title: Prompt gamma-ray emission from biological tissues during proton irradiation: a preliminary study.
abstract: In this paper, we present the results of a preliminary study of secondary 'prompt' gamma-ray emission produced by proton-nuclear interactions within tissue during proton radiotherapy. Monte Carlo simulations were performed for mono-energetic proton beams, ranging from 2.5 MeV to 250 MeV, irradiating elemental and tissue targets. Calculations of the emission spectra from different biological tissues and their elemental components were made. Also, prompt gamma rays emitted during delivery of a clinical proton spread-out Bragg peak (SOBP) in a homogeneous water phantom and a water phantom containing heterogeneous tissue inserts were calculated to study the correlation between prompt gamma-ray production and proton dose delivery. The results show that the prompt gamma-ray spectra differ significantly for each type of tissue studied. The relative intensity of the characteristic gamma rays emitted from a given tissue was shown to be proportional to the concentration of each element in that tissue. A strong correlation was found between the delivered SOBP dose distribution and the characteristic prompt gamma-ray production. Based on these results, we discuss the potential use of prompt gamma-ray emission as a method to verify the accuracy and efficacy of doses delivered with proton radiotherapy.
authors.affiliation: Department of Radiation Physics, Unit 94, The University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Blvd, Houston, TX 77030, USA. jcpolf@mdanderson.org
authors.forename: J C
authors.initials: JC
authors.lastname: Polf
authors.forename: S
authors.initials: S
authors.lastname: Peterson
authors.forename: G
authors.initials: G
authors.lastname: Ciangaru
authors.forename: M
authors.initials: M
authors.lastname: Gillin
authors.forename: S
authors.initials: S
authors.lastname: Beddar
mesh_terms: D003198:Computer Simulation; D005720:Gamma Rays; D006801:Humans; D008954:Models, Biological; D009010:Monte Carlo Method; D010865:Pilot Projects; D061766:Proton Therapy; D011829:Radiation Dosage; D011874:Radiometry / Q000379:methods*; D012542:Scattering, Radiation; D011522:Protons
chemical_list: D011522:Protons