biostudies-literatureFrick SDeutsche ForschungsgemeinschaftEuropean UnionEberhard Karls Universität Tübingen100561https://www.ebi.ac.uk/biostudies/studies/S-EPMC10924196biostudies-literatureUnknown29<h4>Background and purpose</h4>For dosimetry in magnetic resonance (MR) guided radiotherapy, assessing the magnetic field correction factors of air-vented ionization chambers is crucial. Novel MR-optimized chambers reduce MR-imaging artefacts, enhancing their quality assurance utility. This study aimed to characterize two new MR-optimized ionization chambers with sensitive volumes of 0.07 and 0.016 cm³ regarding magnetic field correction factors and intra-type variation and compare them to their conventional counterparts.<h4>Material and methods</h4>Five chambers of each type were evaluated in a water phantom, using a clinical linear accelerator and an electromagnet, as well as a 1.5 T MR-linac system. The magnetic field correction factor kB→,Q, addressing the change of responsePhysics and imaging in radiation oncologyExperimental characterization of four ionization chamber types in magnetic fields including intra-type variation.PMC10924196ZI 736/2-119NRM01 MRgRT-DOSThorwarth DKapsch RPFrick SSchneider MfalseExperimental characterization of four ionization chamber types in magnetic fields including intra-type variation.<h4>Background and purpose</h4>For dosimetry in magnetic resonance (MR) guided radiotherapy, assessing the magnetic field correction factors of air-vented ionization chambers is crucial. Novel MR-optimized chambers reduce MR-imaging artefacts, enhancing their quality assurance utility. This study aimed to characterize two new MR-optimized ionization chambers with sensitive volumes of 0.07 and 0.016 cm³ regarding magnetic field correction factors and intra-type variation and compare them to their conventional counterparts.<h4>Material and methods</h4>Five chambers of each type were evaluated in a water phantom, using a clinical linear accelerator and an electromagnet, as well as a 1.5 T MR-linac system. The magnetic field correction factor kB→,Q, addressing the change of response2024-01-01T00:00:00Z2024 Jan2026-07-15T01:19:23.483Z2025-04-06T01:41:02.349ZS-EPMC109241963846321810.1016/j.phro.2024.100561