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Copyright of Equine Veterinary Journal is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Equine Veterinary Journal is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Objective: Distances and angles measured from long-leg radiographs (LLR) are important for surgical decision-making. However, projectional radiography suffers from distortion, potentially generating differences between measurement and true anatomical dimension. These phenomena are not uniform between conventional radiography (CR) digital radiography (DR) and fan-beam technology (EOS). We aimed to identify differences between these modalities in an experimental setup. Materials and methods: A hemiskeleton was stabilized using an external fixator in neutral, valgus and varus knee alignment. Ten images were acquired for each alignment and each modality: one CR setup, two different DR systems, and an EOS. A total of 1680 measurements were acquired and analyzed. Results: We observed great differences for dimensions and angles between the 4 modalities. Femoral head diameter measurements varied in the range of > 5 mm depending on the modality, with EOS being the closest to the true anatomical dimension. With functional leg length, a difference of 8.7% was observed between CR and EOS and with the EOS system being precise in the vertical dimension on physical-technical grounds, this demonstrates significant projectional magnification with CR-LLR. The horizontal distance between the medial malleoli varied by 20 mm between CR and DR, equating to 21% of the mean. Conclusions: Projectional distortion resulting in variations approaching 21% of the mean indicate, that our confidence on measurements from standing LLR may not be justified. It appears likely that among the tested equipment, EOS-generated images are closest to the true anatomical situation most of the time. [ABSTRACT FROM AUTHOR]

Background: Motion induced image artifacts have been the focus of many investigations for x‐ray computed tomography (CT). Methodologies of combating patient motion include the use of gating devices to optimize the data acquisition, reduction in patient scan time via faster gantry rotation and large detector coverage, and the development of advanced reconstruction and post‐processing algorithms to minimize motion artifacts. Purpose: Previously proposed approaches are generally "global" in nature in that motion is characterized for the entire image. It is well known, however, that the presence of motion artifact in a CT image is highly nonuniform. When there is a lack of automated and quantitative local measure indicating the presence and the severity of motion artifacts in a local region, the quality of the reconstructed images depends heavily on the CT operator's rigor and experience. Even when an operator is informed of the presence of motion, little information is provided about the nature of the motion artifact to understand its relevance to the clinical task at hand. In this paper, we propose an image‐space spatial‐ and temporal‐consistency metric (CM) to detect and characterize the local motion. Method: In a non‐rigid human organ, such as the lung, there are many small and rigid objects (target objects), such as blood vessels and nodules, distributed throughout the organ. If motion can be characterized for these target objects, we obtain a complete motion map for the organ. To accomplish this, a preliminary image reconstruction is carried out to identify the target objects and establish region‐of‐interests for consistency‐metric calculation. The CM is then obtained based on the backprojected intensity difference between the object region and its circular background. For a stationary object, the accumulation of this quantity over views is linear. When a target object moves, nonlinear behavior exhibits and a quantitative measure of linearity indicates the severity of motion. Results: Extensive computer simulation was utilized to confirm the validity of the theory. These tests stress the sensitivity of the proposed CM to the target object size, object shape, in‐plane motion, cross‐plane motion, cone‐beam effect, and complex background. Results confirm that the proposed approach is robust under different testing conditions. The proposed CM is further validated using a cardiac scan of a swine, and the proposed CM correlates well with the visual inspection of the artifact in the reconstructed images. Conclusions: In this paper, we have demonstrated the efficacy of the proposed CM for motion detection. Unlike previously proposed approaches where the consistency condition is derived for the entire image or the entire imaging volume, the proposed metric is well localized so that different zones in a patient anatomy can be individually characterized. In addition, the proposed CM provides a quantitative measure on a view‐by‐view basis so that the severity of motion is consistently estimated over time. Such information can be used to optimize the image reconstruction process and minimize the motion artifact. [ABSTRACT FROM AUTHOR]

Background: Dorsoproximal osteochondral defects commonly affect the proximal phalanx, but information about diagnosis on computed tomography (CT) and magnetic resonance imaging (MRI) is limited. Objectives: To assess CT and MRI diagnoses of osteochondral defects, describe the lesions and compare sensitivity and specificity of the modalities using macroscopic pathology as gold standard. Study design: Cross‐sectional study. Methods: Thirty‐five equine cadaver limbs underwent standing cone‐beam CT (CBCT), fan‐beam CT (FBCT), low‐field MRI and pathological examination. CT and MR images were examined for proximal phalanx dorsomedial and dorsolateral eminence osteochondral defects. Defect dimensions were measured. Imaging diagnoses and measurements were compared with macroscopic examination. Results: Fifty‐six defects were seen over 70 potential locations. On CBCT and FBCT, osteochondral defects appeared as subchondral irregularity/saucer‐shaped defects. On MRI, osteochondral defects were a combination of articular cartilage defect on dorsal images and subchondral flattening/irregularity on sagittal images. Subchondral thickening and osseous short tau inversion recovery hyperintensity were found concurrent with osteochondral defects. Compared with pathological examination, the sensitivity and specificity of diagnosis were 86% (95% confidence interval [95% CI] 75%–93%) and 64% (95% CI 38%–85%) for FBCT; 64% (95% CI 51%–76%) and 71% (95% CI 46%–90%) for CBCT; and 52% (95% CI 39%–65%) and 71% (95% CI 46%–90%) for MRI. Sensitivity of all modalities increased with defect size. Macroscopic defect dimensions were strongly correlated with CBCT (r = 0.76, p < 0.001) and moderately correlated with FBCT and MRI (r = 0.65, p < 0.001). Macroscopic measurements were significantly greater than all imaging modality dimensions (p < 0.001), potentially because macroscopy included articular cartilage pathology. Main limitations: Influence of motion artefact could not be assessed. Conclusions: Osteochondral defects could be visualised using both CT and MRI with sensitivity increasing with defect size. Diagnostic performance was best using FBCT, followed by CBCT then MRI, but CBCT‐measured defect size best correlated with macroscopic examination. MRI provided useful information on fluid signal associated with defects, which could represent active pathology. [ABSTRACT FROM AUTHOR]

