Recurrent medical imaging exposures for the care of patients: one way forward.

Medical imaging is both valuable and essential in the care of patients. Much of this imaging depends on ionizing radiation with attendant responsibilities for judicious use when performing an examination. This responsibility applies in settings of both individual as well as multiple (recurrent) imaging with associated repeated radiation exposures. In addressing the roles and responsibilities of the medical communities in the paradigm of recurrent imaging, both the International Atomic Energy Agency (IAEA) and the American Association of Physicists in Medicine (AAPM) have issued position statements, each affirmed by other organizations. The apparent difference in focus and approach has resulted in a lack of clarity and continued debate. Aiming towards a coherent approach in dealing with radiation exposure in recurrent imaging, the IAEA convened a panel of experts, the purpose of which was to identify common ground and reconcile divergent perspectives. The effort has led to clarifying recommendations for radiation exposure aspects of recurrent imaging, including the relevance of patient agency and the provider-patient covenant in clinical decision-making. CLINICAL RELEVANCE STATEMENT: An increasing awareness, generating some lack of clarity and divergence in perspectives, with patients receiving relatively high radiation doses (e.g., ≥ 100 mSv) from recurrent imaging warrants a multi-stakeholder accord for the benefit of patients, providers, and the imaging community. KEY POINTS: • Recurrent medical imaging can result in an accumulation of exposures which exceeds 100 milli Sieverts. • Professional organizations have different perspectives on roles and responsibilities for recurrent imaging. • An expert panel reconciles differing perspectives for addressing radiation exposure from recurrent medical imaging.

Radiation exposure and leukaemia risk among cohorts of persons exposed to low and moderate doses of external ionising radiation in childhood.

BACKGROUND: Many high-dose groups demonstrate increased leukaemia risks, with risk greatest following childhood exposure; risks at low/moderate doses are less clear. METHODS: We conducted a pooled analysis of the major radiation-associated leukaemias (acute myeloid leukaemia (AML) with/without the inclusion of myelodysplastic syndrome (MDS), chronic myeloid leukaemia (CML), acute lymphoblastic leukaemia (ALL)) in ten childhood-exposed groups, including Japanese atomic bomb survivors, four therapeutically irradiated and five diagnostically exposed cohorts, a mixture of incidence and mortality data. Relative/absolute risk Poisson regression models were fitted. RESULTS: Of 365 cases/deaths of leukaemias excluding chronic lymphocytic leukaemia, there were 272 AML/CML/ALL among 310,905 persons (7,641,362 person-years), with mean active bone marrow (ABM) dose of 0.11 Gy (range 0-5.95). We estimated significant (P < 0.005) linear excess relative risks/Gy (ERR/Gy) for: AML (n = 140) = 1.48 (95% CI 0.59-2.85), CML (n = 61) = 1.77 (95% CI 0.38-4.50), and ALL (n = 71) = 6.65 (95% CI 2.79-14.83). There is upward curvature in the dose response for ALL and AML over the full dose range, although at lower doses (<0.5 Gy) curvature for ALL is downwards. DISCUSSION: We found increased ERR/Gy for all major types of radiation-associated leukaemia after childhood exposure to ABM doses that were predominantly (for 99%) <1 Gy, and consistent with our prior analysis focusing on <100 mGy.

Examiner perceptions of the MRCGP recorded consultation assessment for general practice licensing during COVID-19: cross-sectional study.

BACKGROUND: The Recorded Consultation Assessment (RCA) was developed rapidly during the COVID-19 pandemic to replace the Clinical Skills Assessment (CSA) for UK general practice licensing. Our aim was to evaluate examiner perceptions of the RCA. METHODS: We employed a cross-sectional design using a questionnaire survey of RCA examiners with attitudinal (relating to examiners thoughts and perceptions of the RCA) and free text response options. We conducted statistical descriptive and factor analysis of quantitative data with qualitative thematic analysis of free text responses. RESULTS: Overall, 182 of 260 (70%) examiners completed the questionnaire. Responders felt that consultations submitted were representative of the work of a typical GP during the pandemic and provided a good sample across the curriculum. They were also generally positive about the logistic, advisory and other support provided as well as the digital platform. Despite responders generally agreeing there was sufficient information available in video or audio consultations to judge candidates' data gathering, clinical management, and interpersonal skills, they were less confident about their ability to make judgments of candidates' performance compared with the CSA. The qualitative analysis of free text responses detailed the problems of case selection and content, explained examiners' difficulties when making judgments, and detailed the generally positive views about support, training and information technology. Responders also provided helpful recommendations for improving the assessment. CONCLUSION: The RCA was considered by examiners to be feasible and broadly acceptable, although they experienced challenges from candidate case selection, case content and judgments leading to suggested areas for improvement.

