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Output factors for blocked fields.

E M Dean·J B Davis
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Abstract

This study investigates the output from blocked treatment fields with 6 MV and 18 MV photons. Square fields, defined by collimators, were blocked down to smaller symmetrical square, rectangular and asymmetrical rectangular fields using blocks on a tray beneath the collimators. Up to 7.5% difference was found between the output measured for the blocked field and the output calculated using a collimator output factor for the surface field size. A method is described by which output factors for the blocked fields can be measured and used in practice. Three methods of approximating these output factors are also presented.

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HumansModels, StructuralRadiometryRadiotherapy DosageRadiotherapy, High-EnergyJournal Article

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E M Dean, J B Davis. 1992. Output factors for blocked fields.. https://doi.org/10.1259/0007-1285-65-774-517

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