PURPOSE:To set national dose interventional reference levels (IRLs) for adults undergoing the most common cardiac electrophysiology and pacing procedures. MATERIALS AND METHODS:A national multicentre survey was performed in 33 French cardiac electrophysiology and pacing departments. Eleven standard image-guided interventional procedures in cardiac electrophysiology and pacing were analysed. Air Kerma (AK), kerma-area product (PKA) and fluoroscopy time (T) were recorded for 10 to 30 patients per procedure and per centre. IRLs were calculated as the 3rd quartiles and medians of distributions. RESULTS:A total of 4219 patients (70.4 ± 14.4 years old, 32% women) were included. IRLs were suggested for three dosimetric indicators in the eleven procedures. For endovascular implantation (pacemaker and defibrillator), IRLs increased with the complexity of procedures. In terms of PKA and T, IRLs were 4.10 Gy.cm2 and 5.5 min for single-chamber pacemakers, 11.50 Gy.cm2 and 16.5 min for bi-ventricular pacemakers, 2.25 Gy.cm2 and 4.0 min for single-chamber defibrillators and 12.90 Gy.cm2 and 18.0 min for bi-ventricular defibrillators. For all pacemaker procedures, left bundle branch area pacing significantly increased PKA, AK, and T values (p < 0.05). For ablations, the lowest IRLs were found for accessory pathway ablation (4.10 Gy.cm2 and 10.5 min) and the highest for ablation of persistent atrial fibrillation (12.65 Gy.cm2 and 15.5 min). For all ablations, the main energy source used was radiofrequency (>75% of procedures). For most procedures, the IRLs proposed were close to most of those already published, or lower. CONCLUSION:This national multicentre study reports IRLs for the most common image-guided interventional cardiac electrophysiology and pacing procedures.

BACKGROUND:Technological developments in computed tomography (CT) have increased the diversity of acquisition and reconstruction strategies available for clinical imaging. Task-based image quality metrics that account for patient-size variability are needed to characterize reconstructed image performance and support protocol optimization across clinically relevant imaging conditions. PURPOSE:To propose and evaluate a novel size-specific weighted detectability index (SSW-d'), a task-based image performance metric (d') that incorporates lesion contrast weighting and water-equivalent diameter variability for the characterization of CT images acquired at low dose. METHODS:First, a multi-sized image quality phantom was scanned on two CT systems: one photon-counting CT (PCCT, CT1) and one CT equipped with energy integrating detectors (EICT, CT2). Acquisitions were performed with a volume CT dose index (CTDIvol) of 3.2 mGy at 120kV without a tin filter (Sn), at Sn100 and Sn140kV. Second, acquisitions at 3.2 mGy were performed on CT1 using three reconstruction algorithms (FBP, QIR-2, QIR-4). Subsequently, five reconstruction kernels (Br32, Br44, Br56, Br68, and Br76) were evaluated at 1.1 mGy. A higher CTDIvol value of 6 mGy, combined with Br68 and QIR-4, was also tested. The detectability index values (d') were determined for two 10 mm diameter lesions according to two different levels of contrast, based on iodine and bone equivalent tissue. The SSW-d' was calculated for each CT system and for each individual task. Then, SSW-d' was expanded to include both tasks, applying contrast weights determined for each of them. RESULTS:On CT1, the highest SSW-d' values were 19.3 ± 0.3 and 6.9 ± 0.0, at 120 kV for bone and iodine rods, respectively. On CT2, the highest SSW-d' results were 19.0 ± 0.3 and 4.9 ± 0.0 at Sn100 kV for bone and iodine rods, respectively. The lowest values were at Sn140kV for both rods and CT systems. When encompassing both tasks, the maximum SSW-d' values were 10.05 ± 0.04 and 8.25 ± 0.03, respectively obtained at 120 kV for CT1 and at Sn100 kV for CT2. The results showed that the lowest SSW-d' values were at Sn140 kV for both CT systems. Comparison of acquisition and reconstruction parameters showed that the highest SSW-d' value was obtained using the Br32 kernel (17.6 ± 0.7), approximately twofold higher than that obtained at 6 mGy (8.6 ± 0.3). The lowest SSW-d' value (1.9 ± 0.1) was obtained with FBP, while the highest performance was achieved with QIR-4 reconstruction. CONCLUSIONS:A novel metric based on a size-specific weighted detectability index (SSW-d') was developed and evaluated for the characterization of reconstructed CT image performance across a range of patient-equivalent diameters and clinically relevant detection tasks. The proposed SSW-d' consolidates multiple detectability index measurements into a single descriptor that accounts for lesion contrast weighting and patient-size variability. The metric was sensitive to acquisition and reconstruction parameters and proved useful for identifying imaging conditions that maximize task-based performance in ultra-low-dose CT. These findings suggest that SSW-d' may serve as a practical tool for image-quality characterization and protocol optimization across clinically relevant imaging scenarios.

