The radiographer's perspective on X-ray examinations in potentially pregnant patients; results of a focus group study among Dutch radiographers.

INTRODUCTION: The Netherlands does not have a national guideline for performing radiographic examinations on pregnant patients. Radiographic examination is a generic term for all examinations performed using ionizing radiation, including but not limited to radiographs, fluoroscopy and computed tomography. A pilot study amongst radiographers (Medical Radiation Technologists (MRTs)) showed that standardized practice of radiographic examinations on pregnant women is not evident between Radiology departments and that there is a need for a national guideline as the varying practice methods may lead to confusion and uncertainty amongst both patients and MRTs. METHODS: Focus groups consisting of MRTs from several Radiology departments within the Netherlands were used to map ideas and requirements as to what should be included in the national guideline. Nine focus group sessions were organized with a total of 52 participants. Using a previous review (Wit, Fleur; Vroonland, Colinda; Bijwaard H. Pre-natal X-ray exposure and the risk of developing paediatric cancer; a systematic review of risk factors and a comparison of international guidelines. Health Physics 2021; 121 (3):225-233), the following key points were chosen as discussion topics for the focus group sessions: dose reduction, confirming pregnancy and risk communication. RESULTS: Results showed that the participating MRTs did not agree on the use of lead aprons. That the national guideline should include standardized methods to adjust parameters to decrease radiation dose. Focus group participants find it difficult to ask a patient's pregnancy status, especially when dealing with relatively young and old (er) patients. When communicating the level of risk associated with a radiographic examination the participating MRTs would like to be able to use examples and comparisons, preferably by means of a multilingual website. CONCLUSION: A national guideline must include information on justification, available alternatives, dose reductions methods and confirmation of pregnancy requirements when fetal dose is a significant risk. IMPLICATIONS FOR PRACTICE: A national guideline ensures standardized practice can be implemented in Radiology departments, increasing clarity of the issues for both patients and MRTs.

Analysis of radiation exposure data from common radiological procedures in Dutch hospitals.

INTRODUCTION: In the Netherlands, Diagnostic Reference Levels (DRLs) have not been based on a national survey as proposed by ICRP. Instead, local exposure data, expert judgment and the international scientific literature were used as sources. This study investigated whether the current DRLs are reasonable for Dutch radiological practice. METHODS: A national project was set up, in which radiography students carried out dose measurements in hospitals supervised by medical physicists. The project ran from 2014 to 2017 and dose values were analysed for a trend over time. In the absence of such a trend, the joint yearly data sets were considered a single data set and were analysed together. In this way the national project mimicked a national survey. RESULTS: For six out of eleven radiological procedures enough data was collected for further analysis. In the first step of the analysis no trend was found over time for any of these procedures. In the second step the joint analysis lead to suggestions for five new DRL values that are far below the current ones. The new DRLs are based on the 75 percentile values of the distributions of all dose data per procedure. CONCLUSION: The results show that the current DRLs are too high for five of the six procedures that have been analysed. For the other five procedures more data needs to be collected. Moreover, the mean weights of the patients are higher than expected. This introduces bias when these are not recorded and the mean weight is assumed to be 77 kg. IMPLICATIONS FOR PRACTICE: The current checking of doses for compliance with the DRLs needs to be changed. Both the procedure (regarding weights) and the values of the DRLs should be updated.

Digital imaging and radiographic practise in diagnostic radiography: An overview of current knowledge and practice in Europe.

INTRODUCTION: Recent research has identified the issue of 'dose creep' in diagnostic radiography and claims it is due to the introduction of CR and DR technology. More recently radiographers have reported that they do not regularly manipulate exposure factors for different sized patients and rely on pre-set exposures. The aim of the study was to identify any variation in knowledge and radiographic practice across Europe when imaging the chest, abdomen and pelvis using digital imaging. METHODS: A random selection of 50% of educational institutes (n = 17) which were affiliated members of the European Federation of Radiographer Societies (EFRS) were contacted via their contact details supplied on the EFRS website. Each of these institutes identified appropriate radiographic staff in their clinical network to complete an online survey via SurveyMonkey. Data was collected on exposures used for 3 common x-ray examinations using CR/DR, range of equipment in use, staff educational training and awareness of DRL. Descriptive statistics were performed with the aid of Excel and SPSS version 21. RESULTS: A response rate of 70% was achieved from the affiliated educational members of EFRS and a rate of 55% from the individual hospitals in 12 countries across Europe. Variation was identified in practice when imaging the chest, abdomen and pelvis using both CR and DR digital systems. There is wide variation in radiographer training/education across countries. CONCLUSION: There is a need for standardisation of education and training including protocols and exposure parameters to ensure that there is continued adherence to the ALARA principle.