Summary Background Objective Study design Methods Results Main limitations Conclusions Cone‐beam computed tomography (CBCT) and low‐field magnetic resonance imaging (MRI) are increasingly used in standing horses, so it is important to understand an efficient application of these imaging modalities.To compare CBCT and MRI findings in the metacarpo (MCP)/metatarsophalangeal (MTP) region of clinical patients imaged for diagnostic purposes.Retrospective study.The CBCT and MRI images of the MCP/MTP region from equine clinical patients undergoing both standing MRI and CBCT imaging for lameness localised to the fetlock region (2021–2023) were retrospectively reviewed. Presence, location and imaging features of lesions were compared between modalities using descriptive analysis.Imaging studies of 24 MCP/MTP regions from 22 horses were included. CBCT provided the assessment of subchondral bone integrity in palmar/plantar osteochondral disease, details of the length and associated attenuation changes of third metacarpal/tarsal parasagittal groove and proximal phalanx sagittal groove fissures, structural integrity and attenuation changes of subchondral and trabecular bone injuries, proximal phalanx dorsoproximal defects and anatomical and structural details of proximal sesamoid bone injuries. MRI provided the evaluation of short tau inversion recovery (STIR) hyperintensity associated with bone lesions and the extent of increased fluid accumulation in bone. CBCT revealed reduced joint space, indicating articular cartilage loss, while MRI showed joint distension and synovitis. MRI revealed generalised osseous STIR hyperintensity associated with septic arthritis. Soft tissue injuries were most identified by MRI except for heterotopic mineralisation most detected by CBCT.Imaging findings not verified by a gold standard.CBCT and MRI contributed different diagnostic information so optimal information was obtained by using both modalities. Standing CBCT showed changes in bone structure and attenuation but was limited in detecting soft tissue injuries. Standing MRI showed increased fluid accumulation in bone and soft tissue injuries but was limited in assessing structural details of bone injuries. [ABSTRACT FROM AUTHOR]

Background and purpose: Radiomics analysis extracts quantitative data (features) from medical images. These features could potentially reflect biological characteristics and act as imaging biomarkers within precision medicine. However, there is a lack of cross-comparison and validation of radiomics outputs which is paramount for clinical implementation. In this study, we compared radiomics outputs across two computed tomography (CT)-based preclinical scanners. Materials and methods: Cone beam CT (CBCT) and µCT scans were acquired using different preclinical CT imaging platforms. The reproducibility of radiomics features on each scanner was assessed using a phantom across imaging energies (40 & 60 kVp) and segmentation volumes (44–238 mm3). Retrospective mouse scans were used to compare feature reliability across varying tissue densities (lung, heart, bone), scanners and after voxel size harmonisation. Reliable features had an intraclass correlation coefficient (ICC) > 0.8. Results: First order and GLCM features were the most reliable on both scanners across different volumes. There was an inverse relationship between tissue density and feature reliability, with the highest number of features in lung (CBCT=580, µCT=734) and lowest in bone (CBCT=110, µCT=560). Comparable features for lung and heart tissues increased when voxel sizes were harmonised. We have identified tissue-specific preclinical radiomics signatures in mice for the lung (133), heart (35), and bone (15). Conclusions: Preclinical CBCT and µCT scans can be used for radiomics analysis to support the development of meaningful radiomics signatures. This study demonstrates the importance of standardisation and emphasises the need for multi-centre studies.

Objective: To determine if upper airway characteristics and airway pressure change significantly between low risk, healthy non‐OSA subjects, and OSA subjects during respiration using cone‐beam computed tomography (CBCT) imaging and steady‐state k‐ω model computational fluid dynamics (CFD) fluid flow simulations, respectively. Materials and Methods: CBCT scans were collected at both end‐inhalation and end‐exhalation for 16 low‐risk non‐OSA subjects and compared to existing CBCT data from 7 OSA subjects. The CBCT images were imported into Dolphin Imaging and the upper airway was segmented into stereolithography (STL) files for area and volumetric measurements. Subject models that met pre‐processing criteria underwent CFD simulations using ANSYS Fluent Meshing (Canonsburg, PA) in which unstructured mesh models were generated to solve the standard dual equation turbulence model (k‐ω). Objective and supplemental descriptive measures were obtained and statistical analyses were performed with both parametric and non‐parametric tests to evaluate statistical significance at P <.05. Results: Regarding area and volumetric assessments, there were statistically significant mean differences in Total Volume and Minimum CSA between non‐OSA and OSA groups at inhalation and exhalation (P =.002,.003,.004, and.007), respectively. There were also statistically significant mean differences in volume and min CSA between the inhalation and exhalation for the non‐OSA group (P <.001 and.002), respectively. Conclusion: While analysis of the CFD simulation was limited by the collected data available, a finding consistent with published literature was that the OSA subject group simulation models depicted the point of lowest pressure coinciding with the area of maximum constriction. [ABSTRACT FROM AUTHOR]

Copyright of Revue d'Orthopédie Dento-Faciale is the property of Parresia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