PURPOSE:The purpose of this study was to assess the image quality and dose reduction potential of ultra-high resolution (UHR) mode compared with standard mode, both available on a commercial photon-counting detector computed tomography (PCCT) scanner. MATERIALS AND METHODS:Images were acquired on a PCCT with a phantom using UHR and standard modes at three dose levels (3/6/12 mGy). Raw data were reconstructed using soft tissue (Br36) and bone (Br68) reconstruction kernels and 0.4-mm slice thickness. Noise power spectrum (NPS) and task-based transfer function (TTF) were calculated to assess noise magnitude, noise texture (fav), and spatial resolution (f50), respectively. Detectability indexes (d') were calculated to model the detection of two abdominal lesions for a Br36 soft tissue reconstruction kernel and three bone lesions for a Br68 bone reconstruction kernel. RESULTS:At all dose levels, noise magnitude values were lower with UHR than with standard mode (mean difference, -18.0 ± 2.6 [standard deviation (SD)] % for Br36 and -33.9 ± 2.3 [SD] % for Br68). Noise texture was lower with UHR than with standard mode (mean difference, -4.2 ± 0.9 [SD] % for Br36 and -16.0 ± 1.8 [SD] % for Br68). For the solid water insert and Br36, f50 values were similar for both UHR (0.34 ± [SD] 0.04 mm-1) and standard (0.33 ± [SD] 0.04 mm-1) modes. For Br68, f50 values were greater with UHR than with standard for iodine (mean difference, 18.5 ± 1.9 [SD] %) and bone (11.7 ± 5.7 [SD] %) inserts. For all simulated lesions, d' values were greater with UHR than with standard and, compared to standard, the dose reduction potential with UHR was -32.9 ± 0.0 (SD) % for abdominal lesions and -68.7 ± 3.2 (SD) % for bone lesions. CONCLUSION:Compared to the standard mode, the UHR mode offers lower noise levels and better detectability of abdominal and bone lesions, paving the way for potential dose reduction with PCCT in clinical applications.

PURPOSE:To compare the image quality obtained with an energy-integrating detector CT (EID-CT) and a photon-counting CT (PCCT) in ultra-low dose (ULD) chest CT protocols for three patient morphology configurations. MATERIALS AND METHODS:ULD-CT acquisitions were performed at Sn100 kV on PCCT and EID-CT using an image quality phantom. Different phantom sections were used to simulate standard, overweight and obese patients and the ULD levels were adapted to each section: 0.4, 0.8 and 1.6 mGy, respectively. Noise power spectrum (NPS) and task-based transfer function (TTF) were computed to assess noise magnitude, noise texture and spatial resolution, respectively. Detectability indexes (d') were computed to model the detection of a high-contrast solid nodule (HCN). RESULTS:At all dose levels, noise magnitude values were significantly lower with PCCT than with EID-CT (-8.9 ± 0.4 %; p < 0.05). Values of average NPS spatial frequencies were significantly higher (p < 0.05) with PCCT (0.446 ± 0.010 mm-1) than with EID-CT mode (0.323 ± 0.011 mm-1). For the air insert, TTF values at 50 % were significantly lower for PCCT (0.719 ± 0.045 mm-1) than with EID-CT (0.916 ± 0.030 mm-1) at 1.6 mGy but similar for other dose levels (p < 0.05). For the simulated chest lesion, d' values were significantly higher (p < 0.05) with PCCT than with EID-CT. The improvements in d' values was 23.6 ± 5.5 % for HCN. CONCLUSION:Compared with EID-CT, using PCCT makes it possible to reduce noise, improve noise texture and, above all, improve the detection of simulated high-contrast thoracic lesion in ULD CT protocols.

