BOLUS MATERIAL WHICH CAN BE USED IN HIGH ENERGY CO-60 PHOTON BEAMS

In ICRU Report 24, bolus material used in radiation therapy is defined as "tissue equivalent material placed around the irradiated object to provide build-up or attenuation or extra scattering in the beam". For ease of use it also has to be tissue equivalent, it should be transparent to facilitate beam localisation, flexible enough to conform to the surface contours easily, be able to be shaped, unaffected by high dose levels, durable, non-toxic, non-flammable, not cause producing fungi and bacteria and finally be at a reasonable cost. The aim of this study is to make a bolus material that can be prepared easily in the department with a low cost. The bolus material is composed of gelatine, glycerin, water, ethyil alcohol and sodium azite. It meets most of the requirements mentioned above for bolus. The absorption of that mixture with different thicknesses was compared with the absorption of RW3 solid water phantom using ionization method in Co-60 beam. It was observed that the dose at 0.5, 1, 1.5 cm depth is 1.5-2 %lower than the dose in RW3 but the doses at deeper points don't change. It is concluded that it can be used as a bolus.

Keywords: bolus material, co-60