BACKGROUND: X-ray cone-beam computed laminography (CL) is widely used for large flat objects that computed tomography (CT) cannot investigate. The rotation angle of axis tilt makes geometric correction of CL system more complicated and has more uncertain factors. Therefore, it is necessary to evaluate sensitivity of the geometric parameters of CL system in advance. OBJECTIVE: This study aims to objectively and comprehensively evaluate sensitivity of CL geometric parameters based on the projection trajectory. METHODS: This study proposes the Minimum Deviation Unit (MDU) to evaluate sensitivity of CL geometric parameters. First, the projection trajectory formulas are derived according to the spatial relationship of CL system geometric parameters. Next, the MDU of the geometric parameters is obtained based on the projection trajectories and used as the evaluation index to measure the sensitivity of parameters. Then, the influence of the rotation angle of the axis tilt and magnification on the MDU of the parameters is analyzed. RESULTS: At low magnification, three susceptible parameters (η, u0, v0) with MDU less than 1 (° or mm) must be calibrated accurately to avoid geometric artifacts. The sensitivity of CL parameters increases as the magnification increases, and all parameters become highly sensitive when the magnification power is greater than 10. CONCLUSION: The results of this study have important guiding significance for the subsequent further parameter calibration. [ABSTRACT FROM AUTHOR]

Intraoperative CT scanning is the international standard for treating midface fractures as it allows intraoperative assessment of reduction and fixation. To our knowledge, no NHS hospital in the UK has this facility yet due to the financial and logistical burden of its implementation. The aim of this study was to determine if complications including the requirement for a return to theatre (RTT) could have been predicted from the post-fixation CT scan. All treated midface fractures that had presented to a regionalised major trauma centre within two years (01 January 2020 - 31 December 2021) were identified. Those developing complications including RTT were determined. All postoperative CT scans (including those without complication or RTT) were re-analysed with the clinicians blinded to the outcomes to determine the positive predictive value (PPV) and negative predictive value (NPV) of requiring RTT to alter plate position intraoperatively based on CT scan alone. In all, there were eight episodes of unplanned return to theatre, resulting in an overall RTT rate of 8/119 (6.7%). When only analysing patients treated for orbital fractures this RTT rises to 8/40 (20%). Of those eight patients who had a postoperative CT and required RTT, this could have been predicted in 7/8 (87.5%). A total of 16/44 (36.4%) patients that did not have RTT would have additionally been recommended to have the plate position altered based on CT alone. Based upon those that had a CT, the PPV of CT alone being able to predict those requiring RTT was 40.6% and the NPV 96.2%. Our results would suggest intraoperative CT would likely have prevented eight patients requiring RTT in two years and could have improved outcomes in 16 cases. In preventing RTT as well as potentially improving the outcomes of a further 16 cases in maxillofacial surgery, the purchase of an intraoperative CT scanner could yield net savings of £75534-£114990 over two years. [ABSTRACT FROM AUTHOR]

Copyright of Operative Orthopädie und Traumatologie is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revue d'Orthopédie Dento-Faciale is the property of Parresia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Purpose: Ventilation-induced tumour motion remains a challenge for the accuracy of proton therapy treatments in lung patients. We investigated the feasibility of using a 4D virtual CT (4D-vCT) approach based on deformable image registration (DIR) and motion-aware 4D CBCT reconstruction (MA-ROOSTER) to enable accurate daily proton dose calculation using a gantry-mounted CBCT scanner tailored to proton therapy. Methods: Ventilation correlated data of 10 breathing phases were acquired from a porcine ex-vivo functional lung phantom using CT and CBCT. 4D-vCTs were generated by (1) DIR of the mid-position 4D-CT to the mid-position 4D-CBCT (reconstructed with the MA-ROOSTER) using a diffeomorphic Morphons algorithm and (2) subsequent propagation of the obtained mid-position vCT to the individual 4D-CBCT phases. Proton therapy treatment planning was performed to evaluate dose calculation accuracy of the 4D-vCTs. A robust treatment plan delivering a nominal dose of 60 Gy was generated on the average intensity image of the 4D-CT for an approximated internal target volume (ITV). Dose distributions were then recalculated on individual phases of the 4D-CT and the 4D-vCT based on the optimized plan.Dose accumulation was performed for 4D-vCT and 4D-CT using DIR of each phase to the mid position, which was chosen as reference. Dose based on the 4D-vCT was then evaluated against the dose calculated on 4D-CT both, phase-by-phase as well as accumulated, by comparing dose volume histogram (DVH) values (Dmean, D2%, D98%, D95%) for the ITV, and by a 3D-gamma index analysis (global, 3%/3 mm, 5 Gy, 20 Gy and 30 Gy dose thresholds). Results: Good agreement was found between the 4D-CT and 4D-vCT-based ITV-DVH curves. The relative differences ((CT-vCT)/CT) between accumulated values of ITV Dmean, D2%, D95% and D98% for the 4D-CT and 4D-vCT-based dose distributions were −0.2%, 0.0%, −0.1% and −0.1%, respectively. Phase specific values varied between −0.5% and 0.2%, −0.2% and 0.5%, −3.5% and 1.5%, and −5.7% and 2.3%. The relative difference of accumulated Dmean over the lungs was 2.3% and Dmean for the phases varied between −5.4% and 5.8%. The gamma pass-rates with 5 Gy, 20 Gy and 30 Gy thresholds for the accumulated doses were 96.7%, 99.6% and 99.9%, respectively. Phase-by-phase comparison yielded pass-rates between 86% and 97%, 88% and 98%, and 94% and 100%. Conclusions: Feasibility of the suggested 4D-vCT workflow using proton therapy specific imaging equipment was shown. Results indicate the potential of the method to be applied for daily 4D proton dose estimation.

