Neonatal digital chest radiography- should we be using additional copper filtration?

OBJECTIVES: Copper filtration removes lower energy X-ray photons, which do not enhance image quality but would otherwise contribute to patient radiation dose. This study explores the use of additional copper filtration for neonatal mobile chest imaging. METHODS: A controlled factorial-designed experiment was used to determine the effect of independent variables on image quality and radiation dose. These variables included: copper filtration (0 Cu, 0.1 Cu and 0.2 Cu), exposure factors, source-to-image distance and image receptor position (direct / tray). Image quality was evaluated using absolute visual grading analysis (VGA) and contrast-to-noise ratio (CNR) and entrance surface dose (ESD) was derived using an ionising chamber within the central X-ray beam. RESULTS: VGA, CNR and ESD significantly reduced (p < 0.01) when using added copper filtration. For 0.1 Cu, the percentage reduction was much greater for ESD (60%) than for VGA (14%) and CNR (20%), respectively. When compared to the optimal combinations of parameters for incubator imaging using no copper filtration, an increase in kV and mAs when using 0.1-mm Cu resulted in better image quality at the same radiation dose (direct) or, equal image quality at reduced dose (in-tray). The use of 0.1-mm Cu for neonatal chest imaging with a corresponding increase in kV and mAs is therefore recommended. CONCLUSION: Using additional copper filtration significantly reduces radiation dose (at increased mAs) without a detrimental effect on image quality. ADVANCES IN KNOWLEDGE: This is the first study, using an anthropomorphic phantom, to explore the use of additional Cu for digital radiography neonatal chest imaging and therefore helps inform practice to standardise and optimise this imaging examination.

Cost benefit analysis of portable chest radiography through glass: Initial experience at a tertiary care centre during COVID-19 pandemic.

INTRODUCTION: Portable chest radiography through glass (TG-CXR) is a novel technique, particularly useful during the COVID-19 (Coronavirus disease 2019) pandemic. The purpose of this study was to understand the cost and benefit of adopting TG-CXR in quantifiable terms. METHODS: Portable or bedside radiographs are typically performed by a team of two technologists. The TG-CXR method has the benefit of allowing one technologist to stay outside of the patient room while operating the portable radiography machine, reducing PPE use, decreasing the frequency of radiography machine sanitization and decreasing technologists' exposures to potentially infectious patients. The cost of implementing this technique during the current COVID-19 pandemic was obtained from our department's operational database. The direct cost of routinely used PPE and sanitization materials and the cost of the time taken by the technologists to clean the machine was used to form a quantitative picture of the benefit associated with TG-CXR technique. RESULTS: Technologists were trained on the TG-CXR method during a 15 min shift change briefing. This translated to a one-time cost of $424.88 USD. There was an average reduction of portable radiography machine downtime of 4 min and 48 s per study. The benefit of adopting the TG-CXR technique was $9.87 USD per patient imaged. This will result in a projected net cost savings of $51,451.84 USD per annum. CONCLUSION: Adoption of the TG-CXR technique during the COVID-19 pandemic involved minimal one-time cost, but is projected to result in a net-benefit of over $51,000 USD per annum in our emergency department.

Dynamic Chest X-Ray Using a Flat-Panel Detector System: Technique and Applications.

Dynamic X-ray (DXR) is a functional imaging technique that uses sequential images obtained by a flat-panel detector (FPD). This article aims to describe the mechanism of DXR and the analysis methods used as well as review the clinical evidence for its use. DXR analyzes dynamic changes on the basis of X-ray translucency and can be used for analysis of diaphragmatic kinetics, ventilation, and lung perfusion. It offers many advantages such as a high temporal resolution and flexibility in body positioning. Many clinical studies have reported the feasibility of DXR and its characteristic findings in pulmonary diseases. DXR may serve as an alternative to pulmonary function tests in patients requiring contact inhibition, including patients with suspected or confirmed coronavirus disease 2019 or other infectious diseases. Thus, DXR has a great potential to play an important role in the clinical setting. Further investigations are needed to utilize DXR more effectively and to establish it as a valuable diagnostic tool.

Morphological patterns and distributions in portable chest radiographs of COVID-19-positive cases admitted to a tertiary care hospital: An early experience from Scandinavia.