Background Figures of Merit (FOM) based on signal-difference-to-noise ratio (FOMSDNR) are commonly used to determine optimal technical parameters in digital radiography.However, this does not evaluate image quality for a specific clinical task nor account for spatial frequency response. Purpose To evaluate a new FOM based on the detectability index (FOMd') using the International Atomic Energy Agency (IAEA) methodology. To compare the optimum parameters obtained from FOMd' and FOMSDNR on an anthropomorphic test-object. Methods Several settings were evaluated involving six additional filtrations from none to 1 mm Cu, two tube voltages (80 and 110 kV), and four incident air kerma at the detector(1, 2, 3, 4 mu Gy). FOMd' and FOMSDNR were determined on a Clisis Exel DRF unit for the IAEA test-object. The maximum FOM values determined the optimum settings. They were used to image an anthropomorphic test-object modified with the presence of a lesion, either in homogeneous or heterogeneous backgrounds. Three radiologists scored the images with a 5-point Likert scale. A Mann-Whitney test was used to compare overall image scoring for both backgrounds. Results The highest FOM values were at: 80 kV, 2 mu Gy, 1 mm Cu for FOMSDNR and 80 kV, 1 mu Gy, and 0.3 mm Cu+2 mm Al for FOMd'. Overall image scorings were statistically higher for FOMd' with homogenous background: 4.6 +/- 0.5 vs 3.7 +/- 1.0 (p = 0.013) and statistically similar for FOMs with heterogeneous background: 3.5 +/- 1.3 vs 3.9 +/- 0.8 (p = 0.540). Conclusion A novel FOM based on d' was introduced and compared with FOMSDNR, giving better and similar results on homogeneous and heterogeneous backgrounds, respectively. Since the d' has the advantage of selecting a size-specific lesion for detection, the FOMd' opens the perspective for task-based optimization in digital radiography using the IAEA methodology.

Background/Objectives: To define and evaluate a radiation dose optimization process for chest computed tomography (CT) imaging. Methods: Data from unenhanced and enhanced chest CT acquisitions performed between June 2018 and January 2020 in adult patients were included in the study. Images were acquired on a Siemens SOMATOM® Definition Edge CT. Dose values, including Dose.Length Product (DLP) and Volume CT Dose Index (CTDIvol), were collected. Low doses (LDs, 25th percentiles), achievable doses (ADs, 50th percentiles), and diagnostic reference levels (DRLs, 75th percentiles) were calculated before and after parameter modifications. A process was defined and applied to patient data. For unenhanced chest CT, data were differentiated according to three groups: high dose (HD), optimized dose (OD), and ultra-low dose (ULD). Dosimetric changes between protocols were expressed as mean CTDIvol % (CI95%). A Mann and Whitney statistical test was used. The diagnostic quality score (DQS) of a subset of 70 randomly selected CT examinations was evaluated by one radiologist. The DQS was scored according to a three-point Likert scale: (1) poor (definite diagnosis impossible), (2) fair (evaluation of major findings possible), and (3) excellent (exact diagnosis possible). Results: Data were collected from 1929 patients. For unenhanced chest CT protocols, only one process loop was run. A dose comparison between the chest CT protocol before the use of the process and the three groups showed a decrease of −38.3% (9.7%) and −93.4% (24.2%) for OD and ULD, respectively, and an increase of +29.4% (4.7%) for HD. For the enhanced chest CT protocol, two optimization loops were performed, and they resulted in a mean dose reduction of −50.0% (2.6%) compared to the pre-optimization protocol. For all protocols, the DQS was greater than or equal to 2. Conclusions: We proposed a radiation dose optimization process for chest CT that could significantly reduce the dose without compromising diagnosis.

Background/Objectives: Radiography is an essential and low-cost diagnostic method in pulmonary medicine that is used for the early detection and monitoring of lung diseases. An adequate and consistent image quality (IQ) is crucial to ensure accurate diagnosis and effective patient management. This pilot study evaluates the feasibility and effectiveness of the International Atomic Energy Agency (IAEA)’s remote and automated quality control (QC) methodology, which has been tested in multiple imaging centers. Methods: The data, collected between April and December 2022, included 47 longitudinal data sets from 22 digital radiographic units. Participants submitted metadata on the radiography setup, exposure parameters, and imaging modes. The database comprised 968 exposures, each representing multiple image quality parameters and metadata of image acquisition parameters. Python scripts were developed to collate, analyze, and visualize image quality data. Results: The pilot survey identified several critical issues affecting the future implementation of the IAEA method, as follows: (1) difficulty in accessing raw images due to manufacturer restrictions, (2) variability in IQ parameters even among identical X-ray systems and image acquisitions, (3) inconsistencies in phantom construction affecting IQ values, (4) vendor-dependent DICOM tag reporting, and (5) large variability in SNR values compared to other IQ metrics, making SNR less reliable for image quality assessment. Conclusions: Cross-comparisons among radiography systems must be taken with cautious because of the dependence on phantom construction and acquisition mode variations. Awareness of these factors will generate reliable and standardized quality control programs, which are crucial for accurate and fair evaluations, especially in high-frequency chest imaging.

