Prog Med Phys.  2016 Dec;27(4):213-219. 10.14316/pmp.2016.27.4.213.

Feasibility Study of Source Position Verification in HDR Brachytherapy Using Scintillating Fiber

• Moon SY
• Jeong E
• Lim YK
• Chung WK
• Huh HD
• Kim DW
• Yoon M

• KMID: 2376554
• DOI: http://doi.org/10.14316/pmp.2016.27.4.213

Abstract

The position verification of the radiation source utilized in brachytherapy forms a critical factor in determining the therapeutic efficiency. Currently, films are used to verify the source position; however, this method is encumbered by the lengthy time interval required from film scanning to analysis, which makes real-time position verification difficult. In general, the source position accuracy is usually tested in a monthly quality assurance check. In this context, this study investigates the feasibility of the real-time position verification of the radiation source in high dose rate (HDR) brachytherapy with the use of scintillating fibers. To this end, we construct a system consisting of scintillating fibers and a silicon photomultiplier (SiPM), optimize the dosimetric software setup and radiation system characteristics to obtain maximum measurement accuracy, and determine the relative ratio of the measured signals dependent upon the position of the scintillating fiber. According to the dosimetric results based on a treatment plan, in which the dwell time is set at 30 and 60 s at two dwell positions, the number of signals is 31.5 and 83, respectively. In other words, the signal rate roughly doubles in proportion to the dwell time. The source position can also be confirmed at the same time. With further improvements in the spatial resolution and scintillating fiber array, the source position can be verified in real-time in clinical settings with the use of a scintillating fiber-based system.

Keyword

Brachytherapy; Dwell position; Scintillating fiber; SiPM

MeSH Terms

Brachytherapy*
Feasibility Studies*
Methods
Silicon
Silicon

Figure

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  Fig. 1. Components of the silicon photomultiplier (SiPM) system used in the study.

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  Fig. 2. Software for using silicon photomultiplier (SiPM) system provided by SENSL.

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  Fig. 3. Overall schematic of the system used in the study (Grey-Connection line, Dotted arrow-Input, Dark arrow-Output, Star-Source).

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  Fig. 4. Photograph of the actual setup used in the study.

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  Fig. 5. Output signal as a function of the dosage in our radiotherapy experiment.

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  Fig. 6. Output signal as a function of the dose rate in our radiotherapy experiment.

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  Fig. 7. Output signal as a function of the distance between fiber and source (Red line-Exponential fitting of the signal).

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  Fig. 8. Measured signal for different dwell times at two dwell positions.

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