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Title: Characterization of a new MOSFET detector configuration for in vivo skin dosimetry

Abstract

The dose released to the patient skin during a radiotherapy treatment is important when the skin is an organ at risk, or on the contrary, is included in the target volume. Since most treatment planning programs do not predict dose within several millimeters of the body surface, it is important to have a method to verify the skin dose for the patient who is undergoing radiotherapy. A special type of metal oxide semiconductors field-effect transistors (MOSFET) was developed to perform in vivo skin dosimetry for radiotherapy treatments. Water-equivalent depth (WED), both manufacturing and sensor reproducibility, dependence on both field size and angulation of the sensor were investigated using 6 MV photon beams. Patient skin dosimetries were performed during 6 MV total body irradiations (TBI). The resulting WEDs ranged from 0.04 and 0.15 mm (0.09 mm on average). The reproducibility of the sensor response, for doses of 50 cGy, was within {+-}2% (maximum deviation) and improves with increasing sensitivity or dose level. As to the manufacturing reproducibility, it was found to be {+-}0.055 mm. No WED dependence on the field size was verified, but possible variations of this quantity with the field size could be hidden by the assessment uncertainty. Themore » angular dependence, for both phantom-surface and in-air setups, when referred to the mean response, is within {+-}27% until 80 deg. rotations. The results of the performed patient skin dosimetries showed that, normally, our TBI setup was suitable to give skin the prescribed dose, but, for some cases, interventions were necessary: as a consequence the TBI setup was corrected. The water-equivalent depth is, on average, less than the thinnest thermoluminescent dosimeters (TLD). In addition, when compared with TLDs, the skin MOSFETs have significant advantages, like immediate both readout and reuse, as well as the permanent storage of dose. These sensors are also waterproof. The in vivo dosimetries performed prove the importance of verifying the dose to the skin of the patient undergoing radiotherapy.« less

Authors:
; ;  [1]
  1. Department of Medical Physics, San Bortolo Hospital, Vicenza (Italy)
Publication Date:
OSTI Identifier:
20726057
Resource Type:
Journal Article
Journal Name:
Medical Physics
Additional Journal Information:
Journal Volume: 32; Journal Issue: 6; Other Information: DOI: 10.1118/1.1924328; (c) 2005 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0094-2405
Country of Publication:
United States
Language:
English
Subject:
61 RADIATION PROTECTION AND DOSIMETRY; DOSIMETRY; IN VIVO; MOSFET; PATIENTS; PHANTOMS; PHOTON BEAMS; RADIATION DOSES; RADIOTHERAPY; SEMICONDUCTOR MATERIALS; SENSITIVITY; SKIN; THERMOLUMINESCENT DOSEMETERS

Citation Formats

Scalchi, Paolo, Francescon, Paolo, and Rajaguru, Priyadarshini. Characterization of a new MOSFET detector configuration for in vivo skin dosimetry. United States: N. p., 2005. Web. doi:10.1118/1.1924328.
Scalchi, Paolo, Francescon, Paolo, & Rajaguru, Priyadarshini. Characterization of a new MOSFET detector configuration for in vivo skin dosimetry. United States. https://doi.org/10.1118/1.1924328
Scalchi, Paolo, Francescon, Paolo, and Rajaguru, Priyadarshini. 2005. "Characterization of a new MOSFET detector configuration for in vivo skin dosimetry". United States. https://doi.org/10.1118/1.1924328.
@article{osti_20726057,
title = {Characterization of a new MOSFET detector configuration for in vivo skin dosimetry},
author = {Scalchi, Paolo and Francescon, Paolo and Rajaguru, Priyadarshini},
abstractNote = {The dose released to the patient skin during a radiotherapy treatment is important when the skin is an organ at risk, or on the contrary, is included in the target volume. Since most treatment planning programs do not predict dose within several millimeters of the body surface, it is important to have a method to verify the skin dose for the patient who is undergoing radiotherapy. A special type of metal oxide semiconductors field-effect transistors (MOSFET) was developed to perform in vivo skin dosimetry for radiotherapy treatments. Water-equivalent depth (WED), both manufacturing and sensor reproducibility, dependence on both field size and angulation of the sensor were investigated using 6 MV photon beams. Patient skin dosimetries were performed during 6 MV total body irradiations (TBI). The resulting WEDs ranged from 0.04 and 0.15 mm (0.09 mm on average). The reproducibility of the sensor response, for doses of 50 cGy, was within {+-}2% (maximum deviation) and improves with increasing sensitivity or dose level. As to the manufacturing reproducibility, it was found to be {+-}0.055 mm. No WED dependence on the field size was verified, but possible variations of this quantity with the field size could be hidden by the assessment uncertainty. The angular dependence, for both phantom-surface and in-air setups, when referred to the mean response, is within {+-}27% until 80 deg. rotations. The results of the performed patient skin dosimetries showed that, normally, our TBI setup was suitable to give skin the prescribed dose, but, for some cases, interventions were necessary: as a consequence the TBI setup was corrected. The water-equivalent depth is, on average, less than the thinnest thermoluminescent dosimeters (TLD). In addition, when compared with TLDs, the skin MOSFETs have significant advantages, like immediate both readout and reuse, as well as the permanent storage of dose. These sensors are also waterproof. The in vivo dosimetries performed prove the importance of verifying the dose to the skin of the patient undergoing radiotherapy.},
doi = {10.1118/1.1924328},
url = {https://www.osti.gov/biblio/20726057}, journal = {Medical Physics},
issn = {0094-2405},
number = 6,
volume = 32,
place = {United States},
year = {Wed Jun 15 00:00:00 EDT 2005},
month = {Wed Jun 15 00:00:00 EDT 2005}
}