An image-quality CT phantom was scanned with three different 3D X-ray imaging guidance devices in the operating theatre: O-Arm, Loop-X, and Airo TruCT. Default acquisition and reconstruction parameters for lumbar spine procedures were used on each device. The tube current was set to a dose level of around 27 mGy. A task-based image quality assessment was performed by calculating the noise power spectrum (NPS) and task transfer function (TTF). A detectability index (d’) was calculated for three simulated bone lesions. The noise magnitude of the O-Arm was higher than the Airo TruCT, and the Loop-X had higher noise than the Airo TruCT. The highest average NPS frequency was for the O-Arm images, and the lowest was for the Loop-X. The TTFs at 50% values were similar for the Airo TruCT and Loop-X devices. Compared to Airo TruCT, the TTF at 50% value increased with the O-Arm by 53.12% and 41.20% for the Teflon and Delrin inserts, respectively. Compared to Airo TruCT, the d’ value was lower with Loop-X by −26.73%, −27.02%, and −23.95% for lytic lesions, sclerotic lesions, and high-density bone, respectively. Each 3D-imaging spine surgery guidance device has its own strengths and weaknesses in terms of image quality. Cone-beam CT systems apparently offer the best compromise between noise and spatial resolution for spine surgery.

Intraoperative fluoroscopy use is essential during spinal fusion procedures. The amount of radiation dose should always be minimized. This study aimed to determine the feasibility of halving the frame rate from 12.5 to 6.25 frames per second (fps) and to quantify the reduction in the risk of developing radiation-induced cancer. This pilot study included 34 consecutive patients operated for open lumbar posterolateral fusion (PLF) with or without transforaminal lumbar interbody fusion (TLIF). C-arm modes were changed from half-dose (12.5 frames per second (fps), group I) to quarter-dose (6.25 fps, group II). Age, body mass index, surgical procedure, number of treated levels, and complications were collected. Kerma area product (KAP), cumulative air kerma (CAK), and fluoroscopy time were compared. Effective dose and radiation-induced cancer risk were estimated. Eighteen and 16 patients were, respectively, included in group I and II. Demographic, surgical data, and fluoroscopy time were similar in both groups. However, CAK, KAP, and effective dose were significantly lower in group II, respectively, 0.56 versus 0.41 mGy (p = 0.03), 0.09 versus 0.06 Gy cm2 (p = 0.04), and 0.03 versus 0.02 mSv (p = 0.04). Radiation-induced cancer risk decreased by 47.7

This study aimed to evaluate the impact of three two-dimensional (2D) mammographic acquisition techniques on image quality and radiation dose in the presence of silicone breast implants (BIs). Then, we propose and validate a new International Atomic Energy Agency (IAEA) phantom to reproduce these techniques. Images were acquired on a single Hologic Selenia Dimensions® unit. The mammography of the left breast of a single clinical case was included. Three methods of image acquisition were identified. They were based on misused, recommended, and reference settings. In the clinical case, image criteria scoring and the signal-to-noise ratio on breast tissue (SNRBT) were determined for two 2D projections and compared between the three techniques. The phantom study first compared the reference and misused settings by varying the AEC sensor position and, second, the recommended settings with a reduced current-time product (mAs) setting that was 13% lower. The signal-difference-to-noise ratio (SDNR) and detectability indexes at 0.1 mm (d’ 0.1 mm) and 0.25 mm (d’ 0.25 mm) were automatically quantified using ATIA software. Average glandular dose (AGD) values were collected for each acquisition. A statistical analysis was performed using Kruskal–Wallis and corrected Dunn tests (p < 0.05). The SNRBT was 2.6 times lower and the AGD was −18% lower with the reference settings compared to the recommended settings. The SNRBT values increased by +98% with the misused compared to the recommended settings. The AGD increased by +79% with the misused settings versus the recommended settings. The median values of the reference settings were 5.8 (IQR 5.7–5.9), 1.2 (IQR 0.0), 7.0 (IQR 6.8–7.2) and 1.2 (IQR 0.0) mGy and were significantly lower than those of the misused settings (p < 0.03): 7.9 (IQR 6.1–9.7), 1.6 (IQR 1.3–1.9), 9.2 (IQR 7.5–10.9) and 2.2 (IQR 1.4–3.0) mGy for the SDNR, d’ 0.1 mm, d’ 0.25 mm and the AGD, respectively. A comparison of the recommended and reduced settings showed a reduction of −6.1 ± 0.6% (p = 0.83), −7.7 ± 0.0% (p = 0.18), −6.4 ± 0.6% (p = 0.19) and −13.3 ± 1.1% (p = 0.53) for the SDNR, d’ 0.1 mm, d’ 0.25 mm and the AGD, respectively. This study showed that the IAEA phantom could be used to reproduce the three techniques for acquiring 2D mammography images in the presence of breast implants for raising awareness and for educational purposes. It could also be used to evaluate and optimize the manufacturer’s recommended settings.

