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Objective Justification is a key principle of radiation protection in medicine: it requires that, among other things, all radiological procedure must provide more benefit than harm. While medical imaging has improved patient care, a substantial fraction of exams is unjustified and does not provide a net benefit. Computed tomography (CT) is used increasingly for imaging asymptomatic people for individual health assessment (IHA). This arises, for example, in some instances of use of CT for coronary artery calcium scoring, early detection of lung and colon cancers, and whole-body surveys. These practices are often performed outside formally organized screening programmes, and the evidence for their benefits and harms is usually weak or absent. They are often not part of established healthcare pathways, arrangements for transferring results from them to the healthcare system are usually absent, and quality assurance programmes are seldom in place. Method WHO organized international workshops in 2014 (Munich), 2016 (Seoul), 2017 (Quebec) and 2018 (Copenhagen), and stakeholders’ feedback was collected. The new International Radiation Basic Safety Standards (BSS) were considered in these deliberations. The BSS require that all radiological procedures on asymptomatic individuals, which are not part of approved health screening programmes, be justified by the practitioners involved, and that the individual presenting be informed of the expected potential benefits, potential harms and limitations. Based on these an international expert group published a paper identifying the issues and options open to policy makers and practitioners. The role of both health authorities and radiation regulators was addressed. Concerns included justification and appropriateness of procedures, safety, quality, process evaluation, optimization, protocols, staff education, training, performance, documentation, mechanisms for integrating the results into established care pathways, ethics and health economics issues, information on benefits, harms and other outcomes to citizens, patients and professionals. Results Structured definitions and descriptions of CT-IHA practices have been developed, described and compared with more formal radiation screening programmes. In addition, these definitions/descriptions are reviewed in the context of more widespread screening activities in medicine and public health. The considerations involved go beyond radiation-induced cancer risks, and the obvious radiation related legal and good practice requirements. They include public health, ethics, over-diagnosis, over-treatment, false positives, false negatives, indeterminate results and incidental findings, among others. A framework is presented to assist policy development by health authorities, radiation protection regulators, and other relevant stakeholders. It provides for improving clinical governance and regulatory compliance. Notable uncertainties are involved in treating both benefits and harms as well as in the overall experience of persons in receipt of CT-IHA, and these are addressed. This paper summarizes the structure and content of the new WHO document.

The increasing worldwide use of paediatric computed tomography (CT) has led to increasing concerns regarding the subsequent effects of exposure to radiation. In response to this concern, the international EPI-CT project was developed to study the risk of cancer in a large multi-country cohort. In radiation epidemiology, accurate estimates of organ-specific doses are essential. In EPI-CT, data collection is split into two time periods--before and after introduction of the Picture Archiving Communication System (PACS) introduced in the 1990s. Prior to PACS, only sparse information about scanner settings is available from radiology departments. Hence, a multi-level approach was developed to retrieve information from a questionnaire, surveys, scientific publications, and expert interviews. For the years after PACS was introduced, scanner settings will be extracted from Digital Imaging and Communications in Medicine (DICOM) headers, a protocol for storing medical imaging data. Radiation fields and X-ray interactions within the body will be simulated using phantoms of various ages and Monte-Carlo-based radiation transport calculations. Individual organ doses will be estimated for each child using an accepted calculation strategy, scanner settings, and the radiation transport calculations. Comprehensive analyses of missing and uncertain dosimetry data will be conducted to provide uncertainty distributions of doses.

Contains fulltext : 165689.pdf (Publisher’s version ) (Open Access) An international expert consultation was convened by the World Health Organization (WHO). The purpose of the meeting was to review the use of CT in examining asymptomatic people. This is often referred to as individual health assessment (IHA). IHA was identified as a global phenomenon unenthusiastically tolerated, and not actively promoted, structured, or regulated in most countries. This paper identifies the state of the art for IHA and some considerations in relation to its justification, in different regions of the world. The outcomes reached include the following: questions around terminology and culture of IHA practice; review of IHA in some countries, regions, and international bodies; dilemmas for participants in IHA; risk communication, education, and training for professions and public; the desirability of guidelines and clinical audit; social, ethical, public health, and resource considerations; and a framework for IHA and regulatory considerations. Three subcategories of examination for asymptomatic individuals were identified: formal screening programs; examinations for which the evidence base or risk profile is incomplete; and opportunistic examinations with little or no evidence or risk profile to suggest they have any merit. The latter challenges the justification principle of radiation protection. In addition, the issue of the costs, direct and indirect, associated with false positives and/or equivocal/incidental findings were highlighted. These and other considerations make it difficult to view some IHA as a bona fide medical activity. To allow it to be viewed as such requires that it be conducted within a robust clinical governance framework that includes regulatory dimensions.

In the summer of 2007 the secondary standard dosimetry laboratory (SSDL) in Norway established a calibration service for reference air-kerma product meter (KAP-meter). The air-kerma area product, P(KA), is a dosimetric quantity that can be directly related to the patient dose and used for risk assessment associated with different x-ray examinations. The calibration of reference KAP-meters at the SSDL gives important information on parameters influencing the calibration factor for different types of KAP-meters. The use of reference KAP-meters calibrated at the SSDL is an easy and reliable way to calibrate or verify the P(KA) indicated by the x-ray equipment out in the clinics.Twelve KAP-meters were calibrated at the SSDL by use of the substitution method at five diagnostic radiation qualities (RQRs).The calibration factors varied from 0.94 to 1.18. The energy response of the individual KAP-meters varied by a total of 20% between the different RQRs and the typical chamber transmission factors ranged from 0.78 to 0.91.It is important to use a calibrated reference KAP-meter and a harmonised calibration method in the P(KA) calibration in hospitals. The obtained uncertainty in the P(KA) readings is comparable with other calibration methods if the information in the calibration certificate is correct used, corrections are made and proper positioning of the KAP-chamber is performed. This will ensure a reliable estimate of the patient dose and a proper optimisation of conventional x-ray examinations and interventional procedures.

Indoor tanning increases skin cancer risk, but the importance of different parts of the UV spectrum is unclear. We assessed irradiance of tanning devices in Norway for the period 1983-2005. Since 1983, all tanning models needed approval before being sold or used. UV Type 3 limits were valid from late 1992 (

Children with shunt-treated hydrocephalus are still followed routinely with frequent head CT scans.To estimate the effective dose, brain and lens doses from these examinations during childhood, and to assess dose variation per examination.All children born between 1983 and 1995 and treated for hydrocephalus between 1983 and 2002 were included. We retrospectively registered the number of examinations and the applied scan parameters. The effective dose was calculated using mean conversion factors from the CT dose index measured free in air, while doses to the lens and brain were estimated using tabulated CT dose index values measured in a head phantom.A total of 687 CT examinations were performed in 67 children. The mean effective dose, lens dose and brain dose to children over 6 months of age were 1.2 mSv, 52 mGy and 33 mGy, respectively, and the corresponding doses to younger children were 3.2 mSv, 60 mGy and 48 mGy. The effective dose per CT examination varied by a factor of 64.None of the children was exposed to doses known to cause deterministic effects. However, since the threshold for radiation-induced damage is not known with certainty, alternative modalities such as US and MRI should be used whenever possible.