Article

Applications of CBCT in OMS: An Overview of Published Indications, and Clinical Usage in US Academic Centers and OMS Practices

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Abstract

Purpose The American Association of Oral and Maxillofacial Surgeons appointed a task force to study the indications, safety, and clinical practice patterns of cone-beam computed tomography (CBCT) in oral and maxillofacial surgery (OMS). The charge was to review the published applications of CBCT in OMS, identify the current position of academic thought leaders in the field, and research the adoption and usage of the technology at the clinical practitioner level. Materials and Methods This study reviewed the CBCT world literature and summarized published indications for the modality. A nationwide survey of academic thought leaders and practicing oral and maxillofacial surgeons was compiled to determine how the modality is currently being used and adopted by institutions and practices. Results This report summarizes published applications of CBCT that have been vetted by the academic and practicing OMS community to define current indications. The parameters of patient safety, radiation exposure, accreditation, and legal issues are reviewed. An overview of third-party adoption of CBCT is presented. Conclusion CBCT is displacing 2-dimensional imaging in the published literature, academia, and private practice. Best practices support reading the entire scan volume with a written report defining results, patient exposure, and field of view. Issues of patient safety, ALARA (“as low as reasonably achievable”), accreditation, and the legal and regulatory environment are reviewed. Third-party patterns for reimbursements vary widely and seem to lack consistency. There is much confusion within the provider community about indications, authorizations, and payment policies. The current medical and dental indications for CBCT in the clinical practice of OMS are reviewed and an industry guideline is proposed. These guidelines offer a clear way of differentiating consensus medical indications and common dental uses for clinicians. This matrix should bring a predictable logic to third-party authorizations, billing, and predictable payments for this emerging technology in OMS.

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... In a study conducted by Carter et al. on CBCT indications of oral surgeons, it was reported that jaw-facial pathologies and dental implants (95%), evaluation of supernumerary teeth (91.9%) and sinus lifting planning (81.4%) were among the most common indications. 21 Some studies have shown that dental surgeons use CBCT most frequently during the implant planning stage. 15 In another study evaluating the attitudes of orthodontists towards CBCT, it was reported that this method was used for the detection of impacted teeth (80.9%) and for evaluation of oral and craniofacial anomalies such as cleft lip and palate (57.4%). ...
... The Internet was also considered another resource for updating information. 21 In another study among endodontists, scientific meetings and congresses organized by associations and universities were reported to help promote further education. The Internet was also considered as another resource used by endodontists to update their knowledge. ...
... The Internet was also considered as another resource used by endodontists to update their knowledge. 21 In this study, it was reported that pedodontists in Turkey most commonly gained information on CBCT from universities as well as through the Internet and private courses. ...
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Amaç: Konik Işınlı Bilgisayarlı Tomografi (KIBT) gibi konvansiyonel görüntüleme yöntemlerine göre daha fazla radyasyon dozu gerektiren yöntemlerin çocuklarda kullanımı ve endikasyonları hala tartışmalıdır. Bu makalede, Türk pedodontistleri arasında KIBT kullanım sıklığı, endikasyonlarını değerlendirmek ve eğitim ihtiyacının anlaşılması amaçlanmıştır. Materyal ve Metod: Elektronik ortamdan 210 pedodontiste sosyodemografik özellikleri ve KIBT kullanımını değerlendiren, iki kısımdan oluşan anket uygulandı. Anketin bir bölümünde pedodontistlerin cinsiyet ve yaş gibi demografik özellikleri ile ilgili sorular vardı. Diğer bölümde, KIBT kullanımı ile ilgili sorular vardı. Tamamlanan anketler incelendi, sonuçlar ve ki- kare testi kullanılarak istatistiksel olarak analiz edildi. Veri analizi, Statistical Package for the Social Sciences 23.0 versiyonu (SPSS Inc., Chicago, ll., ABD) kullanılarak gerçekleştirildi. Bulgular: %95,4’ü çocuk hastada ilk başvurduğu radyografi yönteminin panoramik radyografi ve periapikal radyografi olarak bildirdi. Türk pedodontistlerin % 75,2’ si çocuk hastada KIBT’ nin gerekli olduğunu bildirdi. KIBT’ ye en sık kist tümör vakalarında başvurulduğu bildirildi. Pedodontistlerin %84,8’i KIBT konusunda daha fazla eğitime ihtiyacı olduğunu bildirdi. Sonuç: Türk pedodontistler KIBT’ yi kesinlikle gerekli görmektedirler ve bu konuda eğitime ihtiyaç duymaktadır. Çocuk hastada sıklıkla küçük FOV alanı tercih etmekteler. En sık kist tümör vakalarında KIBT’ ye başvurmaktalar. Anahtar Kelime: Konik Işınlı Bilgisayarlı Tomografi, Pedodonti, Çocuk ABSTRACT Aim: The use and indications of methods that require more radiation dose than conventional imaging methods such as Cone Beam Computed Tomography (CBCT) are still controversial. In this article, it is aimed to evaluate the frequency of the use of CBCT among Turkish pedodontists, their indications and to understand the need for training. Materials and Methods: Two-part questionnaire in an electronic environment was applied to 210 pedodontists to evaluate sociodemographic characteristics and CBCT usage. One part of the questionnaire included questions about the demographic characteristics of pedodontists such as gender and age. In the other section, there were questions about the use of CBCT. The results of the survey were evaluated with the chi-square test. Data analysis was performed using Statistical Package for the Social Sciences version 23.0 (SPSS Inc., Chicago, II., USA). Results: 95.4% reported that panoramic radiography and periapical radiographs were the initial radiologic methods applied in children. 75.2% of Turkish pedodontists reported that CBCT was necessary for a pediatric patient. CBCT was reported to be used most commonly in cases with cyst-tumor. 84.8% of pedodontists reported that they needed more training on CBCT. Conclusions: Turkish pedodontists consider that CBCT is absolutely necessary and they need training on this topic. They often prefer a small FOV area in pediatric patients. They most commonly prefer CBCT in cases of cyst and tumour.