Computer Tomography (CT) is a complicated imaging system, requiring highly geometric positioning. We found a special artifact caused by detection plane tilted around z-axis. In short scan cone-beam reconstruction, this kind of geometric deviation result in half circle shaped fuzzy around highlighted particles in reconstructed slices. This artifact is distinct near the slice periphery, but deficient around the slice center. We generated mathematical models, and InceptionV3-R deep network to study the slice artifact features to estimate the detector z-axis tilt angle. The testing results are: mean absolute error of 0.08819 degree, the Root mean square error of 0.15221 degree and R-square of 0.99944. A geometric deviation recover formula was deduced, which can eliminate this artifact efficiently. This research enlarges the CT artifact knowledge hierarchy, and verifies the capability of machine learning in CT geometric deviation artifact recoveries. [ABSTRACT FROM AUTHOR]

Periodontal Ehlers‐Danlos syndrome (pEDS) is a rare disorder caused by heterozygous mutations in complement 1 subunit genes C1R and C1S. To date, 148 cases have been described in the literature.We describe a case of a suspected de novo‐mutation of pEDS with generalized Periapical cemental dysplasia (PCD) and cerebral leukoencephalopathy. [ABSTRACT FROM AUTHOR]

Cone-Beam computed tomography (CBCT) has become the most important component of modern radiotherapy for positioning tumor patients directly before treatment. In this work we investigate alternations to standard acquisition protocol, called preset, for patients with a tumor in the thoracic region. The effects of the changed acquisition parameters on the image quality are evaluated using the Catphan Phantom and the image analysis software Smári. The weighted CT dose index (CTDIW) is determined in each case and the effects of the different acquisition protocols on the patient dose are classified accordingly. Additionally, the clinical suitability of alternative presets is tested by investigating correctness of image registration using the CIRS thorax phantom. The results show that a significant dose reduction can be achieved. It can be reduced by 51% for a full rotation by adjusting the gantry speed. A more patientspecific uptake protocol for patients with laterally located tumor was created which allows a dose reduction of 54%.

Rhinosinusitis is one of the most common pathologies affecting the paranasal sinuses and is basically subdivided into acute or chronic. The maxillary sinuses are the most affected and these are closely related to the roots of the posterosuperior teeth. It is of utmost importance that dentists have a perfect knowledge of the clinical and imaging aspects of this condition. Aiming at an emphatic direction for the use of computed tomography, more specifically cone beam computed tomography, a clinical case was discussed exposing the subjectivity of the symptomatology of this condition and the important role of this imaging examination in assertive diagnosis and, consequently, in a correct therapy.

Objective. High atomic number element nanoparticles have shown potential in tumor diagnosis and therapy. X-ray fluorescence computed tomography (XFCT) technology enables quantitative imaging of high atomic number elements by specifically detecting characteristic x-ray signals. The potential for further biomedical applications of XFCT depends on balancing sensitivity, spatial resolution, and imaging speed in existing XFCT imaging systems. Approach. In this study, we utilized a high-energy resolution pixelated photon-counting detector for XFCT imaging. We tackled degradation caused by multi-pixel events in the photon-counting detector through energy and interaction position corrections. Sensitivity and spatial resolution imaging experiments were conducted using PMMA phantoms to validate the effectiveness of the multi-pixel events correction algorithm. Main results. After correction, the system's sensitivity and spatial resolution have both improved. Furthermore, XFCT/CBCT dual-modality imaging of gadolinium nanoparticles within mice subcutaneous tumor was successfully achieved. Significance. These results demonstrate the preclinical research application potential of the XFCT/CBCT dual-modality imaging system in high atomic number nanoparticle-based tumor diagnosis and therapy., (© 2024 Institute of Physics and Engineering in Medicine. All rights, including for text and data mining, AI training, and similar technologies, are reserved.)

Ventilation-induced tumour motion remains a challenge for the accuracy of proton therapy treatments in lung patients. We investigated the feasibility of using a 4D virtual CT (4D-vCT) approach based on deformable image registration (DIR) and motion-aware 4D CBCT reconstruction (MA-ROOSTER) to enable accurate daily proton dose calculation using a gantry-mounted CBCT scanner tailored to proton therapy. Ventilation correlated data of 10 breathing phases were acquired from a porcine ex-vivo functional lung phantom using CT and CBCT. 4D-vCTs were generated by (1) DIR of the mid-position 4D-CT to the mid-position 4D-CBCT (reconstructed with the MA-ROOSTER) using a diffeomorphic Morphons algorithm and (2) subsequent propagation of the obtained mid-position vCT to the individual 4D-CBCT phases. Proton therapy treatment planning was performed to evaluate dose calculation accuracy of the 4D-vCTs. A robust treatment plan delivering a nominal dose of 60 Gy was generated on the average intensity image of the 4D-CT for an approximated internal target volume (ITV). Dose distributions were then recalculated on individual phases of the 4D-CT and the 4D-vCT based on the optimized plan. Dose accumulation was performed for 4D-vCT and 4D-CT using DIR of each phase to the mid position, which was chosen as reference. Dose based on the 4D-vCT was then evaluated against the dose calculated on 4D-CT both, phase-by-phase as well as accumulated, by comparing dose volume histogram (DVH) values (D mean , D 2% , D 98% , D 95%) for the ITV, and by a 3D-gamma index analysis (global, 3%/3 mm, 5 Gy, 20 Gy and 30 Gy dose thresholds). Good agreement was found between the 4D-CT and 4D-vCT-based ITV-DVH curves. The relative differences ((CT-vCT)/CT) between accumulated values of ITV D mean , D 2% , D 95% and D 98% for the 4D-CT and 4D-vCT-based dose distributions were −0.2%, 0.0%, −0.1% and −0.1%, respectively. Phase specific values varied between −0.5% and 0.2%, −0.2% and 0.5%, −3.5% and 1.5%, and −5.7% and 2.3%. The relative difference of accumulated D mean over the lungs was 2.3% and D mean for the phases varied between −5.4% and 5.8%. The gamma pass-rates with 5 Gy, 20 Gy and 30 Gy thresholds for the accumulated doses were 96.7%, 99.6% and 99.9%, respectively. Phase-by-phase comparison yielded pass-rates between 86% and 97%, 88% and 98%, and 94% and 100%. Feasibility of the suggested 4D-vCT workflow using proton therapy specific imaging equipment was shown. Results indicate the potential of the method to be applied for daily 4D proton dose estimation. [ABSTRACT FROM AUTHOR]

