A quantitative study of MRI-based treatment planning for the percutaneous radiation therapy of brain tumors

This study examined to which extent treatment plans for brain tumors can be constructed with a commercial treatment planning system (TPS) based on MRI data only. CadPlan 6.4.7 was used as TPS. In particular, differences between MRT-based and conventional CT-based plans were examined systematically. The quantification of the retrospective evaluation was carried out by the point-wise dose difference and the gamma-distribution. In this study the gamma-distribution did not appear advantageous over the dose difference for the tolerance range (point-wise dose difference < 3%, distance criterion LLL 5 mm). The calculated dose distribution showed large differences (up to 103%) at the boundary of the treatment fields, in the regions of the head contour, and in areas with air inclusions and significant bone structures. The inner parts of the fields, and therefore the actual target volume, revealed only small deviations in the range of-2% in the homogeneous distribution.