title: [Determination of source position for four radiography systems with orthogonal projections in brachytherapy].
abstract: Four configurations of two X-ray tube positions are available for determining the position of a point using two orthogonal films. For each configuration, there are many formulas for calculating the coordinate of a point: the least squares methods with and without physical meaning, such as six sets of geometrical solutions, an approximation method with constant magnifications and so on. It is troublesome for a person in charge of treatment planning to directly derive a formula or select an appropriate formula from numerous ones for the four configurations. Thus, a method to easily apply the published formula for a configuration to the other three configurations is described in simulations and a clinical case using rotation matrixes of the right-handed coordinate system. Each diagonal element of the rotation matrixes is 1 or -1, and the other elements are 0.
authors.affiliation: Department of Radiotherapy, Saitama Cancer Center.
authors.forename: K
authors.initials: K
authors.lastname: Tabushi
authors.forename: S
authors.initials: S
authors.lastname: Itoh
authors.forename: M
authors.initials: M
authors.lastname: Sakura
authors.forename: S
authors.initials: S
authors.lastname: Kato
authors.forename: T
authors.initials: T
authors.lastname: Kazumoto
authors.forename: Y
authors.initials: Y
authors.lastname: Nakamura
authors.forename: T A
authors.initials: TA
authors.lastname: Iinuma
authors.forename: T
authors.initials: T
authors.lastname: Arai
authors.forename: T
authors.initials: T
authors.lastname: Irifune
mesh_terms: D001918:Brachytherapy / Q000379:methods*; D003198:Computer Simulation; D005260:Female; D006801:Humans; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D002583:Uterine Cervical Neoplasms / Q000532:radiotherapy