定位放射線照射の線量分布の検討 : 直線加速装置とgamma unitの比較

抄録

Currently used stereotactic irradiation techniques that employ high-energy photon beams are based either on agamma unit that uses stationary 201-cobalt beams or on isocentric linear accelerators. The techniques that rely on linear accelerators are divided into multiple non-coplanar converging arcs, precessional convergent irradiation, and others. These techniques have respective physical characteristics, for example, the precision of dose convergence and isodose distributions. We discuss the physical characteristics of the gamma unit, multiple non-coplanar converging arcs, and precessional convergent irradiation. In terms of the precision of dose convergence, the best was the gamma unit, followed by precessional convergent irradiation, with multiple non-coplanar converging arcs third. The precision of dose convergence deteriorated with diminishing field size in all techniques, and the precision of dose convergence was improved using a circular field with supplementary collimator among the techniques using linear accelerators. In addition, stereotactic irradiation techniques should be examined for disease treatment and running cost, because the techniques that have the greatest precision in dose convergence are incompatible with all-purpose usage.