Affiliations: Department of Radiation Oncology, Peggy and Charles Stephenson Cancer Center, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
Correspondence:
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Corresponding author: Yong Chen, Department of Radiation Oncology, Peggy and Charles Stephenson Cancer Center, The University of Oklahoma Health Sciences Center, 800 N.E. 10th St., OKCC L100, Oklahoma City, OK 73104, USA. Tel.: +1 405 271 3220; Fax: +1 405 271 8297; E-mail: [email protected].
Abstract: In vivo range verification methods will reveal information about the penetration depth into a patient for an incident proton beam. The prompt gamma (PG) method is a promising in vivo technique that has been shown to yield this range information by measuring the escaping MeV photons given a suitable detector system. The majority of current simulations investigating PG detectors utilize common scintillating materials ideal for photons within a low neutron background radiation field using complex geometries or novel designs. In this work we simulate a minimal detector system using a material ideal for MeV photon detection in the presence of a significant neutron field based on the Cherenkov phenomenon. The response of this selected material was quantified for the escaping particles commonly found in proton therapy applications and the feasibility of using the PG technique for this detector material was studied. Our simulations found that the majority of the range information can be determined by detecting photons emitted with a timing window less than ∼50 ns after the interaction of the proton beam with the water phantom and with an energy threshold focusing on the energy range of the de-excitation of 16O photons (∼6 MeV). The Cherenkov material investigated is able to collect these photons and estimate the range with timescales on the order of tens of nanoseconds as well as greatly suppress the signal due to neutron.
Keywords: Proton therapy, GEANT4, Monte Carlo, Cherenkov, prompt gamma
