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To evaluate if real-time dose visualisation during computed tomography (CT)-guided interventions leads to a reduction in radiation dose to participating radiologists. The individual radiation dose radiologists are exposed to during CT interventions was measured using dedicated dosimeters (RaySafe i2-system, Unfors RaySafe GmbH, Billdal, Sweden) worn over the usual radiation protective apron. Initially, only the total radiation dose was measured, without visualisation (control group). In the following study period, the radiation dose was shown to participants on a live screen in real-time (experimental group). In both groups, the dose was recorded in 1-second intervals. The results collected were evaluated by comparison using descriptive statistics and mixed-effect models. In particular, the variables experience, gender, role, and position during the intervention were analysed. In total, 517 measurements of 304 interventions (n= 249 with and n= 268 without live screen) performed by 29 radiologists acting as interventionalists or assistants were analysed. All CT-guided interventions were performed percutaneously, the majority of which (n= 280) were microwave ablations (MWA). Radiation doses in the group without visualisation were comparable with usual dose rates for the corresponding intervention type. The mean total radiation dose was reduced by 58.1% (11.6 versus 4.86 μSv) in the experimental group (p= 0.034). The highest reduction of 78.5% (15.55 versus 3.35 μSv) was observed in radiologists with the role of assistant (p= 0.002). Sub-analysis showed significant dose reduction (p< 0.0001) for the use of live screen in general; considering all variables, the role "assistant" alone had a statistically significant influence (p= 0.002). The real-time visualisation of active radiation dose during CT interventions leads to a relevant reduction in radiation dose to participating radiologists. • Real-time dose visualisation leads to dose reduction on participating radiologists. • Most significant dose reduction was seen in radiologists in the role of "assistant". • Interventionalist's experience influences active radiation dose during interventions. [ABSTRACT FROM AUTHOR]

Objectives: To assess cumulative effective dose (CED) over a 4-year period in patients undergoing multimodality recurrent imaging at a major hospital in the USA. Methods: CED from CT, fluoroscopically guided intervention (FGI), and nuclear medicine was analyzed in consecutive exams in a tertiary care center in 2018–2021. Patients with CED ≥ 100 mSv were classified by age and body habitus (underweight, healthy weight, overweight, obese), as per body mass index percentiles < 5th, 5th to < 85th, 85th to < 95th, and ≥ 95th (age 2–19 years), and its ranges < 18.5, 18.5–24.9, 25–29.9, and ≥ 30 (≥ 20 years), respectively. Results: Among a total of 205,425 patients, 5.7% received CED ≥ 100 mSv (mean 184 mSv, maximum 1165 mSv) and their ages were mostly 50–64 years (34.1%), followed by 65–74 years (29.8%), ≥ 75 years (19.5%), 20–49 years (16.3%), and ≤ 19 years (0.29%). Body habitus in decreasing occurrence was obese (38.6%), overweight (31.9%), healthy weight (27.5%), and underweight (2.1%). Classification by dose indicated 172 patients (≥ 500 mSv) and 3 (≥ 1000 mSv). In comparison, 5.3% of 189,030 CT patients, 1.6% of 18,963 FGI patients, and 0.19% of 41,401 nuclear-medicine patients received CED ≥ 100 mSv from a single modality. Conclusions: The study of total dose from CT, FGI, and nuclear medicine of patients with CED ≥ 100 mSv indicates major (89%) contribution of CT to CED with 70% of cohort being obese and overweight, and 64% of cohort aged 50–74 years. Clinical relevance statement: Multimodality recurrent exams are common and there is a lack of information on patient cumulative radiation exposure. This study attempts to address this lacuna and has the potential to motivate actions to improve the justification process for enhancing patient safety. Key Points: • In total, 5.7% of patients undergoing multimodality recurrent imaging (CT, fluoroscopically guided intervention, nuclear medicine) incurred a dose of ≥ 100 mSv. • Mean dose was 184 mSv, with 15 to 18 times contribution from CT than that from fluoroscopically guided intervention or nuclear medicine. • In total, 70% of those who received ≥ 100mSv were either overweight or obese. [ABSTRACT FROM AUTHOR]

Introduction: Tuberculosis remains one of the top ten causes of mortality globally. Children accounted for 12% of all TB cases and 18% of all TB deaths in 2022. Paediatric TB is difficult to diagnose with conventional laboratory tests, and chest radiographs remain crucial. However, in low-and middle-income countries with high TB burden, the capacity for radiological diagnosis of paediatric TB is rarely documented and data on the associated radiation exposure limited. Methods: A multicentre, mixed-methods study is proposed in three countries, Mozambique, South Africa and Spain. At the national level, official registry databases will be utilised to retrospectively compile an inventory of licensed imaging resources (mainly X-ray and Computed Tomography (CT) scan equipment) for the year 2021. At the selected health facility level, three descriptive cross-sectional standardised surveys will be conducted to assess radiology capacity, radiological imaging diagnostic use for paediatric TB diagnosis, and radiation protection optimization: a site survey, a clinician-targeted survey, and a radiology staff-targeted survey, respectively. At the patient level, potential dose optimisation will be assessed for children under 16 years of age who were diagnosed and treated for TB in selected sites in each country. For this component, a retrospective analysis of dosimetry will be performed on TB and radiology data routinely collected at the respective sites. National inventory data will be presented as the number of units per million people by modality, region and country. Descriptive analyses will be conducted on survey data, including the demographic, clinical and programmatic characteristics of children treated for TB who had imaging examinations (chest X-ray (CXR) and/or CT scan). Dose exposure analysis will be performed by children's age, gender and disease spectrum. Discussion: As far as we know, this is the first multicentre and multi-national study to compare radiological capacity, radiation protection optimization and practices between high and low TB burden settings in the context of childhood TB management. The planned comparative analyses will inform policy-makers of existing radiological capacity and deficiencies, allowing better resource prioritisation. It will inform clinicians and radiologists on best practices and means to optimise the use of radiological technology in paediatric TB management. [ABSTRACT FROM AUTHOR]

We established a framework for collecting radiation doses for head, chest and abdomen-pelvis computed tomography (CT) in children scanned at multiple imaging sites across Latin America with an aim towards establishing diagnostic reference levels (DRLs) and achievable doses (ADs) in pediatric CT in Latin America. Our study included 12 Latin American sites (in Argentina, Bolivia, Brazil, Chile, Colombia, Ecuador, Honduras and Panama) contributing data on the four most common pediatric CT examinations (non-contrast head, non-contrast chest, post-contrast chest and post-contrast abdomen-pelvis). Sites contributed data on patients' age, sex and weight, scan factors (tube current and potential), volume CT dose index (CTDIvol) and dose length product (DLP). Data were verified, leading to the exclusion of two sites with missing or incorrect data entries. We estimated overall and site-specific 50th (AD) and 75th (diagnostic reference level [DRL]) percentile CTDIvol and DLP for each CT protocol. Non-normal data were compared using the Kruskal-Wallis test. Sites contributed data from 3,934 children (1,834 females) for different CT exams (head CT 1,568/3,934, 40%; non-contrast chest CT 945/3,934, 24%; post-contrast chest CT 581/3,934, 15%; abdomen-pelvis CT 840/3,934, 21%). There were significant statistical differences in 50th and 75th percentile CTDIvol and DLP values across the participating sites (P<0.001). The 50th and 75th percentile doses for most CT protocols were substantially higher than the corresponding doses reported from the United States of America. Our study demonstrates substantial disparities and variations in pediatric CT examinations performed in multiple sites in Latin America. We will use the collected data to improve scan protocols and perform a follow-up CT study to establish DRLs and ADs based on clinical indications. [ABSTRACT FROM AUTHOR]

Objective: To report the results of a dose survey conducted across 31 provinces in mainland China from 2017 to 2018 and to analyse the dose level to determine the national diagnostic reference levels (DRLs) for paediatric CT procedures. Methods: At least ten patients for each age group (0– < 1, 1– < 5, 5– < 10, 10– < 15 years) and each procedure (head, chest and abdomen) for each CT scanner were selected from four to eight hospitals in each province. The dose information (CTDIvol and DLP) was collected from the HIS or RIS-PACS systems. The median values in each CT scanner were considered the representative dose values for the paediatric patients in CT scanning. The national DRLs were estimated based on the 75th percentile distribution of the median values. Results: A total of 24,395 patients and 319 CT scanners were investigated across 262 hospitals. For paediatric CT scanning in 4 different age groups, the median (P50) and the 75th percentile (P75) of CTDIvol and DLP for each scanning procedure were calculated and reported. National DRLs were then proposed for each procedure and age group. Conclusion: The dose level of CT scanning for children in mainland China was reported for the first time. The DRLs for paediatric CT in the present study are similar to those in some Asian countries but higher than those in European countries. Clinical relevance statement: The paediatric CT is an extensively used tool in diagnosing paediatric disease; however, children are more sensitive to radiation. Establishing the diagnostic reference level of paediatric CT examination is necessary to reduce the dose of CT in children and promote the optimisation of medical exposure. Key Points: • The DRLs for 3 paediatric CT procedures (head, chest and abdomen) and 4 age groups (0– < 1, 1– < 5, 5– < 10, 10– < 15 years) were proposed in mainland China first time. • The examination parameter and dose for children need to be further optimised in China, especially to lower the tube voltage in paediatric CT. [ABSTRACT FROM AUTHOR]

