Experimental Estimation of Gamma and Electron Detection Ratios for Training and Evaluating Signal Discriminators for Intraoperative Probes

Radioguided surgery (RGS) for cancer resection is a widely performed practice for accurate localisation of cancerous tissue. The medical radioisotope ^99m Tc can be detected during RGS with the use of an intraoperative probe to detect cancerous tissue. For accurate localization, the internal conversion (IC) electrons from ^99m Tc are set as the target emission due to their shorter range in tissue. However, the inability to isolate the IC electrons and gamma emissions mean that a labelled dataset is not available in practice, yet this is required for training a discriminator. In this study, an experimental method relying on evaporation is proposed to obtain ground truth information relating to emissions present within the dataset using physics-informed modelling of the IC electron and gamma signals. By experimental design, both signals vary differently over time thus allowing the ratio between the two signal sources to be estimated. This ground truth ratio information has been measured and hence used i) to assess the intrinsic response of an intraoperative probe for IC electron detection, and ii) to evaluate experimentally different discriminator algorithms. Furthermore, the data can also be used to partially label a measured dataset, allowing both training and testing of discriminators with known ratios. In summary, an experimental method was proposed to allow the evaluation of detector sensitivities and the development of discriminators for unlabelled datasets.