Cone-beam Technology Research Articles

Quantitative assessment of the knee joint from weight bearing computed tomography

In recent years weight bearing computed tomography (WBCT) has been applied to the knee, delivering 3-D imaging in a physiologically loaded stance. Several quantitative approaches have been used to evaluate this data, with the greatest focus on joint space width (JSW) leading to 3-D JSW being potentially sensitive enough as a useful structural biomarker. Studies of JSW and lower limb alignment have been facilitated by novel technologies and have demonstrated significant differences between the non-weight bearing and weight bearing positions. Further work is needed to look at whole lower limb alignment that involves the interplay of all the joints of the lower limb. Steps are being taken to quantify bone parameters from cone beam technology, while there is an opportunity for contrast arthrography to evaluate articular cartilage and the meniscus in a weight bearing position. The concept of weight bearing imaging has also led to the evolution of different technology solutions, including different types of cone beam set up, upright and supine-loaded multidetector CT techniques. This latter approach has included kinematic CT with gating for acquisitions in different angles of flexion. WBCT has also been combined with MRI for finite element analysis of the meniscus. The increasingly varied applications of WBCT at the knee broadens its definition and hold potential for enhancing our understanding of factors in the onset and progression of osteoarthritis. However a consensus on standardized protocols will be required to facilitate these advances.

Significance of radiographic temporomandibular degenerative joint disease findings

The field of orthodontics has seen a recent increase in the number of patients over the age of 50 seeking treatment and also an increase in the use of cone beam technology. Similar to other joints in the body, the temporomandibular joint (TMJ) is associated with age-related degeneration. However, unlike other joints, degeneration of the TMJ is rarely symptomatic and when there is pain, it is usually self-limiting. In this article, we will review: (a) the incidence and prevalence of TMJ degenerative diseases, (b) similarities and differences of TMJ vs knee degenerative diseases, and (c) current treatment recommendations for TMJ degenerative diseases. In the vast majority of people, radiographic evidence of TMJ degeneration is an incidental finding. Future longitudinal research is needed to follow the natural course of TMJ degenerative patients.

A Review on Cone-Beam Computed Tomography and its Application in Dentistry.

Cone-beam computed tomography (CBCT), which has benefits over traditional radiography in this age of cutting-edge technology, has become increasingly popular in oral radiology. The utilization of CBCT is experiencing significant growth in several dental specialties, mainly for diagnostic purposes and treatment planning. Image acquisition and 3D imaging have helped the clinical use of cone-beam technology. The equipment has a user-friendly interface, minimum image distortion, and images compatible with many planning and simulation software applications. The present literature review aims to discuss CBCT and its various applications in dentistry.

3-D DISTRIBUTION OF BONE PARAMETERS ACROSS THE DISTAL FEMUR FROM WEIGHT BEARING CT FOLLOWS PATTERNS ACCORDING TO JOINT SPACE NARROWING PHENOTYPE: A MULTICENTER OSTEOARTHRITIS STUDY INVESTIGATION

