Ultralow-dose Protocols Research Articles

Accuracy of Ultralow-Dose Photon-counting CT in the Detection of Lung Changes after Lung Transplant.

Background Data on the diagnostic accuracy of ultralow-dose (ULD) CT protocols for periodic surveillance in recipients of lung transplant are lacking. Purpose To assess the potential for radiation dose reduction using ULD photon-counting CT (PCT) to detect lung abnormalities in recipients of lung transplant during repeat CT follow-up. Materials and Methods Consecutive adult recipients of lung transplant undergoing same-day standard-of-care low-dose (LD) and ULD PCT from March 2023 to May 2023 were prospectively included. The ULD protocols were performed with two target effective doses comprising 20% (hereafter, ULD1) and 10% (hereafter, ULD2) of the standard LD protocol. The 1-mm reconstructions were reviewed by three readers. Subjective image quality, the visibility of certain anatomic structures (using a five-point Likert scale), and the presence of lung abnormalities were independently assessed. The χ2 or t tests were used to evaluate differences between the ULD1 and ULD2 protocols. Results A total of 82 participants (median age, 64 years [IQR, 54-69 years]; 47 male) were included (41 participants for each ULD protocol). The mean effective doses per protocol were 1.41 mSv ± 0.44 (SD) for LD, 0.26 mSv ± 0.08 for ULD1, and 0.17 mSv ± 0.04 for ULD2. According to three readers, the subjective image quality of the ULD images was deemed diagnostic (Likert score ≥3) in 39-40 (ULD1) and 40-41 (ULD2) participants, and anatomic structures could be adequately visualized (Likert score ≥3) in 33-41 (ULD1) and 34-41 (ULD2) participants. The detection accuracy for individual lung anomalies exceeded 70% for both ULD protocols, except for readers 1 and 3 detecting proximal bronchiectasis and reader 3 detecting bronchial wall thickening and air trapping. No evidence of a statistically significant difference in noise (P = .96), signal-to-noise ratio (P = .77), or reader accuracy (all P ≥ .05) was noted between the ULD protocols. Conclusion ULD PCT was feasible for detecting lung abnormalities following lung transplant, with a tenfold radiation dose reduction. © RSNA, 2024 Supplemental material is available for this article. See also the editorial by Ciet in this issue.

The added effect of artifact reduction algorithm and ultra-low dose protocols on the accuracy of measurements obtained using Planmeca Viso G7 cone beam computed tomography

Objective The aim of this study is to evaluate the accuracy of linear and volumetric measurements using Planmeca Viso G7 cone beam computed tomography (CBCT) examinations acquired with ultra-low dose (ULD) and metal artifact reduction algorithm (ARA) protocols. Materials and methods Eight metallic spherical objects different in size with pre scanning diameter measurements using a calibrated digital caliper were fixed on a five dry human mandible. The real physical diameters and linear measurements between the metallic objects were measured. A CBCT acquisition was obtained four times with the same proper field of view, 150 μm and 100 Kv, in four scans using the Planmeca Viso G7 CBCT, machine acquisition was done with and without ARA, ULD, which is ARA, and ULD. Both acquisition protocols are inherited options in the Planmeca Viso G7 CBCT machine. All images were interpreted with the Planmeca Romexis software. Results Linear and volumetric measurements were found to have a nonstatistically significant difference with real measurements in the acquisition with ARA and ULD, but with a statistically significant difference with the other three acquisition sequences. Conclusions Using the ARA in combination with the ULD as an acquisition tool in the CBCT machine results in accurate linear and volumetric measurements, enhances image quality, and reduces metallic artifact with the lowest radiation dose.

Practical guidance to reduce radiation exposure in electrophysiology applying ultra low-dose protocols: a European Heart Rhythm Association review.

Interventional electrophysiology offers a great variety of treatment options to patients suffering from symptomatic cardiac arrhythmia. Catheter ablation of supraventricular and ventricular tachycardia has globally evolved a cornerstone in modern arrhythmia management. Complex interventional electrophysiological procedures engaging multiple ablation tools have been developed over the past decades. Fluoroscopy enabled interventional electrophysiologist throughout the years to gain profound knowledge on intracardiac anatomy and catheter movement inside the cardiac cavities and hence develop specific ablation approaches. However, the application of X-ray technologies imposes serious health risks to patients and operators. To reduce the use of fluoroscopy during interventional electrophysiological procedures to the possibly lowest degree and to establish an optimal protection of patients and operators in cases of fluoroscopy is the main goal of modern radiation management. The present manuscript gives an overview of possible strategies of fluoroscopy reduction and specific radiation protection strategies.

