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Over‐response of tissue‐equivalent ionization chambers at low energies: Effect of high‐ Z surface contamination
Author(s) -
Hedrick W. R.,
Hykes D. L.,
Starchman D. E.
Publication year - 1984
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 - 10.1118/1.595454
Subject(s) - contamination , ionization chamber , ionization , photon , materials science , atomic physics , chemistry , physics , optics , ion , ecology , organic chemistry , biology
Inner wall surface contamination of an ionization chamber by high‐ Z materials can produce an over‐response to low‐energy photons which is greatly underestimated by the percentage composition of the contaminant in the entire chamber. Experience with a chamber contaminated in such a manner is presented. Examples are included which illustrate the magnitude of possible clinical effects from low‐energy units which have been calibrated with a chamber contaminated with a thin layer of relatively high‐ Z material.