NOTE The report of the Committee without its annexes appears as Official Records of the General Assembly, Sixty-third Session, Supplement No. 46. The designations employed and the presentation of material in this publication do not imply the expression of any opinion whatsoever on the part of the Secretariat of the United Nations concerning the legal status of any country, territory, city or area, or of its authorities, or concerning the delimitation of its frontiers or boundaries. The country names used in this document are, in most cases, those that were in use at the time the data were collected or the text prepared. In other cases, however, the names have been updated, where this was possible and appropriate, to reflect political changes. Scientific Annexes Annex A. Medical radiation exposures Annex B. Exposures of the public and workers from various sources of radiation INTROdUCTION 1. In the course of the research and development for and the application of atomic energy and nuclear technologies, a number of radiation accidents have occurred. Some of these accidents have resulted in significant health effects and occasionally in fatal outcomes. The application of technologies that make use of radiation is increasingly widespread around the world. Millions of people have occupations related to the use of radiation, and hundreds of millions of individuals benefit from these uses. Facilities using intense radiation sources for energy production and for purposes such as radiotherapy, sterilization of products, preservation of foodstuffs and gamma radiography require special care in the design and operation of equipment to avoid radiation injury to workers or to the public. Experience has shown that such technology is generally used safely, but on occasion controls have been circumvented and serious radiation accidents have ensued. 2. Reviews of radiation exposures from accidents have been presented in previous UNSCEAR reports. The last report containing an exclusive chapter on exposures from accidents was the UNSCEAR 1993 Report [U6]. 3. This annex is aimed at providing a sound basis for conclusions regarding the number of significant radiation accidents that have occurred, the corresponding levels of radiation exposures and numbers of deaths and injuries, and the general trends for various practices. Its conclusions are to be seen in the context of the Committee's overall evaluations of the levels and effects of exposure to ionizing radiation. 4. The Committee's evaluations of public, occupational and medical diagnostic exposures are mostly concerned with chronic exposures of …

sources and effects of ionizing radiation

OBJECTIVE. In light of the rapidly increasing frequency of pediatric CT examinations, the purpose of our study was to assess the lifetime cancer mortality risks attributable to radiation from pediatric CT.MATERIALS AND METHODS. Organ doses as a function of age-at-diagnosis were estimated for common CT examinations, and estimated attributable lifetime cancer mortality risks (per unit dose) for different organ sites were applied. Standard models that assume a linear extrapolation of risks from intermediate to low doses were applied. On the basis of current standard practice, the same exposures (milliampere-seconds) were assumed, independent of age.RESULTS. The larger doses and increased lifetime radiation risks in children produce a sharp increase, relative to adults, in estimated risk from CT. Estimated lifetime cancer mortality risks attributable to the radiation exposure from a CT in a 1-year-old are 0.18% (abdominal) and 0.07% (head)—an order of magnitude higher than for adults—although those figures st...

https://www.ajronline.org/doi/pdf/10.2214/ajr.176.2.1760289

Estimated Risks of Radiation-Induced Fatal Cancer from Pediatric CT

Medical uses of radiation have grown very rapidly over the past decade, and, as of 2007, medical uses represent the largest source of exposure to the U.S. population. Most physicians have difficulty assessing the magnitude of exposure or potential risk. Effective dose provides an approximate indicator of potential detriment from ionizing radiation and should be used as one parameter in evaluating the appropriateness of examinations involving ionizing radiation. The purpose of this review is to provide a compilation of effective doses for radiologic and nuclear medicine procedures. Standard radiographic examinations have average effective doses that vary by over a factor of 1000 (0.01-10 mSv). Computed tomographic examinations tend to be in a more narrow range but have relatively high average effective doses (approximately 2-20 mSv), and average effective doses for interventional procedures usually range from 5-70 mSv. Average effective dose for most nuclear medicine procedures varies between 0.3 and 20 mSv. These doses can be compared with the average annual effective dose from background radiation of about 3 mSv.

Effective Doses in Radiology and Diagnostic Nuclear Medicine: A Catalog

Risk of cancer from diagnostic X-rays: estimates for the UK and 14 other countries.

Sources, Effects and Risks of Ionizing Radiation

Revised radiation doses for typical X-ray examinations. Report on a recent review of doses to patients from medical X-ray examinations in the UK by NRPB. National Radiological Protection Board.

