Dose response of selected solid state detectors in applied homogeneous transverse and longitudinal magnetic fields

Abstract

When transverse magnetic fields are present, great care must be taken when using diamond or diode detectors. Dose response varies with relative detector orientation, magnetic field strength, and between detectors. This response can be considerable (∼20% for both detectors). Both detectors in longitudinal fields exhibit little to no dose response as a function of magnetic field. Water tank simulations seem to suggest that the diode detector is better suited to general beam commissioning, and each detector must be investigated separately.

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

“…The longitudinal field dose response of the PR06C farmer chamber, 4 PTW60003 diamond detector, 5 and IBA PFD diode detector 5 is verified experimentally in this work, details on the physical properties of these three detectors can be found in Table I. Each detector was irradiated in air with a tight fit buildup cap to ensure electronic equilibrium; the buildup caps used are noted in Table I and were either a 1.3 cm PMMA F.…”

“…Each figure contains both the orientation III and IV measurements at low field longitudinal magnetic fields and previously published simulation data of these detectors in orientations III and IV. 4,5 The standard deviation in the simulation data sets was 0.25%, 0.7%, and 0.9% for the PR06C, PTW60003, and IBA PFD, respectively, while the estimated error in the measurements was ∼0.1%-∼0.2% for all three detectors. Both the measurements as well as the simulated ratio of the detectors' response with and without magnetic field applied during irradiation are close to 1.0.…”

A GPU‐accelerated Monte Carlo dose calculation platform and its application toward validating an MRI‐guided radiation therapy beam model

“…In the clinic, g should be applicable to nearly any application requiring high dose accuracy, such as beam modeling, 21 IMRT optimization, 42 dosimeter response modeling, 28,43 dose validation, 19 dose accumulation, 44 among others. As an example, due to the three-source nature of the MRIdian system, quasi-3D dosimeters, such as ArcCHECK (Sun Nuclear Corp., Melbourne, FL), are quite useful for dosimetry measurements.…”

“…[23][24][25][26][27][28] Its kernel (version 2006) is relatively compact including roughly 3000 lines of  code. The code is well-documented with extensive detail on the theory underlying all scattering processes, thus readily enabling its adaptation on a GPU, namely, our implementation g presented in this work.…”

Dosimetry in the presence of strong magnetic fields

“…As a result, there is great interest in developing new external-beam radiotherapy machines with integrated MRI [3][4][5][6][7]. However, since MRI requires magnetic (B) fields, the Lorentz force influences the trajectories of the secondary electrons, which in turn affects both the dose distribution in water [1,8,9] and the dose-response of ionization chambers [6,[10][11][12] and several other detectors [13,14]. Thus, dosimetry in the presence of a B-field requires understanding both the B-field effects on the dose distribution and the response of detectors.…”