Single module of a Compton camera detector for online beam range monitoring in proton therapy*

The key advantage of proton therapy over conventional radiotherapy is the dose deposition pattern: unlike X-rays, protons are fully stopped in patient's tissues with a distinct maximum at the end of their range: the Bragg peak. This enables precise coverage of a tumor volume while sparing the nearby healthy tissues. However, accurate control of the proton beam range is still considered a challenge. The SiFi-CC (SiPM and scintillating Fiber based Compton Camera) group develops a method of in vivo proton range monitoring with a Compton camera. Such a detector exploits the Compton effect and registers prompt gamma rays emitted in interactions of protons with the tissues' nuclei. Our design is a trade-off between the camera performance and its cost. In our approach, both detector modules (scatterer and absorber) will consist of stacked scintillating fibers with dual readout via silicon photomultipliers. Our simulation studies have shown that such a solution is feasible and appropriate for online range monitoring in proton therapy. The scintillating material and fiber coating were chosen based on an extensive study of the fiber properties. I am going to present the overview of the SiFi-CC project and discuss the performance of a single module of a Compton camera in proton beam conditions.