Calculation on the dose distribution in water phantom of high-dose-rate iridium-192

To provide the dose data needed for optimizing treatment in afterloading therapy, the dose distribution was calculated in water phantom for high-dose-rate iridium-192 with Monte Carlo approach based the Ir source structure of Nucletron Corporation. The code EGSnrc was used when the dose was calculated at the outside of stainless steel shell along the perpendicular and the central axis. The results show that the dose along the perpendicular becomes lower with the rising of distance to the steel shell, the dose beyond the perpendicular appears anisotropy and the impact of steel shell on the calculation of dose can be ignored. (authors)