BACKGROUND  
         [0001]    1. Field  
           [0002]    This disclosure relates generally to a surgical training and demonstration apparatus. More particularly, it relates to an apparatus and method for demonstrating and training surgeons in the techniques of intraoperative gamma detection and localization in biological systems.  
           [0003]    2. Background of the Related Art  
           [0004]    The detection of cancerous tissue using emissions from radionucleid labeled antibodies has been the subject of intense investigation for many years. Typically, the procedures involve the injection of radionucleid labeled antibodies into a patient. Over time, e.g. four to twenty-four hours, these labeled antibodies concentrate at tumor sites where they can be detected using sophisticated radiation detection equipment.  
           [0005]    The particular choice of radionucleid for labeling antibodies is dependent on its nuclear properties, the physical half life, the detection instrument capabilities, the pharmacokinetics of the radiolabeled antibody and the degree of difficulty of the labeling procedure. Early techniques utilized the  131 I radionucleid in conjunction with a relatively large and complex gamma camera positioned above the patient during the imaging process. This technique was less than ideal because the high energy gamma-photon emitted from  131 I is not well detected by traditional gamma cameras. In addition, the administered marker emissions deliver a high radiation dose to the patient. These techniques are also deficient in that, as tumor sites become smaller, the radionucleid concentrations tend to become lost, from an imaging standpoint, in the background or blood pool radiation necessarily present in the patient.  
           [0006]    In an effort to overcome these limitations, extensive research has been carried out in the field using much lower energy gamma emissions levels, for example,  125 I (27-35 kev), in conjunction with probe-type detection structure configured for insertion into the patient&#39;s body to minimize attenuation.  
           [0007]    This improved method of localization, differentiation and removal of cancerous tumors involves a surgical procedure wherein the patient suspected of having neoplastic tissue is administered an effective amount of a labeled antibody specific for neoplastic tissue. The antibody is labeled with a radioactive isotope exhibiting photo emissions of specific energy levels. These radioactive nuclides are well known to those skilled in the art and include Cl-36, Co-57, Co-60, Sr-90, Tc-99, Cs-137, Tl-204, Th-230, Pu-238, Pu-239, Am-241, Cr-51, Sr-85, Y-88, Cd-109, Ba-133, Bi-210, Ge-68, Ru-106, Iodine-125, Iodine-123, and Indium-III as well as other Alpha and/or Beta emitters.  
           [0008]    The surgical procedure is then delayed for a time interval to permit the labeled antibody to concentrate in the neoplastic tissue and to be cleared from normal tissue so as to increase the ratio of photon emissions from the neoplastic tissue to the background photon emissions. Once this time interval passes, the patient is surgically accessed and tissue within the operative field to be examined for neoplastic tissue is measured for a background photon emission count. Thereafter, a hand held probe is manually manipulated within the operative field adjacent tissue suspected of being neoplastic.  
           [0009]    Another common procedure which makes use of radionucleid labeled antibodies is known as Lymphatic Mapping and is used in the diagnosis and treatment of e.g. skin or breast cancers. This procedure permits the surgeon to map the drainage of cancerous lesions to determine the extent and location of their expansion in the body. Radionucleid labeled antibodies are injected at the site of the known lesion and permitted to circulate with the drainage of the lesion to the lymph nodes. Thereafter, using a radiation detector, the specific lymph nodes affected by the lesion can be identified and selectively treated.  
           [0010]    In carrying out the RIGS and lymphatic mapping procedures, the encountered radiation may be quite random and the background-to-concentration ratios may vary widely. To be used to its maximum effectiveness these procedures should be carried out by a highly trained surgeon experienced in the nuances of cancerous tissue detection. To date, surgeons have been trained using textbooks, observation and animal studies. While these are adequate to familiarize the surgeons with ideal or typical background-to-concentration readings, they are inadequate to simulate actual physiological patient conditions and, in the case of animal laboratory studies are quite expensive. Further, in animal studies neoplastic tissue is typically not inherently present, making simulation of background radiation and areas of concentration difficult at best.  
           [0011]    Accordingly, a need exists for a surgical training/demonstration structure which can be used in training surgeons in in vivo radiation detection without the need for animal laboratory studies.  
