3D Cone-beam Computed Tomography Research Articles

Dynamic CBCT imaging using prior model-free spatiotemporal implicit neural representation (PMF-STINR)

Objective. Dynamic cone-beam computed tomography (CBCT) can capture high-spatial-resolution, time-varying images for motion monitoring, patient setup, and adaptive planning of radiotherapy. However, dynamic CBCT reconstruction is an extremely ill-posed spatiotemporal inverse problem, as each CBCT volume in the dynamic sequence is only captured by one or a few x-ray projections, due to the slow gantry rotation speed and the fast anatomical motion (e.g. breathing). Approach. We developed a machine learning-based technique, prior-model-free spatiotemporal implicit neural representation (PMF-STINR), to reconstruct dynamic CBCTs from sequentially acquired x-ray projections. PMF-STINR employs a joint image reconstruction and registration approach to address the under-sampling challenge, enabling dynamic CBCT reconstruction from singular x-ray projections. Specifically, PMF-STINR uses spatial implicit neural representations to reconstruct a reference CBCT volume, and it applies temporal INR to represent the intra-scan dynamic motion of the reference CBCT to yield dynamic CBCTs. PMF-STINR couples the temporal INR with a learning-based B-spline motion model to capture time-varying deformable motion during the reconstruction. Compared with the previous methods, the spatial INR, the temporal INR, and the B-spline model of PMF-STINR are all learned on the fly during reconstruction in a one-shot fashion, without using any patient-specific prior knowledge or motion sorting/binning. Main results. PMF-STINR was evaluated via digital phantom simulations, physical phantom measurements, and a multi-institutional patient dataset featuring various imaging protocols (half-fan/full-fan, full sampling/sparse sampling, different energy and mAs settings, etc). The results showed that the one-shot learning-based PMF-STINR can accurately and robustly reconstruct dynamic CBCTs and capture highly irregular motion with high temporal (∼ 0.1 s) resolution and sub-millimeter accuracy. Significance. PMF-STINR can reconstruct dynamic CBCTs and solve the intra-scan motion from conventional 3D CBCT scans without using any prior anatomical/motion model or motion sorting/binning. It can be a promising tool for motion management by offering richer motion information than traditional 4D-CBCTs.

Comparison of 3D Easy Box cone-beam computed tomography analysis with 2D Modified Easy Box on OPG as a prognostic tool for impacted maxillary canines: A pilot study.

To assess and compare the validity of 2D modified Easy Box and measurement of the Beta angle on standard conventional orthopantomogram (OPG) versus 3D cone-beam computed tomography (CBCT) OPG-constructed view. A retrospective agreement study. The aim of this study was to construct an Easy Box on a standard conventional OPG and to validate this novel method by comparing it with the Easy Box method on 3D CBCT. After approval from the Ethics Committee, OPG and CBCT radiographs were obtained for the study from departmental records and five private practices in the same location (Indore, India). The radiographs were selected based on record availability and with written consent from the participants before the commencement of the study. The records were analysed to enable a comparison and to assess the accuracy of Easy Box construction on both 3D CBCT and standard conventional OPG radiographs. The location of the impacted canine within the Easy Box boundaries and the measurement of the Beta angle were determined on both views. A perfect agreement was obtained for the comparison of 3D Easy Box CBCT analysis with 2D modified Easy Box on OPG for impacted maxillary canines (Kappa = 1.0). A Bland-Altman (LoA) analysis showed no proportional bias in the comparison of the Beta angle on 3D and 2D OPG radiographs. Beta angle and 2D modified Easy Box on a conventional OPG yield similar results when compared to Easy Box on 3D CBCT OPG-constructed view. The standard OPG was valuable and cost-effective, particularly in the early stages of diagnosis and treatment planning, either as a substitute or when CBCT was unavailable.

Assessing the Accuracy of Lateral Cephalogram in Quantifying Three-Dimensional Pharyngeal Airway Morphology Compared to Cone-Beam Computed Tomography.