Weight bearing CT (WBCT) technology has been increasingly used in imaging of knee osteoarthritis in recent years because of its ability to assess the weight bearing joint space. However, relatively little is known regarding the extent to which this cone beam technology can provide useful information on peri-articular bone beyond the subchondral regions. To explore relationships between WBCT-derived 3-D cortical bone thickness and trabecular bone attenuation at the distal femur with concurrent joint space narrowing phenotypes. WBCT imaging was obtained ancillary to the Multicenter Osteoarthritis Study at the 144-month visit. After semi-automatic segmentation, femoral cortical thickness (fCT) and trabecular attenuation (fTA) maps were created for each of 663 available distal femurs using cortical bone mapping. A template was registered to each individual distal femur and a 3-D statistical shape model created, followed by transfer of fCT and fTA distribution maps onto the template. A statistical parametric mapping (SPM) general linear model adjusted for age, sex, BMI, and the first 5 shape modes (controlling for effects of systematic misregistration) was used to test the dependence of fCT and fTA in turn on the experimental variables of concurrent radiographic medial and lateral OARSI joint space narrowing (JSN) grade. One knee from each participant was selected for inclusion, taking the side with worse compartmental baseline JSN grade or randomly if equal. 16 knees were excluded due to unachievable registration, with a final study set of a single knee from 386 individuals. 219 were female, mean ± SD age was 63.6 ± 9.6 yrs, mass 82.3 ± 17.7 kg, height 169 ± 9 cm, and BMI 28.5 ± 5.0 kg/m 2 . SPM significance ROIs according to baseline medial (left, figs 1 & 2) and lateral (right, figs 3 & 4) JSN phenotypes are shown for fCT (top row, figs 1 & 3) and fTA (bottom row, figs 2 & 4). SPM revealed significantly greater fCT by up to ∼0.1mm and fTA by up to ∼40 attenuation units (AU) for each increment in baseline JSN grade along the outer margin of the respective compartments (unmasked blue zones in each figure). Significantly greater fCT by up to ∼0.1mm for each increment in medial JSN grade also spread across the anterior aspect of the medial femoral condyle suggesting a wider regional relationship. 3-D distribution of fCT and fTA follow distinct patterns according to OARSI JSN phenotype, relating to recognised distributions of marginal osteophytosis and subchondral sclerosis. These results indicate that cone beam WBCT can quantify cardinal bony structural features of osteoarthritis and that their distribution is related to specific osteoarthritis OARSI JSN phenotypes. National Institutes of Health, University of Kansas (R01AR071648), University of Iowa. (U01AG18832), University of California-San Francisco (U01AG19069), Boston University (U01AG018820). NS is a consultant for Integra BioLife, Trice Medical and Pacira Biosciences. The authors would like to thank participants and staff of the MOST study. CORRESPONDENCE ADDRESS: tom@turmezei.com

Knowledge and Perception of Senior Dental Students Regarding Digital Dentistry and Its Use in Prosthodontics

Technology is becoming an ongoing expense as dentists across the globe expect Digital Radiology, Computer-Aided Design and computer-aided manufacturing (CAD/CAM), and 3D Cone Beam technology to be utilized in every practice in the future. To keep up with the rapidly increasing demand for digital technology in dentistry and meet new dental Accreditation Council (CODA) standards, dental education is making a solid transition to actively integrate technology into the curriculum. This is a cross-sec

Angular and linear measurements of adult flexible flatfoot via weight-bearing CT scans and 3D bone reconstruction tools

Acquired adult flatfoot is a frequent deformity which implies multiple, complex and combined 3D modifications of the foot skeletal structure. The difficult thorough evaluation of the degree of severity pre-op and the corresponding assessment post-op can now be overcome by cone-beam (CBCT) technology, which can provide access to the 3D skeletal structure in weight-bearing. This study aims to report flatfoot deformities originally in 3D and in weight-bearing, with measurements taken using two different bone segmentation techniques. 21 such patients, with indication for surgical corrections, underwent CBCT (Carestream, US) while standing on one leg. From these scans, 3D models of each bone of the foot were reconstructed by using two different state-of-the-art segmentation tools: a semi-automatic (Mimics Innovation Suite, Materialise, Belgium), and an automatic (Bonelogic Ortho Foot and Ankle, Disior, Finland). From both reconstructed models, Principal Component Analysis was used to define anatomical reference frames, and original foot and ankle angles and other parameters were calculated mostly based on the longitudinal axis of the bones, in anatomical plane projections and in 3D. Both bone model reconstructions revealed a considerable valgus of the calcareous, plantarflexion and internal rotation of the talus, and typical Meary’s angles in the lateral and transverse plane projections. The mean difference from these angles between semi-automatic and automatic segmentations was larger than 3.5 degrees for only 3 of the 32 measurements, and a large number of these differences were not statistically significant. CBCT and the present techniques for bone shape reconstruction finally provide a novel and valuable 3D assessment of complex foot deformities in weight-bearing, eliminating previous limitations associated to unloaded feet and bidimensional measures. Corresponding measurements on the bone models from the two segmentation tools compared well. Other more representative measurements can be defined in the future using CBCT and these techniques.