         SUMMARY  
         [0012]    The present disclosure shows a surgical training apparatus for training surgeons in the identification and localization of photon emissions from radioisotopes. The training apparatus includes a lower base portion having a plurality of notches therein. A cover is adapted to overlay the lower base portion and cover the plurality of notches. Identification indicia is included within each of the plurality of notches and on the cover. The cover identification indicia corresponds directly to the underlying notch when the training apparatus is in the closed position. At least one test source is disposed within one of the plurality of notches and is adapted to simulate a photo emission of a radioactive isotope. A probe device is used by the surgeon in conjunction with the training apparatus to familiarize the surgeon with the operation of the probe, and the principles and techniques associated with intraoperative gamma detection.  
           [0013]    A three-dimensional surgical training apparatus has several overlying layers each having a plurality of notches therein. Identification indicia can be included on the uppermost cover layer, and in each of the plurality of notches. The cover layer identification indicia corresponds directly to the underlying notch of each layer. At least one test source is disposed within one of the plurality of notches and is adapted to simulate a photo emission of a radioactive isotope. A probe device is used by the surgeon in conjunction with the three-dimensional training apparatus to familiarize the surgeon with the operation of the probe, and the principles and techniques associated with intraoperative gamma detection.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    Various embodiments of the subject surgical training apparatus are described herein with reference to the drawings wherein:  
         [0015]    [0015]FIG. 1 a  is a closed perspective view of the training apparatus;  
         [0016]    [0016]FIG. 1 b  is an open perspective view of the training apparatus;  
         [0017]    [0017]FIG. 2 a  is a perspective view of a check source used in the training apparatus;  
         [0018]    [0018]FIG. 2 b  is a partial perspective view of the training apparatus with a detection probe positioned for detection of concentrations of radiation;  
         [0019]    [0019]FIG. 3 a  is a broken away plan view of the training apparatus with a first check source positioned therein;  
         [0020]    [0020]FIG. 3 b  is a broken away plan view of the training apparatus with a second check source positioned therein;  
         [0021]    [0021]FIG. 4 a  is a schematic representation of a first scanning method used in the training apparatus;  
         [0022]    [0022]FIG. 4 b  is a schematic representation of a second scanning method used in the training apparatus;  
         [0023]    [0023]FIG. 5 a  is a plan view of the training apparatus with two check sources shown in phantom positioned therein;  
         [0024]    [0024]FIG. 5 b  is a plan view of the training apparatus with two check sources shown in phantom positioned differently therein;  
         [0025]    [0025]FIG. 6 a  is a graphical representation of a scanning detection method used with the training apparatus;  
         [0026]    [0026]FIG. 6 b  is a graphical representation of a scanning confirmation method;  
         [0027]    [0027]FIG. 7 illustrates two modes of operation for the probe device utilized by the disclosed training apparatus;  
         [0028]    [0028]FIG. 8 is a closed perspective view of the three-dimensional training apparatus;  
         [0029]    [0029]FIG. 9 is a partially open perspective view of the three-dimensional training apparatus; and  
         [0030]    [0030]FIG. 10 is an exploded perspective view of the three-dimensional training apparatus.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0031]    Referring to FIGS. 1 a  and  1   b , the training apparatus  50  has booklet configuration with an upper cover  52  and a lower base  54 . Cover  52  is hingedly connected to lower base  54  along a lateral edge  56 . Inside training apparatus  50 , lower base  54  includes a plurality of receiving notches  60  arranged in a grid-like spaced configuration. Notches  60  have a depth and a number designation  57  for identifying each notch location. Cover  52  also includes a plurality of number designations  58  which are also arranged in a grid-like configuration such that the number designations  58  correspond to the oppositely opposed number designation  57  when cover  52  and base  54  are disposed in the closed position as depicted in FIG. 1 a . Notches  60  can be any suitable shape and are shown as circular for purposes of illustration. Number designations  57  and  58  provide an identification system for assisting in the training of a surgeon in the use of the probe device  64 .  
         [0032]    The number designations  58  of cover  52  are shown in consecutive order starting at “1” and ending at “49”. The actual number in the space can be changed provided the notches in base  54  have the same number corresponding to the number designation on cover  52  when device  50  is in the closed position. Other identification indicia could be used, for example, letters, symbols, etc. without departing from the scope of this disclosure.  