Introduction: Cranial CT scans are associated with radiation exposure to the eye lens, which is a particularly radiosensitive organ. Children are more vulnerable to radiation than adults. Therefore, it is essential to use the available dose reduction techniques to minimize radiation exposure. According to the European Consensus on patient contact shielding by the IRCP from 2021, shielding is not recommended in most body areas anymore. This study aims to evaluate whether bismuth shielding as well as its combination with other dose-saving technologies could still be useful. Methods: Cranial CT scans of a pediatric anthropomorphic phantom were performed on two up-to-date MDCT scanners. Eye lens dose measurements were performed using thermoluminescent dosimeters. Furthermore, the impact of BS and of the additional placement of standoff foam between the patient and BS on image quality was also assessed. Results: Bismuth shielding showed a significant lens dose reduction in both CT scanners (GE: 41.50 ± 4.04%, p < 0.001; Siemens: 29.75 ± 6.55%, p = 0.00). When combined with AEC, the dose was lowered even more (GE: 60.75 ± 3.30%, p < 0.001; Siemens: 41.25 ± 8.02%, p = 0.00). The highest eye dose reduction was achieved using BS + AEC + OBTCM (GE: 71.25 ± 2.98%, p < 0.001; Siemens: 58.75 ± 5.85%, p < 0.001). BS caused increased image noise in the orbital region, which could be mitigated by foam placement. Eye shielding had no effect on the image noise in the cranium. Conclusions: The use of BS in cranial CT can lead to a significant dose reduction, which can be further enhanced by its combination with other modern dose reduction methods. BS causes increase in image noise in the orbital region but not in the cranium. The additional use of standoff foam reduces image noise in the orbital region. [ABSTRACT FROM AUTHOR]

Background: Chest computed tomography (CT) image quality impacts radiologists' diagnoses. Pre-diagnostic image quality assessment is essential but labor-intensive and may have human limitations (fatigue, perceptual biases, and cognitive biases). This study aims to develop and validate a deep learning (DL)-driven multi-view multi-task image quality assessment (M 2 IQA) method for assessing the quality of chest CT images in patients, to determine if they are suitable for assessing the patient's physical condition. Methods: This retrospective study utilizes and analyzes chest CT images from 327 patients. Among them, 1613 images from 286 patients are used for model training and validation, while the remaining 41 patients are reserved as an additional test set for conducting ablation studies, comparative studies, and observer studies. The M 2 IQA method is driven by DL technology and employs a multi-view fusion strategy, which incorporates three scanning planes (coronal, axial, and sagittal). It assesses image quality for multiple tasks, including inspiration evaluation, position evaluation, radiation protection evaluation, and artifact evaluation. Four algorithms (pixel threshold, neural statistics, region measurement, and distance measurement) have been proposed, each tailored for specific evaluation tasks, with the aim of optimizing the evaluation performance of the M 2 IQA method. Results: In the additional test set, the M 2 IQA method achieved 87% precision, 93% sensitivity, 69% specificity, and a 0.90 F1-score. Extensive ablation and comparative studies have demonstrated the effectiveness of the proposed algorithms and the generalization performance of the proposed method across various assessment tasks. Conclusion: This study develops and validates a DL-driven M 2 IQA method, complemented by four proposed algorithms. It holds great promise in automating the assessment of chest CT image quality. The performance of this method, as well as the effectiveness of the four algorithms, is demonstrated on an additional test set. [ABSTRACT FROM AUTHOR]

The AGFAD (Arbeitsgemeinschaft für Forensische Alterdiagnostik, Study Group on Forensic Age Diagnostics) has published several recommendations regarding both technical aspects of computed tomography (CT) of the medial clavicular epiphysis (MCE) and the process of reading and interpreting the CT images for forensic age estimations (FAE). There are, however, no published recommendations regarding CT scan protocols and no dose reference values for CT of the MCE. The objective of this analysis was to assess adherence to AGFAD recommendations among practitioners of FAE and analyse reported dose-relevant CT scan parameters with the objective of helping to establish evidence-based dose reference values for FAE. A systematic literature search was conducted in PubMed and in Google Scholar with specific MeSH terms to identify original research articles on FAE with CT of the MCE from 1997 to 2022. A total of 48 studies were included. Adherence to AGFAD recommendations among practitioners of FAE is high regarding the use of Schmeling main stages (93%), bone window (79%), ≤ 1 mm CT slices (67%), axial/coronal CT images (65%), and Kellinghaus sub-stages (59%). The reporting of CT technique and CT dose-relevant scan parameters is heterogeneous and often incomplete in the current literature. Considering the success achieved by the AGFAD in creating standards of practice of FAE in living subjects, there is potential for the AGFAD to establish standards for radiation protection in FAE as well. [ABSTRACT FROM AUTHOR]

Purpose: To assess accuracy, the frequency of hemorrhagic complications and computed tomography (CT) radiation dose parameters in pediatric patients undergoing landmark-guided external ventricular drain (EVD) placement in an emergency setting. Methods: Retrospective analysis comprised 36 EVD placements with subsequent CT control scans in 29 patients (aged 0 to 17 years) in our university hospital from 2008 to 2022. The position of the EVD as well as the presence and extension of bleeding were classified according to previously established grading schemes. Dose length product (DLP), volume-weighted CT dose index (CTDIvol) and scan length were extracted from the radiation dose reports and compared to the diagnostic reference values (DRLs) issued by the German Federal Office for Radiation Protection. Results: After the initial EVD placement, optimal positioning of the catheter tip into the ipsilateral frontal horn or third ventricle (Grade I), or a functional positioning in the contralateral lateral ventricle or the non-eloquent cortex (Grade II), was achieved in 28 and 8 cases, respectively. In 32 of 36 procedures, no evidence of hemorrhage was present in the control CT scan. Grade 1 (<1 mL) and Grade 2 (≥1 to 15 mL) bleedings were detected after 3 and 1 placement(s), respectively. For control scans after EVD placements, CTDIvol (median [25%; 75% quartile]) was 39.92 [30.80; 45.55] mGy, DLP yielded 475.50 [375.00; 624.75] mGy*cm and the scan length result was 136 [120; 166] mm. Exceedances of the DRL values were observed in 14.5% for CTDIvol, 12.7% for DLP and 65.6% for the scan length. None of these values was in the range requiring a report to the national authorities. Conclusion: Landmark-based emergency EVD placement in pediatric patients yielded an optimal position in most cases already after the initial insertion. Complications in terms of secondary hemorrhages are rare. CT dose levels associated with the intervention are below the reportable threshold of the national DRLs in Germany. [ABSTRACT FROM AUTHOR]

The increasing utilisation of computed tomography (CT) in the medical field has raised a greater concern regarding the radiation-induced health effects as CT imposes high radiation risks on the exposed individual. Adherence to radiation protection measures in CT as endorsed by regulatory bodies; justification, optimisation and dose limit, is essential to minimise radiation risks. Islam values every human being and Maqasid al-Shari'ah helps to protect human beings through its sacred principles which aim to fulfil human beings' benefits (maslahah) and prevent mischief (mafsadah). Alignment of the concept of radiation protection in CT within the framework of al-Dharuriyat; protection of faith or religion (din), protection of life (nafs), protection of lineage (nasl), protection of intellect ('aql) and protection of property (mal) is essential. This strengthens the concept and practices of radiation protection in CT among radiology personnel, particularly Muslim radiographers. The alignment provides supplementary knowledge towards the integration of knowledge fields between Islamic worldview and radiation protection in medical imaging, particularly in CT. This paper is hoped to set a benchmark for future studies on the integration of knowledge between the Islamic worldview and radiation protection in medical imaging in terms of other classifications of Maqasid al-Shari'ah; al-Hajiyat and al-Tahsiniyat. [ABSTRACT FROM AUTHOR]