Abstract Trauma to the facial area accounts for a significant number of admissions to the emergency department. Diagnostic imaging is almost always required, and is critical in determining patient management. Multi‐detector computed tomography (MDCT) appears consistently in the literature as the gold‐standard imaging modality for facial bones, but results in a high radiation dose to the patient. This makes the application and advancement of dose reduction and dose optimisation methods vital. This narrative review presents a critical analysis of the literature concerning diagnostic imaging of facial bone trauma, with an emphasis on dose reduction methods for MDCT. Databases including Pubmed, Medline, Web of Science and Scopus were used to investigate this topic, with the key words: facial bone trauma, computed tomography (CT) imaging and dose reduction. Exclusion criteria included studies on nasal bone fracturing, dental imaging, elective surgeries and paediatric imaging. The literature shows overwhelming support for MDCT, given its accuracy, efficiency and ease of operation. Noise reducing reconstruction algorithms show promise as a successful method of dose reduction in facial bone imaging. Investigations of more innovative techniques also appear within the literature, including diagnostic cone‐beam CT (CBCT), intraoperative CBCT and dual‐source CT (DSCT), but further research is required to confirm their clinical value.

Introduction: Studies on software accuracy of reformatted panoramic computed tomography (CT) images are scarce. Objectives: The aim of this study was to evaluate the software accuracy of reformatted panoramic views from cone-beam computed tomography (CBCT). Methods: Ten dry mandibles were scanned using CBCT with different voxel sizes. Following the reconstruction of panoramic views with three different software, horizontal and vertical linear measurements were performed using the electronic rules of each software. Measurements of the corresponding dry mandibles were taken with a digital caliper and defined as the gold standard. Results: There were no statistically significant differences in linear distances among the dry mandibles and reformatted panoramic CT views. The relative error ranged from 1.3 to 8.0%, depending on the software and voxel size. Conclusions: The linear measurements on reformatted panoramic views are reliable. [ABSTRACT FROM AUTHOR]

Cone-beam computed tomography (CBCT) machines produce relatively low levels of harmful ionizing radiation, as compared with the computed tomography devices used in medical practices. The Carestream CS9600 CBCT imaging device has been recently introduced into the marketplace, and the manufacturer reports the use of an increased x-ray tube voltage (120 kVp) for the device, along with a reduced patient dose that is achieved using added filtration. Independent dosimetry studies are performed to ensure appropriate radiation exposure dose levels are within recommended safety guidelines.The purpose of this study is to independently evaluate and measure the radiation exposure dose performance parameters of the CS9600 CBCT, including its multiple field of view, exposure settings, and filtration options. A thimble ionization chamber and PMMA phantom were used to characterize dose index using the established SEDENTEXTCT evaluation method. The phantom-obtained radiation dose index measures ranged from 0.128782–13.848 milligrays (mGy) for the various scanning options evaluated. The field of view, type of filter used, and phantom size all had a direct impact on the relationship between the experimentally obtained dose index measures and the dose area product values reported by the manufacturer. A strong linear correlation was observed between the experimentally obtained dose index measures and the manufacturer-reported dose area product values. The 0.7 mm Cu filter that has been added to the CS9600 reduced the exposure dose index measures even with the x-ray tube kilovoltage peak (kVp) being increased to 120 kVp, as compared with the 0.15 mm Cu filter at 90 kVp. [ABSTRACT FROM AUTHOR]

With steadily increasing use in dimensional metrology applications, especially for delicate parts and those with complex internal features, X-ray computed tomography (XCT) has transitioned from a medical imaging tool to an inspection tool in industrial metrology. This has resulted in the demand for standardized test procedures and performance evaluation standards to enable reliable comparison of different instruments and support claims of metrological traceability. To meet these emerging needs, the American Society of Mechanical Engineers (ASME) recently released the B89.4.23 standard for performance evaluation of XCT systems. There are also ongoing efforts within the International Organization for Standardization (ISO) to develop performance evaluation documentary standards that would allow users to compare measurement performance across instruments and verify manufacturer's performance specifications. Designing these documentary standards involves identifying test procedures that are sensitive to known error sources. This paper, which is the third in a series, focuses on geometric errors associated with the detector and rotation stage of XCT instruments. Part I recommended positions of spheres in the measurement volume such that the sphere center-to-center distance error and sphere form errors are sensitive to the detector geometry errors. Part II reported similar studies on the errors associated with the rotation stage. The studies in Parts I and II only considered one position of the rotation stage and detector; i.e., the studies were conducted for a fixed measurement volume. Here, we extend these studies to include varying positions of the detector and rotation stage to study the effect of magnification. We report on the optimal placement of the stage and detector that can bring about the highest sensitivity to each error. [ABSTRACT FROM AUTHOR]

In recent years the development of cone-beam reconstruction algorithms has been an active research area in x-ray computed tomography (CT), and significant progress has been made in the advancement of algorithms. Theoretically exact and computationally efficient analytical algorithms can be found in the literature. However, in single photon emission computed tomography (SPECT), published cone-beam reconstruction algorithms are either approximate or involve iterative methods. The SPECT reconstruction problem is more complicated due to degradations in the imaging detection process, one of which is the effect of attenuation of gamma ray photons. Attenuation should be compensated for to obtain quantitative results. In this paper, an analytical reconstruction algorithm for uniformly attenuated cone-beam projection data is presented for SPECT imaging. The algorithm adopts the DBH method, a procedure consisting of differentiation and backprojection followed by a finite inverse cosh-weighted Hilbert transform. The significance of the proposed approach is that a selected region of interest can be reconstructed even with a detector with a reduced field of view. The algorithm is designed for a general trajectory. However, to validate the algorithm, a numerical study was performed using a helical trajectory. The implementation is efficient and the simulation result is promising.