         [0033]    [0033]FIG. 2 a  shows a test source  62  that is to be disposed in the notch designated “42”. Test source  62  has a gamma radiation (emission) value that can be varied according to the training being performed. For example, and for purposes of illustration, test source  62  has a 25 μc rating. After test source  62  has been inserted into the desired notch, cover  52  is closed over base  54 , and a probe-type detecting device  64  is placed over the training device  50  and is used by the surgeon to detect the previously positioned test source. This device  64  is preferably configured for insertion into a patient&#39;s body and is capable of detecting low levels of radiation. U.S. Pat. No. 4,801,803 to Denon et al. and U.S. Pat. No. 4,889,991 to Ramsey et al., both incorporated herein by reference, disclose a probe instrument and related control circuitry having the requisite sensitivity for use with relatively low energy radionuleids.  
         [0034]    When using the device  64  in conjunction with training apparatus  50 , the surgeon first calibrates the detector&#39;s control circuitry  66  to a radiation detection level and then moves the device over the apparatus while discerning increases in the radiation levels. These increases can then be localized until the source is pinpointed. By selecting appropriate nucleids, the detection process for tumor localization can be accurately and easily simulated.  
         [0035]    [0035]FIGS. 3 a  and  3   b  show examples of the positioning of two different test sources  62  and  63  within the training apparatus  50 . Test source  63  is positioned within the notch designated “17” and source  62  is positioned in notch designated “23”. The test sources are positioned within training device  50  without the knowledge of the surgeon being trained or tested.  
         [0036]    [0036]FIG. 4 a  shows a scanning technique  68  which is implemented during the use of training device  50 . As shown, scanning technique  68  is a diagonal technique where the passing of device  60  over the number designations  58  is performed in opposing diagonal directions for each adjacent diagonal row. FIG. 4 b  shows an alternative scanning technique  70  which is performed in a grid-like manner. The grid-like scanning technique  70  scans every other row or column of number designations  58 . This grid scanning technique can also be performed for every row and column, without departing from the scope of this disclosure.  
         [0037]    Once a test source has been positioned (FIGS. 3 a  and  3   b ), the surgeon utilizes a scanning technique (FIGS. 4 a  and  4   b ) to identify the “hot” node. Once the surgeon has identified a sufficient change in the probe device  64  reading, and believes to have identified the hot node, device  16  is to moved slightly away from the “hot” node in each direction to demonstrate confirmation of the node&#39;s location. The location of the test source is to be changed several times to assure the surgeon&#39;s ability to localize and identify the hot node.  
         [0038]    [0038]FIGS. 5 a  and  5   b  illustrate training procedures for a clinical application of the probe device. The 25 μc source  62  is introduced as the injection site, and the 1.5 μc source  63  is introduced as the sentinel node. In practice, the counts for these sources are equivalent to actual clinical cases.  
         [0039]    Referring to FIG. 5 a , the injection site source  62  is placed within notch  1  of base  54 , and the sentinel node source  63  is placed within notch  33  of base  54 , and the upper cover  52  is closed. The surgeon is then instructed to confirm the injection site by implementing a diagonal scanning technique (FIG. 4 a ). During the scanning procedure, it is important to emphasize the angling of the probe device away from the injection site. The diagonal scanning will provide higher count readings as the probe approaches the sources. The surgeon will notice the highest count reading at the injection site (source  62 ) with a drop off as the probe is moved from the injection site. The surgeon will also notice a count increase reading on the probe device as they approach the sentinel node (source  63 ).  
         [0040]    [0040]FIGS. 6 a  and  6   b  demonstrate the procedure for performing a “rollercoaster” confirmation of the localization of the respective sources. Using the placement of sources  62  and  63  of FIG. 5 a  as an example, the probe device is to be positioned at the point farthest away from an identified injection site (i.e., number designation 49). The surgeon will notice a low count reading on the probe device as this point. As shown in FIG. 6 b , as the probe device approaches the node source at number designation  33 , the count reading will rise, and then fall as the node is passed. As the probe device approaches the injection site source (i.e., at number designation 1), the count readings increase dramatically. The graphical representation of FIG. 6 b  shows the “rollercoaster” confirmation as it is based on the count readings produced by the probe device while scanning across the surface of training device  50 .  
