The influence of scout scanning parameters on image quality and radiation dose of chest CT: a phantom study
10.3760/cma.j.issn.0254-5098.2021.03.011
- VernacularTitle:定位像扫描参数对胸部CT影像质量和辐射剂量影响的模体研究
- Author:
Dandan LIU
;
Ying CUI
;
Bo ZHAO
;
Yongxian ZHANG
;
Yantao NIU
- From:
Chinese Journal of Radiological Medicine and Protection
2021;41(3):217-221
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To explore the effects of scout scanning parameters (projection angle and tube potential) on image quality and radiation dose in chest CT and to provide guidance for the selection of scanning parameters in clinical practice.Methods:Different parameter combinations were selected to acquire the scout view of the anthropomorphic adult chest phantom. Fifteen scout views were obtained under parameter combinations of the projection angle (0/90/180 degrees), tube potential (70/80/100/120/140 kV) and tube current (25 mA). And then, chest spiral scans were performed according to the scout views. The other parameters were Assist kV, smart mA (maximum range), 80 mm detector width, 0.992∶1 pitch, 0.5 s rotation time, 330 mm scanning length, 5 mm thickness, NI (noise index) 10. The radiation dose modulation index (ASiR-V) was 30%, and the iterative level was 50%. Volume CT dose index (CTDI vol) and tube current at 4 body levels (pulmonary apex, trachea bifurcation, mammary level and diaphragmatic dome) were recorded. The thermoluminescent dosimeters (TLDs) were used to measure the organ dose of the breast glandular. Regions of interest (ROIs)were selected at the trachea bifurcation and diaphragmatic dome to calculate the contrast noise ratio (CNR). Results:The tube potential of the spiral scanning was automatically selected as 80 kV when the projection angle was 0 degree. The changing of the tube potential for the scout had little influence on the tube current at the four body levels, and the variation range was 0-2% (5/230). The tube potential in the spiral scanning was automatically selected as 100 kV when the projection angles were 90 and 180 degrees. The changing of the tube potential for the scout had a great influence on the tube current at the slice of trachea bifurcation and the variation range was from 14%(29/210)to 44%(93/210). According to the angle projection, there were statistical differences in CTDI vol( P< 0.017), organ dose of the breast glandular, and CNR at the slices of trachea bifurcation and at diaphragmatic dome ( F=13.027, 24.727, 10.630, P< 0.05). According to the tube potential in the scout scanning, there were no significant differences in CTDI vol, organ dose of the breast glandular and CNR at both levels ( P> 0.05). Conclusions:In chest CT, the influence of the projection angle in scout scanning on the image quality and radiation dose was more significant than that of the tube potential.