Cone Beam Technology

Cone Beam Technology

Techniques for 3D foot bone orientation angles in weight-bearing from cone-beam computed tomography

BackgroundFor the diagnosis and treatment of foot and ankle disorders, objective quantification of the absolute and relative orientation angles is necessary. The present work aims at assessing novel techniques for 3D measures of foot bone angles from current Cone-Beam technology. MethodsA normal foot was scanned via weight-bearing CT and 3D-model of each bone was obtained. Principal Component Analysis, landmark-based and mid-diaphyseal axes were exploited to obtain bone anatomical references. Absolute and relative angles between calcaneus and first metatarsal bone were calculated both in 3D and in a simulated sagittal projections. The effects of malpositioning were also investigated via rotations of the entire foot model. ResultsLarge angle variations were found between the different definitions. For the 3D relative orientation, variations larger than 10 degrees were found. Foot malposition in axial rotation or in varus/valgus can result in errors larger than 5 and 3 degrees, respectively. ConclusionsNew measures of foot bone orientation are possible in 3D and in weight-bearing, removing operator variability and the effects of foot positioning.

Practical radiation dosimetry across a variety of CBCT devices in Radiology

Cone beam technology is becoming more prominent in Radiology. In our hospital we have an extremity CT, an O-arm and a number of C-arms offering 3D capabilities. Each of these modalities use cone beam CT (CBCT) technology to image the area of interest in one single rotation. Traditional CTDI metrics for radiation dosimetry in CT depend on narrow beam geometry. The relevance of the CTDI as a dose indicator for cone beam scanning is contentious due to underestimation of dose lying outside the standard 100 mm chamber length and CTDI phantoms being of insufficient length.In an attempt to better quantify dose from cone beam scanning, alternative methodologies have been developed which attempt to counter the limitations of CTDI methodologies. In this comparison study we utilised the CBCT methodologies outlined in (i) IAEA Report 5, (ii) EFOMP’s protocol on QC in CBCT and (iii) conventional CTDI measurement and tested them on various CBCT systems used in Radiology. These methods were chosen as they use equipment that is typically available to a diagnostic imaging physicist.We determine that the EFOMP protocol and the conventional CTDI method produce the best estimate of the radiation output for quality control purposes. Our conclusion is that the EFOMP protocol is the fastest and easiest method to measure a CBCT metric but it is not always accessible. For the systems in our hospital we will adopt the EFOMP protocol for open systems (C-arms) and perform CTDIVol measurements using conventional techniques on enclosed systems (O-arm and extremity CT).

Weight-bearing CT Technology in Musculoskeletal Pathologies of the Lower Limbs: Techniques, Initial Applications, and Preliminary Combinations with Gait-Analysis Measurements at the Istituto Ortopedico Rizzoli.

Musculoskeletal radiology has been mostly limited by the option between imaging under load but in two dimensions (i.e., radiographs) and three-dimensional (3D) scans but in unloaded conditions (i.e., computed tomography [CT] and magnetic resonance imaging in a supine position). Cone-beam technology is now also a way to image the extremities with 3D and weight-bearing CT. This article discusses the initial experience over a few studies in progress at an orthopaedic center. The custom design of total ankle replacements, the patellofemoral alignment after medial ligament reconstruction, the overall architecture of the foot bones in the diabetic foot, and the radiographic assessment of the rearfoot after subtalar fusion for correction of severe flat foot have all taken advantage of the 3D and weight-bearing feature of relevant CT scans. To further support these novel assessments, techniques have been developed to obtain 3D models of the bones from the scans and to merge these with state-of-the-art gait analyses.