... Cone beam computed tomography (CBCT) has become an important radiographic tool for diagnosis and treatment planning in the field of oral surgery and especially for oral implantology over the last two decades (Bornstein, Horner, Jacobs, 2017;Carter, Stone, Clark, Mercer, 2016). Efficient preoperative diagnostics and surgical treatment planning are necessary to perform successful dental implant insertion and prosthodontic restoration. ...
... CBCT has become a widely accepted radiographic tool for diagnosis and treatment planning in oral implantology, and is also used to assess peri-implant disease (Carter, et al., 2016), and the stability of augmented bone in long-term studies (Chappuis, et al., 2018). This is of relevance, as intraoral radiographs (IR) cannot depict buccal and oral bone loss due to the inherent limitations of 2D imaging (Rees, et al., 1971). ...
Article
Objectives: To investigate the diagnostic accuracy of cone beam computed tomography (CBCT) for the diagnosis of peri-implant bone defects of titanium (Ti), zirconium dioxide (ZrO2 ), or titanium-zirconium (Ti-Zr) alloy implants. Materials and methods: Ti, Ti-Zr or ZrO2 implants with two diameters (3.3 mm, 4.1 mm) and one length (10 mm) were inserted in the angle of the mandible of six fresh defrosted pig jaws. Out of the 12 implants inserted, 6 served in the test group with standardized buccal peri-implant bone defects, whereas 6 served as control without bone defects. CBCTs were performed with three acquisition protocols (standard, high, low dose) using two devices. Four observers analysed CBCTs as follows: 1) presence of a peri-implant defect; 2) presence of peri-implant artefacts and impact on defect diagnosis; 3) linear measurements of buccal peri-implant defect including height and width (in mm). Results: CBCT device, CBCT settings, implant material, implant diameter, and observer background did not significantly influence diagnostic accuracy. The sensitivity and specificity values were high for defect detection. ZrO2 led to a lower than average diagnostic accuracy (0.781). The linear measurements of peri-implant defect were underestimated by <1 mm on average. The subjective impact of artefacts on defect diagnosis was significantly affected by implant material and observer background. Conclusions: CBCT showed high diagnostic accuracy for peri-implant bone defect detection regardless of the device, imaging setting, or implant material used. If CBCT is indicated to assess per-implant bone disease, low dose protocols could be a promising imaging modality.
... CBCT helps mainly in diagnosis and treatment planning in oral implantology [25]. Nowadays, it is also used in different specialties of dentistry like endodontics for prediagnostic analysis of root canal system, additionally dental trauma plus tooth resorption preassessment [26]; in maxillofacial surgery for assessment of maxillary-mandibular-arches pathology, impaction and trauma cases, as well as prediagnostic analysis of implant cases [27]; in orthodontics in prognostics of cleft lip-cleft palate, skeleton malformations, tooth resorption, as well as detection of pathologies in synovial joints, plus alveolar bones [28,29]; finally in periodontics within complicated implant cases involving premolar and molar areas [30]. ...
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Cone Beam Computed Tomography (CBCT) has recently seen an expansion in use, however there are few robust, evidence-based guidelines to inform practitioners. This article reports the case of a large dentigerous cyst in the maxilla affecting the eruption of multiple teeth, considers the use of CBCT in the management of such lesions, and discusses guidelines on the use of CBCT in dentistry. CPD/Clinical Relevance: As CBCT use increases it is important that practitioners understand the guidelines surrounding its use. Due to the prevalence of dentigerous cysts, it is likely that they will be encountered clinically, and it is important that clinicians referring patients with such lesions are familiar with the principles of managing them.
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Objectives To evaluate the diagnostic performance of cone beam computed tomography (CBCT) in the assessment of peri‐implant bone loss and analyze its influencing factors. Materials and Methods Clinical and preclinical studies reporting diagnostic outcomes of CBCT imaging of peri‐implant bone loss compared to direct reference measurements were sought by searching five electronic databases, PubMed, MEDLINE, EMBASE, Web of Science, and CINAHL Plus, and OpenGrey. QUADAS‐2 criteria were adapted for quality analysis of the included studies. A qualitative synthesis was performed. Two meta‐analysis models (random‐effects and mixed‐effects) summarized the area under receiver operating characteristic (AUC) curve observations reported in the selected studies. The mixed‐effects meta‐analysis model evaluated three possible influencing factors, “defect type,” “defect size,” and “study effect.” Results The initial search yielded 3,716 titles, from which 18 studies (13 in vitro and 5 animal) were included. Diagnostic accuracy of CBCT was fair to excellent in detecting in vitro circumferential‐intrabony and fenestration defects, but moderate to low for peri‐implant dehiscences, and tended to be higher for larger defect sizes. Both, over‐ and underestimation of linear measurements were reported for the animal models. The meta‐analyses included 37 AUC observations from eight studies. The random‐effects model showed significant heterogeneity. The mixed‐effects model exhibited also significant but lower heterogeneity, and “defect type” and “study effect” significantly influenced the variability of AUC observations. Conclusion In vitro, CBCT performs well in detecting peri‐implant circumferential‐intrabony or fenestration defects but less in depicting dehiscences. Influencing factors due to other site‐related and technical parameters on the diagnostic outcome need to be addressed further in the future studies.