         [0041]    The location of test sources  62  and  63  are changed for each training session, and can be positioned in any one of the spaces provided in training device  50  without departing from the scope of this disclosure.  
         [0042]    [0042]FIG. 5 b  shows another training procedure utilizing the disclosed training device  64 . During these diagnoses, a shine-through effect can deteriorate the accuracy at which the localization of the injection site and sentinel node. The shine through is defined where approximately 90% of the radio-colloid remains at the injection site and only 10% localizes in the effected nodal basin. For example, as shown in FIG. 5 b , the 1.5 μc source  63  has been positioned in notch  9  immediately adjacent 25 μc source  62  in notch designated 1. In this instance, since the injection site (i.e., number designation 1) is closed to the effected nodal basin (i.e., designation number 9), it may be difficult to distinguish those counts coming from the sentinel node versus counts coming from the injection site.  
         [0043]    In order to minimize shine-through, the primary lesion is excised prior to localization. For purposes of the training device  50 , the surgeon will, as before, continue to point/angle the probe device away from the injection site. In addition, a collimation feature of the probe device is utilized. FIG. 7 illustrates the use of the collimation feature of probe device  64 . In the uncollimated mode, the detection beam  72  is angularly dispersed from the end of device  64 . With the collimated mode, however, the dispersal of the detection beam is narrowed, and nearly eliminated, providing a more focused detection beam  74 . In the training example of FIG. 5 b , the uncollimated mode of probe device  64  will prevent the localization of the node due to the shine-through effect. By using the collimated detection beam, the surgeons ability to localize the node adjacent the injection site is significantly increased.  
         [0044]    As mentioned previously, the position of the test sources  62  and  63  are varied several times to familiarize the surgeon with all aspects of localization techniques.  
         [0045]    [0045]FIG. 8 shows a three-dimensional training device  80  having a cover layer  82  and overlapping underlying layers  84   a - 84   d . The cover  82  and layers  84   a - 84   d  are connected together using bolts  94   a - 94   c  and screw nuts  98   a - 98   c , respectively. Bolts  94   a - 94   c  pass through an upper plate  90 , cover  80 , layers  84   a - 84   d  and a lower plate  92  (FIG. 9) where they are secured using screw nuts  98   a - 98   c , respectively. Bolts  94   a - 94   c  and the corresponding screw nuts  98   a - 98   c  are a representative method of securing the layers of training apparatus  80 . Any other suitable known method or device may also be used for maintaining cover  82  and layers  84   a - 84   d  in an substantially overlying configuration.  
         [0046]    Each layer  84   a ,  84   b ,  84   c , and  84   d  includes a plurality of notches  101   a - 116   a ,  101   b - 116   b ,  101   c - 116   c , and  101   d - 116   d , respectively (FIGS.  8 - 10 ). Cover  82  has identification indicia  101 - 116  corresponding to the locations of the underlying notches, respectively. As described with reference to the training apparatus  50 , test sources  62  and  63  can be disposed in any one of the notches in any one of the layers  84   a -  84   d . The test source is positioned in a notch without the knowledge of the surgeon being trained or tested. The Surgeon then uses probe  64  to detect the location of the test source. The scanning motion or patterns of probe  64  shown in FIGS. 4 a  and  4   b  can be performed in three dimensions across the top of cover  82 , the sides of layers  84   a -  84   d , and along the bottom of lower layer  84   d . Thus, providing a more realistic simulation of tumor localization.  
         [0047]    It will be understood that various modifications may be made to the embodiments shown herein. For example, the first training device illustrated above need not be planar but can be fabricated in any desired shape or configuration. Also, the radionucleids can be selected from any group appropriate to training and/or demonstration. Therefore, the above description should not be construed as limiting, but merely as exemplifications as preferred embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto.
A surgical training apparatus and method are provided simulating a patient having background radiation emissions level and at least one concentrated source of radiation emissions. The apparatus includes a plurality of notches in a lower base portion for receiving test sources, and a cover for overlaying the lower base during the training procedures. Identification indicia is provided within each of the notches and on the cover to correlate the notch position with the closed cover surface. A radiation detection device is used to scan the surfaces in training surgeons for radiation identification and localization techniques.