title: IMPLICATIONS OF PATIENT CENTRING ON ORGAN DOSE IN COMPUTED TOMOGRAPHY.
abstract: Automatic exposure control (AEC) in computed tomography (CT) facilitates optimisation of dose absorbed by the patient. The use of AEC requires appropriate 'patient centring' within the gantry, since positioning the patient off-centre may affect both image quality and absorbed dose. The aim of this experimental study was to measure the variation in organ and abdominal surface dose during CT examinations of the head, neck/thorax and abdomen. The dose was compared at the isocenter with two off-centre positions-ventral and dorsal to the isocenter. Measurements were made with an anthropomorphic adult phantom and thermoluminescent dosemeters. Organs and surfaces for ventral regions received lesser dose (5.6-39.0 %) than the isocenter when the phantom was positioned +3 cm off-centre. Similarly, organ and surface doses for dorsal regions were reduced by 5.0-21.0 % at -5 cm off-centre. Therefore, correct vertical positioning of the patient at the gantry isocenter is important to maintain optimal imaging conditions.
authors.affiliation: Department of Radiology, Department of Medical & Health Sciences, Center for Medical Image Science and Visualisation, Linköping University, County Council of Östergötland, Linköping, Sweden bharti.kataria@liu.se.
authors.forename: Bharti
authors.initials: B
authors.lastname: Kataria
authors.affiliation: Department of Medical Physics, Department of Medical & Health Sciences, Center for Medical Image Science & Visualization, Linköping University, County Council of Östergötland, Linköping, Sweden.
authors.forename: Michael
authors.initials: M
authors.lastname: Sandborg
authors.affiliation: Department of Medical Physics, Linköping University, County Council of Östergötland, Linköping, Sweden.
authors.forename: Jonas Nilsson
authors.initials: JN
authors.lastname: Althén
mesh_terms: D006801:Humans; D056888:Patient Positioning / Q000295:instrumentation / Q000379:methods*; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D000069079:Radiation Exposure / Q000032:analysis* / Q000517:prevention & control; D011835:Radiation Protection / Q000379:methods; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D011860:Radiography, Abdominal / Q000295:instrumentation / Q000379:methods*; D011874:Radiometry / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000295:instrumentation / Q000379:methods*; D014781:Viscera / Q000528:radiation effects*