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Article
Amaç: Bu çalışmanın amacı, bir grup hastada konik ışınlı bilgisayarlı tomografi (KIBT) istem nedenlerini ve bu istemlerin yaş, cinsiyet, istemi yapan bölüm ve istem alanlarına göre dağılımını geriye dönük olarak incelemektir. Yöntem: Arşiv kayıtlarından elde edilen KIBT istek formları geriye dönük olarak değerlendirildi. Yaş, cinsiyet, istemde bulunan bölümler, istem nedenleri ve istem alanları kayıt altına alındı. İstem nedenleri kemik içi lezyon, ortodonti, endodonti, gömülü diş, dental anomali, yumuşak doku kalsifikasyonu, operasyon öncesi, travma, implant cerrahisi, temporomandibular eklem kemik yapısının değerlendirilmesi ve diğer nedenler olarak sınıflandırıldı. İstem yapan bölümler, Ağız, Diş ve Çene Radyolojisi Anabilim Dalı, Ağız Diş Çene Cerrahisi Anabilim Dalı, Ortodonti Anabilim Dalı, Endodonti Anabilim Dalı ve diğerleri olarak sınıflandırıldı. İstem alanları maksilla, mandibula, maksillofasiyal bölge ve tek diş bölgesi olarak sınıflandırıldı. Veriler tanımlayıcı istatistik yöntemleri kullanılarak SPSS ile analiz edildi. Bulgular: Çalışmaya 679 KIBT istemi dahil edildi ve hastaların yaş ortalaması 37,44±17,39 idi. En fazla yapılan istem nedeni kemik içi lezyon değerlendirilmesi (%29,6), en çok KIBT talep eden bölüm Ağız, Diş ve Çene Radyoloji Anabilim Dalı (%51,4) ve en çok talep edilen bölge maksillofasiyal bölge (%52,9) idi. Sonuç: Çalışmanın sonuçları, KIBT görüntülerinin çoğunun kemik içi lezyonun değerlendirilmesi için istendiğini göstermiştir. KIBT 'nin talep nedenlerinin hekimler tarafından değerlendirilmesi ve KIBT 'nin kullanım alanlarının belirlenmesi tekniğin geliştirilmesi açısından faydalı olabilir.
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Accurate segmentation of the jaw (i.e., mandible and maxilla) and the teeth in cone beam computed tomography (CBCT) scans is essential for orthodontic diagnosis and treatment planning. Although various (semi)automated methods have been proposed to segment the jaw or the teeth, there is still a lack of fully automated segmentation methods that can simultaneously segment both anatomic structures in CBCT scans (i.e., multiclass segmentation). In this study, we aimed to train and validate a mixed-scale dense (MS-D) convolutional neural network for multiclass segmentation of the jaw, the teeth, and the background in CBCT scans. Thirty CBCT scans were obtained from patients who had undergone orthodontic treatment. Gold standard segmentation labels were manually created by 4 dentists. As a benchmark, we also evaluated MS-D networks that segmented the jaw or the teeth (i.e., binary segmentation). All segmented CBCT scans were converted to virtual 3-dimensional (3D) models. The segmentation performance of all trained MS-D networks was assessed by the Dice similarity coefficient and surface deviation. The CBCT scans segmented by the MS-D network demonstrated a large overlap with the gold standard segmentations (Dice similarity coefficient: 0.934 ± 0.019, jaw; 0.945 ± 0.021, teeth). The MS-D network–based 3D models of the jaw and the teeth showed minor surface deviations when compared with the corresponding gold standard 3D models (0.390 ± 0.093 mm, jaw; 0.204 ± 0.061 mm, teeth). The MS-D network took approximately 25 s to segment 1 CBCT scan, whereas manual segmentation took about 5 h. This study showed that multiclass segmentation of jaw and teeth was accurate and its performance was comparable to binary segmentation. The MS-D network trained for multiclass segmentation would therefore make patient-specific orthodontic treatment more feasible by strongly reducing the time required to segment multiple anatomic structures in CBCT scans.
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Objective The aim of this study was to construct an anthropomorphic maxillofacial phantom for dental imaging and dosimetry purposes using three-dimensional (3D) printing technology and materials that simulate the radiographic properties of tissues. Methods Stereolithography photoreactive resins, polyurethane rubber and epoxy resin were modified by adding calcium carbonate and strontium carbonate powders or glass bubbles. These additives were used to change the materials’ CT numbers to mimic various body tissues. A maxillofacial phantom was designed using CT images of a head. Results Commercial 3D printing resins were found to have CT numbers near 120 HU and were used to print intervertebral discs and an external skin for the maxillofacial phantom. By adding various amounts of calcium carbonate and strontium carbonate powders the CT number of the resin was raised to 1000 & 1500 HU and used to print bone mimics. Epoxy resin modified by adding glass bubbles was used in assembly and as a cartilaginous mimic. Glass bubbles were added to polyurethane rubber to reduce the CT number to simulate soft tissue and filled spaces between the printed anatomy and external skin of the phantom. Conclusion The maxillofacial phantom designed for dental imaging and dosimetry constructed using 3D printing, polyurethane rubbers and epoxy resins represented a patient anatomically and radiographically. The results of the designed phantom, materials and assembly process can be applied to generate different phantoms that better represent diverse patient types and accommodate different ion chambers.
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Introduction: Cone-beam computed tomographic (CBCT) imaging is an emerging technology for clinical endodontic practice. The aim of this study was to investigate the acceptance, accessibility, and usage of CBCT imaging among American Association of Endodontists members in the United States by means of an online survey. Methods: An invitation to participate in a web-based survey was sent to 3076 members of the American Association of Endodontists. The survey consisted of 8 questions on demographics, access to CBCT machines, field of view (FOV), frequency of use for particular applications, and reasons in case CBCT was not used. Results: A total of 1083 participants completed the survey, giving an overall completed response rate of 35.2%; 80.30% of the participants had access to a CBCT scan, of which 50.69% (n = 443) were on-site and 49.31% (n = 431) were off-site, and 19.30% of all respondents denied having access to CBCT imaging. Limited FOV was used by 55.26% participants, 22.37% used larger FOV formats, and the remaining 22.37% were not sure about the format. There was a significantly greater usage of CBCT technology in residency programs (n = 78/84 [92.86%]) compared with practitioners who had finished an endodontic specialty program (n = 796/999 [79.68%]) (χ(2) = 10.30, P = .02). Practitioners used CBCT imaging "frequent" or "always" for internal or external resorptions (47.28%), preoperatively for surgical retreatment or intentional replantation (45.34%), missing canals (25.39%), preoperatively for nonsurgical retreatments (24.91%), differential diagnosis (21.16%), identifying periradicular lesions (18.26%), calcified cases (13.54%), immature teeth (4.71%), and to assess healing (3.87%). There was a significant difference in on-site and off-site CBCT imaging use for any of these applications (P < .001). Prevalent reasons for not using CBCT technology were cost (53.79%) and lack of installation space (8.29%). General concerns were expressed about resolution limitations, radiation exposure, and cost to the patient. Conclusions: There is a widespread application of CBCT technology in endodontic practice; however, results from the survey also confirmed that the benefit versus risk ratio should always be in favor of the patient if CBCT scans are taken.
