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To investigate minimal required sub milli-Sievert (mSv) ultra-low dose CT and corresponding tube current and voltage for reliable attenuation correction and semi- quantitation in 18F-FDG PET-CT in an effort for radiation dose reduction. Methods: We performed a PET-CT investigational study using a NEMA torso phantom containing six spheres (diameter: 10, 13, 17, 22, 28, 37 mm) filled with a fixed concentration of 60 kBq/ml and a background of 15 kBq/ml of 18F-FDG. Two sets of PET images, separated by 2 hours, were acquired for 3 minutes in a single bed position using 3-D mode with and without time-of-flight in a GE D-690 scanner. Several sets of CT images were acquired for attenuation correction with different combinations of tube voltage (80, 100, 120 kVp) and effective mAs (tube current-time product divided by pitch), using the maximum beam collimation (64 x 0.625 mm). The lowest CT acquisition technique available on this scanner is 10 mA, 0.4 s and 1.375 for the tube current, tube rotation time and pitch, respectively. The CT radiation dose was estimated based on the computed tomography dose index volume (CTDIvol) measurements performed following the standard methodology and the Imaging Performance Assessment of CT Scanners (ImPACT) calculator. Each of the CT techniques was used for attenuation correction to the same PET acquisition, using ordered-subset expectation maximum (OSEM) algorithm with 24 subsets and 2 iterations. The maximal and average radioactivity (kBq/ml) and standardized uptake values (SUV) of the spheres were measured. The minimal ultra-low dose CT for attenuation correction was determined by reproducible SUV measurements (±10%) compared to our reference CT protocol of 100 kVp and 80 mA for 0.5 s rotation. Results: The minimal ultra-low dose of CT for reproducible quantification in all spheres (

The purpose of the present work was to evaluate performance in pulmonary nodule detection, reading times and patient doses for ultra-low dose computed tomography (ULD-CT), standard dose chest CT (SD-CT), and digital radiography (DR). Pulmonary nodules were simulated in an anthropomorphic lung phantom. Thirty cases, 18 with lesions (45 total lesions of 3–12 mm) and 12 without lesions were acquired for each imaging modality. Three radiologists interpreted the cases in a free-response study. Performance was assessed using the JAFROC figure-of-merit (FOM). Performance was not significantly different between ULD-CT and SD-CT (FOMs: 0.787 vs 0.814; ΔFOM: 0.03), but both CT techniques were superior to DR (FOM: 0.541; ΔFOM: 0.31 and 0.28). Overall, the CT modalities took longer time to interpret than DR. ULD chest CT may serve as an alternative to both SD-CT and conventional radiography, considerably reducing dose in the first case and improving diagnostic accuracy in the second.

This study aimed to evaluate the efficacy and safety of ultra-low-dose estradiol plus dydrogesterone for vasomotor symptoms in postmenopausal women in China (trial registration CTR20160689).A total of 332 patients were randomized to continuous combined estradiol 0.5 mg + dydrogesterone 2.5 mg or placebo for 12 weeks. The primary efficacy endpoint was change in the number of hot flushes per day from baseline to end of treatment. Secondary efficacy endpoints included change in the number of moderate-to-severe hot flushes per day, menopausal symptoms from baseline and quality of life.Between baseline and end of treatment, change in the mean number of hot flushes per day was -5.9 (95% confidence interval [CI] - 6.6, -5.2) with estradiol + dydrogesterone and -4.5 (95% CI -5.1, -3.8) with placebo, with a mean difference of -1.4 hot flushes per day (95% CI -2.2, -0.7;Continuous combined estradiol 0.5 mg + dydrogesterone 2.5 mg reduced hot flushes in postmenopausal women in China. This ultra-low-dose regimen provides an additional option for women experiencing the vasomotor symptoms of menopause. These data are consistent with previous results in other populations.

Purpose: To evaluate the feasibility of ultra-low dose 80 kVp CT for the evaluation of inflammatory bowel disease (IBD) in a rabbit model and to investigate the effect of two different iterative reconstruction (IR) algorithms on 80 kVp CT in terms of image quality and diagnostic performance in comparison with same session conventional 120 kVp images.Materials and Methods: This study was approved by the Animal Care and Use Committee of our hospital. Twenty-eight New Zealand white rabbits were randomly divided into two groups: IBD group (n=18) and a control group (n=10). To create an acute IBD model, 3mL of a 5% w/v tri-nitrobenzene sulfonic acid solution was administered to the sigmoid colon of the rabbits. CT was performed at 80 kVp and 120 kVp and was reconstructed using filtered back projection (FBP), hybrid statistic-based IR, and full IR algorithms for 80 kVp and using FBP only for 120 kVp. Effective radiation dose, image noise, image quality, and diagnostic performance by two reviewers were recorded and compared using repeated measure analysis of variance, McNemar test, and receiver operating curve (ROC) analysis.Results: Mean effective radiation dose of 80 kVp CT (0.05 mSv) was significantly lower than that (0.285 mSv) of 120 kVp CT. Mean image noise was highest in the 80 kVp FBP setting (60.36) but significantly decreased with IR algorithms (47.02 with hybrid IR and 12.92 with full IR) (P

Aim. Determination of the possibility of reliable quantitative assessment of the coronary calcium index based on ultra-low-dose computed tomography (ultra-LDCT) which used in Moscow Lung Cancer Screening project.Material and methods. The study included the results of 254 ultra-LDCT studies conducted as part of the Moscow lung cancer screening project. For compare the parameters of coronary calcium on different images used 16 pairs of ultra-LDCT images with a slice thickness of 1 mm and CT images with a slice thickness of 3 mm, performed without ECG synchronization, performed with an interval of less than 10 days, as well as 18 pairs of ultra-LDCT with a slice thickness of 1 mm and CT with ECG synchronization with a slice thickness of 3 mm, performed on the same day after execution. Analysis of DICOM 3.0 standard images was performed. Quantitative indicators of coronary calcium in patients from lung cancer screening were analyzed, a comparative analysis of the calcium index for Agatstone, Volume, Mass, and using the CAC-DRS scale (assessment of the degree of calcification by scores from 0 to 3 and the number of affected arteries from 0 to 4 points) was performed.Results. Evaluation ultra-LDCT with a slice thickness in 1 mm and with a CT scan with slice thickness in 3 mm with and without ECG-synchronization for the presence of coronary calcium, and subsequent rating according to the index Agatston, Volume, Mass, as the total coronary calcium and for each coronary artery (right, left, left descending, left circumflex) received the complete data correlation (Pearson's - 1), with full correlation (Spearman's >0.9), with good rank correlations (>0,9). Compare qualitative (CAC-DRS V) and quantitative (CAC-DRS A) estimates on ultra-LDCT with CT with ECG synchronization in the same patients show a complete correlation of data was obtained (Pearson's formula - 1), with a complete correlation (Spearman's formula - 1).Conclusion. Coronary calcium which detected in lung cancer screening subjects should be included in the overall decision-making process for further routing of patients (cardiologist, interventional surgeon, pulmonologist, therapist). Ultra-LDCT is a method that has high diagnostic accuracy in detecting and evaluating the prevalence of coronary calcium in comparison with standard CT with and without ECG synchronization, as demonstrated in our study. Evaluation of coronary calcium according to ultra-LDCT without ECG synchronization used in screening, preferably with a 1 mm slice thickness. Despite the fact that the gold standard is CT with ECG synchronization with a 3 mm slice thickness, the diagnostic significance of ultra-LDCT which used in lung cancer screening is high in relation to detecting coronary artery calcification.