The authors review the results of 249 patients treated with boron neutron capture therapy (BNCT) at the Helsinki University Hospital, Helsinki, Finland, from May 1999 to January 2012 with neutrons obtained from a nuclear reactor source (FiR 1) and using l-boronophenylalanine-fructose (l-BPA-F) as the boron delivery agent. They also describe a new hospital BNCT facility that hosts a proton accelerator-based neutron source for BNCT. Most of the patients treated with nuclear reactor-derived neutrons had either inoperable, locally recurrent head and neck cancer or malignant glioma. In general, l-BPA-F-mediated BNCT was relatively well tolerated with adverse events usually similar to those of conventional radiotherapy. Twenty-eight (96.6%) out of the evaluable 29 patients with head and neck cancer and treated within a clinical trial either responded to BNCT or had tumor growth stabilization for at least 5 months, suggesting efficacy of BNCT in the treatment of this patient population. The new accelerator-based BNCT facility houses a nuBeam neutron source that consists of an electrostatic Cockcroft–Walton-type proton accelerator and a lithium target that converts the proton beam to neutrons. The proton beam energy is 2.6 MeV operating with a current of 30 mA. Treatment planning is based on Monte Carlo simulation and the RayStation treatment planning system. Patient positioning is performed with a 6-axis robotic image-guided system, and in-room imaging is done with a rail-mounted computed tomography scanner. Under normal circumstances, the personnel can enter the treatment room almost immediately after shutting down the proton beam, which improves the unit capacity. ClinicalTrials.gov ID: NCT00114790. [ABSTRACT FROM AUTHOR]

Paediatric computed tomography (CT) imaging has always been associated with challenges. Although the technical background of CT imaging is complex, it is worth considering the baseline aspects of radiation exposure to prevent unwanted excess radiation in paediatric patients. In this review, we discuss the most relevant factors influencing radiation exposure, and provide a simplified and practical approach to optimise paediatric CT. [ABSTRACT FROM AUTHOR]

Early implant migration is an indicator of the long-term survival/failure of implants. CT-based radio-stereometric analysis (CT-RSA) is a precise method for measuring and visualizing implant migration in vivo using image processing of CT scans. This makes the method widely applicable to orthopedic researcher. Since its development in the early 2000s, CT-RSA has benefited from breakthroughs in CT and computing technology. These advancements have allowed for the acquisition of images with higher resolution at a much lower radiation dose. As a result, the measurement precision of CT-RSA is now comparable to that of the current gold standard technology while still compatible with most ethical considerations regarding radiation exposure. In this review we present bests practices for the successful execution of CT-RSA research projects. These practices are based on experience from projects on the hip, knee, shoulder, lower back, cervical spine, foot, pelvis, and wrist. [ABSTRACT FROM AUTHOR]

Objectives: Published literature on justification of computed tomography (CT) examinations in Europe is sparse but demonstrates consistent sub-optimal application. As part of the EU initiated CT justification project, this work set out to capture CT justification practices across Europe. Methods: An electronic questionnaire consisting of mostly closed multiple-choice questions was distributed to national competent authorities and to presidents of European radiology societies in EU member states as well as Iceland, Norway, Switzerland, and the UK (n = 31). Results: Fifty-one results were received from 30 European countries. Just 47% (n = 24) stated that advance justification of individual CT examinations is performed by a medical practitioner. Radiologists alone mostly (n = 27, 53%) perform daily justification of CT referrals although this is a shared responsibility in many countries. Imaging referral guidelines are widely available although just 13% (n = 6) consider them in daily use. Four countries (Cyprus, Ireland, Sweden, UK) reported having them embedded within clinical decision support systems. Justification of new practices with CT is mostly regulated (77%) although three countries (Belgium, Iceland and Portugal) reported not having any national system in place for generic justification. Health screening with CT was reported by seven countries as part of approved screening programmes and by eight countries outside. When performed, CT justification audits were reported to improve CT justification rates. Conclusions: CT justification practices vary across Europe with less than 50% using advance justification and a minority having clinical decision support systems in place. CT for health screening purposes is not currently widely used in Europe. Key points: CT justification practices vary across Europe. Less than half of respondents reported advance justification of CT examinations. Imaging referral guidelines are widely available but not in daily use. CT for health screening is not widely used in Europe at present. [ABSTRACT FROM AUTHOR]

Background: Computed tomography (CT) contributes to 60% of the collective dose in medical imaging. Literature has demonstrated that patient dose varies across regions and countries. Establishing diagnostic reference levels (DRLs) contributes to the optimization of clinical practices and radiation protection. Purpose: To survey the dose indices (CTDIvol and dose-length product) for frequently performed CT examinations from the chosen hospitals in Norway and Canada and to determine local DRLs (LDRLs) based on the collected data. Material and Methods: The survey included eight scanners from two Norwegian hospitals and four scanners from four Canadian hospitals. Dosimetry data were collected for the following routine CT examinations: head, contrast-enhanced thorax, and abdomen and pelvis. Overall 480 adult average-sized patients from Norway and 360 from Canada were included in the survey. The LDRLs were determined as the 75th percentile of distributions of median values of dose indicators from different CT scanners. The differences in dose between scanners were determined using single-factor ANOVA. Results: The LDRLs determined in Norway were higher overall than in Canada. The obtained values were compared to the national DRLs. The dose from several scanners in Norway exceeded national Norwegian DRLs, while Canadian LDRLs were below the Canadian reference levels. The differences between the means of the dose distributions from each scanner were statistically significant (p < 0.05) for all examinations with exception of identical scanners located in the same hospital and using the same protocols. Conclusion: Observed dose variations even in the same hospital, or from the same scanner model confirmed the need for CT protocol optimization. [ABSTRACT FROM AUTHOR]

This work focuses on the determination of the radiation doses for a total sample of 916 children, categorised into four age groups (<1, 1â€"5, <5â€"10, <10â€"15 years) undergoing the most frequent paediatric CT scans performed in different scan facilities in Tunisia in order to establish the national diagnostic reference levels (DRLs). Dose evaluation concerned the dosimetric indicators: volume computed tomography dose index (CTDIvol) and doseâ€"length product (DLP). The different paediatric CT protocols and practices were also evaluated. The results show a large variation in doses between different radiology departments. For head scans, the respective DRLs for children aged <1, 1â€"5, 5â€"10 and 10â€"15 years were 26, 38, 51 and 51 mGy, respectively, for CTDIvol and 384, 664, 873 and 978 mGy cm, respectively, for DLP. For the chest, the equivalent respective DRLs were 8, 10, 12 and 15 mGy for CTDIvol and 118, 330, 442 and 526 mGy cm for DLP. For the abdomen, the respective DRLs were 9, 13, 19 and 18 mGy for CTDIvol and 353, 485, 592 and 1073 mGy cm for DLP. This study shows that the optimisation of paediatric CT procedures should be a priority, especially within regional hospitals. The implementation of corrective actions will take place after the initial DRLs. These actions, including recommendations and guidelines to good practice, should be a joint effort of all stakeholders, including health authorities, the radiation protection regulator, professional societies and universities. [ABSTRACT FROM AUTHOR]

Introduction: The present study aimed to assess the reduction of breast surface dose, breast radiationinduced cancer incidence, and mortality risks when the lead apron shielding was positioned on the chest regions during head computed tomography (CT). Material and Methods: In this study, routine head CT scans were performed on 28 female patients with a mean body mass index (BMI) of 25.2 ± 2.8 kg/m². The common lead aprons (0.5 mm thicknesses) were folded and positioned in the chest regions. The breast surface doses were measured using six thermoluminescent dosimeters (TLD-100), three TLDs were located above the apron and three ones positioned under the apron. Breast radiation-induced cancer incidence and mortality risks were estimated using the Biological Effects of Ionizing Radiation (BEIR-VII) model. Finally, the measured doses and cancer/mortality risks were compared using Paired sample T-Test in SPSS software. Results: The breast surface doses under and over the apron were obtained at 0.18±0.06 and 0.49±0.13 mGy, respectively, (P-value<0.05). Although all cancer/mortality risks for both groups (over and under the apron) were very low, using the lead apron could decrease (significantly) breast cancer incidence risk ([1.24±0.32]×10-3 % over the apron vs. [0.46±0.15] ×10-3 % under the apron) and mortality risk ([0.30±0.08]×10-3 % over the apron vs. [0.11±0.04] ×10-3 % under the apron) about 63% in all patients. Conclusion: The use of common lead aprons in the chest regions for patients undergoing head CT scans could significantly reduce the breast surface doses and radiation-induced cancer/mortality risks. [ABSTRACT FROM AUTHOR]

For more than two years, coronavirus disease 19 (COVID-19) has represented a threat to global health and lifestyles. Computed tomography (CT) imaging provides useful information in patients with COVID-19 pneumonia. However, this diagnostic modality is based on exposure to ionizing radiation, which is associated with an increased risk of radiation-induced cancer. In this study, we evaluated the common dose descriptors, CTDIvol and DLP, for 1180 adult patients. This data was used to estimate the effective dose, and risk of exposure-induced death (REID). Awareness of the extensive use of CT as a diagnostic tool in the management of COVID-19 during the pandemic is vital for the evaluation of radiation exposure parameters, dose reduction methods development and radiation protection. [ABSTRACT FROM AUTHOR]

