Published in the Green Journal, this study led by MGH aimed to quantify the clinical applicability of converted MR images as a substitute of CT for IMPT treatment of the prostate. Using MRCAT (Magnetic Resonance for Calculating ATtenuation), a Philips-developed technology which produces a synthetic CT image consisting of five HU from a specific set of MRI acquisitions, IMPT plans were generated on the MRCAT for each of ten patient.

The plans were then recomputed onto the nominal planning CT for each patient with robustness analyses performed. This study found that MRCAT plans and their recomputated CT plans showed excellent agreement, with dose perturbations due to setup shifts and range uncertainties well within clinical acceptance. This study concludes the clinical acceptability of substituting MR converted the relative proton stopping power ratio (RSP) images instead of CT for IMPT planning of prostate cancer. This further translates into higher contouring accuracy along with lesser imaging dose.