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Measurement of the source size of a 6‐ and 18‐MV radiotherapy linac
Author(s) -
Loewenthal E.,
Loewinger E.,
BarAvraham E.,
Barnea G.
Publication year - 1992
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 - 10.1118/1.596812
Subject(s) - microdensitometer , linear particle accelerator , optics , slit , materials science , dosimetry , medical imaging , radiation , nuclear medicine , radiation therapy , beam (structure) , physics , medicine , radiology
The quality of portal imaging is strongly affected by the source size of the radiotherapy machine. The effective source size of the dual‐energy clinac 1800 (6 and 18 MV) was measured with a 50 μm wide and 120 mm long slit formed by two tungsten‐copper alloy blocks. A series of slit images were obtained by translating the slit horizontally. The images were analyzed using a microdensitometer. The measured data was simulated using an analytical model of the source and its size was derived by a best‐fit analysis. For both energies the FWHM was found to be 1.5±0.1 mm.