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Cone beam CT (CBCT) is becoming an increasingly utilized imaging modality for dental examinations in the UK. Previous studies have presented little information on patient dose for the range of fields of view (FOVs) that can be utilized. The purpose of the study was therefore to calculate the effective dose delivered to the patient during a selection of CBCT examinations performed in dentistry. In particular, the i-CAT CBCT scanner was investigated for several imaging protocols commonly used in clinical practice. A Rando phantom containing thermoluminescent dosemeters was scanned. Using both the 1990 and recently approved 2007 International Commission on Radiological Protection recommended tissue weighting factors, effective doses were calculated. The doses (E(1990), E(2007)) were: full FOV head (92.8 microSv, 206.2 microSv); 13 cm scan of the jaws (39.5 microSv, 133.9 microSv); 6 cm high-resolution mandible (47.2 microSv, 188.5 microSv); 6 cm high-resolution maxilla (18.5 microSv, 93.3 microSv); 6 cm standard mandible (23.9 microSv, 96.2 microSv); and 6 cm standard maxilla (9.7 microSv, 58.9 microSv). The doses from CBCT are low compared with conventional CT but significantly higher than conventional dental radiography techniques.
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With the increasing use of computed tomography (CT) in oral diagnosis and treatment planning, concern has been expressed about the high levels of radiation used, and the associated risks. The purpose of this study was to compare the radiation doses of facial CT scans with the radiation doses taking a lateral cephalometric radiograph, a panoramic radiograph (OPG), an occlusal film, and an intra-oral periapical radiograph. An Alderson-Rando anthropomorphic phantom head was used for the analysis. Thirty-six lithium fluoride thermoluminescent dosimeters were placed in the phantom head in locations representing radiosensitive sites. Standard facial CT scans and conventional radiographs (lateral cephalometric, OPG, maxillary occlusal, intra-oral periapical) were then taken of the phantom head. The following radiation doses were measured: maxillo-mandibular CT scan, 2.1 mSv; maxillary CT scan, 1.40 mSv; mandibular CT scan, 1.32 mSv; lateral cephalometric radiograph, 0.005 mSv; OPG, 0.010 mSv; maxillary occlusal, 0.007 mSv; intra-oral periapical radiograph, 0.005 mSv. CT scans produce significantly more ionising radiation than conventional radiographs. This factor should be taken into account when considering a CT scan as an alternative to a survey with conventional radiographs. While CT scans offer many advantages over conventional radiography the high radiation dose to patients, and the cost of this procedure should be considered.
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Cone beam computed tomography (CBCT), which provides a lower dose, lower cost alternative to conventional CT, is being used with increasing frequency in the practice of oral and maxillofacial radiology. This study provides comparative measurements of effective dose for three commercially available, large (12'') field-of-view (FOV), CBCT units: CB Mercuray, NewTom 3G and i-CAT. Thermoluminescent dosemeters (TLDs) were placed at 24 sites throughout the layers of the head and neck of a tissue-equivalent human skull RANDO phantom. Depending on availability, the 12'' FOV and smaller FOV scanning modes were used with similar phantom positioning geometry for each CBCT unit. Radiation weighted doses to individual organs were summed using 1990 (E(1990)) and proposed 2005 (E(2005 draft)) ICRP tissue weighting factors to calculate two measures of whole-body effective dose. Dose as a multiple of a representative panoramic radiography dose was also calculated. For repeated runs dosimetry was generally reproducible within 2.5%. Calculated doses in microSv [corrected] (E(1990), E(2005 draft)) were NewTom3G (45, 59), i-CAT (135, 193) and CB Mercuray (477, 558). These are 4 to 42 times greater than comparable panoramic examination doses (6.3 microSv [corrected] 13.3 mSv). Reductions in dose were seen with reduction in field size and mA and kV technique factors. CBCT dose varies substantially depending on the device, FOV and selected technique factors. Effective dose detriment is several to many times higher than conventional panoramic imaging and an order of magnitude or more less than reported doses for conventional CT.
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Recent advances in cone beam computed tomography (CBCT) in dentistry have identified the importance of providing outcomes related to the appropriate use of this innovative technology to practitioners, educators, and investigators. To assist in determining whether and what types of evidence exist, the authors conducted PubMed, Google, and Cochrane Library searches in the spring of 2011 using the key words "cone beam computed tomography and dentistry." This search resulted in over 26,900 entries in more than 700 articles including forty-one reviews recently published in national and international journals. This article is based on existing publications and studies and will provide readers with an overview of the advantages, disadvantages, and indications/contraindications of this emerging technology as well as some thoughts on the current educational status of CBCT in U.S. dental schools. It is the responsibility of dental educators to incorporate the most updated information on this technology into their curricula in a timely manner, so that the next generation of oral health providers and educators will be competent in utilizing this technology for the best interest of patients. To do so, there is a need to conduct studies meeting methodological standards to demonstrate the diagnostic efficacy of CBCT in the dental field.
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The advent of extraoral radiology in general dental practice has become more widespread since 2000, particularly with digital systems. With this comes a range of medico-legal risks for dentists not adverted to previously. These risks include a higher than expected radiation dose for some surveys, and the risk of a ‘loss of a chance’ for a patient whereby the images may disclose pathology not diagnosed by general dental practitioners using OPG and CBVT radiology. Practitioners need to apply relevant legal principles in deciding which surveys to order and record, and also need to explain to patients the dosages of the radiation that they will likely receive. Practitioners also need to assess whether the resultant survey ought to be interpreted by a radiologist to diagnose any wider pathology with which a general practitioner may not be familiar. Extra caution needs to be used in ordering high dose radiology in paediatric patients. Dentists should not assume patients fully understand the nature of CBVT and MCT, and its risks and benefits. Consideration ought to be given to the volume of CBVT ordered dependent on factors such as patient age, symptoms, history and procedural intent.
