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.

A summary of UNSCEAR evaluation on occupational exposure to ionizing radiation and call for more representative data in broader range of occupational sectors

The annex D of the United Nations Scientific Committee on the Effects of Atomic Radiation(UNSCEAR)2020/2021 Report presented a comprehensive global estimate of occupational exposure to ionizing radiation.The worldwide annual number of workers exposed to natural and human-made sources of ionizing radiation was estimated to be approximately 24 million in the period 2010-2014.About 52% of those were employed in the sectors that involve exposure to natural sources of radiation.The worldwide average annual effective dose for all workers during the period 2010-2014 was estimated to be around 1.2 mSv-about two thirds of the value estimated for the period 1995-1999.The annual effective dose was estimated to be around 2.0 mSv for workers exposed to natural sources and 0.5 mSv for workers exposed to human-made sources.The overriding limitation of current evaluation was the low rate of participation by United Nations Member States in providing occupational exposure monitoring data,especially data from non-nuclear sectors and occupational sectors involving naturally occurring radioactive materials.As the assessment of the worldwide occupational exposure is a complex task,the Committee relies on the collection of up-to-date data on occupational exposure from United Nations Member States in a broad range of occupational sectors,and continues collaboration with international organizations.

Performance evaluation of anti-radiation based on the gamma degradation process

In the environment of space radiation, the high-energy charged particles or high-energy photons acting on a spacecraft can cause either temporary device degradation or permanent failure. The traditional probability model is difficult to obtain reliable estimation of unit radiation resistance performance with small samples. Considering that different products will change differently after high-energy particle radiation, we construct a model based on the gamma degradation process. This model can efficiently describe the law of unit radiation resistance variation with the total radiation dose levels under the effect of the total dose and displacement damage. Finally, the proposed model is used to assess the anti-radiation performance of the N-channel power MOSFET device STRH60N20FSY3 produced by STM to obtain average unit radiation resistance, survival probability, survival function, etc.