INTRODUCTION: Chest radiographic (CXR) features, particularly portable CXR findings, of COVID-19 have not yet been systematically described, either as a baseline tool or as a follow-up method, despite the continuing global pandemic. There is a marked paucity of articles detailing the CXR findings vis-à-vis a multitude of articles dedicated to the CT features of COVID-19. The purpose of this article is to describe the morphological and distributional patterns of the lung opacities in CXR and to classify the spectrum of essential features on portable AP chest radiographs of PCR-positive COVID-19 patients admitted in a tertiary care hospital in Scandinavia. To our knowledge, this is the first article to describe the morphological and topographical features of CXRs in COVID-19-positive cases. METHODS: A retrospective analysis of twenty (20) RT-PCR-positive COVID-19 patients admitted to the hospital between 12.03.2020 to 10.04.2020 was done in this study. Morphology and distribution of the opacities were reviewed by two senior consultants and analysed for patterns. RESULTS: Most patients had ground-glass opacities (80-85%) and interspersed interstitial opacities (70-75%), often with a characteristic appearance. The opacities were mostly bilateral (80%) and distributed in the lower zones (and to some extent mid zones) and in the middle and peripheral regions, with a tendency to merge towards the hilar areas. There were high interobserver agreements among various parameters and no significant statistical difference between observer 1 and 2. CONCLUSION: Chest radiographics show characteristic patterns and distributions, which can be used as an adjunct in the diagnosis and follow-up of COVID-19 patients in specific clinical contexts.

CT scanning in blunt chest trauma: validation of decision instruments.

OBJECTIVE: to perform an external validation of two clinical decision instruments (DIs) - Chest CT-All and Chest CT-Major - in a cohort of patients with blunt chest trauma undergoing chest CT scanning at a trauma referral center, and determine if these DIs are safe options for selective ordering of chest CT scans in patients with blunt chest trauma admitted to emergency units. METHODS: cross-sectional study of patients with blunt chest trauma undergoing chest CT scanning over a period of 11 months. Chest CT reports were cross-checked with the patients' electronic medical record data. The sensitivity and specificity of both instruments were calculated. RESULTS: the study included 764 patients. The Chest CT-All DI showed 100% sensitivity for all injuries and specificity values of 33.6% for injuries of major clinical significance and 40.4% for any lesion. The Chest CT-Major DI had sensitivity of 100% for injuries of major clinical significance, which decreased to 98.6% for any lesions, and specificity values of 37.4% for injuries of major clinical significance and 44.6% for all lesions. CONCLUSION: both clinical DIs validated in this study showed adequate sensitivity to detect chest injuries on CT and can be safely used to forego chest CT evaluation in patients without any of the criteria that define each DI. Had the Chest CT-All and Chest CT-Major DIs been applied in this cohort, the number of CT scans performed would have decreased by 23.1% and 24.6%, respectively, resulting in cost reduction and avoiding unnecessary radiation exposure.

Machine-learning classification of texture features of portable chest X-ray accurately classifies COVID-19 lung infection.

BACKGROUND: The large volume and suboptimal image quality of portable chest X-rays (CXRs) as a result of the COVID-19 pandemic could post significant challenges for radiologists and frontline physicians. Deep-learning artificial intelligent (AI) methods have the potential to help improve diagnostic efficiency and accuracy for reading portable CXRs. PURPOSE: The study aimed at developing an AI imaging analysis tool to classify COVID-19 lung infection based on portable CXRs. MATERIALS AND METHODS: Public datasets of COVID-19 (N = 130), bacterial pneumonia (N = 145), non-COVID-19 viral pneumonia (N = 145), and normal (N = 138) CXRs were analyzed. Texture and morphological features were extracted. Five supervised machine-learning AI algorithms were used to classify COVID-19 from other conditions. Two-class and multi-class classification were performed. Statistical analysis was done using unpaired two-tailed t tests with unequal variance between groups. Performance of classification models used the receiver-operating characteristic (ROC) curve analysis. RESULTS: For the two-class classification, the accuracy, sensitivity and specificity were, respectively, 100%, 100%, and 100% for COVID-19 vs normal; 96.34%, 95.35% and 97.44% for COVID-19 vs bacterial pneumonia; and 97.56%, 97.44% and 97.67% for COVID-19 vs non-COVID-19 viral pneumonia. For the multi-class classification, the combined accuracy and AUC were 79.52% and 0.87, respectively. CONCLUSION: AI classification of texture and morphological features of portable CXRs accurately distinguishes COVID-19 lung infection in patients in multi-class datasets. Deep-learning methods have the potential to improve diagnostic efficiency and accuracy for portable CXRs.