Simple Summary: Adjuvant radiotherapy could damage the heart in left-sided breast cancer patients. The deep-inspiration-breath-hold technique may limit the heart exposure to radiation. As non-beneficiaries exist, there is some need to do an upfront cost-effective selection. Some easy-to-use anatomical predictors may help insiders in the treatment decision. The awareness of such findings may improve the efficiency of practitioners' workflows. Radiotherapy represents an essential part of the therapeutic algorithm for breast cancer patients after conservative surgery. The treatment of left-sided tumors has been associated with a non-negligible risk of developing late-onset cardiovascular disease. The cardiac risk perception has especially increased over the last years due to the prolongation of patients' survival owing to the advent of new drugs and an ever earlier cancer detection through screening programs. Improvements in radiation delivery techniques could reduce the treatment-related heart toxicity. The deep-inspiration-breath-hold (DIBH) irradiation is one of the most advanced treatment approaches, which requires specific technical equipment and uses inspiration to displace the heart from the tangential radiation fields. However, not all patients benefit from its use. Moreover, DIBH irradiation needs patient compliance and accurate training. Therefore, such a technique may be unjustifiably cumbersome and time-consuming as well as unnecessarily expensive from a mere healthcare cost point of view. Hence the need to early select only the true beneficiaries while tailoring more effective heart-sparing techniques for the others and streamlining the workflow, especially in high-volume radiation oncology departments. In this literature overview, we collected some possible predictors of cardiac dose sparing in DIBH irradiation for left breast treatment in an effort to provide an easy-to-consult summary of simple instruments to insiders for identifying patients actually benefitting from this technique. We critically reviewed the reliability and weaknesses of each retrieved finding, aiming to inspire new insights and discussions on this much-debated topic. [ABSTRACT FROM AUTHOR]

Background: The present study aimed to evaluate the effectiveness of ultra-low-dose (ULD) chest computed tomography (CT) in comparison with the routine dose (RD) CT images in detecting lung lesions related to COVID-19. Methods: A prospective study was conducted during April-September 2020 at Shahid Faghihi Hospital affiliated with Shiraz University of Medical Sciences, Shiraz, Iran. In total, 273 volunteers with suspected COVID-19 participated in the study and successively underwent RD-CT and ULD-CT chest scans. Two expert radiologists qualitatively evaluated the images. Dose assessment was performed by determining volume CT dose index, dose length product, and size-specific dose estimate. Data analysis was performed using a ranking test and kappa coefficient (κ). P<0.05 was considered statistically significant. Results: Lung lesions could be detected with both RD-CT and ULD-CT images in patients with suspected or confirmed COVID-19 (κ=1.0, P=0.016). The estimated effective dose for the RD-CT protocol was 22-fold higher than in the ULD-CT protocol. In the case of the ULD-CT protocol, sensitivity, specificity, accuracy, and positive predictive value for the detection of consolidation were 60%, 83%, 80%, and 20%, respectively. Comparably, in the case of RD-CT, these percentages for the detection of ground- glass opacity (GGO) were 62%, 66%, 66%, and 18%, respectively. Assuming the result of real-time polymerase chain reaction as true-positive, analysis of the receiver-operating characteristic curve for GGO detected using the ULD-CT protocol showed a maximum area under the curve of 0.78. Conclusion: ULD-CT, with 94% dose reduction, can be an alternative to RD-CT to detect lung lesions for COVID-19 diagnosis and follow-up. An earlier preliminary report of a similar work with a lower sample size was submitted to the arXive as a preprint. The preprint is cited as: https://arxiv.org/abs/2005.03347 [ABSTRACT FROM AUTHOR]

From the Principle of Radiation Protection for workers, radiation shielding is a way to reduce radiation exposure. This study aimed to assess the efficacy of shielding device in reducing effective doses experienced by radiological technologists working in a PET/CT examination room by measuring the equivalent dose with and without shielding device in phantoms using 18F 518 MBq at the National Cyclotron and PET Centre, Chulabhorn Hospital, Thailand. The phantoms were placed at the radiological technologists' working position and nanoDot™ OSL dosimeters were attached at eyes, thyroid, and chest positions for 30 minutes. The experimental results showed that the effective dose measured with and without the radiation shields were 0.249 ± 0.030 mSv and 0.250 ± 0.020 mSv, respectively. Furthermore, data analysis revealed no statistically significant difference (p >0.05) between the two conditions. Hence, it was concluded that the use of radiation shields could not reduce the effective dose. [ABSTRACT FROM AUTHOR]

Introduction: Computed Tomography (CT) is nowadays used widely to differentiate normal brain cranium sutures from abnormal ones in pediatric patients with the aim of early treatment. This study tried to develop a low-dose CT protocol with the acceptable image quality of skull bone in order to evaluate craniosynostosis. Material and Methods: In this study a cranium bone of human cadaver was scanned with standard and reduced dose protocols. Two radiologists verified the quality of skull bone images acquired from the protocol in which there had been 60% dose reduction to scan pediatric patients. The quality of low dose protocol of three dimensional (3D) CT images of skull bone of 57 pediatric subjects suspected of craniosynostosis were compared with standard-dose skull CT images of 44 patients of the same age range. Volume CT dose index (CTDIvol), dose-length product (DLP), and effective dose (ED) were used to evaluate CT dose protocols. The comparison was made by two sample t-test. Results: Mean and standard deviations of CTDIvol, DLP, and ED of standard and reduced doses were 12.4±2.7 mGy, 191.5±54 mGy.cm, 1.94±0.58 mSv and 5.4±0.2 mGy, 85±9 mGy.cm, 0.77±0.17 mSv, respectively, which had statistically significant difference (a=0.05). The quality of skull bone views obtained from low-dose CT protocol were found to be as good as in standard dose. Conclusion: Standard-dose 3D CT protocol of skull bone can be replaced by a 60%-reduced-dose 3D CT protocol with comparable image quality in pediatric patients suspected of craniosynostosis. [ABSTRACT FROM AUTHOR]

Background: In the assessment of diseases causing skeletal lesions such as multiple myeloma (MM), whole-body low-dose computed tomography (WBLDCT) is a sensitive diagnostic imaging modality, which has the potential to replace the conventional radiographic survey. Purpose: To optimize radiation protection and examine radiation exposure, and effective and organ doses of WBLDCT using different modern dual-source CT (DSCT) devices, and to establish local diagnostic reference levels (DRL). Material and Methods: In this retrospective study, 281 WBLDCT scans of 232 patients performed between January 2017 and April 2020 either on a second- (A) or third-generation (B) DSCT device could be included. Radiation exposure indices and organ and effective doses were calculated using a commercially available automated dose-tracking software based on Monte-Carlo simulation techniques. Results: The radiation exposure indices and effective doses were distributed as follows (median, interquartile range): (A) second-generation DSCT: volume-weighted CT dose index (CTDIvol) 1.78 mGy (1.47–2.17 mGy); dose length product (DLP) 282.8 mGy·cm (224.6–319.4 mGy·cm), effective dose (ED) 1.87 mSv (1.61–2.17 mSv) and (B) third-generation DSCT: CTDIvol 0.56 mGy (0.47–0.67 mGy), DLP 92.0 mGy·cm (73.7–107.6 mGy·cm), ED 0.61 mSv (0.52–0.69 mSv). Radiation exposure indices and effective and organ doses were significantly lower with third-generation DSCT (P < 0.001). Local DRLs could be set for CTDIvol at 0.75 mGy and DLP at 120 mGy·cm. Conclusion: Third-generation DSCT requires significantly lower radiation dose for WBLDCT than second-generation DSCT and has an effective dose below reported doses for radiographic skeletal surveys. To ensure radiation protection, DRLs regarding WBLDCT are required, where our locally determined values may help as benchmarks. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the impact of a paediatric radiological protection campaign, implemented in the emergency units of a healthcare provider network in Brazil. This campaign aimed to promote awareness among emergency department physicians, regarding justification of paediatric X-ray referrals for paranasal sinus, chest and CT exams, as a strategy to reduce exposure to ionising radiation. Method: Frequency analysis of common paediatric imaging referrals from 19 emergency departments was performed for a 3-year period (2015–2018) to coincide with before, during and after the implementation of the radiation protection campaign. The campaign was multifaceted and involved dissemination of educational materials and imaging referral guidelines along with quarterly meetings with participating centres' leaderships. Additionally, patient dose cards were distributed to patients/carers. The Chi-Square test was used to examine the association between the type of examination and the patient's age group. Exact-Fisher test was performed to check for an association between participant engagement and the existence of the radiation protection committee. Results: Referrals reduced by 25% following the campaign with no reports of misdiagnosis. Many referrals in the youngest age groups. In 15 units, a radiological protection committee was created to raise awareness and to create a multi professional team to communicate the risks and benefits of radiological procedure in children. Conclusion: The campaign resulted in a substantial reduction in radiological referrals while promoting a radiation protection culture. Simple education initiatives can contribute to savings in both finances and radiation doses, particularly important in radiosensitive cohorts. [ABSTRACT FROM AUTHOR]

