Characterization of commercial MOSFET detectors and their feasibility for in-vivo HDR brachytherapy

Characterization of microMOSFET detectors for in vivo dosimetry in high‐dose‐rate brachytherapy with 192Ir

“…The most important dependence observed in our study was the angular dependence. In studies of similar detectors (TN502RD y TN1002RDH,RDI,RD), Pomije et al , Dong et al , Roshau and Hintenlang , Koivisto et al and Phurailatpam et al all used x‐ray devices of between 60 and 120 kVp, with HVL values ranging between 3.0 mmAl and 7.7 mmAl, except in the study by Pomije et al , which used a source of 192 Ir. Furthermore, the measurements were conducted in air, PMMA, and virtual water, and the increments in angle measurements ranged between π/36 radians and π/4 radians.…”

“…None of the aforementioned studies proposed the development of a mathematical model from the experimental data to allow correction for angular dependence, despite reporting mean values of up to 14.7% for measurements in air (maximum variation in angular sensitivity of 55%) and up to 9.7% for those in PMMA (maximum variation in angular sensitivity of 40%). Phurailatpam et al 16 used a virtual-water phantom and described a maximum difference in sensitivity of (9.9 AE 0.4)% (k = 1). Ramaseshan et al 12 performed measurements in a single plane [z = 0, Fig.…”

“…This study focused on TN‐502‐RDM MOSFET detectors, hereafter microMOSFETs, manufactured by Best Medical Canada, which were characterized in water for a 192 Ir source. Studies of similar MOSFET detectors have analyzed angular dependence using x‐ray diagnostic equipment (80 kV) for models TN‐1002‐RDH and TN‐502‐RDI or a solid‐water phantom for model TN‐502‐RD) . Previous investigations of the dependencies of the microMOSFET tested in our study used megavoltage energies (6 MV), other energies being considered just to analyze the energy dependence, and none of them used an 192 Ir source .…”

“…5 There is an increasing interest in metal oxide semiconductor field-effect transistors (MOSFETs), because they provide real-time measurements and are small enough to fit within the intraluminal catheters or needles used in HDRBT. However, their response can also be influenced by measurement conditions and it may be dependent on the temperature, detector-source distance, and relative orientation of detector and source (angular dependence) [11][12][13][14][15][16][17] These dependencies can be a major source of measurement uncertainty if not correctly managed.…”

“…Studies of similar MOSFET detectors have analyzed angular dependence using x-ray diagnostic equipment (80 kV) for models TN-1002-RDH and TN-502-RDI 11,15 or a solid-water phantom for model TN-502-RD). 16 Previous investigations of the dependencies of the microMOSFET tested in our study used megavoltage energies (6 MV), other energies being considered just to analyze the energy dependence, and none of them used an 192 Ir source. 12 Another group 17 only used two rotation axes to determine the angular dependence unlike the present study, which consider the three orthogonal planes.…”