Applications Of CBCT Research Articles

WE‐D‐BRB‐03: Current State of Volumetric Image Guidance for Proton Therapy

The goal of this session is to review the physics of proton therapy, treatment planning techniques, and the use of volumetric imaging in proton therapy. The course material covers the physics of proton interaction with matter and physical characteristics of clinical proton beams. It will provide information on proton delivery systems and beam delivery techniques for double scattering (DS), uniform scanning (US), and pencil beam scanning (PBS). The session covers the treatment planning strategies used in DS, US, and PBS for various anatomical sites, methods to address uncertainties in proton therapy and uncertainty mitigation to generate robust treatment plans. It introduces the audience to the current status of image guided proton therapy and clinical applications of CBCT for proton therapy. It outlines the importance of volumetric imaging in proton therapy. Learning Objectives: Gain knowledge in proton therapy physics, and treatment planning for proton therapy including intensity modulated proton therapy. The current state of volumetric image guidance equipment in proton therapy. Clinical applications of CBCT and its advantage over orthogonal imaging for proton therapy.B. Teo, B.K Teo had received travel funds from IBA in 2015.

WE‐D‐BRB‐02: Proton Treatment Planning and Beam Optimization

The goal of this session is to review the physics of proton therapy, treatment planning techniques, and the use of volumetric imaging in proton therapy. The course material covers the physics of proton interaction with matter and physical characteristics of clinical proton beams. It will provide information on proton delivery systems and beam delivery techniques for double scattering (DS), uniform scanning (US), and pencil beam scanning (PBS). The session covers the treatment planning strategies used in DS, US, and PBS for various anatomical sites, methods to address uncertainties in proton therapy and uncertainty mitigation to generate robust treatment plans. It introduces the audience to the current status of image guided proton therapy and clinical applications of CBCT for proton therapy. It outlines the importance of volumetric imaging in proton therapy. Learning Objectives: Gain knowledge in proton therapy physics, and treatment planning for proton therapy including intensity modulated proton therapy. The current state of volumetric image guidance equipment in proton therapy. Clinical applications of CBCT and its advantage over orthogonal imaging for proton therapy.B. Teo, B.K Teo had received travel funds from IBA in 2015.

WE‐D‐BRB‐04: Clinical Applications of CBCT for Proton Therapy

The goal of this session is to review the physics of proton therapy, treatment planning techniques, and the use of volumetric imaging in proton therapy. The course material covers the physics of proton interaction with matter and physical characteristics of clinical proton beams. It will provide information on proton delivery systems and beam delivery techniques for double scattering (DS), uniform scanning (US), and pencil beam scanning (PBS). The session covers the treatment planning strategies used in DS, US, and PBS for various anatomical sites, methods to address uncertainties in proton therapy and uncertainty mitigation to generate robust treatment plans. It introduces the audience to the current status of image guided proton therapy and clinical applications of CBCT for proton therapy. It outlines the importance of volumetric imaging in proton therapy. Learning Objectives: Gain knowledge in proton therapy physics, and treatment planning for proton therapy including intensity modulated proton therapy. The current state of volumetric image guidance equipment in proton therapy. Clinical applications of CBCT and its advantage over orthogonal imaging for proton therapy.B. Teo, B.K Teo had received travel funds from IBA in 2015.

WE‐D‐BRB‐00: Basics of Proton Therapy

The goal of this session is to review the physics of proton therapy, treatment planning techniques, and the use of volumetric imaging in proton therapy. The course material covers the physics of proton interaction with matter and physical characteristics of clinical proton beams. It will provide information on proton delivery systems and beam delivery techniques for double scattering (DS), uniform scanning (US), and pencil beam scanning (PBS). The session covers the treatment planning strategies used in DS, US, and PBS for various anatomical sites, methods to address uncertainties in proton therapy and uncertainty mitigation to generate robust treatment plans. It introduces the audience to the current status of image guided proton therapy and clinical applications of CBCT for proton therapy. It outlines the importance of volumetric imaging in proton therapy. Learning Objectives: Gain knowledge in proton therapy physics, and treatment planning for proton therapy including intensity modulated proton therapy. The current state of volumetric image guidance equipment in proton therapy. Clinical applications of CBCT and its advantage over orthogonal imaging for proton therapy.B. Teo, B.K Teo had received travel funds from IBA in 2015.