When it comes to orthodontic diagnosis and treatment planning, the structures of the upper and lower airway spaceare crucial because of therole they play in craniofacial development. The major objective of this study was to evaluate the accuracy of lateral cephalogram in the evaluation of upper and lower pharyngeal space by comparing it to clinical usage of cone-beam computed tomography (CBCT) in quantifying the 3D morphology of the pharyngeal airway. In total, 70 patients were included in the study. They had both a CBCT scan and a lateral cephalogram performed within a week of each other. Different cephalometric landmarks have been utilized to estimate linear and area dimensions for use in lateral cephalogram airway investigations. By superimposing the lateral cephalogram measurement of the vertical height of the pharyngeal airwayover axial CBCT slices of 0.8 to 1 mm in thickness, airway volumes were calculated. For this study, we measured the pharyngeal airway space in each patient in two dimensions (2D) using the airway area from the lateral cephalogram and in three dimensions (3D) using the airway volume from the CBCT scan over the same region of interest, using a uniform scale and magnification throughout all split 3D volumes. The mean value of the area of pharyngeal space calculated by lateral cephalograph analysis (LCA) was 336.35 ± 86.49 mm2. The maximum value was 551.234 mm2. The minimum value was 206.32 mm2. The mean value of the volume of the same area calculated using CBCT was 3409.11 ± 1237.96 mm3. The maximum value was 5887.23 mm3. When the area calculated using LCA was compared with the volume calculated using CBCT, the correlation between them was significant statistically(r=0.831, p-value =0.000). The mean values of volume evaluated in 3D CBCT in males were 4198±1008 mm3 while for females it was 2980±1134.5 mm3. During the statistical analysis,these observations were found to have a positive correlation with increased volume of pharyngeal space in males as compared to that of females (p=0.006). The values of the area of pharyngeal space calculated using LCA in males was 370.1±60.9 mm2. while it was 301.9±88 mm2 in females. The area estimated for the pharyngeal airway on LCA correlates strongly with the volume determined by a CBCT scan. Since we have considered pharyngeal space analysis using CBCT to be a reliable and standard methodology, therefore a positive correlation of area calculated using LCA with volume calculated using CBCT shows that the analysis made by LCA can be reliable.

Biomedical Application of CT Assisted CBCT 3D Imaging Technology in Oral Implantation

In the field of oral implantology, our goals were to investigate the diagnostic utility of traditional CT imaging technology and 3D CBCT imaging technology based on the Internet of Things (IoT) dental Computed Tomography assisted CBCT, as well as to compare and contrast their respective advantages. 72 patients were split evenly between two groups: a control group with 35 participants and a study group with 37 participants. (1) Surgical indexes: The operation time of the control group was (27.96+4.64) minutes and (14.08+3.14) minutes, and the intraoperative blood loss was (16.36+2.95) ml and (5.85+0.64) ml, respectively. The time it took to do the procedure in the experimental group was (14.08+3.14) minutes. In the group that was under examination, both the total amount of time spent operating and the amount of blood lost during the procedure were significantly lower (P <0.05). (2) Dental function: There were no statistically significant variations in dental beauty, comfort, chewing, or retention between the two groups before surgery (P >0.05). This was determined by comparing the results of the dental examinations. After surgery, the dental function of the research group was significantly greater than that of the control group, and the difference between the two groups was statistically significant (P <0.05). (3) Theraputic effect: the effective rate of the treatment in the control group was 85.71 percent, while the effective rate in the study group was 94.59%. (4) Quality of life: when compared with the control group, the comprehensive quality of life of physiological, social, emotional, and cognitive functions in the research group was higher, and the difference was statistically significant (P < 0.05); (5) Satisfaction: the control group’s level of satisfaction was 80.00%, while the study group’s level of satisfaction was 94.59%. (6) Cost: the cost of the treatment in the research group was significantly lower than the cost of the treatment in the control group. As a result, the dental computed tomography assisted cone beam computed tomography (CBCT) 3D imaging technology based on the internet of things should be considered for implementation.

Mandibular canine development as an indicator of maxillary cleft site canine development

