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To examine the impact of patient size on dose indices and develop size-based reference levels (50th and 75th percentiles) for 20 body CT exams for routine and organ-specific clinical indications.Based on effective diameter estimated from adult body CT, each acquisition was classified into T-shirt size as XXS, XS, S, M, L, XL, and XXL. Radiation dose indices for each size and each exam type were correlated.About 0.93 million CT exams from 256 CT facilities in the United States were analysed. Taking T-shirt size M as a reference, the CTDIA novel approach expressing body habitus in terms of T-shirt size is not only simple and intuitive, but it also provides a tool to have a perception of differences in dose metrices among patients of different body build.

Purpose To present details about the innovative and disruptive technology of monochromatic X-rays and its application to breast imaging. Methods To analyze results of studies done using a prototype system for breast imaging that generates monochromatic X-rays through fluorescence emission. To assess signal-to-noise ratio (SNR) as a measure of image quality at different doses in breast phantoms of different sizes and review the comparison of parameters with a standard mammography system. Results Monochromatic X-rays reduce the radiation dose per mammogram by a factor of 5 to 10 times. For phantom simulating thick breast (9 cm), the SNR for monochromatic system was 2.6 times higher and the dose 4.2 times lower than the respective values obtained with the conventional system within the same 5 mm × 5 mm square area of the 100% glandular step wedge. For the conventional broadband system to equal the SNR of the monochromatic system, it would require a dose of 19 mGy, 29 times higher than the dose delivered by the monochromatic system. Contrast-enhanced digital mammography with monochromatic X-rays is shown to provide a simpler and more effective technique at substantially lower radiation dose. Conclusions Lowering radiation dose by a factor of 5 to 10 while maintaining image quality implies a major reduction in total exposure from breast cancer screening and dramatically less risk of radiation-induced cancers in at-risk women. The high SNRs for very thick breast phantoms provide strong evidence that screening with lower breast compression is possible while maintaining image quality.

Purpose To investigate retrospective classification of adult patients into small, average, and large based on effective diameter (EDia) from localizer image of computed tomography (CT) scans and to develop regional diagnostic reference levels (DRLs) and achievable doses (AD). Method The patients falling within the mean ± standard deviation (SD) of EDia were classified as average; those below this range as small and above as large. The CTDIvol, dose-length-product (DLP) and size-specific dose estimates (SSDE) of all adult patients undergoing CT examinations in 8 CT facilities for 11 months (Dec. 2019 - Oct. 2020) were evaluated. The 75th and 50th percentile values were compared with national and international values. Results Of the total of 69,434 CT examinations, nearly 80% fell within average size. The 75th percentile values of CTDIvol and DLP for small patients for abdomen-pelvic exams were nearly half of average sized patients. Similarly, the 75th percentile values for large patients were nearly double. Similar findings were not found for chest exams. Analysis of image quality and dose factors such as noise, mean axial length, slice thickness, mean number of sequences, use of iterative reconstruction and tube current modulation (TCM) resulted in identification of opportunities for improvement and optimization of different CT facilities. Conclusions DRLs for adult patients were found to vary widely with patient size and thus establishing DRLs only for standard sized patient is not adequate. Simplified and intuitive methods for size classification was shown to provide meaningful information for optimization for patients outside the standard size adult.

Purpose To estimate percentage of patients undergoing multiple CT exams leading to cumulative effective dose (CED) of more than 25, 50, 75 and 100 mSv in one year and assess per capita and the collective effective dose. Methods Data from a regional hospital network was collected retrospectively using radiation dose monitoring system at 6 facilities with 8 CT scanners. The data was analyzed to find number of patients in different dose groups, their age, gender, number of CT exams and exams needed to reach 100 mSv based on age groups. Results In one year 43,010 patients underwent 75,252 CT examinations. The number of exams per 1000 population was 153. Further 27% of the patients were younger than 55- years and 15.9% of them were younger than 45-year-old. A total of 0.67% of patients received a CED > 100 mSv; 3.5% had CED > 50 mSv, 11.9% with CED > 25 mSv and the maximum CED was 529 mSv. The minimum time to reach 100 mSv was a single CT exam. Seven patients received > 100 mSv in a single CT exam. 0.36% of patients had 10 or more CT exams in one year and 3.8% had 5 or more CT exams. The mean CED was 12.3 mSv, the average individual effective dose was 1.1 mSv and the collective effective dose was 521.3 person-Sv. Conclusions The alarming high CED received by large number of patients and with high collective dose to population requires urgent actions by all stake holders in the best interest of patient radiation safety.