A Questionnaire Cross-Sectional Study on Application of CBCT in Dental Postgraduate Students.

SummaryBackgroundCBCT is a new emerging imaging technique which uses a cone-shaped radiation beam that is centered on a 2D detector. It is now routinely evaluated for oral and para-oral disorders. It has been widely accepted in practice in radiology in academic and hospital settings and included in the curricula of some countries. The present study aimed to evaluate the awareness of and knowledge on CBCT among postgraduates.Material/MethodsAfter obtaining permission and ethical clearance from concerned authorities, an anonymous survey on CBCT was conducted in a dental college by using a close-ended validated questionnaire to get to know the knowledge on CBCT among postgraduates in a dental college in India.ResultsA total of 100 volunteers participated but only 88 postgraduates responded to the questionnaire. Among the respondents, 54.5% were not using CBCT for diagnostic purposes at their work place. A total of 68.2% of respondents were partially aware of common terminologies used in CBCT. Most of the respondents were unsure about radiation exposure of CBCT when compared to other types of imaging. Almost nobody had any idea on relative importance of image characteristics. Only half of the respondents were willing to attend a hands-on course on CBCT interpretations versus pathology.ConclusionsIn the present study it was apparent that most of the respondents were lacking adequate knowledge on CBCT. Hence, there is an urgent need for more training programs on CBCT which would result in better diagnosis and treatment planning.

Cone-beam computed tomography usage: An alert to the field of dentistry.

Sir, Cone-beam computed tomography (CBCT) is a relatively novel technique for visualizing an individual tooth or dentition in relation to the surrounding skeletal tissues and for generating a three-dimensional image of the area to be studied.1,2 Since CBCT is extensively used in dental and maxillofacial imaging for the treatment planning of dental implants, endodontics, maxillofacial surgery, and orthodontics, it is imperative for operators and referring practitioners to comprehend the basic concepts of this imaging modality.3 Its widespread use and the fact that it involves greater radiation doses has given rise to numerous concerns regarding the rationalization and optimization of CBCT exposure, the training of CBCT operators, quality assurance for CBCT scanners, variations in image quality, differences in radiation doses in equipment made by different manufacturers, the inappropriate referral of patients for CBCT, and the need to safeguard staff from radiation exposure.4,5 Therefore, we absolutely agree with Jaju and Jaju's article6 entitled Cone-beam computed tomography: time to move from ALARA to ALADA, that is, moving from a paradigm of low as reasonably achievable to the goal of low as diagnostically acceptable. However, due to the absence of strict guidelines and the lack of experience regarding the role of CBCT in dentistry, CBCT has become an alternative to conventional radiography, including periapical, bitewing, and panoramic radiographs. The dosage delivered by CBCT results from several factors, such as the region of the jaw that is scanned, the exposure settings of the CBCT scanner, the size of the field of view (FOV), the exposure time (s), the tube current (mA), and the energy/potential (kV).7,8,9,10 Bearing in mind the greater radiation dose in comparison to conventional radiographs, it is essential that the potential benefits of CBCT outweigh the risks incurred through exposure to ionizing radiation.11 Dentists must respect their principal ethical obligation to protect patients, and therefore indications for CBCT should be justified appropriately and its usage for screening purposes alone should be strictly avoided. Essentially, CBCT should be considered as an adjunct to standard oral imaging modalities rather than as an alternative. Unfortunately, guidelines on the clinical usage of CBCT are frequently poorly presented. Prospectively, guideline development panels must aim to carry out and report their work using the AGREE II tool as a means of raising standards and avoiding bias.5 Guideline creators should be certain to bring together a multidisciplinary team of stakeholders to frame strategies. They should carry out systematic reviews and critically assess the evidence, characterize the limitations of the presented evidence, and clearly link their commendations to the evidence. Guidelines should be methodically reviewed prior to publication. Clear implementation approaches as well as tools for monitoring and clinical assessment should be presented. CBCT imaging should only be recommended by a clinician who has undergone appropriate training in CBCT radiology and exhibits an acceptable knowledge concerning the applications of CBCT, along with experience in the interpretation of CBCT images and an appreciation of the limitations of CBCT.12,13 It is imperative for dentists to know and communicate the doses and the associated risks of specific examinations to their patients and referring practitioners. The American Dental Association Council on Scientific Affairs Council has encouraged CBCT operators to contribute to continuing education courses in order to ensure that practitioners have a satisfactory understanding of radiation safety in the dental care setting.14 Although the danger from dentomaxillofacial imaging is not especially high for an individual, when multiplied by the enormous number of patients who are exposed to diagnostic imaging, the radiation hazard becomes a noteworthy public health issue. As imaging experts, we should educate our coworkers about the difference in risk between diagnostically acceptable and attractive pictures.6 Since CBCT is a fundamental tool in innovative advanced dentistry, we strongly feel it must be taught rigorously in the undergraduate dental curriculum. Such a step forward will enrich the knowledge of our young graduates, enabling them to correctly understand its implications and its appropriate usage.

