ABSTRACT
Objective:To understand the current situation of CT radiation dose in children all over our country, and to explore the diagnostic reference level (DRL) of CT in children.Methods:The radiation dose reports of pediatric CT examination were collected end to November 30, 2021 and divided into five age groups: 0-1 month,>1 month-4 years,>4-10 years,>10-14 years and >14-18 years. There were 9 scanning item such as head, nasal sinus, temporal bone, neck, chest, abdomen, head enhanced CT, chest enhanced CT and abdomen enhanced CT. In each item, volume CT dose index (CTDI vol) and dose length product (DLP) were selected as radiation dose parameters, the 75% percentile were selected for DRL. The DRL results of head, chest and abdomen were compared with the DRL published by Chinese Society of Radiology and European Commission. Results:From March 2019 to November 2021, a total of 33 hospitals in 23 provinces were collected, including 20 children′s specialized hospitals, 11 women′s and children′s hospitals and 2 general hospitals, including 19 135 children′s CT scans. The DRL of 45 subgroups according to 5 age groups and 9 scanning items were obtained. The DRL results showed that the CTDI vol in five age groups was 26.9-42.8 mGy, and the DLP was 347-694 mGy·cm for head; 3.5-8.0 mGy, 54-293 mGy·cm for chest; and 6.3-13.2 mGy, 155-564 mGy·cm for abdomen. The DRL of the age group >4-10 years group in this investigation was agreed to the DRL of Chinese Society of Radiology. Compared with the European guidelines, there was little difference in the radiation dose of head scan, while the radiation dose of chest and abdomen in the young age group increased significantly. Conclusion:This survey reveals the radiation dose level distribution of children CT in our country. The radiation dose level of some items was inconsistent with the DRL of relevant international organizations. So our own DRL is needed to be set up according to the actual clinical reality of our country as a guideline.
ABSTRACT
Objective:To demonstrate whether image quality and measurement accuracy of vessel wall thickening could be improved using a deep learning image reconstruction (DLIR) algorithm in children with Takayasu arteritis.Methods:From September 2019 to April 2020, 32 patients with Takayasu arteritis underwent low-dose contrast-enhanced CT with 100 kVp in Beijing Children′s Hospital were enrolled retrospectively. The raw data were reconstructed at 0.625 mm slice thickness using the filtered back projection (FBP), 50% adaptive statistical iterative reconstruction-V (ASIR-V) at 50% (50%ASIR-V), ASIR-V at 100% (100%ASIR-V) and DLIR. Subjective evaluation including the image quality of vessel wall identification, overall image noise and diagnostic confidence were evaluated using a 5 points scales by 2 observers. Objective evaluation including the thickness and standard deviation of vessel wall were measured, then the coefficient of variation (CV) was calculated. The CT value and noise of aorta were measured to calculate the contrast to noise ratio (CNR) of image. Friedman test was used to compare the differences of subjective scores among the four groups, and the analysis of variance of random blocks was used to compare the differences of objective measurement indices.Results:In terms of subjective score results, there was no significant difference between 100%ASIR-V and DLIR of overall image noise ( P>0.05), and the image scores of the two groups were higher than those of FBP and 50%ASIR-V (all P<0.05). The vessel wall identification and diagnostic confidence of DLIR were higher than those of other images (all P<0.05). The objective measurement results showed that the standard deviation and CV of vessel wall thickness in DLIR were significantly lower than those in other images (all P<0.05). There was no significant difference in vascular noise, muscle noise and CNR between 100%ASIR-V and DLIR (all P>0.05), which were lower than those in FBP and 50%ASIR-V (all P<0.05). Compared with 50%ASIR-V, the CV of DLIR was reduced by 22.9%, and the CNR was increased by 46.8%. Conclusion:DLIR can improve the overall image quality of CECT in children with Takayasu arteritis and the measurement accuracy of vascular wall, making it possible to further reduce the radiation dose.
