Air-Kerma Determination of an HDR IR-192 Source

The seven-distance technique developed at the University of Wisconsin Accredited Dosimetry Calibration Laboratory is recognized as the U.S. national standard for HDR 192Ir calibration. Air-kerma strength determinations were performed for the Bebig model Ir2.A85-2 Ir-192 source using the seven-distance apparatus was compared against the air-kerma strength measurements by two reference well-type ionization chambers. Additionally, Monte Carlo techniques were used to predict a calibration coefficient for a Standard Imaging HDR1000 Plus well-type ionization chamber. The results of the simulations were compared to a measured calibration coefficient based on an HDR1000 Plus well-type ionization chamber and the air-kerma strength measurements made using the seven-distance apparatus. Radiochromic film exposures were also performed to qualitatively assess the dose distribution of the source in phantom.