移動型術中コーンビームCTの顔面骨手術における使用経験

Mobile computed tomography (CT) with a cone-beam source is increasingly used in the clinical field. Mobile cone-beam CT (CBCT) has great merits; however, its clinical utility for brain imaging has been limited due to problems including scan time and image quality. The aim of this study was to develop a dedicated mobile volumetric CBCT for obtaining brain images, and to optimize the imaging protocol using a brain phantom. The mobile volumetric CBCT system was evaluated with regards to scan time and image quality, measured as signal-to-noise-ratio (SNR), contrast-to-noise-ratio (CNR), spatial resolution (10% MTF), and effective dose. Brain images were obtained using a CT phantom. The CT scan took 5.14 s at 360 projection views. SNR and CNR were 5.67 and 14.5 at 120 kV/10 mA. SNR and CNR values showed slight improvement as the x-ray voltage and current increased (p < 0.001). Effective dose and 10% MTF were 0.92 mSv and 360 μ m at 120 kV/10 mA. Various intracranial structures were clearly visible in the brain phantom images. Using this CBCT under optimal imaging acquisition conditions, it is possible to obtain human brain images with low radiation dose, reproducible image quality, and fast scan time.

Recent studies have demonstrated that shape-sensing robotic bronchoscopy with mobile cone-beam computed tomography (CBCT) guidance results in superb diagnostic outcomes for the diagnosis of peripheral lung lesions. Given the more favorable safety profile and the ability to also stage the mediastinum with endobronchial ultrasound when indicated, the combination of these technologies is likely to replace percutaneous computed tomography (CT)-guided biopsies of peripheral lung nodules in the years to come. Hands-on training in simulators, mannequins or cadaveric models is paramount before adopting this technique, but certain procedural and pre-procedural steps can only be practiced during true cases. Just like with any other new technology, there is an expected learning curve that physicians will go through before obtaining the desired procedural outcomes. Through the current manuscript we share some guidance based on years of research and clinical experience, which we hope will shorten the learning curve for newly adopters of these technologies. We have incorporated into our practice a systematic approach that maximizes the efficiency of patient positioning, integration of mobile CBCT and shape-sensing robotic bronchoscopy, as well as prevention of atelectasis and target motion. We believe this approach is key to maximizing efficiency and procedural outcomes, and we are honored to share it with the readers.

PurposePedicle screw fixation provides 3-column stabilization, multidimensional control, and a higher rate of interbody fusion. Although computed tomography (CT) is recommended for the postoperative assessment of pedicle screw fixation, its use is limited due to the radiation exposure dose. The purpose of this preliminary retrospective study was to assess the clinical usefulness of low-dose mobile cone-beam CT (CBCT) for the postoperative evaluation of pedicle screw fixation.MethodsThe author retrospectively reviewed postoperative mobile CBCT images of 15 patients who underwent posterior pedicle screw fixation for spinal disease from November 2019 to April 2020. Pedicle screw placement was assessed for breaches of the bony structures. The breaches were graded based on the Heary classification.ResultsThe patients included 11 men and four women, and their mean age was 66±12 years. Of the 122 pedicle screws, 34 (27.9%) were inserted in the thoracic segment (from T7 to T12), 82 (67.2%) in the lumbar segment (from L1 to L5), and six (4.9%) in the first sacral segment. Although there were metal-related artifacts, the image of the screw position (according to Heary classification) after surgery could be assessed using mobile CBCT at all levels (T7–S1).ConclusionsMobile CBCT was accurate in determining the location and integrity of the pedicle screw and identifying the surrounding bony structures. In the postoperative setting, mobile CBCT can be used as a primary modality for assessing the accuracy of pedicle screw fixation and detecting postoperative complications.

Soft-tissue complications after facial feminization bone surgery

Clinical indication for intraoperative 3D imaging during open reduction of fractures of the mandibular angle

SummaryComputed tomography (CT) is a widely utilised cross‐sectional imaging modality in the horse. However, most CT imaging of horses’ limbs has so far been restricted to applications under general anaesthesia. CT configurations that allow for imaging of the extremities in standing, sedated horses up to and including the carpus and tarsus have not yet been published. Here, a detailed description of the infrastructure and technical set‐up for CT examinations of horses’ limbs under standing sedation and using a mobile cone beam CT unit is provided.

