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Output calibration in solid water for high energy photon beams
Author(s) -
Reft Chester S.
Publication year - 1989
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 - 10.1118/1.596423
Subject(s) - photon , calibration , absorption (acoustics) , photon energy , dosimetry , polystyrene , stopping power , energy (signal processing) , materials science , computational physics , nuclear physics , physics , atomic physics , optics , nuclear medicine , nuclear magnetic resonance , detector , medicine , quantum mechanics , polymer
The AAPM Protocol recommends the use of water, polystyrene or acrylic media for measuring the output of high energy photon beams. It provides the appropriate restricted mass stopping powers and mass energy absorption coefficients for converting the dose to these media to dose to water. A water‐equivalent solid has been developed for dosimetric applications [C. Constantinou, F. Attix, and B. Paliwal, Med. Phys. 9 , 436 (1982)]. Calculated values for the restricted mass stopping powers and mass energy absorption coefficients have been published for this material. [A. Ho and B. Paliwal, Med. Phys. 13 , 403 (1986)]. The accuracy of these calculations was investigated by making output measurements, following the Protocol, with a Farmer type chamber in four materials for Co‐60, 4, 6, 10, 18, and 24 MV photon beams. The results show that the scaled dose to water for the different media agree to better than 1%, and the analysis supports the methodology of the Protocol for obtaining the dose to water from the different media.