Objective To investigate the effect of adjusting tube current time product (mAs) according to head circumference index on head CT image quality and organ-specific-dose level based on Monte Carlo analysis platform.Methods A total of 92 patients including children and adolescents with different clinical symptoms undergoing head CT scan were prospectively selected between September 2017 and June 2018 in the First Hospital of Jilin University.Without limiting the size of the head circumference,there were 22 patients were selected as conventional group by random number table,whose head circumference was 48.1-59.2 cm.Low dose group was divided into following three subgroups according to different head circumferences:A group 54.1-57.0 cm (n=22);B group 51.1-54.0 cm (n=26) and C group 48.1-51.0 cm (n=22).Tube current time product was 250 mAs for conventional group,200 mAs for A group,150 mAs for B group and 100 mAs for C group,respectively.The organ-specific-radiation doses (brain,eye lens and salivary gland) were recorded by Monte Carlo analysis platform and the subjective and objective image quality score was evaluated.Analyses of the differences between four groups were compared with image quality score as well as organ-specific-radiation dose by single factor variance.Results Radiation dose to brain was conventional group (34.37±3.62),A group (25.91±0.99),B group (23.18±6.11) and C group (17.38 ± 3.23) mSv,respectively.The difference was of statistical significance in the four groups (F=54.51,P＜0.05).Dose to eye lens was conventional group (41.54± 1.04),A group (33.03±0.35),B group (26.18±2.72) and C group (20.88±4.45) mSv,with statistical significance in difference between the four groups (F=189.75,P＜0.05).Dose to salivary gland was conventional group (35.04 ± 4.94),A group (25.92 ± 0.99),B group (22.93 ± 6.54) and C (14.96±2.67) mSv,respectively,with statistical significance in difference between the four groups (F=65.74,P＜0.05).Image quality scores were respectively conventional group (4.97±0.13),A group (4.77 ± 0.49),B group (4.60 ± 0.49) and C group (3.98 ± 0.61),respectively,with statistical significance between them (F=3.89,P＜0.05),but without statistical significance in difference between the four groups (P ＞ 0.05).The signal-to-noise ratios of gray matter in A,B and C groups were conventional group (18.69 ± 3.55),A group (16.76 ± 2.87),B group (15.05 ± 2.80) and C group (13.65±2.53),respectively,without statistical significance in difference between the four groups (P＞ 0.05);The signal-to-noise ratios of white matter in conventional group (17.46±3.72),A group (15.54± 2.81),B group (13.71±2.43) and C group (11.77±2.18),respectively,without statistical significance in difference between the four groups (P＞0.05).Conclusions Adjusting the tube current time product (mAs) according to head circumference index of children and adolescents can make scanning program more personalized and reduce organ-specific-radiation doses to sensitive organs without compromise of image quality.

Objective    To evaluate the safety and efficacy of peripheral cannulation for cardiopulmonary bypass (CPB) in patients with reoperation of congenital heart disease. Methods    The perioperative data of patients with congenital heart disease who underwent reoperation in Fuwai Hospital from 2019 to 2020 were retrospectively collected. They were divided into two groups according to the cannulation methods: a central group and a peripheral group. The prognosis of the patients was analyzed. Results     A total of 80 patients were collected, including 43 patients in the central group, and 37 pateints in the peripheral group. In the central group, the median age was 18 (14, 32) years, and 21 patients were male. The median age of the peripheral group was 16 (10, 27 ) years, and 18 patients were male. The CPB time in the peripheral group was 201 (164, 230) min, which was longer than that in the central group [143 (97, 188 ) min, P<0.001]. The lactate after CPB in the peripheral group was statistically higher than that in the central group [2 (1, 2 ) mmol/L vs. 1 (1, 1) mmol/L, P=0.002]. The dosage of albumin use during CPB in the peripheral group was statistically higher than that in the central group [10 (0, 20) g vs. 0 (0, 0) g, P=0.004]. There was no statistical difference in the postoperative dosage of red blood cells use [0 (0, 2) U vs. 0 (0, 0) U, P=0.117], mechanical ventilation time [14 (11, 19) h vs. 13 (10, 15) h, P=0.296], ICU stay time [43 (23, 80) h vs. 40 (20, 67) h, P=0.237] or postoperative hospital stay time [10 (7, 12) d vs. 8 (7, 10) d, P=778] between the two groups. Conclusion    It’s safe and efficient to establish CPB through peripheral cannulation in patients with complex congenital heart disease undergoing reoperation.