Imaging Technology
A study on radiation dose and image quality of chest spectral imaging and conventional CT in anthropomorphic phantom
Xu Qiuzhen, Shao Hailei, Lyu Yan, Guo Wenwen
Published 2017-12-25
Cite as Chin J Radiol Med Prot, 2017,37(12): 957-961. DOI: 10.3760/cma.j.issn.0254-5098.2017.12.015
Abstract
ObjectiveTo obtain the parameters of optimal spectral scanning mode in chest spectral CT imaging, radiation doses, image quality, CNR and subjective scores are compared in spectral and conventional scan modes with anthropomorphic chest phantom.
MethodsAn anthropomorphic chest phantom underwent both conventional scan and spectral scan using three different protocols: GSI assist mode (protocol A); GSI mode with mean tube current (protocol B); GSI mode with maximum tube current(protocol C). All above scans were performed with the noise index (NI) as 9 and 11 respectively. The radiation dose was recorded, and the SD values of adipose tissue and muscle tissue of 5 different sections were measured in regions of interest (ROIs) to evaluate the image quality. All scans were subjectively scored in 5 score system by two senior radiologists on lung markings and branches with the lung window technique.
ResultsThe effective dose (E)values of conventional CT scan and protocols A, B and C were 8.0, 8.5, 6.2, 10.4 and 5.3, 5.1, 4.3, 6.2 mSv. When NI=9, the difference of SD values had statistically significance between conventional scan and protocols A, C (F=4.496, P<0.05). When NI=11, there was statistically significant difference of SD value between conventional scan and protocols A, B, C (F=8.425, P<0.05). In conventional chest scan, the difference of SD values was statistically significant between NI=9 and 11 (t=-2.570, P<0.05), while other protocols had no statistically significant difference(P>0.05). The difference of CNR and subjective score had no statistically significance in either the same NI different scanning modes or the same scanning mode with different NIs.
ConclusionsAppropriate spectral scanning mode had no significant difference with conventional CT scanning in radiation dose, yet higher image quality can be obtained. Furthermore, appropriate NI can reduce the radiation dose obviously while the similar image quality was achieved. Considering the two factors, GSI assist mode can achieve balance between radiation dose and image quality.
Key words:
Anthropomorphic chest phantom; Spectral CT; Conventional CT; Image quality; Radiation dose
Contributor Information
Xu Qiuzhen
Department of Radiology, Southeast University Medical College, Affiliated Zhongda Hospital of Southeast University, Nanjing 210009, China
Shao Hailei
Lyu Yan
Guo Wenwen
