Spatial fractionation of the dose in proton therapy: Proton minibeam radiation therapy.

In radiation therapy, a renewed interest is emerging for the study of spatially fractionated irradiation. In this article, a few applications using spatial fractionation of the dose will be discussed with a focus on proton minibeam radiation therapy. Examples of calculated dose (1D profiles and 2D dose distributions) and biological evidence obtained so far will be presented for various spatially fractionated techniques GRID, micro- and minibeam radiation therapy. Recent results demonstrating that proton minibeam radiation therapy leads to an increase in normal tissues sparing will be discussed, which opens the door to a dose escalation in the tumour and a possibly efficient treatment of very radioresistant tumours.