Multi-detector computed tomography (MDCT) is superior in fracture detection than conventional radiography; however, dose is increased. Cone-beam computed tomography (CBCT) offers higher spatial resolution and lower dose than MDCT. Manufacturers offer an ultra-low-dose algorithm. This study compares the diagnostic accuracy of the ultra-low-dose CBCT (ULDCBCT) with that of the standard-dose CBCT (SDCBCT). In total, 64 patients were scanned with both the SDCBCT and the ULDCBCT protocols. Both studies were reported by two consultant radiologists with fellowship training in emergency radiology separated in time. The reporter recorded a diagnosis of fracture or normal and diagnostic confidence using a 5-point Likert scale. The gold standard was taken as the SDCBCT. Reporters were blinded to the indication and the SDCBCT report. Cases of discrepancy were resolved by consensus. There were 34 fractures and 30 cases had no fracture. Several fractures were missed using the UDCBCT, and there were also several cases of overdiagnosis. ULD was inferior to SD for fracture diagnosis (p

Introduction: Adjuvants are used in conjunction with local anaesthetics for brachial plexus block to quicken onset, prolong duration and augment the quality of anaesthesia. Objectives: The study aims to evaluate the effect of adding ultra-low dose naloxone to bupivacaine on the duration of postoperative analgesia. Methodology: A prospective, randomized, double-blind study was conducted including forty American Society of Anesthesiologists Physical Status (ASA PS) I and II patients of either sex between 15 and 65 years of age scheduled for upper limb surgery. They were randomized into two groups. Group BN received a mixture of 0.33% plain bupivacaine with ultra-low dose naloxone (100 ng) and group BS received 0.33% plain bupivacaine with saline. The procedure was standardized in both groups. The onset of sensory and motor block were assessed with pinprick sensation and muscle power respectively. Visual Analogue Score (VAS) was used to assess the pain at 1, 2, 4, 8 and 12 hours postoperatively. Result: The patients were comparable with respect to age, sex, ASA PS, baseline hemodynamic and respiratory parameters and duration of surgery. The mean duration of analgesia in group BN was significantly longer (610.7±125.4 mins) as compared to group BS (354.3±59.6 mins) (p

INTRODUCTION: Ischemic stroke treatment has advanced in the last two decades and intravenous thrombolysis is now considered the standard of care for selected patients. Recanalization can also be achieved by mechanical endovascular treatment for patients with large vessel occlusions. Complicating treatment-related symptomatic intracerebral hemorrhage and prolonged needle-to-recanalization times have been identified as major determinants of poor three-month functional outcomes. A hybrid mechanical-thrombolytic system with a patch imbued with an ultra-low dose of thrombolytic agents loaded onto a stent-retriever has been developed. METHODS: In this study, the in situ dose–response relationship of the thrombolytic patch imbued with up to 1000 IU of urokinase plasminogen activator (uPA) was quantified using Raman spectroscopy. RESULTS: Thrombi of up to 400 μm thickness dissolved within 15 min when patches imbued with

PurposeStudies have evaluated imaging modalities with a lower radiation dose than standard-dose CT (SD-CT) for chest examination. This systematic review aimed to summarize evidence on diagnostic accuracy of these modalities – low-dose and ultra-low-dose CT (LD- and ULD-CT) – for chest pathology.MethodOvid-MEDLINE, Ovid-EMBASE and the Cochrane Library were systematically searched April 29th–30th, 2019 and screened by two reviewers. Studies on diagnostic accuracy were included if they defined their index tests as ‘LD-CT’, ‘Reduced-dose CT’ or ‘ULD-CT’ and had SD-CT as reference standard. Risk of bias was evaluated on study level using the Quality Assessment of Diagnostic Accuracy Studies-2. A narrative synthesis was conducted to compare the diagnostic accuracy measurements.ResultsOf the 4257 studies identified, 18 were eligible for inclusion. SD-CT (3.17 ± 1.47 mSv) was used as reference standard in all studies to evaluate diagnostic accuracy of LD- (1.22 ± 0.34 mSv) and ULD-CT (0.22 ± 0.05 mSv), respectively. LD-CT had high sensitivities for detection of bronchiectasis (82–96%), honeycomb (75–100%), and varying sensitivities for nodules (63–99%) and ground glass opacities (GGO) (77–91%). ULD-CT had high sensitivities for GGO (93–100%), pneumothorax (100%), consolidations (90–100%), and varying sensitivities for nodules (60–100%) and emphysema (65–90%).ConclusionThe included studies found LD-CT to have high diagnostic accuracy in detection of honeycombing and bronchiectasis and ULD-CT to have high diagnostic accuracy for pneumothorax, consolidations and GGO. Summarizing evidence on diagnostic accuracy of LD- and ULD-CT for other chest pathology was not possible due to varying outcome measures, lack of precision estimates and heterogeneous study design and methodology.

Active development of the "anti-aging medicine", attempts to slow down biological (including vascular) aging led to the creation of new pharmaceuticals including menopausal hormone therapy. The vascular wall protective mechanism of the hormones is not completely clear, but it was shown that natural estrogens are able to control the condition of the vascular wall, prevent platelet adhesion, control a range of metabolic and trophic and energy processes in the endothelium of the vascular wall, producing antithrombogenic factors, namely their inhibition contributes to the development of atherosclerosis. It is known that standard and low-dose estrogen may restore the impaired antithrombogenic potential of the vascular wall, provided its initial reduction does not exceed 20%. The issue of the role and possibilities of correction of the antithrombogenic activity of the vascular wall with ultra-low dose estradiol remained unresolved. As a "clinical model" for the study of this issue, we formed 2 groups of patients: in the study group patients received ultra-low dose estradiol plus dydrogesterone, subjects from the control group received beta-alanine. Three-year follow-up showed a decrease in antithrombogenic activity of the vascular wall in control subjects after 2 and 3 years of follow-up according to the M.V. Baluda's test versus subjects treated with ultra-low dose estrogen plus dydrogesterone. The decrease of the relative risk of reduction of the antithrombogenic activity of the vascular wall with the use of ultra-low dose estrogen plus dydrogesterone during the first two years was 2.3 times, and during the 3 years of follow-up 3.8 times versus control. Thus, prescribing only ultra-low dose estradiol plus dydrogesterone for patients with normal antithrombogenic activity of the vessel wall at baseline reliably lowers the risk of long-term reduction of antithrombogenic potential of the vascular wall.

