Studies on the attenuating properties of various materials used for protection in radiotherapy and their effect of on the dose distribution in rotational therapy

Abstract

Protection of vital organs within a radiation field is one of the major concepts in radiotherapy. Measurements of beam attenuation by materials commonly used for protection in radiotherapy, such as lead, cerrobend and brass, as well as by three new materials for radiation shielding, which are polymers filled with tungsten powder, were carried out. The results of measurements were compared with the results of simulations for the same experimental setup to verify some aspects of the in-house developed Monte Carlo Radiotherapy Simulator. The later was also used for simulation studies on the effect of cylindrical protectors on the dose distributions in the rotational radiotherapy. The experimental and simulated data were found to be in a good agreement with a RMS error not higher than 2.1%. The metal-polymer composites can rival the lead in the protection of vital organs if the density provided is high. The results of studies in rotational therapy have shown that a protector of high density and bigger diameter offers more extensive protection of the organ at risk. In the case of cylindrical protector, however, increase in diameter leads to an increase of the attenuated field width, which is not always desirable. So, the solution could be to use larger diameter protector, placed closer to the phantom. Use of nonhazardous material, such as tungsten powder filled polymer, is preferable as well as combination of two materials with the outer layer made of denser material may improve the protector performance.