Comparison of subjective image analysis and effective dose between low-dose cone-beam computed tomography machines.

To compare the cone-beam computed tomography (CBCT) image quality and effective dose between low-dose scanning and standard manufacturer-recommended protocols among different CBCT units. Three human-equivalent phantoms were scanned using the ultra-low-dose (ULD), low dose (LD), and standard dose (STD) modes of ProMax 3D Mid (Planmeca Oy, Helsinki, Finland) and Orthophos SL (Sirona, Bensheim, German) for the CBCT images. The quality of the dental anatomical images was assessed by four experienced oral and maxillofacial radiologists using a 5-point Likert scale. OnDemand3D (Cybermed Co., Seoul, Korea) was used as the third-party software for viewing. The percentage of absolute agreement was calculated to determine intra- and interrater agreements among the observers. The effective doses for all CBCT scanning protocols were also calculated. The STD protocol yielded a higher image quality than did the ULD and LD protocols in both ProMax 3D Mid and Orthophos SL. The ULD and LD protocols demonstrated an "acceptable-to-good" sense of visual perception of the CBCT images. The visibility scores significantly differed between the ULD and LD and the STD protocols in ProMax 3D Mid and Orthophos SL, except for the 120-kVp setting in ProMax 3D Mid. The average intra- and interrater agreement scores ranged from 0.63 to 0.89 and from 0.44 to 0.76, respectively. The ULD and LD protocols reduced the radiation dose sixfold compared with the STD protocol. High-tube-voltage protocols could remarkably reduce the imaging dose without degrading the image quality. Specifically, ULD and LD CBCT protocols may be adopted as routine practice for diagnosis and treatment planning.

Evaluation of AI-Based Segmentation Tools for COVID-19 Lung Lesions on Conventional and Ultra-low Dose CT Scans.

A reliable diagnosis and accurate monitoring are pivotal steps for treatment and prevention of COVID-19. Chest computed tomography (CT) has been considered a crucial diagnostic imaging technique for the injury assessment of the viral pneumonia. Furthermore, the automatization of the segmentation methods for lung alterations helps to speed up the diagnosis and lighten radiologists’ workload. Considering the assiduous pathology monitoring, ultra-low dose (ULD) chest CT protocols have been implemented to drastically reduce the radiation burden. Unfortunately, the available AI technologies have not been trained on ULD-CT data and validated and their applicability deserves careful evaluation. Therefore, this work aims to compare the results of available AI tools (BCUnet, CORADS AI, NVIDIA CLARA Train SDK and CT Pneumonia Analysis) on a dataset of 73 CT examinations acquired both with conventional dose (CD) and ULD protocols. COVID-19 volume percentage, resulting from each tool, was statistically compared. This study demonstrated high comparability of the results on CD-CT and ULD-CT data among the four AI tools, with high correlation between the results obtained on both protocols (R > .68, P < .001, for all AI tools).

Efficacy of low dose and ultra-low dose on the visibility of peri-implant fenestration and dehiscences: a computed tomography study.

PurposeThis study aimed to evaluate the visibility of peri-implant fenestration and dehiscences on computed tomography (CT) images taken with 2 different doses.Material and methodsThe defects were created on the apical of 6 implants randomly selected from 20 titanium implants placed in the ribs, and dehiscences were created on the cervical of 8 implants. No defects were created around 6 implants. Macroscopic analysis of the implanted ribs was accepted as the gold standard. From the samples, images were taken by using both ultra-low dose (80 kVp, 50 mA, 1.25 mm slice thickness) and low dose (100 kVp, 50 mA, 1.25 mm slice thickness) protocols in CT. The images obtained were evaluated using a 5-point scale.ResultsNo significant difference was found between the area under the receiver operating characteristic of ultra-low dose protocol and low dose protocol in both defects based on the Wilcoxon test (p > 0.05).ConclusionsThe ultra-low dose protocol could be applied by adhering to the “as low as reasonably achievable” principle in the diagnosis of peri-implant defects.