Diagnostic accuracy of portable chest radiograph in mechanically ventilated patients when compared with autopsy findings.

PURPOSE: Evaluate diagnostic accuracy of portable chest radiograph in mechanically ventilated patients taking autopsy findings as the gold standard and the interobserver agreement among intensivists and radiologists. MATERIALS AND METHODS: Retrospective study of 422 patients over 22 years who died in the ICU, underwent an autopsy, and had at least one portable chest radiograph 72 h prior to death. Two intensivists and two radiologists independently read each chest radiograph. Sensitivity, specificity, positive and negative likelihood ratios were evaluated. Overall performance metrics accuracy between intensivists and radiologists were compared using a generalized estimating equation. Cohen's kappa coefficient was used to evaluate the interobserver agreement with the following values: <0.20:poor, 0.21-0.40:fair, 0.41-0.60:moderate, 0.61-0.80:good, 0.81-1.00:excellent. RESULTS: Overall sensitivity and specificity for pneumonia was 24% and 91% respectively. Overall sensitivity and specificity for ARDS was 68% and 74% respectively. Sensitivity for pneumonia was higher among radiologists (p < 0,05). Specificity for ADRS was higher among radiologists (p < 0,05). Good interobserver agreement among radiologists and poor correlation between intensivists was found. CONCLUSIONS: Chest radiographs has a moderate specificity for ARDS and a high specificity for pneumonia, with limited sensitivity in both entities. Interobserver agreement of portable chest radiograph in the mechanically ventilated patients is higher between radiologists than intensivists.

Technique, radiation safety and image quality for chest X-ray imaging through glass and in mobile settings during the COVID-19 pandemic.

The COVID-19 pandemic in 2020 has led to preparations within our hospital for an expected surge of patients. This included developing a technique to perform mobile chest X-ray imaging through glass, allowing the X-ray unit to remain outside of the patient's room, effectively reducing the cleaning time associated with disinfecting equipment. The technique also reduced the infection risk of radiographers. We assessed the attenuation of different types of glass in the hospital and the technique parameters required to account for the glass filtration and additional source to image distance (SID). Radiation measurements were undertaken in a simulated set-up to determine the appropriate position for staff inside and outside the room to ensure occupational doses were kept as low as reasonably achievable. Image quality was scored and technical parameter information collated. The alternative to imaging through glass is the standard portable chest X-ray within the room. The radiation safety requirements for this standard technique were also assessed. Image quality was found to be acceptable or borderline in 90% of the images taken through glass and the average patient dose was 0.02 millisieverts (mSv) per image. The majority (67%) of images were acquired at 110 kV, with an average 5.5 mAs and with SID ranging from 180 to 300 cm. With staff positioned at greater than 1 m from the patient and at more than 1 m laterally from the tube head outside the room to minimise scatter exposure, air kerma values did not exceed 0.5 microgray (µGy) per image. This method has been implemented successfully.

Pre- and Post treatment Chest CT Changes in a patient with COVID-19 / Cambios de TC de tórax antes y después del tratamiento en un paciente con COVID-19

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Use of a portable computed tomography scanner for chest imaging of COVID-19 patients in the urgent care at a tertiary cancer center.

To present a novel use of a portable computed tomography (CT) for evaluation of COVID-19 patients presenting to an urgent care center (UCC). Infection control is imperative for hospitals treating patients with COVID-19, even more so in cancer centers, where the majority of the patient population is susceptible to adverse outcomes from the infection. Over the past several weeks, our department has worked to repurpose a portable CT scanner from our surgical colleagues that operates with fixed-parameters to perform non-contrast, helical, thin-slice chest imaging to address the known pulmonary complications of COVID-19. Despite the technical limitations of the portable CT unit that was repurposed for the UCC, diagnostic-quality images in an acute care setting were successfully obtained. Repurposing of a portable CT scanner for use in COVID-19 patients offers a feasible option to obtain diagnostic quality images while minimizing the risk of exposing other patients and hospital staff to an infected patient.

Axial or Helical? CT imaging of the thorax for dyspnoea patients with free-breathing using 16 cm wide-detector CT.

