Technical Note: Response measurement for select radiation detectors in magnetic fields

Med Phys. 2015 Jun;42(6):2837-40. doi: 10.1118/1.4919681.


Purpose: Dose response to applied magnetic fields for ion chambers and solid state detectors has been investigated previously for the anticipated use in linear accelerator-magnetic resonance devices. In this investigation, the authors present the measured response of selected radiation detectors when the magnetic field is applied in the same direction as the radiation beam, i.e., a longitudinal magnetic field, to verify previous simulation only data.

Methods: The dose response of a PR06C ion chamber, PTW60003 diamond detector, and IBA PFD diode detector is measured in a longitudinal magnetic field. The detectors are irradiated with buildup caps and their long axes either parallel or perpendicular to the incident photon beam. In each case, the magnetic field dose response is reported as the ratio of detector signals with to that without an applied longitudinal magnetic field. The magnetic field dose response for each unique orientation as a function of magnetic field strength was then compared to the previous simulation only studies.

Results: The measured dose response of each detector in longitudinal magnetic fields shows no discernable response up to near 0.21 T. This result was expected and matches the previously published simulation only results, showing no appreciable dose response with magnetic field.

Conclusions: Low field longitudinal magnetic fields have been shown to have little or no effect on the dose response of the detectors investigated and further lend credibility to previous simulation only studies.

MeSH terms

  • Magnetic Fields*
  • Monte Carlo Method
  • Particle Accelerators
  • Radiometry / instrumentation*