Abdominal CT during pregnancy: a phantom study on the effect of patient centring on conceptus radiation dose and image quality

• Published in: European radiology Vol. 25; no. 4; pp. 911 - 921
• Main Authors: Solomou, G., Papadakis, A. E., Damilakis, J.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.04.2015; Springer Nature B.V
• Subjects: Abdomen; Anthropomorphism; Contrast Media; Diagnostic Radiology; Female; Health physics; Humans; Imaging; Internal Medicine; Interventional Radiology; Medicine; Medicine & Public Health; Neuroradiology; Patients; Phantoms, Imaging; Physics; Pregnancy; Radiation; Radiation Dosage; Radiography, Abdominal; Radiology; Signal to noise ratio; Tomography; Tomography, X-Ray Computed - methods; Ultrasound; Crete; Germany; Image quality; Vertical miscentring; Horizontal miscentring; Automatic exposure control; Conceptus radiation dose
• ISSN: 0938-7994; 1432-1084
• DOI: 10.1007/s00330-014-3505-2

Objectives To investigate the effect of patient centring on conceptus radiation dose and image quality in abdominal CT during pregnancy. Material and methods Three anthropomorphic phantoms that represent a pregnant woman at the three trimesters of gestation were subjected to a routine abdominal CT. Examinations were performed with fixed mAs (mAs f ) and with the automatic exposure control system (AEC) activated. The percent reduction between mAs f and modulated mAs (mAs mod ) was calculated. Conceptus dose (D c ) was measured using thermoluminencent dosimeters. To study the effect of misplacement of pregnant women on D c , each phantom was positioned at various locations relative to gantry isocentre. Image quality was evaluated on the basis of image noise, signal-to-noise ratio, and contrast-to-noise ratio. Results The maximum reduction between mAs f and mAs mod was 59.8 %, while the corresponding D C reduction was 59.3 %. D C was found to decrease by up to 25 % and 7.9 % for phantom locations below and above the isocentre, respectively. Image quality deteriorated when AEC was activated, and it was progressively improved from lower to higher than the isocentre locations. Conclusion Centring errors do not result in an increase in D c . To maintain image quality, accurate centring is required. Key Points • AEC activation reduces conceptus radiation dose at all gestational stages. • Patients should be accurately aligned at the gantry isocenter. • Patient centring deserves increased attention in clinical practice. • Pregnant patient centring errors do not considerably affect conceptus dose.