Premium
Evaluation of tissue‐air ratios and tissue‐maximum ratios with the photon energy‐fluence absorption dose model
Author(s) -
Ahuja Sain D.,
Stroup Steven L.,
Bolin Marion G.
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 - 10.1118/1.594936
Subject(s) - fluence , percentage depth dose curve , imaging phantom , photon , absorption (acoustics) , materials science , dosimetry , optics , photon energy , absorbed dose , beam (structure) , nuclear medicine , atomic physics , physics , ionization chamber , radiation , ion , laser , medicine , quantum mechanics , ionization
Values of tissue‐air ratio (TAR) and tissue‐maximum ratio (TMR) have been calculated with the photon energy‐fluence absorption dose model, at depths d > d n (depth of dose normalization) in a homogeneous water phantom, for Co‐60 γ‐ray, and 4, 6, 10, 14, and 45 MV p x‐ray beams of EQS (the side of the equivalent square) up to 20 cm. It has been found that by (i) slightly altering the formula for the depth modification factor so that it depends on the difference ( d − d n ) rather than d alone; and (ii) permitting E , the effective energy of the beam, to vary with EQS for some x‐ray beams, it is possible for the model to reproduce within 2.5% the measured data at depths d > d n , on TAR, TMR and PDD (the central axis percent depth dose), for any source to surface distance.