Effective doses and risks from medical diagnostic x-ray examinations for male and female patients from childhood to old age.

The consideration of risks from medical diagnostic x-ray examinations and their justification commonly relies on estimates of effective dose, although the quantity is actually a health-detriment-weighted summation of organ/tissue-absorbed doses rather than a measure of risk. In its 2007 Recommendations, the International Commission on Radiological Protection (ICRP) defines effective dose in relation to a nominal value of stochastic detriment following low-level exposure of 5.7 × 10-2Sv-1, as an average over both sexes, all ages, and two fixed composite populations (Asian and Euro-American). Effective dose represents the overall (whole-body) dose received by a person from a particular exposure, which can be used for the purposes of radiological protection as set out by ICRP, but it does not provide a measure that is specific to the characteristics of the exposed individual. However, the cancer incidence risk models used by ICRP can be used to provide estimates of risk separately for males and females, as a function of age-at-exposure, and for the two composite populations. Here, these organ/tissue-specific risk models are applied to estimates of organ/tissue-specific absorbed doses from a range of diagnostic procedures to derive lifetime excess cancer incidence risk estimates; the degree of heterogeneity in the distribution of absorbed doses between organs/tissues will depend on the procedure. Depending on the organs/tissues exposed, risks are generally higher in females and notably higher for younger ages-at-exposure. Comparing lifetime cancer incidence risks per Sv effective dose from the different procedures shows that overall risks are higher by about a factor of two to three for the youngest age-at-exposure group, 0-9 yr, than for 30-39 yr adults, and lower by a similar factor for an age-at-exposure of 60-69 yr. Taking into account these differences in risk per Sv, and noting the substantial uncertainties associated with risk estimates, effective dose as currently formulated provides a reasonable basis for assessing the potential risks from medical diagnostic examinations.

Radiation dose rate effects: what is new and what is needed?

Despite decades of research to understand the biological effects of ionising radiation, there is still much uncertainty over the role of dose rate. Motivated by a virtual workshop on the "Effects of spatial and temporal variation in dose delivery" organised in November 2020 by the Multidisciplinary Low Dose Initiative (MELODI), here, we review studies to date exploring dose rate effects, highlighting significant findings, recent advances and to provide perspective and recommendations for requirements and direction of future work. A comprehensive range of studies is considered, including molecular, cellular, animal, and human studies, with a focus on low linear-energy-transfer radiation exposure. Limits and advantages of each type of study are discussed, and a focus is made on future research needs.

The risk of cancer following high, and very high, doses of ionising radiation.

It is established that moderate-to-high doses of ionising radiation increase the risk of subsequent cancer in the exposed individual, but the question arises as to the risk of cancer from higher doses, such as those delivered during radiotherapy, accidents, or deliberate acts of malice. In general, the cumulative dose received during a course of radiation treatment is sufficiently high that it would kill a person if delivered as a single dose to the whole body, but therapeutic doses are carefully fractionated and high/very high doses are generally limited to a small tissue volume under controlled conditions. The very high cumulative doses delivered as fractions during radiation treatment are designed to inactivate diseased cells, but inevitably some healthy cells will also receive high/very high doses. How the doses (ranging from <1 Gy to tens of Gy) received by healthy tissues during radiotherapy affect the risk of second primary cancer is an increasingly important issue to address as more cancer patients survive the disease. Studies show that, except for a turndown for thyroid cancer, a linear dose-response for second primary solid cancers seems to exist over a cumulative gamma radiation dose range of tens of gray, but with a gradient of excess relative risk per Gy that varies with the type of second cancer, and which is notably shallower than that found in the Japanese atomic bomb survivors receiving a single moderate-to-high acute dose. The risk of second primary cancer consequent to high/very high doses of radiation is likely to be due to repopulation of heavily irradiated tissues by surviving stem cells, some of which will have been malignantly transformed by radiation exposure, although the exact mechanism is not known, and various models have been proposed. It is important to understand the mechanisms that lead to the raised risk of second primary cancers consequent to the receipt of high/very high doses, in particular so that the risks associated with novel radiation treatment regimens-for example, intensity modulated radiotherapy and volumetric modulated arc therapy that deliver high doses to the target volume while exposing relatively large volumes of healthy tissue to low/moderate doses, and treatments using protons or heavy ions rather than photons-may be properly assessed.

