Dosimetric characteristics of 192Ir sources used in interstitial brachytherapy

Dosimetric quantities of Ir-192 seed (5mm length) and wire (10mm length) brachytherapy sources have been determined. The quantities were measured based on the protocol introduced by the Radiation Therapy Committee of the American Association of Physicists in Medicine (AAPM) Task Group 43. Quantities such as dose rate constant, (Lambda), radial dose function, g(r), acid anisotropy function, F(r, theta) were experimentally determined and the geometry function, G(r, theta), was calculated. TLD measurements were made in a polymethyl methacrylate (PMMA) phantom of dimensions 25cm x 20cm x 5cm by means of LiF:Mg,Ti (TLD-100) dosimeters for distances of 1-10cm for g(r), and the same distances at angles of 0-180 degrees for F(r, theta). Dose rate constant for '"ZIr seed and wire were found to be 1.196 +/-5 and 1.082 +/-5%cGyh(-1)U(-1). respectively (1U=unit of air Kerma strength = 1 mu Gym(2)h(-1) = 1 cGycm(2)h(-1)). The obtained results for g(r), G(r; theta) and F(r, theta) are also presented and discussed. (C) 2001 Elsevier Science Ltd, All rights reserved.