Objectives: The objective of this study was to determine if mandibular canine development is an indicator of maxillary cleft site canine development. Material and Methods: A cross-sectional chart review with analysis of cone-beam computed tomography (CBCT) imaging of patients aged 7–12 with a unilateral complete cleft lip and palate who received alveolar bone graft surgery from January 2009 to January 2019. Three-dimensional (3D) measurements of the cleft site canine and ipsilateral mandibular canine were taken. A two-dimensional image was created from the 3D CBCT to simulate a traditional panoramic radiograph. Descriptive statistics and multivariable linear regression analyses were conducted, adjusting for age and gender. Pearson and Spearman correlations were calculated. The main outcome measure was the mandibular canine crown-to-root ratio (C:RR) compared to that of the maxillary cleft site canine C:RR. Results: Five hundred and thirteen patients were reviewed, of which 78 met the inclusion criteria. Adjusting for age and gender, every unit change in mandibular canine C:RR corresponds to 0.69 (95% confidence interval [CI] = 0.42–0.95) change in maxillary canine C:RR, up to a mandibular canine C:RR of 3. Beyond a mandibular C:RR of 3, no change in the maxillary canine C:RR was observed (−0.02; 95%CI = −0.27–0.24). Pearson correlation coefficient was r = 0.65, and the Spearman correlation was P = 0.75. Conclusion: Mandibular canine C:RR is correlated to maxillary cleft site canine C:RR when the mandibular canine C:RR is ≤3.

3D wrist imaging - Is it time for superman to retire?

Computed tomography (CT) of the wrist may be challenged, due to patients' inability to extend the arm for a "Superman pose" resulting in increased radiation dose due to scatter. Alternative positions and less dose administering modalities such as 3D Cone-beam CT (CBCT) and single-shot CT could be considered. This phantom study aimed to estimate scatter radiation dose in different phantom positions using helical and single-shot CT and 3D CBCT. Wireless electronic dosimeters attached to the head and chest of an anthropomorphic phantom in various clinically relevant positions were used to measure scatter radiation. In helical CT, the following positions were used: Superman pose, semi-superman pose, wrist on the abdomen, and single-shot CT with the patient sitting in front of and behind the gantry. In 3D CBCT, the phantom was in a supine position with the arm extended laterally. Helical CT using the Superman pose resulted in a total scattered radiation dose of 64.8 µGy. The highest total dose (269.7 µGy) was obtained with the wrist positioned on the abdomen while the lowest total dose was achieved in single-shot CT with the phantom sitting behind the gantry with the forearm placed inside the gantry (3.2 µGy). The total dose in 3D CBCT was 171.1 µGy. The commonly used semi-superman and wrist-on-abdomen positions in CT administer the highest scattered doses and should be avoided when either single-shot CT or 3D CBCT is available. Radiographers should carefully consider alternatives when a patient referred for wrist CT cannot comply with the Superman position.

Three-dimensional assessment of periodontal support of lower incisors for skeletal Class II malocclusion undergoing presurgical orthodontic treatment with different vertical skeletal patterns

BackgroundThe aim of the present study was to compare periodontal support changes during retraction of mandibular anterior teeth for skeletal Class II malocclusion with different facial divergence and to analyze relevant factors influencing bone remodeling by applying three-dimensional (3D) cone-beam computed tomography (CBCT) reconstruction technology.MethodsForty-eight patients with Class II malocclusion requiring surgical orthodontic treatment enrolled in the study were divided into the hyperdivergent group (n = 16), normodivergent group (n = 16) and hypodivergent group (n = 16) according to their vertical skeletal patterns. Cone-beam computed tomography (CBCT) scans were obtained before treatment (T1) and after presurgical orthodontic treatment (T2). The two-dimensional (2D) alveolar bone morphology, movement of mandibular central incisors and volume of the alveolar bone around incisors were measured on the labial and lingual sides by 3D CBCT reconstruction technology. Statistical analyses were performed with one-way ANOVA, paired t tests and multiple linear regression.ResultsDuring presurgical orthodontic treatment, the alveolar bone height on the labial side of the hyperdivergent group decreased significantly (P ≤ 0.05), but was maintained in the normodivergent and hypodivergent groups (P > 0.05). However, the alveolar bone volume, alveolar bone thickness at each level and alveolar bone height on the lingual side decreased significantly for all the groups. Apart from the initial morphometric measurements at T1, the morphology of lingual alveolar bone at T2 was significantly influenced by the direction and amount of tooth movement. Horizontal retraction and vertical protrusion of the root apex were negatively related to the alveolar bone on the lingual side after presurgical orthodontic treatment.ConclusionFor Class II malocclusion patients undergoing presurgical orthodontic treatment, the changes in the periodontal support of the lower central incisors varied in different vertical skeletal patterns. There exists a great periodontal risk of alveolar bone resorption on the lingual side for various vertical types. To avoid alveolar bone deterioration, it is essential to investigate the bone remodeling of patients with different alveolar bone conditions and cautiously plan tooth movement prior to orthodontic treatment. Moreover, 3D measurements based on CBCT construction can provide complementary information to traditional 2D measurements.

