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A procedure to determine the radiation isocenter size in a linear accelerator
Author(s) -
González A.,
Castro I.,
Martı́nez J. A.
Publication year - 2004
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 - 10.1118/1.1755491
Subject(s) - isocenter , collimator , linear particle accelerator , optics , physics , rotation (mathematics) , dosimetry , medical imaging , radius , radiation , computer science , nuclear medicine , imaging phantom , beam (structure) , artificial intelligence , medicine , computer security
Measurement of radiation isocenter is a fundamental part of commissioning and quality assurance (QA) for a linear accelerator (linac). In this work we present an automated procedure for the analysis of the stars‐shots employed in the radiation isocenter determination. Once the star‐shot film has been developed and digitized, the resulting image is analyzed by scanning concentric circles centered around the intersection of the lasers that had been previously marked on the film. The center and the radius of the minimum circle intersecting the central rays are determined with an accuracy and precision better than 1% of the pixel size. The procedure is applied to the position and size determination of the radiation isocenter by means of the analysis of star‐shots, placed in different planes with respect to the gantry, couch and collimator rotation axes.