Objective:To investigate the relationship between tube voltage kV value for head and neck CT angiography and body weight.Methods:A total of 120 patients with suspected vascular disease of the head and neck who underwent CT angiography of the head and neck in Beihai People's Hospital from January 2020 to May 2022 were included in this study. Patients were divided into three groups according to different tube voltages: group A (tube voltage 120 kV, n = 45), group B (tube voltage 100 kV, n = 45) and group C (tube voltage 80 kV, n = 30). Patients in group A were divided into group A1 (< 70 kg, n = 15), group A2 (70-85 kg, n = 15) and group A3 (> 85 kg, n = 15) according to different body weights. Patients in group B were divided into group B1 (< 70 kg, n = 15), group B2 (70-85 kg, n = 15) and group B3 (> 85 kg, n = 15) according to different body weights. Patients in group C were divided into group C1 (< 70 kg, n = 15) and group C2 (70-85 kg, n = 15) according to different body weights. Group C3 was not used. The contrast medium used was Loversol. The CT value, image noise, signal-to-noise ratio, contrast to noise ratio, and effective radiation dose of arterial vessels in each group were measured. The images were subjectively evaluated by two physicians who had senior professional titles using a 5-point rating scale. Results:Subjective score of image quality was all ≥ 3 grade in each group. There was no significant difference in image quality rating between groups A1 and A2 and groups B1, B2, and C1. There was a remarkable difference in image quality rating between groups A3, B3, and C2 and the other groups. There was a significant difference in the CT value of blood vessels at four different levels between groups A1, B1 and C1 ( F = 76.82, 64.62, 98.79, 71.85, all P < 0.001). There was a significant difference in CT value of blood vessels at four different levels between groups A2, B2 and C2 ( F = 159.82, 112.33, 108.22, 135.18, all P < 0.001). There was a significant difference in CT value of blood vessels at four different levels between groups A3 and B3 ( t = 4.40, 4.27, 3.91, 3.59, all P < 0.05). In groups B3 and C2, the image noise was remarkably increased, signal to noise ratio and contrast to noise ratio were remarkably decreased compared with those in the other groups. The effective radiation dose of arterial vessels in group B1 was 47% lower than that in group A1 and the effective radiation dose of arterial vessels in group C1 was 73% lower than that in group A1 ( F = 116.18, P < 0.001). The effective radiation dose of arterial vessels in group B2 was 49% lower than that in group A2, and the effective radiation dose of arterial vessels in group C2 was 66% lower than that in group A2 ( H = 35.40, P < 0.001). The effective radiation dose in group B3 was 35% lower than that in group A3 ( t = 3.59, P < 0.05). Conclusion:In CT angiography of the head and neck, the selection of tube voltage kV value is related to body weight. Tube voltage 80 kV is suitable for patients with a body weight < 70 kg, tube voltage 100 kV for patients with a body weight of 70-85 kg, and tube voltage 120 kV for patients with a body weight > 85 kg. These tube voltages can decrease effective radiation dose and ensure image quality, meeting the requirement for clinical diagnosis.

Objective To explore the application value of multidetector computed tomography(MDCT),computed tomography cholangiography(CTC)and computed tomography angiography(CTA)reconstruction technology in the diagnosis and classification and the evaluation of the efficacy of biliary drainage in advanced hilar cholangiocarcinoma(HCCA).Methods A total of 44 patients of inoperable advanced HCCA were collected.Conventional CT plain scan and enhanced multi-phase scan were performed before treat-ment.Minimum intensity projection(MinIP)combined with curve planar reformation(CPR)was used to perform CTC.CTA of the portal vein,hepatic artery and hepatic vein were performed by maximum intensity projection(MIP),volume rendering(VR)or CPR,respectively.CT was reexamined after biliary drainage treatment.The study included the comparison between reconstruction technology of CTC and CTA and conventional CT scanning technology,CTC in the classification and diagnosis of HCCA,CTA in the evaluation of vascular invasion,and the evaluation of the effect of jaundice drainage by biliary imaging before and after biliary drain-age treatment.Results All HCCA cases obtained clear location diagnosis,including 39 cases of Bismuth-Corlette type Ⅳ and 5 cases of type Ⅲ.There were 40 cases of hepatic vascular involvement,including 15 cases of bilateral portal vein invasion by tumor,12 cases of portal vein constriction,8 cases of portal vein tumor thrombosis,4 cases of bilateral hepatic arteries involvement,and 1 case of hepatic vein involvement.CTC and CTA could better display a full view of the bile duct and blood vessel than conventional CT scanning ima-ges,and provided more accurate analysis of tumor classification and degree of vascular invasion.Before treatment,CT showed severe dila-tion of bile duct in 21 cases and moderate dilation in 20 cases,severe dilation of the intrahepatic bile duct in the left lobe but mild dilation of the intrahepatic bile duct in the right lobe in 3 cases.After drainage treatment,the contraction rate of intrahepatic bile duct dilation was＜25％in 4 cases,25％to 49％in 13 cases,50％to 74％in 18 cases,and ≥75％in 9 cases.The bile duct contraction rate was positively correlated with the decrease in total bilirubin(TBIL).Conclusion MDCT,CTC and CT A reconstruction technology can well complete the diagnosis of advanced HCCA,Bismuth-Corlette typing,and vascular evaluation.Observing the contraction rate of the intrahepatic bile duct after biliary drainage treatment can evaluate the efficacy of jaundice drainage.