title: Photoneutron contamination from an 18 MV Saturne medical linear accelerator in the treatment room.
abstract: Dose escalation with high-energy X rays of medical linear accelerators (linacs) in radiotherapy offers several distinct advantages over the lower energy photons. However, owing to photoneutron reactions, interaction of high-energy photons (>8 MV) with various high-Z nuclei of the materials in the linac head components produces unavoidable neutrons. The aim of this study was to evaluate the photoneutron dose equivalent per unit therapeutic X-ray dose of 18 MV, GE Saturne 20 linac in the treatment room using Monte Carlo (MC) MCNP linac head full simulation as well as thermoluminescence dosemeter measurements. This machine is one of the old linac models manufactured by General Electric Company; however, it is widely used in the developing countries because of low cost and simple maintenance for radiotherapy applications. The results showed a significant photoneutron dose from Saturne 20 linac head components especially at distances near the linac head (<150 cm). Results of this work could be used in several applications, especially designing bunker and entrance door shielding against neutrons produced by photoneutron reactions in GE Saturne 20. However, a detailed cost optimisation for a specific room would require a dedicated calculation.
authors.affiliation: Department of Medical Physics and Medical Engineering, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Mostafa
authors.initials: M
authors.lastname: Khosravi
authors.forename: Daryoush
authors.initials: D
authors.lastname: Shahbazi-Gahrouei
authors.forename: Keyvan
authors.initials: K
authors.lastname: Jabbari
authors.forename: Mehdi
authors.initials: M
authors.lastname: Nasri-Nasrabadi
authors.forename: Milad
authors.initials: M
authors.lastname: Baradaran-Ghahfarokhi
authors.forename: Zahra
authors.initials: Z
authors.lastname: Siavashpour
authors.forename: Ruhollah
authors.initials: R
authors.lastname: Gheisari
authors.forename: Behnam
authors.initials: B
authors.lastname: Amiri
mesh_terms: D003198:Computer Simulation; D006801:Humans; D008962:Models, Theoretical; D009010:Monte Carlo Method; D009502:Neutrons; D010315:Particle Accelerators; D017785:Photons; D011829:Radiation Dosage; D011882:Radiotherapy, High-Energy; D013819:Thermoluminescent Dosimetry