Beam Monitor Calibration for Pencil Beam Scanning Delivery in Terms of the Number of Protons and Light Ions Per Spot

This publication supplements IAEA Technical Reports Series 398 Rev. 1 (IAEA TRS-398 Rev 1), published in 2024, which provides guidance on the determination of absorbed dose to water for proton and light ion beams under reference conditions for both broad-beam and pencil-beam scanning delivery systems. For pencil-beam scanning systems, this supplement presents practical methods and procedures for calibrating beam monitors in terms of the number of protons and light ions per spot, a topic that falls outside the scope of IAEA TRS-398 Rev 1. This calibration constitutes an essential step in the dosimetric commissioning of proton and light-ion therapy facilities and is subsequently monitored on a routine basis. Drawing on key research and data from proton and light-ion therapy facilities across IAEA Member States, this publication provides important guidance for professionals working in this field.