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Sample records for 3d cone beam

  1. Development of an advanced 3D cone beam tomographic system

    Sire, Pascal; Rizo, Philippe; Martin, M.; Grangeat, Pierre; Morisseau, P.

    Due to its high spatial resolution, the 3D X-ray cone-beam tomograph (CT) maximizes understanding of test object microstructure. In order for the present X-ray CT NDT system to control ceramics and ceramic-matrix composites, its spatial resolution must exceed 50 microns. Attention is given to two experimental data reconstructions that have been conducted to illustrate system capabilities.

  2. 3D Cone Beam Volumetric Tomography Dedicated to Maxillofacial Radiology

    Masoud Varshosaz

    2009-01-01

    Full Text Available   "nThe 3D cone beam volume/computed tomography (CBVT/CBCT has been designed for imaging the hard tissues of the maxillofacial region, although it has been used in some era of medical imaging for many years. CBVT is capable of providing a sub-millimeter resolution with the short scanning time of mostly less than 20 seconds and radiation dosages reportedly up to 15 times lower than those of spiral CT scans. In less than a decade, CBVT has revolutionized oral and maxillofacial radiology and is known as the “Standard of Care”. Although development was initially directed towards multiplanar viewing for dental implant and orthodontic treatment planning, secondary applications in other areas continue to expand such as maxillo-facial trauma, temporomandibular joint disorders, sinuse pathosis and upper airway evaluation. The intent of this presentation is to provide an overview of CBVT technology, advantages and disadvantages compared to the other modalities such as 2D images and medical CT and examples of justified cases in the oral & maxillofacial region.   

  3. Practical limitations of cone-beam computed tomography in 3D cephalometry%Practical limitations of cone-beam computed tomography in3D cephalometry

    Janalt Damstra; Zacharias Fourie; Yijin Ren

    2011-01-01

    3D cone beam computed tomography (CBCT) images offer a unique and new appreciation of the anatomical structures and underlying anomalies not possible with conventional radiographs.However,in almost all aspects of CBCT imaging,from utilization to application,inherent limitations and pitfalls exist.Importantly,these inherent limitations and pitfalls have practical implications which need to be addressed before the potential of this technology can be fully realized.The purpose of this review was to explore the current limitations and pitfalls associated with CBCT imaging to allow for better and more accurate understanding of the possibilities this imaging modality could offer,particularly pertaining to 3D cephalometry.

  4. Practical limitations of cone-beam computed tomography in 3D cephalometry

    Damstra, Janalt; Fourie, Zacharias; Ren, Yijin

    2011-01-01

    3D cone beam computed tomography (CBCT) images offer a unique and new appreciation of the anatomical structures and underlying anomalies not possible with conventional radiographs. However, in almost all aspects of CBCT imaging, from utilization to application, inherent limitations and pitfalls exis

  5. 3D analytic cone-beam reconstruction for multiaxial CT acquisitions.

    Yin, Zhye; De Man, Bruno; Pack, Jed

    2009-01-01

    A conventional 3rd generation Computed Tomography (CT) system with a single circular source trajectory is limited in terms of longitudinal scan coverage since extending the scan coverage beyond 40 mm results in significant cone-beam artifacts. A multiaxial CT acquisition is achieved by combining multiple sequential 3rd generation axial scans or by performing a single axial multisource CT scan with multiple longitudinally offset sources. Data from multiple axial scans or multiple sources provide complementary information. For full-scan acquisitions, we present a window-based 3D analytic cone-beam reconstruction algorithm by tessellating data from neighboring axial datasets. We also show that multi-axial CT acquisition can extend the axial scan coverage while minimizing cone-beam artifacts. For half-scan acquisitions, one cannot take advantage of conjugate rays. We propose a cone-angle dependent weighting approach to combine multi-axial half-scan data. We compute the relative contribution from each axial dataset to each voxel based on the X-ray beam collimation, the respective cone-angles, and the spacing between the axial scans. We present numerical experiments to demonstrate that the proposed techniques successfully reduce cone-beam artifacts at very large volumetric coverage.

  6. GPU-Based 3D Cone-Beam CT Image Reconstruction for Large Data Volume

    Xing Zhao

    2009-01-01

    Full Text Available Currently, 3D cone-beam CT image reconstruction speed is still a severe limitation for clinical application. The computational power of modern graphics processing units (GPUs has been harnessed to provide impressive acceleration of 3D volume image reconstruction. For extra large data volume exceeding the physical graphic memory of GPU, a straightforward compromise is to divide data volume into blocks. Different from the conventional Octree partition method, a new partition scheme is proposed in this paper. This method divides both projection data and reconstructed image volume into subsets according to geometric symmetries in circular cone-beam projection layout, and a fast reconstruction for large data volume can be implemented by packing the subsets of projection data into the RGBA channels of GPU, performing the reconstruction chunk by chunk and combining the individual results in the end. The method is evaluated by reconstructing 3D images from computer-simulation data and real micro-CT data. Our results indicate that the GPU implementation can maintain original precision and speed up the reconstruction process by 110–120 times for circular cone-beam scan, as compared to traditional CPU implementation.