Computed tomography colonography and radiation risk: How low can we go?

Computed tomography colonography (CTC) has become a key examination in detecting colonic polyps and colorectal carcinoma (CRC). It is particularly useful after incomplete optical colonoscopy (OC) for patients with sedation risks and patients anxious about the risks or potential discomfort associated with OC. CTC's main advantages compared with OC are its non-invasive nature, better patient compliance, and the ability to assess the extracolonic disease. Despite these advantages, ionizing radiation remains the most significant burden of CTC. This opinion review comprehensively addresses the radiation risk of CTC, incorporating imaging technology refinements such as automatic tube current modulation, filtered back projections, lowering the tube voltage, and iterative reconstructions as tools for optimizing low and ultra-low dose protocols of CTC. Future perspectives arise from integrating artificial intelligence in computed tomography machines for the screening of CRC.

Dosimetry and Comparison between Different CT Protocols (Low Dose, Ultralow Dose, and Conventional CT) for Lung Nodules' Detection in a Phantom.

Background The effects of dose reduction in lung nodule detection need better understanding. Purpose To compare the detection rate of simulated lung nodules in a chest phantom using different computed tomography protocols, low dose (LD), ultralow dose (ULD), and conventional (CCT), and to quantify their respective amount of radiation. Materials and Methods A chest phantom containing 93 simulated lung nodules was scanned using five different protocols: ULD (80 kVp/30 mA), LD A (120 kVp/20 mA), LD B (100 kVp/30 mA), LD C (120 kVp/30 mA), and CCT (120 kVp/automatic mA). Four chest radiologists analyzed a selected image from each protocol and registered in diagrams the nodules they detected. Kruskal–Wallis and McNemar's tests were performed to determine the difference in nodule detection. Equivalent doses were estimated by placing thermoluminescent dosimeters on the surface and inside the phantom. Results There was no significant difference in lung nodules' detection when comparing ULD and LD protocols (p=0.208 to p=1.000), but there was a significant difference when comparing each one of those against CCT (p < 0.001). The detection rate of nodules with CT attenuation values lower than −600 HU was also different when comparing all protocols against CCT (p < 0.001 to p=0.007). There was at least moderate agreement between observers in all protocols (κ-value >0.41). Equivalent dose values ranged from 0.5 to 9 mSv. Conclusion There is no significant difference in simulated lung nodules' detection when comparing ULD and LD protocols, but both differ from CCT, especially when considering lower-attenuating nodules.

Validation of iterative CT reconstruction by inter and intra observer performance assessment of artificial lung foci

Abstract We investigate the suitability of statistical and model-based iterative reconstruction (IR) algorithm strengths and their influence on image quality and diagnostic performance in low-dose computer tomography (CT) protocols for lung-cancer screening procedures. We evaluate the inter- and intra-observer performance for the assessment of iterative CT reconstruction. Artificial lung foci shaped as spheres and spicules made from material with calibrated Hounsfield units were pressed within layered granules in lung lobes of an anthropomorphic phantom. Adaptively, a soft-tissue- and fat- extension ring were attached. The phantom with foci was scanned using standard high contrast, low-dose and ultra lowdose protocols. For reconstruction the IR algorithm ADMIRE at four different strength levels were used. Two ranking tests and Friedman statistics were performed. Fleiss k and modified Cohen’s kneywere used to quantify inter- and intra-observer performance. In conjunction with the standard lung kernel BL75 radiologists evaluated medium to high IR strength, with preference to S4, as suitable for lung foci detection. When varying reconstruction kernels the ranking became more random than with varying phantom diameter. The inter-observer reliability shows poor to slight agreement expressed by k&lt;0 and k=0-0.20 . For the intra-observer reliability non- agreement with kney=0-0.20and moderate agreement with kney=0.60-0.79 for the first ranking test, and almost perfect agreement with kney&gt;0.90 for the second ranking test was observed. In conclusion, our validation suggests radiological preference of medium to high iteration strengths, especially S4, for lung foci detection. An investigation of the correlation between diagnostic experience and the subjective perception of IR reconstructed CT images still needs to be investigated.

