Surface dosimetry in a CT scanner using MOSFET detectors and Monte Carlo simulations

Verhaegen, Frank; Lemire, Martine; Hallil, A; Hegyi, György

doi:10.1088/1742-6596/102/1/012026

Cited by 7 publications

(4 citation statements)

References 8 publications

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“…MOSFETs have unique advantages as dosimeters in that they are small in size, simple to use, and provide immediate dose measurement. MOSFETs can be used for patient surface CT dosimetry, 1,2 or more commonly, with anthropomorphic phantoms for the measurement of organ dosimetry [3][4][5][6][7] and projection of radiation risk for a given CT examination. 3,4 This is of particular significance for pediatric diagnostic examinations, given the higher radiosensitivity of children, which is of particular interest at our institution.…”

Section: Introductionmentioning

confidence: 99%

“…Despite the increased use of MOSFET detectors for CT dosimetry, no standard calibration methodology has been identified nor expected calibration uncertainty quantified. The purpose of this investigation was to (1) compare MOS-FET calibration techniques found in the literature to determine equivalence or difference of calibration coefficient magnitude and precision; (2) determine greatest achievable calibration precision as a function of detector exposure and determine which detector exposure level provides the maximum benefit of calibration precision versus loss of lifetime dosimetry capacity; (3) finally, determine if waiting 5 min versus 0 min for signal equilibration has any effect on calibration precision and accuracy.…”

Section: Introductionmentioning

confidence: 99%

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Establishing a standard calibration methodology for MOSFET detectors in computed tomography dosimetry

Brady

Kaufman

2012

Medical Physics

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The best measured calibration precision was obtained by exposing the MOSFET detectors to 23 mGy. No signal equilibration time is necessary to improve calibration precision. A significant difference between calibration outcomes was demonstrated for FIA with CT compared to the other two methodologies. If the FIA with a CT calibration methodology was used to create calibration coefficients for the eventual use for phantom dosimetry, a measurement error ~12% will be reflected in the dosimetry results. The calibration process must emulate the eventual CT dosimetry process by matching or excluding scatter when calibrating the MOSFETs. Finally, the authors recommend that the MOSFETs are energy calibrated approximately every 2500-3000 mV.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Establishing a standard calibration methodology for MOSFET detectors in computed tomography dosimetry

Brady

Kaufman

2012

Medical Physics

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“…MOSFETs have been used to assess surface dose (Verhaegen et al 2008) or, in an anthropomorphic phantom, to assess organ dose (Jones et al 2005, Yoshizumi et al 2007, Hurwitz et al 2007a, 2007b and to project radiation risk (Hurwitz et al 2007a(Hurwitz et al , 2007b In vivo skin dosimetry requires a dosimeter with a reproducible WED, close to the 7 mg cm −2 23 recommended by the ICRP (1992). The advantage of MOSFETs for skin dosimetry was demonstrated by Butson et al (1996), who used bare n-type MOSFETs, without any build up above the gate, placed in a phantom holder using wax to fill air cavities.…”

Section: Applicationsmentioning

confidence: 99%

Semiconductor dosimetry in modern external-beam radiation therapy

et al. 2020

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Semiconductor dosimeters are ubiquitous in modern external-beam radiation therapy. They possess key features. The response, electronically available in real time, is stable and linear with absorbed dose for given irradiation conditions; the radiation-sensitive volume can be rather small in size, while retaining mechanical strength and high sensitivity. We describe three common semiconductor dosimeters: diodes, metal-oxide-semiconductor field-effect transistors and diamonds. We discuss in detail their operation principles and applications in modern external-beam radiation therapy, primarily with megavoltage photon beams. We also explore their use in proton and heavy ion therapy, and in experimental radiotherapy techniques such as synchrotron-based micro-beam radiation therapy.

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“…Measurement of surface dose portrays a greater technical challenge since the distance to the superficial layer is small. MOSFET with a very small size and ease of use make them excellent candidates for clinical patient measurements [2]. The dose to the surface mainly depends on the field size, source to skin distance (SSD), beam energy, beam angle, and beam modifiers such as multileaf collimator (MLC), block systems, and types of beam used to treat the tumor [3][4][5].…”

Section: Introductionmentioning

confidence: 99%

Surface Radiation Dose Measurement with Mosfet for Head and Neck Cancer using Phantom

Mishra¹

2021

CTOIJ

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Aim:The focus of this study was on the surface dose received by the patients during radiation treatment.1.2.Materials & Method: MOSFET ("Metal-Oxide-Semiconductor Field-Effect Transistor") detector due to its small size and greater reproducibility and sensitivity was used. Calibration of MOSFET was done to check for its accuracy and linearity along with field size dependence, dose-rate dependence, and angular dependence. Patient plans with Head & Neck cancer were taken and loaded onto the MOSFET. VMAT ("Volumetric-Modulated Arc Therapy") and 3DCRT ("3-Dimensional Computed Radiation Therapy") both techniques plans were taken.Result: Angular, field size, and dose-rate dependence was found to be ±1%, ±2.76%, and ±1.64% respectively. Conclusion:The measured values from MOSFET agreed with TPS (Treatment Planning System) calculated values for surface dose with 95% confidence.

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Surface dosimetry in a CT scanner using MOSFET detectors and Monte Carlo simulations

Cited by 7 publications

References 8 publications

Establishing a standard calibration methodology for MOSFET detectors in computed tomography dosimetry

Establishing a standard calibration methodology for MOSFET detectors in computed tomography dosimetry

Semiconductor dosimetry in modern external-beam radiation therapy

Surface Radiation Dose Measurement with Mosfet for Head and Neck Cancer using Phantom

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