title: Optimized control of X-ray exposure and image noise using a particular multislice CT scanner.
abstract: Patient dose reduction in computed tomography (CT) always results in a trade off between radiation exposure and image quality. There are few reports that estimate the relationship between image quality and X-ray exposure in CT examinations as one optimal index. The purpose of this study was to determine the optimal parameter settings enabling a low radiation exposure without compromising image quality using a particular 4-row multislice CT (MSCT) scanner (Aquilion VZ 4-slice CT scanner, Toshiba Medical Systems Corporation, Otawara, Tochigi, Japan). Normalized dose divided by image noise for helical pitches (nDNR: normalized dose to noise ratio) were calculated in consideration of beam collimation and tube current-time product. Optimal tube current-time product was calculated using the nDNR for the helical pitches based on user-defined standards of quality of the CT image. As a result, the nDNR proved to be well-supported to decrease the patient exposure in various exposure conditions of MSCT scans; however, the dose and image noise did not show a linear relation to the helical pitch. In conclusion, nDNR can be applied to patient dose reduction while keeping an acceptable image quality using a particular 4-row MSCT scanner.
authors.affiliation: National Cancer Center, Research Center for Cancer Prevention and Screening (3rd Term Comprehensive 10-Year Strategy for Cancer Control).
authors.forename: Shuji
authors.initials: S
authors.lastname: Yamamoto
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Koyama
authors.forename: Masahiro
authors.initials: M
authors.lastname: Suzuki
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Nagasawa
authors.forename: Ryutaro
authors.initials: R
authors.lastname: Kakinuma
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Moriyama
mesh_terms: D011829:Radiation Dosage; D014057:Tomography, X-Ray Computed / Q000295:instrumentation*