BACKGROUND Combined oral contraceptive pills are the most effective temporary contraception methods and are used by approximately 60 - 80 million eligible women throughout the world. It is the oestrogen component of the combined oral contraceptive (COC) which is responsible for the undesirable and serious side effects such as deep vein thrombosis (DVT) and pulmonary embolism (PE). So, there has been a constant effort to reduce the amount of ethinyl estradiol (EE) while maintaining its contraceptive efficacy. This study was aimed at studying the safety and efficacy of ultralow dose combined oral contraceptive (containing 15 mcg EE + 60 mcg gestodene) in rural Indian women. METHODS The study was done at Rama Medical College, Mandhana, Kanpur, among 70 patients who fulfilled the inclusion criteria. The patients were given ULDOCP and followed up for 6 months. The patients followed the regime of one tablet of ULDOCP daily from day 1 to day 24 of the menstrual cycle with 4 days pill free period before starting the next pack. RESULTS Seventy patients completed the study till 3 months and fifty patients completed the study till 6 months. Break through bleeding (BTB) was the only prominent side effect which was reduced in subsequent cycles and our patients tolerated this well. No pregnancy resulted. The ULDCOP was very well accepted by those women who were counselled about possible side effects and their harmless nature before starting the study. It was found that the users were satisfied with the use of ULDOCP. All side effects were significantly lower after 2 months of use and there were no serious side effects. CONCLUSIONS The 24 / 4 ULDOCP regimen seems to be a safe and effective contraceptive method for use in rural population after properly counselling them. The reduced pill free interval of 4 days offered additional advantages. KEYWORDS Ultra-Low Dose Oral Contraceptive Pills (ULDOCP), Ethinyl Estradiol (EE), Safe Contraception, Gestodene, BTB (Break Through Bleeding)

Objectives The current study aimed to design an ultra-low-dose CT examination protocol using a deep learning approach suitable for clinical diagnosis of COVID-19 patients. Methods In this study, 800, 170, and 171 pairs of ultra-low-dose and full-dose CT images were used as input/output as training, test, and external validation set, respectively, to implement the full-dose prediction technique. A residual convolutional neural network was applied to generate full-dose from ultra-low-dose CT images. The quality of predicted CT images was assessed using root mean square error (RMSE), structural similarity index (SSIM), and peak signal-to-noise ratio (PSNR). Scores ranging from 1 to 5 were assigned reflecting subjective assessment of image quality and related COVID-19 features, including ground glass opacities (GGO), crazy paving (CP), consolidation (CS), nodular infiltrates (NI), bronchovascular thickening (BVT), and pleural effusion (PE). Results The radiation dose in terms of CT dose index (CTDIvol) was reduced by up to 89%. The RMSE decreased from 0.16 ± 0.05 to 0.09 ± 0.02 and from 0.16 ± 0.06 to 0.08 ± 0.02 for the predicted compared with ultra-low-dose CT images in the test and external validation set, respectively. The overall scoring assigned by radiologists showed an acceptance rate of 4.72 ± 0.57 out of 5 for reference full-dose CT images, while ultra-low-dose CT images rated 2.78 ± 0.9. The predicted CT images using the deep learning algorithm achieved a score of 4.42 ± 0.8. Conclusions The results demonstrated that the deep learning algorithm is capable of predicting standard full-dose CT images with acceptable quality for the clinical diagnosis of COVID-19 positive patients with substantial radiation dose reduction. Key Points • Ultra-low-dose CT imaging of COVID-19 patients would result in the loss of critical information about lesion types, which could potentially affect clinical diagnosis. • Deep learning–based prediction of full-dose from ultra-low-dose CT images for the diagnosis of COVID-19 could reduce the radiation dose by up to 89%. • Deep learning algorithms failed to recover the correct lesion structure/density for a number of patients considered outliers, and as such, further research and development is warranted to address these limitations.

Цель. Оценить возможности разработанного метода автоматического определения плотности печени по данным нативны хультранизкодозных и стандартных компьютерных томограмм органов грудной клетки, при которых в область сканирования попадает верхний этаж брюшной полости. Материал и методы. Проведен ретроспективный анализ данных 10000 пациентов, которым была выполнена ультранизкодозная компьютерная томография. Из них отобраны 100 пациентов, дополнительно прошедших стандартную компьютерную томографию. Средний возраст пациентов: 62,5±12 лет (M±σ). Ручное измерение плотности печени проводилось во II, IV, VII-VIII сегментах. Дополнительно измерялась плотность селезенки. Стеатоз печени считался достоверным при плотности печени

OBJECTIVE. The objective of our study was to assess the effect of the combination of deep learning-based denoising (DLD) and iterative reconstruction (IR) on image quality and Lung Imaging Reporting and Data System (Lung-RADS) evaluation on chest ultra-low-dose CT (ULDCT). MATERIALS AND METHODS. Forty-one patients with 252 nodules were evaluated retrospectively. All patients underwent ULDCT (mean ± SD, 0.19 ± 0.01 mSv) and standard-dose CT (SDCT) (6.46 ± 2.28 mSv). ULDCT images were reconstructed using hybrid iterative reconstruction (HIR) and model-based iterative reconstruction (MBIR), and they were postprocessed using DLD (i.e., HIR-DLD and MBIR-DLD). SDCT images were reconstructed using filtered back projection. Three independent radiologists subjectively evaluated HIR, HIR-DLD, MBIR, and MBIR-DLD images on a 5-point scale in terms of noise, streak artifact, nodule edge, clarity of small vessels, homogeneity of the normal lung parenchyma, and overall image quality. Two radiologists independently evaluated the nodules according to Lung-RADS using HIR, MBIR, HIR-DLD, and MBIR-DLD ULDCT images and SDCT images. The median scores for subjective analysis were analyzed using Wilcoxon signed rank test with Bonferroni correction. Intraobserver agreement for Lung-RADS category between ULDCT and SDCT was evaluated using the weighted kappa coefficient. RESULTS. In the subjective analysis, ULDCT with DLD showed significantly better scores than did ULDCT without DLD (p < 0.001), and MBIR-DLD showed the best scores among the ULDCT images (p < 0.001) for all items. In the Lung-RADS evaluation, HIR showed fair or moderate agreement (reader 1 and reader 2: κw = 0.46 and 0.32, respectively); MBIR, moderate or good agreement (κw = 0.68 and 0.57); HIR-DLD, moderate agreement (κw = 0.53 and 0.48); and MBIR-DLD, good agreement (κw = 0.70 and 0.72). CONCLUSION. DLD improved the image quality of both HIR and MBIR on ULDCT. MBIR-DLD was superior to HIR_DLD for image quality and for Lung-RADS evaluation.