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Cone-beam computed tomography (CBCT) was introduced into the U.S. market in 2001. Today, there are more than 3,000 installed units in the United States. There are numerous CBCT manufacturers and types of units. To produce the best imaging results, clinicians need to be knowledgeable about the CBCT unit, the clinical issue being investigated and how to optimize the unit's operational parameters. The author identifies the variables that should be considered for each imaging session and addresses the building blocks required to design the appropriate imaging strategy. The remaining articles in this supplement address imaging for orthodontics, the investigation and localization of impacted teeth and implant planning, and customized imaging protocols designed to solve the clinical issues being presented. The author addresses CBCT from an operational point of view. An ideal imaging examination answers the clinical question while maintaining an acceptable radiation dose and cost. The quality and value of each imaging study is proportional to the protocol being used. The author also addresses imaging protocol variables (raw data frames, scan time, voxel size, field of view and milliampere settings) and their effects on the final image quality and radiation dose, as well as CBCT accuracy and the radiation dose. CBCT can provide image volumes of the maxillofacial region and can be useful in clinical dentistry. CBCT has been shown to be a precise imaging modality and is a valuable tool for use in dental applications. CBCT can be used for diagnosis and treatment planning for all of the dental specialties.
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To compare the effective dose levels of cone beam computed tomography (CBCT) for maxillofacial applications with those of multi-slice computed tomography (MSCT). The effective doses of 3 CBCT scanners were estimated (Accuitomo 3D, i-CAT, and NewTom 3G) and compared to the dose levels for corresponding image acquisition protocols for 3 MSCT scanners (Somatom VolumeZoom 4, Somatom Sensation 16 and Mx8000 IDT). The effective dose was calculated using thermoluminescent dosimeters (TLDs), placed in a Rando Alderson phantom, and expressed according to the ICRP 103 (2007) guidelines (including a separate tissue weighting factor for the salivary glands, as opposed to former ICRP guidelines). Effective dose values ranged from 13 to 82 microSv for CBCT and from 474 to 1160 microSv for MSCT. CBCT dose levels were the lowest for the Accuitomo 3D, and highest for the i-CAT. Dose levels for CBCT imaging remained far below those of clinical MSCT protocols, even when a mandibular protocol was applied for the latter, resulting in a smaller field of view compared to various CBCT protocols. Considering this wide dose span, it is of outmost importance to justify the selection of each of the aforementioned techniques, and to optimise the radiation dose while achieving a sufficient image quality. When comparing these results to previous dosimetric studies, a conversion needs to be made using the latest ICRP recommendations.
Article
This review article provides an overview of cone beam (CB) imaging technology and its role in orofacial imaging, including comparison with two-dimensional (2D) radiography and multislice computed tomography (MCT). The radiation dose levels of CB systems are discussed, with reference to those delivered by MCT and common dental 2D views. The large variation in dose levels delivered by CB systems and the importance of using ultra low-dose CB units are emphasized. Low-dose MCT protocols can be used. CB and MCT image quality are compared. CB is an essential technique that all dental and orofacial clinicians must be familiar with. Where ultra low-dose systems and protocols are used, CB imaging should be considered in day-to-day clinical practice. However, CB imaging is not the technique of choice in many clinical scenarios. Rather than replacing other modalities, CB imaging complements intraoral 2D radiography, panoramic radiography, MCT and other techniques including magnetic resonance imaging, ultrasound and nuclear medicine. MCT is a much more powerful and flexible modality and presently remains the technique of choice over CB imaging in many clinical scenarios. All radiologic examinations, including CB and MCT, should be comprehensively evaluated in entirety. The responsibilities and the radiological skill levels of clinicians involved in imaging as well as the associated ethical and medico-legal implications require consideration.
Article
Cone beam computed tomography (CBCT) is a diagnostic imaging modality that has shown rapid adoption in clinical dental practice over the past 10 years. CBCT images provide high quality, accurate 3-dimensional (3D) representations of the osseous elements of the maxillofacial skeleton. The purpose of this article is to provide (1) an introduction to maxillofacial CBCT technology, (2) an understanding of the relative patient radiation dose, and (3) to underline the appropriate use of CBCTas a diagnostic imaging modality with specific clinical applications.
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A review of modern imaging techniques commonly used in dental practice and their clinical applications is presented. The current dental examinations consist of intraoral imaging with digital indirect and direct receptors, while extraoral imaging is divided into traditional tomographic/panoramic imaging and the more recently introduced cone beam computed tomography. Applications, limitations and current trends of these dental "in-office" radiographic techniques are discussed.
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Cone beam computed tomography imaging represents a paradigm shift for enhancing diagnosis and treatment planning. Questions regarding cone beam computed tomography's associated legal responsibility are addressed, including cone beam computed tomography necessity, recognition of pathosis in the scan's entire volume, adequate training, informed consent and/or refusal and current court status of cone beam computed tomography. Judicious selection and prudent use of cone beam computed tomography technology to protect and promote patient safety and efficacious treatment complies with the standard of care.
Article
The increasing use of cone-beam computed tomography (CBCT) requires changes in our diagnosis and treatment planning methods as well as additional training. The standard for digital computed tomography images is called digital imaging and communications in medicine (DICOM). In this article we discuss the following concepts: visualization of CBCT images in orthodontics, measurement in CBCT images, creation of 2-dimensional radiographs from DICOM files, segmentation engines and multimodal images, registration and superimposition of 3-dimensional (3D) images, special applications for quantitative analysis, and 3D surgical prediction. CBCT manufacturers and software companies are continually working to improve their products to help clinicians diagnose and plan treatment using 3D craniofacial images.