Cleft lip and cleft palate are facial anomalies. One of the treatment for the patients is alveolar bone grafting. In Thailand, spiral CT scan has been extensively utilized in the diagnosis in order to examine the lesions on facial bone. However, spiral CT scans are expensive, relatively large and immobile. In this study, we evaluated the application of moveable CT scan. The important pre-operative information such as the shape of the alveolar cleft, the volume of the alveolar cleft, teeth, and tip of dental roots around alveolar cleft are required for treatment planning. Normally, plastic surgeons measured and evaluated these quantities in the operating room. Differently, the cleft lip and cleft palate patients underwent mobile CT for the pre-operative period. And with computer-aided design software, plastic surgeons worked collaboratively with engineers to process output and perform measurement pre-operatively. Our study shows that the pre-operative information from computer-aided design can increase understanding for alveolar cleft anatomy. The most important advantage of mobile CT and computer-aided design software is avoidance of dental root injury during alveolar bone graft operation.

The invention of flat-panel detectors led to a revolution in medical imaging. The major benefits of this technology are a higher image quality and dose reduction. Flat-panel detectors have proved to be superior to standard C-arms (= C-arm with radiograph source and image intensifier).Cone-beam computed tomography (cone-beam CT) is a 3D data set, which can be acquired with a flat-panel detector. The cone-shaped beam is used for 3D data generation. For cone-beam CT acquisition, the flat-panel detector rotates around the patient lying on the operating table. Intra-operative cone-beam CT can be a very helpful tool in orthopaedic surgery. Immediate control of fracture reduction and implant positioning in high image quality can reduce the need for secondary revision surgery due to implant malposition.In recent years there has been a revival of standard fan beam CT technology in operating rooms. Fixed and mobile systems are available. Fixed systems are typically placed on a sliding gantry. Different mobile intra-operative CT scanners were recently introduced. Due to their mobility, they are not bound to a specific operating room. The use of standard intra-operative CT scanners results in high 3D image quality but, in comparison with a cone-beam CT scanner, fluoroscopy is not possible.The introduction of flat-panel detectors has led to improvements in intra-operative image quality combined with dose reduction. The possibility of high-quality 3D imaging in combination with navigation can assure optimal implant placement. Due to immediate control of the osteosynthesis, revision surgery at a later time can be prevented.Cite this article: EFORT Open Rev 2018;3 DOI: 10.1302/2058-5241.3.170055

Real-time Intraoperative Computed Tomography Assessment of Quality of Permanent Interstitial Seed Implantation for Prostate Cancer

A system architecture has been developed for integration of intraoperative 3D imaging [viz., mobile C-arm cone-beam CT (CBCT)] with surgical navigation (e.g., trackers, endoscopy, and preoperative image and planning data). The goal of this paper is to describe the architecture and its handling of a broad variety of data sources in modular tool development for streamlined use of CBCT guidance in application-specific surgical scenarios. The architecture builds on two proven open-source software packages, namely the cisst package (Johns Hopkins University, Baltimore, MD) and 3D Slicer (Brigham and Women's Hospital, Boston, MA), and combines data sources common to image-guided procedures with intraoperative 3D imaging. Integration at the software component level is achieved through language bindings to a scripting language (Python) and an object-oriented approach to abstract and simplify the use of devices with varying characteristics. The platform aims to minimize offline data processing and to expose quantitative tools that analyze and communicate factors of geometric precision online. Modular tools are defined to accomplish specific surgical tasks, demonstrated in three clinical scenarios (temporal bone, skull base, and spine surgery) that involve a progressively increased level of complexity in toolset requirements. The resulting architecture (referred to as "TREK") hosts a collection of modules developed according to application-specific surgical tasks, emphasizing streamlined integration with intraoperative CBCT. These include multi-modality image display; 3D-3D rigid and deformable registration to bring preoperative image and planning data to the most up-to-date CBCT; 3D-2D registration of planning and image data to real-time fluoroscopy; infrared, electromagnetic, and video-based trackers used individually or in hybrid arrangements; augmented overlay of image and planning data in endoscopic or in-room video; and real-time "virtual fluoroscopy" computed from GPU-accelerated digitally reconstructed radiographs (DRRs). Application in three preclinical scenarios (temporal bone, skull base, and spine surgery) demonstrates the utility of the modular, task-specific approach in progressively complex tasks. The design and development of a system architecture for image-guided surgery has been reported, demonstrating enhanced utilization of intraoperative CBCT in surgical applications with vastly different requirements. The system integrates C-arm CBCT with a broad variety of data sources in a modular fashion that streamlines the interface to application-specific tools, accommodates distinct workflow scenarios, and accelerates testing and translation of novel toolsets to clinical use. The modular architecture was shown to adapt to and satisfy the requirements of distinct surgical scenarios from a common code-base, leveraging software components arising from over a decade of effort within the imaging and computer-assisted interventions community.