Aims In image-guided radiotherapy, daily cone-beam computed tomography (CBCT) is rarely applied to children due to concerns over imaging dose. Simulating low-dose CBCT can aid clinical protocol design by allowing visualisation of new scan protocols in patients without delivering additional dose. This work simulated ultra-low-dose CBCT and evaluated its use for paediatric image-guided radiotherapy by assessment of image registration accuracy and visual image quality. Materials and methods Ultra-low-dose CBCT was simulated by adding the appropriate amount of noise to projection images prior to reconstruction. This simulation was validated in phantoms before application to paediatric patient data. Scans from 20 patients acquired at our current clinical protocol (0.8 mGy) were simulated for a range of ultra-low doses (0.5, 0.4, 0.2 and 0.125 mGy) creating 100 scans in total. Automatic registration accuracy was assessed in all 100 scans. Inter-observer registration variation was next assessed for a subset of 40 scans (five scans at each simulated dose and 20 scans at the current clinical protocol). This subset was assessed for visual image quality by Likert scale grading of registration performance and visibility of target coverage, organs at risk, soft-tissue structures and bony anatomy. Results Simulated and acquired phantom scans were in excellent agreement. For patient scans, bony atomy registration discrepancies for ultra-low-dose scans fell within 2 mm (translation) and 1° (rotation) compared with the current clinical protocol, with excellent inter-observer agreement. Soft-tissue registration showed large discrepancies. Bone visualisation and registration performance reached over 75% acceptability (rated ‘well’ or ‘very well’) down to the lowest doses. Soft-tissue visualisation did not reach this threshold for any dose. Conclusion Ultra-low-dose CBCT was accurately simulated and evaluated in patient data. Patient scans simulated down to 0.125 mGy were appropriate for bony anatomy set-up. The large dose reduction could allow for more frequent (e.g. daily) image guidance and, hence, more accurate set-up for paediatric radiotherapy.

Introduction: Atrophic vaginitis is a common problem in postmenopausal women and results from decreased levels of blood estrogen. It is associated with symptoms of itching, burning, dyspareunia, and postmenopausal bleeding. The present study evaluated the effects of fenugreek extract on atrophic vaginitis. Materials and Methods: This randomized controlled clinical trial was performed on 60 postmenopausal women in Ardabil, Iran, in 2018. The participants were selected using block randomization with the allocation ratio 1:1. Those in the intervention group received 0.5g (the applicator filled to the half-full mark) fenugreek vaginal cream 5% twice a week for 12 weeks. The control group received conjugated estrogens vaginal cream at the dose of 0.625 mg (the applicator filled to the half-full mark) containing 0.3 mg of conjugated estrogens. Atrophic vaginitis was evaluated before and after the treatment through clinical examination, clinical signs, and measurement of Vaginal Maturation Index (VMI). Findings: After the 12-week intervention and modification of the baseline score, the mean (standard error) score for atrophic vaginitis signs was 3.100 (1.43-4.75). This difference was statistically significant in intragroup comparison and in favor of the control group in intergroup comparison (p=0.001). VMI was less than 49% in 86.7% and 46.7% of the participants in the intervention and control groups, respectively. This was a significant difference in favor of the control group (p=0.001). Conclusion: The results of this study showed that total fenugreek extract could be effective in treating signs of atrophic vaginitis, but it was not as effective as ultra-low-dose estrogen.

OBJECTIVE The aim of this study was to compare three different reconstruction algorithms for the volumetry of the visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) on ultra-low-dose computed tomography (CT) images. METHODS Thirty-seven male patients underwent ultra-low-dose CT at the level of the fourth lumbar vertebra (22.5 mm in z-axis). The acquisitions were reconstructed in 5-mm slices with 50% overlap using filtered back projection (FBP), hybrid iterative reconstruction (HIR), and iterative model-based reconstruction (IMR) techniques. The volume of VAT and SAT was measured using an interactive seed-growing segmentation and by thresholding (-30 to -190 HU). RESULTS The volume of SAT measured by the interactive method was smaller in FBP compared with both HIR (P = 0.0011) and IMR (P = 0.0034), and the volume of VAT was greater in IMR compared with HIR (P = 0.0253) or FBP (P = 0.0065). Using the thresholding method, IMR volumes of VAT were greater compared with HIR (P

Objectives The current study aimed to evaluate different CBCT exposure protocols and influencing factors affecting the subjective image quality of scans taken for endodontic indications. Materials and methods Twelve extracted teeth, comprising of two sets of maxillary molars, premolars, canines and incisors, mandibular premolars, and molars, were endodontically treated, and either received a fiber or metal post. The teeth were scanned by CBCT imaging before and after root canal treatment, and after post insertion. Each scan was performed thrice, using an ultra low dose (ULD), standard (SM), and high-resolution mode (HR), respectively. Twelve observers—4 endodontists, 4 periodontists, and 4 radiologists—assessed the subjective image quality using visual analogue scales (VAS). Potential influencing factors were evaluated including acquisition mode, observer specialty, stage of treatment, type of post, and type of tooth, using one-way ANOVA and T test. Results Teeth scanned with the ULD had the highest average VAS score (72.5), followed by HR (70.2), and SM (69.0) for values pooled from all teeth and observers. CBCT acquisition mode was not a significant influencing factor on the VAS scores. Observer specialty, stage of treatment, type of post, and type of tooth were significant influencing factors. Conclusions Based on the present in vitro data, a low-dose CBCT mode seems not to negatively affect the perception of image quality. Clinical relevance The findings from this in vitro study demonstrate that a low-dose CBCT mode might have potential for diagnostics prior to or following endodontic treatment.

Background Localized pleural adhesion (LPA) evaluation in the apical region is difficult even with four-dimensional ultra-low-dose computed tomography (4D-ULDCT) in the supine position due to smaller pleural movements. Purpose To assess usability of 4D-ULDCT in the lateral decubitus (LD) position for LPA detection in the apical region. Material and Methods Forty-seven patients underwent 4D-ULDCT of a single respiration cycle with 16-cm coverage of body axis in supine and LD positions with the affected lung uppermost. Intraoperative thoracoscopic findings confirmed LPA presence. A pleural point and a corresponding point on costal outer edge were placed in identical axial planes at end-inspiration. Pleuro-chest wall distance between two points (PCD) was calculated at each respiratory phase. In the affected lung, average change in amount of PCD (PCDACA) was compared between patients with and without LPA in total and two sub-groups (non-COPD and COPD, non-emphysematous and emphysematous patients) in supine and non-dependent (ND) LD positions. Receiver operating characteristic (ROC) curve analysis was performed to determine optimal thresholds in PCDACA for differentiating patients with LPA from those without. Results In COPD/emphysematous patients and total population, PCDACA with LPA was smaller than in those without in the supine and NDLD positions for overall, lateral, and dorsal regions. For the lateral region in COPD patients, area under ROC curve (AUC) increased from supine (0.64) to NDLD position (0.81). For the dorsal region in emphysematous patients, AUC increased from supine (0.76) to NDLD position (0.96). Conclusion 4D-ULDCT in LD position may be useful for LPA detection in apical regions for COPD and/or emphysematous patients.