Article
The study aim was to compare the geometric accuracy of three-dimensional (3D) surface model reconstructions between five Cone Beam Computed Tomography (CBCT) scanners and one Multi-Slice CT (MSCT) system. A dry human mandible was scanned with five CBCT systems (NewTom 3G, Accuitomo 3D, i-CAT, Galileos, Scanora 3D) and one MSCT scanner (Somatom Sensation 16). A 3D surface bone model was created from the six systems. The reference (gold standard) 3D model was obtained with a high resolution laser surface scanner. The 3D models from the five systems were compared with the gold standard using a point-based rigid registration algorithm. The mean deviation from the gold standard for MSCT was 0.137 mm and for CBCT were 0.282, 0.225, 0.165, 0.386 and 0.206 mm for the i-CAT, Accuitomo, NewTom, Scanora and Galileos, respectively. The results show that the accuracy of CBCT 3D surface model reconstructions is somewhat lower but acceptable comparing to MSCT from the gold standard.
Article
To compare image quality and visibility of anatomical structures in the mandible between five Cone Beam Computed Tomography (CBCT) scanners and one Multi-Slice CT (MSCT) system. One dry mandible was scanned with five CBCT scanners (Accuitomo 3D, i-CAT, NewTom 3G, Galileos, Scanora 3D) and one MSCT system (Somatom Sensation 16) using 13 different scan protocols. Visibility of 11 anatomical structures and overall image noise were compared between CBCT and MSCT. Five independent observers reviewed the CBCT and the MSCT images in the three orthographic planes (axial, sagittal and coronal) and assessed image quality on a five-point scale. Significant differences were found in the visibility of the different anatomical structures and image noise level between MSCT and CBCT and among the five CBCT systems (p=0.0001). Delicate structures such as trabecular bone and periodontal ligament were significantly less visible and more variable among the systems in comparison with other anatomical structures (p=0.0001). Visibility of relatively large structures such as mandibular canal and mental foramen was satisfactory for all devices. The Accuitomo system was superior to MSCT and all other CBCT systems in depicting anatomical structures while MSCT was superior to all other CBCT systems in terms of reduced image noise. CBCT image quality is comparable or even superior to MSCT even though some variability exists among the different CBCT systems in depicting delicate structures. Considering the low radiation dose and high-resolution imaging, CBCT could be beneficial for dentomaxillofacial radiology.
Article
To develop "basic principles" on the use of dental cone beam CT by consensus of the membership of the European Academy of Dental and Maxillofacial Radiology. A guideline development panel was formed to develop a set of draft statements using existing European directives and guidelines on radiation protection. These statements were revised after an open debate of attendees at a European Academy of Dental and Maxillofacial Radiology (EADMFR) Congress in June 2008. A modified Delphi procedure was used to present the revised statements to the EADMFR membership, utilising an online survey in October/November 2008. Of the 339 EADMFR members, 282 had valid e-mail addresses and could be alerted to the online survey. A response rate of 71.3% of those contacted by e-mail was achieved. Consensus of EADMFR members, indicated by high level of agreement for all statements, was achieved without a need for further rounds of the Delphi process. A set of 20 basic principles on the use of dental cone beam CT has been devised. They will act as core standards for EADMFR and, it is hoped, will be of value in national standard-setting within Europe.
Article
Volumetric CT using a cone beam has been developed by several manufacturers for dentomaxillofacial imaging. The purpose of this study was to measure doses for implant planning with cone beam volumetric imaging (CBVI) in comparison with conventional multidetector CT (MDCT). The two CBVI systems used were a 3D Accuitomo (J. Morita), including an image-intensifier type (II) and a flat-panel type (FPD), and a CB MercuRay (Hitachi). The 3D Accuitomo operated at 80 kV, 5 mA and 18 s. The CB MercuRay operated at 120 kV, 15 mA, 9.8 s. The MDCT used was a HiSpeed QX/i (GE), operated at 120 kV, 100 mA and 0.7 s, and its scan length was 77 mm for both jaws. Measurement of the absorbed tissue and organ doses was performed with an Alderson phantom, embedding the radiophotoluminescence glass dosemeter into the organs/tissues. The values obtained were converted into the absorbed dose. The effective dose as defined by the International Commission on Radiological Protection was then calculated. The absorbed doses of the 3D Accuitomo of the organs in the primary beam ranged from 1-5 mGy, and were several to ten times lower than other doses. The effective dose of the 3D Accuitomo ranged from 18 muSv to 66 muSv, and was an order of magnitude smaller than the others. In conclusion, these results show that the dose in the 3D Accuitomo is lower than the CB MercuRay and much less than MDCT.
Article
This study provides effective dose measurements for two extraoral direct digital imaging devices, the NewTom 9000 cone beam CT (CBCT) unit and the Orthophos Plus DS panoramic unit. Thermoluminescent dosemeters were placed at 20 sites throughout the layers of the head and neck of a tissue-equivalent RANDO phantom. Variations in phantom orientation and beam collimation were used to create three different CBCT examination techniques: a combined maxillary and mandibular scan (Max/Man), a maxillary scan and a mandibular scan. Ten exposures for each technique were used to ensure a reliable measure of radiation from the dosemeters. Average tissue-absorbed dose, weighted equivalent dose and effective dose were calculated for each major anatomical site. Effective doses of individual organs were summed with salivary gland exposures (E(SAL)) and without salivary gland exposures (E(ICRP60)) to calculate two measures of whole-body effective dose. The effective doses for CBCT were: Max/Man scan, E(ICRP60)=36.3 micro Sv, E(SAL)=77.9 micro Sv; maxillary scan, E(ICRP60)=19.9 micro Sv, E(SAL)=41.5 micro Sv; and mandibular scan, E(ICRP60)=34.7 micro Sv, E(SAL)=74.7 micro Sv. Effective doses for the panoramic examination were E(ICRP60)=6.2 micro Sv and E(SAL)=22.0 micro Sv. When viewed in the context of potential diagnostic yield, the E(ICRP60) of 36.3 micro Sv for the NewTom compares favourably with published effective doses for conventional CT (314 micro Sv) and film tomography (2-9 micro Sv per image). CBCT examinations resulted in doses that were 3-7 (E(ICRP60)) and 2-4 (E(SAL)) times the panoramic doses observed in this study.
