title: Calculation of three-dimensional photon primary absorbed dose using forward and backward spread dose-distribution functions.
abstract: This paper describes a method of calculating three-dimensional (3-D) photon primary absorbed dose in a homogeneous or heterogeneous medium. The method is based on a technique of convolving a pair of forward and backward spread dose-distribution functions with the primary water collision kerma distribution. Both spread dose-distribution functions can be constructed by analyzing the zero-area tissue-maximum ratio, the primary absorbed dose near the beam exit surface, and the laterally spread dose distribution. Primary absorbed dose calculations are performed along the beam axis for 10-MV x rays. The characteristic patterns of primary dose in heterogeneous phantoms containing an aluminum or lunglike material slab can be obtained.
authors.affiliation: School of Allied Medical Sciences, Hirosaki University, Aomori-ken, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Iwasaki
mesh_terms: D008961:Models, Structural; D010315:Particle Accelerators; D011827:Radiation; D011829:Radiation Dosage; D012542:Scattering, Radiation; D014867:Water
chemical_list: D014867:Water