P1.17-29 8-year Experience of Navigational Bronchoscopy for Preoperative Localization of Subcentimeter Lung Nodules in a Small Community Hospital

With the advent of lung cancer screening, CT imaging has led to the identification of sub-centimeter nodules that are challenging to localize for both diagnosis and resection. The traditional approaches are problematic because biopsies often have poor diagnostic yield, resulting in repeat attempts at tissue collection, delay in time to treatment, and increased cost. Electromagnetic navigation bronchoscopy (ENB) is a newer technology that allows greater precision in preoperative localization of nodules to obtain tissue for diagnosis and fiducial marker placement. Our institution has adopted a practice that combines simultaneous ENB for nodule localization and video-assisted thoracoscopic surgery (VATS) for resection with single anesthetic administration and operating room team. We aimed to evaluate changes in time to treatment, time to surgery, and length of stay. Retrospective review of all patients who underwent nodule localization and VATS or robotic-assisted VATS (RATS) between (May 2011- March 2019). ENB localization was performed with transbronchial injection of ICG and/or placement of gold fiducial markers. A total of 72 patients underwent VATS or RATS. During the first two years of the study period, ENB was performed with portable C-arm fluoroscopic guidance with diagnostic yield of 48%. Surgery was performed on average 29.7 days (4-190 days) after ENB (3 patients had non-diagnostic bronchoscopy and were followed with serial CT scans that resulted in >100 days until surgery). In August 2017 utilization of Cone Beam CT scan began during ENB, which resulted in reduction in time to surgery to average of 20.1 days (1-39 days). After persistent low diagnostic yield with bronchoscopy and demand for expedient diagnosis, in February 2018, ENB and surgical resection were performed simultaneously with single anesthetic administration and OR team. Furthermore, in December 2018 utilization of daVinci Xi robot began for RATS with ICG injection during ENB for intraoperative localization of nodules. The hospital length of stay (LOS) and time to treatment (from the initial identification of a lung nodule to surgery) for Super D bronchoscopy group (SDB) (n=36) is 5.7/63.8 days, SDB-with cone beam technology (n=8) is 4.5/62.8 days, respectively. Transition to simultaneous resection (n=28) resulted in 100% diagnostic yield, further decrease of both hospital LOS and time to treatment, to 3.6 days and 43.7 days, respectively. Our data demonstrates that intraoperative ENB lung lesion localization with simultaneous VATS/RATS resection results in decreased hospital length of stay, reduced time to treatment, and 100% diagnostic yield. Both metrics significantly impact patient satisfaction and healthcare costs.

Importance of cone-beam computed tomography in dentistry: An update

In this era of advanced technology, cone-beam computed tomography (CBCT) has gained popularity in the field of oral radiology due to its advantages over conventional radiography. The use of CBCT is profoundly increasing for diagnosis and treatment planning in different specialties of dentistry. The incorporation of cone-beam technology into clinical practice is taking place because of the progress in image acquisition and three-dimensional (3D) imaging. The equipment design is easier to use, image distortion is minimal, and the images are compatible with other planning and simulation software. The 3D imaging has made the complex craniofacial structures more accessible for examination. Early and accurate diagnosis of deep-seated lesions is possible. CBCT provides a high-spatial resolution of bone and teeth which allows accurate understanding of the relationship of the adjacent structures. CBCT has helped in detecting a variety of cysts, tumors, infections, developmental anomalies, and traumatic injuries involving the maxillofacial structures. It has been used extensively for evaluating dental and osseous disease in the jaws. This paper reviews current advances in CBCT and their uses in dentistry.