Skeletal and Dentoalveolar Changes in Growing Patients Treated with Rapid Maxillary Expansion Measured in 3D Cone-Beam Computed Tomography.

The skeletal and dental effects of rapid maxillary expansion (RME) have been extensively studied, but high-quality research is still needed to determine the three-dimensional (3D) effects of RME. The aim of this study was to compare skeletal and dentoalveolar parameters through cone-beam computed tomography (CBCT) pre- (T1) and post-treatment (T2) with respect to RME. Twenty growing patients (mean age 10.7 years) were treated with a Hyrax-type expander. A 3D CBCT was performed at T1 and T2, measuring nasal width, maxillary width, palatal height, maxillary arch perimeter, angulation of the upper first molar, and intermolar width. The mean palatal suture opening was 2.85 ± 0.62 mm (p < 0.0001). Nasal width increased 1.28 ± 0.64 mm and maxillary width 2.79 ± 1.48 mm (p < 0.0001). In contrast, palatal height was reduced 0.65 ± 0.64 mm (p < 0.0001). Regarding arch perimeter, the radicular perimeter increased 2.89 ± 1.80 mm, while the coronal perimeter increased 3.42 ± 2.09 mm (p < 0.0001). Molar angulation increased 5.62 ± 3.20° for the right molar and 4.74 ± 2.22° for the left molar (p < 0.0001). Intermolar width increased 5.21 ± 1.55 mm (p < 0.0001). Treatment with Hyrax produced a significant opening in the mean palatal suture. Also, a significant increase in nasal width, maxillary width, arch perimeter, molar angulation, and intermolar width, and a decrease in palatal height, were observed.

Orthodontic Localization of Impacted Canines: Review of the Cutting-edge Evidence in Diagnosis and Treatment Planning Based on 3D CBCT Images.

A thorough clinical and radiographical assessment of an impacted maxillary canine's location forms the basis for proper diagnosis and successful treatment outcomes. Implementing a correct biomechanical approach for directing force application primarily relies on its precise localization. Poor biomechanical planning can resorb the roots of adjacent teeth and result in poor periodontal outcomes of the canine that has been disimpacted. Furthermore, treatment success and time strongly rely on an accurate assessment of the severity of impaction, which depends on its 3D spatial location. The evolution of cone-beam computed tomography (CBCT) radiographs provides more detailed information regarding the location of the impacted canines. In addition, the literature has shown that CBCT imaging has enhanced the quality of diagnosis and treatment planning by obtaining a more precise localization of impacted canines. This review article highlights current evidence regarding comprehensive evaluation of three-dimensional orientations of impacted canines on CBCT images for precise diagnosis and treatment planning.

The role of post-dilatation in carotid MicroNet-covered stent implantation, evaluated using 3D cone-beam CT angiography.

This study aims to assess the role and safety of post-dilatation in protected carotid artery stenting (PCAS) using the new MicroNet-covered 2nd-generation stent assessed by cone beam CT scans. From March 2020 to March 2022, patients were enrolled in the study according to CT angiography results based on the following criteria: Evidence of 70% to 99% carotid stenosis in asymptomatic patients and 50% to 99% in symptomatic patients, per the NASCET index. Using a FilterWire EZ™ (Boston Scientific, Natick, MA, USA) embolic protection system (EPS), MicroNet-covered stent PCAS was performed by two interventional radiologists with at least 8 years of experience in endovascular intervention. Each patient underwent post-dilatation following stent placement. Finally, a third radiologist (not participating in the interventional procedures) evaluated the cone beam CT scans and calculated residual stenosis. Major and minor complications were recorded in the 30 days following the procedure. A total of 192 patients (121 male, mean age 73±10 years) were included in the study, and all patients received post-dilatation following stent implantation. Technical successes were achieved in all procedures. Adverse events noted in this study were limited to periprocedural transient ischemic attacks that occurred in three out of 192 patients (1.6%) and showed a swift complete recovery. The post-dilatation balloon diameters used in the study were: 5.0 mm (30.3%), 5.5 mm (39.3%) and 6 mm (30.3%). Optimized postdilatation resulted in a significant increase in the final luminal area. Similar improvements were observed in all subtypes of plaque. Post-dilatation in protected CAS is safe and induces a significant improvement in the cross-sectional area regardless of the stenotic plaque.

