Radiation source detection for the accurate location of lymph node metastases using robotic forceps-type coincidence radiation detector

We have developed a forceps-type coincidence radiation detector for supporting lymph node dissection in esophageal cancer treatment. For precise detecting, this study aims to measure the 2D point-spread function of the detector at three difference tip angles, to devise a method to determine the position of a point source using the 2D point-spread function.

The 2D sensitivity distribution on the surface of the detector was investigated to assess sensitivity variation caused by differences in the relative positions of the detector and radiation source. Based on the results, we identified the peak sensitivity value and proposed a detection method using this value. We evaluated the effectiveness of the proposed method by detecting radiation source location using this simulated distribution.

From the radiation sensitivity distribution measurements, we observed a gradual decrease in radiation detection sensitivity from the center toward the edges of the detector surface. Additionally, we verified that the peak sensitivity value was attainable. Through the basic verification of the detection method, we confirmed that the radiation source location could be detected within a maximum error of 1.4 mm.

We developed a peak value search method aimed at mitigating sensitivity variations by leveraging the sensitivity distribution across the detector surface. The proposed device is thought to be able to quantitatively evaluate the desired target assuming that the field of view could be limited to the area clamped by the detector. As a next research step, more precise search methods should be verified in an environment resembling the one of the target clinical uses.