Endodontic applications of cone beam computed tomography: case series and literature review

Cone beam computed tomography (CBCT) is a relatively new method that produces three-dimensional (3D) information of the maxillofacial skeleton, including the teeth and their surrounding tissue, with a lower effective radiation dose than traditional CT scans. Specific endodontic applications for CBCT are being identified as the use of this technology becomes more common. CBCT has great potential to become a valuable tool for diagnosing and managing endodontic problems, as well as for assessing root fractures, apical periodontitis, resorptions, perforations, root canal anatomy and the nature of the alveolar bone topography around teeth. This article aims to review cone beam technology and its advantages over CT scans and conventional radiography, to illustrate current and future clinical applications in endodontic practice, and to highlight areas of further research of CBCT in endodontics. Specific case examples illustrate how treatment planning has changed with the images obtained with CBCT technology compared with only periapical radiography.

Residents' journal review

Residents' journal review

Pediatric Interventional Radiology and Dose-Reduction Techniques

The pediatric interventional radiology community has worked diligently in recent years through education and the use of technology to incorporate numerous dose-reduction strategies. This article seeks to describe different strategies where we can significantly lower the dose to the pediatric patient undergoing a diagnostic or therapeutic image-guided procedure and, subsequently, lower the dose several fold to the staff and ourselves in the process. These strategies start with patient selection, dose awareness and monitoring, shielding, fluoroscopic techniques, and collimation. Advanced features such as cone-beam technology, dose-reduction image processing algorithms, overlay road mapping, and volumetric cross-sectional hybrid imaging are also discussed.

Atlas rotation and mandibular deviation by Cone Beam CT

Cervical vertebrae and mandible are functionally related and some evidences suggest a strong correlation between their relative position and orientation (Huggare et al., 1996; Nisayif et al., 2005). In this study TC Dental Scan with cone beam technology was used to study the relationship between atlas and mandibular rotation in 205 patients. Using a digitalized images analyser, we calculated the axial rotation of atlas and mandible, measuring the angle with respect to the frontal plane. We found that 80.98% of patients presented the axial rotation of the mandible in the same direction of atlas rotation compared with 19.02% of patients that presented opposite directions. Among the consistent group, 71.08% of patients had a left rotation compared with 28.92% that had a right rotation. Moreover, considering the absolute values of the rotation, we observed that the atlas had a more marked rotation with respect to the mandible and that the values of left rotations were higher with respect to the value recorded for right rotations both for the mandible and atlas measurements. This study represents a starting point to better characterize the relationship between atlas and mandible; further studies are necessary to better understand the importance of this data from a functional and clinical point of view.

The management of palatally displaced maxillary canines: Considerations and challenges

This article opens with a recognition that ectopic maxillary canines may lead to frank impactions requiring a coordinated and multidisciplinary approach to their surgical/orthodontic management and the potential benefit of managing canine ectopia, particularly palatally displaced canines, more conservatively in their pre-eruptive ectopic positions in an effort to avoid impaction. The prevalence of palatally displaced canines (PDC) in various populations and corroborating as well as competing or conflicting opinions of etiology are briefly reviewed. Some of the traditional as well as relatively newer strategies and associated investigations of managing pre-eruptive palatally displaced maxillary canines are discussed, and the imaging techniques utilized to identify and locate ectopic maxillary canines are also discussed. Early detection of ectopic canines must include at the very least panoramic and/or periapical radiographs as part of any mixed dentition orthodontic examination and assessment. The sometimes unpredictable continued path of the ectopic maxillary canine poses clinical and ethical issues to the clinician when developing treatment strategies as part of any overall orthodontic treatment plan for young patients presenting with maxillary canine ectopia. The need for more thoughtful and carefully designed randomized clinical trials with a greater emphasis on subject sample scrutiny is strongly recommended to add much needed clarity to the clinical management of ectopic maxillary canines.