The Prompt Gamma-ray Activation Imaging and Neutron Tomography (PGAI-NT) instrument at the PGAA facility of the Heinz Maier-Leibnitz Center (MLZ), provides a method to obtain and effectively visualize position-sensitive element abundances in samples by combining a three-dimensional extension of Prompt Gamma-ray Activation Analysis (PGAA) and Neutron Tomography (NT). Inspired by a proof-of-principle study, a cone-beam tomography set-up was designed, tested and installed. This article reports on the design of the new cone-beam tomography set-up and its optimization using neutron beam simulations and physical measurements. A new position-sensitive neutron detector with improved performance and instrument environment integration was designed, built and tested. The overall NT performance of the set-up is investigated in the course of a Quality Assessment for neutron tomography sites. Its stand-alone NT and all-in-one PGAI-NT suitability is determined. [ABSTRACT FROM AUTHOR]

The development of standards for evaluating the performance of X-ray computed tomography (XCT) instruments is ongoing within the American Society of Mechanical Engineers (ASME) and the International Organization for Standardization (ISO) working committees. A key challenge in developing documentary standards is to identify test procedures that are sensitive to known error sources. In Part I of this work, we described the effect of geometry errors associated with the detector and determined their influence through simulations on sphere center-to-center distance errors and sphere form errors for spheres located in the tomographically reconstructed measurement volume. We also introduced a new simulation method, the single-point ray tracing method, to efficiently perform the distance and form error computations and presented data validating the method. In this second part, also based on simulation studies, we describe the effect of errors associated with the rotation stage on sphere center-to-center distance errors and sphere form errors for spheres located in the tomographically reconstructed measurement volume. We recommend optimal sphere center locations that are most sensitive to rotation stage errors for consideration by documentary standards committees in the development of test procedures for performance evaluation. [ABSTRACT FROM AUTHOR]

X-ray computed tomography (XCT), long used in medical imaging and defect inspection, is now increasingly used for dimensional measurements of geometrical features in engineering components. With widespread use of XCT instruments, there is growing need for the development of standardized test procedures to verify manufacturer specifications and provide pathways to establish metrological traceability. As technical committees within the American Society of Mechanical Engineers (ASME) and the International Organization for Standardization (ISO) are developing documentary standards that include test procedures that are sensitive to all known error sources, we report on work exploring one set of error sources, instrument geometry errors, and their effect on dimensional measurements. In particular, we studied detector and rotation stage errors in cone-beam XCT instruments and determined their influence on sphere center-to-center distance errors and sphere form errors for spheres located in the tomographically reconstructed measurement volume. We developed a novel method, called the single-point ray tracing method, that allows for efficient determination of the sphere center-to-center distance error and sphere form error in the presence of each of the different geometry errors in an XCT instrument. In Part I of this work, we (1) describe the single-point ray tracing method, (2) discuss optimal placement of spheres so that sphere center-to-center distance errors and sphere form errors are sensitive to the different detector geometry errors, and (3) present data validating our method against the more conventional radiograph-based tomographic reconstruction method. In Part II of this work, we discuss optimal placement of spheres so that sphere center-to-center distance errors and sphere form errors are sensitive to error sources associated with the rotation stage. This work is in support of ongoing standards development activity within ASME and ISO for XCT performance evaluation. [ABSTRACT FROM AUTHOR]

Trauma to the facial area accounts for a significant number of admissions to the emergency department. Diagnostic imaging is almost always required, and is critical in determining patient management. Multi‐detector computed tomography (MDCT) appears consistently in the literature as the gold‐standard imaging modality for facial bones, but results in a high radiation dose to the patient. This makes the application and advancement of dose reduction and dose optimisation methods vital. This narrative review presents a critical analysis of the literature concerning diagnostic imaging of facial bone trauma, with an emphasis on dose reduction methods for MDCT. Databases including Pubmed, Medline, Web of Science and Scopus were used to investigate this topic, with the key words: facial bone trauma, computed tomography (CT) imaging and dose reduction. Exclusion criteria included studies on nasal bone fracturing, dental imaging, elective surgeries and paediatric imaging. The literature shows overwhelming support for MDCT, given its accuracy, efficiency and ease of operation. Noise reducing reconstruction algorithms show promise as a successful method of dose reduction in facial bone imaging. Investigations of more innovative techniques also appear within the literature, including diagnostic cone‐beam CT (CBCT), intraoperative CBCT and dual‐source CT (DSCT), but further research is required to confirm their clinical value. [ABSTRACT FROM AUTHOR]

Abstract Introduction The anterior ethmoidal artery (AEA) is one of the main arteries that supply both the nasal mucosa and the ethmoid sinuses. The AEA shows variability regarding its distance from adjacent structures. Several studies have developed techniques to identify the AEA. Objective This study aimed to compare the measurements from the AEA to the ethmoid bulla and to the frontal beak by using computed tomography of the face, while identifying their intraindividual and interindividual variations. Methods We analyzed 300 CT scans of the face performed at the CT scan Center at Hospital. The average age of subjects was 36 ± 15.1 years (range 4–84). Results We found that the average distance from the AEA to the ethmoid bulla was 17.2 ± 1.8 mm and the distance from the AEA to the frontal beak was 15.1 ± 2.2 mm. Regarding the average distance from the AEA to the frontal beak (AEA-frontal beak), there was a difference between the right and left sides, with the former being 0.4 mm higher on average than the latter. Among the age groups, there was a significant difference of distances between the AEA and the ethmoid bulla (AEA-ethmoid bulla), which were shorter in the ≤ 12 years group. There was a positive and significant correlation between both measurements analyzed, with low values (high) of AEA-ethmoid bulla distance corresponding to low values (high) of AEA-frontal beak distance. Conclusion The measurements obtained adds anatomical knowledge that can serve as a parameter in frontal and ethmoid sinus surgery.