The aim of the present study was to explore the feasibility of ultrasonography (US) for clinical imaging of peri-implant tissues. Patients with ≥1 implant, a cone-beam computed tomography (CBCT) scan, an US scan, and clinical photographs taken during the surgery were included. The crestal bone thickness (CBT) and facial bone level (FBL) were measured on both US and CBCT modalities, and direct FBL measurements were also made on clinical images. US measurements were compared with CBCT and direct readings. A total of eight implants from four patients were included. For FBL measurements, US and direct (r2=0.95) as well as US and CBCT (r2=0.85) were highly correlated, whereas CBCT correlated satisfactorily with the direct reading (r2=0.75). In one implant without facial bone, CBCT was not able to measure CBT and FBL accurately. The estimated bias for CBT readings was 0.17±0.23mm (p=.10) between US and CBCT. US blood flow imaging was successfully recorded and showed a wide dynamic range among patients with different degrees of clinical inflammation. US is a feasible method to evaluate peri-implant facial crestal bone dimensions. Additional US features, for example, functional blood flow imaging, may be useful to estimate the extent and severity of inflammation.

Purpose – to analyze clinical cases of dacryocystitis after facial surgeries.. Material and methods Analysis of 6 clinical cases of complicated dacryocystitis was carried out based on our own experience of patient visits to the National Center of Ophthalmology named after Academician Zarifa Aliyeva in the period 2024-2025. The main complaints of all patients were watering eyes and purulent discharge. Patients associate the causes of the diseases with otolaryngological, dental surgeries, and facial injuries they underwent 1-2 years ago: 3 had rhinoplasty surgery, 1 had tooth implantation in the upper jaw, 1 had neoplasia of the nasal cavity and paranasal sinuses, and 1 had displaced fractures of the facial skeleton as a result of a car accident. It was possible to determine the level of obstruction of the damaged nasolacrimal ducts (NLD) based on computed tomography dacryocystography (CT-DCG). Conclusion In order to prevent complicated dacryocystitis, it is very important to pay attention to the protection of the tear ducts during surgeries on the face, and to be in close contact with ophthalmologists. In the postoperative period, timely detection and treatment of the inflammatory symptoms of NLD is one of the important points in the prevention of complicated dacryocystitis. It is advisable to perform a CT-DCG examination to determine the level of obstruction of the damaged NLD. Key words: dacryocystitis, lacrimal ducts, rhinoplasty, facial skeleton injuries, computed tomography dacryocystography

Cone beam computed tomography (CBCT) is widely used in many medical fields. However, conventional CBCT circular scans suffer from cone beam (CB) artifacts that limit the quality and reliability of the reconstructed images due to incomplete data. Saddle trajectories in theory might be able to improve the CBCT image quality by providing a larger region with complete data. Therefore, we investigated the feasibility and performance of saddle trajectory CBCT scans and compared them to circular trajectoryscans. We performed circular and saddle trajectory scans using a novel robotic CBCT scanner (Mobile ImagingRing (IRm); medPhoton, Salzburg, Austria). For the saddle trajectory, the gantry executed yaw motion up to using motorized wheels driving on the floor. An infrared (IR) tracking device with reflective markers was used for online geometric calibration correction (mainly floor unevenness). All images were reconstructed using penalized least-squares minimization with the conjugate gradient algorithm from RTK with voxel size. A disk phantom and an Alderson phantom were scanned to assess the image quality. Results were correlated with the local incompleteness value represented by , which was calculated at each voxel as a function of the source trajectory and the voxel's 3D coordinates. We assessed the magnitude of CB artifacts using the full width half maximum (FWHM) of each disk profile in the axial center of the reconstructed images. Spatial resolution was also quantified by the modulation transfer function at 10% (MTF10). When using the saddle trajectory, the region without CB artifacts was increased from 43 to 190mm in the SI direction compared to the circular trajectory. This region coincided with low values for . When was larger than 0.02, we found there was a linear relationship between the FWHM and . For the saddle, IR tracking allowed the increase of MTF10 from 0.37 to 0.98 lp/mm. We achieved saddle trajectory CBCT scans with a novel CBCT system combined with IR tracking. The results show that the saddle trajectory provides a larger region with reliable reconstruction compared to the circular trajectory. The proposed method can be used to evaluate other non-circulartrajectories.

