Objective To study environmental safety reference standard values of commonly encountered pathogenic microorganisms, and provide the basis for environmental risk assessment of a high-level biosafety laboratory (BSL).Methods Using human exposure dose calculation methods as the basic principle in combination with microbial hazard evaluation methods , an infectious dose calculation model of human exposure to pathogenic microorganisms by breathing was proposed . Based on research on characteristics of commonly encountered pathogenic microorganisms at home and abroad , the environ-mental safety threshold reference standard and environmental risk protection zone for such microorganisms were obtained . Results An the environmental risk assessment standard calculation method for commonly encountered highly pathogenic microorganisms was proposed , and the minimum infectious dose and environmental safety threshold of seven commonly encountered pathogenic microorganisms were obtained , including SARS coronavirus , highly pathogenic avian influenza virus, Mycobacterium tuberculosis, Bacillus anthracis, Yersinia pestis,Francisella tularensis, and epidemic hemorrhagic fever virus.Conclusion The results can be used as a reference standard of infectious aerosols in a high-level BSL for environ-mental risk assessment , laboratory risk control and emergency management .

Objective: To investigate the doseresponse relationship between the risk of elevated blood pressure and body mass index (BMI) in primary and secondary school students in Shibei District, Qingdao, so as to provide a reference for precise interventions of elevated blood pressure. Methods: Statistical analysis was conducted on the health examination data of 92 091 primary and secondary school students in Shibei District, Qingdao, in 2022. Overweight and obesity were assessed using the standards from the Screening for Overweight and Obesity among Schoolaged Children and Adolescents, and blood pressure levels were evaluated using the Reference of Screening for Elevated Blood Pressure among Children and Adolescents Aged 7-18 Years. The relationship between BMI and elevated blood pressure was examined using analysis of variance, Chisquare test, multifactorial Logistic regression, and a combination of restricted cubic spline after data cleaning. Results: Based on the standardized scores under different age and gender, BMI was classified into 5 categories. Compared with the group of BMIZ scores 0-<1, the risk of developing high blood pressure gradually decreased with BMIZ scores (OR=0.55, 0.53, P<0.05). Conversely, the risk of developing high blood pressure increased with increasing BMIZ scores (OR=1.90, 3.71, P<0.05). Stratified analyses showed that BMI was positively associated with elevated blood pressure by gender (male, female), age (aged 7-8, 9-11, 12-14, 15-16), and waisttohip ratio (≤0.83, >0.83) (OR=1.18, 1.19, 1.15, 1.22, 1.19, 1.18, 1.19, 1.18, P<0.01). There were multiplicative interactions between BMI and gender, between BMI and age, between BMI and waisttohip ratio (OR=1.53, 1.08, 2.31, P<0.01). Restricted cubic spline analysis showed that as BMI levels increased, the risk of developing elevated blood pressure showed a nonlinear increasing trend in both the 7yearold and the 10 to 16yearold (χ2=27.56, 10.69, 6.10, 27.26, 18.32, 25.71, 10.53, 6.14, P<0.05). Conclusions The risk of elevated blood pressure in primary and secondary school students increases with BMI, showing a nonlinear doseresponse relationship. The blood pressure should be monitored regularly, and comprehensive and effective measures should be implemented to control elevated blood pressure in children and adolescents.

Objective To explore application of automatic tube current modulation combined with iterative reconstruction in CT scanning ( non-enhanced and enhanced) of neck. Methods A total of 80 patients with CT scanning of neck were randomly divided into test group(n=40, automatic tube current modulation, iterative reconstruction ) and control group ( n = 40, 200 mAs, filtered-back-projection reconstruction ) . Subjective scores and objective evaluation of two groups were evaluated. Evaluation included image noise ( SD ) of thyroid gland, trapezius muscle, sternocleidomastoid muscle, submandibular gland, lateral pterygoid muscle and brain tissue. Effective dose ( E ) was compared. Results The E of non-enhanced and enhanced scanning in test group was lower than that of control group with the statistically significant difference(t = -2. 451, -2. 451, P <0. 05). The subjective scores of non-enhanced and enhanced scanning in test group were higher than those of control group with the statistically significant difference (Z = - 1.969, - 2.056, P < 0.05), while SD of thyroid gland, trapezius muscle, sternocleidomastoid muscle, submandibular gland in test group were lower than that of control group with the statistically significant difference ( t =2. 400,2. 516,2. 120,2. 411,4. 134,4. 674, 2. 711,2. 892, P<0. 05). There were no significant differences in SD of lateral pterygoid muscle, brain tissue of non-enhanced and enhanced scanning between two groups (P>0. 05). Conclusions Automatic tube current modulation combined with iterative reconstruction in CT scanning of neck could improve image quality, and reduce effectively radiation dose.

