Abstract
PROPOSE: Carbon ion therapy is indicated for cases in which stents have been inserted, such as bile ducts, but the effect of metal stents on carbon ion therapy is unclear. In this study, the dose perturbation of carbon ion therapy caused by metallic bile duct stents was evaluated by dosimetry. MATERIALS AND METHODS: Five different types of metal stents (EGIS Double Bear Biliary Stent, EGIS Single Bear Covered Biliary Stent, BileRush Selective, Niti-S Less Shortening D-type Stent, and ZEO Stent V) were placed between solid phantoms and Gafchromic film were placed around the stents and at each depth. The phantom was irradiated with a Carbon ion Beam to form a 5 cm × 5 cm × 5 cm spread-out Brag peak. The dose change due to the stent was evaluated by comparing the film values of similar irradiations without the stent in place. RESULT: The results showed that the dose perturbation with and without the stent was <10%. A dose reduction area along the shape of the stent appeared at the end of the irradiation field. CONCLUSION: The effect of metal stents on the carbon dose distribution was assumed to be comparable to that of x-rays and protons.