Compliance to Diagnostic Reference Levels for radiation exposure in common radiological procedures in Dutch hospitals: A nation-wide survey carried out by medical imaging students.

INTRODUCTION: In the Netherlands, hospitals have difficulty in implementing the formal procedure of comparing radiation dose values to Diagnostic Reference Levels (DRLs). METHODS: To support the hospitals, train radiography students, and carry out a nationwide dose survey, diagnostic radiography students performed 125 DRL comparisons for nine different procedures in 29 radiology departments. Students were instructed at three Dutch Universities of Applied Sciences with a radiography programme and supervised by medical physicists from the participating hospitals. RESULTS: After a pilot study in the western part of the country in eight hospitals, this study was enlarged to involve 21 hospitals from all over the Netherlands. The 86 obtained dose comparisons fall below the DRLs in 97% of all cases. This very high compliance may have been enhanced by the voluntary participation of hospitals that are confident about their performance. CONCLUSION: The results indicate that the current DRLs that were not based on a national survey, may need to be updated, sometimes to half their current value. For chest and pelvis examinations the DRLs could be lowered from 12 and 300 µGy·m2 to the 75-percentile values found in this study of 5,9 and 188 µGy·m2, respectively.

Progress in updating the European Radiobiology Archives.

PURPOSE: The European Radiobiology Archives (ERA), together with corresponding Japanese and American databases, hold data from nearly all experimental animal radiation biology studies carried out between 1960 and 1998, involving more than 300,000 animals. The Federal Office for Radiation Protection, together with the University of Cambridge have undertaken to transfer the existing ERA archive to a web-based database to maximize its usefulness to the scientific community and bring data coding and structure of this legacy database into congruence with currently accepted semantic standards for anatomy and pathology. METHODS: The accuracy of the primary data input was assessed and improved. The original rodent pathology nomenclature was recoded to replace the local 'DIS-ROD' (Disease Rodent) formalism with Mouse Pathology (MPATH) and Mouse Anatomy (MA) ontology terms. A pathology panel sampled histopathological slide material and compared the original diagnoses with currently accepted diagnostic criteria. RESULTS: The overall non-systematic error rate varied among the studies between 0.26% and 4.41%, the mean error being 1.71%. The errors found have been corrected and the studies thus controlled have been annotated. The majority of the original pathology terms have been successfully translated into a combination of MPATH and MA ontology terms. CONCLUSIONS: ERA has the potential of becoming a world-wide radiobiological research tool for numerous applications, such as the re-analysis of existing data with new approaches in the light of new hypotheses and techniques, and using the database as an information resource for planning future animal studies. When the database is opened for new data it may be possible to offer long-term storage of data from recent and future animal studies.

Mechanistic models of bone cancer induction by radium and plutonium in animals compared to humans.

Two-mutation carcinogenesis models of mice and rats injected with (239)Pu and (226)Ra have been derived extending previous modellings of beagle dogs injected with (239)Pu and (226)Ra and radium dial painters. In all cases statistically significant parameters could be derived fitting data from several research groups jointly. This also lead to similarly parametrised models for (239)Pu and (226)Ra for all species. For each data set not more than five free model parameters were needed to fit the data adequately. From the toxicity ratios of the animal models for (239)Pu and (226)Ra, together with the human model for (226)Ra, an approximate model for the exposure of humans to (239)Pu has been derived. Relative risk calculations with this approximate model are in good agreement with epidemiological findings for the plutonium-exposed Mayak workers. This promising result may indicate new possibilities for estimating risks for humans from animal experiments.

