A summary of UNSCEAR evaluation on medical exposure to ionizing radiation and call for more representative data

The annex A of the United Nations Scientific Committee on the Effects of Atomic Radiation(UNSCEAR)2020/2021 Report presented a comprehensive global estimate of frequencies and doses from medical exposure to ionizing radiation,their distribution and trends for the period 2009-2018.The annex considered four general categories of medical practice using ionizing radiation:(a)diagnostic radiology,including dental radiology and computed tomography,(b)interventional radiology(image-guided interventional procedures),(c)nuclear medicine,and(d)radiation therapy.In the period 2009-2018,about 4.2 billion medical radiological examinations were performed annually,resulting in an annual effective dose of 0.57 mSv per caput.The use of computed tomography has continued to grow and the contribution from interventional radiology has increased rapidly in recent years.The annual number of radionuclide therapy treatments has increased by 60% since the UNSCEAR 2008 Report,while the number of courses of radiation therapy has increased by 22%.Medical exposure remains by far the largest human-made source of radiation exposure to the public.The Committee's evaluation relies on the collection of up-to-date and representative exposure data from all Member States of the United Nations.Future exposure survey should be more relevant and useful and adapted to changing data sources and changing uses of radiation across the world.

Medical Radiation Exposure and Human Carcinogenesis-Genetic and Epigenetic Mechanisms

Ionizing radiation （IR） is a potential carcinogen. Evidence for the carcinogenic effect of IR radiation has been shown after long-term animal investigations and observations on survivors of the atom bombs in Hiroshima and Nagasaki. However, IR has been widely used in a controlled manner in the medical imaging for diagnosis and monitoring of various diseases and also in cancer therapy. The collective radiation dose from medical imagings has increased six times in the last two decades, and grow continuously day to day. A large number of evidence has revealed the increased cancer risk in the people who had frequently exposed to x-rays, especially in childhood. It has also been shown that secondary malignancy may develop within the five years in cancer survivors who have received radiotherapv, because of IR-mediated damage to healthy cells. In this article, we review the current knowledge about the role of medical x-ray exposure in cancer development in humans, and recently recognized epigenetic mechanisms in IR-induced carcinogenesis.

Study on healthcare level and its relationship with medical radiation in China

Objective:To evaluate the health-care level(HCL),one of the most extensively used indicators to assess the level of medical exposure,and its influencing factors in China.Methods:Based on the data from the China Statistical Yearbook of the National Bureau of Statistics and other public documents,HCL was calculated in terms of the number of physicians per head of population throughout the country.Multiple linear regression was used to analyze the association of HCL with main socioeconomic factors,including population size,area,number of administrative divisions and gross domestic product(GDP).Results:Since 2015,there has been at least one physician for every 1,000 people in China on average.However,by 2019,there has yet been one physician for more than 1,000 people in each of two provinces.By 2020,there was at least one physician for every 1,000 people across all 31 provincial-level administrative districts(provinces).The population size and GDP were the influencing factors on HCL,with correlation coefficients of 0.416 and-0.583,respectively.Furthermore,a moderate correlation was found between HCL and the frequency of medical exposure(FME)to ionizing radiation(r=-0.620,P=0.028).Conclusion:There has been at least one physician for every 1,000 people since 2015,but there are great differ-ences between various provinces.HCL as an indicator to evaluate level of medical exposure is warranted further research in China.

An analysis of the status of diagnostic radiology equipment in China

Objective:To analyze the current situation of diagnostic radiology equipment in Chinese mainland and to understand changes in the past 20 years,including gaps with other countries,in order to provide a scientific basis for the government to formulate relevant policies and regulations,and supplement Chinese data for international organizations.Methods:This survey adopted a uniformly designed questionnaire,which was completed by the investigators or the respondents.The survey was distributed to all medical institutions that provided diagnostic radiology services in 31 provinces,autonomous regions,and municipalities,excluding Hong Kong,Macao,Taiwan,and military,China.Results:The survey showed that in the past 20 years,the number of medical institutions and diagnostic radiology equipment per million population in China has increased substantially.Dental radiology equipment increased nine-fold,and mammography equipment and computed tomography scanners showed a nearly five-fold increase.The four types of diagnostic radiology equipment,general diagnostic,fluoroscopic,mammography,and computed tomography,were associated with the population.Dental radiology equipment and bone mineral densitometers were related only to the gross domestic product(GDP).A large gap remains in the diagnostic radiology equipment per million population between China and the equipment of health-care level(HCL)I countries.Conclusions:An imbalance in the number of units of diagnostic radiology equipment per million population was observed in the different regions,China.Various types of diagnostic radiology equipment,especially mammography equipment and computed tomography scanners,need to be deployed to meet the medical needs of different populations.