Abstract
Aims: Breast cancer patients often have associated metastases, caused by cancerous cells spreading through the lymphatic system to other areas of the body. As a result, it is common to remove and assess the sentinel lymph node (SLN) during the surgical removal of the tumour. To localise the SLN, an injection of 99mTc-Nanocoll is administered interstitially or intradermally which is transported to SLNs via the lymphatic system. A nuclear medicine scan is then acquired. A gamma probe is used to locate the SLN during the surgical procedure with the aid of the nuclear medicine scan images. The aim of this study was to optimise the performance of an intraoperative gamma probe system (Europrobe) having both scintillation and semiconductor probes for more accurate detection of SLN in melanoma and breast cancer patients.

Methods: The surgical Europrobe system is equipped with one scintillation CsI(Tl) detector and one semiconductor CdTe detector. Tests were performed against The National Electrical Manufacturers Association (NEMA) guidelines using an in-house developed phantom.

Results The CsI(Tl) detector has superior sensitivity and better side shielding effectiveness. The CdTe probe has better spatial and energy resolutions.

Conclusion : It is not possible for a probe to have optimum performance for all parameters, so a compromise must be reached depends on clinical and surgical preference. The Europrobe has scintillation and semiconductor probes, which allows the user to choose the most suitable probe for the intended application. The scintillation probe has high sensitivity, which is important for detection of low nodal activity, or deep-seated nodes. The semiconductor probe has superior spatial and energy resolutions, which are important for accurate localisation and scatter rejection.