A computerized gamma probe simulator to train surgeons in the localization of sentinel nodes

Background The technique of sentinel node biopsy (SNB) may be used as a staging technique for cancer patients. SNB involves the localization of lymph nodes that have accumulated a radioactive tracer, and this requires surgeons to gain and demonstrate skills in the use of hand-held radiation detectors (gamma probes). Methods A computerized gamma probe simulator (GAPS) has been developed as a training tool to provide realistic simulations of the clinical distribution of radioactivity, without the use of radioactive materials, and a realistic simulation of the count rate response from a gamma probe. Electromagnetic spatial tracking of the surgeon's movement of the probe allows objective assessment of the user's accuracy in localizing a virtual sentinel node. The physical accuracy of the simulation has been validated, with a spat a accuracy of (0.06 mm), and a count rate error of 0.28%. Results The GAPS has been used in the training of 94 breast surgeons, with a mean error node localization of 3.8 mm (range, 0.1-16 mm) and a mean search time of 131 s (range 36-314 s), showing that objective feedback on performance can be given by the system. Modification to train for other sentinel node applications is simple, and the system has been used for training in the application of penile sentinel node surgery. Conclusion A computerized gamma probe simulator has been developed which provides realistic training tasks for surgeons in sentinel node biopsy, with a wide range of simulated clinical cases, allowing the objective assessment of a trainee's performance in the use of a hand-held gamma probe without the use of radioactive sources.