Diagnostic reference levels (DRLs) are an optimisation tool for medical imaging procedures using ionising radiation. They give an indication of the expected radiation dose received by an average-sized patient undergoing a given imaging procedure. Comparison of typical (median) exposure levels for common imaging procedures with DRLs helps imaging facilities identify procedures that may be amenable to further optimisation. Undertaking comparisons with published DRLs is a requirement for medical imaging facilities under the Code for Radiation Protection in Medical Exposure and for their access to Medicare rebates under the Diagnostic Imaging Accreditation Scheme (DIAS). The Australian Radiation Protection and Nuclear Safety Agency has created the National Diagnostic Reference Level Service to facilitate the collection of data for the establishment of national DRLs in Australia and to assist imaging facilities in comparing their typical doses with the national DRLs. National DRLs have been established in computed tomography, nuclear medicine, and for image-guided and interventional procedures. DRLs must be subject to ongoing review and revision by the national authority to ensure they reflect current practice. This ongoing cycle of assessment and review helps to ensure that the ratio of benefit to risk for patients is maximised. [ABSTRACT FROM AUTHOR]

Objectives: To evaluate the effects of anatomical phantom structure on task-based image quality assessment compared with a uniform phantom background. Methods: Two neck phantom types of identical shape were investigated: a uniform type containing 10-mm lesions with 4, 9, 18, 30, and 38 HU contrast to the surrounding area and an anatomically realistic type containing lesions of the same size and location with 10, 18, 30, and 38 HU contrast. Phantom images were acquired at two dose levels (CTDIvol of 1.4 and 5.6 mGy) and reconstructed using filtered back projection (FBP) and adaptive iterative dose reduction 3D (AIDR 3D). Detection accuracy was evaluated by seven radiologists in a 4-alternative forced choice experiment. Results: Anatomical phantom structure impaired lesion detection at all lesion contrasts (p < 0.01). Detectability in the anatomical phantom at 30 HU contrast was similar to 9 HU contrast in uniform images (91.1% vs. 89.5%). Detection accuracy decreased from 83.6% at 5.6 mGy to 55.4% at 1.4 mGy in uniform FBP images (p < 0.001), whereas AIDR 3D preserved detectability at 1.4 mGy (80.7% vs. 85% at 5.6 mGy, p = 0.375) and was superior to FBP (p < 0.001). In the assessment of anatomical images, superiority of AIDR 3D was not confirmed and dose reduction moderately affected detectability (74.6% vs. 68.2%, p = 0.027 for FBP and 81.1% vs. 73%, p = 0.018 for AIDR 3D). Conclusions: A lesion contrast increase from 9 to 30 HU is necessary for similar detectability in anatomical and uniform neck phantom images. Anatomical phantom structure influences task-based assessment of iterative reconstruction and dose effects. Key Points: • A lesion contrast increase from 9 to 30 HU is necessary for similar low-contrast detectability in anatomical and uniform neck phantom images. • Phantom background structure influences task-based assessment of iterative reconstruction and dose effects. • Transferability of CT assessment to clinical imaging can be expected to improve as the realism of the test environment increases. [ABSTRACT FROM AUTHOR]

During computed tomography (CT) examinations, radio-sensitive organs located outside the field of view (FOV) are usually exposed to radiation caused by both direct and scattered X-rays. Traditionally, the use of radiation protection products has been an option for reducing exposure doses. The catalog value of the dose reduction factor (DRF) for a commercial X-ray shield is generally determined by the manufacturer using a plain X-ray irradiation system to measure the difference in dose with and without the shield. In contrast, actual shielding ability measurements during clinical CT examinations are usually evaluated using a similar equation, but it is not guaranteed that the incident directions of X-rays will be the same between the measurement data with and without a shield. The purposes of this study are to introduce a novel method for evaluating DRF by accounting for the influence of the X-ray incident direction in helical scanning and to obtain knowledge about the correctness of previously reported DRF values. Experiments pertaining to chest CT examinations were performed using a human body phantom and small-type dosimeters which consist of an optically stimulated luminescence element using Al 2 O 3 :C. A total of 100 examinations were iteratively performed, both with and without a shield. The corresponding DRF was then calculated. The novelty of the proposed analysis procedure lies in a paired analysis method, where the DRF is calculated by reorganizing numerous acquired data sets with and without the shield to pair similar incident angles of X-rays. As a result, the DRF values were estimated to be 48.5 ± 4.3%, 48.7 ± 2.7%, and 48.9 ± 1.5% based on the data results within the 10–40 data sets, 40–70 data sets, and 70–100 data sets, respectively. When the DRF values were obtained by the conventional method without applying our sorting procedure, the results were 48.4 ± 8.1%, even when the 70–100 data sets were used. This result indicates that the proposed method can analyze DRF with higher accuracy. In the example of thyroid X-ray shield, while there was no significant difference in the most probable values of DRF between the conventional and proposed methods coincidentally, we believe it is important to evaluate DRF based on a scientifically correct approach because the mathematical formulas for calculating these two values differ. In conclusion, when calculating the DRF of shielding materials during CT examination, it is imperative that data analysis considers the significant impact of differences in incident X-ray directions on the measured exposure dose data. • ・The differences in X-ray directions should be considered during the CT dosimetry. • ・We proposed a novel method to evaluate the protective ability of an X-ray shield. • ・Our methodology includes an algorithm that sorts the measurement data. • ・In principle, our method can be applied to collar-type thyroid shields. • ・The dose reduction factors reported in the past studies are not necessarily accurate. [ABSTRACT FROM AUTHOR]

The value of dental radiographs to oral health care decision making must be balanced with radiation safety to minimize patient exposure and occupational risk of oral health care providers. This review summarizes recommendations and regulatory guidance regarding dental radiography and cone-beam computed tomography. An expert panel presents recommendations on radiation safety, appropriate imaging practices, and reducing radiation exposure. A systematic search run in Ovid MEDLINE, Embase, and Cochrane Database of Systematic Reviews identified relevant topical systematic reviews, organizational guidelines, and regulatory reviews published in the peer-reviewed literature since 2010. A supplemental search of the gray literature (eg, technical reports, standards, and regulations) identified topical nonindexed publications. Inclusion criteria required relevance to primary oral health care (ie, general or pediatric dentistry). A total of 95 articles, guidance documents, and regulations met the inclusion criteria. Resources were characterized as applicable to all modalities, operator and occupational protection, dose reduction and optimization, and quality assurance and control. Understanding factors affecting imaging safety and applying fundamental principles of radiation protection consistent with federal, state, and local requirements are essential for limiting patient ionizing radiation exposure, in conjunction with implementing optimal imaging procedures to support prudent use of dental radiographs and cone-beam computed tomographic imaging. The regulatory guidance and best practice recommendations summarized in this article should be followed by dentists and other oral health care providers. [ABSTRACT FROM AUTHOR]

• A large variation of dose values per procedure and department were found. • DRLs were defined for PTBD, BAE, TACE, IEAE, TIPS e ETFPA, in terms of P KA in Gy.cm2, K a,r in mGy and Fluoro time (FT) in minutes. • The results revealed a relevant potential for optimisation and harmonisation of dose values. • Standardisation of data collection methods to set national DRLs in order to facilitate comparisons. To establish Portuguese Diagnostic Reference Levels (DRLs), for six body fluoroscopy guided interventional procedures (FGIP). A retrospective study was conducted in five interventional departments most representative of Interventional Radiology (IR) practice. Dose values, in terms of air kerma area product (P KA in Gy.cm2), air kerma at the patient entrance reference point (K a,r in mGy), and exposure parameters (fluoroscopy time (FT) and number of cine runs) were collected. Examinations were selected per procedure (at least 20), according to the antero-posterior and lateral diameter mean value (±5 cm), measured on previous Computed Tomography (CT) examinations. Data of 489 body FGIP show a large variation on dose values per procedure and per department. National DRLs in terms of P KA were 20.2 Gy.cm2 for Percutaneous transhepatic biliary drainage (PTBD), 98.2 Gy.cm2 for Bronchial artery embolisation (BAE), 247.7 Gy.cm2 for Transarterial chemoembolisation (TACE), 331.6 Gy.cm2 for Inferior epigastric arteries embolisation (IEAE), 312.0 Gy.cm2 for Transjugular intrahepatic portosystemic shunt (TIPS) and 19.3 Gy.cm2 for Endovascular treatment of femoral popliteal arteries (ETFPA). This is the first study reporting Interventional Radiology DRLs in Portugal and we propose preliminary national estimates for the six more common body FGIP. The results of this study will be presented and discussed with all Portuguese IR departments, to promote procedures optimisation. [ABSTRACT FROM AUTHOR]