The preliminary in vitro study and application of deep learning algorithm in cone beam computed tomography image implant recognition

To properly repair and maintain implants, which are bone tissue implants that replace natural tooth roots, it is crucial to accurately identify their brand and specification. Deep learning has demonstrated outstanding capabilities in analysis, such as image identification and classification, by learning the inherent rules and degrees of representation of data models. The purpose of this study is to evaluate deep learning algorithms and their supporting application software for their ability to recognize and categorize three dimensional (3D) Cone Beam Computed Tomography (CBCT) images of dental implants. By using CBCT technology, the 3D imaging data of 27 implants of various sizes and brands were obtained. Following manual processing, the data were transformed into a data set that had 13,500 two-dimensional data. Nine deep learning algorithms including GoogleNet, InceptionResNetV2, InceptionV3, ResNet50, ResNet50V2, ResNet101, ResNet101V2, ResNet152 and ResNet152V2 were used to perform the data. Accuracy rates, confusion matrix, ROC curve, AUC, number of model parameters and training times were used to assess the efficacy of these algorithms. These 9 deep learning algorithms achieved training accuracy rates of 100%, 99.3%, 89.3%, 99.2%, 99.1%, 99.5%, 99.4%, 99.5%, 98.9%, test accuracy rates of 98.3%, 97.5%, 94.8%, 85.4%, 92.5%, 80.7%, 93.6%, 93.2%, 99.3%, area under the curve (AUC) values of 1.00, 1.00, 1.00, 1.00, 1.00, 1.00, 1.00, 1.00, 1.00. When used to identify implants, all nine algorithms perform satisfactorily, with ResNet152V2 achieving the highest test accuracy, classification accuracy, confusion matrix area under the curve, and receiver operating characteristic curve area under the curve area. The results showed that the ResNet152V2 has the best classification effect on identifying implants. The artificial intelligence identification system and application software based on this algorithm can efficiently and accurately identify the brands and specifications of 27 classified implants through processed 3D CBCT images in vitro, with high stability and low recognition cost.

Real Time 4D-Cone Beam CT via Single-Angle Projection with Dual Attention Mechanism

The hypothesis is that dual attention integrated Residual Network (DA-ResNet) together with a Principal Component Analysis (PCA) model accurately maps the measured on-treatment CBCT projections from different phases to each phase's 3D-CBCT real timely. Finally, it achieves real time 4D-CBCT. The DA-ResNet contains a CBAM (Convolutional Block Attention Module) and a SPA (Spatial Pyramid Structure). Hundreds of forward projections from one view of patient 4D-CT were simulated to train DA-ResNet. The extracted motion features were expressed as PCA coefficients. To test DA-ResNet performance, several single measured on-treatment projection is sent into it and the network output several groups of PCA coefficients real timely. Each group of PCA coefficient stands for the corresponding deformation field between the 0% phase and the predicted phase that the PCA label stands for. In labels such as Mean Absolute Error (MAE), R square, Normalized Cross Correlation (NCC), Structural Similarity Index Measure (SSIM) were used to evaluate DA-ResNet performance with other state-of-the-art networks such as CNN/Unet/ResNet. DA-ResNet outperforms other popular networks on all of the quantification labels, with MAE (14.41 ± 8.85), R square (0.95 ± 0.07) in PCA coefficient prediction, and NCC (0.9981 ± 0.0006), SSIM (0.98 ± 0.04) in image reconstruction. Compared with conventional ResNet, DA-ResNet reduced MAE by 79%. Meanwhile R square rises from 0.88 to 0.95, NCC rises from 0.996 to 0.998, SSIM rises from 0.94 to 0.98. DA-ResNet offers a solution for real time on-treatment 4D-CBCT image guidance by using single 2D on-line projections. It offers better motion prediction and image reconstruction accuracy compared with traditional deep learning networks (e.g., CNN/Unet/ResNet). The initial results are promising. The prospect of clinical application needs further clinical verification.

The Suitability of Trabecular Patterns in the Assessment of Dental Implant Osseointegration Process through 2D Digital and 3D CBCT Radiographs.