Article
The purpose of this investigation was to measure the tissue-absorbed dose and to calculate the effective dose for the NewTom 9000, a new generation of computed tomographic devices designed specifically for dental applications. Comparisons are made with existing reports on dose measurement and effective dose estimates for panoramic examinations and other computed tomographic imaging modalities for dental implants. Thermoluminescent dosimeters were implanted in a tissue-equivalent humanoid phantom at anatomic sites of interest. Absorbed dose measurements were obtained after single and double exposures. The averaged tissue-absorbed doses were used for the calculation of the whole-body effective dose. The effective dose for imaging of maxillomandibular volume with a NewTom 9000 machine is 50.3 muSv. The effective dose with the NewTom 9000 machine is significantly less than that achieved with other computed tomographic imaging methods and is within the range of traditional dental imaging modalities.
Article
(a) To measure the absorbed dose at certain anatomical sites of a RANDO phantom and to estimate the effective dose in radiographic imaging of the jaws using low dose Cone Beam computed tomography (CBCT) and (b) to compare the absorbed and the effective doses between thyroid and cervical spine shielding and non-shielding techniques. Thermoluminescent dosimeters (TLD-100) were placed at 14 sites in a RANDO phantom, using a Cone Beam CT device (Newtom, Model QR-DVT 9000, Verona, Italy). Dosimetry was carried out applying two techniques: in the first, there was no shielding device used while in the second one, a shielding device (EUREKA!, TRIX) was applied for protection of the thyroid gland and the cervical spine. Effective dose was estimated according to ICRP(60) report (E(ICRP)). An additional estimation of the effective dose was accomplished including the doses of the salivary glands (E(SAL)). A Wilcoxon Signed Ranks Test was used for statistical analysis. In the non-shielding technique the absorbed doses ranged from 0.16 to 1.67 mGy, while 0.32 and 1.28 mGy were the doses to the thyroid and the cervical spine, respectively. The effective dose, E(ICRP), was 0.035 mSv and the E(SAL) was 0.064 mSv. In the shielding technique, the absorbed doses ranged from 0.09 to 1.64 mGy, while 0.18 and 0.95 mGy were the respective values for the thyroid and the cervical spine. The effective dose, E(ICRP), was 0.023 mSv and E(SAL) was 0.052 mSv. The use of CBCT for maxillofacial imaging results in a reduced absorbed and effective dose. The use of lead shielding leads to a further reduction of the absorbed doses of thyroid and cervical spine, as well as the effective dose.
Article
CT scanning has become an established diagnostic tool within the radiology department. This article covers some of the history of the development and early days of CT scanning. It is based upon the lecture given on the Memorial Day for Sir Godfrey Hounsfield during the British Institute of Radiology President's Conference 2005.
Article
Cone-beam computed tomography (CBCT) systems have been designed for imaging hard tissues of the maxillofacial region. CBCT is capable of providing sub-millimetre resolution in images of high diagnostic quality, with short scanning times (10-70 seconds) and radiation dosages reportedly up to 15 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 3-dimensional representation of the maxillofacial skeleton with minimal distortion. This article provides an overview of currently available maxillofacial CBCT systems and reviews the specific application of various CBCT display modes to clinical dental practice.
Article
This study evaluates two methods for calculating effective dose, CT dose index (CTDI) and dose-area product (DAP) for a cone beam CT (CBCT) device: 3D Accuitomo at field size 30x40 mm and 3D Accuitomo FPD at field sizes 40x40 mm and 60x60 mm. Furthermore, the effective dose of three commonly used examinations in dental radiology was determined. CTDI(100) measurements were performed in a CT head dose phantom with a pencil ionization chamber connected to an electrometer. The rotation centre was placed in the centre of the phantom and also, to simulate a patient examination, in the upper left cuspid region. The DAP value was determined with a plane-parallel transmission ionization chamber connected to an electrometer. A conversion factor of 0.08 mSv per Gy cm(2) was used to determine the effective dose from DAP values. Based on data from 90 patient examinations, DAP and effective dose were determined. CTDI(100) measurements showed an asymmetric dose distribution in the phantom when simulating a patient examination. Hence a correct value of CTDI(w) could not be calculated. The DAP value increased with higher tube current and tube voltage values. The DAP value was also proportional to the field size. The effective dose was found to be 11-77 microSv for the specific examinations. DAP measurement was found to be the best method for determining effective dose for the Accuitomo. Determination of specific conversion factors in dental radiology must, however, be further developed.
Article
Cone-beam computed tomography (CBCT) has been changing the way dental practitioners use imaging. The radiation dose to the patient and how to effectively reduce the dose is still not completely clear to most users of this technology. The objective of this study was to quantitate the change in radiation dose when using different CBCT settings. A CBCT machine was modified to allow different setting combinations. The variables consisted of 4 different mA choices (2, 5, 10, and 15), 2 kVp choices (100 and 120), and 3 fields of view (6 inches, 9 inches, and 12 inches). A radiation phantom with 10 thermoluminescent dosimeters (TLD) was used to measure radiation dose. One specific setting (15 mA, 120 kVp, and 12-inch FOV) was scanned 3 times to determine consistency. The CBCT showed less than 5% variance in radiation dose values. An overall reduction in dose of about 0.62 times was achieved by reducing the kVp from 120 to 100. When reducing the field size the dose decreased 5% to 10%, while for organs that escaped the direct beam the reduction was far greater. A reduction in radiation dose can be achieved by using the lowest exposure settings and narrow collimation.
