Congress:
EuroSafe Imaging 2020
Keywords:
Performed at one institution, Case-control study, Retrospective, Kv imaging, Artifacts, Radiation safety, Comparative studies, CT, Paediatric, CNS
Authors:
S. Ariyoshi, M. Okada , K. Takegami, S. Kudomi, K. Ito
DOI:
10.26044/esi2020/ESI-06847
Description of activity and work performed
Study population
This retrospective study included 9 patients under the age of 10 who underwent head CT localizer with and without tin filtration. The CT scans performed with SOMATOM Drive (Siemens Healthcare, Germany) with Tin-filter and SOMATOM Force (Siemens Healthcare, Germany) without Tin-filter. Automatic exposure control was used for all scans.
The radiation exposure was assessed as volumetric CT dose index(CTDIvol) and dose-length product (DLP) provided by these scanners.
Image quality analysis
Two radiology technologists categorized the image quality (IQ) using a 3-grade scale (0:Unsuitable for scouting, 1:Fair, 2:Good). Representative images of score 1 and 2 are shown in Fig.1 and FIg.2.
Region of interest was placed in head localizer as large as possible and mean attenuation, image noise (standard deviation: SD), signal to noise ratio (SNR) and contrast to noise ratio (CNR) were calculated and as a reference, surrounding air was also measured.
Results
Among these 9 patients, none of the patients were re-scanned because of poor image quality of survey images. The CTDIvol of survey images was significantly lower in the Tin-filter group (0.01 mGy) than the non-Tin-filter group (0.08 mGy) (p<0.0001). The mean attenuation of air and skull were, -51.5 HU(SD; 3.57) and 19.6HU(SD; 5.45) in the Tin-filter group and -51.31 HU(SD; 1.62) and 17.6HU(SD; 4.68) in the non-Tin-filter group, respectively. Large SD led to significantly lower SNR and CNR in the Tin-filter group than the non-Tin-filter group (p<0.01) respectively. However, there was no significant difference in IQ between the two groups (ICC=0.83, 0.93, respectively).