Effect of tin filter-based spectral shaping CT on image quality and radiation dose for routine use on ultralow-dose CT protocols: A phantom study

PurposeThe purpose of this study was to assess the impact of tin filter (TF) on X-ray beam quality, image quality and radiation dose and its suitability for routine use for chest and lumbar-spine/pelvis-hip ultralow-dose (ULD) CT examination protocols. Materials and methodsThe X-ray beam quality was determined by measuring the half-value layer (HVL) and calculating the mean weighted energy for 100, 120, 150kVp (using standard filtration) and for 100 and 150kVp using TF (Sn100kVp and Sn150kVp, respectively). Acquisitions were performed on a phantom at four dose levels for each previously definedkVp. The mean attenuation (NCT), noise-power-spectrum (NPS) and task-based transfer function (TTF) were computed. The detectability index (d’) was computed to model the detection of two lesions in spine and pelvic/hip examination and two for chest exploration. Image quality and detectability using a TF were assessed for two routinely used ULD protocols. ResultsThe HVL and mean weighted energy increased using a TF for the same tube voltage. Using a TF for the same tube voltage changed NCT for bone and acrylic inserts, decreased the NPS peak without changing the NPS spatial frequency and increased the TTF values. The d’ values were improved using a TF and with the dose increase. d’ values of all modeled lesions were improved using Sn100kVp and Sn150kVp for the lumbar-spine/pelvis-hip and chest ULD protocols except for sclerotic bone lesion using Sn150kVp. ConclusionThe use of TF increases the X-ray beam quality and improves the image quality characteristics in phantom images, thus appearing as a promising tool for reducing dose and/or improving the image quality of ULD protocols.

CT dose optimization for the detection of pulmonary arteriovenous malformation (PAVM): A phantom study

PurposeTo determine the lowest suitable dose level for the detection of pulmonary arteriovenous malformation (PAVM) using a task-based image quality assessment. Material and methodsA phantom was scanned using the standard chest protocol (STD) and 4 other ultra-low dose protocols (ULD) using various kVp. Raw data were reconstructed using level 5 of the hybrid iterative reconstruction algorithm (iDose4) for the STD protocol, and level 6 of iDose4 and levels 1 to 3 of model-based iterative reconstruction (IMR) for the ULD protocols. Both quantitative criteria and qualitative analysis were used to compare protocols. Noise-power-spectrum and Task-based transfer function were computed using imQuest software. The detectability-index (d’) was computed for the detection of PAVM. A subjective analysis was performed by 2 chest radiologists to validate the image-quality obtained on the anthropomorphic phantom for all protocols. ResultsSimilar d’ values were found for ULD-140 using iDose4 6 compared to STD protocol. Greater d’ values were found for all ULD protocols using IMR compared to STD. Subjective image quality was rated as acceptable to excellent for ULD-140 and ULD-120 for all reconstruction types, for ULD-100 and ULD-80 using IMR2, and for ULD-100 using IMR1. Image smoothing was poor for IMR3 for ULD-100 and ULD-80. Finally, the ULD-80 protocol reconstructed with IMR2 was chosen for the detection of PAVM. With this protocol, the dose (CTDIvol of 0.3mGy) was reduced by 91% compared with the STD protocol. ConclusionA dose level as low as 0.3mGy reconstructed with IMR2 provides an image quality suitable for the detection of PAVM.

Design and first results of a phantom study on the suitability of iterative reconstruction for lung-cancer screening with low-dose computer tomography

Abstract In this research computer tomography (CT) iterative reconstruction (IR) algorithms are investigated, specifically the impact of their statistical and model-based strength on image quality in low-dose lung screening CT protocols in comparison to filtered back projection (FBP). It has been probed whether statistical, model-based IR in conjunction with low-dose, and ultra-low-dose protocols are suitable for lungcancer screening. To this end, artificial lung nodules shaped as spheres and spicules made from material with calibrated Hounsfield units (HU) were attached on marked positions in the lung structure of an anthropomorphic phantom. Nodule positions were selected by distinguished radiologists. The phantom with nodules was scanned on a CT Scanner using standard high contrast (SHC), low-dose (LD) and ultra low-dose (ULD) protocol. For reconstruction FBP and the IR algorithm ADMIRE at three different strength levels were used. Volume CT dose index (CTDIvol) and dose-length product were recorded. Radiologists assessed subjective image quality using a six-point Likert scale by reading all image series in terms detectability of lung nodules. As a measurable objective image quality parameter signal-to-noise ratios (SNR) were investigated. The CTDIvol decreases by more than 70% for all protocols and nodules compared to diagnostic reference value for chest CT (p&lt;0.00001). The evaluation of image quality parameters, i.e. SNR, indicates that LD and ULD protocols in conjunction with IR assert high quality lung-nodule detection. The results reveal that IR algorithm with moderate to high strength is an indispensable alternative to FBP in low-dose scanning, thus, potentially suitable for lung-tumour screening.

