The aim of this work package is to perform comprehensive measurements of proton beam characteristics and detector properties in the presence of magnetic fields for the purpose of a traceable method for dosimetry in MRgPT facilities.

Dose measurements on scanned and scattered proton beams will be performed in the magnetic field of a commercial MRI scanner. Based on the developed measurement methodology, the determination of correction factors and the measurements in relevant proton fields it will be investigated whether a traceable dose measurement method for MRgPT can be established using the concepts of IAEA TRS-483 (see WP 1).

Necessary data, recommendations, procedures and definitions for mapping the magnetic field of the facility will be provided. The suitability of detectors and phantoms will be identified, and the measurement setup will be established for dose measurements in scanned pencil beam proton fields in the presence of magnetic fields. Measurements will be performed with the aim to derive correction factors for ionization chambers for dosimetry in MRgPT facilities.