In 1992 NRPB established a National Collation Centre for measurements of doses to patients made by x-ray departments throughout the UK. This report is the second in a series of five-yearly reviews of the national patient dose database and analyses the information collected during the period January 1996 to December 2000. It includes the results of 28,000 entrance surface dose (ESD) measurements and 13,000 dose-area product (DAP) measurements for single radiographs, and 140,000 DAP measurements and 128,000 records of the fluoroscopy time for complete examinations, collected from 371 hospitals throughout the UK. Information on the patient dose distributions and exposure conditions for over 30 types of examination and radiograph is presented. National reference doses based on the rounded third quartile values of these dose distributions are recommended and are seen to be about 20% lower than corresponding values in the previous (1995) review. They have approximately halved since the original UK national reference doses were derived from a survey in the mid-1980s. In this review reference doses have been derived for a larger number of examinations on adults than previously and, for the first time, for three examinations on children, with specific values for five standard-sized patients corresponding to new born babies, 1, 5, 10 and 15 year olds. NRPB gratefully acknowledges the co-operation of hospital physicists and radiology department staff in supplying patient dose data. The continued provision of data to the National Patient Dose Database will be essential in order to monitor the progress of patient dose reduction measures in the UK and to extend and revise national reference doses in the future.

Doses to Patients from Medical X-ray Examinations in the UK - 2000 Review

Monte Carlo simulations of CT examinations have been performed to estimate effective doses, normalized to axial air kerma, for six mathematical phantoms representing ages from newborn to adult, and for three CT scanner models covering a range of designs. Organ doses were calculated for CT exposures of contiguous, 1 cm wide, transverse slices in each phantom and summed to give normalized effective doses for scans of four regions of the trunk and head. In all cases an inverse trend is observed between normalized effective dose and phantom age, with the dose to the newborn from head and neck scans being 2.2-2.5 times higher than that to the adult, depending on scanner model. Corresponding increases for scans of the trunk region are more variable between scanners and range from a factor of 1.3 to 2.4. If typical clinical exposure conditions for adults are also utilized for children, then, for example, the effective dose to the newborn from a chest scan could be above 15 mSv. It is concluded that CT has the potential to deliver significantly greater radiation doses to children than to adults and in view of their greater susceptibility to radiation effects, special efforts should be made in clinical practice to reduce doses to children by the use of size-specific scan protocols.

Influence of patient age on normalized effective doses calculated for CT examinations.

The National Patient Dose Database (NPDD) is maintained by the Radiation Protection Division of the Health Protection Agency. The latest review of the database analysed the data collected from 316 hospitals over a 5-year period to the end of 2005. The information supplied amounted to a total of 23 000 entrance surface dose measurements and 57 000 dose-area product measurements for single radiographs, and 208 000 dose-area product measurements along with 187 000 fluoroscopy times for diagnostic examinations or interventional procedures. In addition, patient dose data for dental X-ray examinations were included for the first time in the series of 5-yearly reviews. This article presents a summary of a key output from the NPDD - national reference doses. These are based on the third quartile values of the dose distributions for 30 types of diagnostic X-ray examination and 8 types of interventional procedure on adults, and for 4 types of X-ray examination on children. The reference doses are approximately 16% lower than the corresponding values in the previous (2000) review, and are typically less than half the values of the original UK national reference doses that were derived from a survey in the mid-1980s. This commentary suggests that two of the national reference doses from the 2000 review be retained as diagnostic reference levels because the older sample size was larger than for the 2005 review. No clear evidence could be found for the use of digital imaging equipment having a significant effect on dose.

https://www.birpublications.org/doi/pdf/10.1259/bjr/12568539

B. F. Wall

Papers

Revised radiation doses for typical X-ray examinations. Report on a recent review of doses to patients from medical X-ray examinations in the UK by NRPB. National Radiological Protection Board.

Doses to Patients from Medical X-ray Examinations in the UK - 2000 Review

Influence of patient age on normalized effective doses calculated for CT examinations.

National reference doses for common radiographic, fluoroscopic and dental X-ray examinations in the UK

Doses to patients from radiographic and fluoroscopic X-ray imaging procedures in the UK. 2005 review.