@article{64d3dde71ae944c5b10498a9bf79da81,
title = "Implantable MOSFET detectors: Evaluation of a new design",
abstract = "The authors have studied the performance of a new version of the implantable MOSFET detector designed for clinical use. Detectors were irradiated under 6- and 18-MV beams in water at body temperature to the calibration dose of 200 cGy/fraction for 20 daily fractions to determine their response and reproducibility. Additional measurements were performed in a solid phantom under 6-MV irradiation at room temperature to daily doses of 100, 150, 200, 250, 400 and 600 cGy/fraction. Finally, the angular dependence with respect to rotation about the detector's longitudinal axis was studied. At body temperature, the detectors were found to have an average response within ±3% of the calibration dose with a standard deviation of 2% or less. At room temperature, doses lower than the calibration dose led to a slight overresponse while doses higher than the calibration dose led to a slight underresponse. Angular dependence was not significant, on average within 1.2% of the mean. When used as specified by the manufacturer, these detectors should provide data useful to verify the delivered dose for external beam radiation therapy within a certain tolerance.",
keywords = "Absolute dose measurements, In vivo dosimetry, MOSFET",
author = "Briere, {Tina Marie} and Gillin, {Michael T.} and Beddar, {A. Sam}",
note = "Funding Information: This work was partly supported by a sponsored research agreement with Sicel Technologies to study the DVS detector system (MDACC SRA 2006-0018226JW). The authors are grateful to Michael Riddle, Dr. Gloria Beyer, Greg Mann, and Connie Childress for their assistance and helpful discussions. TABLE I. Deviation from the calibration dose of 200 cGy/fraction for detectors irradiated under 6- and 18-MV photon beams. Detectors in the water phantom were held at 37 ° C and irradiated for 20 fractions, while those in a Virtual Water phantom were held at room temperature and irradiated for ten fractions. Average deviation ( % ) Standard deviation ( % ) Detector 1 Detector 2 Detector 1 Detector 2 Body temperature 6 × − 0.4 − 2.1 1.9 1.6 18 × − 3.0 1.3 1.7 2.0 Room temperature 6 × − 1.2 − 0.5 0.7 2.5 18 × 0.4 − 2.5 2.6 1.5 TABLE II. Deviation from the delivered dose for detectors irradiated under 6-MV photon beams. All detectors were irradiated in a Virtual Water phantom at room temperature for ten fractions. Average deviation ( % ) Standard deviation ( % ) Detector 1 Detector 2 Detector 1 Detector 2 100 cGy 1.7 2.6 4.2 2.4 150 cGy 3.1 3.6 2.9 0.9 250 cGy − 2.0 − 1.7 2.1 2.2 400 cGy − 2.7 − 1.7 3.9 2.6 600 cGy − 4.5 − 3.5 2.9 2.4 FIG. 1. (a) Comparison of the initial prototype detector (left) and the new commercial detector with a dual-transistor design (right). (b) Reader with rf wand and computer controller. (c) Virtual water phantom with positive inset for the detector shown in front. FIG. 2. Body temperature measurements at the calibration dose of 200 cGy. Deviation of the measured dose from the delivered dose for each treatment fraction. The detectors were irradiated once each day in a water phantom at a depth of 5 cm. FIG. 3. Room temperature measurements at the calibration dose of 200 cGy. Deviation of the measured dose from the delivered dose for each treatment fraction. The detectors were irradiated once each day in a Virtual Water phantom at a depth of 5 cm. FIG. 4. Room temperature measurements at doses outside the calibration dose. Deviation of the measured dose from the delivered dose for each treatment fraction. The detectors were irradiated once each day in a Virtual Water phantom at a depth of 5 cm. FIG. 5. Dependence on detector rotation about its long axis. Deviation of the measured dose from the average delivered dose. The detectors were irradiated once each day in a Virtual Water phantom at a depth of 5 cm. Two of the four detectors were rotated through the angles 0 ° , 90 ° , and 180 ° , while the other two were rotated through the angles 45 ° , 135 ° , and 225 ° . ",
year = "2007",
doi = "10.1118/1.2799578",
language = "English (US)",
volume = "34",
pages = "4585--4590",
journal = "Medical physics",
issn = "0094-2405",
publisher = "AAPM - American Association of Physicists in Medicine",
number = "12",
}