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Title: A real-time in vivo dosimetric verification method for high-dose rate intracavitary brachytherapy of nasopharyngeal carcinoma

Abstract

Purpose: A real-time in vivo dosimetric verification method using metal-oxide-semiconductor field effect transistor (MOSFET) dosimeters has been developed for patient dosimetry in high-dose rate (HDR) intracavitary brachytherapy of nasopharyngeal carcinoma (NPC). Methods: The necessary calibration and correction factors for MOSFET measurements in {sup 192}Iridium source were determined in a water phantom. With the detector placed inside a custom-made nasopharyngeal applicator, the actual dose delivered to the tumor was measured in vivo and compared to the calculated values using a commercial brachytherapy planning system. Results: Five MOSFETs were independently calibrated with the HDR source, yielding calibration factors of 0.48 {+-} 0.007 cGy/mV. The maximum sensitivity variation was no more than 7% in the clinically relevant distance range of 1-5 cm from the source. A total of 70 in vivo measurements in 11 NPC patients demonstrated good agreement with the treatment planning. The mean differences between the planned and the actually delivered dose within a single treatment fraction were -0.1%{+-} 3.8% and -0.1%{+-} 3.7%, respectively, for right and left side assessments. The maximum dose deviation was less than 8.5%. Conclusions: In vivo measurement using the real-time MOSFET dosimetry system is possible to evaluate the actual dose to the tumor received by themore » patient during a treatment fraction and thus can offer another line of security to detect and prevent large errors.« less

Authors:
; ; ; ; ;  [1];  [2];  [3]
  1. State Key Laboratory of Oncology in South China, Sun Yat-sen University Cancer Center, Guangzhou 510060 (China) and Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW 2522 (Australia)
  2. (China)
  3. (Australia)
Publication Date:
OSTI Identifier:
22099079
Resource Type:
Journal Article
Journal Name:
Medical Physics
Additional Journal Information:
Journal Volume: 39; Journal Issue: 11; Other Information: (c) 2012 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; 62 RADIOLOGY AND NUCLEAR MEDICINE; 46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; 60 APPLIED LIFE SCIENCES; BRACHYTHERAPY; CALIBRATION; CARCINOMAS; DOSE RATES; DOSIMETRY; IN VIVO; MOSFET; PATIENTS; PHANTOMS; PLANNING; QUALITY ASSURANCE; RADIATION DOSES; VERIFICATION

Citation Formats

Qi Zhenyu, Deng Xiaowu, Cao Xinping, Huang Shaomin, Lerch, Michael, Rosenfeld, Anatoly, State Key Laboratory of Oncology in South China, Sun Yat-sen University Cancer Center, Guangzhou 510060, and Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW 2522. A real-time in vivo dosimetric verification method for high-dose rate intracavitary brachytherapy of nasopharyngeal carcinoma. United States: N. p., 2012. Web. doi:10.1118/1.4758067.
Qi Zhenyu, Deng Xiaowu, Cao Xinping, Huang Shaomin, Lerch, Michael, Rosenfeld, Anatoly, State Key Laboratory of Oncology in South China, Sun Yat-sen University Cancer Center, Guangzhou 510060, & Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW 2522. A real-time in vivo dosimetric verification method for high-dose rate intracavitary brachytherapy of nasopharyngeal carcinoma. United States. doi:10.1118/1.4758067.
Qi Zhenyu, Deng Xiaowu, Cao Xinping, Huang Shaomin, Lerch, Michael, Rosenfeld, Anatoly, State Key Laboratory of Oncology in South China, Sun Yat-sen University Cancer Center, Guangzhou 510060, and Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW 2522. Thu . "A real-time in vivo dosimetric verification method for high-dose rate intracavitary brachytherapy of nasopharyngeal carcinoma". United States. doi:10.1118/1.4758067.
@article{osti_22099079,
title = {A real-time in vivo dosimetric verification method for high-dose rate intracavitary brachytherapy of nasopharyngeal carcinoma},
author = {Qi Zhenyu and Deng Xiaowu and Cao Xinping and Huang Shaomin and Lerch, Michael and Rosenfeld, Anatoly and State Key Laboratory of Oncology in South China, Sun Yat-sen University Cancer Center, Guangzhou 510060 and Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW 2522},
abstractNote = {Purpose: A real-time in vivo dosimetric verification method using metal-oxide-semiconductor field effect transistor (MOSFET) dosimeters has been developed for patient dosimetry in high-dose rate (HDR) intracavitary brachytherapy of nasopharyngeal carcinoma (NPC). Methods: The necessary calibration and correction factors for MOSFET measurements in {sup 192}Iridium source were determined in a water phantom. With the detector placed inside a custom-made nasopharyngeal applicator, the actual dose delivered to the tumor was measured in vivo and compared to the calculated values using a commercial brachytherapy planning system. Results: Five MOSFETs were independently calibrated with the HDR source, yielding calibration factors of 0.48 {+-} 0.007 cGy/mV. The maximum sensitivity variation was no more than 7% in the clinically relevant distance range of 1-5 cm from the source. A total of 70 in vivo measurements in 11 NPC patients demonstrated good agreement with the treatment planning. The mean differences between the planned and the actually delivered dose within a single treatment fraction were -0.1%{+-} 3.8% and -0.1%{+-} 3.7%, respectively, for right and left side assessments. The maximum dose deviation was less than 8.5%. Conclusions: In vivo measurement using the real-time MOSFET dosimetry system is possible to evaluate the actual dose to the tumor received by the patient during a treatment fraction and thus can offer another line of security to detect and prevent large errors.},
doi = {10.1118/1.4758067},
journal = {Medical Physics},
issn = {0094-2405},
number = 11,
volume = 39,
place = {United States},
year = {2012},
month = {11}
}