Simulating the impact of iodine as a contrast substance to enhance radiation to the tumor in a brain x-ray phototherapy

Abstract

The influence of adding iodine as a contrast substance to elevate radiation in a tumor is studied using simulation techniques of Monte-Carlo. The study is carried on a brain cancer by adopting an unsophisticated head phantom. The ionizing radiation source is an external beam of x-rays with energy range of a few tens of keV. The expected radiation dose increment due to adding the iodine is investigated by comparing the radiation in the tumor after and before adding the iodine and calculating the ratio between the two doses. Several concentrations of the contrast substance are used to quantify its impact. The change of the dose increment with the source energy is also examined. It is found that the radiation elevation in the tumor tends to saturate with increasing the iodine concentration, and for the studied domain of energies (30 keV–100 keV), the radiation dose enhancement factors (RDEF) for the different iodine concentrations (1%–9%) show peaked curves, with the peak occurring between 60 keV and 70 keV. For the highest concentration studied, 9%, the peak value is almost 7.