Congratulations on getting to a decision. This is a trial of "dose painting". In one arm, the dose painting will be done with moderately hypofractionated IMRT, in the other arm with extreme hypofractionation. If you want to read more about
dose painting, here's an article that mentions this trial:
Dose Painting: simultaneous integrated boost (SIB) to the dominant intraprostatic lesion (DIL)