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Systematic patient-dose errors for 4- and 10-MeV microwave linear accelerators associated with rectangular collimator settings.

R F Moyer
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Abstract

Systematic patient-dose errors relating to standard equivalent-square approximations and movable collimator-exchange effect were evaluated for rectangular fields of photon beams from 4- and 10-MeV microwave electron accelerators (Varian Clinac 4 and Clinac 18). Errors approached 2.5% at nominal treatment depths for highly elongated rectangular fields. The collimator-exchange effect should be considered when (a) evaluating ionization-chamber stem effect, (b) specifying relative output factors for rectangular fields, and (c) evaluating equivalent-square-field algorithms.

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R F Moyer. 1978. Systematic patient-dose errors for 4- and 10-MeV microwave linear accelerators associated with rectangular collimator settings.. https://doi.org/10.1148/129.3.803

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