Since the first Oxford Survey of Childhood Cancer\'s results were published, people have become more aware of the risks associated with prenatal exposure from diagnostic x rays. As a result, it has since been the subject of many studies. In this review, the results of recent epidemiological studies are summarized. The current international guidelines for diagnostic x-ray examinations were compared to the review. All epidemiological studies starting from 2007 and all relevant international guidelines were included. Apart from one study that involved rhabdomyosarcoma, no statistically significant associations were found between prenatal exposure to x rays and the development of cancer during 2007-2020. Most of the studies were constrained in their design due to too small a cohort or number of cases, minimal x-ray exposure, and/or data obtained from the exposed mothers instead of medical reports. In one of the studies, computed tomography exposure was also included, and this requires more and longer follow-up in successive studies. Most international guidelines are comparable, provide risk coefficients that are quite conservative, and discourage abdominal examinations of pregnant women.

The meeting held in May 2014 in Würzburg, Germany, discussed the scope of the revision of the 1999 WHO guidelines for iodine thyroid blocking (ITB) by following the WHO handbook for guideline development. This article describes the process and methods of developing the revised, evidence-based WHO guidelines for ITB following nuclear and radiological accidents, the results of the kick-off meeting as well as further steps taken to complete the revision.

This study analyses the efficiency of the justification of individual computed tomography (CT) procedures using the good practice guide. The conformity of the CT scans with guide\'s recommendations was retrospectively analysed in a paediatric emergency hospital in Romania. The involved patient doses were estimated. The results show that around one-third of the examinations were not prescribed in conformity with the guide\'s recommendations, but these results are affected by unclear guide provisions, discussed here. The implications of the provisions of the revised International Atomic Energy Agency\'s Basic Safety Standards and of the Council Directive 2013/59/EURATOM were analysed. The education and training courses for medical doctors disseminating the provisions of the good practice guide should be considered as the main support for the justification of the CT scans at the individual level.

The primary aim of the epidemiologic study of one million U.S. radiation workers and veterans [the Million Worker Study (MWS)] is to provide scientifically valid information on the level of radiation risk when exposures are received gradually over time and not within seconds, as was the case for Japanese atomic bomb survivors. The primary outcome of the epidemiologic study is cancer mortality, but other causes of death such as cardiovascular disease and cerebrovascular disease will be evaluated. The success of the study is tied to the validity of the dose reconstruction approaches to provide realistic estimates of organ-specific radiation absorbed doses that are as accurate and precise as possible and to properly evaluate their accompanying uncertainties. The dosimetry aspects for the MWS are challenging in that they address diverse exposure scenarios for diverse occupational groups being studied over a period of up to 70 y. The dosimetric issues differ among the varied exposed populations that are considered: atomic veterans, U.S. Department of Energy workers exposed to both penetrating radiation and intakes of radionuclides, nuclear power plant workers, medical radiation workers, and industrial radiographers. While a major source of radiation exposure to the study population comes from external gamma- or x-ray sources, for some of the study groups, there is a meaningful component of radionuclide intakes that requires internal radiation dosimetry assessments. Scientific Committee 6-9 has been established by the National Council on Radiation Protection and Measurements (NCRP) to produce a report on the comprehensive organ dose assessment (including uncertainty analysis) for the MWS. The NCRP dosimetry report will cover the specifics of practical dose reconstruction for the ongoing epidemiologic studies with uncertainty analysis discussions and will be a specific application of the guidance provided in NCRP Report Nos. 158, 163, 164, and 171. The main role of the Committee is to provide guidelines to the various groups of dosimetrists involved in the MWS to ensure that certain dosimetry criteria are considered: calculation of annual absorbed doses in the organs of interest, separation of low and high linear-energy transfer components, evaluation of uncertainties, and quality assurance and quality control. It is recognized that the MWS and its approaches to dosimetry are a work in progress and that there will be flexibility and changes in direction as new information is obtained with regard to both dosimetry and the epidemiologic features of the study components. This paper focuses on the description of the various components of the MWS, the available dosimetry results, and the challenges that have been encountered. It is expected that the Committee will complete its report in 2016.