CT of Kidney Volume in Autosomal Dominant Polycystic Kidney Disease: Accuracy, Reproducibility, and Radiation Dose.

Background Total kidney volume (TKV) assessment is valuable in autosomal dominant polycystic kidney disease (ADPKD) but the reference standard method of MRI planimetry requires access to MRI and time-consuming interpretation. Purpose To determine whether accurate TKV measurements comparable to the resource-intensive reference standard of MRI planimetry can be obtained by using alternate methods including dose-reducing CT protocols and time-saving measurement equations. Materials and Methods In this prospective study conducted September 2016 to June 2017, adult participants with ADPKD underwent one MRI and two CT examinations. Low-dose (LD) and ultra-low-dose (ULD) CT examinations were performed with radiation doses 1.4 and 2.6 times lower, respectively, than the authors' institution's standard abdomen and pelvis CT. ULD CT examinations were reconstructed via model-based iterative reconstruction. Three TKV measurement equations were applied to all image sets, and MRI manual planimetry was the reference standard. Spearman correlation with the reference standard, simple linear regression, and root mean square error (RMSE) calculation analyzed accuracy of these methods; intraclass correlation coefficient examined reproducibility. Results Thirty participants (mean age, 41 years; age range, 24-67 years) had a mean TKV of 1368.9 mL ± 1146.13 (standard deviation). The ULD and LD CT protocols had median dose-length product of 58.8 and 115.5 mGy ∙ cm, respectively (P = .01), and CT dose index of 1.2 and 3.9 mGy, respectively (P < .001). All imaging modalities and measurement equations had excellent correlation with the reference standard (r2 > 0.98). RMSE ranged from 80.5 to 157.3 mL (5.9%-11.5% of mean TKV). Intraclass correlation coefficients were greater than 0.98 for all methods. Mean measurement times for the ellipsoid method ranged from 4.6 to 5.2 minutes compared with a mean of 27.7 minutes (range, 14-60 minutes) for manual planimetry. Conclusion Accurate and reproducible total kidney volume measurements comparable to the reference standard of MRI planimetry can be obtained by using a dose-minimizing ultra-low-dose CT protocol and volume measurement based on discrete linear measurements. © RSNA, 2019 Online supplemental material is available for this article.

To investigate dose reduction and comparability of standard dose CT vs Ultra low dose CT in evaluating pulmonary emphysema

ObjectivesThe aim of this study was to investigate the extent of dose reduction and comparability of standard dose CT vs Ultra low dose CT in evaluating pulmonary emphysema. MethodsForty-nine patients with emphysema were recruited from a tertiary referral respiratory clinic. Each patient had a non-contrast Standard Dose (SD) and Ultra Low Dose (ULD) thoracic CT. The images were reconstructed using contemporary iterative reconstruction with a standard lung kernel. Lung volumes and emphysema severity was calculated using a commercially available automated densitometry segmentation package. The effective dose was calculated for both CT protocols. ResultsAutomated densitometry calculated the total lung volume and percentage lung area of emphysema. The findings were highly comparable between ULD and SD protocols. A strong correlation was seen between ULD and SD images in measurement of total lung volume (R = 0.925, p < 0.001) and percentage lung involvement by densitometry (R = 0.940, p < 0.001). There is a 95% dose reduction with the ULD protocol, the mean effective dose is 0.12 ± 0.09 mSv versus 2.33 ± 1.54 mSv for the SD protocol. ConclusionsULD thoracic CT is a comparable protocol for the assessment of emphysema severity relative to standard dose CT. ULD CT is performed at a 95% dose reduction compared to SD CT.