Computed Tomography (CT) continues to contribute a significant portion of the total collective dose delivered to the public from medical procedures involving ionizing radiation. Children are considered to be at higher risk of developing radiation induced cancer due to the young age of exposure and increased tissue radio sensitivity. Organ dose estimation is essential for pediatric patient cancer risk assessment. The aim of this study was to evaluate the excess risk of radiation induced cancer following exposure to low-dose ionizing radiation from pediatric CT scans. We collected information from Radiation Dose Structured Report (RDSR) in 2 radiology department for 3 protocols and three (3) different age group in pediatric CT scan. We estimated the excess of cancer risk by using the Radiation Risk Assessment Tool RadRAT). For that, we calculate first the organ doses with National Cancer Institute for CT (NCICT). Effective dose and Size Specific Dose Estimate were also estimated, CTDI and DLP recorded from the RDSR were compared by the ones given by the software. The doses received by 30 organs including both inside and outside the scanning range were calculated and compared for the different age groups and protocols. The excess risk observed here range between 0.6 and 10.1‰ for respectively the thorax and Abdomen protocol in boy's cohort. This can be due to the significant dose variability observed among radiological protocols defined for the same CT scan and patient of the same age. For a head examination, a ratio of 2–4, depending on the age of the child, is estimated between the maximum and minimum doses delivered to the brain. For the other types of examination, this ratio is even greater: around 9 for chest examinations, 16 for abdominopelvic explorations. Careful justification of pediatric CT scans and dose optimization should be available in hospitals to minimize risks. • CT scan is the most widely used imaging modality but also the most irradiating compared to conventional radiography. • Optimization methods can decrease doses received by patients during diagnostic. • Organ doses allows to predict the future cancer risk. • Pediatric patients are more radiosensitive to radiations compared with adults. [ABSTRACT FROM AUTHOR]

Purpose: The exposure of both patient and operator to radiation is one of the limitations of computed tomography (CT)-guided interventions, and it should be kept as low as reasonably possible. The purpose of the study was to evaluate the efficacy of a lead screen in reducing the radiation dose to an operator in the course of CT-guided interventions. Material and methods: This prospective study analysed data collected from 72 consecutive CT-guided procedures, all of which were performed with an X-ray protective lead screen placed between the scanner and the operator. Five dosimeters were placed in the CT scanning room, and accumulated radiation doses were measured for each dosimeter. Results: The dosimeter placed on the gantry side of the lead screen revealed highest levels of radiation (11.33 ± 1.93 mSv), which were significantly higher than those at all other dosimeters. The radiation dose behind the lead screen was almost the same when measured by dosimeters on the CT scanner gantry side and 3 metres away from it. The presence of the screen caused no discomfort for operators. Conclusions: A lead screen reduces an operator’s radiation exposure significantly, while not posing any obstacles or causing any discomfort while CT-guided procedures are carried out. [ABSTRACT FROM AUTHOR]

Introduction: Describe the profile of patients referred for computed tomography (CT) likely to be scanned with scintigraphy imaging in Togo. Methods: Prospective study carried out from May 15 to August 15 2020 including patients referred for non-traumatic CT scans (excluding strokes) in all the radiology centres in Togo with operational CT scans. The good practice guide of the French Societies of Radiology (SFR) and Nuclear Medicine (SFMN) was used as a reference for case selection. Results: A total of 328 patients, representing 14.6% of those referred for non-traumatic CT scans (excluding strokes) were concerned. The sex ratio was 0.74 and the average age 50.58 ± 19.02 years. The patients had a health insurance in 50% of cases and were civil servants in 62.5% of cases. They mainly came from the cardiology (6.7%) and oncology departments (6.1%). Most common explorations were chest-abdomen-pelvis CT scans (36.3%) and thorax angiography CT (22.9%). Pulmonary embolism (24.1%), breast and prostate cancer extension assessment (18.3%) were the most frequent indications. Scintigraphy was indicated mainly (85.37%) as a second line of exploration. The most concerned fields of nuclear medicine were nuclear oncology (26.2%), cardio-pneumology (25%) and nuclear neurology (20.1%). Scintigraphy imaging was of a better or the same grade of recommendation as CT scan in 53.7% of cases, and of a lower or the same dose class as CT scan in 90.2% of cases. Conclusion: A significant number of patients referred for CT scans in Togo were likely to be explored by scintigraphy imaging, hence the need to create a nuclear medicine department there. [ABSTRACT FROM AUTHOR]

Purpose: There is no data that show if it is possible to determine if a curve is structural or non-structural or to assess flexibility of an adolescent idiopathic scoliosis (AIS) by recumbent images like a CT scan (CTS) instead of bending radiographs (BR). We investigated if the results of BR may be compared to those of CTS. Methods: We retrospectively analyzed prospectively collected data of patients with AIS in whom a selective spinal fusion was performed and in whom a CTS, BR, and full spine x-rays were made preoperatively. We measured the Cobb angles of the main and the minor curve in full spine x-ray, BR, and CTS. Results: After applying inclusion and exclusion criteria, 39 patients were included. We found a strong correlation (r = 0.806, p < 0.01) between the Cobb angle of the main curve in BR and the Cobb angle of the main curve in the CTS and between the Cobb angle of the minor curve in BR and the Cobb angle of the minor curve in the CTS (r = 0.601, p < 0.01). All patients with a minor curve of less than 25 degrees in the BR had a Cobb angle of less than 35 degrees in the CTS. Conclusion: Spinal curves showed a significant correlation between bending radiographs and recumbent images (CTS). In our group of patients, a Cobb angle of the minor curve of less than 35 degrees in the CTS indicated that this minor curve was non-structural. [ABSTRACT FROM AUTHOR]

Millions of patients benefit from medical imaging every single day. However, we have entered an unprecedented era in imaging practices wherein 1 out of 125 patients can be exposed to effective dose >50 mSv from a single CT exam and 3 out of 10,000 patients undergoing CT exams could potentially receive cumulative effective doses > 100 mSv in a single day. Recurrent imaging with CT, fluoroscopically guided interventions, and hybrid imaging modalities such as positron emission tomography/computed tomography (PET/CT) is more prevalent today than ever before. Presently, we do not know the cumulative doses that patients may be receiving across all imaging modalities combined. Furthermore, patients with diseases with longer life expectancies are being exposed to high doses of radiation enabling radiation effects to manifest over a longer time period. The emphasis in the past on improving justification of imaging and optimization of technique and practice has proved useful. While that must continue, the current situation requires imaging device manufacturers to urgently develop imaging technologies that are safer for patients as high doses have been observed in patients where imaging has been justified through clinical decision-support and optimized by keeping doses below the national benchmark doses. There is a need to have a critical look at the fundamental principles of radiation protection as cumulative doses are likely to increase in the coming years. [ABSTRACT FROM AUTHOR]

Objectives: To assess the magnitude and characterization of CT imaging protocols of patients receiving 50 or 100 mSv in a single day. Methods: In this multicentric retrospective study covering up to 279 hospitals from January 2015 to December 2019, the effective dose (E) as estimated by dose management system from dose length product of patients was filtered and grouped into per-day dose bands (≤ 20, > 20–50, > 50–70, > 70–100, > 100–200, > 200 mSv). Information on patient's age and imaging protocol was noted. The data were analyzed to determine the frequency of occurrence in each dose band. Top 20 CT imaging protocols that led to patients with a dose of ≥ 50 mSv in a single acquisition were identified and their relative frequency was estimated. Results: A total of approx. 4.3 million (4,283,738) CT exams were performed in approx. 3.9 million (3,880,524) patient-days indicating 9.41% had more than one CT exam in a single day. There were 31,058 (0.8%) patient-days with ≥ 50 mSv and 1191 (0.03%) with ≥ 100 mSv. Nearly 1/3rd patient-days reaching ≥ 50 mSv were of patients aged 50 years or younger. The top 20 CT imaging protocols that led to ≥ 50 mSv in a single day belonged to the body region (chest or abdomen and pelvis) and nearly one-third were angiographic studies. Conclusions: In the first study of its kind, we report that patients with 50 mSv+ in a single day or a single exam are not rare. The information on imaging protocols leading to such doses and their frequency has been provided to help develop dose management strategies. Key Points: • Our study of 4,283,738 CT exams performed in 3,880,524 patient-days indicates 0.8% with 50 mSv+ and 0.03% with 100 mSv+ in a single day. • A total of 9.41% underwent more than one CT exam in a single day; nearly 1/3rdof those with 50 mSv+ were ≤ 50 years of age. • Identified top 20 CT imaging protocols that led to 50 mSv+ doses in a single exam. All belong to chest or abdomen and pelvis and nearly 1/3rdwere angiographic studies. [ABSTRACT FROM AUTHOR]

