Objective: To demonstrate optical coherence tomography for high-resolution, noninvasive imaging of the human retina. Optical coherence tomography is a new imaging technique analogous to ultrasound B scan that can provide cross-sectional images of the retina with micrometer-scale resolution. Design: Survey optical coherence tomographic examination of the retina, including the macula and optic nerve head in normal human subjects. Settings Research laboratory. Participants: Convenience sample of normal human subjects. Main Outcome Measures: Correlation of optical coherence retinal tomographs with known normal retinal anatomy. Results: Optical coherence tomographs can discriminate the cross-sectional morphologic features of the fovea and optic disc, the layered structure of the retina, and normal anatomic variations in retinal and retinal nerve fiber layer thicknesses with 10- μm depth resolution. Conclusion: Optical coherence tomography is a potentially useful technique for high depth resolution, cross-sectional examination of the fundus.

Optical Coherence Tomography of the Human Retina

http://www.endoexperience.com/documents/DeVos2009.pdf

Cone-beam computerized tomography (CBCT) imaging of the oral and maxillofacial region: a systematic review of the literature.

https://www.sedentexct.eu/system/files/Pauwels%20EJR_0.pdf

Effective dose range for dental cone beam computed tomography scanners.

Detection and diagnosis of dental caries using a deep learning-based convolutional neural network algorithm.

Background Periodontal diagnosis relies heavily on traditional two-dimensional radiographic assessment. Despite efforts in improving reliability, current methods of detecting bone level changes over time or determining three-dimensional architecture of osseous defects are inadequate. To address these issues, computed tomography (CT) has been explored because of its ability to produce accurate three-dimensional imaging, but limitations such as radiation, machine size, and cost have made this approach impractical. Recently, cone beam computed tomography (CBCT) has turned this concept into potential reality because these lower-cost small machines produce high-quality data. Yet there is little research to establish periodontal bone measurement using CBCT as a valid method. Therefore, the aim of this study was to compare CBCT measurements of periodontal defects to traditional methods. Methods Artificial osseous defects were created on mandibles of dry skulls. CBCT scanning, periapical radiography (PA), and direct measurements using a periodontal probe were compared to an electronic caliper that was used as a standard reference. Results Linear measurements for all defects revealed no statistical differences between bone sounding, radiography, and CBCT. There was a significant difference when comparing isolated interproximal measurements using a probe versus the caliper (P Conclusions Overall, all three modalities are useful for identifying interproximal periodontal defects. Compared to radiographs, the three-dimensional capability of CBCT offers a significant advantage because all defects can be detected and quantified.

/pdf/accuracy-of-cone-beam-computed-tomography-for-periodontal-4kujjklhvs.pdf

Accuracy of cone beam computed tomography for periodontal defect measurements.

As CBCT is widely used in dental and maxillofacial imaging, it is important for users as well as referring practitioners to understand the basic concepts of this imaging modality. This review covers the technical aspects of each part of the CBCT imaging chain. First, an overview is given of the hardware of a CBCT device. The principles of cone beam image acquisition and image reconstruction are described. Optimization of imaging protocols in CBCT is briefly discussed. Finally, basic and advanced visualization methods are illustrated. Certain topics in these review are applicable to all types of radiographic imaging (e.g. the principle and properties of an X-ray tube), others are specific for dental CBCT imaging (e.g. advanced visualization techniques).

/pdf/technical-aspects-of-dental-cbct-state-of-the-art-38in3rf6da.pdf

Technical aspects of dental CBCT: state of the art

Objective: The purpose of this paper is to present the system configuration and physical properties of a new dentomaxillofacial X-ray cone beam CT system (CB MercuRay™) being developed. Methods: The system consists of an image intensifier and a cone beam X-ray source. There are two different models of this system, each with a different size image intensifier, 9″ or 12″. Each system has three field of view (FOV) modes. The 12″ system has facial (F), panoramic (P) and implant (I) FOV modes. The 9″ system has P, I and dental (D) modes. Images produced by these systems consist of 512×512×512 isotropic voxels. Physical properties such as resolution, noise and distortion of the images were evaluated in this study. Modulation transfer function (MTF) was measured using Boone's method. Image noise was measured as the standard deviation of the CT value in water. Circularity of the axial images yielded by the two models was measured using an 8 mm diameter acrylic pipe phantom. Results: The resolving power at a MTF o...

Characteristics of a newly developed dentomaxillofacial X-ray cone beam CT scanner (CB MercuRay™): system configuration and physical properties

Objectives: 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). Methods: 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. R...

https://www.birpublications.org/doi/pdf/10.1259/dmfr/14769929

Absorbed and effective doses from cone beam volumetric imaging for implant planning

Objectives To assess the accuracy of a limited cone-beam volumetric imaging system in detecting incipient proximal caries. Study design Fifty extracted premolars were used. On 100 surfaces examined, 71 proximal carious lesions were found; 47 were limited to the enamel, and 24 penetrated into the dentin. A limited cone-beam volumetric imaging system (CBVI), 3D Accuitomo (J. Morita Mfg. Corp., Kyoto, Japan), was used. Insight films (Eastman Kodak, Rochester, NY) were used for comparison. Seven experienced oral radiologists determined the presence of lesions using a continuous rating scale. The area measure (Az) values were calculated from the receiver operating characteristic curve obtained for each modality and observer. Results The mean Az-values were 0.63 ± 0.02 for 3D Accuitomo and 0.63 ± 0.03 for film. Analysis of variance showed no statistically significant difference between 3D Accuitomo and film. Conclusions A limited CBVI, 3D Accuitomo, could not enhance the accuracy in detecting proximal carious lesions.

Evaluation of a limited cone-beam volumetric imaging system: comparison with film radiography in detecting incipient proximal caries

Objective The study aims at assessing the incidence, course, and characteristics of retromolar canals. Study design The cone-beam computed tomography images of 171 subjects were evaluated for the presence, course, and pattern of occurrence of retromolar canals. Results Three types of retromolar canals namely A, B, & C were detected in 129 subjects. Type A branched off the mandibular canal distal to third molar to open into retomolar fossa, type B coursed between retromolar fossa and radicular portion of third molar, type C coursed from mandibular foramen anteroinferiorly to exit into retromolar fossa. The type B retromolar canal presented features distinguishing it from other types. Conclusions Considerable number of individuals presented with retromolar canals emphasizing their significance in surgeries involving the retromolar area. The type B pattern, to the best of our knowledge, hasn't been reported by most researchers and hence, could be considered as an additional type of retromolar canal.

Kazuyuki Araki

Papers

Technical aspects of dental CBCT: state of the art

Characteristics of a newly developed dentomaxillofacial X-ray cone beam CT scanner (CB MercuRay™): system configuration and physical properties

Absorbed and effective doses from cone beam volumetric imaging for implant planning

Evaluation of a limited cone-beam volumetric imaging system: comparison with film radiography in detecting incipient proximal caries

Retromolar canals as observed on cone-beam computed tomography: their incidence, course, and characteristics