Angulations of Anterior Teeth With Reference to the Alveolar Bone Measured by CBCT in a Chinese Population.

To analyze angulations of anterior teeth with reference to the alveolar bone. Cone-beam computed tomographic (CBCT) images of 105 participants were taken with the same machine (ProMax 3D Max CBCT), showing the intact anterior teeth. The angulations formed between the long axis of the anterior teeth and the alveolus were measured using cross-sectional images. The thicknesses of alveolar bone on different area of root surfaces were also measured. Maxillary anterior teeth were found to be close to the buccal alveolar surface in apical level with the angulations referred to alveolar bone in center incisor, lateral incisor, and canine were 17.65 ± 6.8, 18.79 ± 7.4, and 23.82 ± 6.96 degrees, respectively. Means of angulations of mandibular anterior teeth were less than 8 degree. The thicknesses of buccal bone at mid-root level in 77% to 90% maxillary anterior teeth were less than 1 mm. The determinations provided high intrarater/interrater reliability. The application of CBCT is reliable for a complete calculation of angulations and thicknesses in a Chinese Han population. As a result, adequate planning combined with image examination preoperatively would contribute to a favorable outcome.

WE‐G‐204‐04: Focal Spot Deblurring For High Resolution Amorphous Selenium (aSe) Complementary Metal Oxide Semiconductor (CMOS) X‐Ray Detector

Purpose:CMOS‐based aSe detectors compared to CsI‐TFT‐based flat panels have the advantages of higher spatial sampling due to smaller pixel size and decreased blurring characteristic of direct rather than indirect detection. For systems with such detectors, the limiting factor degrading image resolution then becomes the focal‐spot geometric unsharpness. This effect can seriously limit the use of such detectors in areas such as cone beam computed tomography, clinical fluoroscopy and angiography. In this work a technique to remove the effect of focal‐spot blur is presented for a simulated aSe detector.Method:To simulate images from an aSe detector affected with focal‐spot blur, first a set of high‐resolution images of a stent (FRED from Microvention, Inc.) were acquired using a 75µm pixel size Dexela‐Perkin‐Elmer detector and averaged to reduce quantum noise. Then the averaged image was blurred with a known Gaussian blur at two different magnifications to simulate an idealized focal spot. The blurred images were then deconvolved with a set of different Gaussian blurs to remove the effect of focal‐spot blurring using a threshold‐based, inverse‐filtering method.Results:The blur was removed by deconvolving the images using a set of Gaussian functions for both magnifications. Selecting the correct function resulted in an image close to the original; however, selection of too wide a function would cause severe artifacts.Conclusion:Experimentally, focal‐spot blur at different magnifications can be measured using a pin hole with a high resolution detector. This spread function can be used to deblur the input images that are acquired at corresponding magnifications to correct for the focal spot blur. For CBCT applications, the magnification of specific objects can be obtained using initial reconstructions then corrected for focal‐spot blurring to improve resolution. Similarly, if object magnification can be determined such correction may be applied in fluoroscopy and angiography.

