The in vivo relationship between cross-sectional area and CT dose index in abdominal multidetector CT with automatic exposure control.

Journal article

The relationship between patient cross-sectional area and both volume CT dose index (CTDI) and dose length product was explored for abdominal CT in vivo, using a 16 multidetector row CT (MDCT) scanner with automatic exposure control. During a year-long retrospective survey of patients with MDCT for symptoms of abdominal sepsis, cross-sectional areas were estimated using customised ellipses at the level of the middle of vertebra L3. The relationship between cross-sectional area and the exposure parameters was explored. Scans were performed using a LightSpeed 16 (GE Healthcare Medical Systems, Milwaukee, WI) operated with tube current modulation. From a survey of 94 patients it was found that the CTDI increased with the increase in patient cross-sectional area. The relationship was logarithmic rather than linear, with a least-squares fit to the data (R(2) = 0.80). For abdominal CT the cross-sectional area gave a measure of patient size based on the region of the body to be exposed. Exposure parameters increased with increasing cross-sectional area and the greater radiation exposure of larger patients was partly a consequence of their size. Given increasing obesity levels we believe that cross-sectional area and scan length should be added to future dose surveys, allowing patient size to be considered as a factor of relevance when examining population doses.

Authors: Meeson, S; Alvey, C; Golding, S

• Publication status: Published
• Journal: Journal of radiological protection : official journal of the Society for Radiological Protection
• Volume: 30
• Issue: 2
• Pages: 139-147
• Publication date: 2010-06-01
• DOI: 10.1088/0952-4746/30/2/003
• EISSN: 1361-6498
• ISSN: 0952-4746
• Language: English
• Keywords: Radiography, Abdominal; Abdomen; Middle Aged; Radiation Dosage; Organ Size; Great Britain; Body Size; Tomography, X-Ray Computed; Humans; Male; Risk Assessment; Body Burden; Female; Statistics as Topic