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Dose calculation in static or dynamic off‐axis fields
Author(s) -
Loshek David D.,
Parker Timothy T.
Publication year - 1994
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 - 10.1118/1.597386
Subject(s) - collimator , collimated light , set (abstract data type) , point (geometry) , beam (structure) , field (mathematics) , dosimetry , physics , energy (signal processing) , algorithm , center (category theory) , computer science , mathematics , optics , nuclear medicine , geometry , medicine , laser , quantum mechanics , pure mathematics , programming language , chemistry , crystallography
X‐ray fields that are shifted away from the conventional central axis exhibit alterations in output, beam profile, and beam energy. An extension of a conventional dose calculation algorithm to correct for these perturbations is presented. This algorithm employs the product of three functions describing the dose at the center of the field at d max , the relative off‐center dose at d max , and the relative dose at depth along a fanline passing through the point of interest. The nature of the problem is characterized, a basic data set necessary to support the algorithm is described and an abridged set of data that may assist in the development of an independent collimator dose calculation capability is presented. The appropriateness of this technique for both conventional and dynamically collimated fields is illustrated.