To estimate cumulative organ doses and age- and gender-stratified cancer mortality risks in patients undergoing recurrent computed tomography (CT) exams.Cohorts of patients who received cumulative effective dose ≥ 100 mSv were stratified into age and gender groups. Organ doses of 27 organs using Monte Carlo methods were available, and the relative risk model from the Biological Effects of Ionizing Radiation VII (BEIR VII) was used to estimate lifetime attributable cancer mortality risks (LACMR).Out of the 8956 patients, 6.7% were 16-44 years of age, with median organ doses higher than 200 mGy for stomach and liver, whereas organ doses for nine organs, which included lungs, breasts, colon, red bone marrow, urinary bladder, esophagus, testicles, ovaries, and skin were between 100 and 200 mGy. Thyroid and salivary glands had smaller doses in the range of 45-69 mGy, but the mean dose for each organ was over 100 mGy. The age- and gender-specific median LACMR for the 16-44-years cohort was 0.6 to 0.7 deaths per 100 individuals for males, and 0.8 for females. The mortality estimated figures were highest for patients 16-54 years with slightly lower values for older age groups. Except for the highest age bracket of 75-84 years, the LACMR values for 55-74 years are not lower by orders of magnitude, and thus one cannot ignore risks in this age group.Organ doses over 100 mGy for most organs and for some organs ≥ 200 mGy with unignorable associated lifetime attributable cancer mortality rates were found.

Purpose: The objective is to study mammography practice from an optimisation point of view by assessing the impact of simple and immediately implementable corrective actions on image quality. Materials and methods: This prospective multinational study included 54 mammography units in 17 countries. More than 21,000 mammography images were evaluated using a three-level image quality scoring system. Following initial assessment, appropriate corrective actions were implemented and image quality was re-assessed in 24 units. Results: The fraction of images that were considered acceptable without any remark in the first phase (before the implementation of corrective actions) was 70% and 75% for cranio-caudal and medio-lateral oblique projections, respectively. The main causes for poor image quality before corrective actions were related to film processing, damaged or scratched image receptors, or film-screen combinations that are not spectrally matched, inappropriate radiographic techniques and lack of training. Average glandular dose to a standard breast was 1.5mGy (mean and range 0.59-3.2 mGy). After optimisation the frequency of poor quality images decreased, but the relative contributions of the various causes remained similar. Image quality improvements following appropriate corrective actions were up to 50 percentage points in some facilities. Conclusions: Poor image quality is a major source of unnecessary radiation dose to the breast. An increased awareness of good quality mammograms is of particular importance for countries that are moving towards introduction of population-based screening programmes. The study demonstrated how simple and low-cost measures can be a valuable tool in improving of image quality in mammography. (C) 2011 Elsevier Ireland Ltd. All rights reserved.

Purpose: To investigate status of imaging technology and practice in five countries in Eastern-European region (Bosnia and Herzegovina, Croatia, FYR of Macedonia, Montenegro and Serbia) and evaluate the impact of IAEA projects on radiation protection of patients. Method: Information collected included: status of technology used in diagnostic radiology as age of units, type of generators, availability of CT units, mammography units, and digital imaging equipment, use of fluoroscopy for positioning, photofluorography, chest fluoroscopy, radiography technique, CT protocols used and patterns of dealing with pregnancy in diagnostic radiology. Using standardized IAEA protocol for dose measurements, patient doses in interventional procedure, conventional radiography, mammography and Ct were assessed. Results: In diagnostic radiology, the number of digital units is increasing, but single phase generators or units older than 30 year are still in use (more than 40% in some countries). Obsolete practice of use of fluoroscopy for positioning, photofluorography, chest fluoroscopy and soft-beam technique for chest radiography is occasionally or regularly in use. On the other hand, modern units such as mulitislice CT or digital mammography are available in all participating countries, however, adult CT protocol is still in use for examination of children and there is lack of adequate medical physics support in hospitals. In two countries, the awareness of pregnancy issues following exposure and necessity for termination is not adequate. Results on patient dose measurements in interventional radiology, conventional radiography, mammography and CT as a first efforts to reflect the actual practice in the participating countries, were in line with similar studies in other countries, however, dose variation indicated a significant scope for optimization. Based on dose measurement results, points were optimisation is needed were identified, corrective measures proposed and appropriate follow up actions were taken. Conclusions: The IAEA project was a learning process and experience for all participants. The work helped in creating awareness of radiation protection issues and initiation of actions to improve the situation of radiation protection in diagnostic and interventional radiology in all participating countries.

Medical application of ionizing radiation is a massive and increasing activity globally. While the use of ionizing radiation in medicine brings tremendous benefits to the global population, the associated risks due to stochastic and deterministic effects make it necessary to protect patients from potential harm. Current issues in radiation protection of patients include not only the rapidly increasing collective dose to the global population from medical exposure, but also that a substantial percentage of diagnostic imaging examinations are unnecessary, and the cumulative dose to individuals from medical exposure is growing. In addition to this, continued reports on deterministic injuries from safety related events in the medical use of ionizing radiation are raising awareness on the necessity for accident prevention measures. The International Atomic Energy Agency is engaged in several activities to reverse the negative trends of these current issues, including improvement of the justification process, the tracking of radiation history of individual patients, shared learning of safety significant events, and the use of comprehensive quality audits in the clinical environment.