title: Room scatter factor modelling and measurement error analysis of 192Ir HDR calibration by a Farmer chamber.
abstract: We introduce an empirical formula to directly calculate the room scatter factor in the calibration of (192)Ir HDR using a Farmer chamber. Compared to the data of Selvam et al (2001 Phys. Med. Biol. 46 2299), our formula is accurate to within 0.3%. Our method saves time because the room scatter can be obtained in one calculation rather than being deduced through a series of setups of different source-chamber distances. It could also be cost effective because a calibration jig might be no longer necessary. We only need to position the applicator and chamber at a fixed space in air and measure its distance. We also analysed the effects of two possible errors arising from ignoring the room scatter and the measurement error of the source-chamber distance. We recommend that the source-chamber distance should be at least 10 cm.
authors.affiliation: Institute of Biomedical Engineering, National Cheng-Kung University, Tainan 70101, Taiwan, People's Republic of China.
authors.forename: Liyun
authors.initials: L
authors.lastname: Chang
authors.forename: Sheng-Yow
authors.initials: SY
authors.lastname: Ho
authors.forename: Chen-Shou
authors.initials: CS
authors.lastname: Chui
authors.forename: Yi-Chun
authors.initials: YC
authors.lastname: Du
authors.forename: Tainsong
authors.initials: T
authors.lastname: Chen
mesh_terms: D055592:Biophysical Phenomena; D001703:Biophysics; D006801:Humans; D007496:Iridium Radioisotopes / Q000627:therapeutic use*; D015233:Models, Statistical; D009369:Neoplasms / Q000532:radiotherapy; D011874:Radiometry / Q000295:instrumentation* / Q000706:statistics & numerical data; D011880:Radiotherapy Planning, Computer-Assisted / Q000706:statistics & numerical data*; D012542:Scattering, Radiation
chemical_list: D007496:Iridium Radioisotopes