AIM: To compare image quality and radiation dose between fast-helical mode (FHM) and two-axial mode (TAM) in chest computed tomography (CT) with 16 cm wide-detector for emergency patients with dyspnoea. MATERIALS AND METHODS: Ninety-six emergency chest CT patients who cannot comply with breathing instructions were prospectively divided randomly into two groups: the FHM group (n=48, helical scan with 80 mm collimation and pitch 0.992:1), the TAM group (n=48, two axial scans with 160 mm collimation). Both groups used 0.28 seconds rotation speed and automatic tube current modulation. All scans were performed in free breathing. CT value, image noise, and signal-to-noise ratio (SNR) were measured on the descending thoracic aorta, lung parenchyma, and paraspinal muscle at the carina level. Two radiologists assessed images for subjective image quality, motion artefacts and diagnostic confidence. The volume CT dose index and dose-length product (DLP) were evaluated and effective dose (ED) was calculated. RESULTS: The TAM group required less exposure time than the FHM group (0.56 versus 1.14 seconds, p<0.001), reduced the frequency of motion artefacts caused by the diaphragm and heart by 50% and provided higher diagnostic confidence score (3.83 versus 3.58, p<0.05). TAM resulted in 24% lower DLP (96.76±31.58 versus 126.99±33.37 mGy·cm) and ED (1.36±0.44 versus 1.78±0.47 mSv) than FHM (p<0.001), but there was no difference in the CT value, image noise, and SNR between the two groups (p>0.05). CONCLUSIONS: TAM with 16 cm detector coverage further reduces the exposure time in chest CT for dyspnoea patients and ensures good image quality with 24% radiation dose reduction, compared with fast-helical chest CT with 80 mm collimation.

Effect of scan projection radiography coverage on tube current modulation in pediatric and adult chest CT.

PURPOSE: To investigate the effect of scan projection radiography (SPR) coverage on tube current modulation in pediatric and adult thoracic CT examinations. METHODS: Sixty pediatric and 60 adult chest CT examinations were retrospectively studied to determine the incidence rate of examinations involving SPRs that did not include the entire image volume (IV) or the entire primarily exposed body volume (PEBV). The routine chest CT acquisition procedure on a modern 64-slice CT system was imitated on five anthropomorphic phantoms of different size. SPRs of varying length were successively acquired. The same IV was prescribed each time and the computed tube current modulation plan was recorded. The SPR boundaries were altered symmetrically by several steps of ±10mm with respect to the IV boundaries. RESULTS: The upper IV boundary was found to be excluded from SPR in 52% of pediatric and 40% adult chest CT examinations. The corresponding values for the lower boundary were 15% and 20%, respectively. The computed tube current modulation was found to be considerably affected when the SPR did not encompass the entire IV. SPR deficit of 3cm was found to induce up to 46% increase in the computed tube current value to be applied during the first tube rotations over lung apex. CONCLUSIONS: The tube current modulation mechanism functions properly only if the IV set by the operator is entirely included in the localizing SPR image. Operators should cautiously set the SPR boundaries to avoid partial exclusion of prescribed IV from SPRs and thus achieve optimum tube current modulation.

A breathing movement sensor for chest radiography during inspiration in children aged less than 3 years: a prospective randomized controlled study.

Chest radiographs should be obtained at the peak of inspiration so that radiological findings can be precisely interpreted. However, this is not easily achieved, particularly in young children who do not follow the instruction to hold their breath. We developed a sensor that detects the breathing movements and conducted a randomized controlled study to determine whether the sensor would increase the proportion of chest radiographs obtained in the inspiration phase. We recruited 124 infants and children aged less than 3 years, who visited the pediatric department of a general hospital in Tokyo, Japan, and allocated them into one of two groups: with-sensor and without-sensor groups. Overall, 81% of all images were obtained during inspiration. The proportion of chest radiographs taken during inspiration was not statistically different between the two groups (81% vs. 82%). In the with-sensor group, radiologic technologists were able to obtain chest radiographs of the same quality while not observing the chest movement, but the sensor. The use of the sensor did not increase the proportion of chest radiographs taken in the inspiration phase in this study. However, this null result may indicate the possibility of utilizing the sensor for automatizing chest radiography in the future.

Determination of radiation dose and low-dose protocol for digital chest tomosynthesis using radiophotoluminescent (RPL) glass dosimeters.