CBCT in orthodontics: assessment of treatment outcomes and indications for its use

Since its introduction into dentistry in 1998, CBCT has become increasingly utilized for orthodontic diagnosis, treatment planning and research. The utilization of CBCT for these purposes has been facilitated by the relative advantages of three-dimensional (3D) over two-dimensional radiography. Despite many suggested indications of CBCT, scientific evidence that its utilization improves diagnosis and treatment plans or outcomes has only recently begun to emerge for some of these applications. This article provides a comprehensive and current review of key studies on the applications of CBCT in orthodontic therapy and for research to decipher treatment outcomes and 3D craniofacial anatomy. The current diagnostic and treatment planning indications for CBCT include impacted teeth, cleft lip and palate and skeletal discrepancies requiring surgical intervention. The use of CBCT in these and other situations such as root resorption, supernumerary teeth, temporomandibular joint (TMJ) pathology, asymmetries and alveolar boundary conditions should be justified on the basis of the merits relative to risks of imaging. CBCT has also been used to assess 3D craniofacial anatomy in health and disease and of treatment outcomes including that of root morphology and angulation; alveolar boundary conditions; maxillary transverse dimensions and maxillary expansion; airway morphology, vertical malocclusion and obstructive sleep apnoea; TMJ morphology and pathology contributing to malocclusion; and temporary anchorage devices. Finally, this article utilizes findings of these studies and current voids in knowledge to provide ideas for future research that could be beneficial for further optimizing the use of CBCT in research and the clinical practice of orthodontics.

Fundamentals of cone beam computed tomography for a prosthodontist.

Cone beam computed tomography (CBCT, also referred to as C-arm computed tomography [CT], cone beam volume CT, or flat panel CT) is a medical imaging technique of X-ray CT where the X-rays are divergent, forming a cone.[1] CBCT systems have been designed for imaging hard tissues of the maxillofacial region. CBCT is capable of providing sub-millimeter resolution in images of high diagnostic quality, with short scanning times (10–70 s) and radiation dosages reportedly up to 15–100 times lower than those of conventional CT scans. Increasing availability of this technology provides the dental clinician with an imaging modality capable of providing a three-dimensional representation of the maxillofacial skeleton with minimal distortion. The aim of this article is to sensitize the Prosthodontist to CBCT technology, provide an overview of currently available maxillofacial CBCT systems and review the specific application of various CBCT display modes to clinical Prosthodontic practice. A MEDLINE search for relevant articles in this specific area of interest was conducted. The selected articles were critically reviewed and the data acquired were systematically compiled.

Three-dimensional Imaging in Implant Assessment for the Prosthodontist: Utilization of the Cone Beam Computed Tomography

ABSTRACT Background The evolution of cone beam computed tomo- graphy three-dimensional (CBCT 3D) imaging has dramatically changed the potential for presurgical and pretreatment planning, such that outcomes are more predictable and complications more avoidable. Purpose The purpose of this article was to systematically review scientific and clinical literature pertaining to the uses and benefits of 3D imaging CBCT for diagnosis and treatment planning in Implantology including prosthodontics. Materials and methods Various databases, like PubMed, EBSCOhost and ScienceDirect, were searched from 1998 to 2010 to retrieve articles regarding the clinical applications of CBCT in dentistry. Cone beam computed tomography in dentistry was used as a key phrase to extract relevant articles in dentistry. A manual search for the references from the retrieved articles was also completed. The articles published only in English, randomized clinical trials, prospective and retrospective clinical studies, laboratory and computer-generated research were included. The search revealed 540 articles of which 447 were irrele- vant to the study and therefore excluded. Results Cone beam computed tomography has created an opportunity for clinicians to acquire the highest quality diagno- stic images with an absorbed dose that is comparable to other dental radiological examinations and less than a conventional CT. Therefore, if placement of an implant might approach a nerve, invade the sinus, or penetrate out of the confines of the jawbone, the patient should be offered a discussion of CBCT 3D imaging. In addition, CBCT 3D patients should be advised of the risks, benefits and alternatives to such treatment, based upon any additional data provided by the imaging. How to cite this article Rodrigues SJ, Mundathaje M, Raju M, Qureshi S. Three-dimensional Imaging in Implant Assessment for the Prosthodontist: Utilization of the Cone Beam Computed Tomography. Int J Prosthodont Restor Dent 2014;4(1):23-33.

