Radiation dose control for CT urography based on different body mass index
10.3760/cma.j.issn.0254-5098.2020.01.012
- VernacularTitle: 基于不同体质量指数CT尿路成像辐射剂量控制
- Author:
Haijing QIU
1
;
Yong CHEN
2
;
Tao REN
3
;
Yujia GAO
3
;
Wenjie SUN
3
;
Zhiling GAO
4
Author Information
1. Clinical Medical College of Ningxia Medical University, Yinchuan 750004, China(Qiu Haijing is working in the department of radiology, the Second Affiliate Hospital of Xi′an Medical College, Xi′an 710038, China)
2. Department of Radiology and Intervention, The General Hospital of Ningxia Medical University, Yinchuan 750004, China
3. Clinical Medical College of Ningxia Medical University, Yinchuan 750004, China
4. Department of Radiology, The General Hospital of Ningxia Medical University, Yinchuan 750004, China
- Publication Type:Journal Article
- Keywords:
Body mass index;
CT urography;
Low-dose scan;
Urinary system disease
- From:
Chinese Journal of Radiological Medicine and Protection
2020;40(1):64-70
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To explore the optimization of CT urography imaging parameters and the control measures of radiation dose to patients with different body mass index.
Methods:A total of 133 patients who were required to undergo CT urography were prospectively selected in terms of three different types of CT urography scan; firstly, conventional parameter scan (120 kV, CARE Dose4D); secondly, low kV scan (BMI ≤ 22.9∶80 kV, 22.9 < BMI < 30∶100 kV, BMI ≥ 30∶120 kV, CARE Dose4D) and thirdly, low mAs scan (120 kV, 40% reduction in mAs on CARE Dose4D). Noise, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of all images were measured as objective evaluation indicators of image quality. The subjective evaluation of the images was performed by two radiologists who had been working for more than five years using a double-blind method and a 5-score system evaluation. The effective dose values (CTDIvol, DLP, E) in each group were measured.
Results:Patients′ effective dose was decreased by 77.7% in 80 kV group and 38.3% in 100 kV group, with a statistical difference between the two groups (Z=-3.330, -5.559, P<0.05). There was a statistically significant difference in renal cortex noise, SNR, CNR and ureteral noise between the 80 kV scan and the routine scan (Z=-3.705-2.392, P<0.05), but no significant difference in ureteral SNR, CNR and renal pelvis noise, SNR, CNR (P>0.05). There was a statistically significant difference in renal cortex noise and SNR between the 100 kV scan group and the routine scan group (Z=-5.096, -3.566, P<0.05), but no statistical difference in renal cortex CNR, renal pelvis and ureteral noise, SNR, CNR(Z=-5.086, -5.912, -2.842, P>0.05). The effective dose from low mAs scan in the three types of patients was decreased by 38.3%, 32.0%, and 34.7%, respectively, with a statistical difference between them (P <0.05). There was no significant difference in noise, SNR, and CNR between renal cortex, renal pelvis and ureter (P>0.05) besides ureteral CNR in the 22.9 < BMI < 30 group (Z=-2.587, P<0.05). The subjective evaluation scores of all images were greater than 3 points.
Conclusions:In this study, the scan method for low kV and low mAs used for patients with different body mass index can effectively reduce the radiation dose to patients and meet the requirements of clinical diagnosis.
