Chamber response in treatment-strength magnetic fields
In plain words
Machines that image with magnetic resonance while treating place the detector inside a strong magnet, which bends the electrons it is trying to count. The resulting response change is not fully predictable.
Precise statement
Determine the magnetic-field correction factor for ionization chambers and solid-state detectors in fields of 3.5 to 15 kG, as a function of chamber axis orientation relative to the magnetic field and beam, cavity dimensions and gas, to below 0.5 percent. Include the electron return effect at tissue and air interfaces. An answer is a validated correction factor set and a primary standard valid in field.
What would settle it
Water calorimetry in a magnetic field compared with chamber readings over the orientation range.
Status in the literature
Calorimetric primary standards in magnetic fields were demonstrated by the early 2020s; a complete formalism across detectors and orientations remains incomplete.