Objective:To better promote the standardization of public health management in China, and provide evidence for the development and improvement of the standardization strategy and management system in public health field in China.Methods:This paper summarizes and analyzes the information about the standardized management mechanism collected from international organizations related with standardization in public health.Results:The standards in public health varied in different management systems of the international organizations, and there were great differences in organization nature, standard types, application, release, organization structure, standard development principles, advantages, transformation, promotion and implementation, and evaluation.Conclusion:China can benefit from the studying of the working mechanism of the international organization related with standardization in public health to facilitate its own standardization in public health.

X-ray imaging is an important method for the diagnosis of corona virus disease(COVID-19), but there is a risk of nosocomial infection during X-ray imaging diagnosis. By analyzing the process of X-ray imaging diagnosis and the possible infection factors in hospital, Jiangsu province took the lead in issuing the Guideline for the nosocomial infection prevention and control of X-ray imaging diagnosis of COVID-19. This guideline clarifies the basic requirements for controlling infections during X-ray imaging diagnosis, the specific measures for staff protection, disinfection of personnel and places, and the protection and disinfection of subjects, which is instructive for field work. It is worth noting that while focusing on controlling infections, the principle of optimal protection for medical exposure cannot be ignored.

Objective:To screen the indicators of retrospective dose estimation, based on 5 cytogenetic methods to assess the victim followed-up at 4 year after 192Ir radiation accident in Nanjing. Methods:The chromosome aberration (dic + r) assay, cytokinesis block micronucleus (MN) and nucleoplasmic bridge (NPB) assay, fluorescence in situ hybridization (FISH)-based and G banding-based translocation analysis were used to retrospective biological dose estimation. Results:The estimated doses of FISH-based and G banding -based analysis were 1.45 and 1.21 Gy respectively, which was similar to the biological dose estimated short time after the accident. However, the estimated doses by chromosome aberration, micronucleus and nucleoplasmic bridge method were 0.56, 0.45 and 0.41 Gy respectively, which were lower than the corresponding biodose. Correction factors were used to adjust the biodose.Conclusions:In the 4th years after exposure, the estimated biological doses by FISH-based and G banding-based translocation were consistent with the biodose.Therefore, the two methods were suitable for retrospective dose estimation, while correction factors should be considered in chromosome aberration method for retrospective dose estimation.

X-ray imaging is an important method for the diagnosis of corona virus disease(COVID-19), but there is a risk of nosocomial infection during X-ray imaging and diagnosis. By analyzing the process of X-ray imaging & diagnosis and the possible exposure factors in hospital, Jiangsu province took the lead in issuing the guideline for the nosocomial infection prevention and control of COVID-19 during X-ray imaging and diagnosis. This guideline clarifies the basic requirements for controlling infections during X-ray imaging and diagnosis, the specific measures for staff protection, disinfection of personnel and sites, and the protection and disinfection of subjects, which is instructive for on-site work. It is worth noting that while focusing on controlling infections, the principle of optimal protection for medical exposure cannot be ignored.

Objective To survey the frequency of medical X-ray diagnosis and estimate the medical exposure levels of Jiangsu province in 2016,so as to be able to improve effectively the protection against medical radiation exposure.Methods All medical institutions in the province were covered in the survey for their basic medical information by means of census method.Frequencies of diagnostic medical X-ray examination were studied using random sampling method in 31 medical institutions.A linear model was established by number of outpatients number of inpatients,number of staff and number of radiation workers to evaluate the medical examination frequency.Results A total of 9 248 pieces of medical X-ray diagnostic equipment by the end of 2016 in Jiangsu province,including 1 110 CT scanners.The total frequencies of diagnostic medical X-ray examination were estimated to be 911.45 examinations per 1 000 population,covering 239.25 per 1 000 for CT scanning.The number of medical X-ray diagnostic equipment increased by a factor of 0.8 while CT scanners by a factor of 3.6 compared to 1999.Medical X-ray diagnostic frequency raised by a factor of 3.2 while CT frequency by a factor of 15.1 compared with previous data.Conclusions The medical X-ray diagnostic frequencies in Jiangsu province was 1.9 times the value given in the UNSCEAR 2008 Report,close to those in some developed European countries.Compared with the study in 2015,the present study has made greater improvement in sampling technique for selection of hospitals and equipment,frequency estimation method and acquisition of influence factors.Estimates of medical X-ray diagnosis frequency are closer to actual level.Further improvement will be needed for the future survey,so as to further study medical exposure levels and to provide basic information for better patient protection.

Objective: To explore the long-term effects of radiation injury and to provide scientific basis for the evaluation of the effects of ionizing radiation injury by carrying out medical follow-up of patients involved in the " 5.7" radiative source accident in Nanjing in 2014. Methods: Through interviewing and investigating, we inquired about the new disease history of the exposed patients from rehabilitation treatment to medical follow-up peroid. Physical and laboratory examinations were carried out. According to relevant standards, physiological and biochemical indexes such as hematopoietic system, immune system, endocrine system, ophthalmology, circulatory system, digestive system, urinary system and bone mineral density were systematically evaluated, with the long-term effects being evaluated. Results: The patient′s vital signs were good without new diseases. The indexes of hematopoietic system, immune system and endocrine system tended to be normal, the circulatory system, digestive system and urinary system showed degenerative changes, the ophthalmic examination showed visual acuity continue to decline, and bone mineral density examination indicated low bone mass. Conclusions Physiological and biochemical indicators of the patients gradually returned to normal without obvious symptoms of radiation damage. Further medical follow-up observation still needs to continue.

