Fig. 1From: Proton and helium ion radiotherapy for meningioma tumors: a Monte Carlo-based treatment planning comparisonThe four panels (a-d) display the complex relation between the contoured PTV and OARs for the four considered patient cases on the X-ray computed tomography axial images (gray scale), with overlaid dose distributions (color wash) for proton plans of fixed RBE calculated with MCTP. Second beam for patient B (panel b) is following the head-feet axisBack to article page