### Abstract

The ability of a commercially available dual bias, dual MOSFET dosimetry system to measure therapeutic doses reproducibly throughout its vendor-defined dose-based lifetime has been evaluated by characterizing its sensitivity variation to integrated/cumulative doses from high-energy (6 and 15 MV) photon radiotherapy beams. The variation of sensitivity as a function of total integrated dose was studied for three different dose-per-fraction levels; namely, 50, 200, and 1200 cGy/fraction. In standard sensitivity mode (i.e., measurements involving dose-per-fraction levels ≥100 cGy), the response of the MOSFET system to identical irradiations increased with integrated dose for both energies investigated. Dose measurement reproducibility for the low (i.e., 50 cGy) dose fractions was within 2.1% (if the system was calibrated before each in-phantom measurement) and 3.1% [if the system was calibrated prior to first use, with no intermediate calibration(s)]. Similarly, dose measurement reproducibility was between 2.2% and 6.6% for the conventional (i.e., 200 cGy) dose fractions and between 1.8% and 7.9% for escalated (i.e., 1200 cGy) dose fractions. The results of this study suggest that, due to the progressively increasing sensitivity resulting from the dual-MOSFET design, frequent calibrations are required to achieve measurement accuracy of ≤3% (within one standard deviation).

Original language | English (US) |
---|---|

Pages (from-to) | 39-47 |

Number of pages | 9 |

Journal | Medical Physics |

Volume | 35 |

Issue number | 1 |

DOIs | |

State | Published - 2008 |

### Fingerprint

### Keywords

- Dose response
- MOSFET
- Radiation measurement

### ASJC Scopus subject areas

- Biophysics

### Cite this

*Medical Physics*,

*35*(1), 39-47. https://doi.org/10.1118/1.2815626

**MOSFET sensitivity dependence on integrated dose from high-energy photon beams.** / Tanyi, James; Krafft, Shane P.; Hagio, Tomoe; Fuss, Martin; Salter, Bill J.

Research output: Contribution to journal › Article

*Medical Physics*, vol. 35, no. 1, pp. 39-47. https://doi.org/10.1118/1.2815626

}

TY - JOUR

T1 - MOSFET sensitivity dependence on integrated dose from high-energy photon beams

AU - Tanyi, James

AU - Krafft, Shane P.

AU - Hagio, Tomoe

AU - Fuss, Martin

AU - Salter, Bill J.

PY - 2008

Y1 - 2008

N2 - The ability of a commercially available dual bias, dual MOSFET dosimetry system to measure therapeutic doses reproducibly throughout its vendor-defined dose-based lifetime has been evaluated by characterizing its sensitivity variation to integrated/cumulative doses from high-energy (6 and 15 MV) photon radiotherapy beams. The variation of sensitivity as a function of total integrated dose was studied for three different dose-per-fraction levels; namely, 50, 200, and 1200 cGy/fraction. In standard sensitivity mode (i.e., measurements involving dose-per-fraction levels ≥100 cGy), the response of the MOSFET system to identical irradiations increased with integrated dose for both energies investigated. Dose measurement reproducibility for the low (i.e., 50 cGy) dose fractions was within 2.1% (if the system was calibrated before each in-phantom measurement) and 3.1% [if the system was calibrated prior to first use, with no intermediate calibration(s)]. Similarly, dose measurement reproducibility was between 2.2% and 6.6% for the conventional (i.e., 200 cGy) dose fractions and between 1.8% and 7.9% for escalated (i.e., 1200 cGy) dose fractions. The results of this study suggest that, due to the progressively increasing sensitivity resulting from the dual-MOSFET design, frequent calibrations are required to achieve measurement accuracy of ≤3% (within one standard deviation).

AB - The ability of a commercially available dual bias, dual MOSFET dosimetry system to measure therapeutic doses reproducibly throughout its vendor-defined dose-based lifetime has been evaluated by characterizing its sensitivity variation to integrated/cumulative doses from high-energy (6 and 15 MV) photon radiotherapy beams. The variation of sensitivity as a function of total integrated dose was studied for three different dose-per-fraction levels; namely, 50, 200, and 1200 cGy/fraction. In standard sensitivity mode (i.e., measurements involving dose-per-fraction levels ≥100 cGy), the response of the MOSFET system to identical irradiations increased with integrated dose for both energies investigated. Dose measurement reproducibility for the low (i.e., 50 cGy) dose fractions was within 2.1% (if the system was calibrated before each in-phantom measurement) and 3.1% [if the system was calibrated prior to first use, with no intermediate calibration(s)]. Similarly, dose measurement reproducibility was between 2.2% and 6.6% for the conventional (i.e., 200 cGy) dose fractions and between 1.8% and 7.9% for escalated (i.e., 1200 cGy) dose fractions. The results of this study suggest that, due to the progressively increasing sensitivity resulting from the dual-MOSFET design, frequent calibrations are required to achieve measurement accuracy of ≤3% (within one standard deviation).

KW - Dose response

KW - MOSFET

KW - Radiation measurement

UR - http://www.scopus.com/inward/record.url?scp=37549071493&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=37549071493&partnerID=8YFLogxK

U2 - 10.1118/1.2815626

DO - 10.1118/1.2815626

M3 - Article

VL - 35

SP - 39

EP - 47

JO - Medical Physics

JF - Medical Physics

SN - 0094-2405

IS - 1

ER -