Dosimetric evaluation of a MOSFET detector for clinical application in photon therapy

Kohno, Ryosuke; Hirano, Eriko; Nishio, Teiji; Miyagishi, Tomoko; Goka, Tomonori; Kawashima, Mitsuhiko; Ogino, Takashi

doi:10.1007/s12194-007-0007-9

Cited by 16 publications

(10 citation statements)

References 14 publications

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“…The response of MOSFET detectors is dependent on the angle of incidence. (1)(2)(3)(4)(5)7) The angular dependence was experimentally evaluated using a cylindrical acrylic phantom with a radius of 8 cm and a length of 15 cm. The angular response with respect to the cable axis was measured at 30°, 45°, 60°, 90°, 120°, 135°, 150°, and 180°.…”

Section: B3 Angular Dependencementioning

confidence: 99%

Proton dose distribution measurements using a MOSFET detector with a simple dose‐weighted correction method for LET effects

Kohno

Hotta

Matsuura

et al. 2011

J Applied Clin Med Phys

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We experimentally evaluated the proton beam dose reproducibility, sensitivity, angular dependence and depth‐dose relationships for a new Metal Oxide Semiconductor Field Effect Transistor (MOSFET) detector. The detector was fabricated with a thinner oxide layer and was operated at high‐bias voltages. In order to accurately measure dose distributions, we developed a practical method for correcting the MOSFET response to proton beams. The detector was tested by examining lateral dose profiles formed by protons passing through an L‐shaped bolus. The dose reproducibility, angular dependence and depth‐dose response were evaluated using a 190 MeV proton beam. Depth‐output curves produced using the MOSFET detectors were compared with results obtained using an ionization chamber (IC). Since accurate measurements of proton dose distribution require correction for LET effects, we developed a simple dose‐weighted correction method. The correction factors were determined as a function of proton penetration depth, or residual range. The residual proton range at each measurement point was calculated using the pencil beam algorithm. Lateral measurements in a phantom were obtained for pristine and SOBP beams. The reproducibility of the MOSFET detector was within 2%, and the angular dependence was less than 9%. The detector exhibited a good response at the Bragg peak (0.74 relative to the IC detector). For dose distributions resulting from protons passing through an L‐shaped bolus, the corrected MOSFET dose agreed well with the IC results. Absolute proton dosimetry can be performed using MOSFET detectors to a precision of about 3% (1 sigma). A thinner oxide layer thickness improved the LET in proton dosimetry. By employing correction methods for LET dependence, it is possible to measure absolute proton dose using MOSFET detectors.PACS number: 87.56.‐v

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Section: B3 Angular Dependencementioning

confidence: 99%

Proton dose distribution measurements using a MOSFET detector with a simple dose‐weighted correction method for LET effects

Kohno

Hotta

Matsuura

et al. 2011

J Applied Clin Med Phys

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“…All measurement points were set in the center of an exposed square area. We used a beam angle of 0°for all of the experiments, thus avoiding uncertainties (*2%) of angular dependence [7,11] of the MOSFET detector in the dose measurements, and unnecessary complexities in the SP dose calculations. We estimated the reproducibility as ±1.5% (1 standard deviation) for five consecutive irradiations of 100 MU each.…”

Section: Experimental Apparatusmentioning

confidence: 99%

“…Our dose measurements were performed at a beam angle of 0°. Given the variety of beam angles used in actual radiotherapy, the ±2% angular dependence of the MOS-FET detector must be considered [7,11]. The angular dependence may lead to a decrease in accuracy at some angles, which, in turn, may affect the clinical utility of this detector.…”

Section: Dose Calculation and Data Analysismentioning

confidence: 99%

“…The detector which we used is a dual-MOSFET detector consisting of two identical MOSFETs fabricated on the same silicon chip and operating at two different gate bias voltages, allowing temperature compensation of the detector response [5]. The MOSFET detector has been widely used for measuring radiation doses [6][7][8][9][10][11], and the accuracy, reliability, and usefulness of the MOSFET detector in clinical applications such as pinpoint absolute dosimetry has been reported [12].…”

Section: Introductionmentioning

confidence: 99%

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Evaluation of the usefulness of a MOSFET detector in an anthropomorphic phantom for 6-MV photon beam

Kohno

Hirano

Kitou

et al. 2010

Radiol Phys Technol

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In order to evaluate the usefulness of a metal oxide-silicon field-effect transistor (MOSFET) detector as a in vivo dosimeter, we performed in vivo dosimetry using the MOSFET detector with an anthropomorphic phantom. We used the RANDO phantom as an anthropomorphic phantom, and dose measurements were carried out in the abdominal, thoracic, and head and neck regions for simple square field sizes of 10 x 10, 5 x 5, and 3 x 3 cm(2) with a 6-MV photon beam. The dose measured by the MOSFET detector was verified by the dose calculations of the superposition (SP) algorithm in the XiO radiotherapy treatment-planning system. In most cases, the measured doses agreed with the results of the SP algorithm within +/-3%. Our results demonstrated the utility of the MOSFET detector for in vivo dosimetry even in the presence of clinical tissue inhomogeneities.

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“…Metal-oxide semiconductor field effect transistor (MOSFET) dosimeters are widely used for measuring exposure dose in radiation therapy, which uses high X-ray energies [7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Evaluating the performance of a MOSFET dosimeter at diagnostic X-ray energies for interventional radiology

Chida

Inaba

Masuyama

et al. 2009

Radiol Phys Technol

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For reducing the risk of skin injury during interventional radiology (IR) procedures, it has been suggested that physicians track patients' exposure doses. The metal-oxide semiconductor field effect transistor (MOSFET) dosimeter is designed to measure patient exposure dose during radiotherapy applications at megavoltage photon energies. Our purpose in this study was to evaluate the feasibility of using a MOSFET dosimeter (OneDose system) to measure patients' skin dose during exposure to diagnostic X-ray energies used in IR. The response of the OneDose system was almost constant at diagnostic X-ray energies, although the sensitivity was higher than that at megavoltage photon energies. We found that the angular dependence was minimal at diagnostic X-ray energies. The OneDose is almost invisible on X-ray images at diagnostic energies. Furthermore, the OneDose is easy to handle. The OneDose sensor performs well at diagnostic X-ray energies, although real-time measurements are not feasible. Thus, the OneDose system may prove useful in measuring patient exposure dose during IR.

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Dosimetric evaluation of a MOSFET detector for clinical application in photon therapy

Cited by 16 publications

References 14 publications

Proton dose distribution measurements using a MOSFET detector with a simple dose‐weighted correction method for LET effects

Proton dose distribution measurements using a MOSFET detector with a simple dose‐weighted correction method for LET effects

Evaluation of the usefulness of a MOSFET detector in an anthropomorphic phantom for 6-MV photon beam

Evaluating the performance of a MOSFET dosimeter at diagnostic X-ray energies for interventional radiology

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