Use Of Cone Beam Computed Tomography Research Articles

1:57 PM; Abstract No. 253 - The use of cone beam CT in percutaneous nephrolithotomy

1:57 PM; Abstract No. 253 - The use of cone beam CT in percutaneous nephrolithotomy

Three-dimensional imaging modalities in endodontics.

Recent research in endodontics has highlighted the need for three-dimensional imaging in the clinical arena as well as in research. Three-dimensional imaging using computed tomography (CT) has been used in endodontics over the past decade. Three types of CT scans have been studied in endodontics, namely cone-beam CT, spiral CT, and peripheral quantitative CT. Contemporary endodontics places an emphasis on the use of cone-beam CT for an accurate diagnosis of parameters that cannot be visualized on a two-dimensional image. This review discusses the role of CT in endodontics, pertaining to its importance in the diagnosis of root canal anatomy, detection of peri-radicular lesions, diagnosis of trauma and resorption, presurgical assessment, and evaluation of the treatment outcome.

Analysis of trabecular bone using site-specific fractal values calculated from cone beam CT images

Objective The purpose of the study was to explore the use of cone beam CT (CBCT) images to calculate fractal values of trabecular bone.

Use of cone beam CT in children and young people in three United Kingdom dental hospitals.

There is limited evidence about the use of cone-beam computed tomography (CBCT) in paediatric dentistry. Appropriate use of CBCT is particularly important because of greater radiation risks in this age group. To survey the use of CBCT in children and young people in three Dental Hospitals in the United Kingdom (UK), with special attention paid to aspects of justification and optimisation. Retrospective analysis of patient records over a 24-month period, looking at CBCT examinations performed on subjects under 18 years of age. Clinical indications, region of interest, scan field of view (FoV), incidental findings and exposure factors used were recorded. There were 294 CBCT examinations performed in this age group, representing 13.7% of all scanned patients. CBCT was used more frequently in the >13 year age group. The most common use was for localisation of unerupted teeth in the anterior maxilla and the detection of root resorption. Optimisation of X-ray exposures did not appear to be consistent. When planning a CBCT service for children and young people, a limited FoV machine would be the appropriate choice for the majority of clinical requirements. It would facilitate clinical evaluation of scans, would limit the number of incidental findings and contribute to optimisation of radiation doses.

An autopsy case of otogenic intracranial abscess and meningitis with Bezold’s abscess: Evaluation of inflammatory bone destruction by postmortem cone-beam CT

The deceased was an unidentified young male found unconscious on a walkway. On autopsy, outer and inner fistulae of the left temporal bone, subcutaneous abscess in the left side of the neck and head, and an intracranial abscess were noted. A portion of the left temporal bone was removed and scanned by cone-beam computed tomography (CT) (normally used for dentistry applications) to evaluate the lesion. The cone-beam CT image revealed roughening of the bone wall and hypolucency of the mastoid air cells, consistent with an inflammatory bone lesion. According to autopsy and imaging findings, the cause of death was diagnosed as intracranial abscess with Bezold's abscess secondary to left mastoiditis as a complication of otitis media. Although determining the histopathology of bone specimens is time-consuming and costly work, we believe that use of cone-beam CT for hard tissue specimens can be useful in forensic practice.

Dosimetry of CBCT: methods, doses and clinical consequences

The use of Cone beam CT (CBCT) systems for Image Guided Radiotherapy is rapidly expanding in the developed world. With its use comes concern for the increased risks of additional radiation exposure. Quantification of the imaging dose is necessary in order to report, optimise and justify CBCT exposures. This article reviews the current methods of dose measurement and calculation including dose measurements in cylindrical phantoms, use of point dosimeters in anthropomorphic phantoms, calculation of dose using mathematical phantoms and calculation of individualised patient dose using Monte Carlo and model based techniques. Typical doses from commercial systems are reported and the clinical consequences, both risks and benefits, of using CBCT based IGRT reviewed briefly.

