Use of bremsstrahlung radiation to identify hidden weak beta- sources: feasibility and possible use in radio-guided surgery

TL;DR

This study explores using bremsstrahlung X-ray detection with cadmium telluride sensors to identify hidden beta- sources in tissue, enhancing radio-guided surgery by detecting tumors concealed under several millimeters of tissue.

Contribution

We developed a cadmium telluride-based detector for bremsstrahlung X-rays, enabling detection of small residual tumors hidden beneath tissue layers, improving the capabilities of radio-guided surgery.

Findings

Detects 1 ml residuals with 1 kBq activity under 10 mm tissue

Achieves five sigma discrimination in less than 5 seconds

Demonstrates feasibility of bremsstrahlung detection for hidden tumor identification

Abstract

The recent interest in beta- radionuclides for radio-guided surgery derives from the feature of the beta radiation to release energy in few millimeters of tissue. Such feature can be used to locate residual tumors with a probe located in its immediate vicinity, determining the resection margins with an accuracy of millimeters. The drawback of this technique is that it does not allow to identify tumors hidden in more than few mm of tissue. Conversely, the bremsstrahlung X-rays emitted by the interaction of the beta- radiation with the nuclei of the tissue are relatively penetrating. To complement the beta- probes, we have therefore developed a detector based on cadmium telluride, an X-ray detector with a high quantum efficiency working at room temperature. We measured the secondary emission of bremsstrahlung photons in a target of Polymethylmethacrylate (PMMA) with a density similar to living tissue. The results show that this device allows to detect a 1 ml residual or lymph-node with an activity of 1 kBq hidden under a layer of 10 mm of PMMA with a 3:1 signal to noise, i.e. with a five sigma discrimination in less than 5 s.