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Objectives The objective of this study was to investigate the feasibility of defining diagnostic reference levels (DRLs) on a European basis for specific clinical indications (CIs), within the context of the European Clinical DRLs (EUCLID) European Commission project. Methods A prospective, multicenter, industry-independent European study was performed to provide data on 10 CIs (stroke, chronic sinusitis, cervical spine trauma, pulmonary embolism, coronary calcium scoring, coronary angiography, lung cancer, hepatocellular carcinoma, colic/abdominal pain, and appendicitis) via an online survey that included information on patient clinical, technical, and dosimetric parameters. Data from at least 20 patients per CI were requested from each hospital. To establish DRLs, a methodology in line with the International Commission on Radiological Protection (ICRP) Report 135 good practice recommendations was followed. Results Data were collected from 19 hospitals in 14 European countries on 4299 adult patients and 10 CIs to determine DRLs. DRLs differ considerably between sites for the same CI. Differences were attributed mainly to technical protocol and variable number of phases/scan lengths. Stroke and hepatocellular carcinoma were the CIs with the highest DRLs. Coronary calcium scoring had the lowest DRL value. Comparison with published literature was limited, as there was scarce information on DRLs based on CI. Conclusions This is the first study reporting on feasibility of establishing CT DRLs based on CI using European data. Resulting values will serve as a baseline for comparison with local radiological practice, national authorities when DRLs are set/updated, or as a guideline for local DRL establishment. Key Points • First study reporting on the feasibility of establishing CT diagnostic reference levels based on clinical indication using data collected across Europe. • Only one-fourth of the hospitals had CT machines less than 5 years old. • Large dose variations were observed among hospitals and CT protocols were quite different between hospitals.

Background In August 2017, the European Commission awarded the “European Study on Clinical Diagnostic Reference levels for X-ray Medical Imaging” project to the European Society of Radiology, to provide up-to-date Diagnostic Reference Levels based on clinical indications. The aim of this work was to conduct an extensive literature review by analysing the most recent studies published and the data provided by the National Competent Authorities, to understand the current situation regarding Diagnostic Reference Levels based on clinical indications for computed tomography. Results The literature review has identified 23 papers with Diagnostic Reference Levels based on clinical indications for computed tomography from 15 countries; 12 of them from Europe. A total of 28 clinical indications for 6 anatomical areas (head, cervical spine/neck, chest, abdomen, abdomen-pelvis, chest-abdomen-pelvis) have been identified. Conclusions In all the six anatomical areas for which Diagnostic Reference Levels based on clinical indications were found, a huge variation of computed tomography dose descriptor values was identified, providing evidence for a need to develop strategies to standardise and optimise computed tomography protocols.

Objective To collect and analyze radiation dose metrics from 23 commonly performed CT procedures, for which no national DRLs have yet been defined, as part of an international cooperation. The body region, the clinical task, and the relevant technical parameters were considered to define clinical diagnostic reference levels (DRLs). Materials and methods During 2022–2023, a multicenter study was performed in Austria, Germany, Italy, and Switzerland. Healthcare providers supplied processed data from their dose management systems. The 5%-level was used to assess the statistical significance of dose differences between the countries of participants, as well as age and manufacturer of the scanners. Results Dose metrics from 87 CT systems in academic and non-academic, public and private healthcare facilities were analyzed. Dose values from the same body region but for different clinical tasks and/or using different techniques might differ significantly. For the same procedures, median dose values varied between systems by a factor of up to 39. Approximately a third of the surveyed systems showed doses within the DRLs suggested in this study, while 6% do not fulfill any DRL. No significant dose differences were observed between systems when comparing age, manufacturer or country. Conclusions In this international study, clinical DRLs were suggested for the first time for many different CT procedures, including dose-intensive procedures such as cerebral perfusion or the CT-guided interventional periradicular therapy. The diversity in protocol optimization is one of the main reasons for dose variations. Establishing the proposed DRLs can help harmonize exposure practice across country borders. Critical relevance statement In this international multicenter study, clinical task-based DRLs were suggested for 23 CT procedures to promote the optimization of the exposure practice, to reduce dose variations among institutions, even across national borders and to strengthen international cooperation among users. Key Points Analysis and differences in exposure practices in 23 different CT examinations in four neighboring European countries. Dose values for the same clinical tasks vary considerably between facilities using the same technology, but on average, not between countries. Establishing diagnostic reference levels helps to harmonize the exposure practice across country borders for frequently performed procedures. Graphical Abstract

