No abstract

Ob jectives The European Society of Radiology identified 10 common indications for computed tomography (CT) as part of the European Study on Clinical Diagnostic Reference Levels (DRLs, EUCLID), to help standardize radiation doses. The objective of this study is to generate DRLs and median doses for these indications using data from the UCSF CT International Dose Registry. Methods Standardized data on 3.7 million CTs in adults were collected between 2016 and 2019 from 161 institutions across seven countries (United States of America (US), Switzerland, Netherlands, Germany, UK, Israel, Japan). DRLs (75th percentile) and median doses for volumetric CT-dose index (CTDIvol) and dose-length product (DLP) were assessed for each EUCLID category (chronic sinusitis, stroke, cervical spine trauma, coronary calcium scoring, lung cancer, pulmonary embolism, coronary CT angiography, hepatocellular carcinoma (HCC), colic/abdominal pain, appendicitis), and US radiation doses were compared with European. Results The number of CT scans within EUCLID categories ranged from 8,933 (HCC) to over 1.2 million (stroke). There was greater variation in dose between categories than within categories (p < .001), and doses were significantly different between categories within anatomic areas. DRLs and median doses were assessed for all categories. DRLs were higher in the US for 9 of the 10 indications (except chronic sinusitis) than in Europe but with a significantly higher sample size in the US. Conclusions DRLs for CTDIvol and DLP for EUCLID clinical indications from diverse organizations were established and can contribute to dose optimization. These values were usually significantly higher in the US than in Europe. Key Points • Registry data were used to create benchmarks for 10 common indications for CT identified by the European Society of Radiology. • Observed US radiation doses were higher than European for 9 of 10 indications (except chronic sinusitis). • The presented diagnostic reference levels and median doses highlight potentially unnecessary variation in radiation dose.

IMPORTANCE Computed tomography (CT) radiation doses vary across institutions and are often higher than needed.OBJECTIVE To assess the effectiveness of 2 interventions to reduce radiation doses in patients undergoing CT. DESIGN, SETTING, AND PARTICIPANTSThis randomized clinical trial included 864 080 adults older than 18 years who underwent CT of the abdomen, chest, combined abdomen and chest, or head at 100 facilities in 6 countries from

Patent ductus arteriosus stenting for ductal-dependent pulmonary blood flow is a technically challenging neonatal procedure to maintain a stable pulmonary circulation. Pre-procedural computed tomography imaging aids in outlining ductal origin, insertion, size, course and curvature. Computed tomography imaging may add value to procedural outcomes and reduce overall procedural morbidity in neonatal patent ductus arteriosus stenting. We conducted a single centre retrospective chart review of neonates with ductal-dependent pulmonary blood flow who underwent patent ductus arteriosus stenting between January 1, 2014 and June 31, 2020. We compared patients variables between patients who underwent pre-procedural computed tomography imaging to those who did not. A total of 64 patients were referred for patent ductus arteriosus stenting with 33 (52%) obtaining pre-procedural computed tomography imaging. Average age [19 days; range 1–242 days (p = 0.85)] and weight [3.3 kg (range 2.2–6.0 kg; p = 0.19)] was not significantly different between the groups. A diagnosis of pulmonary atresia was made in 42 out of 64 (66%) patients prior to patent ductus arteriosus stenting. The cohort with pre-intervention computed tomography imaging had a significant reduction in the total number of access sites (1.2 versus 1.5; p = 0.03), contrast needed (5.9 versus 8.2 ml/kg; p = 0.008), fluoroscopy (20.7 versus 38.8 minutes; p = 0.02) and procedural time (83.4–128.4 minutes; p = 0.002) for the intervention. There was no significant difference in radiation burden between the groups (p = 0.35). Pre-procedural computed tomography imaging adds value by aiding interventional planning for neonatal patent ductus arteriosus stenting. A statistically significant reduction in the number of access sites, contrast exposure, as well as fluoroscopic and procedural time was noted without significantly increasing the cumulative radiation burden.

