An investigation on the dosimetric impact of hip prosthesis in radiotherapy

The objectives of this study are to evaluate the dosimetric impact of hip prosthesis using ELEKTA linac X-rays and compare the dose perturbations of metallic and nonmetallic hip prostheses. The local dose distributions of typical hip prostheses were calculated for 4, 8, and 15 MV beams by Geant4. Three prosthesis materials were selected in calculation to reveal the relation between material type and local dose perturbations of prostheses. Furthermore, the effect of nominal energy on prosthesis perturbation was also discussed and analyzed. Taking the calculated dose to the hip joint as reference, considerable differences were observed between prostheses and hip joints. In the pros- thesis shadow region, the relative dose decreasing was up to 36, 21, and 16 % for the Co-Cr-Mo alloy, titanium alloy, and ceramic prostheses, respectively. In backscat- tering region, the relative dose increasing was about 1-7 %. Overall, the results show that the dose perturbation effect of prostheses was mainly determined by material type, nominal energy, and density. Among these typical hip prostheses, ceramic prosthesis introduces the lowest dose perturbations.