  7. [Upper airway's 3D analysis of patients with obstructive sleep apnea using tomographic cone beam].

    Bruwier, A; Poirrier, A L; Limme, M; Poirrier, R

    2014-12-01

    The progress of medical imaging over the last decades has led to a better understanding of the upper airway structure in sleep-disordered patients. The Obstructive Sleep Apnea Syndrome (OSA) is attributed to a functional narrowing of the upper airway, particularly of the oropharynx, during sleep. This narrowing is multifactorial. We have shown that in 60% cases, the maxilla (nasal pyramid) seems too narrow. A mandible retroposition may also play a dominant role in 30% of the cases. Both scenarios can be combined. Cone Beam Computed Tomography (CBCT) is a new medical imaging technique that permits to visualize the upper airway with less ionizing radiation than the conventional scanner. To date, only five authors have performed an upper airway's 3D analysis of sleep apnea patients with cone beam. A better understanding of the affected segment of the upper airway should help refine treatment options.

  8. How accurate are the fusion of cone-beam CT and 3-D stereophotographic images?

    Yasas S N Jayaratne

    Full Text Available BACKGROUND: Cone-beam Computed Tomography (CBCT and stereophotography are two of the latest imaging modalities available for three-dimensional (3-D visualization of craniofacial structures. However, CBCT provides only limited information on surface texture. This can be overcome by combining the bone images derived from CBCT with 3-D photographs. The objectives of this study were 1 to evaluate the feasibility of integrating 3-D Photos and CBCT images 2 to assess degree of error that may occur during the above processes and 3 to identify facial regions that would be most appropriate for 3-D image registration. METHODOLOGY: CBCT scans and stereophotographic images from 29 patients were used for this study. Two 3-D images corresponding to the skin and bone were extracted from the CBCT data. The 3-D photo was superimposed on the CBCT skin image using relatively immobile areas of the face as a reference. 3-D colour maps were used to assess the accuracy of superimposition were distance differences between the CBCT and 3-D photo were recorded as the signed average and the Root Mean Square (RMS error. PRINCIPAL FINDINGS: The signed average and RMS of the distance differences between the registered surfaces were -0.018 (±0.129 mm and 0.739 (±0.239 mm respectively. The most errors were found in areas surrounding the lips and the eyes, while minimal errors were noted in the forehead, root of the nose and zygoma. CONCLUSIONS: CBCT and 3-D photographic data can be successfully fused with minimal errors. When compared to RMS, the signed average was found to under-represent the registration error. The virtual 3-D composite craniofacial models permit concurrent assessment of bone and soft tissues during diagnosis and treatment planning.

  9. Segmentation process significantly influences the accuracy of 3D surface models derived from cone beam computed tomography

    Fourie, Zacharias; Damstra, Janalt; Schepers, Rutger H; Gerrits, Pieter; Ren, Yijin

    2012-01-01

    AIMS: To assess the accuracy of surface models derived from 3D cone beam computed tomography (CBCT) with two different segmentation protocols. MATERIALS AND METHODS: Seven fresh-frozen cadaver heads were used. There was no conflict of interests in this study. CBCT scans were made of the heads and 3D

  10. The influence of the segmentation process on 3D measurements from cone beam computed tomography-derived surface models

    Engelbrecht, Willem P.; Fourie, Zacharias; Damstra, Janalt; Gerrits, Peter O.; Ren, Yijin

    2013-01-01

    To compare the accuracy of linear and angular measurements between cephalometric and anatomic landmarks on surface models derived from 3D cone beam computed tomography (CBCT) with two different segmentation protocols was the aim of this study. CBCT scans were made of cadaver heads and 3D surface mod

  11. Automatic Calibration Method of Voxel Size for Cone-beam 3D-CT Scanning System

    Yang, Min; Liu, Yipeng; Men, Fanyong; Li, Xingdong; Liu, Wenli; Wei, Dongbo

    2013-01-01

    For cone-beam three-dimensional computed tomography (3D-CT) scanning system, voxel size is an important indicator to guarantee the accuracy of data analysis and feature measurement based on 3D-CT images. Meanwhile, the voxel size changes with the movement of the rotary table along X-ray direction. In order to realize the automatic calibration of the voxel size, a new easily-implemented method is proposed. According to this method, several projections of a spherical phantom are captured at different imaging positions and the corresponding voxel size values are calculated by non-linear least square fitting. Through these interpolation values, a linear equation is obtained, which reflects the relationship between the rotary table displacement distance from its nominal zero position and the voxel size. Finally, the linear equation is imported into the calibration module of the 3D-CT scanning system, and when the rotary table is moving along X-ray direction, the accurate value of the voxel size is dynamically expo...