The research aims to determine the suitability of the trabecular pattern in the assessment of the dental implant osseointegration process through two-dimensional (2D) digital and three-dimensional (3D) cone-beam computed tomography (CBCT) radiographs. This is a correlation description that explains the relationship between variables. The population consisted of 24 data points on 3D CBCT and 2D digital radiographs from the procedure after dental implants were inserted into the tibia of a New Zealand white rabbit (Oryctolagus cuniculus) on days 3, 14, and 28. The radiograph was selected based on the region of interest (ROI), which covers the peri-implant area with a width of 1 mm and length following the height of the implant. The ROI was analyzed for trabecular thickness (Tb.Th), separation (Tb.Sp), number (Tb.N), and fractal dimension. The intraclass correlation coefficient (ICC) was used to statistically test the data to assess the consistency of intraobserver measurements and the r value (Pearson's correlation coefficient). This determines the correlation between trabecular patterns in both radiographic modalities and the Bland-Altman plot to observe the limits of acceptable discrepancies. The ICC test showed high intraobserver consistency in trabecular pattern measurements on 2D digital radiographs and 3D CBCT. The trabecular space pattern and number showed an r value of 0.88 with radiographic modalities of 0.72 mm and 0.018, respectively. Additionally, the trabecular thickness and fractal dimension had an insignificant correlation, with an r value of 0.22, and the mean of the 2D radiograph was lower than that of CBCT. The 2D radiograph and 3D CBCT showed correlations in the trabecular number and space results but had no correlation in the trabecular thickness and fractal dimension results. Based on intraclass correlation analysis, 3D CBCT appeared to be more reliable for measuring trabecular patterns (Tb.Th, Tb.Sp, Tb.N, and fractal dimension) than 2D radiograph.

Investigating the link between frontal sinus morphology and craniofacial characteristics with sex: A 3D CBCT study on the South Indian population.

Background: Measurement of craniofacial parameters plays an important role in sex determination in forensic science. The present study was done using cone beam computed tomography (CBCT) scans to evaluate the morphologic structure of the frontal sinuses and compare it with the width of nasal, cranial, maxillary and mandibular width which might help us in sex determination. Methods: A cross-sectional retrospective study was conducted using 142 full field of view (FOV) scans of patients archived from the department. The width of the nose, cranium, maxilla, and mandibular width was measured and compared with the frontal sinus between the two sexes. Results: A paired t-test was done to compare the linear measurements for both sexes' right and left frontal sinuses. The measurements were higher in males when compared to females. There was a statistically significant asymmetry (larger dimension on the left side) of the anterioposterior (p-value of 0.012) and superior-inferior dimensions in males (p-value of 0.135). Spearman's correlation showed that frontal sinus correlated with other craniofacial parameters like nasal, cranial, maxillary and mandibular width among both sexes. The frontal sinus, nasal, cranial, maxillary and mandibular widths were higher in males when compared to females (independent t-test). Discriminant function scores showed 66-68% accuracy to discriminate sex, using the anteroposterior dimension and mandibular width. Conclusions: The measurement of craniofacial parameters using CBCT can aid in determining the sex of unidentified and decomposed bodies.

Incidental finding of impacted supernumerary teeth in cone-beam computed tomography 3D

Objectives: To evaluate the value of cone-beam CT (CBCT) in the diagnosis and orientation of impacted supernumerary teeth in the dental arches.&#x0D; Case Report: A 50 year old man came to the Udayana University Hospital with the chief complaint of missing bilateral posterior teeth of the mandible and wanted to make denture. Before the treatment begin, a panoramic radiographic examination was performed. The panoramic image shows an impacted supernumerary teeth on the inferior from lower right premolar. Due to the inability to determine the precise position of those teeth within the mandible and the possible vital structures surrounding, a CBCT imaging was taken. Examination of the images from the CBCT shows an impacted supernumerary teeth in the area of teeth 44 and 46.&#x0D; Conclusion: The position of the supernumerary teeth is varied in the mandible, and often causes permanent dentition complications. In this case CBCT imaging two supernumerary teeth were found in the tooth area 44-45 and 45-46. apical of the two germ teeth appear to be fully formed. Supernumerary crowns between teeth 44-45 inclined buccally &amp; between teeth 45-46 lingually. CBCT is crucial for exact localization, for treatment planning, and for the surgical approach in cases of multiple supernumerary teeth.

4D-CT deformable image registration using unsupervised recursive cascaded full-resolution residual networks.

