Premium
Determination of electron beam output factors for a 20‐MeV linear accelerator
Author(s) -
Mills Michael D.,
Hogstrom Kenneth R.,
Fields Robert S.
Publication year - 1985
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 - 10.1118/1.595674
Subject(s) - linear particle accelerator , square (algebra) , field (mathematics) , beam (structure) , physics , electron , cathode ray , computational physics , particle accelerator , atomic physics , reference data , field size , optics , nuclear physics , mathematics , computer science , geometry , database , pure mathematics
The demands of a busy clinic require that basic machine calculations be performed as accurately, rapidly, and simply as possible. For the electron beam of the Therac 20 Saturne linear accelerator, a method suitable for a programmable calculator is described to predict the dose output from the measurement of selected fields. One‐dimensional output factors were measured; these are defined as output factors of rectangular fields where one side is always equal to the side of the square reference field. The output of an arbitrary rectangular field X , Y is given by the product of the output factors OF( X , Y )=OF( X ,10)×OF(10, Y ), where 10 is the side of the square reference field. The measured data indicate that the output of very large rectangular and square fields is underestimated using this method for the lower energies. A correction factor of the form CF = C ×[( X −10)( Y −10)/‖( X −10)( Y −10)‖ 1 / 2 ] results in agreement with measured data to within 1.5% for all energies.