube-shaped sleeve member  30  respectively. Thus the pushing rod can be slidable inserted through the tube-shaped element and tube-shaped sleeve member. 
     FIG. 2   b  discloses the implanting device  10  with all separate parts mounted within the elongated hollow needle  10 . The tube-shaped sleeve member  30  may be provided at its proximal end  31  with a stopper element  33 , which stopper element  33  in this embodiment is constructed as a disk-shaped plate. The stopper element prevents the complete insertion of the sleeve member  30  inside said hollow needle  10 , as the disk-shaped plate  33  abuts against the proximal end  14  of the elongated hollow needle  10 . 
     FIGS. 3   a - 3   f  show the subsequent stages for implanting a row of radioactive seeds and non-radioactive spacers within the animal body towards a desired location and also elucidate the method for inserting such a row within an animal body. 
   In a first principle of the method for inserting a row of radioactive seeds and non-radioactive spacers within an animal body for radiation treatment of cancerous tissue, the assembly of the different parts of the implanting device  10  according to the invention as shown in  FIG. 2   b  is inserted entirely into the animal body (here the male prostate gland  11 ) in the direction depicted by the arrow. 
   The tube-shaped element  20  as well as the tube-shaped sleeve member  30  and the pushing rot  40  are slidable received within the hollow elongated needle  10 , which needle is inserted with its sharp open distal end  15  within the prostate gland  11 . 
   In  FIG. 3   b  the pushing rod  40  is retracted from the hollow needle  10 , whereas the proximal end  14  of the hollow needle  10  is connected to a seed loading apparatus. Such seed loading apparatus is for example described in conjunction with  FIG. 1 . 
   From the seed loading apparatus  60  a seed train consisting of radioactive seeds  80   a  and non-radioactive spacers  80   b  is inserted through the tube-shaped sleeve member  30  (and the hollow needle  10 ) towards the distal end  15  of the needle  10  (and the tube-shaped element  20 ) using a push wire  70  of the seed loading apparatus  60 . 
   In an alternative insertion principle the seed train  80   a - 80   b  can be inserted through the hollow needle  10  manually using the pushing rod  40  as shown in  FIG. 3   a  (and  FIG. 2   b ). 
   Once the seed train  80   a - 80   b  is completely pushed toward the proximal end  15  of the hollow needle  10  and within the tube-shaped element  20  the push wire  70  is fixed and the hollow needle  10  together with the tube-shaped sleeve member  30  are retracted over a distance equal or slightly greater than the length of the tube-shaped element  20 . As a result of this retraction of the hollow needle  10  and the tube-shaped sleeve member  30  the tube-shaped element  20  together with the seed train  80   a - 80   b  is introduced in the prostate gland  11 . See  FIG. 3   e.    
   Subsequently the pushing wire  70  is retracted from the hollow needle  10  within the seed loading apparatus  60  for pushing a subsequent row of radioactive seeds and non-radioactive spacers through another needle  10  implanted in the prostate gland  11 . 
   Once all rows of radioactive seeds and non-radioactive spacers are inserted into the prostate gland  11  through their corresponding implant devices  10  all hollow needles  10  including the tube-shaped sleeve members  30  are retracted from the patient. This situation is shown in  FIG. 3   e.    
   Now the row of radioactive seeds  80   a  and non-radioactive spacers  80   b  is accommodated within a tube-shaped element  20  their mutual relationship within the prostate gland  11  to be treated is not disturbed due to movements of the patient. Therefore, the risk of irradiation of fragile tissue or organs is herewith minimized or avoided. Moreover the conditions for the intended conformal radiation treatment are met and performed as preplanned. 
   Although the embodiment as disclosed in  FIGS. 3   a - 3   b  comprises one closed distal end  22  and one open proximal end  21  in another embodiment the tube-shaped element  20  may comprise two open ends  21 - 22 . 
   Preferably, the length of the tube-shaped element  20  is equal to the length of the seed train or the tube-shaped element  20  may be slightly longer than the corresponding seed train, as shown in  FIG. 3   e . Preferably radioactive seeds and non-radioactive having identical outer dimensions are used, and for each row of seeds/spacers having a specific configuration/length a tube-shaped element having a corresponding length can be used. 
   The tube-shaped element  20  can have a length slightly longer than the length of the seed/spacer train, wherein the part  23  of the proximal end  21  may have a smaller thickness than the rest of the tube-shaped element  20 . This part  23  of the tube-shaped element  20  may collapse due to the tissue surrounding the tube-shaped element  20  after retraction of the hollow needle  10 , creating a tube-shaped element  20  completely enclosing the seed train  80   a - 80   b . This further avoids any possible displacement of the radio active seeds and non-radioactive spacers within tube-shaped element  20  (and prostate gland  11 ), thus preventing any undesired irradiation of other tissue or fragile organs such as the urethra, bladder or rectum. 
   The tube-shaped element  20  can be made from a bio-absorbable material. 
   In conjunction with the  FIGS. 2   a - 2   b  and  3   a - 3   f  a tube-shaped element  20  has been described having a circular cross section of which the outer dimensions are equal or slightly smaller than the circular inner dimensions of the hollow needle  10 . 
   Another embodiment of the tube-shaped element  20  is disclosed in  FIGS. 4   a - 4   c  wherein in  FIG. 4   a  the tube-shaped element  20  is depicted in a state prior to the insertion through the hollow needle  10 . In this embodiment the tube-shaped element  20  has an oval cross section. 
   When inserted through the hollow needle  10  using the tube-shaped sleeve member  30  the oval tube-shaped element  20  will follow the circular inner dimensions of the elongated hollow needle  10  and will be urged into a circular cross section as depicted in  FIG. 4   b.    
   When the hollow needle  10  is retracted together with the tube-shaped sleeve member  30  from the prostate gland  11  leaving the tube-shaped element  20  with the seed train  80   a - 80   b  at the desired radiation location within the prostate gland  11  (like  FIG. 3   e ) the tube-shaped element  20  will return to its initial oval cross-section, as depicted in  FIG. 4   c . The oval shaped tube-shaped element  20  will exert an inwardly directed force on the radioactive seeds  80   a  and non-radioactive spacers  80   b  within the tube-shaped element  20  resulting in a fixation within the prostate gland  11 . 
   This feature further limits the risk of any displacement of the seeds/spacers due to movement of the patient or other disturbances within the body (swellings, blood circulation, etc.). This phenomenon can be supported by making the tube-shaped element of a flexible or elastic material. 
   This same feature is also applicable to a tube-shaped element  20  with circular cross-section, wherein the outer dimensions of the seeds and spacer are equal or slightly smaller than the circular inner dimension of the element  20 . The tube-shaped element  20  thereby exerts a small friction force on the row of seeds/spacers preventing them from displacements. 
   It will be clear from the above that with the implanting device according to the invention a more conformal radiation treatment can be performed without the risk of irradiating fragile organs or healthy tissue as any displacement of the seeds/spacers due to movements of the patient are herewith avoided. 
   With reference to the  FIGS. 3   a - 3   f  a method principle is disclosed, wherein the tube-shaped sleeve member  30  and the tube-shaped element  20  are mounted on the pushing rod  40 , which assembly is inserted inside the hollow needle, which needle is then inserted into the animal body towards a desired location within the prostate gland  11 . 
   With another method principle for implanting a row of radioactive seeds and non-radioactive spacers within the animal body, the hollow needle  10  is inserted into the animal body followed by the subsequent insertion of the tube-shaped element  20 , the tube-shaped sleeve member  30  and the pushing rod  40 .