BACKGROUND:Recently, a second generation of split filter dual-energy CT (SFCT) platform has been developed. The thicknesses of the gold and tin filters used to obtain both low- and high-energy spectra have been changed. These differences in filter thickness may affect the spectral separation between the two spectra and thus the quality of spectral images.PURPOSE:To compare the spectral performance of two Split-Filter Dual-Energy CT systems (SFCT-1st and SFCT-2nd ) on virtual monoenergetic images (VMIs) and iodine map.METHODS:A Multi-Energy CT phantom was scanned on two SFCT with a tube voltage of 120 kVp for both systems (SFCT-1st -120 and SFCT-2nd -120) and 140 kVp only for the second generation (SFCT-2nd -140). Acquisitions were performed on the phantom with a CTDIvol close to 11 mGy. Noise power spectrum (NPS) and task-based transfer function (TTF) were evaluated on VMIs from 40 to 70 keV. A detectability index (d') was computed to assess the detection of two contrast-enhanced lesions on VMIs. Hounsfield Unit (HU) accuracy was assessed on VMIs and the accuracy of iodine concentration was assessed on iodine maps.RESULTS:For all keV, noise magnitude values were lower with the SFCT-2nd -120 than with the SFCT-1st -120 (on average: -22.5 ± 2.9%) and higher with the SFCT-2nd -140 than with the SFCT-2nd -120 (on average: 25.0 ± 6.2%). Average NPS spatial frequencies (fav ) were lower with the SFCT-1st -120 than with the SFCT-2nd -120 (-6.0 ± 0.5%) and the SFCT-2nd -140 (-3.6 ± 1.6%). Similar TTF50% values were found for both systems and both kVp for blood and iodine inserts at 2 mg/mL (0.29 ± 0.01 mm-1 ) and at 4 mg/mL (0.31 ± 0.01 mm-1 ). d' values peaked at 40 keV for the SFCT-2nd and at 70 keV for the SFCT-1st . Highest d' values were found for the SFCT-2nd -120 for both simulated lesions. Accuracy of HU values and iodine concentration was higher with the SFCT-2nd than with the SFCT 1st .CONCLUSION:Compared to the SFCT-1st , with similar spatial resolution and noise texture values, the SFCT-2nd -120 exhibited the lowest values for noise magnitude, the highest detectability index values, and more accurate HU values and iodine concentrations.

Endovascular treatments of complex aortic and aortoiliac aneurysms are the most radiant procedures in vascular surgery. The objective of this study was to assess exposure to ionizing radiation during the placement of fenestrated (FEVAR) or branched (BEVAR) thoracoabdominal aortic or branched aortoiliac (BEVAR) stentgrafts using a "very low dose" protocol (VLD).

