Impact of hip prosthesis on dose distribution of pelvic radiotherapy / 中华放射肿瘤学杂志

ABSTRACT

Objective To study the scattering effect of Co-Cr-Mo hip prosthesis which was high Z material for patients undergoing pelvic irradiation.Methods The hip prosthesis was set in water phantom (30 cm×30 cm×30 cm), determing points were chosen on the entrance side of both 6 MV and 10 MV beams at the distance of 0.5 cm, 1.0 cm, 2.0 cm to the hip prosthesis, and also on the exit side of both 6 MV and 10 MV beams at the distance of 3.0 cm, 5.0 cm, 7.0 cm to the hip prostheses.Dose behind the hip prosthesis at depths of 5.0 cm and 10.0 cm for 6 MV and 10 MV beams are also measured.ResultsThe dose deviation on the beams′ entrance side is between 0 to 5.0%, the backscatter effect was more obviously with the higher energy beam.The dose deviation on the beams′ exit side was between 21.6%-30.8%.With the same field size and depth, dose deviation becomes smaller when the beam energy was higher;while with the same energy and depth, dose deviation becomes smaller when the field size was bigger.Dose profiles behind the head of the hip prosthesis indicate obvious attenuation of the beam.Conclusions Beam arrangements that avoid the prosthesis should be considered first or we should at least reduce the weight of the beam that pass through the prosthesis.