Article
Because of the advantages and possibilities of cone-beam computed tomography (CBCT), orthodontists use this method routinely for patient assessment. The aim of this study was to compare the radiation doses for conventional panoramic and cephalometric imaging with the doses for 2 different CBCT units and a multi-slice CT unit in orthodontic practice. The absorbed organ doses were measured by using an anthropomorphic phantom loaded with thermoluminescent dosimeters at 16 sites related to sensitive organs. The 4 devices (Sirona DS Plus [Sirona Dental Systems, Bernsheim, Germany], i-CAT [Imaging Sciences International, Hatfield, Pa], NewTom DVT 9000 [QR, Verona, Italy], and Somatom Sensation [Siemens Medical Solutions, Erlangen, Germany]) were used with standard protocols and, when possible, in the auto-exposure mode. Equivalent and effective doses were calculated. The calculation of the effective doses was based on the International Commission on Radiological Protection's 2005 recommendations. The lowest organ dose (13.1 microSv) was received by the thyroid gland during conventional panoramic and lateral cephalometric imaging. The highest mean organ dose (15,837.2 microSv) was received by the neck skin from the multi-slice CT. The effective dose was also lower for the panoramic and lateral cephalometric device (10.4 microSv), and highest for the multi-slice CT (429.7 microSv). From a radiation-protection point of view, conventional images still deliver the lowest doses to patients. When 3-dimensional imaging is required in orthodontic practice, a CBCT should be preferred over a CT image. Further studies are necessary to justify the routine use of CBCT in orthodontic treatment planning.
Article
This study compares 2 measures of effective dose, E(1990) and E(2007), for 8 dentoalveolar and maxillofacial cone-beam computerized tomography (CBCT) units and a 64-slice multidetector CT (MDCT) unit. Average tissue-absorbed dose, equivalent dose, and effective dose were calculated using thermoluminescent dosimeter chips in a radiation analog dosimetry phantom. Effective doses were derived using 1990 and the superseding 2007 International Commission on Radiological Protection (ICRP) recommendations. Large-field of view (FOV) CBCT E(2007) ranged from 68 to 1,073 microSv. Medium-FOV CBCT E(2007) ranged from 69 to 560 microSv, whereas a similar-FOV MDCT produced 860 microSv. The E(2007) calculations were 23% to 224% greater than E(1990). The 2007 recommendations of the ICRP, which include salivary glands, extrathoracic region, and oral mucosa in the calculation of effective dose, result in an upward reassessment of fatal cancer risk from oral and maxillofacial radiographic examinations. Dental CBCT can be recommended as a dose-sparing technique in comparison with alternative medical CT scans for common oral and maxillofacial radiographic imaging tasks.
Article
This study compares tissue-absorbed and effective doses of the cone beam CT (CBCT) units, the Veraviewepocs 3D and the 3D Accuitomo, in different protocols. The absorbed organ doses were measured using an anthropomorphic phantom loaded with thermoluminescent dosemeters (TLDs) in 16 sensitive organ sites. Both CBCT units were deployed with different fields of view (FOVs): 3D Accuitomo using two protocols (anterior 4 x 4 cm scan and anterior 6 x 6 cm scan) and Veraviewepocs 3D using three protocols (anterior 4 x 4 cm scan, anterior 8 x 4 cm scan and panoramic + anterior 4 x 4 cm). Equivalent and effective doses were then calculated, the latter based on the International Commission on Radiological Protection's (ICRP) 2005 recommendations. The lowest effective dose was observed for the 3D Accuitomo 4 x 4 cm (20.02 microSv), the highest for the 3D Accuitomo 6 x 6 cm (43.27 microSv). The effective dose recorded for Veraviewepocs 3D was 39.92 microSv for the 8 x 4 cm scan, 30.92 microSv for the 4 x 4 cm scan and 29.78 microSv for the panoramic + 4 x 4 cm scan protocol. The radiation doses delivered by both machines were in comparable ranges when using 4 x 4 cm FOV. A smaller FOV should be used for dental images, whereas a larger FOV should be restricted to cases in which a wider view is required.
Article
The aim of this study was to evaluate the effective doses from analog film, panoramic digital, and panoramic scout for cone-beam computerized tomography (CT). Three different types of Veraviewepocs machines were investigated: Veraviewepocs Conventional, Veraviewepocs Digital, and Veraviewepocs 3D (Morita, Kyoto, Japan). Organ absorbed doses were measured using an anthropomorphic phantom loaded with thermoluminescent dosimeters (TLD 100H) at 16 sites located in sensitive organs. The resulting effective organ doses (muSv) were compared by descriptive statistics. The highest value (5.2 muSv) was for Veraviewepocs Conventional. The Veraviewepocs Digital (2.7 muSv) and Veraviewepocs 3D (2.95 muSv) presented low effective doses in the same range. The panoramic digital system delivered the least radiation dose. The use of the panoramic scout for cone-beam CT was marginally higher in dose than its 2D counterpart.
Article
Preliminary evaluation of recently developed large-area flat panel detectors (FPDs) indicates that FPDs have some potential advantages: compactness, absence of geometric distortion and veiling glare with the benefits of high resolution, high detective quantum efficiency (DQE), high frame rate and high dynamic range, small image lag (<1%), and excellent linearity (∼1%). The advantages of the new FPD make it a promising candidate for cone-beam volume computed tomography (CT) angiography (CBVCTA) imaging. The purpose of this study is to characterize a prototype FPD-based imaging system for CBVCTA applications. A prototype FPD-based CBVCTA imaging system has been designed and constructed around a modified GE 8800 CT scanner. This system is evaluated for a CBVCTA imaging task in the head and neck using four phantoms and a frozen rat. The system is first characterized in terms of linearity and dynamic range of the detector. Then, the optimal selection of kVps for CBVCTA is determined and the effect of image lag and scatter on the image quality of the CBVCTA system is evaluated. Next, low-contrast resolution and high-contrast spatial resolution are measured. Finally, the example reconstruction images of a frozen rat are presented. The results indicate that the FPD-based CBVCT can achieve 2.75-1p/mm spatial resolution at 0% modulation transfer function (MTF) and provide more than enough low-contrast resolution for intravenous CBVCTA imaging in the head and neck with clinically acceptable entrance exposure level. The results also suggest that to use an FPD for large cone-angle applications, such as body angiography, further investigations are required.