Applications of Cone Beam Computed Tomography in Endodontics: A Review

Aim: This review aims to provide comprehensive information related to the principles of Cone beam computed tomography and its potential applications in the management of various endodontic conditions. Methodology: A thorough and extensive electronic literature search was conducted utilizing PubMed, for articles related to endodontic applications of CBCT published during the period between January 2005 and September 30, 2013. Search words such as ‘principles of CBCT’, ‘endodontic applications of CBCT’ were employed to obtain information. Only those articles dealing with the principles and various endodontic applications of CBCT are included in this review. Results: The search revealed 258 articles, 70 of which were found to be relevant to the scope of this review and were used in this review CBCT is a revolutionary and innovative procedure that has changed the paradigms in the management of various endodontic conditions. The information provided by this tool–three dimensional view of anatomic and pathologic structures, ability to provide details of root and canal anatomy, assessment of dento-alveolar trauma, assessment of root resorptions, etc. has contributed substantially to its extensive utilization in a short period of time. Clinical Significance: CBCT can be used in the management of a variety of conditions like dento-alveolar truma, root resorptions, early apical periodontitis, roots and canals with unusual anatomy, dental anomalies, etc. The effective dose of CBCT (focused field of view) varies from 5-38.3 μSv. The effective dose of intra-oral periapical radiographs and panoramic radiographs are E‚8.3 μSv and 9-26 μSv respectively. Thus CBCT has an effective dose in the similar range of magnitude as other dental radiographs, but, its three dimensional imaging capability and 100% sensitivity (1.0) and specificity (1.0) makes it an invaluable tool in the field of endodontics.

Cone-beam computed tomography in the management of dentigerous cyst of the jaws: A report of two cases

Cone-beam computed tomography (CBCT) is an emerging technology finding application in all branches of dentistry. The current series highlights the application of CBCT in the preoperative assessment of dentigerous cyst of the jaws.

MO-D-BRC-10: A Low Dose CBCT Stochastic Model and Applications

Purpose: Patient dose from daily CBCT positioning has been much concerned. Decreasing the dose, however, results in lower image quality because of the increased relative noise. In this study, we build a simple model for the stochastic, and apply the result to improving the image quality. Methods: Assume the photon fluence from the source is governed by truncated Gaussian. We derived the expression of CBCT numbers as summation of a noiseless part and a stochastic part. The standard deviation(SD) of the later term was derived. On the other hand, we measured the SDs of CBCT numbers in the water equivalent region of a CatPhan phantom scanned by our Varian OBI system with various mAs values. Fitting the SD in our expression by using the measured, we then applied it to simulating low dose CBCT patient images from the normal dose CBCT image, and to improving low dose image quality. Results: The SD from our model changes with mAs in a very similar way to those measured. This may indicate the usefulness of our model. The magnitude of the truncated Gaussian is thus the only parameter that needs to be fitted in our model by comparing the value of SD with that from measured at a certain mAs. Our model produced low dose CBCT images stochastically equivalent to those from real scans. This would be useful for the study of low dose CBCT of patient. Finally, the image quality of low dose CBCT is significantly improved by applying our model. Thus, patient dose would be decreased without loss of image quality. Conclusions: A stochastic model for low dose CBCT image is proposed. The model is used to simulate low patient dose CBCT image and to improve the image quality. It is possible to acquire equivalent CBCT with significantly lower patient dose.

Clinical Application of 3D Imaging for Assessment of Treatment Outcomes

This paper outlines the clinical application of CBCT for assessment of treatment outcomes, and discusses current work to superimpose digital dental models and 3D photographs. Superimposition of CBCTs on stable structures of reference now allow assessment of 3D dental, skeletal and soft tissue changes for both growing and non-growing patients. Additionally, we describe clinical findings from CBCT superimpositions in assessment of surgery and skeletal anchorage treatment.