Objective To execute geometric calibration and calibration phantom design to realize high-quality cone-beam Micro -CT image reconstruction. Methods The geometrical position parameters of cone -beam Micro -CT system were deduced by the data of the designed phantom projected on the detector by means of linear fitting and geometric relation, so as to realize the geometric calibration of the system. The calculation software and the simulation experiment were achieved by VC++ programming language. Results The validity and feasibility of the calibration model and method were proved by the experimental simulation. Conclusfon The geometric calibration method can accurately calculate the geometrical position parameter errors ofthe cone-beam Micro-CT system. It can effectively reduce the artifacts in the reconstructed image and further improve the imaging resolution by adjusting the geometric position parameters. [ABSTRACT FROM AUTHOR]

The aim of this study was to compare the bone density of bone defects treated with lyophilizated amniotic membrane (LAM) and collagen Membrane (CM), at 3 and 5 weeks. Two bone defects of 4mm in diameter and 6mm deep were created in left distal femoral diaphysis of New Zealand rabbits (n=12). The animals were randomly divided into 2 groups. One of the defects was covered with lyophilized amniotic membrane (Rosa Chambergo Tissue Bank/National Institute of Child Health-IPEN, Lima, Peru) or collagen Membrane (Dentium Co, Seoul, Korea). The second was left uncovered (NC). The rabbits were killed after 3 and 5 weeks (3 rabbits/period). The results showed a high bone density and repair of the defect by new bone. The tomographic study revealed that the bone density of the defects treated with LAM at 3 weeks was equivalent to the density obtained with CM and higher density compared with NC (p0.05). The results show that lyophilizated amniotic membrane provides bone density equal or higher to the collagen membrane.

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Introduction: The anterior ethmoidal artery (AEA) is one of the main arteries that supply both the nasal mucosa and the ethmoid sinuses. The AEA shows variability regarding its distance from adjacent structures. Several studies have developed techniques to identify the AEA. Objective: This study aimed to compare the measurements from the AEA to the ethmoid bulla and to the frontal beak by using computed tomography of the face, while identifying their intraindividual and interindividual variations. Methods: We analyzed 300 CT scans of the face performed at the CT scan Center at Hospital. The average age of subjects was 36 ± 15.1 years (range 4-84). Results: We found that the average distance from the AEA to the ethmoid bulla was 17.2 ± 1.8 mm and the distance from the AEA to the frontal beak was 15.1 ± 2.2 mm. Regarding the average distance from the AEA to the frontal beak (AEA-frontal beak), there was a difference between the right and left sides, with the former being 0.4 mm higher on average than the latter. Among the age groups, there was a significant difference of distances between the AEA and the ethmoid bulla (AEA-ethmoid bulla), which were shorter in the ≤ 12 years group. There was a positive and significant correlation between both measurements analyzed, with low values (high) of AEAethmoid bulla distance corresponding to low values (high) of AEA-frontal beak distance. Conclusion: Themeasurements obtained adds anatomical knowledge that can serve as a parameter in frontal and ethmoid sinus surgery. [ABSTRACT FROM AUTHOR]

• Two types of heterotopic mineralization were characterized by CT and MRI systems. • Cone-beam CT was similar to fan-beam CT in identifying heterotopic mineralization. • MRI identified osseous/soft tissue injury associated with heterotopic mineralization. • Suspensory ligament injuries were consistently found adjacent to mineralization's. • Ligament injuries were consistently found adjacent to proximal sesamoid avulsions. Heterotopic mineralization in equine distal limbs has been considered an incidental finding and little is known about its imaging features. The study aimed to identify heterotopic mineralization and adjacent pathology in the fetlock region with cone-beam (CB) computed tomography (CT), fan-beam (FB) CT, and low-field magnetic resonance imaging (MRI). Images from 12 equine cadaver limbs were examined for heterotopic mineralization and adjacent pathology and verified by macro-examination. Retrospective review of the CBCT/MR images from 2 standing horses was also included. CBCT and FBCT identified twelve mineralization's with homogeneous hyperattenuation: oblique-sesamoidean-ligament (5) without macroscopic abnormality; deep-digital-flexor-tendon (1) and suspensory-branch (6) with macroscopic abnormalities. MRI failed to identify all mineralization's, but detected suspensory branch splitting, and T2 and STIR hyperintensity in 4 suspensory-branches and 3 oblique-sesamoidean-ligaments. Macro-examination found corresponding disruption/splitting and discoloration. All modalities identified 7 ossified fragments showing cortical/trabecular pattern: capsular (1), palmar sagittal ridge (1), proximal phalanx (2) without macroscopic abnormality, and proximal sesamoid bones (3). On MRI, fragments were most identifiable on T1 images. All abaxial avulsions had suspensory-branch splitting on T1 images with T2 and STIR hyperintensity. Macro-examination showed ligament disruption/splitting and discoloration. Suspensory-branch/intersesamoidean ligament mineralization's were identified by CBCT in standing cases; 1 had associated T2 hyperintensity. Both CT systems were generally superior in identifying heterotopic mineralization's than MRI, while MRI provided information on soft tissue pathology related to the lesions, which may be important for management. [ABSTRACT FROM AUTHOR]

Long-object problem and short-object problem both deal with reconstruction problems with truncated conebeam CT projections acquired with a helical path. They have significantly less practical limitations than original exact cone-beam CT reconstruction algorithms which the cone-beam must cover the whole object. The short-object problem can be defined as reconstruction of the whole object having a finite support in the axial direction with helical scan extends a little bit above and below the object's support. However the longobject problem is to reconstruct the central region of interest (ROI) of a long object having an infinite support in the axial direction with helical scan extends a little a bit above and below the ROI. Although the short-object problem is more difficult to solve than the conventional exact reconstruction with non-truncated projections, the long-object problem presents greater challenge to researchers. Recently, with the great development of panel detector technology and computer technology, more and more researchers have been inspired to work on it. Because of great practical value of long-object algorithms, this paper focuses on the review and discussion of recent developments in long-object algorithms. All Long-object algorithms are classified as exact and approximate algorithms. After going briefly over the history of cone-beam algorithms, some novel cone-beam long-object algorithms are introduced, such as: Tam's algorithm, PImethod, PHI-method, etc. Then, the methods described are being compared and discussed.