Comparison of low- and ultralow-dose computed tomography protocols for quantitative lung and airway assessment.

Quantitative computed tomography (CT) measures are increasingly being developed and used to characterize lung disease. With recent advances in CT technologies, we sought to evaluate the quantitative accuracy of lung imaging at low- and ultralow-radiation doses with the use of iterative reconstruction (IR), tube current modulation (TCM), and spectral shaping. We investigated the effect of five independent CT protocols reconstructed with IR on quantitative airway measures and global lung measures using an invivo large animal model as a human subject surrogate. A control protocol was chosen (NIH-SPIROMICS+TCM) and five independent protocols investigating TCM, low- and ultralow-radiation dose, and spectral shaping. For all scans, quantitative global parenchymal measurements (mean, median and standard deviation of the parenchymal HU, along with measures of emphysema) and global airway measurements (number of segmented airways and pi10) were generated. In addition, selected individual airway measurements (minor and major inner diameter, wall thickness, inner and outer area, inner and outer perimeter, wall area fraction, and inner equivalent circle diameter) were evaluated. Comparisons were made between control and target protocols using difference and repeatability measures. Estimated CT volume dose index (CTDIvol) across all protocols ranged from 7.32mGy to 0.32mGy. Low- and ultralow-dose protocols required more manual editing and resolved fewer airway branches; yet, comparable pi10 whole lung measures were observed across all protocols. Similar trends in acquired parenchymal and airway measurements were observed across all protocols, with increased measurement differences using the ultralow-dose protocols. However, for small airways (1.9±0.2mm) and medium airways (5.7±0.4mm), the measurement differences across all protocols were comparable to the control protocol repeatability across breath holds. Diameters, wall thickness, wall area fraction, and equivalent diameter had smaller measurement differences than area and perimeter measurements. In conclusion, the use of IR with low- and ultralow-dose CT protocols with CT volume dose indices down to 0.32mGy maintains selected quantitative parenchymal and airway measurements relevant to pulmonary disease characterization.

Spatial and contrast resolution of ultralow dose dentomaxillofacial CT imaging using iterative reconstruction technology.

The objective of this study was to determine how iterative reconstruction technology (IRT) influences contrast and spatial resolution in ultralow-dose dentomaxillofacial CT imaging. A polymethyl methacrylate phantom with various inserts was scanned using a reference protocol (RP) at CT dose index volume 36.56 mGy, a sinus protocol at 18.28 mGy and ultralow-dose protocols (LD) at 4.17 mGy, 2.36 mGy, 0.99 mGy and 0.53 mGy. All data sets were reconstructed using filtered back projection (FBP) and the following IRTs: adaptive statistical iterative reconstructions (ASIRs) (ASIR-50, ASIR-100) and model-based iterative reconstruction (MBIR). Inserts containing line-pair patterns and contrast detail patterns for three different materials were scored by three observers. Observer agreement was analyzed using Cohen's kappa and difference in performance between the protocols and reconstruction was analyzed with Dunn's test at α = 0.05. Interobserver agreement was acceptable with a mean kappa value of 0.59. Compared with the RP using FBP, similar scores were achieved at 2.36 mGy using MBIR. MIBR reconstructions showed the highest noise suppression as well as good contrast even at the lowest doses. Overall, ASIR reconstructions did not outperform FBP. LD and MBIR at a dose reduction of >90% may show no significant differences in spatial and contrast resolution compared with an RP and FBP. Ultralow-dose CT and IRT should be further explored in clinical studies.

MP82-16 CT FOR EVALUATION OF UROLITHIASIS: IMAGE QUALITY OF ULTRALOW-DOSE (SUB MSV) CT WITH KNOWLEDGE-BASED ITERATIVE RECONSTRUCTION AND DIAGNOSTIC PERFORMANCE OF LOW-DOSE CT WITH STATISTICAL ITERATIVE RECONSTRUCTION