ABSTRACT
Objective To explore the value of snapshot freeze (SSF) technique in coronary CTA (CCTA) in pediatric patients with high heart rates. Methods Totally 50 children whose heart rate were ≥ 75 times per minute were selected and underwent CCTA. The raw data were reconstructed into 4 groups. The best phase in group A was manually selected without SSF technique, in group B was manually selected with SSF, in group C was automatically selected (Smart Phase) without SSF, while in group D was automatically selected with SSF. The image quality scores and diagnostic rates of coronary artery were compared among 4 groups. Results Totally 675 branches were assessed in 50 patients. There was no significant difference of left circumflex artery (LCX) image quality scores nor diagnostic rates among 4 groups (both P>0.05). There were significant differences of right coronary artery (RCA), left anterior descending (LAD), total coronary artery scores and diagnostic rates (all P<0.05). Significant differences of RCA and coronary artery scores were found (both P<0.01), while no significant difference of LAD scores was detected (P=0.08) between group A and B. There were significant differences of LAD and coronary artery diagnostic rates (both P<0.01), while no significant difference of RCA diagnostic rates was found (P=0.08) between group A and B. Significant differences of RCA, LAD and coronary artery scores and diagnostic rates were observed between group C and D (all P<0.05). Conclusion SSF technique can improve image quality of CCTA in children with high heart rate.
ABSTRACT
Objective To assess the feasibility of low concentration contrast medium (270 mgI/ml) and low radiation dose (100 kV) for enhanced CT scanning in infants and young children abdominal CT examination.Methods Ninety children with abdomen tumors or abdominal injuries who underwent contrast-enhanced CT examination were selected.The patients were divided into 3 groups (each n＝ 30):Group A with tube voltage of 120 kV for non-contrast enhanced and parenchymal phase scanning and iodixanol contrast-medium (320 mgI/ml);group B with tube voltage of 100 kV for non-contrast enhanced and parenchyrnal phase scanning and iodixanol contrast-medium (270 mgI/rnl);group C with tube voltage of 100 kV for non-contrast enhanced and parenchymal phase scanning and iodixanol contrast-medium (270 mgI/ml).The 4-point scale was used to evaluate the quality of parenchymal phase imaging.The standard difference (SD) of CT value in subcutaneous fat,SNR and CNR of liver parenchyma,splenic parenchyma,renal cortical,renal vein,and abdominal aorta were measured at parenchymal phase,and CT dose index of volume (CTDI,ol),dose length product (DLP) and effective dose (ED) were recorded.The data were statistically analyzed among 3 groups.Results There was no significant difference of SNR,CNR nor objective scores of liver parenchyma,splenic parenchyma,renal cortical,renal vein and abdominal aorta among 3 groups (all P＞0.05).The differences of CTDIvol,DLP and ED among 3 groups were statistically significant (all P＜0.01).The CTDIvol had no statistical difference between group B and group C (P ＝ 0.001,0.002),DLP (P ＝ 0.013,0.004) and ED (P ＝ 0.03,＜0.001) of group A had statistical difference with those of group B and C.Conclusion CNR of the abdominal image can be guaranteed using low concentration contrast medium (270 mgI/ml) combined with 100 kV tube voltage for CT scanning of infants and young children,therefore satisfying clinical diagnostic requirements.
ABSTRACT
Objective To evaluate the feasibility of model-based iterative reconstruction (MBIR) in low-dose chest CT (80 kV) examination in children.Methods Forty-four children who had post-operation scoliosis and received low dose chest CT scans were included.The fix tube voltage was 80 kV,fix current was 50 mA.Images were reconstructed with MBIR (observation group).The pre-operation scan were used 120 kV and 50 mA for acquisition,and images were reconstructed with filtered back-projection (FBP) mehed (control group).The subjective quality of the images was independently evaluated by two radiologists.Objective noises in the muscle and lung field were measured,the SNR,CNR were calculated,and the CTDIvol was record.Results The subjective noise score in the observation group was significantly higher than that in the control group (P＜0.05).Objective noise reduced about 40.36％,SNR increased 72.37％,CNR increased 78.69％,CTDIvol decreased by 66.52％,all of which had statistical difference between both groups (all P＜0.001).Conclusion Low-dose chest CT (80 kV) examination in children can meet the requirements of diagnosis for children.