PURPOSE: This study aimed to determine a low-dose protocol for digital chest tomosynthesis (DTS). METHODS: Five simulated nodules with a CT number of approximately 100 HU with size diameter of 3, 5, 8, 10, and 12 mm were inserted into an anthropomorphic chest phantom (N1 Lungman model), and then scanned by DTS system (Definium 8000) with varying tube voltage, copper filter thickness, and dose ratio. Three radiophotoluminescent (RPL) glass dosimeters, type GD-352 M with a dimension of 1.5 × 12 mm, were used to measure the entrance surface air kerma (ESAK) in each protocol. The effective dose (ED) was calculated using the recorded total dose-area-product (DAP). The signal-to-noise ratio (SNR) was determined for qualitative image quality evaluation. The image criteria and nodule detection capability were scored by two experienced radiologists. The selected low-dose protocol was further applied in a clinical study with 30 pulmonary nodule follow-up patients. RESULTS: The average ESAK obtained from the standard default protocol was 1.68 ± 0.15 mGy, while an ESAK of 0.47 ± 0.02 mGy was found for a low-dose protocol. The EDs for the default and low-dose protocols were 313.98 ± 0.72 µSv and 100.55 ± 0.28 µSv, respectively. There were small non-significant differences in the image criteria and nodule detection scoring between the low-dose and default protocols interpreted by two radiologists. The effective dose of 98.87 ± 0.08 µSv was obtained in clinical study after applying the low-dose protocol. CONCLUSIONS: The low-dose protocol obtained in this study can substantially reduce radiation dose while preserving an acceptable image quality compared to the standard protocol.

Portable chest X-ray in coronavirus disease-19 (COVID-19): A pictorial review.

As the global pandemic of coronavirus disease-19 (COVID-19) progresses, many physicians in a wide variety of specialties continue to play pivotal roles in diagnosis and management. In radiology, much of the literature to date has focused on chest CT manifestations of COVID-19 (Zhou et al. [1]; Chung et al. [2]). However, due to infection control issues related to patient transport to CT suites, the inefficiencies introduced in CT room decontamination, and lack of CT availability in parts of the world, portable chest radiography (CXR) will likely be the most commonly utilized modality for identification and follow up of lung abnormalities. In fact, the American College of Radiology (ACR) notes that CT decontamination required after scanning COVID-19 patients may disrupt radiological service availability and suggests that portable chest radiography may be considered to minimize the risk of cross-infection (American College of Radiology [3]). Furthermore, in cases of high clinical suspicion for COVID-19, a positive CXR may obviate the need for CT. Additionally, CXR utilization for early disease detection may also play a vital role in areas around the world with limited access to reliable real-time reverse transcription polymerase chain reaction (RT-PCR) COVID testing. The purpose of this pictorial review article is to describe the most common manifestations and patterns of lung abnormality on CXR in COVID-19 in order to equip the medical community in its efforts to combat this pandemic.

The Role of Chest Imaging in Patient Management during the COVID-19 Pandemic: A Multinational Consensus Statement from the Fleischner Society.

With more than 900 000 confirmed cases worldwide and nearly 50 000 deaths during the first 3 months of 2020, the coronavirus disease 2019 (COVID-19) pandemic has emerged as an unprecedented health care crisis. The spread of COVID-19 has been heterogeneous, resulting in some regions having sporadic transmission and relatively few hospitalized patients with COVID-19 and others having community transmission that has led to overwhelming numbers of severe cases. For these regions, health care delivery has been disrupted and compromised by critical resource constraints in diagnostic testing, hospital beds, ventilators, and health care workers who have fallen ill to the virus exacerbated by shortages of personal protective equipment. Although mild cases mimic common upper respiratory viral infections, respiratory dysfunction becomes the principal source of morbidity and mortality as the disease advances. Thoracic imaging with chest radiography and CT are key tools for pulmonary disease diagnosis and management, but their role in the management of COVID-19 has not been considered within the multivariable context of the severity of respiratory disease, pretest probability, risk factors for disease progression, and critical resource constraints. To address this deficit, a multidisciplinary panel comprised principally of radiologists and pulmonologists from 10 countries with experience managing patients with COVID-19 across a spectrum of health care environments evaluated the utility of imaging within three scenarios representing varying risk factors, community conditions, and resource constraints. Fourteen key questions, corresponding to 11 decision points within the three scenarios and three additional clinical situations, were rated by the panel based on the anticipated value of the information that thoracic imaging would be expected to provide. The results were aggregated, resulting in five main and three additional recommendations intended to guide medical practitioners in the use of chest radiography and CT in the management of COVID-19.