Candidate perceptions of the UK Recorded Consultation Assessment: cross-sectional data linkage study.

The Recorded Consultation Assessment (RCA) was rapidly developed to replace the Clinical Skills Assessment (CSA) for UK general practice licencing during COVID-19. We aimed to evaluate candidate perceptions of the RCA and relationships with performance. We conducted a cross-sectional survey of RCA candidates with attitudinal, demographic, and free text response options, undertaking descriptive and factor analysis of quantitative data with qualitative thematic analysis of free text. Binomial regression was used to estimate associations between RCA pass, candidate characteristics and questionnaire responses.645 of 1551 (41.6%) candidates completed a questionnaire; 364 (56.4%) responders permitted linkage with performance and demographic data. Responders and non-responders were similar in exam performance, gender and declared disability but were significantly more likely to be UK graduates (UKG) or white compared with international medical (IMG) or ethnic minority graduates. Responders were positive about the digital platform and support resources. A small overall majority regarded the RCA as a fair assessment; a larger majority reported difficulty collecting, selecting, and submitting cases or felt rushed during recording.Logistic regression showed that ethnicity (white vs minority ethnic: odds ratio [OR] 2.99,95% confidence interval [CI] 1.23, 7.30, p = 0.016), training (UK vs IMG: OR 6.88, 95% CI 2.79, 16.95, p < 0.001), and English as first language (OR 5.11, 0% CI 2.08, 12.56, p < 0.001) were associated with exam success but questionnaire subscales, consultation type submitted, or extent of trainer review were not. The RCA was broadly acceptable but experiences were variable. Candidates experienced challenges and suggested areas for improvement.

Overview of epidemiological studies of nuclear workers: opportunities, expectations, and limitations.

Epidemiological studies of those exposed occupationally to ionising radiation offer an important opportunity to directly check the assumptions underlying the international system of radiological protection against low-level radiation exposures. Recent nuclear worker studies, notably the International Nuclear Workers Study (INWORKS) and studies of the Mayak workforce in Russia, provide powerful investigations of a wide range of cumulative photon doses received at a low dose-rate over protracted periods, and broadly confirm radiation-related excess risks of leukaemia and solid cancers at around the levels predicted by standard risk models derived mainly from the experience of the Japanese atomic-bomb survivors acutely exposed principally to gamma radiation. However, the slope of the dose-response for solid cancers expressed in terms of the excess relative risk per unit dose, ERR/Gy, differs between INWORKS and Mayak, such that when compared with the slope derived from the atomic-bomb survivors, INWORKS does not provide obvious support for the use in radiological protection of a dose and dose-rate effectiveness factor greater than one whereas the Mayak workforce apparently does. This difference could be a chance effect, but it could also point to potential problems with these worker studies. Of particular concern is the adequacy of recorded doses received in the early years of operations at older nuclear installations, such as the potential for 'missed' photon doses. A further issue is how baseline cancer rates may influence radiation-related excess risks. There is scope for a considerable increase in the statistical power of worker studies, with longer follow-up capturing more deaths and incident cases of cancer, and further workforces being included in collaborative studies, but the difficulties posed by dosimetry questions should not be ignored and need to be the subject of detailed scrutiny.

Epidemiological studies of natural sources of radiation and childhood cancer: current challenges and future perspectives.