The Precision of geometric parameters is the key requirement for grating-based phase-contrast CT and attenuationbased CT in cone-beam geometry. By extending our fan-beam geometric calibration work via Locally Linear Embedding (LLE) into the cone-beam case, here we calibrate the geometric parameters of our in-house phase-contrast CT system with attenuation projection data. Numerical and experimental studies show that the LLE-based calibration method is feasible to calibrate 8 parameters of the cone-beam geometry that improves reconstruction quality significantly. [ABSTRACT FROM AUTHOR]

X-ray computed tomography is an established volume imaging technique used routinely in medical diagnosis, industrial non-destructive testing, and a wide range of scientific fields. Traditionally, computed tomography uses scanning geometries with a single axis of rotation together with reconstruction algorithms specifically designed for this setup. Recently there has however been increasing interest in more complex scanning geometries. These include so called X-ray computed laminography systems capable of imaging specimens with large lateral dimensions or large aspect ratios, neither of which are well suited to conventional CT scanning procedures. Developments throughout this field have thus been rapid, including the introduction of novel system trajectories, the application and refinement of various reconstruction methods, and the use of recently developed computational hardware and software techniques to accelerate reconstruction times. Here we examine the advances made in the last several years and consider their impact on the state of the art. [ABSTRACT FROM AUTHOR]

BACKGROUND: Limited-angle problem occurs in many applications of X-ray computed tomography (CT) and it will lead to artifacts. OBJECTIVE: In this paper, we present the tomographic imaging of pipeline which is in service by cone-beam computed tomography (CBCT). And our purpose is to suppress the artifacts caused by the limited-angle problem. METHODS: First, traditional helical scanning strategy is adopted for the pipeline where can be fully scanned, and the slices with less or no defects from the reconstructed image are selected to constitute the prior image. Then a limited-angle reverse helical scanning strategy is developed for the pipeline where can be scanned within limited angular range. Second, considering the constraint of the prior image and the resemblance among slices of pipeline, an image model which incorporates the Schatten p(0 < p < 1)-norm penalty term is developed. Finally, split Bregman algorithm based method is utilized to solve the model. RESULTS: Numerical results show that our method is efficient and feasible in suppressing artifacts and it is superior to popular methods when the angular range is small. CONCLUSION: The developed method is promising in suppressing the artifacts in limited-angle problems, and it can be potentially used in pipeline testing. [ABSTRACT FROM AUTHOR]

The cone-beam reconstruction theory has been proposed by Kirillov in 1961, Tuy in 1983, Feldkamp in 1984, Smith in 1985, Pierre Grangeat in 1990. The Fourier slice theorem is proposed by Bracewell 1956, which leads to the Fourier image reconstruction method for parallel-beam geometry. The Fourier slice theorem is extended to fan-beam geometry by Zhao in 1993 and 1995. By combining the above mentioned cone-beam image reconstruction theory and the above mentioned Fourier slice theory of fan-beam geometry, the Fourier slice theorem in cone-beam geometry is proposed by Zhao 1995 in short conference publication. This article offers the details of the derivation and implementation of this Fourier slice theorem for cone-beam geometry. Especially the problem of the reconstruction from Fourier domain has been overcome, which is that the value of in the origin of Fourier space is 0/0. The 0/0 type of limit is proper handled. As examples, the implementation results for the single circle and two perpendicular circle source orbits are shown. In the cone-beam reconstruction if a interpolation process is considered, the number of the calculations for the generalized Fourier slice theorem algorithm is O(N^4), which is close to the filtered back-projection method, here N is the image size of 1-dimension. However the interpolation process can be avoid, in that case the number of the calculations is O(N^5). [ABSTRACT FROM AUTHOR]

Objective. X-ray fluorescence computed tomography (XFCT) is a promising noninvasive technique for in vivo imaging of high-Z elements (e.g. gadolinium (Gd) or gold (Au)). In this study we upgraded our experimental XFCT system using a flat panel photon counting detector with redesigned pinhole collimation in order to achieve 3D XFCT images during one scan. Approach. Aiming at the characteristics of pinhole-collimated cone-beam XFCT imaging, a new scatter correction algorithm was proposed to estimate the normalized spectrum of scatter background based on K-N formula and realize correction by a weighted least squares method. Then, images were quantitatively reconstructed by a maximum likelihood iterative algorithm with the attenuation correction. Main results. The potential on full-field in vivo XFCT imaging of this new system was investigated. An imaging experiment of a PMMA phantom with the diameter of 35 mm was carried out for quantitative evaluation of the system performance. Results show that 2 mg ml -1 Gd solutions can be successfully reconstructed with a 45 min cone-beam XFCT scan. In vivo XFCT imaging experiments of mice with injection of Gd nanoparticles (GdNPs) were also performed and demonstrated in this paper. A mouse was injected through the tail vein with 20 mg ml -1 NaGdF4 solution and then anesthetized with isoflurane during the cone-beam XFCT scan. Significance. The distribution of the GdNPs inside the mouse can be well reconstructed so that the deposition of NPs in vivo can be clearly observed, which indicates the feasibility of the proposed system for full-field XFCT of small animals and further potential in relevant in vivo research., (Creative Commons Attribution license.)