fig1 and 2 show generally a first embodiment of a disposable template grid 10 according to the present invention . template grid 10 has a series of passages 12 extending from a front 14 through a back 16 . passages 12 are sized to accommodate a medical implant such as seed - containing needles and can be chamfered at front 14 and / or back 16 to facilitate insertion of the implant . passages 12 are arranged in a pattern corresponding to a software - generated pattern superimposed on images from an imaging probe . a recess 18 for providing clearance for a portion of the probe interrupts the matrix in which passages 12 are arranged . in order to help the user distinguish the passages 12 from each other , front 14 and back 16 have letters 22 identifying the various columns of passages 12 and numbers 24 identifying the various rows of passages 12 . as users have different preferences for the manner in which passages 12 are identified , the configuration of the letters 20 and numbers 22 on front 14 need not be identical to the configuration on back 16 . letters 20 and numbers 22 can be made on front 14 and back 16 by a number of methods including silk screening , molding , engraving , or chemical etching . any other method which provides a permanent placement of these indicia on the template can be used . as shown in fig3 - 6 , front 14 of template grid 10 comprises a front portion 24 and back 16 of template grid 10 comprises a rear portion 26 . front portion 24 includes front channels 28 . each of the front channels 28 has a first opening 30 on a first surface 32 connected by a front tubular member 34 to a second opening 36 on a second surface 38 . similarly , rear portion 26 includes rear channels 40 . each of the rear channels 40 has a first opening 42 on a first surface 44 connected by a rear tubular member 46 to a second opening 48 on a second surface 50 . as best seen in fig6 when front 24 and rear 26 portions are joined together , the front channels 28 align with the rear channels 40 to form passages 12 . there are a number of different ways in which front portion 24 can be attached to rear portion 26 so that front 28 and rear 40 channels proper align . for example , a shoulder 52 on second surface 38 of front portion 24 engages a groove 54 on second surface 50 of rear portion 26 to connect front 24 and rear 26 portions . alternatively , shoulder 52 can be on rear portion 26 while groove 54 is on front portion 24 . in the embodiment of fig5 and 6 , a portion of rear tubular member 46 has an enlarged diameter 56 for receiving a portion of front tubular member 34 . an adhesive can be used to secure front 24 and rear 26 portions . as previously discussed , the effectiveness of the brachytherapy is highly dependent upon accurate placement of the needles . as a result , the diameter of passages 12 and the spacings between the passages 12 have to be carefully controlled . by making template grid 10 in two halves ( i . e ., a front portion 24 and a rear portion 26 ) and then mating second surface 38 with second surface 50 , the diameter and spacing of passages 12 need only be precisely controlled for a very small distance , i . e ., near first surface 32 of front portion 24 and near first surface 44 of rear portion 26 . as this allows most of front tubular member 34 and rear tubular member 46 to be made with much larger tolerances without adversely affecting the accuracy in placement and size of passages 12 , template grid 10 can be manufactured at a cost and effort that makes disposability commercially practical . although there are a number of different materials suitable for front 24 and rear 26 portions , front 24 and rear 26 portions are preferably made of a plastic using an injection molding process . after fabrication , the disposable template grid 10 can be sterilized by steam sterilization , gas sterilization , or irradiation . presently , gamma - irradiation is the preferred method of sterilization . template grid has at least one mating element for connection to a grid supporting member . generally , at least two mating elements are used . preferably , a pair of prongs 58 operatively associated with a pair of grooves on the grid supporting member , are used for this connection . a preferred arrangement is shown , but the number and location of prongs 58 can be varied as desired to suit the configuration of the grid supporting member . fig7 - 10 show a second embodiment of a disposable template grid according to the present invention . in general , this embodiment of the disposable template grid has like or comparable structure to disposable template grid 10 . accordingly , like components are given identical references numerals and discussion of these like components is not believed necessary . the disposable template grid comprises an insert 112 and bracket 114 . insert 112 has a plurality of channels 116 arranged in a matrix and bracket 114 has similarly arranged apertures 118 . when insert 112 is installed in bracket 114 as discussed