abstract
- The spatial dose-rate distribution arising from a unit activity point source of 194Ir embedded in an infinite water medium has been calculated. These results may prove to be both useful and timely; 194Ir is a beta-particle-emitting radionuclide that is a suitable candidate for radioimmunotherapy, and a means for producing it fairly easily has recently been made available. Calculation of the beta-ray dose-rate distribution is based on a new set of monoenergetic electron dose point kernels which are results from an improved Monte Carlo (ETRAN) calculation. The spatial dose-rate distribution for 32P was also calculated and compared with results from the EGS4-PRESTA and ACCEPT Monte Carlo codes. The ETRAN-based distribution agrees with that from EGS4-PRESTA to within 2% out to 3.6 mm from the source, a distance over which 90% of the source energy is deposited. The ETRAN-based distribution also agrees well with that from ACCEPT between 0.6 and 4 mm from the source; at distances < 0.6 mm, values from ACCEPT are about 6% larger than ones calculated here.