OBJECTIVE: To observe the decay law of chromosome aberrations after 3 years iridium-192 radiation exposure in victims of Nanjing “5.7” radiation accident. METHODS: The peripheral blood of victims was collected 3 years after iridium-192 radiation exposure. The routine chromosome aberration analysis, micronucleus analysis and G-banding karyotype analysis were used to detect the chromosomal instability rate, the binuclear micronucleus rate and the stability distortion rate. A dose reconstruction was carried out based on the distortion results. RESULTS: The aberration frequency of dicentric(dic) and centric rings(r) was 6.5% after 3 years iridium-192 radiation exposure, which decreased to 31.0% at 6 days after exposure(the aberration frequency of dic and r was 21.0%). The estimated biological dose based on the aberration frequency of dic and r was 0.75 Gy, which is about 50.0% of the initial estimated dose(1.52 Gy) at 6 days after exposure. The micronucleus rate of the binuclear lymphocytes was 63.0‰, and the estimated biological dose based on the micronucleus rate was 0.71 Gy, which was similar to the estimated dose of aberration frequency of dic and r. The total frequency of chromosome aberration observed by karyotype analysis of G-bands by trypsin using Giemsa was 41.0%, the stability aberration frequency was 30.0%, and the translocation frequency was 15.0%. The result of dose reconstruction based on the translocation frequency was 1.50-1.89 Gy, which was very close to the initial estimated dose(1.52 Gy). CONCLUSION: The decay of unstable chromosome aberration may be influenced by many factors, more detailed data need to be accumulated to study the decay law. The use of stable chromosomal aberrations, especially translocation frequencies used in dose reconstruction in earlier exposures, is an ideal method.

Objective To explore the dosimetric verification method for absorbed dose and twodimensional dose distribution generated through multi-leaf collimator in radiotherapy.Methods A total of 8 medical accelerators were selected in Jiangsu province.Under 6 MV X-rays with a 5 cm × 5 cm field,the thermoluminescent dosimeter (TLD) and EBT3 radiochromic film (RCF) were used to audit the values calculated by treatment planning system (TPS).RCF was used to verify two-dimensional dose distribution under the 6 MV MLC beams for intensity modulated radiation therapy (IMRT).Results The relative dose deviation was from-1.4％ to 6.8％ for TLD and from-1.8％ to 7.8％ for RCF,with 7 accelerators meeting with the IAEA deviation requirement of ± 5％.The passing rates of two-dimensional dose distribution were between 73.7％ and 97.0％,with 7 accelerators greater than 90％.Conclusions TLD and RCF are feasible and suitable for large-scale verification of IMRT TPS absorbed dose and twodimensional dose distribution.

Objective To study the relationship between the risk of malignant tumor and occupational radiation factor among medical diagnostic X-ray workers in Jiangsu province.Methods The retrospective and prospective cohort studies were adopted to investigate the incidence of cancer.Eligible medical diagnostic X-ray workers from the department of radiology in hospitals were selected and assigned into exposure group,while other medical workers from the departments of Internal Medicine,Ear-NoseThroat (ENT) or Pediatrics who attended work at the same period in the same hospital but not engaged in radiation work were regarded as control group during 1950-2011 in Jiangsu province.We calculated the total person-year and analyzed the relative risk (RR) of malignant tumor using Poisson regression model.Results 7 703 participants (3 961 in exposed group and 3 742 in unexposed group) were recruited and followed up,with a total of 315 309 person years and the lost follow-up rate was 6.92％ (533/7 703).During the follow up period,a total of 819 tumor cases were identified (771 were malignant tumors).We found the significant relationship between the risk of malignant tumor and occupational radiation factor,and the RR of solid cancer and total malignant tumor were 1.31 (95％ CI:1.11-1.55) and 1.33 (95％ CI:1.13-1.57),respectively.In addition,the risk of lung cancer in medical diagnostic X-ray workers was significantly higher than that in control group (RR =1.45,95％ CI:1.00-2.09).Conclusions The incidence risk of lung cancer,solid caner and total malignant tumors in medical diagnostic X-ray workers was significantly higher than that in the control group,which might be associated with occupational exposure to ionizing radiation.

Objective To continue following up the cohort members in Jiangsu province who were the largest subgroup in Chinese medical X-ray workers cohort subgroups on radiation carcinogenesis and analysis the cancer risk of medical X-ray workers which might be induced by chronic low-dose ionizing radiation between 1997 and 2011.Methods A retrospective cohort study was utilized to accumulate data.Epicure was applied to compute cumulative person years (with module of Datab) and relative risk (including 95％ CI) of malignant tumor on exposed group(with module of AMFIT) while the factors such as sex and attained-age were adjusted in the cohort members.Results The 7 708 follow-up members included 3 668 medical X-ray workers.The cumulative person-year in the cohort members was 94 651.2 (1997-2011) and its lost rate was 5.79％.During the follow-up period,441 cases had became cancer patients.The relative risk of all cancers was 1.44 (95％ CI:1.18-1.75),so was the solid cancers.Significant elevated risks of cancer were found on lung (RR =1.95,95％ CI:1.30-2.92),esophagus (RR =3.04,95％ CI:1.20-7.70),lymphoma(RR =2.24,95％ CI:0.67-7.48),leukemia(RR =1.57,95 ％ CI:0.33-7.39),throat (RR =2.47) and thyroid (RR =2.80,95 ％ CI:0.24-32.26) among medical X-ray workers.However,The RR of malignant tumors might not be associated with occupational exposure to ionizing radiation if we considered the lost factors (RR =1.2,95％ CI:0.94-1.46)Conclusions The RR of malignant tumors such as the cancer on lung,esophagus,thyroid among the medical X-ray workers in Jiangsu province were enhanced which might be associated with occupational exposure to ionizing radiation.