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

Journal Article


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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 192Iridium 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 cGymV. 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.

Publication Date


  • 2012

Citation


  • Qi, Z., Deng, X., Cao, X., Huang, S., Lerch, M. & Rozenfeld, A. (2012). A real-time in vivo dosimetric verification method for high-dose rate intracavitary brachytherapy of nasopharyngeal carcinoma. Medical Physics, 39 (11), 6757-6763.

Scopus Eid


  • 2-s2.0-84868543505

Ro Full-text Url


  • http://ro.uow.edu.au/cgi/viewcontent.cgi?article=1017&context=eispapers

Ro Metadata Url


  • http://ro.uow.edu.au/eispapers/15

Number Of Pages


  • 6

Start Page


  • 6757

End Page


  • 6763

Volume


  • 39

Issue


  • 11

Place Of Publication


  • http://dx.doi.org.ezproxy.uow.edu.au/10.1118/1.4758067

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 192Iridium 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 cGymV. 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.

Publication Date


  • 2012

Citation


  • Qi, Z., Deng, X., Cao, X., Huang, S., Lerch, M. & Rozenfeld, A. (2012). A real-time in vivo dosimetric verification method for high-dose rate intracavitary brachytherapy of nasopharyngeal carcinoma. Medical Physics, 39 (11), 6757-6763.

Scopus Eid


  • 2-s2.0-84868543505

Ro Full-text Url


  • http://ro.uow.edu.au/cgi/viewcontent.cgi?article=1017&context=eispapers

Ro Metadata Url


  • http://ro.uow.edu.au/eispapers/15

Number Of Pages


  • 6

Start Page


  • 6757

End Page


  • 6763

Volume


  • 39

Issue


  • 11

Place Of Publication


  • http://dx.doi.org.ezproxy.uow.edu.au/10.1118/1.4758067