A novel recursive cascaded full-resolution residual network (RCFRR-Net) for abdominal four-dimensional computed tomography (4D-CT) image registration was proposed. The entire network was end-to-end and trained in the unsupervised approach, which meant that the deformation vector field, which presented the ground truth, was not needed during training. The network was designed by cascading three full-resolution residual subnetworks with different architectures. The training loss consisted of the image similarity loss and the deformation vector field regularization loss, which were calculated based on the final warped image and the fixed image, allowing all cascades to be trained jointly and perform the progressive registration cooperatively. Extensive network testing was conducted using diverse datasets, including an internal 4D-CT dataset, a public DIRLAB 4D-CT dataset, and a 4D cone-beam CT (4D-CBCT) dataset. Compared with the iteration-based demon method and two deep learning-based methods (VoxelMorph and recursive cascaded network), the RCFRR-Net achieved consistent and significant gains, which demonstrated that the proposed method had superior performance and generalization capability in medical image registration. The proposed RCFRR-Net was a promising tool for various clinical applications.

Comparative evaluation of mutagenic effects of two cone-beam computed tomography in oral mucosa cells.

This pilot study aimed to evaluate the mutagenic effects in cells of the oral mucosa after exposure to two different cone beam computed tomography (CBCT). Eighteen adults were submitted to the different CBCT (Carestream CS8100 3D and I-CAT). The cells were collected immediately before the CBCT exposure and 10 days later, when the material was placed on a slide and stained using the Feulgen/Fast Green technique. Microscopic analysis counted micronuclei and other nuclear alterations, which are indicative of cytotoxicity such as pyknosis, karyolysis, karyorrhexis, and binucletion. 2000 cells were analyzed. The statistical analysis was performed with the Wilcoxon Signed-Rank test to compare the frequency of cellular alterations, and the Mann-Whitney U test to compare different CBCTs, both with a significance level of 5%. There was no statistically significant difference in the micronucleated cell count before and after the exposition to the ionizing radiation from I-CAT (p = .298) and CS8100 3D (p = .203) A significate increase of pyknosis (p < .001), karyolysis (p < .001), karyorrhexis (p < .001), and binucletion (p < .001) were noted on I-CAT CBCT. There was no statistically significant difference in cellular alterations in CS8100 3D CBCT. Despite the increase in micronuclei after exposure, this study indicates that there is no evidence of genotoxicity. On the other hand, the I-CAT CBCT produced cytotoxic effects.

Investigating the link between frontal sinus morphology and craniofacial characteristics with sex: A 3D CBCT study on the South Indian population

Background: Measurement of craniofacial parameters plays an important role in sex determination in forensic science. The present study was done using cone beam computed tomography (CBCT) scans to evaluate the morphologic structure of the frontal sinuses and compare it with the width of nasal, cranial, maxillary and mandibular width which might help us in sex determination. Methods: A cross-sectional retrospective study was conducted using 142 full field of view (FOV) scans of patients archived from the department. The width of the nose, cranium, maxilla, and mandibular width was measured and compared with the frontal sinus between the two sexes. Results: A paired t-test was done to compare the linear measurements for both sexes' right and left frontal sinuses. The measurements were higher in males when compared to females. There was a statistically significant asymmetry (larger dimension on the left side) of the anterioposterior (p-value of 0.012) and superior-inferior dimensions in males (p-value of 0.135). Spearman's correlation showed that frontal sinus correlated with other craniofacial parameters like nasal, cranial, maxillary and mandibular width among both sexes. The frontal sinus, nasal, cranial, maxillary and mandibular widths were higher in males when compared to females (independent t-test). Discriminant function scores showed 66-68% accuracy to discriminate sex, using the anteroposterior dimension and mandibular width. Conclusions: The measurement of craniofacial parameters using CBCT can aid in determining the sex of unidentified and decomposed bodies.

Faster and lower dose imaging: evaluating adaptive, constant gantry velocity and angular separation in fast low-dose 4D cone beam CT imaging.