Analysis of epidemiological cohort data on smoking effects and lung cancer with a multi-stage cancer model.

A stochastic two-stage cancer model is used to analyse the relation between lung cancer and cigarette smoking. The model contains the main rate-limiting stages of carcinogenesis, which include initiation, promotion (clonal expansion of initiated cells), malignant transformation and a lag time for tumour formation. Various data sets were used to test the model. These include the data of a large prospective collaborative project carried out in 10 different European countries, the European Prospective Investigation into Cancer and Nutrition (EPIC). This new data set has not been modelled before. The model is also tested on other published data from CPS-II (Cancer Prevention Study II) of the American Cancer Society and the British doctors' study. The analyses indicate that the EPIC data are best described with smoking dependence on the rates of malignant transformation and clonal expansion. With increasing smoking rates, saturation effects in the two exposure rate-dependent model parameters were observed. The results find confirmation in the biological literature, where both mutational effects and promotional effects of cigarette smoke are documented.

A consistent two-mutation model of bone cancer for two data sets of radium-injected beagles.

A two-mutation carcinogenesis model has been applied to model osteosarcoma incidence in two data sets of beagles injected with 226Ra. Taking age-specific retention into account, the following results have been obtained: (1) a consistent and well-fitting solution for all age and dose groups, (2) mutation rates that are linearly dependent on dose rate, with an exponential decrease for the second mutation at high dose rates, (3) a linear-quadratic dose-effect relationship, which indicates that care should be taken when extrapolating linearly, (4) highest cumulative incidences for injection at young adult age, and highest risks for injection doses of a few kBq kg(-1) at these ages, and (5) when scaled appropriately, the beagle model compares fairly well with a description for radium dial painters, suggesting that a consistent model description of bone cancer induction in beagles and humans may be possible.

The implications of re-analysing radiation-induced leukaemia in atomic bomb survivors: risks for acute and chronic exposures are different.

Implications of risk estimates, as required for practical radiation protection purposes, were explored through a preliminary re-analysis of leukaemia in the Japanese atomic bomb survivors using a biologically based cancer model. The calculations for the risks posed for contracting leukaemia pointed to important differences between low-dose-rate ('chronic') and high-dose-rate ('acute') exposures. For example, the risks caused by long-term ('chronic') exposures are calculated to be substantially lower than those for 'acute' exposures. In view of these model predictions the results of epidemiological studies are discussed.

A consistent two-mutation model of lung cancer for different data sets of radon-exposed rats.

A two-mutation carcinogenesis model, formulated in terms of biologically motivated equations for mutation and expansion steps, has been applied in a mechanistic modelling of the lung cancer incidence in two large data sets of rats exposed to radon, both separately and jointly. Results indicate that (1) the equations employed are able to provide an accurate description of the separate data sets, (2) the parameters in the equations take on similar values for both data sets, and (3) it is possible to construct a consistent and well-fitting solution for the joint data set. It proved not to be necessary to take into account the effect of uranium ore dust, administered to part of the data or the different rat strains of the data sets. The joint solution provides a firm basis to investigate the effects of exposure, exposure rate and age at exposure on cumulative incidence, excess relative risk and excess absolute risk. For the same total exposure, cumulative incidence reaches a maximum for exposure rates between 1 and 10 WLM per day. The so-called inverse-exposure-rate effect acts for higher exposure rates. The influence of age at exposure, however, seems to be even more pronounced. Exposure at a young age leads to considerably higher incidences than exposure at a later age. Parameters derived in this study compare fairly well with those derived for uranium miners, suggesting that a consistent model description for the induction of lung cancer by radon in rats and humans may be possible.

A Lower Mantle Source for Central European Volcanism.

Cenozoic rifting and volcanism in Europe have been associated with either passive or active mantle upwellings. Tomographic images show a low velocity structure between 660- and 2000-kilometer depth, which we propose to represent a lower mantle upwelling under central Europe that may feed smaller upper-mantle plumes. The position of the rift zones in the foreland of the Alpine belts and the relatively weak volcanism compared to other regions with plume-associated volcanism are probably the result of the past and present subduction under southern Europe.