Cadmium-Zinc-Telluride (CZT) technology allows use of low activities of radiopharmaceuticals. The aim was to verify the values of left ventricular volume parameters, obtained via ultra-low-dose thallium Single Photon Emission Computed Tomography (SPECT) using a CZT camera. Forty-five patients referred for an assessment of myocardial perfusion or viability imaging were examined using CZT-SPECT and 1.5 T magnetic resonance (MRI) scanner. The ultra-low-dose protocol with 0.5 Mbq 201-Tl per kg of body weight was used. The values of end-systolic (ESV) and end-diastolic volumes (EDV), left ventricular ejection fraction (EF) and myocardial mass (MM) were assessed using both techniques. A very good correlation was found between the EF, ESV, and EDV values assessed with CZT-SPECT and cardiac magnetic resonance MRI; the Pearson coefficients were 0.86, 0.95, and 0.91, respectively. A moderate correlation was found for myocardial mass, r = 0.57. Compared to MRI, SPECT systematically overestimated ESV and MM, while it underestimates the EF, with P ≤ .001 in all cases. There was no difference in EDV estimation. Left ventricular volumes and ejection fraction assessed via ultra-low-dose CZT-SPECT showed very good correlation with the values obtained by MRI. A moderate correlation was found for myocardial mass.

In females, endogenous estrogen secretion increases gradually before pubertal development. The benefits of low-dose estrogen therapy in patients with Turner syndrome were originally discussed by Ross et al. and Quigley et al. These seminal studies used ethinyl estradiol (EE2), starting at a dose of 25 ng/kg/d. We hypothesized that the initial dosage of estrogen could be titrated to more closely mimic physiological increments of endogenous estrogen. Therefore, our recent study initiated EE2 treatment at a dosage of 1–2 ng/kg/d, an ultra-low-dose estrogen therapy in pediatric patients with Turner syndrome. The ultra-low-dose estrogen therapy in this syndrome produced a good final height outcome but achieved suboptimal bone mineral density (BMD). In the present review, we have explained our findings to clarify the merits and demerits of this new therapy and to promote further discussion and research. This type of ultra-low-dose estrogen therapy, initiated at an early age, could be ideal for estrogen replacement in female patients with hypogonadism, such as Turner syndrome.

Objectives To analyze differences in variation of orthodontic diagnostic measurements on lateral cephalograms reconstructed from ultra low dose-low dose (ULD-LD) cone beam computed tomography (CBCT) scans (RLC) as compared to variation of measurements on standard lateral cephalograms (SLC), and to determine if it is justifiable to replace a traditional orthodontic image set for an ULD-LD CBCT with a reconstructed lateral cephalogram. Material and methods ULD-LD CBCT images and SLCs were made of forty-three dry human skulls. From the ULD-LD CBCT dataset, a lateral cephalogram was reconstructed (RLC). Cephalometric landmarks (13 skeletal and 7 dental) were identified on both SLC and RLC twice in two sessions by two calibrated observers. Thirteen cephalometric variables were calculated. Variations of measurements, expressed as standard deviations of the 4 measurements on SLC and RLC, were analyzed using a paired sample t-test. Differences in the number of observations deviating ≥ 2.0 mm or degrees from the grand mean between SLC and RLC were analyzed using a McNemar test. Results Mean SDs for 7 out of 13 variables were significantly smaller for SLCs than those for RLCs, but differences were small. For 9 out of 13 variables, there was no significant difference between SLC and RLC for the number of measurements outside the range of 2 mm or degrees. Conclusions Based on the lower radiation dose and the small differences in variation in cephalometric measurements on reconstructed LC compared to standard dose LC, ULD-LD CBCT with reconstructed LC should be considered for orthodontic diagnostic purposes. Clinical relevance ULD-LD CBCT with reconstructed LC should be considered for orthodontic purposes.

In recent years, long-distance subsea tiebacks have become a preferred field development option for deep and ultra-deepwater production. However, conditions such as lengthy umbilical systems, high pressures and variable temperatures conditions pose challenges for the continuous injection of various flow assurance chemicals. Severe operating conditions often require relatively high volumes of diluted inhibitors to be stored and injected offshore, resulting in high CAPEX costs for the installation of large topsides chemical storage tanks and their associated weight increases. Alliance Engineering estimates a deepwater platform's topsides installed costs are within the range of $35,000-$50,000/ton. It is possible to achieve significant capital cost savings on new platform designs if the dosage rates and subsequently offshore storage volumes of the highest usage production chemicals such as asphaltene inhibitors could be significantly reduced. This paper presents information on a new class of biosurfactants that are bio-based and eco-acceptable with potentials for development of ultra-low dose asphaltene inhibitors for offshore applications. Asphaltenes were extracted from chemical free crude oil samples and a curve of solubility with different ratios of heptane was obtained for each sample in order to determine the best conditions to perform the screening tests. A new class of glycolipid biosurfactants (GLP-U) was developed as an asphaltene dispersants effective at low concentrations for use in offshore applications. The new GLP-U biosurfactants are eco-acceptable and soluble in the organic solvents commonly used in offshore production chemicals. GLP-U were proved to be effective in dispersing and preventing precipitation of isolated asphaltenes at dosage rates as low as 25 mg/L (active substance), while for comparison a dodecylbenzesulfonic acid-based inhibitor provided inhibition at significantly higher concentrations (at least 40 times more).

Background Chest CT screening improves lung cancer detection at early stages for high-risk populations, such as heavy-smokers. However, CT screening also has some considerable disadvantages as radiation exposure, patient distress and overdiagnosis. Tobacco is also a major risk factor for coronary heart disease. Purpose To assess whether an additional chest ultra-low-dose CT scan to the coronary CT angiography protocol can be used for lung cancer screening among patients with suspected coronary artery disease. Methods 980 patients underwent coronary CT angiography for assessment of coronary artery disease, additionally undergoing ultra-low-dose CT screening to early diagnosis of lung cancer in the same scanner (80kVp and 15mAs). Patients presenting pulmonary nodules were followed-up for two years, repeating low-dose CTs in intervals of 3, 6, or 12 months based on nodule size and growth rate in accordance with National Comprehensive Cancer Network guidelines. Results Ultra-low-dose CT identified 437 patients with solitary pulmonary nodules (45%), with a mean diameter of 5.40±4.10mm. One hundred fifty two were >6mm, and in 83% (n=126) of these cases they were false positive findings, further confirmed by follow-up (n=114), resection (n=3), or biopsy (n=9). Lung cancer was detected in twenty nine patients due to CT screening (diagnostic yield: 2.9%). Among these, 20 cases could not be detected in the cardiac field of view. Most patients were in early stages of the disease, and eight patients diagnosed at advanced stages (IIIB and IV). The addition of the ultra-low-dose CT scan represented a radiation dose increment of 1.32±0.29% (effective dose, 0.12±0.04mSv). Conclusions Lung cancer might be detected using additional ultra-low-dose protocols in coronary CT angiography scans among patients with suspected coronary artery disease. Funding Acknowledgement Type of funding sources: None.