You have accessJournal of UrologyStone Disease: Epidemiology & Evaluation I1 Apr 2016MP82-16 CT FOR EVALUATION OF UROLITHIASIS: IMAGE QUALITY OF ULTRALOW-DOSE (SUB MSV) CT WITH KNOWLEDGE-BASED ITERATIVE RECONSTRUCTION AND DIAGNOSTIC PERFORMANCE OF LOW-DOSE CT WITH STATISTICAL ITERATIVE RECONSTRUCTION Jin wook Kim, Young Tae Moon, Kyung Do Kim, Tae-Hyoung Kim, Soon Chul Myung, Seung Hyun Ahn, Jae Duck Choi, Jung Hoon Kim, Min Soo Kim, Shin Young Lee, Byung Hoon Chi, and In Ho Chang Jin wook KimJin wook Kim More articles by this author , Young Tae MoonYoung Tae Moon More articles by this author , Kyung Do KimKyung Do Kim More articles by this author , Tae-Hyoung KimTae-Hyoung Kim More articles by this author , Soon Chul MyungSoon Chul Myung More articles by this author , Seung Hyun AhnSeung Hyun Ahn More articles by this author , Jae Duck ChoiJae Duck Choi More articles by this author , Jung Hoon KimJung Hoon Kim More articles by this author , Min Soo KimMin Soo Kim More articles by this author , Shin Young LeeShin Young Lee More articles by this author , Byung Hoon ChiByung Hoon Chi More articles by this author , and In Ho ChangIn Ho Chang More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2016.02.2157AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES To compare radiation dose and image quality in regular, low, and ultralow-dose CT protocols, and to evaluate diagnostic performance of low-dose CT for urolithiasis. METHODS Sixty-five patients with suspected urolithiasis underwent three different scans under the regular, low, and ultralow-dose protocols. The regular dose scans were reconstructed using filtered back projection and the low-dose scans were reconstructed using a statistical iterative reconstruction. The ultralow-dose scans were reconstructed using both techniques in addition to a knowledge-based IR. Effective radiation doses were compared. Objective image noise was assessed by measuring standard deviation of HU and subjective image assessment was performed with a 3- or 5-point scale. Diagnostic performance of the low-dose image was evaluated, using the regular dose image as a standard reference and the interobserver agreement between two reviewers with different levels of experience was calculated. RESULTS The effective radiation dose was significantly different in each protocol (p < 0.001) and estimated dose reduction of the low-dose and ultralow-dose protocols was 76.4% and 89.8%, respectively. The knowledge-based iterative reconstruction algorithm showed poorer subjective image quality than the regular and lowdose protocols, but it also had the least objective image noise. Overall, the low-dose image set showed a greater than 84% concordance rate and 100% in ureter stones larger than 3 mm. Interobserver agreement was substantial (kappa value = 0.61). CONCLUSIONS The knowledge-based IR can provide a better quality image while reducing radiation exposure under the same protocol. Furthermore, the diagnostic performance of the low-dose CT protocol is comparable to the regular dose scan. © 2016FiguresReferencesRelatedDetails Volume 195Issue 4SApril 2016Page: e1079 Advertisement Copyright & Permissions© 2016MetricsAuthor Information Jin wook Kim More articles by this author Young Tae Moon More articles by this author Kyung Do Kim More articles by this author Tae-Hyoung Kim More articles by this author Soon Chul Myung More articles by this author Seung Hyun Ahn More articles by this author Jae Duck Choi More articles by this author Jung Hoon Kim More articles by this author Min Soo Kim More articles by this author Shin Young Lee More articles by this author Byung Hoon Chi More articles by this author In Ho Chang More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Ultralow-dose CT with tin filtration for detection of solid and sub solid pulmonary nodules: a phantom study.