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BACKGROUND: Multifocal papillary thyroid carcinoma (MPTC) has been reported in literature in 18-87 % of cases. This paper aims to review controversies in the molecular pathogenesis, prognosis, and management of MPTC.
METHODS: A review of English-language literature focusing on MPTC was carried out, and analyzed in an evidence-based perspective. Results were discussed at the 2013 Workshop of the European Society of Endocrine Surgeons devoted to surgery of thyroid carcinoma.
RESULTS: Literature reports no prospective randomized studies; thus, a relatively low level of evidence may be achieved.
CONCLUSIONS: MPTC could be the result of either true multicentricity or intrathyroidal metastasis from a single malignant focus. Radiation and familial nonmedullary thyroid carcinoma are conditions at risk of MPTC development. The prognostic importance of multifocal tumor growth in PTC remains controversial. Prognosis might be impaired in clinical MPTC but less or none in MPTC <1 cm. MPTC can be diagnosed preoperatively by FNAB and US, with low sensitivity for MPTC <1 cm. Total or near-total thyroidectomy is indicated to reduce the risk of local recurrence. Prophylactic central node dissection should be considered in patients with total tumor diameter >1 cm, or in cases with high number of cancer foci. Completion thyroidectomy might be necessary when MPTC is diagnosed after less than near-total thyroidectomy. Radioactive iodine ablation should be considered in selected patients with MPTC at increased risk of recurrence or metastatic spread.

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BACKGROUND: Ever since a lung cancer epidemic emerged in the mid-1900 s, the epidemiology of lung cancer has been intensively investigated to characterize its causes and patterns of occurrence. This report summarizes the key findings of this research.
METHODS: A detailed literature search provided the basis for a narrative review, identifying and summarizing key reports on population patterns and factors that affect lung cancer risk.
RESULTS: Established environmental risk factors for lung cancer include smoking cigarettes and other tobacco products and exposure to secondhand tobacco smoke, occupational lung carcinogens, radiation, and indoor and outdoor air pollution. Cigarette smoking is the predominant cause of lung cancer and the leading worldwide cause of cancer death. Smoking prevalence in developing nations has increased, starting new lung cancer epidemics in these nations. A positive family history and acquired lung disease are examples of host factors that are clinically useful risk indicators. Risk prediction models based on lung cancer risk factors have been developed, but further refinement is needed to provide clinically useful risk stratification. Promising biomarkers of lung cancer risk and early detection have been identified, but none are ready for broad clinical application.
CONCLUSIONS: Almost all lung cancer deaths are caused by cigarette smoking, underscoring the need for ongoing efforts at tobacco control throughout the world. Further research is needed into the reasons underlying lung cancer disparities, the causes of lung cancer in never smokers, the potential role of HIV in lung carcinogenesis, and the development of biomarkers.

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OBJECTIVE: The increasing use of computed tomography (CT) has been accompanied by rising concerns over potential radiation-related health risks, especially cancer, and a need to minimize such risks.
METHODS: We conducted 2186 low-dose helical chest CT scans among 1235 nuclear weapons workers at elevated risk of lung cancer, setting the CT scanner tube current at 30 mAs for all participants with BMI <35 kg/m(2) and permitting technologists to raise mAs levels for participants with BMI ≥35 kg/m(2). Dose-length product (DLP) was recorded from the CT scanner, permitting calculation of effective dose. Phantom-based estimates of effective dose were also made. A chest radiologist recorded acceptability of image quality.
RESULTS: The study population was significantly overweight: 79% exceeded a body mass index (BMI) >25 kg/m(2) and 37.1% exceeded a BMI ≥30 kg/m(2). Nearly 90% of CT scans were performed using a tube current setting of 30 mAs and had a mean DLP-based effective dose of 1.3 mSv. The phantom-based estimate of effective dose was lower at 1.1 mSv. Among participants with a BMI ≥35 kg/m(2), 92% were scanned at 40 or 50 mAs, which was associated with a DLP-based effective dose of 1.6 and 2.0 mSv, respectively. Image quality was satisfactory in 99.8% of scans.
CONCLUSIONS: Application of simple BMI-based guidelines and DLP tracking of low-dose helical chest CT scans in a lung cancer screening program minimizes radiation dose, even in a largely overweight population.