  12. Analysis of bite marks in foodstuffs by computer tomography (cone beam CT)--3D reconstruction.

    Marques, Jeidson; Musse, Jamilly; Caetano, Catarina; Corte-Real, Francisco; Corte-Real, Ana Teresa

    2013-12-01

    The use of three-dimensional (3D) analysis of forensic evidence is highlighted in comparison with traditional methods. This three-dimensional analysis is based on the registration of the surface from a bitten object. The authors propose to use Cone Beam Computed Tomography (CBCT), which is used in dental practice, in order to study the surface and interior of bitten objects and dental casts of suspects. In this study, CBCT is applied to the analysis of bite marks in foodstuffs, which may be found in a forensic case scenario. 6 different types of foodstuffs were used: chocolate, cheese, apple, chewing gum, pizza and tart (flaky pastry and custard). The food was bitten into and dental casts of the possible suspects were made. The dental casts and bitten objects were registered using an x-ray source and the CBCT equipment iCAT® (Pennsylvania, EUA). The software InVivo5® (Anatomage Inc, EUA) was used to visualize and analyze the tomographic slices and 3D reconstructions of the objects. For each material an estimate of its density was assessed by two methods: HU values and specific gravity. All the used materials were successfully reconstructed as good quality 3D images. The relative densities of the materials in study were compared. Amongst the foodstuffs, the chocolate had the highest density (median value 100.5 HU and 1,36 g/cm(3)), while the pizza showed to have the lowest (median value -775 HU and 0,39 g/cm(3)), on both scales. Through tomographic slices and three-dimensional reconstructions it was possible to perform the metric analysis of the bite marks in all the foodstuffs, except for the pizza. These measurements could also be obtained from the dental casts. The depth of the bite mark was also successfully determined in all the foodstuffs except for the pizza. Cone Beam Computed Tomography has the potential to become an important tool for forensic sciences, namely for the registration and analysis of bite marks in foodstuffs that may be found in a crime

  13. 3D Quantification of Mandibular Asymmetry through Cone Beam Computed Tomography

    Cevidanes, Lucia H.S.; Alhadidi, Abeer; Paniagua, Beatriz; Styner, Martin; Ludlow, John; Mol, Andre; Turvey, Timothy; Proffit, William R.; Rossouw, Paul Emile

    2011-01-01

    Objective To determine if 3D shape analysis precisely diagnoses right and left differences in asymmetry patients Study Design Cone-beam CT data was acquired pretreatment from 20 patients with mandibular asymmetry. 3D shape analysis was used to localize and quantify the extent of virtually simulated asymmetry. Two approaches were used: (1) mirroring on the midsagittal plane determined from landmarks and (2) mirroring on an arbitrary plane, then registering on the cranial base of the original image. The validation presented in this study used simulated data and has been applied to three clinical cases. Results For mirroring on the midsagittal plane there was a >99% probability that the difference between measured and simulated asymmetry was less than 0.5 mm. For mirroring with cranial base registration, there was a >84% probability of differences less than 0.5 mm. Conclusions Mandibular asymmetry can be precisely quantified with both mirroring methods. Cranial base registration has the potential to be used for patients with trauma situations or when key landmarks are unreliable or absent. PMID:21497527

