title: Investigation of photoneutron dose equivalent from high-energy photons in radiotherapy.
abstract: Spatial distribution of photoneutron dose equivalent during radiotherapy at different beam size, depth, and distance from a 15 MV linear accelerator was investigated with bubble detectors in a water phantom. The photoneutron dose equivalent was mainly from fast neutrons, and decreased with distance at a fixed field and with depth. Besides, photoneutron dose equivalent was slightly affected by beam size due to the variation of tungsten area exposed in the beam direction and photoneutrons occurred at the jaws. Fast photoneutron dose equivalent of shallow critical organs was represented still considerably outside the beam size.
authors.affiliation: Department of Radiological Technology, Yuanpei Institute of Science and Technology, No. 306, Yuan Pei Road, Hsinchu 300, Taiwan.
authors.forename: Jao-Perng
authors.initials: JP
authors.lastname: Lin
authors.forename: Wei-Chung
authors.initials: WC
authors.lastname: Liu
authors.forename: Chun-Chih
authors.initials: CC
authors.lastname: Lin
mesh_terms: D009502:Neutrons; D010315:Particle Accelerators; D019047:Phantoms, Imaging; D017785:Photons; D011829:Radiation Dosage; D018787:Radiation Oncology; D012542:Scattering, Radiation; D014414:Tungsten / Q000737:chemistry
chemical_list: D014414:Tungsten