To investigate the diagnostic performance of advanced modelled iterative reconstruction (ADMIRE) to filtered back projection (FBP) when using an ultralow-dose protocol for the detection of solid and subsolid pulmonary nodules. Single-energy CT was performed at 100 kVp with tin filtration in an anthropomorphic chest phantom with solid and subsolid pulmonary nodules (2-10 mm, attenuation, 20 to -800 HU at 120 kVp). The mean volume CT dose index (CTDIvol) of the standard chest protocol was 2.2 mGy. Subsequent scans were obtained at 1/8 (0.28 mGy), 1/20 (0.10 mGy) and 1/70 (0.03 mGy) dose levels by lowering tube voltage and tube current. Images were reconstructed with FBP and ADMIRE. One reader measured image noise; two readers determined image quality and assessed nodule localization. Image noise was significantly reduced using ADMIRE compared with FBP (ADMIRE at a strength level of 5 : 70.4% for 1/20; 71.6% for 1/8; p < 0.001). Interobserver agreement for image quality was excellent (k = 0.88). Image quality was considered diagnostic for all images at 1/20 dose using ADMIRE. Sensitivity of nodule detection was 97.1% (100% for solid, 93.8% for subsolid nodules) at 1/20 dose and 100% for both nodule entities at 1/8 dose using ADMIRE 5. Images obtained with 1/70 dose had moderate sensitivity (overall 85.7%; solid 95%; subsolid 73.3%). Our study suggests that with a combination of tin filtration and ADMIRE, the CTDIvol of chest CT can be lowered considerably, while sensitivity for nodule detection remains high. For solid nodules, CTDIvol was 0.10 mGy, while subsolid nodules required a slightly higher CTDIvol of 0.28 mGy. Detection of subsolid nodules is feasible with ultralow-dose protocols.

CT for evaluation of urolithiasis: image quality of ultralow-dose (Sub mSv) CT with knowledge-based iterative reconstruction and diagnostic performance of low-dose CT with statistical iterative reconstruction.

To compare radiation dose and image quality in regular, low, and ultralow-dose CT protocols, and to evaluate diagnostic performance of low-dose CT for urolithiasis. Sixty-five patients with suspected urolithiasis underwent three different scans under the regular, low, and ultralow-dose protocols. The regular dose scans were reconstructed using filtered back projection and the low-dose scans were reconstructed using a statistical iterative reconstruction. The ultralow-dose scans were reconstructed using both techniques in addition to a knowledge-based IR. Effective radiation doses were compared. Objective image noise was assessed by measuring standard deviation of HU and subjective image assessment was performed with a 3- or 5-point scale. Diagnostic performance of the low-dose image was evaluated, using the regular dose image as a standard reference and the interobserver agreement between two reviewers with different levels of experience was calculated. The effective radiation dose was significantly different in each protocol (p<0.001) and estimated dose reduction of the low-dose and ultralow-dose protocols was 76.4% and 89.8%, respectively. The knowledge-based iterative reconstruction algorithm showed poorer subjective image quality than the regular and low-dose protocols, but it also had the least objective image noise. Overall, the low-dose image set showed a greater than 84% concordance rate and 100% in ureter stones larger than 3mm. Interobserver agreement was substantial (kappa value=0.61). The knowledge-based IR can provide a better quality image while reducing radiation exposure under the same protocol. Furthermore, the diagnostic performance of the low-dose CT protocol is comparable to the regular dose scan.

Ultralow Dose CT Imaging for Navigated Skull Base Surgery Using ASIR and MBIR-2D and 3D Image Quality

Objective: To evaluate 2D and 3D image quality of ultralow dose computed tomography images for navigated skull base surgery using adaptive statistical iterative reconstruction (ASIR) and model-based iterative reconstruction (MBIR) compared with standard filtered back projection (FBP). Study Design: Cadaver study. Material and Methods: A human cadaver head was scanned using a high resolution reference protocol for navigated skull base surgery (CTDIvol 30.48 mGy) and a series of five ultralow dose protocols (3.48, 2.19, 0.82, 0.44, and 0.22 mGy). Subjective image quality of blinded 2D axial and 3D images using FBP and ASIR-50, ASIR-100, and MBIR was evaluated by three observers using top-down scoring. Statistical analyze was performed per protocol and reconstruction including multiple Bonferoni testing (p = 0.05). Results: 2D images: There was no significant difference between the FBP reference 30.48 mGy and the ultralow dose protocol ASIR-50 and 100 at 3.48 mGy, ASIR-100 and MBIR at 2.19, ASIR-100 and MBIR at 0.82, and MBIR at 0.44 mGy. MBIR at 3.48 mGy scored significantly better than the FBP reference (p = 0.004). 3D images: There was no significant difference between the FBP reference and the ultralow dose protocols except FBP and ASIR-50 at 0.44 mGy (p = 0.007, p = 0.013) and ASIR-50 at 0.22 mGy (p = 0.019). Conclusions: ASIR-100 and MBIR significantly improve subjective image quality of ultralow dose imaging and may allow dose reductions of more than 90%.