  14. Image quality of a cone beam O-arm 3D imaging system

    Zhang, Jie; Weir, Victor; Lin, Jingying; Hsiung, Hsiang; Ritenour, E. Russell

    2009-02-01

    The O-arm is a cone beam imaging system designed primarily to support orthopedic surgery and is also used for image-guided and vascular surgery. Using a gantry that can be opened or closed, the O-arm can function as a 2-dimensional (2D) fluoroscopy device or collect 3-dimensional (3D) volumetric imaging data like a CT system. Clinical applications of the O-arm in spine surgical procedures, assessment of pedicle screw position, and kyphoplasty procedures show that the O-arm 3D mode provides enhanced imaging information compared to radiographs or fluoroscopy alone. In this study, the image quality of an O-arm system was quantitatively evaluated. A 20 cm diameter CATPHAN 424 phantom was scanned using the pre-programmed head protocols: small/medium (120 kVp, 100 mAs), large (120 kVp, 128 mAs), and extra-large (120 kVp, 160 mAs) in 3D mode. High resolution reconstruction mode (512×512×0.83 mm) was used to reconstruct images for the analysis of low and high contrast resolution, and noise power spectrum. MTF was measured using the point spread function. The results show that the O-arm image is uniform but with a noise pattern which cannot be removed by simply increasing the mAs. The high contrast resolution of the O-arm system was approximately 9 lp/cm. The system has a 10% MTF at 0.45 mm. The low-contrast resolution cannot be decided due to the noise pattern. For surgery where locations of a structure are emphasized over a survey of all image details, the image quality of the O-arm is well accepted clinically.

  15. A cone-beam CT based technique to augment the 3D virtual skull model with a detailed dental surface.

    Swennen, G.R.; Mommaerts, M.Y.; Abeloos, J.V.S.; Clercq, C. De; Lamoral, P.; Neyt, N.; Casselman, J.W.; Schutyser, F.A.C.

    2009-01-01

    Cone-beam computed tomography (CBCT) is used for maxillofacial imaging. 3D virtual planning of orthognathic and facial orthomorphic surgery requires detailed visualisation of the interocclusal relationship. This study aimed to introduce and evaluate the use of a double CBCT scan procedure with a mod

  16. Detectability of hepatic tumors during 3D post-processed ultrafast cone-beam computed tomography

    Paul, Jijo; Vogl, Thomas J.; Chacko, Annamma

    2015-10-01

    To evaluate hepatic tumor detection using ultrafast cone-beam computed tomography (UCBCT) cross-sectional and 3D post-processed image datasets. 657 patients were examined using UCBCT during hepatic transarterial chemoembolization (TACE), and data were collected retrospectively from January 2012 to September 2014. Tumor detectability, diagnostic ability, detection accuracy and sensitivity were examined for different hepatic tumors using UCBCT cross-sectional, perfusion blood volume (PBV) and UCBCT-MRI (magnetic resonance imaging) fused image datasets. Appropriate statistical tests were used to compare collected sample data. Fused image data showed the significantly higher (all P  color display. Fused image data produced 100% tumor sensitivity due to the simultaneous availability of MRI and UCBCT information during tumor diagnosis. Fused image data produced excellent hepatic tumor sensitivity, detectability and diagnostic ability compared to other datasets assessed. Fused image data is extremely reliable and useful compared to UCBCT cross-sectional or PBV image datasets to depict hepatic tumors during TACE. Partial anatomical visualization on cross-sectional images was compensated by fused image data during tumor diagnosis.

  17. A new cone-beam computed tomography system for dental applications with innovative 3D software

    Pasini, Alessandro; Bianconi, D.; Rossi, A. [University of Bologna, Department of Physics, Bologna (Italy); NECTAR Imaging srl Imola (Italy); Casali, F. [University of Bologna, Department of Physics, Bologna (Italy); Bontempi, M. [CEFLA Dental Group Imola (Italy)

    2007-02-15

    Objective Cone beam computed tomography (CBCT) is an important image technique for oral surgery (dentoalveolar surgery and dental implantology) and maxillofacial applications. This technique requires compact sized scanners with a relatively low radiation dosage, which makes them suitable for imaging of the craniofacial region. This article aims to present the concept and the preliminary findings obtained with the prototype of a new CBCT scanner with dedicated 3D software, specifically designed for dental imaging. Methods The prototype implements an X-ray tube with a nominal focal spot of 0.5 mm operating at 70-100 kVp and 1-4 mA. The detector is a 6 in. image intensifier coupled with a digital CCD camera. Dosimetry was performed on a RANDO anthropomorphic phantom using Beryllium Oxide thermo-luminescent dosimeters positioned in the phantom in the following site: eyes, thyroid, skin (lips, cheeks, back of the neck), brain, mandible, maxilla and parotid glands. Doses were measured using four configurations, changing the field-of-view (4'' and 6'') and acquisition time (10 and 20 s) of the CBCT. Acquisitions were performed with different parameters regarding the x-ray tube, pixel size and acquisition geometries to evaluate image quality in relation to modulation transfer function (MTF), noise and geometric accuracy. Results The prototype was able to acquire a complete maxillofacial scan in 10-15 s. The CT reconstruction algorithm delivered images that were judged to have high quality, allowing for precise volume rendering. The radiation dose was determined to be 1-1.5 times that of the dose applied during conventional dental panoramic studies. Conclusion Preliminary studies using the CBCT prototype indicate that this device provides images with acceptable diagnostic content at a relatively low radiation dosage, if compared to systems currently available on the market. (orig.)