The empirical estimation of cancer risks in children associated with low-dose ionising radiation (<100 mSv) remains a challenge. The main reason is that the required combination of large sample sizes with accurate and comprehensive exposure assessment is difficult to achieve. An international scientific workshop, 'Childhood cancer and background radiation', organised by the Institute of Social and Preventive Medicine of the University of Bern, brought together researchers in this field to evaluate how epidemiological studies of background radiation and childhood cancer can best improve our understanding of the effects of low-dose ionising radiation. This review summarises and evaluates the findings of these studies with regard to their methodological differences, identifies key limitations and challenges, and proposes ways to move forward. Large childhood cancer registries, such as those in Great Britain, France and Germany, now permit the conducting of studies that should have sufficient statistical power to detect the effects predicted by standard risk models. Nevertheless, larger studies or pooled studies will be needed to investigate disease subgroups. The main challenge is to accurately assess children's individual exposure to radiation from natural sources and from other sources, as well as potentially confounding non-radiation exposures, in such large study populations. For this, the study groups should learn from each other to improve exposure estimation and develop new ways to validate exposure models with personal dosimetry.

Building a job-exposure matrix for early plutonium workers at the Sellafield nuclear site, United Kingdom.

The potential for adverse health effects from internal exposure to Plutonium has been recognised since its discovery in the 1940s. However, in the absence of specific information, potential risks from Plutonium exposure have always largely been controlled through knowledge of radiation exposure risks in general, much of which comes from external radiation exposures. To try to obtain more direct estimates of potential internal exposure risks, epidemiological studies of Plutonium workers need to be conducted. Such epidemiological analyses require individual Plutonium exposure estimates that are as accurate and unbiased as possible. The UK Sellafield workforce includes one of the world's largest cohorts of Plutonium workers, which constitutes, by some considerable margin, the group of workers most comprehensively monitored for internal exposure to this alpha-particle-emitter. However, for several hundred workers employed at the start of Plutonium work at the facility, during the period from 1952 through to 1963, the historical urinalysis results available cannot provide sufficiently accurate and unbiased exposure assessments needed for use in epidemiological studies. Consequently, these early workers have had to be excluded from epidemiological analyses and this has significantly reduced the power of these studies. A promising quantitative methodology to overcome the issue of missing or deficient exposure data, is to use exposure data from other sources to estimate the average exposure a 'typical worker' would have received, and to collate this information for specific occupations and years. This approach is called a Job-Exposure Matrix (JEM). Work on a pilot study to construct a population-specific quantitative JEM for the early Plutonium workers at Sellafield during 1952-1963, for whom reliable urinalysis results do not exist, has shown the potential for a JEM approach to produce more reliable and useful exposure estimates for epidemiological research.

The growing importance of radiation worker studies.

Large radiation worker studies have the potential to provide precise risk estimates for protracted exposure to low-level ionising radiation. Recent worker studies have reported statistically discernible dose-related increased risks of cancer; however, results must be interpreted with care, and occupational radiation doses need to be treated with particular attention.

Fitness to practise sanctions in UK doctors are predicted by poor performance at MRCGP and MRCP(UK) assessments: data linkage study.

BACKGROUND: The predictive validity of postgraduate examinations, such as MRCGP and MRCP(UK) in the UK, is hard to assess, particularly for clinically relevant outcomes. The sanctions imposed on doctors by the UK's General Medical Council (GMC), including erasure from the Medical Register, are indicators of serious problems with fitness to practise (FtP) that threaten patient safety or wellbeing. This data linkage study combined data on GMC sanctions with data on postgraduate examination performance. METHODS: Examination results were obtained for UK registered doctors taking the MRCGP Applied Knowledge Test (AKT; n = 27,561) or Clinical Skills Assessment (CSA; n = 17,365) at first attempt between 2010 and 2016 or taking MRCP(UK) Part 1 (MCQ; n = 37,358), Part 2 (MCQ; n = 28,285) or Practical Assessment of Clinical Examination Skills (PACES; n = 27,040) at first attempt between 2001 and 2016. Exam data were linked with GMC actions on a doctor's registration from September 2008 to January 2017, sanctions including Erasure, Suspension, Conditions on Practice, Undertakings or Warnings (ESCUW). Examination results were only considered at first attempts. Multiple logistic regression assessed the odds ratio for ESCUW in relation to examination results. Multiple imputation was used for structurally missing values. RESULTS: Doctors sanctioned by the GMC performed substantially less well on MRCGP and MRCP(UK), with a mean Cohen's d across the five exams of - 0.68. Doctors on the 2.5th percentile of exam performance were about 12 times more likely to have FtP problems than those on the 97.5th percentile. Knowledge assessments and clinical assessments were independent predictors of future sanctions, with clinical assessments predicting ESCUW significantly better. The log odds of an FtP sanction were linearly related to examination marks over the entire range of performance, additional performance increments lowering the risk of FtP sanctions at all performance levels. CONCLUSIONS: MRCGP and MRCP(UK) performance are valid predictors of professionally important outcomes that transcend simple knowledge or skills and the GMC puts under the headings of conduct and trust. Postgraduate examinations may predict FtP sanctions because the psychological processes involved in successfully studying, understanding and practising medicine at a high level share similar mechanisms to those underlying conduct and trust.

