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Penumbral measurements in water for high‐energy x rays
Author(s) -
Dawson D. J.,
Schroeder N. J.,
Hoya J. D.
Publication year - 1986
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 - 10.1118/1.595963
Subject(s) - ionization , ionization chamber , physics , asymmetry , atomic physics , optics , nuclear physics , ion , quantum mechanics
Ionization chambers of varying inside diameter have been used to investigate the penumbral region of 6 0 Co, 6‐MV, and 31‐MV x‐ray beams. Measurements were made in water at varying depths up to 25 cm for a square field of side length 10 cm. The dependence of the penumbral widths on both the inside diameter of the ionization chamber and the depth in water is established along with the asymmetry of the penumbral distributions about the 50% level. A standard correction is indicated to eliminate the dependence of the measured penumbral widths on the inside diameter of the ionization chamber.