Rituximab is a monoclonal antibody which binds to the CD-20 antigen expressed on B-cell lymphocytes (1). It has shown efficacy in the treatment of pemphigus by depleting the B-cells to which it binds reducing production of destructive antibodies (2, 3).

Background: Pemphigus vulgaris is an autoimmune blistering disease affecting the skin and mucous membranes. Current treatments for pemphigus vulgaris include anti-inflammatory and immunosuppressive...

Background and Purpose: Classically, abdominal X-ray (KUB), ultrasound, or a combination of both have been routinely used for ureteral stone surveillance after initial diagnosis. More recently, ult...

Purpose: To describe the outcome of ultra-low-dose (boom-boom) radiotherapy for choroidal lymphoma. Methods: Retrospective series of three consecutive patients with biopsy-proven choroidal lymphoma treated with ultra-low-dose radiotherapy. Results: The three patients (two male, one female) of mean age 70 years (range, 64–74 years) demonstrated presenting visual acuity in the affected eye between 20/40 and 20/50. The choroidal lymphoma was unilateral in all cases and presented with multifocal yellow patchy choroidal infiltration, located in all four quadrants and measuring mean 2.9 mm (range, 1.9–4.0 mm) in thickness by ultrasonography. Anterior epibulbar extension of 5 mm diameter was noted in one case. By enhanced depth imaging optical coherence tomography, the choroidal infiltration demonstrated classic undulating appearance (n = 3), with subretinal fluid (n = 2) and intraretinal edema (n = 1). There was no systemic lymphoma in any case. Biopsy was performed in all three cases and was diagnostic (n = 1) or suggestive (n = 2) of B-cell lymphoma. Management involved ultra-low-dose radiotherapy (4 Gy delivered in two fractions, “boom-boom”). On follow-up (mean = 14 months, range = 6–24 months), complete tumor regression on ophthalmoscopy was documented in all three cases, with enhanced depth imaging optical coherence tomography and ultrasonography demonstrating evidence of lymphoma resolution and visual acuity improvement to 20/25–20/40. There were no radiation complications. Conclusion: In this small case series, ultra-low-dose (boom-boom) radiotherapy was effective for choroidal lymphoma with favorable response and minimal side effects.

Purpose The aim of this study was to demonstrate that a low helical pitch causes increased photon starvation artifacts at ultra-low-dose CT. Methods A cylindrical water phantom with a diameter of 30 cm was scanned on two different generation CT scanners: a 64-slice scanner (Sensation 64, Siemens Healthcare) and a 192-slice scanner (Somatom Force, Siemens Healthcare) at multiple effective mAs levels (mAs/pitch = 200, 100, 50, 25, and 12). The corresponding CTDIvol values were 4.1, 2.0, 1.0, 0.5 mGy, on the 64-slice scanner and 3.8, 1.9, 1.0, 0.5 mGy on the 192-slice scanner, for the selected effective mAs values. For each dose setting, the scan was repeated at four helical pitches: 1.2, 0.9, 0.6, and the lowest achievable pitch on each scanner. The tube current was automatically adjusted by the scanner so that the effective mAs, and thus CTDIvol , were kept the same for different pitches. All CT data sets were reconstructed with a slice thickness of 3mm and a medium smooth kernel. Images acquired at the same dose level but different helical pitches were visually inspected to assess photon starvation artifacts and noise levels. Results At the same radiation dose, image noise increased with the decreasing helical pitch. The increase was more severe on the old-generation 64-slice scanner. Photon starvation artifacts were evident at 200 effective mAs on the 64-slice scanner at 80 kV. On the 192-slice scanner there was no visible photon starvation artifacts at both 200 and 50 effective mAs (CTDIvol = 4.1 mGy and 1.0 mGy, respectively); nor was there a visible impact from the lower helical pitch. Only when the dose was lowered to be extremely low (~0.26 mGy, achievable at 70 kV), did photon starvation artifacts become evident. Conclusions A low helical pitch may increase image noise and photon starvation artifacts compared to a higher pitch for the same dose level, particularly at ultra-low dose CT.

Objective To investigate the treatment efficacy of ultra-low-dose bevacizumab for cerebral radiation necrosis. Methods Patients with cerebral radiation necrosis after stereotactic radiotherapy (SRT) confirmed by imaging were included. Bevacizumab (1 mg/kg, once every three weeks, for at least three continuous treatments) was administered. The primary endpoints included change in cerebral necrosis symptoms, volume of intracranial edema, and changes in MRI signals. The secondary endpoints were adverse reactions of bevacizumab treatment. Results In total, 21 patients were included in this study, all of whom received SRT between December 2016 and February 2019, developed cerebral radiation necrosis, and were treated with bevacizumab. Twenty patients were symptomatic from radiation necrosis, and the symptoms were alleviated in 18 patients (90%). Twenty patients had intracranial edema, and the grade of edema index (EI) was improved in 19 patients (95%). The intensity of the intracranial-enhanced MRI signals was significantly reduced in 20 patients (95.24%). The adverse reactions of bevacizumab treatment were mild, and no adverse reactions more severe than grade 2 were found. Conclusion The preliminary results showed that ultra-low-dose bevacizumab had high efficacy for treating cerebral radiation necrosis, and could be a valid alternative to the standard-dose bevacizumab. Clinical registry Chinese clinical trial registry (ChiCTR-IOD-16009803).

PURPOSE Reducing dose level to achieve ALARA is an important task in diagnostic and therapeutic applications of computed tomography (CT) imaging. Effective image quality enhancement strategies are crucial to compensate for the degradation caused by dose reduction. In the past few years, deep learning approaches have demonstrated promising denoising performance on natural/synthetic images. This study tailors a neural network model for (ultra-)low-dose CT denoising, and assesses its performance in enhancing CT image quality and emphysema quantification. METHODS The noise statistics in low-dose CT images has its unique characteristics and differs from that used in general denoising models. In this study, we first simulate the paired ultra-low-dose and targeted high-quality image of reference, with a well-validated pipeline. These paired images are used to train a denoising convolutional neural network (DnCNN) with residual mapping. The performance of the DnCNN tailored to CT denoising (DnCNN-CT) is assessed over various dose reduction levels, with respect to both image quality and emphysema scoring quantification. The possible over-smoothing behavior of DnCNN and its impact on different subcohort of patients are also investigated. RESULTS Performance evaluation results showed that DnCNN-CT provided significant image quality enhancement, especially for very-low-dose level. With DnCNN-CT denoising on 3%-dose cases, the peak signal-to-noise ratio improved by 8 dB and the structure similarity index increased by 0.15. This outperformed the original DnCNN and the state-of-the-art nonlocal-mean-type denoising scheme. Emphysema mask was also investigated, where lung voxels of abnormally low attenuation coefficient were marked as potential emphysema. Emphysema mask generated after DnCNN-CT denoising on 3%-dose image was demonstrated to agree well with that from the full-dose reference. Despite over-smoothing in DnCNN denoising, which contributed to slight underestimation of emphysema score compared to the reference, such minor overcorrection did not affect clinical conclusions. The proposed method provided effective detection for cases with appreciable emphysema while serving as a reasonable correction for normal cases without emphysema. CONCLUSIONS This work provides a tailored DnCNN for (ultra-)low-dose CT denoising, and demonstrates significant improvement on both the image quality and the clinical emphysema quantification accuracy over various dose levels. The clinical conclusion of emphysema obtained from the denoised low-dose images agrees well with that from the full-dose ones.

