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WE‐AB‐BRB‐02: Development of a Micro‐Sized Dosimeter for Real‐Time Dose Monitoring and Small Field Dosimetry
Author(s) -
Volotskova O,
Jenkins C,
Fahimian B,
Xing L
Publication year - 2015
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.4925843
Subject(s) - dosimetry , dosimeter , detector , optics , spectrometer , ranging , dose profile , materials science , physics , imaging phantom , particle detector , photon , radiation , nuclear medicine , telecommunications , medicine , computer science
Purpose: To investigate a miniature optical dosimeter for real‐time, high‐resolution dosimetry, and explore its potential applications for in vivo measurements and small field dosimetry. Methods: A micro‐sized hemispherical (400 µm radius) scintillating detector was constructed from lanthanide activated phosphors doped with Europium (GOS:Eu) and encapsulated in a 17 gauge plastic catheter. A photon counting PMT and CCD‐chip spectrometer were used to detect signals emitted from the detector. A single band‐passing spectral approach (630nm) was implemented to discriminate the micro‐phosphor optical signal from background signals (Cerenkov radiation) in the optical fiber. To test real‐time monitoring capabilities, a 3D‐printed phantom was used to detect an 192Ir HDR brachytherapy source at locations ranging from 1 to 4 cm radially and 12 cm along the travel axis of the HDR wire. To test the application of the micro‐sized detector for small field dosimetry, the linearity of detector was characterized through irradiation of 6MV photon beam at dose‐rates ranging from 100 to 600 MU, and the effect of field size was characterized through detections of beams ranging from 30×30 to 1×1 cm2 size. Results: With a 1 second integration time for the spectrometer, the recorded measurements indicated that the micro‐sized detector allowed accurate detection of source position at distances of up to 6 cm along the axis of travel in water. EB measurements showed that the detected signal was linearly correlated with dose rate (R^2 = 0.99). The crossbeam profile was determined with a step size of ∼500 µm. Conclusion: Miniaturization of optical dosimeters is shown to be possible through the construction of lanthanide activated doped phosphors detectors. The small size of the detector makes it amenable to a variety of applications, including real‐time dose delivery verification during HDR brachytherapy and EB beam calibrations in small fields.