Objective To explore the influence of iterative algorithm on image quality in ultralow-dose CT scan of lung.Methods The thoracic model was scanned using different parameter combinations.The tube voltage was chose with 80,100 kV in ultra-low dose group and the mAs was selected by 10,15,20,25 and 30 mAs.The control group selected the parameters of 120 kV,30 mAs.All the images were reconstructed with filtered back projection (FBP group) and iterative algorithm (IR group).The image noise and effective dose (E) were compared.Results When tube current and voltage were constant,the image noise of IR group was lower than that of FBP group,and the difference was statistically significant (t =1.102-8.070,P＜0.05).When the tube current was constant,the image noise of the 80 kV with FBP group was higher than that of 100 kV with FBP group,and the image noise of the 80 kV with IR group was lower than the 100 kV with FBP group(t =-8.639-7.841,P＜0.05).Compared with the conventional low-dose with FBP group,the image noise of each ultra-low-dose with FBP group was significantly increased,and the image noise of (80 kV,10 mAs),(80 kV,15 mAs),(80 kV,20 mAs) with IR group was significantly increased,and the image noise of (100 kV,15 mAs),(100 kV,20 mAs),(100 kV,25 mAs),(100 kV,30 mAs) with IR group was significantly reduced (t=-8.140-23.028,P＜0.05).There was no significant difference in image noise between the groups of (80 kV,25 mAs),(80 kV,30 mAs),(100 kV,10 mAs) with IR and the group of conventional low dose with FBP (P＞0.05).Compared with the conventional low dose group,the E of the groups of (80 kV,25 mAs),(80kV,30mAs),(100kV,10 mAs),(100kV,15mAs),(100kV,20mAs),(100kV,25 mAs),(100 kV,30 mAs) was decreased by 75.9％,71.0％,79.8％,70.4％,60.3％,50.2％,40.0％,respectively.Conclusions The image quality of the ultra-low dose protocol (100 kV,10mAs) with iterative algorithm is similar to that of the conventional low dose with FBP group,and the radiation dose could be significantly reduced.

Objective To investigate the effect of CareDose 4D combined with Care kV on CT pulmonary ground glass nodule ( GGN) with respect to quality and radiation dose. Methods The thoracic model containing 6 GGN was performed by using 7 low-dose schemes. The CareDose 4D + Care kV was adopted in scheme 1. In schemes 2, 3 and 4, the tube voltage was 120 kV, and the tube current 30, 20 and 10 mAs respectively. In schemes 5, 6 and 7, the tube voltage was 100 kV, and the tube current was 30, 20 and 10 mAs, respectively. The image quality [ CT value, contrast noise ratio ( CNR) , noise value (SD) and subjective score] and effective dose (E) were compared. Results There was no statistically significant difference in CT value of GGN among different schemes (P>0. 05). The SD of scheme 1 was higher than those of schemes 2, 3 and 5, but lower than those f scheme 7, while the CNR of scheme 1 was lower than those of schemes 2, 3 and 5, but higher than that of scheme 7 ( t=13. 020, 9. 560, 8. 120,-5. 720, -7. 849, -5. 192, -4. 130, 1. 361,P<0. 05). SD and CNR of scheme 1 were not significantly different from those of scheme 4 and 6 ( P>0. 05) . The subjective scores of each GGN of schemes 1, 2, 3, 5 and 6 was over 3 points, but and the subjective scores of one GGN of each of schemes 4 and 7 were below 3 points. The value E of the scheme 1 was reduced by 63. 0％, 44. 4％, 38. 8％, and 9. 1％, compared with the schemes 2, 3, 5 and 6, respectively. Conclusions CareDose 4D combined with Care kV in low-dose lung CT scan can ensure the image quality of GGN and reduce the radiation dose effectively.