Objectives: To estimate the number of patients who receive a cumulative effective dose (CED) of ≥ 100 mSv from computed tomography (CT) in a single day or episode of care.Methods: We examined 28,870 patients who underwent 49,834 CT examinations in a tertiary care centre in Italy in 2.5 years. Radiation exposures were retrieved from the hospital's automatic exposure monitoring system. Two cohorts were identified as those who received a CED of ≥ 100 mSv in a single day and within a month starting from the first examination. Organ doses were estimated for the first cohort.Results: Among the 1765 (6.1%) patients who received CED ≥ 100 mSv in the observation period, 427 received a CED of ≥ 100 mSv within a month (and 70 patients in a single day). This group represented 1.5% of all patients who underwent CT exams and 24% of those who received CED ≥ 100 mSv in the observation period. The clinical indication for referral included cancer in 132 patients (31%) and non-oncological indications in 295 patients (69%). In 68/70 patients with CED > 100 mSv in a single day, at least one organ/tissue received a dose of ≥ 100 mGy.Conclusions: The finding of a sizeable percentage of patients undergoing CT exams and receiving CED ≥ 100 mSv in a single episode of care points toward the need of imaging appropriateness criteria, to revise the routine protocols, to replace older machines, and to provide to the radiologist the patient's prior radiation history to facilitate an appropriate decision-making process.Key Points: • Patients can receive effective doses greater than 100 mSv in a single CT or in multiple CT examinations performed in a single episode of care in 1.5% of patients in a 2.5-year period. • In this study, the clinical indication for CT referral was non-oncological in 69% of patients. • The patient's prior radiation history should be provided to the referring physicians and the radiological medical practitioner to facilitate an appropriate decision-making process. [ABSTRACT FROM AUTHOR]

Objectives: To survey (1) operator's eye lens doses in typical computed tomography (CT)-guided interventions, (2) correlation between dose length product (DLP) and the operator's dose, and (3) different ways for estimating the eye lens dose in clinical settings.Methods: Doses of 16 radiologists in 164 CT-guided interventional procedures were prospectively measured during a 6-month time period upon radioprotective garments and descriptive statistical outcomes were calculated. The correlations between DLP and measured doses were surveyed.Results: On average, the operator's dose at the eye level (DEL, Hp(0.07)) was 22 μSv per procedure and the personal equivalent dose Hp(10) at the collar level was 21 μSv per procedure. The mean DLP of a procedure was 320 mGy cm, where 54% resulted from the fluoroscopy, the mean exposure time being 18 s. Based on the results, the operator's DEL could be estimated from DLP using the equation DEL (μSv) = 0.10 μSv/mGy cm × patient fluoro DLP (mGycm) (p < 0.001), and the dose at the collar level (DCL) using the equation DCL (μSv) = 0.12 μSv/mGy cm × patient fluoro DLP (mGy cm) (p < 0.001). In addition, DEL (μSv) = 0.7 × DCL (μSv).Conclusions: The eye lens doses in CT-guided interventions are generally low even without protective equipment, and it is unlikely that the recommended annual equivalent dose limit of 20 mSv for the lens of the eye will be exceeded by conducting CT-guided interventions solely. Eye lens dose can be roughly estimated based on either DLP of the procedure or dose measured at the operator's collar level.Key Points: • Eye lens doses in CT-guided operations are generally low. • It is unlikely that the ICRP recommendation of the yearly equivalent dose limit of 20 mSv will be exceeded by conducting CT-guided interventions solely. • Magnitude of eye lens dose can be estimated based on either DLP of the procedure or dose measured at the operator's collar level. [ABSTRACT FROM AUTHOR]

Objective: To identify a patient cohort who received ≥ 100 mSv during a single computed tomography (CT)-guided intervention and analyze clinical information. Materials and methods: Using the dose-tracking platform Radimetrics that collects data from all CT scanners in a single hospital, a patient-level search was performed retrospectively by setting a threshold effective dose (E) of 100 mSv for the period from January 2013 to December 2017. Patients who received ≥ 100 mSv in a single day during a single CT-guided intervention were then identified. Procedure types were identified, and medical records were reviewed up to January 2020 to identify patients who developed short- and/or medium-term (up to 8 years) medical consequences. Results: Of 8952 patients with 100 mSv+, there were 33 patients who underwent 37 CT-guided interventions each resulting in ≥ 100 mSv. Procedures included ablations (15), myelograms (8), drainages (7), biopsies (6), and other (1). The dose for individual procedures was 100.2 to 235.5 mSv with mean and median of 125.7 mSv and 111.8 mSv, respectively. Six patients (18 %) were less than 50 years of age. During the study period of 0.2 to 7 years, there were no deterministic or stochastic consequences identified in this study cohort. Conclusions: While infrequent, CT-guided interventions may result in a single procedure dose of ≥ 100 mSv. Awareness of the possibility of such high doses and potential for long-term deleterious effects, especially in younger patients, and consideration of alternative imaging guidance and/or further dose optimization should be strongly considered whenever feasible. Key Points: • Although not so frequent, CT-guided interventions may result in a single procedure dose of ≥ 100 mSv • Procedures with potential for high dose includes ablations, myelograms, drainages, and biopsies [ABSTRACT FROM AUTHOR]

We numerically study the computed tomography dose index (CTDI) quantity based on the Monte Carlo method using GATE software. In this work, it was demonstrated that the CTDI values decreased following an exponential form as a function of phantom diameter. As expected, the absorbed dose is shown to have a good relationship which increases linearly with X-ray tube current (mAs) values. The simulation presented in particularly that the (CTDI) dose increases not-linearly dependence with photon deposited energy (kVp). It seems that the average percent of the absorbed dose in the abdominal phantom was lower than the heat phantom object's absorbed dose, which was equal to 80%. In conclusion, the use of Monte Carlo simulation represents a dosimetry tool for radiation protection in the field of radiology imaging. [ABSTRACT FROM AUTHOR]

The purpose of this study was to evaluate the dose and image to assess a shielding made of barium sulfate for the protection of supersensitive radiation eye lens and superficial breast during CT scanning. Doses were measured by CT scan of the head and chest phantoms with a polymethylmethacrylate (PMMA) phantom consisting of holes (designated in sequence at 0°, 90°, 180°, and 270°). Dose measurement of the eye lens was performed using a 16 cm head phantom and chest breast dose measurement was performed using a 32 cm PMMA body phantom. The dose was measured using a barium shield and the dose reductions in the head and chest phantoms were calculated by comparing the doses of the reference. For image evaluation, HU and noise on the left and right sides were measured by dividing them into the anterior, lateral (90°, 270°), and posterior positions. To evaluate the barium shielding image, the image was evaluated by selecting a surface plot using the ImageJ program. The head phantom dose decreased by 12.4% maximum in the anterior position (0°) and the chest phantom showed a decrease of 31.37% in the anterior (0°) and 33.63% in the lateral (90°) positions. In the comparison of noise of the image, the head phantom showed an increase of 50.43% in the anterior position. There was a significant difference in dose at positions other than the lateral (270°) and posterior (180°) positions (p < 0.05). Scanning the chest phantom in the anterior position increased the noise by up to 90.66% in the noise comparison (270°) and the posterior (180°) position showed significant differences in image (p < 0.05). In the CT scan using a barium-based shielding agent, the dose was reduced by 3.3–12.4% in the head and 3.62–33% in the chest. The barium shielding agent should be used for the examination by reducing the dose and maintaining the image quality by applying it efficiently during CT examination. [ABSTRACT FROM AUTHOR]

Background: According to international guidelines, radiological examinations of the lumbar spine are of limited value and do not improve clinical outcome unless there are clinical red flags present suggesting serious pathology. Nevertheless, the utilization of lumbar spine imaging remains high.Purpose: To follow up the effects of active referral guideline implementation and education on the number and appropriateness of lumbar spine radiographs and computed tomography (CT) examinations in young patients and to evaluate whether the appropriate radiographs have more significant findings.Material and Methods: Referral guidelines for spine examinations and info pocket cards on radiation protection were distributed to referring practitioners. Educational lectures were provided annually. The number of lumbar spine radiographs and CT examinations on patients aged <35 years was analyzed before and three years after the interventions. Appropriateness and findings of 313 radiographs and appropriateness of 117 CT scans of the lumbar spine were assessed.Results: The number of lumbar spine radiographs and CT scans decreased significantly after the interventions and the level remained unchanged during the follow-up (-33% and -72%, respectively, P < 0.001). Appropriateness improved significantly in radiographs from 2005 to 2009 (65% vs. 85%) and in CT scans already from 2005 to 2007 (23% vs. 63%). Radiographs that were in accordance with the guidelines had more significant findings compared to radiographs that were not; in young adults, this was 56% versus 21% (P < 0.001).Conclusion: A combination of interventions can achieve a sustained reduction in the number of lumbar spine examinations and improve appropriateness. Inappropriate lumbar spine radiographs do not seem to contain significant findings that would affect patient care. [ABSTRACT FROM AUTHOR]

