Radiochromic film measurement of anisotropy function for high-dose-rate Ir-192 brachytherapy source.
The dose distribution produced by the high-dose-rate (HDR) 192Ir source is inherently anisotropic due to self-absorption by the high-density source core, oblique filtration by the source capsule and the asymmetric geometry of the source capsule. To account for the dose distribution anisotropy of brachytherapy sources, AAPM Task Group No 43 has included a two-dimensional anisotropy function, F(r, theta), in the recommended dose calculation formalism. Gafchromic HS radiochromic film (RCF) was used to measure anisotropy function for microSelectron HDR 192Ir source (classic/old design). Measurements were carried out in a water phantom using specially fabricated PMMA cylinders at radial distances 1, 2, 3, 4 and 5 cm. The data so generated are comparable to both experimental and Monte Carlo calculated values for this source reported earlier by other authors. The RCF method described in this paper is comparatively high resolution, simple to use and is a general method, which can be applied for other brachytherapy sources as well.
Cattedra di Fisica Medica, Dipartimento di Scienze Cliniche e Biologiche, Universita degli Studi dell' Insubria, 21100 Varese, Italy. sdsharma_barc@rediffmail.com
S D
SD
Sharma
C
C
Bianchi
L
L
Conte
R
R
Novario
B C
BC
Bhatt
D000465:Algorithms; D016880:Anisotropy; D001918:Brachytherapy / Q000295:instrumentation* / Q000379:methods*; D002138:Calibration; D004307:Dose-Response Relationship, Radiation; D005373:Film Dosimetry / Q000379:methods*; D006801:Humans; D007496:Iridium Radioisotopes; D009010:Monte Carlo Method; D019047:Phantoms, Imaging; D011874:Radiometry; D011880:Radiotherapy Planning, Computer-Assisted; D012984:Software; D014867:Water; D014962:X-Ray Film
D007496:Iridium Radioisotopes; D014867:Water