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Fiber Optic Dosimeters Based On Silver-Only Coated Hollow Waveguides for Radiation Therapy Dosimetry

A Darafsheh*, Washington University School of Medicine, St. Louis, MO


(Thursday, 8/2/2018) 10:00 AM - 12:00 PM

Room: Davidson Ballroom A

Purpose: In order to enhance the scintillation signal transmission while minimizing the problematic effect of ÄŒerenkov radiation contamination, we designed a fiber optic dosimeter probe using a silver-only coated hollow waveguide (HWG).

Methods: A 5-mm length piece of BCF-12 plastic scintillator with 1 mm diameter was inserted inside the bore of a silver-only HWG with 50 cm length and 1 mm inner and 1.2 mm outer diameter. A 15-m-long solid core fiber was coupled to the other end of the HWG. The HWG with scintillator inserted in its tip, embedded in solid water phantoms, was irradiated with electron and photon beams. Optical spectra of the irradiated tip were taken using a fiber spectrometer, and the signal was deconvolved with a linear fitting algorithm to measure the absorbed dose in the scintillator.

Results: The resultant decomposed spectra of the scintillator with and without ÄŒerenkov correction were in agreement with measurements performed by an electron diode and ion chamber for electron and photon beams, respectively, indicating the minimal effect of ÄŒerenkov radiation contamination. Compared with a silver/dielectric-coated HWG fiber dosimeter design, we observed ~3 times higher signal transmission in the design based on the use of silver-only HWG.

Conclusion: Using HWG minimizes the influence of ÄŒerenkov radiation contamination in fiber optic dosimetry. Compared with a silver/dielectric-coated HWG fiber dosimeter design, higher signal transmission is achieved by using a silver-only HWG. This increase in the optical throughput would specifically be more helpful for low SNR scintillation detection scenarios.


Scintillators, Optical Dosimetry


TH- External beam- photons: General (most aspects)

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