Background: Several factors must be considered when selecting the appropriate field of view (FOV) and voxel size for good image quality on Cone Beam Computed-Tomography (CBCT). The purpose of this study is to determine the factors that must be considered in selecting the appropriate FOV and voxel size to achieve good image quality according to the purpose of the examination. Method: Articles in Q1 and Q2 journals published within the period from January 2016 to September 2021 were searched from Scopus and PubMed online using the keywords field of view/FOV in CBCT, voxel size in CBCT, and FOV and voxel size in CBCT. On the basis of the article selection criteria, 13 journals were included in the study. Also included in the study were several types of three-dimensional (3D) CBCT machines: Planmeca ProMax® 3D ProFaceTM, i-Cat Cone Beam 3D, Picasso Trio CBCT: Carestream unit® CS 9300 CBCT, and Accuitomo F17D 3D CBCT. Result: It is generally recommended that a 0.2 mm voxel size be used to detect periodontal disease, secondary caries, fractures, external resorption, and endodontic complications. Meanwhile, for root fractures with an intracanal metallic post and an anatomic isthmus in the root canal, a 0.1 mm voxel size is recommended to be used, and for evaluating the implant, 0.3 mm and 0.4 mm voxel sizes are recommended. Conclusion: It was found in the review that most of the selected studies recommended using the smallest FOV available in the CBCT unit to detect pathological conditions and important anatomical structures.

Histotripsy is a focal tumor therapy that utilizes focused ultrasound (US) to mechanically destroy tissue. To overcome visualization limitations of diagnostic US-guidance, C-arm cone beam CT (CBCT)-guided histotripsy is being developed, for which a mobile C-arm could increase accessibility. CBCT-guided histotripsy uses a phantom with a helical fiducial pattern to determine the CBCT-to-histotripsy robot coordinate transformation. This study presents an image-to-robot registration method requiring only one phantom CBCT, evaluated for accuracy and reproducibility using a mobile C-arm. The phantom is attached to a robotic arm (replacing the histotripsy transducer) and positioned at isocenter. A CBCT is acquired and image-to-robot registration performed by registering a digital model of the phantom to observed fiducials in CBCT coordinates. Registration was performed by one user (n=8/day, 2 days) and by 12 different users (n=4/day, 3 days) with fiducial registration errors (FREs) calculated. After each registration, the transducer was reattached to the robot and a treatment delivered in a multi-layered, agar-based phantom. Directional and target registration errors (TREs) were calculated as directional and Euclidean distances between planned and observed treatments. Directional error inter-day differences for the single-user experiment were evaluated for significance using 2-tailed unpaired Student t-tests. The effect of user variability on variability of FRE and directional error was evaluated for significance using 2-tailed F-tests. Registrations yielded FRE of 0.12±0.03mm and TRE of 1.51±0.83mm. Targeting error significantly increased along the transducer's short axis between days (0.88±0.60vs 1.43±0.18mm, p=0.025) for the single user, with a similar trend for the multi-user experiment (1.45±0.79, 2.70±0.19, and 2.83±0.40mm). User variability, and thus robot pose variability, did not significantly affect variability of FRE or directional error. Mobile C-arm CBCT-guided histotripsy showed high accuracy with minimal yet nonnegligible TREs, consistent within but not between days, demonstrating that errors can be measured and accounted for, ideally near treatment day to maximize accuracy.