Comparison of observer reliability of three-dimensional cephalometric landmark identification on subject images from Galileos and i-CAT cone beam CT

Recently, there has been increasing interest in the use of cone beam CT (CBCT) for three-dimensional cephalometric analysis and craniofacial reconstruction in orthodontic and orthognathic surgical treatment planning. However, there is a need to redefine the cephalometric landmarks in three dimensional cephalometric analysis and to demonstrate the reproducibility of landmark identification on the type of CBCT machine being used. CBCT images of 20 subjects aged 15-25 years were selected, ten each from Galileos(®) (Sirona Dental Systems Inc., Bensheim, Germany) and Next Generation i-CAT(®) (Imaging Sciences International, Hatfield, PA). 2 observers located 18 landmarks on each subject twice using Dolphin-3D v. 11 software (Dolphin Imaging and Management Systems, Chatsworth, CA). Inter- and intraobserver reliability was assessed using Euclidean distances and linear mixed models. Overall, the intra- and interobserver reliability was excellent for both machines. The landmarks Gonion, Nasion, Orbitale and Anterior Nasal Spine (ANS) showed the greatest median Euclidean distances for both intra- and interobserver measurements. There were significant observer effects in the unified models for Sella, Menton and all six dental landmarks. For Sella, the distances between the measures were significantly smaller (more closely spaced) on the i-CAT machine than on the Galileos in both intra- and interobserver measurements. The intra- and interobserver reliability was excellent for both machines. Some of the landmarks were not as reproducible as others. Which machine produced the highest reliability depended on the landmark considered.

Clinical implementation of kilovoltage cone beam CT for the verification of sequential and integrated photon boost treatments for breast cancer patients

The objective of this study was to formulate a practical method for the use of cone beam CT (CBCT) for the verification of sequential and integrated tumour bed boosts for early breast cancer patients. Partial arc scan geometries were assessed on a treatment unit. Imaging dose measurements on an Elekta Synergy CBCT system were made in a CT dose phantom for scan parameters 100 kV, 25 mA and 40 ms with an S20 collimator. The protocol was used to verify the setup of a cohort of 38 patients, all of whom had surgical clips inserted in the tumour bed. Setup errors with and without an extended no action level (eNAL) protocol were calculated. Arcs from 260° to 85° (left breast) and 185° to 15° (right breast) were found sufficient to image fiducial markers and anatomy whilst accounting for the physical limits of the equipment. A single treatment and imaging isocentre was found by applying simple constraints: isocentre <8 cm from midline and isocentre-couch distance <30 cm. Contralateral breast doses were ∼2 mGy per scan (right breast) and ∼12 mGy (left breast). Both mean population systematic error and mean population random error were 3 mm prior to correction. The systematic error reduced to 1.5 mm using an eNAL correction protocol, implying that a 5-mm setup margin could be achieved. An image-guided verification protocol using CBCT for breast cancer boost plans was implemented successfully. Setup errors were reduced with an acceptable imaging dose to the contralateral breast.

Cone beam computed tomography use in orthodontics

Cone beam computed tomography (CBCT) is widely used by orthodontists to obtain three-dimensional (3-D) images of their patients. This is of value as malocclusion results from discrepancies in three planes of space. This review tracks the use of CBCT in orthodontics, from its validation as an accurate and reliable tool, to its use in diagnosing and treatment planning, and in assessing treatment outcomes in orthodontics.

Cone beam CT sialography of Stafne bone cavity

Stafne bone cavity (SBC) was mostly described as a small oval radiolucency in the posterior mandibular region. To the best of our knowledge, the literature does not contain any report of the use of cone beam CT (CBCT) sialography for the diagnosis of this entity. The aim of this paper is to present a large, irregular and expanded atypical SBC, which made diagnosis difficult. A CBCT sialography was performed to get a definite diagnosis of this rare entity.