No abstract

Purposewe aimed to investigate the effect of various β-value in BSREM algorithm under different lesion sizes, in order to determine an optimal penalty factor for clinical use. MethodsThe NEMA IQ phantom and 15 patients with prostate cancer were injected with 68Ga-PSMA and scanned by GE Discovery IQ PET/CT scanner. Images were reconstructed using OSEM and BSREM with different β-values and then background variability (BV), contrast recovery (CR), signal-to-noise ratio (SNR), and lung residual error (LE) from phantom data, and Signal-to-Background Ratio (SBR), contrast from clinical data were measured. ResultsThe increment of BV using β-value of 100 was 120% and the decrement of BV using β-value 1000 were 40.5% compared to OSEM. As the β decreased from 1000 to 100, the SUV max increased by 59% and 26.4% for sphere with diameter of 10 mm and 37 mm, respectively.Δ SNR (100-1000) % increased by 140.5 and 29.0 in the smallest and the largest sphere, respectively. The Δ LE OSEM-100 and Δ LE OSEM-1000 was − 41.1% and − 36.7% respectively. In the clinical study, the lowest SBR and contrast was related to the OSEM. The SBR and contrast, respectively increased by 69.7% and 71.8% in small lesions and 35.6% and 33% in large lesions, respectively, when β-value was decreased from 500 to 100. ConclusionsAs the lesion size decreased, the optimum β-value decreased. In both studies, a β value of 400 would be optimal for reconstruction of small lesions, whereas for large lesions in phantom and clinical studies respectively, β-value of 600 and 500 is recommended.

A Hindmarsh‐Rose model perceptibility phantom containing inserts with various in vitro atherosclerotic plaque compositions was constructed and imaged on a clinical 64 slice multidetector (MDCT) system using 80 and 120 kVp settings and two other cone‐beam (CBCT) systems at 80 kVp. Perceptibility of the simulated lipid‐fibrotic plaque solutions in the images was evaluated by six observers. The effective doses of the protocols employed were estimated using phantom CTDI‐vol measurements placed at identical settings. The CBCT system allowed reduction in effective dose in comparison with the conventional MDCT system for imaging of the carotid plaque phantoms without degrading image quality. The CBCT dose was less than MDCT, with a mean dose of 1.14±0.01 mSv and 1.11±0.02 mSv for MDCT using two measuring techniques vs. 0.35±0.01 mSv for CBCT. The image quality analysis showed no significant differences in the contrast‐detail (C‐D) curves of the best performing CBCT vs. clinical MDCT false(p>0.05false) using a Mann‐Whitney U test. Results indicate that low‐tube‐potential CBCT may produce comparable C‐D resolution for phantom‐based representations of soft plaque types with respect to MDCT systems. This study suggests that the utility of low kVp CT techniques for evaluating carotid vulnerable atherosclerotic plaque merits further study.PACS numbers: 87.53.Bn, 87.57.N‐, 87.57.Q‐, 87.57.cj

Background Radiation dose metrics vary by the calibration reference phantom used to report doses. By convention, 16-cm diameter cylindrical polymethyl-methacyrlate phantoms are used for head imaging and 32-cm diameter phantoms are used for body imaging in adults. Actual usage patterns in children remain under-documented. Objective This study uses the University of California San Francisco International CT Dose Registry to describe phantom selection in children by patient age, body region and scanner manufacturer, and the consequent impact on radiation doses. Materials and methods For 106,837 pediatric computed tomography (CT) exams collected between Jan. 1, 2015, and Nov. 2, 2020, in children up to 17 years of age from 118 hospitals and imaging facilities, we describe reference phantom use patterns by body region, age and manufacturer, and median and 75th-percentile dose–length product (DLP) and volume CT dose index (CTDIvol) doses when using 16-cm vs. 32-cm phantoms. Results There was relatively consistent phantom selection by body region. Overall, 98.0% of brain and skull examinations referenced 16-cm phantoms, and 95.7% of chest, 94.4% of abdomen and 100% of cervical-spine examinations referenced 32-cm phantoms. Only GE deviated from this practice, reporting chest and abdomen scans using 16-cm phantoms with some frequency in children up to 10 years of age. DLP and CTDIvol values from 16-cm phantom-referenced scans were 2–3 times higher than 32-cm phantom-referenced scans. Conclusion Reference phantom selection is highly consistent, with a small but significant number of abdomen and chest scans (~5%) using 16-cm phantoms in younger children, which produces DLP values approximately twice as high as exams referenced to 32-cm phantoms