title: Comparison of three methods for determining CT dose profile: presenting the tritium method.
abstract: The purpose of the present work was to describe a method of using an imaging plate from a computed radiography system to determine the computed tomography (CT) dose profile (the tritium method) and to compare this method with point-dose measurements using a solid-state detector (CT Dose Profiler; RTI Electronics, Mölndal, Sweden) and the indirect method of comparing the air kerma-length product (P(KL)) at different beam collimations. The three methods were used to determine the full width at half maximum (FWHM) of the dose profile of a multi-slice CT at different nominal beam collimations. For all beam collimations, the obtained deviation between the tritium method and the CT Dose Profiler was smaller than 0.1 mm. The maximum relative error was 2 %. For the P(KL) method, the deviation from the CT Dose Profiler was between 0.2 and 0.4 mm, resulting in a relative error larger than 10 % for the smallest beam collimation even after normalisation to a known FWHM. In conclusion, the proposed method of using an imaging plate to determine the FWHM of the CT dose profile has a high accuracy and shows good agreement with the more advanced method of point-dose measurements using a solid-state detector.
authors.affiliation: Department of Medical Physics and Biomedical Engineering, Sahlgrenska University Hospital, Gothenburg, Sweden. jonny.hansson@vgregion.se
authors.forename: Jonny
authors.initials: J
authors.lastname: Hansson
authors.forename: Simone
authors.initials: S
authors.lastname: Eriksson
authors.forename: Anne
authors.initials: A
authors.lastname: Thilander-Klang
authors.forename: Magnus
authors.initials: M
authors.lastname: Båth
mesh_terms: D001822:Body Burden; D011829:Radiation Dosage; D011874:Radiometry / Q000295:instrumentation / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014316:Tritium / Q000528:radiation effects*; D014963:X-Ray Intensifying Screens
chemical_list: D014316:Tritium