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Scattering effects on the dosimetry of iridium‐192
Author(s) -
Serago Christopher F.,
Houdek Pavel V.,
Pisciotta Vincent,
Schwade James G.,
Abitbol Andre A.,
Lewin Alan A.,
Poole Darrell O.,
MarcialVega Victor
Publication year - 1991
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 - 10.1118/1.596602
Subject(s) - dosimetry , imaging phantom , iridium , scattering , ionization chamber , materials science , reduction (mathematics) , nuclear medicine , optics , physics , computational physics , ionization , mathematics , chemistry , medicine , geometry , ion , biochemistry , quantum mechanics , catalysis
Dosimetry calculations for iridium‐192 sources generally assume that a sufficient medium surrounds both the iridium source(s) and the point of calculation so that full scattering conditions exist. In several clinical applications the iridium sources may be anatomically located so that the full scattering requirement is not satisfied. To assess the magnitude of this problem, relative measurements were made with a small ionization chamber in phantoms near air and lung‐equivalent interfaces. Dose reduction caused by decreasing the volume of scattering material near these interfaces was then evaluated for a few clinical applications. The results show that reductions on the order of 8% may be expected at the interface with minimal dose reduction within the volume of the implant itself. In addition, the results indicate the verification of source strength of iridium sources in phantom require phantom dimensions determined by the source‐chamber separation distance.