This article reviews the neurocognitive advantages and drawbacks of cannabinoid substances, and discusses the possible physiological mechanisms that underlie their dual activity. The article further reviews the neurocognitive effects of ultra-low doses of ∆9-tetrahydrocannabinol (THC; 3-4 orders of magnitude lower than the conventional doses) in mice, and proposes such low doses of THC as a possible remedy for various brain injuries and for the treatment of age-related cognitive decline.

Atherosclerotic diseases are systemic and patient outcomes depend on comprehensive imaging evaluation. Computed tomography angiography (CTA) is a powerful tool used to assess atherosclerosis. However, the scanning protocol is designed for cardiovascular and cerebrovascular imaging, which require considerations into the radiation dose, contrast agent and image quality. The purpose of the present study was to evaluate ultra-low dose one-step CTA for coronary, carotid and cerebral arteries with a low concentration contrast agent. A total of 78 patients were enrolled and randomly divided into two groups: Group A (n=38) and B (n=40). High-pitch CTA for coronary, carotid and cerebral arteries with a tube voltage of 70 or 80 kVp and 40 ml contrast agent (270 mgI/ml) was performed by a 128-slice dual-source CT scanner for group A. Standard high-pitch CTA with a tube voltage of 100 kVp and 60 ml contrast agent (370 mgI/ml) was conducted for group B. The image quality, radiation dose and amount of contrast agent in group A were evaluated and compared with group B. The dose length product for groups A and B was 62.95±21.54 vs. 160.15±15.13 mGy cm, respectively (t=-23.157, P

Alzheimer’s disease (AD) is the most common form of dementia. AD has a physical, emotional, and economic impact on the patients and their families and society at large. More than a decade since its discovery, there is still no available treatment. Δ9-tetrahydrocannabinol (THC) is emerging as a promising therapeutic agent. Using THC in conventional-high doses may have deleterious effects. Therefore, we propose to use an ultra-low dose of THC (ULD-THC). We previously published that a single injection of ULD-THC elevated Sirtuin-1 (Sirt-1) levels in the brain and ameliorated cognitive functioning in several models of brain injuries as well as in naturally aging mice. Our working hypothesis suggests that ULD-THC can prevent and even reverse AD pathology. In this preliminary study, we saw that a single injection of ULD-THC alleviated cognitive impairments of a mice model for AD, 5xFAD mice. Our work may establish the foundations for the development of a pharmaceutical preparation for the treatment of AD patients, thus, bringing the ULD-THC treatment closer to clinical application.

BACKGROUND/AIM Investigation of the influence of different ultra-low dose computed tomography (ULDCT) protocols on the detection of solid and subsolid nodules in a phantom study. PATIENTS AND METHODS A chest phantom with pulmonary nodules was scanned with different CT protocols ranging from ultra-low dose settings with spectral shaping to a standard low dose lung cancer screening protocol. Image analysis was performed with different reconstruction algorithms and dedicated computer aided detection (CAD), which was compared to manual readout. RESULTS The highest sensitivity rates (83%) were achieved for the 90 mAs and 120 mAs protocols when reconstructed with ADMIRE 3 or 5 and manual readout. The only statistically significant difference was found for subsolid nodules with preference of manual readout compared to CAD (p

International audience; Background: Ultra low dose chest computed tomography (CT) acquisitions have been used for selected emergency room patients with acute dyspnea or minor thoracic trauma. The purpose of this study was to evaluate the diagnostic performance of ultra-low-dose (ULD) chest CT for detecting viral pneumonia patterns compared to standard (STD) dose chest CT.Methods: All consecutive adult patients with two non-enhanced chest CT acquisitions, one STD and one ULD, for suspicion of viral pneumonia between March 5th and April 2nd 2020 were included. CT results were divided into two groups: non-viral pneumonia CT or compatible with viral pneumonia CT based on viral pneumonia CT patterns: ground-glass opacity (GGO), consolidation, crazy paving, air bronchogram signs and fibrous stripes. The diagnostic performance of ULD CT for suspicion of viral pneumonia was evaluated. For CTs compatible with viral pneumonia, CT pattern detection on ULD CT was assessed and STD CT was used as a reference.Results: The study included 380 patients with 97 CTs (25.5%) compatible with viral pneumonia. The mean effective doses (EDs) were 1.66 (1.29; 2.18) mSv for STD and 0.20 (0.18; 0.22) mSv for ULD CT (P

BACKGROUND: The weightings of iterative reconstruction algorithm can affect CT radiomic quantification. But, the effect of ASiR-V levels on the reproducibility of CT radiomic features between ultra-low-dose computed tomography (ULDCT) and low-dose computed tomography (LDCT) is still unknown. The purpose of study is to investigate whether adaptive statistical iterative reconstruction-V (ASiR-V) levels affect radiomic feature quantification using ULDCT and to assess the reproducibility of radiomic features between ULDCT and LDCT. METHODS: Sixty-three patients with pulmonary nodules underwent LDCT (0.70±0.16 mSv) and ULDCT (0.15±0.02 mSv). LDCT was reconstructed with ASiR-V 50%, and ULDCT with ASiR-V 50%, 70%, and 90%. Radiomics analysis was applied, and 107 features were extracted. The concordance correlation coefficient (CCC) was calculated to describe agreement among ULDCTs and between ULDCT and LDCT for each feature. The proportion of features with CCC >0.9 among ULDCTs and between ULDCT and LDCT, and the mean CCC for all features between ULDCT and LDCT were also compared. RESULTS: Sixty-three solid nodules (SNs) and 48 pure ground-glass nodules (pGGNs) were analyzed. There was no difference for the proportion of features in SNs among ULDCTs and between ULDCT and LDCT (P>0.05). The proportion of features in pGGNs were highest for ULDCT(70%) (vs.) (90%) (78.5%) and ULDCT(90%) vs. LDCT(50%) (50.5%). In SNs, the mean CCC for ULDCT(90%) vs. LDCT(50%) was 0.67±0.26, not different with that for ULDCT(50%) vs. LDCT(50%) (0.68±0.24) and ULDCT(70%) vs. LDCT(50%) (0.64±0.21) (P>0.05). In pGGNs, the mean CCC for ULDCT(90%) vs. LDCT(50%) was 0.79±0.19, higher than that for ULDCT(50%) vs. LDCT(50%) (0.61±0.28) and ULDCT(70%) vs. LDCT(50%) (0.76±0.24) (P

