Characterization of a water-equivalent fiber-optic coupled dosimeter for use in diagnostic radiology

This work reports on the characterization of a new fiber-optic coupled (FOC) dosimeter for use in the diagnostic radiology energy range. The FOC dosimeter was constructed by coupling a small cylindrical plastic scintillator, 500 microm in diameter and 2 mm in length, to a 2 m long optical fiber, whi...

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Bibliographic Details
Published inMedical physics (Lancaster) Vol. 36; no. 5; p. 1711
Main Authors Hyer, Daniel E, Fisher, Ryan F, Hintenlang, David E
Format Journal Article
LanguageEnglish
Published United States 01.05.2009
Subjects
Computer-Aided Design
Equipment Design
Equipment Failure Analysis
Fiber Optic Technology - instrumentation
Radiation Dosage
Radiology - instrumentation
Radiometry - instrumentation
Reproducibility of Results
Sensitivity and Specificity
Water - chemistry
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Summary:This work reports on the characterization of a new fiber-optic coupled (FOC) dosimeter for use in the diagnostic radiology energy range. The FOC dosimeter was constructed by coupling a small cylindrical plastic scintillator, 500 microm in diameter and 2 mm in length, to a 2 m long optical fiber, which acts as a light guide to transmit scintillation photons from the sensitive element to a photo-multiplier tube (PMT). A serial port interface on the PMT permits real-time monitoring of light output from the dosimeter via a custom computer program. The FOC dosimeter offered excellent sensitivity and reproducibility, allowing doses as low as 0.16 mGy to be measured with a coefficient of variation of only 3.64%. Dose linearity was also excellent with a correlation coefficient of 1.000 over exposures ranging from 0.16 to 57.29 mGy. The FOC dosimeter exhibited little angular dependence from axial irradiation, varying by less than 5% over an entire revolution. A positive energy dependence was observed and measurements performed within a scatter medium yielded a 10% variation in sensitivity as beam quality changed due to hardening and scatter across a 16 cm depth range. The current dosimetry system features an array of five PMTs to allow multiple FOC dosimeters to be monitored simultaneously. Overall, the system allows for rapid and accurate dose measurements relevant to a range of diagnostic imaging applications.
ISSN:0094-2405
DOI:10.1118/1.3116362