Utility and validity of dynamic chest radiography in cystic fibrosis (dynamic CF): an observational, non-controlled, non-randomised, single-centre, prospective study.

INTRODUCTION: Dynamic chest radiography (DCR) uses novel, low-dose radiographic technology to capture images of the thoracic cavity while in motion. Pulmonary function testing is important in cystic fibrosis (CF). The tolerability, rapid acquisition and lower radiation and cost compared with CT imaging may make DCR a useful adjunct to current standards of care. METHODS AND ANALYSIS: This is an observational, non-controlled, non-randomised, single-centre, prospective study. This study is conducted at the Liverpool Heart and Chest Hospital (LHCH) adult CF unit. Participants are adults with CF. This study reviews DCR taken during routine CF Annual Review (n=150), validates DCR-derived lung volumes against whole body plethysmography (n=20) and examines DCR at the start and end of pulmonary exacerbations of CF (n=20). The primary objectives of this study are to examine if DCR provides lung function information that correlates with PFT, and lung volumes that correlate whole body plethysmography. ETHICS AND DISSEMINATION: This study has received the following approvals: HRA REC (11 December 2019) and LHCH R&I (11 October 2019). Results are made available to people with CF, the funders and other researchers. Processed, anonymised data are available from the research team on request. TRIAL REGISTRATION NUMBER: ISRCTN 64994816.

Detectability of pulmonary nodules on chest radiographs: bone suppression versus standard technique with single versus dual monitors for visualization.

PURPOSE: To evaluate the diagnostic accuracy of bone suppression imaging (BSI) in the detection of pulmonary nodules on chest radiographs (CXRs) and the effect of visualization method (single or dual monitors) on diagnostic accuracy. MATERIALS AND METHODS: Ten observers interpreted the CXRs of 100 patients: 50 with a T1 lung cancer nodule and 50 without nodules. Each standard CXR was first read alone and then in combination with the corresponding BSI. Two sessions of viewing were conducted: (1) the standard CXR and BSI were placed side by side on dual monitors and (2) both images were shown on the same monitor in alternation. The nodule location, confidence level, and interpretation time were recorded and analyzed statistically. RESULTS: When BSI was added, the area under the receiver operating characteristic curve (AUC) improved with dual monitors and a single monitor. The AUC was not significantly different between the dual-monitor and single-monitor sessions; however, the specificity with BSI and dual monitors decreased. The total interpretation time was significantly shorter with a single monitor than with dual monitors. CONCLUSIONS: The use of BSI improved detectability of T1 lung cancer nodules on CXRs; however, specificity and reading time were affected by the visualization method.

Diagnosis of foreign body aspiration with ultralow-dose CT using a tin filter: a comparison study.

PURPOSE: Suspected airway foreign body aspiration (FBA) is a common event in paediatric emergency units, especially in children under 3 years of age. It can be a life-threatening event if not diagnosed promptly and accurately. The purpose of this study is to compare the diagnostic performance of an ultralow-dose CT (DLP of around 1 mGycm) with that of conventional radiographic methods (fluoroscopy and chest radiography of the airways) in the diagnosis of FBA children's airways. METHODS: Retrospective cross-sectional study. Data from 136 children were collected: 75 were examined with conventional radiographic methods and 61 with ultralow-dose CT. Effective doses were compared using independent t tests. The results of bronchoscopy, if performed, were used in creating contingency 2 × 2 tables to assess the diagnostic performance between modalities. An extra triple reading of all images was applied for this purpose. RESULTS: The effective doses used in the ultralow-dose CT examinations were lower compared with those in conventional methods (p < 0.001). The median dose for CT was 0.04 mSv compared with 0.1 mSv for conventional methods. Sensitivity and specificity were higher for ultralow-dose CT than those for conventional methods (100% and 98% versus 33% and 96%) as were the positive and negative predicted values (90% and 100% versus 60% and 91%). CONCLUSION: Ultralow-dose CT can be used as the imaging of choice in the diagnosis of airway FBA in emergency settings, thereby avoiding concerns about radiation doses and negative bronchoscopy outcomes.