Absorbed dose and dose rate using the Varian OBI 1.3 and 1.4 CBCT system

According to published data, the absorbed dose used for a CBCT image acquisition with Varian OBI v1.3 can be as high as 100 mGy. In 2008 Varian released a new OBI version (v1.4), which promised to reduce the imaging dose. In this study, absorbed doses used for CBCT image acquisitions with the default irradiation techniques of Varian OBI v1.3 and v1.4 are measured.TLDs are used to derive dose distributions at three planes inside an anthropomorphic phantom. In addition, point doses and dose profiles inside a ‘stack’ of three CTDI body phantoms are measured using a new solid state detector, the CT Dose Profiler. With the CT Dose Profiler, the individual pulses from the X‐ray tube are also studied. To verify the absorbed dose measured with the CT Dose Profiler, it is compared to TLD. The image quality is evaluated using a Catphan phantom.For OBI v1.3, doses measured in transverse planes of the Alderson phantom range between 64 mGy and 144 mGy. The average dose is around 100 mGy. For OBI v1.4, doses measured in transverse planes of the Alderson phantom range between 1 mGy and 51 mGy. Mean doses range between 3‐35 mGy depending on CBCT mode. CT Dose Profiler data agree with TLD measurements in a CTDI phantom within the uncertainty of the TLD measurements (estimated SD ±10%). Instantaneous dose rate at the periphery of the phantom can be higher than 20 mGy/s, which is 10 times the dose rate at the center. The spatial resolution in v1.4 is not as high as in v1.3.In conclusion, measurements show that the imaging doses for default modes in Varian OBI v1.4 CBCT system are significantly lower than in v1.3. The CT Dose Profiler is proven fast and accurate for CBCT applications.PACS number: 87.53.Bn

ABSORBED DOSE AND DOSE RATE USING THE VARIAN OBI 1.3 AND 1.4 CBCT SYSTEM

According to published data, the absorbed dose used for a CBCT image acquisition with Varian OBI v1.3 can be as high as 100 mGy. In 2008 Varian released a new OBI version (v1.4), which promised to reduce the imaging dose. In this study, absorbed doses used for CBCT image acquisitions with the default irradiation techniques of Varian OBI v1.3 and v1.4 are measured. TLDs are used to derive dose distributions at three planes inside an anthropomorphic phantom. In addition, point doses and dose profiles inside a 'stack' of three CTDI body phantoms are measured using a new solid state detector, the CT Dose Profiler. With the CT Dose Profiler, the individual pulses from the X-ray tube are also studied. To verify the absorbed dose measured with the CT Dose Profiler, it is compared to TLD. The image quality is evaluated using a Catphan phantom. For OBI v1.3, doses measured in transverse planes of the Alderson phantom range between 64 mGy and 144 mGy. The average dose is around 100 mGy. For OBI v1.4, doses measured in transverse planes of the Alderson phantom range between 1 mGy and 51 mGy. Mean doses range between 3-35 mGy depending on CBCT mode. CT Dose Profiler data agree with TLD measurements in a CTDI phantom within the uncertainty of the TLD measurements (estimated SD +/- 10%). Instantaneous dose rate at the periphery of the phantom can be higher than 20 mGy/s, which is 10 times the dose rate at the center. The spatial resolution in v1.4 is not as high as in v1.3. In conclusion, measurements show that the imaging doses for default modes in Varian OBI v1.4 CBCT system are significantly lower than in v1.3. The CT Dose Profiler is proven fast and accurate for CBCT applications.

TU‐A‐224C‐01: Daily Localization II: EPID, MVCBCT

The Mega‐Voltage Cone‐Beam CT (MVCBCT) system provides a 3D image of the patient anatomy in the actual treatment position that can be tightly aligned to the planning CT, allowing daily verification and correction of the patient position moments before the dose delivery. Integrated onto a linear accelerator, the system consists of a new a‐Si flat panel adapted for MV imaging and a workflow application allowing the automatic acquisition of projection images at low dose rate, CBCT image reconstruction, CT to CBCT image registration and couch position adjustment. Moreover, MVCBCT provides accurate electron density and allows studies of dosimetrical impact of setup error, anatomical changes or presence of implanted metallic objects.This lecture will provide an overview of the physics characteristics of MV and MV CBCT imaging, acceptance testing and commissioning, acquisition and reconstruction, image registration, alignment precision and quality assurance procedures. An overview of the clinical applications will be provided. Finally, current challenges and future developments will be addressed.Educational Objectives:1. Understand the basics concepts of MV Cone‐Beam CT imaging.2. Understand the workflow and issues related to clinical applications of MV CBCT, including acquisition, reconstruction, registration and patient alignment.3. Understand the possibilities of 3D Imaging for patient alignment.This work was supported by Siemens Oncology Care Systems.