Objectives To assess information reflecting radiation dose and define diagnostic reference levels (DRL) on a European basis for four interventional radiology (IR) procedures considering clinical indication, anatomical region, and procedure. Methods A prospective European study was performed to provide data on the IR procedures percutaneous recanalization of iliac arteries, percutaneous recanalization of femoropopliteal arteries, transarterial chemoembolization of hepatocellular carcinoma, and percutaneous transhepatic biliary drainage. Hospitals were asked to complete a questionnaire giving information on procedure, equipment, and protocol. Patient size and weight, experience of the operator graded in number of procedures performed, and complexity level of each procedure were reported. Sixteen hospitals from 13 countries could be surveyed. The percentiles of the kerma-area product, fluoroscopy time, cumulative air kerma at the interventional reference point, and number of images were determined. The impact of equipment, year of installation, and complexity level of the procedure on dose were analyzed. Results DRLs based on clinical indication were defined. Dose values varied considerably within hospitals, between them, and within each subgroup of complexity level. The use of state-of-the-art equipment reduced dose significantly by 52%. Although dose also varied within each subgroup of complexity level, for transarterial chemoembolization of hepatocellular carcinoma and percutaneous transhepatic biliary drainage, dose significantly correlated with complexity. Conclusions This was the first study reporting exposure practice and defining DRLs based on clinical indication for four IR procedures on a European basis. These DRLs can serve as a baseline for comparison with local practice, the study as a guideline for future surveys. Key Points • The use of state-of-the-art angiographic equipment reduces dose significantly. • A significant correlation between radiation dose and complexity level is found. • Dose values vary considerably, both within and between individual hospitals, and within each complexity level of interventional radiology procedure.

Purpose To collect and analyze radiation dose-related data as part of international cooperation; to define diagnostic reference levels (DRL) for 24 X-ray projections in plain radiography (DX) considering anatomical region, clinical task, and procedural technique; and to harmonize the exposure practice across country borders. Methods A multicenter study was performed in Austria, Germany, Italy, and Switzerland in 2022–23 to provide dose-related data. Healthcare facilities were asked to provide processed data from their dose management systems. A 5%-level was used for assessing the statistical significance of dose differences between various groups. Results Dose-related data from 85 radiographic systems in academic and non-academic, public, and private healthcare facilities were analyzed. Dose-related parameters differed significantly for many projections with different clinical tasks and techniques. Dose-related data of the procedures varied by a maximum factor of 16 for the same system, and median dose values also differed between hospitals by a maximum factor of 31. A fifth of the surveyed systems exhibit doses above more than half of the new DRLs defined in this study. Apart from the three reference procedures, no significant dose differences were observed between X-ray systems of different ages, from different manufacturers, or from different countries. Conclusions This is the first survey in which exposure practices were investigated in institutions in different central European countries by establishing clinical DRLs for radiography. The observed dose variations could be explained by different reasons, such as non-optimized dose protocols. The new DRLs help to harmonize the exposure practice across country borders. Key Points Question What is the exposure practice for plain radiography procedures for which no clinical diagnostic reference levels (DRLs) have been defined? Are there differences between countries? Findings The dose for the same clinical task and technique can vary considerably among institutions but, on average, do not significantly differ between neighboring countries in Europe. Clinical relevance In this international multicenter study, clinical DRLs were defined for 24 plain radiography projections to promote the optimization of the exposure practice, to reduce dose variations among institutions even across national borders, and to strengthen international cooperation among users.

We search for frozen water and its processing around young stellar objects (YSOs of class I/II). We try to detect potential, regional differences in water ice evolution within YSOs, which is relevant to understanding the chemical structure of the progenitors of protoplanetary systems and the evolution of solid materials. Water plays an important role as a reaction bed for rich chemistry and is an indispensable requirement for life as known on Earth. We present our analysis of NAOS-CONICA/VLT spectroscopy of water ice at 3um for the TTauri star YLW 16A in the rho-Ophiuchi molecular cloud. We obtained spectra for different regions of the circumstellar environment. The observed absorption profiles are deconvolved with the mass extinction profiles of amorphous and crystallized ice measured in laboratory. We take into account both absorption and scattering by ice grains. Water ice in YLW 16A is detected with optical depths of between tau=1.8 and tau=2.5. The profiles that are measured can be fitted predominantly by the extinction profiles of small grains (0.1um - 0.3um) with a small contribution from large grains (<10%). However, an unambiguous trace of grain growth cannot be found. We detected crystallized water ice spectra that have their origin in different regions of the circumstellar environment of the TTauri star YLW 16A. The crystallinity increases in the upper layers of the circumstellar disk, while only amorphous grains exist in the bipolar envelope. As in studies of silicate grains in TTauri objects, the higher crystallinity in the upper layers of the outer disk regions implies that water ice crystallizes and remains crystallized close to the disk atmosphere where water ice is shielded against hard irradiation.