Purpose: The purpose of this study was to assess the impact of a tin filter on the image quality of ultra-low dose (ULD) chest computed tomography (CT) on three different CT systems.Materials and methods: An image quality phantom was scanned on three CT systems including two split-filter dual-energy CT (SFCT-1 and SFCT-2) scanners and one dual-source CT scanner (DSCT). Acquisitions were performed with a volume CT dose index (CTDIvol) of 0.4 mGy, first at 100 kVp without tin filter (Sn), and second, at Sn100/Sn140 kVp, Sn100/Sn110/Sn120/Sn130/Sn140/Sn150 kVp and Sn100/Sn150 kVp for SFCT-1, SFCT-2 and DSCT respectively. Noise-power-spectrum and task-based transfer function were computed. The detect ability index (d') was computed to model the detection of two chest lesions.Results: For DSCT and SFCT-1, noise magnitude values were higher with 100kVp than with Sn100 kVp and with Sn140 kVp or Sn150 kVp than with Sn100 kVp. For SFCT-2, noise magnitude increased from Sn110 kVp to Sn150 kVp and was higher at Sn100 kVp than at Sn110 kVp. For most kVp with the tin filter, the noise amplitude values were lower than those obtained at 100 kVp. For each CT system, noise texture and spatial resolution values were similar with 100 kVp and with all kVp used with a tin filter. For all simulated chest lesions, the highest d' values were obtained at Sn100 kVp for SFCT-1 and DSCT and at Sn110 kVp for SFCT-2.Conclusion: For ULD chest CT protocols, the lowest noise magnitude and highest detectability values for simulated chest lesions are obtained with Sn100 kVp for the SFCT-1 and DSCT CT systems and at Sn110 kVp for SFCT-2.(c) 2023 Societe francaise de radiologie. Published by Elsevier Masson SAS. All rights reserved.

Complex endovascular aneurysm repair (cEVAR) delivers high levels of radiation, and the radiation dose for cEVAR may cross the threshold value of 500 Gy·cm2 above which skin injury may occur. 1 Hertault A. Bianchini A. Amiot S. Chenorhokian H. Laurent-Daniel F. Chakfé N. et al. Comprehensive literature review of radiation levels during endovascular aortic repair in cathlabs and operating theatres. Eur J Vasc Endovasc Surg. 2020; 60: 374-385 Abstract Full Text Full Text PDF PubMed Scopus (11) Google Scholar As highlighted by the recent radioprotection guidelines of the European Society for Vascular Surgery (ESVS), 2 Modarai B. Haulon S. Ainsbury E. Böckler D. Vano-Carruana E. Dawson J. et al. European Society for Vascular Surgery (ESVS) 2023 clinical practice guidelines on radiation safety. Eur J Vasc Endovasc Surg. 2023; 65: 171-222 Abstract Full Text Full Text PDF PubMed Scopus (38) Google Scholar the use of a low dose imaging protocol and pulse mode fluoroscopy should be explored. In this report, the feasibility and efficiency of using a two frames per second (fps) fluoroscopy optimised protocol during cEVAR was evaluated.

The purpose of this study was to compare the quality of low-energy virtual monoenergetic images (VMIs) obtained with three Dual-Energy CT (DECT) platforms according to the phantom diameter. Three sections of the Mercury Phantom 4.0 were scanned on two generations of split-filter CTs (SFCT-1st and SFCT-2nd) and on one Dual-source CT (DSCT). The noise power spectrum (NPS), task-based transfer function (TTF), and detectability index (d’) were assessed on VMIs from 40 to 70 keV. The highest noise magnitude values were found with SFCT-1st and noise magnitude was higher with DSCT than with SFCT-2nd for 26 cm (10.2% ± 1.3%) and 31 cm (7.0% ± 2.5%), and the opposite for 36 cm (−4.2% ± 2.5%). The highest average NPS spatial frequencies and TTF values at 50% (f50) values were found with DSCT. For all energy levels, the f50 values were higher with SFCT-2nd than SFCT-1st for 26 cm (3.2% ± 0.4%) and the opposite for 31 cm (−6.9% ± 0.5%) and 36 cm (−5.6% ± 0.7%). The lowest d’ values were found with SFCT-1st. For all energy levels, the d’ values were lower with DSCT than with SFCT-2nd for 26 cm (−6.2% ± 0.7%), similar for 31 cm (−0.3% ± 1.9%) and higher for 36 cm (5.4% ± 2.7%). In conclusion, compared to SFCT-1st, SFCT-2nd exhibited a lower noise magnitude and higher detectability values. Compared with DSCT, SFCT-2nd had a lower noise magnitude and higher detectability for the 26 cm, but the opposite was true for the 36 cm.

