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Choice of material for HVL measurements in megavoltage x‐ray beams
Author(s) -
Meli Jerome A.,
Nath Ravinder
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 - 10.1118/1.595794
Subject(s) - half value layer , dosimetry , materials science , beam (structure) , atomic number , ionization , ionization chamber , effective atomic number , quality (philosophy) , x ray , laser beam quality , optics , nuclear medicine , physics , atomic physics , radiation , medicine , laser beams , ion , laser , quantum mechanics , radiation shielding
The relative sensitivity of the half‐value layer (HVL) method as a quality index for megavoltage x‐ray beams is examined by theoretical calculation and experimental measurements for 4‐, 6‐, 10‐, and 25‐MV x‐ray beams. It is shown that lower atomic number materials are more sensitive to beam quality changes than higher atomic number materials, and that aluminum is a reasonable choice of material for HVL measurements in megavoltage x‐ray beams. Further, it was found that the HVL in aluminum or polystyrene is a more sensitive index of spectral quality than the ionization ratio method, recommended by recent dosimetry protocols.