Experimental and Monte Carlo endovascular dosimetry of a 192Ir source

Experimental and Monte Carlo dosimetry of a high dose rate (HDR) Ir-192 source, used for the brachytherapy of peripheral vessels is reported. The new high sensitivity radiocromic film (RCF) supplied by the manufacturer as HS-14, that presents only one active layer, was used for the source dosimetry in water phantom. The adopted experimental set-up seems to give low perturbation effects on the measurements of the optical density of the RCF. The agreement between the obtained experimental value of the dose rate constant D-Kr(10 mm, pi/2) = 1.11 +/- 0.02 cGyh(-1)/muGyh(-1) and the value reported in literature, confirmed the consistency of the HS-14 RCF calibration, obtained by the air kerma measurements. The RCF measurements at distances less than 10 mm from the source yielded the dose to water at the reference point, (D) over dot (2 mm, pi/2)/(K) over dot (r), the radial close function g(r) and the anisotropy function F(r,theta). The value (D) over dot (2 mm, pi/2)/(K) over dot (r) = 22.4 +/- 1.2 cGyh(-1)/muGyh(-1) is supplied with a 5.3% dose uncertainty due essentially to the uncertainty of the source position inside the catheter. Dose rate values around the HDR Ir-192 source have been estimated by mean of the EGS4 Monte Carlo system using a very well tested user code. The agreement of the dose rate constant, radial and anisotropy functions with the experimental results are well within the experimental uncertainties. Monte Carlo calculated tables, fully characterizing the dose distribution around the HDR Ir-192 endovascular brachytherapy source, are presented.