De la radiothérapie guidée par l’image à la radiothérapie guidée par la dose

Purpose In case of tumour displacement, image-guided radiotherapy (IGRT) based on the use of cone beam CT (tomographie conique) allows replacing the tumour under the accelerator by rigid registration. Anatomical deformations require however replanning, involving an estimation of the cumulative dose, session after session. This is the objective of this study. Patients and methods Two examples of arc-intensity modulated radiotherapy are presented: a case of prostate cancer (total dose = 80 Gy) with tomographie conique (daily prostate registration) and one head and neck cancer (70 Gy). For the head and neck cancer, the patient had a weekly scanner allowing a dose distribution calculation. The cumulative dose was calculated per voxel on the planning CT after deformation of the dose distribution (with trilinear interpolation) following the transformation given by a non-rigid registration step (Demons registration method) from: either the tomographie conique (prostate), or the weekly CT. The cumulative dose was eventually compared with the planned dose. Results In cases of prostate irradiation, the “cumulative” dose corresponded to the planned dose to the prostate. At the last week of irradiation, it was above the planned dose for the rectum and bladder. The volume of rectal wall receiving more than 50 Gy (V50) was 20% at the planning and 26% at the end of treatment, increasing the risk of rectal toxicity (NTCP) of 14%. For the bladder wall, V50 were 73% and 82%, respectively. In head and neck, the “cumulative” dose to the parotid exceeded the planned dose (mean dose increasing from 46 Gy to 54 Gy) from the 5th week of irradiation on, suggesting the need for replanning within the first 5 weeks of radiotherapy. Conclusion The deformable registration estimates the cumulative dose delivered in the different anatomical structures. Validation on digital and physical phantoms is however required before clinical evaluation.

High-grade primary leiomyosarcoma in the mandible: Diagnosis and treatment

Leiomyosarcoma is a malignant tumor that originates in smooth muscle cells and is rarely found in the oral cavity. We present a case of high-grade primary leiomyosarcoma in the mandible and discuss the diagnosis process. The patient was a 64-year-old white man who had a slight increase in volume in the left-side mandible with a radiolucent osteolytic image with the destruction of the mandibular cortex. Incisional biopsy and preoperative examination were performed, including cone beam CT and examination by immunohistochemistry that defined the histologic diagnosis of leiomyosarcoma. The patient underwent reconstruction with an osteocutaneous flap with microvascular anastomosis. Two years after the surgery, there was no sign of recurrence of the lesion. The use of cone beam CT to define the limits of the lesion and the immunohistochemical findings were essential to establish the treatment plan.

A comparison of 3D cone-beam Computed Tomography (CT) image reconstruction performance on homogeneous multi-core processor and on other processors

Computed Tomography (CT) has become an important noninvasive tool in diagnostic medicine. In fact, the use of cone-beam CT is growing in the clinical area due to its ability to provide 3D volumetric information. This study aims to parallelize an analytical 3D image reconstruction algorithm and then implement it on a commercial homogeneous multi-core processor. It is indicated from our results that the homogeneous multi-core processor actually achieved faster reconstruction than the heterogeneous processor-based or the FPGA-based implementation. Our results demonstrated that the shared cache mechanism associated with the homogeneous processor would represent a significant benefit to performing high-speed CT reconstruction or other High Performance Computing (HPC) applications. In addition, while the Graphic Processing Unit (GPU) is considered the most powerful processor nowadays, our experimental results further indicated that the joint use of the multi-core CPU and GPU could enhance the processing power as well as improve the computational efficiency.

