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A practical method for the calculation of multileaf collimator shaped fields output factors
Author(s) -
Yuen K.,
AlGhazi M. S. A. L.,
Swift C. L.,
White C. A.
Publication year - 1999
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 - 10.1118/1.598754
Subject(s) - multileaf collimator , collimator , linear particle accelerator , imaging phantom , dosimetry , optics , physics , computer science , medical physics , mathematics , nuclear medicine , beam (structure) , medicine
Output factors of multileaf‐collimator (MLC) shaped radiation fields were measured for a commercial linear accelerator whose MLC leaves form parts of the upper collimator system. The approach of taking into account the reduced phantom scatter due to the MLC shaping on the output factor has previously been shown to be inadequate for this type of machine because of the effect of the MLC leaves on the collimator factor [Palta et al., Med. Phys. 23 , 1219–1224(1996)]. In this article, we present two forms of the collimator factor that give satisfactory agreement with measured values of the output factors of MLC‐shaped fields. The present method should be directly applicable to other linacs of similar MLC configuration. For clinical treatment planning, we believe the method is practical and accurate enough to be satisfactory. The equation for calculating the output factor requires only peak scatter and output factors of the machine. These are normally measured during machine commissioning.