in more detail below , channels 116 and apertures 118 align . as channels 116 and apertures 118 are sized to accommodate a medical implant such as seed - containing needles , the implant can pass through bracket 114 and insert 112 . preferably , the ends of these channels can be chamfered to assist in guiding the medical implant into the channels and facilitate implant insertion . channels 116 and apertures 118 can both be chamfered , if desired , for this purpose . the conical shape of the chamfer enables the implant to be easily inserted into the channels . insert 112 is a substantially rectangular block of material that is sized to fit in bracket 114 . the rectangular structure of insert 112 is interrupted by recess 18 and cut - outs 120 . bracket 114 has a front face 122 , top 124 , and side surfaces 126 . the bottom of bracket 114 comprises two ledges 128 which extend only partially toward recess 18 and support cut - outs 120 when insert 112 is installed in bracket 114 . bracket 114 has an open back allowing insert 112 to be installed by sliding insert 112 at an angle until cut - outs 120 rest on ledges 128 . in order to further assist installation , sides 126 have an open center section so that insert 112 can be grabbed until it is correctly introduced in bracket 114 . prongs 58 extend through the top and bottom of ledges 128 of bracket 114 . as previously discussed , one end of prongs 58 engages a grid supporting member . cut - outs 120 of insert 112 each have a slot 130 for receiving the top end of prongs 58 . the engagement of slots 130 with prongs 58 ensures proper alignment of channels 116 and apertures 118 . a set screw 134 on top 124 of bracket 114 is tightened into a groove 132 on insert 112 in order to secure insert 112 to bracket 114 . although both insert 112 and bracket 114 can be made to be disposable , it is currently preferred that bracket 114 be reusable . as front face 122 is relatively thin , apertures 118 ( and the rest of bracket 114 ) can be cleaned and properly sterilized . insert 112 is preferable made of a medical grade plastic which can be machined and sterilized such as acetal or polycarbonate . insert 112 is discarded after a single use . as shown in fig1 , insert 112 can be made in two sections : a front section 136 and a rear section 138 . when front 136 and rear 138 sections are joined , front tubes 140 align with rear tubes 142 to form channels 116 . as was the case with front 24 and rear 26 portions of disposable template grid 10 , there are a number of different ways to join front 136 and rear 138 sections . for example , a shoulder on an outer edge of either front 136 or rear 138 section can engage a groove on the other section . alternatively , a pin ( or pins ) on either front 136 or rear 138 section can engage a slot ( or slots ) on the other section . by making insert 112 in two halves ( i . e ., front section 136 and rear section 138 ) and then mating the two halves together , the diameter and spacing of channels 116 need only be precisely controlled for a very small distance , i . e ., near an outer surface 144 of front section 136 and near an outer surface 146 of rear section 138 . as this allows most of front tubes 140 and rear tubes 142 to be made with much larger tolerances without adversely affecting the accuracy in placement and size of channels 116 , insert 112 can be manufactured at a cost and effort that makes disposability commercially practical . furthermore , if insert 112 is machined , the problems associated with precisely machining small diameter holes on a thick block are avoided . while the instant invention has been shown and described herein in what are conceived to be the most practical and preferred embodiments , it is recognized that departures , modifications , adaptations and variations may be made therefrom within and without departing from the scope of the invention , which is therefore not to be limited to the details disclosed herein , but is to be afforded the full scope of the claims so as to embrace any and all equivalent apparatus and articles .
a sterile disposable template grid system for positioning and implanting medical implants is disclosed . in one embodiment , the disposable template grid includes an attachment element that joins a front portion having front channels and a rear portion having rear channels so that the front channels align with the rear channels to form passages which allow medical implants to pass from the front portion through the rear portion . in another embodiment , the disposable template grid includes an insert having channels ; a bracket sized to removably receive and support the insert and having apertures ; and an alignment element for aligning the apertures with the channels to allow medical implants to pass from the apertures through the channels . although the disposable template grid can be used with a wide variety of implants , it is particularly well suited for the radioactive seed containing needles used in brachytherapy .