Impact of implanted metal plates on radiation dose distribution in vivo / 中华放射肿瘤学杂志

ABSTRACT

Objective To investigate the impact of metal plate on radiation dose distribution in surrounding tissues in cadaver specimens.Methods Stainless steel plate, titanium plate, and muscle strip were implanted into the left thigh of a corpse, respectively.All the specimens were irradiated with 6 MV X-ray , SSD = 100 cm.The absorbed dose of surface was measured by thermoluminiscent elements.Results Surface dose distributions differed significantly among the three different materials (F = 57.35, P < 0.01),with the amounts of 1.18 Gy ± 0.04 Gy (stainless steel plate), 1.12 Gy ± 0.04 Gy (titanium plate) and 0.97 Gy ±0.03 Gy (muscle strip), respectively.The surface absorbed doses on incident plane of stainless steel plate and titanium plate were significantly increased by 21.65% and 15.46% respectively as compared with that of muscle strip.The absorbed doses on the exit surface of stainless steel plate, titanium plate and muscle strip were 0.87 Gy ± 0.03 Gy, 0.90 Gy ± 0.02 Gy and 0.95 Gy ± 0.04 Gy, respectively (F =13.37, P <0.01).The doses on the exit surface of stainless steel plate and titanium plate were significantly lowered by 8.42% and 5.26% when compared with that of muscle strip.Using treatment planning system,the differences between dose distribution with and without metal plate were compared.Within 1 cm away from the incident plate, there was an obvious increase in the absorbed dose, while the influence was less than 5% 1cm outside the surface.The effect of dose distribution on exit surface was less than 2%.Conclusions The influence of metal plate on the radiotherapy dose distribution is significant.The deviations ranges from 5% to 29%.Under the same condition, the impact of stainless steel plate is much more than that of titanium alloy plate.