Country of qualification is linked to doctors' General Medical Council performance assessment rate, but is it linked to their clinical competence?

Mehdizah and colleagues recently described the prevalence of General Medical Council regulatory performance assessments by doctors' country of primary medical qualification. This article has caused anger within the UK-international medical community because it identifies graduates of certain countries with significantly raised prevalence.The present article comments on evidence from published Royal College of General Practitioners' data that support these conclusions. However, in an increasingly international age of medical education, the ambiguity of attributions of qualifying from a certain country needs addressing. Some medical students of British nationality, for example, who fail to obtain a place at a UK medical school, train in medical schools abroad, and thus may be identified as international medical graduates.Please see related article: https://bmcmededuc.biomedcentral.com/articles/10.1186/s12909-017-0903-6 .

A restatement of the natural science evidence base concerning the health effects of low-level ionizing radiation.

Exposure to ionizing radiation is ubiquitous, and it is well established that moderate and high doses cause ill-health and can be lethal. The health effects of low doses or low dose-rates of ionizing radiation are not so clear. This paper describes a project which sets out to summarize, as a restatement, the natural science evidence base concerning the human health effects of exposure to low-level ionizing radiation. A novel feature, compared to other reviews, is that a series of statements are listed and categorized according to the nature and strength of the evidence that underpins them. The purpose of this restatement is to provide a concise entrée into this vibrant field, pointing the interested reader deeper into the literature when more detail is needed. It is not our purpose to reach conclusions on whether the legal limits on radiation exposures are too high, too low or just right. Our aim is to provide an introduction so that non-specialist individuals in this area (be they policy-makers, disputers of policy, health professionals or students) have a straightforward place to start. The summary restatement of the evidence and an extensively annotated bibliography are provided as appendices in the electronic supplementary material.

Long-term effects of radiation exposure on health.

Late-onset effects of exposure to ionising radiation on the human body have been identified by long-term, large-scale epidemiological studies. The cohort study of Japanese survivors of the atomic bombings of Hiroshima and Nagasaki (the Life Span Study) is thought to be the most reliable source of information about these health effects because of the size of the cohort, the exposure of a general population of both sexes and all ages, and the wide range of individually assessed doses. For this reason, the Life Span Study has become fundamental to risk assessment in the radiation protection system of the International Commission on Radiological Protection and other authorities. Radiation exposure increases the risk of cancer throughout life, so continued follow-up of survivors is essential. Overall, survivors have a clear radiation-related excess risk of cancer, and people exposed as children have a higher risk of radiation-induced cancer than those exposed at older ages. At high doses, and possibly at low doses, radiation might increase the risk of cardiovascular disease and some other non-cancer diseases. Hereditary effects in the children of atomic bomb survivors have not been detected. The dose-response relation for cancer at low doses is assumed, for purposes of radiological protection, to be linear without a threshold, but has not been shown definitively. This outstanding issue is not only a problem when dealing appropriately with potential health effects of nuclear accidents, such as at Fukushima and Chernobyl, but is of growing concern in occupational and medical exposure. Therefore, the appropriate dose-response relation for effects of low doses of radiation needs to be established.