Objectives: Detectability experiments performed to assess the diagnostic performance of computed tomography (CT) images should represent the clinical situation realistically. The purpose was to develop anatomically realistic phantoms with low-contrast lesions for detectability experiments.Methods: Low-contrast lesions were digitally inserted into a neck CT image of a patient. The original and the manipulated CT images were used to create five phantoms: four phantoms with lesions of 10, 20, 30, and 40 HU contrast and one phantom without any lesion. Radiopaque 3D printing with potassium-iodide-doped ink (600 mg/mL) was used. The phantoms were scanned with different CT settings. Lesion contrast was analyzed using HU measurement. A 2-alternative forced choice experiment was performed with seven radiologists to study the impact of lesion contrast on detection accuracy and reader confidence (1 = lowest, 5 = highest).Results: The phantoms reproduced patient size, shape, and anatomy. Mean ± SD contrast values of the low-contrast lesions were 9.7 ± 1.2, 18.2 ± 2, 30.2 ± 2.7, and 37.7 ± 3.1 HU for the 10, 20, 30, and 40 HU contrast lesions, respectively. Mean ± SD detection accuracy and confidence values were not significantly different for 10 and 20 HU lesion contrast (82.1 ± 6.3% vs. 83.9 ± 9.4%, p = 0.863 and 1.7 ± 0.4 vs. 1.8 ± 0.5, p = 0.159). They increased to 95 ± 5.7% and 2.6 ± 0.7 for 30 HU lesion contrast and 99.5 ± 0.9% and 3.8 ± 0.7 for 40 HU lesion contrast (p < 0.005).Conclusions: A CT image was manipulated to produce anatomically realistic phantoms for low-contrast detectability experiments. The phantoms and our initial experiments provide a groundwork for the assessment of CT image quality in a clinical context.Key Points: • Phantoms generated from manipulated CT images provide patient anatomy and can be used for detection tasks to evaluate the diagnostic performance of CT images. • Radiologists are unconfident and unreliable in detecting hypodense lesions of 20 HU contrast and less in an anatomical neck background. • Detectability experiments with anatomically realistic phantoms can assess CT image quality in a clinical context. [ABSTRACT FROM AUTHOR]

Objective: The aim of this study was to measure occupational exposure doses of technologists who dispense and inject radiopharmaceuticals in 7 positron emission tomography/computed tomography (PET/CT) departments. This was done with the goal to help improving protective designs in PET departments and/or establishing national protection standards. Method: Common LiF thermoluminescence dosimeters (TLDs) were placed on the chest and necklace of the technologists to monitor whole-body and thyroid doses, respectively. Ring TLDs were also worn on both index fingers to measure individual hand doses. All TLDs were assembled and measured once every 3 months for a total of 12 months. Additionally, we measured and compared the dose of TLDs attached to both the inside and the outside of the technologist’s lead coat. Results: Technologists received relatively high exposures, which accounted for 64% to 94% of the collective dose in their respective departments. Their thyroid doses ranged from 1.2 to 1.7 mSv/a; some technologists’ hand doses exceeded 500 mSv/a. Use of a lead coat reduced the average dose by 8%. Conclusion: Technologists working in PET/CT departments were the main population exposed to radiation. This work underscores the need for enhanced protective measures for these workers to better reduce their exposure, particularly for their hands. [ABSTRACT FROM AUTHOR]

Optimization of injected gallium-68 (68Ga) activity for 68Ga-prostate-specific membrane antigen positron emission tomography/computed tomography (68Ga-PSMA PET/CT) studies is relevant for image quality, radiation protection, and from an economic point of view. However, no clear guidelines are available for 68Ga-PSMA studies. Therefore, a phantom study is performed to determine the highest coefficient of variation (COV) acceptable for reliable image interpretation and quantification. To evaluate image interpretation, the relationship of COV and contrast-to-noise ratio (CNR) was studied. The CNR should remain larger than five, according to the Rose criterion. To evaluate image quantification, the effect of COV on the percentage difference (PD) between quantification results of two studies was analyzed. Comparison was done by calculating the PD of the SUVmax. The maximum allowable PDSUVmax was set at 20%. The highest COV at which both criteria are still met is defined as COVmax. Of the NEMA Image Quality phantom, a 20 min/bed (2 bed positions) scan was acquired in list-mode PET (Philips Gemini TF PET/CT). The spheres to background activity ratio was approximately 9:1. To obtain images with different COV, lower activity was mimicked by reconstructions with acquisition times of 10 min/bed to 5 s/bed. Pairs of images were obtained by reconstruction of two non-overlapping parts of list-mode data. For the 10-mm diameter sphere, a COV of 25% still meets the criteria of CNRSUVmean ≥ 5 and PDSUVmax ≤ 20%. This phantom scan was acquired with an acquisition time of 116 s and a background activity concentration of 0.71 MBq/kg. Translation to a clinical protocol results in a clinical activity regimen of 3.5 MBq/kg min at injection. To verify this activity regimen, 15 patients (6 MBq/kg min) with a total of 22 lesions are included. Additional reconstructions were made to mimic the proposed activity regimen. Based on the CNRSUVmax, no lesions were missed with this proposed activity regimen. For our institution, a clinical activity regimen of 3.5 MBq/kg min at injection is acceptable, which indicates that activity can be reduced by almost 50% compared with the current code of practice. Our proposed method could be used to obtain an objective activity regimen for other PET/CT systems and tracers. [ABSTRACT FROM AUTHOR]

Introduction: In 2018, ARPANSA published updated national DRLs for adult CT, which were first published in 2012, and augmented the national DRL categories. This paper presents the updated national DRLs and describes the process by which they were produced. Methods: Examine patient survey data submitted to the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) National Diagnostic Reference Level Service (NDRLS). Determine the quartiles of the distributions of median survey dose metrics with categorisation by procedure type. Engage a liaison panel representing the radiology professions to review procedure categories and recommend revised national DRLs. The revised NDRL procedure categories are: head (non‐contrast brain (trauma/headache)), cervical spine (Non‐contrast (trauma)), soft‐tissue neck (post‐contrast (oncology)), chest (post‐contrast (oncology)), abdomen–pelvis (post‐contrast (oncology)), kidney–ureter–bladder (non‐contrast (suspected renal colic)), chest–abdomen–pelvis (post‐contrast (oncology)) and lumbar spine (non‐contrast (degenerative pain)). Results: The existing six procedure categories were revised and refined. Updated Australian national diagnostic reference levels for adult CT were recommended and endorsed for eight procedure categories: head (52 mGy/880 mGycm), cervical spine (23 mGy/470 mGycm),soft‐tissue neck (17 mGy/450 mGycm), chest (10 mGy/390 mGycm), abdomen–pelvis (13 mGy/600 mGycm), kidney–ureter–bladder (13 mGy/600 mGycm), chest–abdomen–pelvis (11 mGy/940 mGycm) and lumbar spine (26 mGy/670 mGycm). The updated national DRLs are between 12 and 26% lower than the previous DRLs for dose‐length product and between 13 and 63% lower for volume computed tomography dose index. Conclusions: Australian national DRLs for adult CT have been reviewed and revised. The revised national DRLs are lower, better reflecting current practice among imaging facilities in Australia. The revised Australian national DRLs are similar to those in other developed countries. [ABSTRACT FROM AUTHOR]

Objectives: To report on a dose survey conducted by the French societies of radiology and paediatric imaging (SFR and SFIPP) and the French public service expert in nuclear and radiological risks (IRSN), and to suggest new diagnostic reference levels (DRLs) for paediatric CT.Methods: Dose reports concerning children aged 0-15 years and five CT procedures (brain, petrous bone, mediastinum, lung and abdomen-pelvis) performed in 2015-2016 were collected from 15 imaging departments on a voluntary basis. Volume CT dose index (CTDIvol) and dose-length product (DLP) were recorded for at least 10 patients per procedure, per centre and per age group. New DRLs were calculated as the 3rd quartiles of the distributions of the median values.Results: Results from 3253 CT examinations were obtained. The exposure levels observed were much lower than for the previous surveys (2007-2008 and 2010-2013) and among the lowest values currently published. A good homogeneity between facilities was also observed. New DRLs are proposed for each procedure and age group.Conclusions: This new survey contributes to the continuing optimisation process in French paediatric CT practice. Its results have been recently used to update the national paediatric CT DRLs.Key Points: • New national diagnostic reference levels (DRLs) are proposed for several paediatric CT procedures. • The DRLs proposed for brain, chest and abdomen-pelvis procedures are among the lowest published worldwide. [ABSTRACT FROM AUTHOR]