SU‐E‐J‐182: Development of a Tomosynthesis Algorithm to Reduce Cone Beam Imaging Dose

Purpose: To develop a tomosynthesis cone beam reconstruction algorithm for LINAC cone beam CT with the goal to achieve a dose reduction better than 1/5 in current cone beam imaging protocols for patient positioning and portal beam verification while maintaining the required image quality for patient positioning and beam delivery verification. Methods: Tomosynthesis is the process of reconstructing tomographic images with fewer acquired projection images and additional synthetically generated projections to preserve image resolution and contrast. We developed a tomosynthesis cone beam reconstruction algorithm based on combining Feldkampˈ s cone beam reconstruction algorithm and an iterative maximum likelihood reconstruction algorithm. The Feldkamp method is used to reconstruct the first estimate of the tomographic data and the iterative maximum likelihood algorithm improves the resolution, contrast and considerably eliminates ghost images from the first estimate. Results: The algorithm tests show image reconstruction with the adequate image quality, contrast and resolution for patient positioning and beam delivery verification with a 1/8 dose delivered reduction using current cone beam imaging set‐up protocols. Imaging time is reduced with the same proportion allowing higher patient throughput. The algorithm has been tested using patient data for head and neck and brain treatment sites. On both treatment sites, portal beam and patient localization can be effectively performed within 3 mm accuracy using digitally reconstructed radiographs generated from the tomosynthesis reconstructed patient anatomical image. The reconstruction is executed on a desktop computer with 2GHz CPU and 4 Gb RAM in less than 5 minutes. Conclusions: We developed a tomosynthesis algorithm capable of reconstructing images with adequate resolution to perform beam delivery verification and patient positioning. This dose reduction will allow the daily use of cone beam CT in patients that require daily set‐up verification which currently is impractical because of dose and time constraints.

The use of cone beam CT for the removal of wisdom teeth changes the surgical approach compared with panoramic radiography: a pilot study

This prospective study evaluated the role of cone beam computed tomography (CBCT) in the treatment of patients with impacted mandibular third molars at increased risk of inferior alveolar nerve (IAN) injury. Subjects with an increased risk of IAN injury, as diagnosed on panoramic radiographs, were enrolled in this study and underwent additional CBCT imaging. Two oral maxillofacial surgeons independently planned the surgical technique and estimated the risk of IAN injury on panoramic radiographs and on CBCT images. A test of symmetry and the McNemar test were executed to calculate the differences between the two imaging modalities. The study sample comprised 40 patients (mean age 27.6 years) presenting 53 mandibular third molars. Risk assessment for IAN injury based on panoramic radiography compared with CBCT imaging differed significantly (P<0.005). After reviewing the CBCT images, significantly more subjects were reclassified to a lower risk for IAN injury compared with the panoramic radiograph assessments. This change in risk assessment also resulted in a significantly different surgical approach (P<0.03). The results of this study show that CBCT contributes to optimal risk assessment and, as a consequence, to more adequate surgical planning, compared with panoramic radiography.

The Use of Cone Beam CT for Treatment Verification in Prostate Radiotherapy

The Use of Cone Beam CT for Treatment Verification in Prostate Radiotherapy

Asymptomatic radiopaque lesions of the jaws: a radiographic study using cone-beam computed tomography

Panoramic radiography and cone-beam computed tomography (CT) were used to analyze asymptomatic radiopaque lesions in the jaw bones and determine the diagnostic relevance of the lesions based on their relationships to teeth and site of origin. One hundred radiopaque lesions detected between 1998 and 2002 were examined by both panoramic radiography and cone-beam CT. On the basis of panoramic radiographs, the region was classified as periapical, body, or edentulous, and the site was classified as molar or premolar. Follow-up data from medical records were available for only 36 of these cases. The study protocol for simultaneous use of cone-beam CT was approved by the ethics review board of our institution. A large majority of radiopaque lesions were observed in premolar and molar sites of the mandible; 60% of lesions were periapical, 24% were in the body, and 16% were in the edentulous region. An interesting type of radiopaque lesion, which we named a pearl shell structure (PSS), was observed on cone-beam CT in 34 of the 100 lesions. The PSS is a distinctive structure, and this finding on cone-beam CT likely represents the start of bone formation before bone sclerosis.

