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Generation of portal film charts for 10‐MV x rays
Author(s) -
Faermann Sergio,
Krutman Yanai
Publication year - 1992
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.596865
Subject(s) - quality assurance , task group , dosimetry , materials science , air gap (plumbing) , optics , photon , computer science , medical physics , nuclear medicine , physics , medicine , composite material , engineering management , external quality assessment , pathology , engineering
An analytical method to generate portal film charts for 10‐MV photon beams, which takes into account the presence of the cassette front screen is presented. The selection of the best film–screen combination was based on the new AAPM recommendations for radiotherapy portal imaging [AAPM Rep. No. 24, AAPM Task Group No. 28 (1987)]: 2‐g/cm 2 ‐thick copper front screen and 0.4‐g/cm 2 ‐thick copper rear screen, and X‐OMAT TL Kodak unwrapped film. Doses at the film position were measured as a function of patient thickness, field size, air gap, and the results compared well with the doses derived from the analytical method: within ±15%. An optical density of 1.6 was selected for construction of the portal film charts. The application of the method for routine treatment planning quality assurance allows a quick and precise determination of the best exposures to the portal films.