Local minimally invasive injection of anticancer therapies is a compelling approach to maximize the utilization of drugs and reduce the systemic adverse drug effects. However, the clinical translation is still hampered by many challenges such as short residence time of therapeutic agents and the difficulty in achieving multi-modulation combination therapy. Herein, mesoporous silica-coated gold nanorods (AuNR@SiO2 ) core-shell nanoparticles are fabricated to facilitate drug loading while rendering them photothermally responsive. Subsequently, AuNR@SiO2 is anchored into a monodisperse photocrosslinkable gelatin (GelMA) microgel through one-step microfluidic technology. Chemotherapeutic drug doxorubicin (DOX) is loaded into AuNR@SiO2 and 5,6-dimethylxanthenone-4-acetic acid (DMXAA) is loaded in the microgel layer. The osteosarcoma targeting ligand alendronate is conjugated to AuNR@SiO2 to improve the tumor targeting. The microgel greatly improves the injectability since they can be dispersed in buffer and the injectability and degradability are adjustable by microfluidics during the fabrication. The drug release can, in turn, be modulated by multi-round light-trigger. Importantly, a single super low drug dose (1 mg kg-1 DOX with 5 mg kg-1 DMXAA) with peritumoral injection generates long-term therapeutic effect and significantly inhibited tumor growth in osteosarcoma bearing mice. Therefore, this nanocomposite@microgel system can act as a peritumoral reservoir for long-term effective osteosarcoma treatment.

Background While the second wave of COVID-19 pandemic almost reached its climax, unfortunately, new viral strains are rapidly spreading, and numbers of infected young adults are rising. Consequently, chest high-resolution computed tomography (HRCT) demands are increasing, regarding patients’ screening, initial evaluation and follow up. This study aims to evaluate the detection accuracy of ultra-low-dose chest CT in comparison with the routine low-dose chest CT to reduce the irradiation exposure hazards. Results This study was prospectively conducted on 250 patients during the period from 15th December 2020 to 10th February 2021. All of the included patients were clinically suspected of COVID-19 infection. All patients were subjected to routine low-dose (45 mAs) and ultra-low-dose (22 mAs) chest CT examinations. Finally, all patients had confirmatory PCR swab tests and other dedicated laboratory tests. They included 149 males and 101 females (59.6%:40.4%). Their age ranged from 16 to 84 years (mean age 50 ± 34 SD). Patients were divided according to body weight; 104 patients were less than 80 kg, and 146 patients were more than 80 kg. HRCT findings were examined by two expert consultant radiologists independently, and data analysis was performed by other two expert specialist and consultant radiologists. The inter-observer agreement (IOA) was excellent (96–100%). The ultra-low-dose chest CT reached 93.53–96.84% sensitivity and 90.38–93.84% accuracy. The signal-to-noise ratio (SNR) is 12.8:16.1; CTDIvol (mGy) = 1.1 ± 0.3, DLP (mGy cm) = 42.2 ± 7.9, mean effective dose (mSv/mGy cm) = 0.59 and absolute cancer risk = 0.02 × 10-4. Conclusion Ultra-low-dose HRCT can be reliably used during the second wave of COVID-19 pandemic to reduce the irradiation exposure hazards.

Background This study examined whether ultra-low-dose chest computed tomography (ULD-CT) could improve detection of acute chest conditions. Purpose To determine (i) whether diagnostic accuracy of ULD-CT is superior to supine chest X-ray (sCXR) for acute chest conditions and (ii) the feasibility of ULD-CT in an emergency department. Material and Methods From 1 February to 31 July 2019, 91 non-traumatic patients from the Emergency Department were prospectively enrolled in the study if they received an sCXR. An ULD-CT and a non-contrast chest CT (NCCT) scan were then performed. Three radiologists assessed the sCXR and ULD-CT examinations for cardiogenic pulmonary edema, pneumonia, pneumothorax, and pleural effusion. Resources and effort were compared for sCXR and ULD-CT to evaluate feasibility. Diagnostic accuracy was calculated for sCXR and ULD-CT using NCCT as the reference standard. Results The mean effective dose of ULD-CT was 0.05±0.01 mSv. For pleural effusion and cardiogenic pulmonary edema, no difference in diagnostic accuracy between ULD-CT and sCXR was observed. For pneumonia and pneumothorax, sensitivities were 100% (95% confidence interval [CI] 69–100) and 50% (95% CI 7–93) for ULD-CT and 60% (95% CI 26–88) and 0% (95% CI 0–0) for sCXR, respectively. Median examination time was 10 min for ULD-CT vs. 5 min for sCXR ( PConclusion ULD-CT seems equal or better in detecting acute chest conditions compared to sCXR. However, ULD-CT examinations demand more effort and resources.

Purpose Phantom studies in CT emphysema quantification show that iterative reconstruction and deep learning-based noise reduction (DLNR) allow lower radiation dose. We compared emphysema quantification on ultra-low-dose CT (ULDCT) with and without noise reduction, to standard-dose CT (SDCT) in chronic obstructive pulmonary disease (COPD). Method Forty-nine COPD patients underwent ULDCT (third generation dual-source CT; 70ref-mAs, Sn-filter 100kVp; median CTDIvol 0.38 mGy) and SDCT (64-multidetector CT; 40mAs, 120kVp; CTDIvol 3.04 mGy). Scans were reconstructed with filtered backprojection (FBP) and soft kernel. For ULDCT, we also applied advanced modelled iterative reconstruction (ADMIRE), levels 1/3/5, and DLNR, levels 1/3/5/9. Emphysema was quantified as Low Attenuation Value percentage (LAV%, ≤-950HU). ULDCT measures were compared to SDCT as reference standard. Results For ULDCT, the median radiation dose was 84 % lower than for SDCT. Median extent of emphysema was 18.6 % for ULD-FBP and 15.4 % for SDCT (inter-quartile range: 11.8–28.4 % and 9.2 %–28.7 %, p = 0.002). Compared to SDCT, the range in limits of agreement of emphysema quantification as measure of variability was 14.4 for ULD-FBP, 11.0–13.1 for ULD-ADMIRE levels and 10.1–13.9 for ULD-DLNR levels. Optimal settings were ADMIRE 3 and DLNR 3, reducing variability of emphysema quantification by 24 % and 27 %, at slight underestimation of emphysema extent (−1.5 % and −2.9 %, respectively). Conclusions Ultra-low-dose CT in COPD patients allows dose reduction by 84 %. State-of-the-art noise reduction methods in ULDCT resulted in slight underestimation of emphysema compared to SDCT. Noise reduction methods (especially ADMIRE 3 and DLNR 3) reduced variability of emphysema quantification in ULDCT by up to 27 % compared to FBP.