High-energy irradiation of the circumstellar material might impact the structure and the composition of a protoplanetary disk and hence the process of planet formation. In this paper, we present a study on the possible influence of the stellar irradiation, indicated by X-ray emission, on the crystalline structure of the circumstellar dust. The dust crystallinity is measured for 42 class II T Tauri stars in the Taurus star-forming region using a decomposition fit of the 10 micron silicate feature, measured with the Spitzer IRS instrument. Since the sample includes objects with disks of various evolutionary stages, we further confine the target selection, using the age of the objects as a selection parameter. We correlate the X-ray luminosity and the X-ray hardness of the central object with the crystalline mass fraction of the circumstellar dust and find a significant anti-correlation for 20 objects within an age range of approx. 1 to 4.5 Myr. We postulate that X-rays represent the stellar activity and consequently the energetic ions of the stellar winds which interact with the circumstellar disk. We show that the fluxes around 1 AU and ion energies of the present solar wind are sufficient to amorphize the upper layer of dust grains very efficiently, leading to an observable reduction of the crystalline mass fraction of the circumstellar, sub-micron sized dust. This effect could also erase other relations between crystallinity and disk/star parameters such as age or spectral type.

BackgroundVarious imaging modalities, such as multi-detector computed tomography (CT) and cone beam CT are commonly used in infants for the diagnosis of hearing loss and surgical planning of implantation hearing aid devices, with differing results.ObjectiveWe compared three different imaging modalities available in our institution, including a high-class CT scanner, a mid-class CT scanner and an angiography system with a cone beam CT option, for image quality and radiation exposure in a phantom study.Materials and methodsWhile scanning an anthropomorphic phantom imitating a 1-year-old child with vendor-provided routine protocols, organ doses, surface doses and effective doses were determined for these three modalities with thermoluminescent dosimeters. The image quality was evaluated using the signal difference to noise ratio (SDNR) and the spatial resolution of a line-pair insert in the phantom head. The dose efficiency, defined as the ratio of SDNR and effective dose, was also compared.ResultsThe organ and surface doses were lowest with the high-class CT protocol, but the image quality was the worst. Image quality was best with the cone beam CT protocol, which, however, had the highest radiation exposure in this study, whereas the mid-class CT was in between.ConclusionBased on our results, high-end CT should be used for surgical planning because it has the lowest dose, while the image quality is still sufficient for this purpose. However, if highest image quality is needed and required, e.g., by ENT surgeons, the other modalities should be considered.

Introduction Various studies address discrepancies between guideline recommendations for coronary angiographies and clinical practice. While the issue of the appropriateness of recurrent angiographies was studied focusing on the role of the cardiologist, little is known about individual patients’ histories and the associated radiation exposures. Methods We analyzed all patients with coronary artery disease (CAD) in an academic teaching practice who underwent at least one angiography with or without intervention between 2004 and 2009. All performed angiographies in these patients were analyzed and rated by three physicians for appropriateness levels according to cardiology guidelines. Typical exposure data from the medical literature were used to estimate individual radiation exposure. Results In the cohort of 147 patients, a total of 441 procedures were analyzed: between 1981 and 2009, three procedures were performed per patient (range 1–19) on average. Appropriateness ratings were ‘high/intermediate’ in 71 %, ‘low/no’ in 27.6 % and data were insufficient for ratings in 1.4 %. Procedures with ‘low/no’ ratings were associated with potentially avoidable exposures of up to 186 mSv for single patients. Conclusions Using retrospective data, we exemplify the potential benefit of guideline adherence to decrease patients’ radiation exposures. Key Points • A cohort study of 147 patients showed 27.6 % low appropriateness procedures . • Potentially avoidable radiation exposure cumulated up to about 186 mSv for single patients . • Predisposing factors were prior bypass surgery and first treatment in a tertiary centre. • 7.5 % of the patients received 58 % of the potentially avoidable radiation exposure . • The benefits of guideline adherence in decreasing patient radiation exposure are exemplified .