Percutaneous Radiofrequency Ablation of Osteoid Osteomas with Use of Real-Time Needle Guidance for Accurate Needle Placement: A Pilot Study

PurposeTo evaluate the accuracy and technical success of positioning a radiofrequency ablation (RFA) electrode in osteoid osteomas by use of a new real-time needle guidance technology combining cone-beam computed tomography (CT) and fluoroscopy.Materials and MethodsPercutaneous RFA of osteoid osteomas was performed in five patients (median age 18 years), under general anesthesia, with the use of cone-beam CT and fluoroscopic guidance for electrode positioning. The outcome parameters were technical success, meaning correct needle placement in the nidus; accuracy defined as the deviation (in mm) from the center of the nidus; and clinical outcome at follow-up.ResultsIn all five cases, positioning was possible within 3 mm of the determined target location (median nidus size 6.8 mm; range 5–10.2 mm). All procedures were technically successful. All patients were free of pain at clinical follow-up. No complications were observed.ConclusionReal-time fluoroscopy needle guidance based on cone-beam CT is a useful tool to accurately position radiofrequency needles for minimally invasive treatment of osteoid osteomas.

TU‐A‐204B‐02: On the Potential of CBCT for Range Verification in Proton Therapy

Purpose: We have investigated the potential use of cone beam CT (CBCT) for beam range verifications in proton therapy treatment, in addition to its primary role in geometric targeting. Specifically, we studied the intrinsic imaging variability of a CBCT and its effect on the water equivalent path length (WEPL) calculations, in the context of daily beam range verification/correction required for a recently proposed method of treating prostate using anterior fields. The current approach uses only lateral fields due to the lack of precise range control in patient. Materials and Methods: An anthropomorphic pelvic phantom was scanned using CBCT, in eight sessions on eight different days. In each session, the phantom was scanned twice, first at a standard position as determined by the room lasers, and then with a random shift of one centimeter in lateral directions. The Xio treatment planning system was used to perform the analysis. The average Hounsfield unit (HU) numbers for the water column in the rectal balloon was used to perform a linear calibration of the stopping power ratio, independently for each scan, as supported by the planning system. A number of WEPL values vertically from the anterior skin surface to the anterior surface of the water balloon were calculated on slices covering the region of the prostate, in relevance to a prostate treatment using an anterior field. Results: The HU number in the water column varied significantly even within the same CBCT. The average value also varied from day to day for up to 20 units. However, when these average values are used to calibrate the stopping power ratio, the variations in WEPL values along the anterior beam path are mostly within 2 mm. Conclusions: In‐room CBCT can be used in proton therapy to make online verification of protons range in patients with 2mm accuracy.

SU-GG-I-23: A Dosimetric Evaluation of Cone Beam CT Imaging in an Anthropomorphic Phantom

Purpose: There is a trend of increasing use of Cone Beam CT(CBCT) in radiation therapy as a method of tumor localization. Various papers have published methods for estimating this dose. However, this imagingdose is currently not accounted for in a patient's treatment, but will soon be able to be optimized within the treatment plan itself through modeling of the CBCT. Through verification of a CBCT model on an anthropomorphic phantom, this dose can begin to be accounted for clinically. Method and Materials:TLDs were placed at different locations and depths in an anthropomorphic phantom to map the dose delivered in a full CBCT scan as well as a half CBCT scan. Multiple readings were performed for each set up to confirm the repeatability of the TLD measurements. Analysis of these dose distributions were performed and compared to various reports of CBCTdose as well as directly compared with a Treatment Planning System model of CBCTDose.Results: The full CBCT scan TLD results show doses reaching a maximum of 5.92 +/− 0.21 cGy in soft tissue regions of a pelvis. Additionally, by reducing the scanning angle to half of the original scan, the highest doses were reduced by over 90% while providing adequate image information for the CBCT to localize the tumor volume. The results will be shown in comparison with the Treatment Planning Model of CBCTdose as well as compared with other published values. Conclusion: The TLD results show a need to better account for CBCTdose in a patient's treatment plan. Through further modeling of each CBCT parameter for each type of scan an accurate model can be put in place for each patient receiving radiation therapy. This will give the physicist and physician the ability to adjust treatment plans to account for imagingdose.