Measurements of the dose delivered during CT exams using AAPM Task Group Report No. 111

The computed tomography dose index (CTDI) measured with a 10 cm long pencil ionization chamber placed in a 14 cm long PMMA phantom is typically used to evaluate the doses delivered during CT procedure. For the new generation of CT scanners, the efficiency of this methodology is low because it excludes the contribution of radiation scattered beyond the 100 mm range of integration along z. The AAPM TG111 Report proposes a new measurement modality using a small volume ionization chamber positioned in a phantom long enough to establish dose equilibrium at the location of the chamber. In this work, the AAPM report was implemented. The minimum scanning length needed to obtain cumulative dose equilibrium was evaluated. The equilibrium dose was determined and compared to CTDI values informed by the CT scanner, and the dose values were confirmed with TLD measurements. The difference between doses measured with TLD and with the ionization chamber (IC) was below 1% and the repeatability of the measurements' setup was 0.4%. The measurements showed that the scanning lengths needed to reach the cumulated dose equilibrium were 450 mm and 380 mm for the central and peripheral axes, respectively, which justifies the phantom length. For the studied clinical protocols, the doses measured were about 30% higher than those informed by the CT scanner. For the new generation of CT systems with wider longitudinal detector size or cone‐beam technology, the current CTDI measurements may no longer be adequate, and the informed CTDI tends to undervalue the dose delivered. It is therefore important to evaluate CT radiation doses following the AAPM TG111 methodology.PACS number: 87.57.qp, 87.53.Bn

Real-Time Imaging with the O-Arm for Skull Base Applications: A Cadaveric Feasibility Study

Introduction Although intraoperative imaging/navigation has established its critical role in neurosurgery, its role in cranial base surgery is currently limited. Due to issues such as poor bony resolution and accuracy, surgeons have to rely on anatomic landmarks that can be distorted by pathology when drilling out critical structures. Though originally developed for spinal application, we hypothesized that the O-Arm could address the above issues for use in cranial base procedures. Methods A cadaveric study was performed in which heads underwent a preprocedure scan via the O-Arm, a fluoroscopic device capable of providing three-dimensional images through the use of cone-beam technology. Preprocedure scans were taken and then registered to a Stealth S7 machine (Medtronic, Inc., Minneapolis, MN, USA). Key cranial base landmarks were identified on these scans and then subsequently identified under direct visualization after (1) endoscopic endonasal dissection and (2) a middle fossa approach. We then quantified the difference in distance between the preplanned and identified structure during surgery. This difference was considered the error. Results For anterior cranial fossa structures, the mean error was 0.25 mm (anterior septum), 0.27 mm (left septum), and 0.32 mm (right septum). For middle fossa structures, the errors were: 0.11 mm (foramen spinosum), 0.44 mm (foramen rotundum), and 0.21 mm (foramen ovale). Conclusion Based on this preliminary cadaveric study, we feel the O-Arm can provide the necessary imaging resolution at the skull base to be employed for intraoperative navigation during cranial base approaches (open and endoscopic). This study warrants further investigation into its clinical use in patients undergoing similar surgical procedures.

Characterization of RDX-Based Thermosetting Plastic-Bonded Explosive by Cone-Beam Microfocus Computed Tomography

In this study microfocus computed tomography (μCT), a nondestructive technique, was used for 3D characterization of cyclotrimethylenetrinitramine (RDX)-based thermosetting plastic-bonded explosives. Quantitative information on RDX crystals including the packing status of the crystal and binder system, as well as the inner structure characteristics of partially solidified and fully solidified samples, was obtained using cone-beam μCT technology. The CT images show that the CT value of RDX crystal grains was obviously higher than that of crystal powder/binder. The results also show that after vacuum casting and thermosetting, the RDX grains were dispersed evenly and there were no air pores or cracks observed in the sample. Small pores exist inside the RDX grains with a porosity of less than 0.3%. The analysis results indicate high quality of the explosive part after employing thermosetting molding. The binder system and RDX crystals were integrated sufficiently, yet the grain packing was not maximum. The estimated average density and maximal difference in density of the sample were both in accordance with the testing results by Archimedes’ method and it was proven that complete curing may enhance the overall density and density uniformity of the product.