The adoption of four-dimensional cone beam computed tomography (4DCBCT) for image-guided lung cancer radiotherapy is increasing, especially for hypofractionated treatments. However, the drawbacks of 4DCBCT include long scan times (∼240s), inconsistent image quality, higher imaging dose than necessary, and streaking artifacts. With the emergence of linear accelerators that can acquire 4DCBCT scans in a short period of time (9.2s) there is a need to examine the impact that these very fast gantry rotations have on 4DCBCT image quality. This study investigates the impact of gantry velocity and angular separation between x-ray projections on image quality and its implication for fast low-dose 4DCBCT with emerging systems, such as the Varian Halcyon that provide fast gantry rotation and imaging. Large and uneven angular separation between x-ray projections is known to reduce 4DCBCT image quality through increased streaking artifacts. However, it is not known when angular separation starts degrading image quality. The study assesses the impact of constant and adaptive gantry velocity and determines the level when angular gaps impair image quality using state-of-the-art reconstruction methods. This study considers fast low-dose 4DCBCT acquisitions (60-80s, 200-projection scans). To assess the impact of adaptive gantry rotations, the angular position of x-ray projections from adaptive 4DCBCT acquisitions from a 30-patient clinical trial were analyzed (referred to as patient angular gaps). To assess the impact of angular gaps, variable and static angular gaps (20°, 30°, 40°) were introduced into evenly separated 200 projections (ideal angular separation). To simulate fast gantry rotations, which are on emerging linacs, constant gantry velocity acquisitions (9.2s, 60s, 120s, 240s) were simulated by sampling x-ray projections at constant intervals using the patient breathing traces from the ADAPT clinical trial (ACTRN12618001440213). The 4D Extended Cardiac-Torso (XCAT) digital phantom was used to simulate projections to remove patient-specific image quality variables. Image reconstruction was performed using Feldkamp-Davis-Kress (FDK), McKinnon-Bates (MKB), and Motion-Compensated-MKB (MCMKB) algorithms. Image quality was assessed using Structural Similarity-Index-Measure (SSIM), Contrast-to-Noise-Ratio (CNR), Signal-to-Noise-Ratio (SNR), Tissue-Interface-Width-Diaphragm (TIW-D), and Tissue-Interface-Width-Tumor (TIW-T). Patient angular gaps and variable angular gap reconstructions produced similar results to ideal angular separation reconstructions, while static angular gap reconstructions produced lower image quality metrics. For MCMKB-reconstructions, average patient angular gaps produced SSIM-0.98, CNR-13.6, SNR-34.8, TIW-D-1.5mm, and TIW-T-2.0mm, static angular gap 40° produced SSIM-0.92, CNR-6.8, SNR-6.7, TIW-D-5.7mm, and TIW-T-5.9mm and ideal produced SSIM-1.00, CNR-13.6, SNR-34.8, TIW-D-1.5mm, and TIW-T-2.0mm. All constant gantry velocity reconstructions produced lower image quality metrics than ideal angular separation reconstructions regardless of the acquisition time. Motion compensated reconstruction (MCMKB) produced the highest contrast images with low streaking artifacts. Very fast 4DCBCT scans can be acquired provided that the entire scan range is adaptively sampled, and motion-compensated reconstruction is performed. Importantly, the angular separation between x-ray projections within each individual respiratory bin had minimal effect on the image quality of fast low-dose 4DCBCT imaging. The results will assist the development of future 4DCBCT acquisition protocols that can now be achieved in very short time frames with emerging linear accelerators.

Comparison of infrazygomatic crest bone screw position using a postero-anterior cephalogram versus cone-beam computed tomography: a cross sectional study

Abstract Background The position of infrazygomatic crest bone screws is an important consideration in determining the success of orthodontic treatment. The aim of this study was to compare the position of infrazygomatic crest (IZC) bone screws in relation to skeletal and dental parameters using postero-anterior (PA) cephalograms and cone beam computed tomography (CBCT). Methods A CBCT scan and a PA cephalogram were taken of 19 patients (8 males; 11 females) after IZC bone screw placement. Each CBCT image was reconstructed and oriented using the CS 3D CBCT software (Carestream Dental LLC, Atlanta, USA) and was subsequently analysed. The landmarks were traced on the PA cephalogram. The angulation of the IZC bone screw was measured with respect to three skeletal and two dental landmarks and compared between the two imaging modalities. A paired t-test was applied to compare the means of different variables between the PA cephalogram and CBCT scan. Results The results showed no statistically significant difference between the two imaging modalities with respect to four landmarks, i.e., the inter-jugale plane, the mid sagittal plane, the zygomatic arch and the perpendicular long axis to the 1st molar but a small statistically significant difference was seen with respect to measurements from the facial surface of the 1st molar (P ≤ 0.05). Conclusion The angulation and position of an IZC bone screw are consistent between the two imaging modalities. A PA cephalogram may be used as a substitute for a CBCT scan to reduce the radiation exposure to patients.