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A three layer Compton telescope for dose monitoring in hadron therapy is under development at IFIC - Valencia. It will consist of three detector layers and each layer will be made of a continuous LaBr 3 crystal coupled to four Silicon Photomultiplier (SiPM) arrays. A prototype made of two detector layers has already been assembled and tested. The detector layers consist of a 32×36×5 mm3 and 32×36×10 mm3 LaBr 3 crystal, each coupled to four SiPM arrays. The front-end electronics of each detector is based on the VATA64HDR16 application specific integrated circuit (ASIC). The gamma rays coming from a 22Na source have been detected with the two detector layers working in time coincidence, allowing energy and position estimation.

Hadron-therapy (HT) aims to treat tumors by maximizing the dose released to the target and sparing the dose to normal tissues. For a successful outcome it is very important to determine where the maximum dose is deposited; therefore range verification is necessary for treatment optimization and patient safety. Secondary positron emitting isotopes and prompt gamma radiation are produced after the hadron beam passage. This secondary radiation coming from tissue activation could be used for quality control of treatment, provided that it can be detected and employed to reconstruct the beam path using imaging techniques. This is one of the main goals of the ENVISION project: to evaluate and develop on-line monitoring devices for HT, like PET for detecting the annihilation photons from positrons and Compton Cameras (CCs) for prompt gamma radiation detection. In both technologies high sensitivity is required to increase the signal-to-noise ratio of the reconstructed image for a given therapeutic dose. This simulation study focuses on the sensitivity optimization of such devices, PET and CC, taking into account its use and constraints for on-line HT monitoring. Several configurations of both technologies have been investigated using sources generated from hadron beams. In the case of PET data, the time-of-flight (TOF) information has been included too. For individual hadron beams acquired after 5 minutes, differences in range of 3 mm are detected for all the PET configurations, except for the partial-ring of 60 cm diameter. In addition, patient data from a carbon ion treatment at GSI have been simulated and reconstructed. The system with higher sensitivity and angular sampling recovers more accurately areas with no activity (nasal cavity). In the case of the CC data, the quality of the reconstructed image when using 2-interaction events is notably improved when the detector layers are placed covering a larger solid angle.