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The effect of scattered radiation in 6 0 Co beams on wall correction factors for ionization chambers
Author(s) -
McEwan A. C.,
Smyth V. G.
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 - 10.1118/1.595930
Subject(s) - monte carlo method , dosimetry , ionization chamber , physics , radiation , photon , ionization , atomic physics , stopping power , nuclear physics , computational physics , optics , nuclear medicine , ion , mathematics , detector , medicine , statistics , quantum mechanics
The A wall correction factors used in dosimetry protocols are obtained by Monte Carlo methods that assume 6 0 Co beams equivalent to 1.25‐MeV radiation. Real 6 0 Co beams contain lower energy components; in addition, A wall is defined differently by different authors. In the present work, A wall as defined by Rogers, Bielajew, and Nahum (1985) has been calculated by Monte Carlo methods at several energies, for a graphite cavity chamber, using the revised stopping‐power data of Seltzer and Berger (1982). It is concluded that the true value of A wall for chambers designed for use in 6 0 Co beams will not move more than 0.1% below the value calculated for 1.25‐MeV photons.