title: Characterization of a commercially-available, optically-stimulated luminescent dosimetry system for use in computed tomography.
abstract: Optically-stimulated luminescent (OSL) nanoDot dosimeters, commercially available from Landauer, Inc. (Glenwood, IL), were assessed for use in computed tomography (CT) for erasure and reusability, linearity and reproducibility of response, and angular and energy response in different scattering conditions. Following overnight exposure to fluorescent room light, the residual signal on the dosimeters was 2%. The response of the dosimeters to identical exposures was consistent, and reported doses were within 4% of each other. The dosimeters responded linearly with dose up to 1 Gy. The dosimeter response to the CT beams decreased with increased tube voltage, showing up to a -16% difference when compared to a 0.6-cm(3) NIST-traceable calibrated ionization chamber for a 135 kVp CT beam. The largest range in percent difference in dosimeter response to scatter at central and peripheral positions inside CTDI phantoms was 14% at 80 kVp CT tube voltage, when compared to the ionization chamber. The dosimeters responded uniformly to x-ray tube angle over the ranges of increments of 0° to 75° and 105° to 180° when exposed in air, and from 0° to 360° when exposed inside a CTDI phantom. While energy and scatter correction factors should be applied to dosimeter readings for the purpose of determining absolute doses, these corrections are straightforward but depend on the accuracy of the ionization chamber used for cross-calibration. The linearity and angular responses, combined with the ability to reuse the dosimeters, make this OSL system an excellent choice for clinical CT dose measurements.
authors.affiliation: Tufts Medical Center, Department of Radiology, 800 Washington St., Box 299, Boston, MA 02111, USA. LLavoie@tuftsmedicalcenter.org
authors.forename: Lindsey
authors.initials: L
authors.lastname: Lavoie
authors.forename: Monica
authors.initials: M
authors.lastname: Ghita
authors.forename: Libby
authors.initials: L
authors.lastname: Brateman
authors.forename: Manuel
authors.initials: M
authors.lastname: Arreola
mesh_terms: D002138:Calibration; D006801:Humans; D049449:Luminescence; D055096:Optical Devices; D019047:Phantoms, Imaging; D011874:Radiometry / Q000295:instrumentation / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000295:instrumentation / Q000379:methods*; D014965:X-Rays