Monte Carlo calculation of a 90Sr/90Y and an 192Ir sources for intravascular brachytherapy

The recent published AAPM TG-60 protocol proposed the dose calculation formalism for intravascular brachytherapy (IVBT). Various dose parameters for each type of radioactive sources are required in the formalism. These parameters include the dose rate constants (or the dose rate at reference position for a beta emitting source), the radial dose function and the anisotropy function. Using an EGS4/PRESTA version, the authors have calculated these parameters for a ⁹⁰Sr/⁹⁰ Y source and an ¹⁹²Ir source (encapsulated with stainless steel) in water. Their calculations cover a radial range of 0.5 to 10 mm, with the space resolution of 0.1 mm. Calculated results of these parameters are presented based on the dose calculation formalism recommended by the AAPM TG-60. The dose rate at reference position for the ⁹⁰Sr/⁹⁰Y source is 1.0875±0.003 Gy min ^-1 mCi^-1. The dose rate constant for the ¹⁹² Ir source is 23.76±0.06 cG hr^-1 U^-1, corresponding to an absolute dose rate of 89.22 cG hr^-1 mCi ^-1. The results of the radial dose functions and the anisotropy functions were presented in plotting form. The authors´ Monte Carlo results were compared with other published studies. Some of the dosimetric features for the sources studied were also discussed