Increased Computed Tomography Dose Due to Miscentering With Use of Automated Tube Voltage Selection: Phantom and Patient Study

• Published in: Current problems in diagnostic radiology 2016-07, Vol.45 (4), p.265-270
• Main Authors: Filev, Peter D., MD, Mittal, Pardeep K., MD, Tang, Xiangyang, PhD, Duong, Phuong-Anh, MD, Wang, Xiaojing, MPH, Small, William C., MD, PhD, Applegate, Kimberly, MD, Moreno, Courtney C., MD
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Child; Child, Preschool; Female; Humans; Image Processing, Computer-Assisted - methods; Infant; Internal Medicine; Male; Medical Errors - statistics & numerical data; Middle Aged; Phantoms, Imaging; Radiation Dosage; Radiology; Retrospective Studies; Software; Tomography, X-Ray Computed - instrumentation; Tomography, X-Ray Computed - methods; Young Adult
• ISSN: 0363-0188; 1535-6302
• DOI: 10.1067/j.cpradiol.2015.11.003

The purpose of the article is to determine if miscentering affected dose with use of automated tube voltage selection software. An anthropomorphic phantom was imaged at different table heights (centered in the computed tomography [CT] gantry, and −6, −3, +3, and +5.7 cm relative to the centered position). Topogram magnification, tube voltage selection, and dose were assessed. Effect of table height on dose also was assessed retrospectively in human subjects ( n = 50). When the CT table was positioned closer to the x-ray source, subjects appeared up to 33% magnified in topogram images. When subjects appeared magnified in topogram images, automated software selected higher tube potentials and tube currents that were based on the magnified size of the subject rather than the subject׳s true size. Table height strongly correlated with CT dose index ( r = 0.98, P < 0.05) and dose length product ( r = 0.98, P < 0.05) in the phantom study. Transverse dimension in the topogram highly correlated with dose in human subjects ( r = 0.75-0.87, P