Perturbation of radiotherapy beams by radiographic film: measurements and Monte Carlo simulations
1999; IOP Publishing; Volume: 44; Issue: 7 Linguagem: Inglês
10.1088/0031-9155/44/7/314
ISSN1361-6560
AutoresNatalka Suchowerska, Peter Hoban, Alastair Davison, Peter Metcalfe,
Tópico(s)Radiation Effects and Dosimetry
ResumoRadiographic film is an established practical tool used in the measurement of the dose distribution for radiotherapy purposes. The accuracy and reproducibility of film optical density as an indicator of dose has been associated with several factors including photon energy, processing conditions and film plane orientation. Few studies have investigated the factors causing variability in film dosimetry, due to the difficulty of separating the individual contributions. The effect that a sheet of radiographic film in a water phantom has on its response to a 6 MV photon and a cobalt-60 teletherapy beam, when orientated perpendicular and parallel to the beam central axis, is reported. Monte Carlo generated spectra were used to calculate collision kerma (Kcoll) for water and film elements. Measured and calculated results indicate a potential over-response at 25 cm depth of the order of 14±2.4% and 18±6.0% respectively for 6 MV photons and 15±3.4% and 32±4.5% respectively for a cobalt beam.
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