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Speculation concerning average tissue–air ratio determinations for rotational 60 Co radiation therapy treatment planning
Author(s) -
Morin R. L.,
Raeside D. E.,
Wizenberg M. J.
Publication year - 1981
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 - 10.1118/1.594941
Subject(s) - homogeneous , radiation , radiation treatment planning , dosimetry , nuclear medicine , radiation therapy , physics , chemistry , computational physics , optics , medicine , radiology , thermodynamics
The question of the number of radii which are necessary to accurately determine the average tissue–air ratio (TAR) to be used in 60 Co rotational radiation therapy treatment planning was studied using an analytical expression for the TAR as a functon of depth and field size, and an elliptic, homogeneous patient cross section. It was found that for such a contour 12 radii determine the average TAR to within 0.01% of the value obtained using 360 radii.