Purpose To describe the creation process of a new breast phantom specifically designed to monitor quality control (QC) metrics consistency over several months in digital breast tomosynthesis (DBT). Methods The semi-anthropomorphic Tomomam(R) phantom was designed and evaluated twice monthly on a single Hologic Selenia Dimensions(R) unit over 5 months. The phantom is manufactured in a one-piece epoxy resin homogeneous material as the basis for manufacturing, simulating breast tissue as 50% equivalent glandular (GL)/50% equivalent adipose (AD) and compressed thickness of 60 mm. The distribution of test objects on different planes inside the phantom should allow the quantification of 10 image quality metrics: reproducibility, signal difference-to-noise ratio (SDNR), geometric distortions in the plane, missing or added tissue at chest wall, at the top and bottom of images stack and lateral sides, in-plane homogeneity, image scoring, artifact spread function (ASF), geometric distortions in the volume. SDNR was quantified according to GL and AD tissues. Tolerance criteria per parameter were described to analyze results over the study time. Results Mean scores were equal to 15.4, 15.0, and 11.6 for masses, microcalcifications, and fibers, respectively. A large difference between GL and AD tissues for SDNR metrics was noted over the study time: the best results were obtained from GL tissues. Both geometric distortions and local homogeneity in the plane conformed to expected values. The mean volume value of the triangular prism was 11.3% greater than the expected value due to a reconstruction height equal to 66 mm instead of 60 mm. Conclusions In this study, we monitored several QC metrics discriminating GL and AD tissues by using a new breast phantom developed by us. The preliminary clinical tests demonstrated that the Tomomam(R) phantom could be used to reliably and efficiently track 10 QC metrics with a single acquisition. More data need to be acquired to refine tolerance criteria for some metrics.

In 2017, El-Sayed et al.1 reported worrying consequences of occupational radiation exposure such as an acute DNA damage response for fenestrated or branched endovascular aortic repair (F/B-EVAR) operators. This study highlighted the insufficient radioprotection of operators when using widely accepted2 traditional personal protective equipment (PPE), which leaves major body parts such as legs, head, and arms uncovered. Therefore, improving ancillary shielding barriers (ASB) is paramount. However, the reality is that surgeons in many centres are not well protected against radiation.

Background: The role and performance of chest CT in the diagnosis of the coronavirus disease 2019 (COVID-19) pandemic remains under active investigation. Purpose: To evaluate the French national experience using chest CT for COVID-19, results of chest CT and reverse transcription polymerase chain reaction (RT-PCR) assays were compared together and with the final discharge diagnosis used as the reference standard. Materials and Methods: A structured CT scan survey (NCT04339686) was sent to 26 hospital radiology departments in France between March 2, 2020, and April 24, 2020. These dates correspond to the peak of the national COVID-19 epidemic. Radiology departments were selected to reflect the estimated geographic prevalence heterogeneities of the epidemic. All symptomatic patients suspected of having COVID-19 pneumonia who underwent both initial chest CT and at least one RT-PCR test within 48 hours were included. The final discharge diagnosis, based on multiparametric items, was recorded. Data for each center were prospectively collected and gathered each week. Test efficacy was determined by using the Mann-Whitney test, Student t test, chi(2) test, and Pearson correlation coefficient. P <.05 indicated a significant difference. Results: Twenty-six of 26 hospital radiology departments responded to the survey, with 7500 patients entered; 2652 did not have RT-PCR test results or had unknown or excess delay between the RT-PCR test and CT. After exclusions, 4824 patients (mean age, 64 years +/- 19 [standard deviation], 2669 male) were included. With final diagnosis as the reference, 2564 of the 4824 patients had COVID-19 (53%). Sensitivity, specificity, negative predictive value, and positive predictive value of chest CT in the diagnosis of COVID-19 were 2319 of 2564 (90%; 95% CI: 89, 91), 2056 of 2260 (91%; 95% CI: 91, 92), 2056 of 2300 (89%; 95% CI: 87, 90), and 2319 of 2524 (92%; 95% CI: 91, 93), respectively. There was no significant difference for chest CT efficacy among the 26 geographically separate sites, each with varying amounts of disease prevalence. Conclusion: Use of chest CT for the initial diagnosis and triage of patients suspected of having coronavirus disease 2019 was successful. (C) RSNA, 2020

An efficient nano-sized delivery system is presented here allowing the immobilized, picolinium-tethered organic ligand to be released by X-ray irradiation. A marked difference was observed in the fragmentation efficiency by using conventional Cs-137 vs. pulsed sources.