Performance of a near-real-time KBr:Eu dosimetry system under computed tomography x-rays

• Published in: Radiation measurements 2010-03, Vol.45 (3), p.663-667
• Main Authors: Klein, David, Peakheart, David W., McKeever, Stephen W.S.
• Format: Article
• Language: English
• Subjects: Earth sciences; Earth, ocean, space; Exact sciences and technology; Geochronology; Isotope geochemistry. Geochronology; OSL dosimetry; Real-time dosimetry; Remote dosimetry
• ISSN: 1350-4487; 1879-0925
• DOI: 10.1016/j.radmeas.2009.11.043

The dynamic radiation fields used in Computed Tomography (CT) scans are difficult to characterize quickly using dosimetry techniques that utilize large-volume detectors (e.g. ionization chambers) or passive detectors (e.g., thermoluminescent dosimeters). In this study we demonstrate the feasibility of using the optically stimulated luminescence (OSL) of KBr:Eu for quantitative CT dose measurements. The particular OSL method used is capable of acquiring full OSL signals at a rate of 10 Hz, which allows for near-real-time active dosimetry. The portable reader system connects to the KBr:Eu dosimeter via a fiber-optic cable, through which both stimulation light and OSL propagate. The small volume (∼2 mm 3) of the KBr:Eu dosimeter also allows the system to resolve detailed structures in complex radiation fields. Testing of the KBr:Eu dosimetry system under axial and helical CT scanning showed that the fast data acquisition and small dosimeter volume allowed for high-resolution dose profiling using a cylindrical CT body phantom. The dose response of the dosimetry system compared favorably to exposure results reported by a standard 100 mm pencil ionization chamber. A dependence of the OSL output from the KBr:Eu crystal on x-ray energy was also observed. These and similar observations are discussed in detail.