Phenomenological models for intraoperative positron emission surface imaging using handheld probes

One of the major issues in cancer resection is to guarantee that the complete tumor is included within the extracted tissue. Today beyond the eye of the surgeon, the only intraoperative confirmatory technique is the use of frozen sections. Novel methods [1] have suggested lately the use of positron-emitting radiotracers for controlling resection borders by imaging the radiotracer distribution on the tumor bed. If successful, this method can provide information complementary to frozen sections, such as a better spatial resolution and the possibility of evaluating the borders iteratively. Furthermore, in some cases where frozen section biopsy is not standardized for specific tissues (like in bonny structures [2]), surface radioactivity imaging can be a break-through. Generating 3D surface images of the positron emission distribution requires however proper models of the detection process if meant to be done using one dimensional handheld probes. In this paper, we introduce phenomelogical models for positron detection using handheld beta probes as logical extensions of the methods proposed in [1]. These models were implemented, their parameters determined and validated experimentally. By introducing more a priori information in this yet experimental imaging modality we strongly believe that its quality can be boosted and thus it can be brought closer to application towards a securer cancer resection.