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Range verification of particle beams in real time is considered a key for tapping the full potential of radio-oncological particle therapies. The novel technique of prompt gamma-ray timing (PGT), recently proposed and explored in first proof-of-principle experiments, promises range assessment at reasonable expense but challenges detectors, electronics, and data acquisition. Energy-selected time distributions have to be measured at very high throughput rates to obtain the statistics necessary for range verification with single pencil beam spots. Clinically applicable systems should provide a time resolution of about 200 ps, to be obtained with large (about 2” diameter) scintillators, detector loads in the few-Mcps range, and data acquisition rates around 1 Mcps, if possible with compact and inexpensive systems. Such requirements can be met best with CeBr3 scintillators read out with conventional photomultiplier tubes, coupled to commercial but customized electronics featuring high-resolution pulse digitization and fast digital signal processing. The paper deduces design parameters from the constraints given by typical treatment conditions, and presents first results obtained with prototype detectors and electronics developed in accordance with the derived specifications. [ABSTRACT FROM AUTHOR]

Proton and light ion beams are applied to the therapeutic irradiation of cancer patients due to the favorable dose deposition of these particles in tissue. By means of accelerated ions, a high dose can be accurately deposited in the tumor while normal tissue is spared. Since minor changes in the patient’s tissue along the beam path can compromise the success of the treatment, an in-vivo monitoring of the dose deposition is highly desired. Cameras detecting the prompt \gamma -rays emitted during therapy are under investigation for this purpose. Due to the energy spectrum of prompt \gamma -rays with a range between a few keV and several MeV, it is reasonable to consider the utilization of electron-positron pair production events to reconstruct the origin of these prompt photons. The combined use as a pair production and Compton camera is expected to increase its efficiency. We evaluated if a pair production camera could be suitable in this context by means of Monte-Carlo simulations. Modelling of the pair production events taking place in a prototype detector dedicated to Compton imaging were performed. We analyzed the efficiency of the detector system regarding pair production and Compton events. The most crucial property of this pair production camera is the angular resolution. The results of this work indicate that the spatial resolution of the considered detection system used as pair production camera is, for principal reasons, insufficient for an application to range assessment in particle therapy. Furthermore, the efficiency of the pair production camera under study is one order of magnitude lower than the efficiency of the setup applied to the detection of Compton events. [ABSTRACT FROM AUTHOR]