Figure 1.

Illustration of an image-guided adaptive workflow, where proton treatment plans are optimized on the reference SPR values (here called RSP, (A, D) and then recalculated on the SPR reconstructed from a low-dose pCT image (B, E, 1% of the full fluence) and from the proposed fluence-modulated approach (C, F), which restores approximately the same SPR quality as the reference image in the patient anatomy traversed by the beam, while reducing the fluence to 1% in less relevant anatomical regions. The corresponding dose–volume histograms are in the right column, showing equivalent dosimetric performances of the fluence modulated approach as the reference SPR. Figure from Dedes et al^{32 ©} Institute of Physics and Engineering in Medicine. Reproduced by permission of IOP Publishing. All rights reserved. SPR, stopping power ratio