  18. 3D localization of electrophysiology catheters from a single x-ray cone-beam projection

    Robert, Normand, E-mail: normand.robert@sri.utoronto.ca; Polack, George G.; Sethi, Benu; Rowlands, John A. [Physical Sciences, Sunnybrook Research Institute, 2075 Bayview Avenue, Toronto, Ontario M4N 3M5 (Canada); Crystal, Eugene [Division of Cardiology, Sunnybrook Health Sciences Centre, 2075 Bayview Avenue, Toronto, Ontario M4N 3M5 (Canada)

    2015-10-15

    Purpose: X-ray images allow the visualization of percutaneous devices such as catheters in real time but inherently lack depth information. The provision of 3D localization of these devices from cone beam x-ray projections would be advantageous for interventions such as electrophysiology (EP), whereby the operator needs to return a device to the same anatomical locations during the procedure. A method to achieve real-time 3D single view localization (SVL) of an object of known geometry from a single x-ray image is presented. SVL exploits the change in the magnification of an object as its distance from the x-ray source is varied. The x-ray projection of an object of interest is compared to a synthetic x-ray projection of a model of said object as its pose is varied. Methods: SVL was tested with a 3 mm spherical marker and an electrophysiology catheter. The effect of x-ray acquisition parameters on SVL was investigated. An independent reference localization method was developed to compare results when imaging a catheter translated via a computer controlled three-axes stage. SVL was also performed on clinical fluoroscopy image sequences. A commercial navigation system was used in some clinical image sequences for comparison. Results: SVL estimates exhibited little change as x-ray acquisition parameters were varied. The reproducibility of catheter position estimates in phantoms denoted by the standard deviations, (σ{sub x}, σ{sub y}, σ{sub z}) = (0.099 mm,  0.093 mm,  2.2 mm), where x and y are parallel to the detector plane and z is the distance from the x-ray source. Position estimates (x, y, z) exhibited a 4% systematic error (underestimation) when compared to the reference method. The authors demonstrated that EP catheters can be tracked in clinical fluoroscopic images. Conclusions: It has been shown that EP catheters can be localized in real time in phantoms and clinical images at fluoroscopic exposure rates. Further work is required to characterize

  19. Self-calibration of cone-beam CT geometry using 3D-2D image registration

    Ouadah, S.; Stayman, J. W.; Gang, G. J.; Ehtiati, T.; Siewerdsen, J. H.

    2016-04-01

    Robotic C-arms are capable of complex orbits that can increase field of view, reduce artifacts, improve image quality, and/or reduce dose; however, it can be challenging to obtain accurate, reproducible geometric calibration required for image reconstruction for such complex orbits. This work presents a method for geometric calibration for an arbitrary source-detector orbit by registering 2D projection data to a previously acquired 3D image. It also yields a method by which calibration of simple circular orbits can be improved. The registration uses a normalized gradient information similarity metric and the covariance matrix adaptation-evolution strategy optimizer for robustness against local minima and changes in image content. The resulting transformation provides a ‘self-calibration’ of system geometry. The algorithm was tested in phantom studies using both a cone-beam CT (CBCT) test-bench and a robotic C-arm (Artis Zeego, Siemens Healthcare) for circular and non-circular orbits. Self-calibration performance was evaluated in terms of the full-width at half-maximum (FWHM) of the point spread function in CBCT reconstructions, the reprojection error (RPE) of steel ball bearings placed on each phantom, and the overall quality and presence of artifacts in CBCT images. In all cases, self-calibration improved the FWHM—e.g. on the CBCT bench, FWHM  =  0.86 mm for conventional calibration compared to 0.65 mm for self-calibration (p  <  0.001). Similar improvements were measured in RPE—e.g. on the robotic C-arm, RPE  =  0.73 mm for conventional calibration compared to 0.55 mm for self-calibration (p  <  0.001). Visible improvement was evident in CBCT reconstructions using self-calibration, particularly about high-contrast, high-frequency objects (e.g. temporal bone air cells and a surgical needle). The results indicate that self-calibration can improve even upon systems with presumably accurate geometric calibration and is

  20. Development of a fully 3D system model in iterative expectation-maximization reconstruction for cone-beam SPECT

    Ye, Hongwei; Vogelsang, Levon; Feiglin, David H.; Lipson, Edward D.; Krol, Andrzej

    2008-03-01

    In order to improve reconstructed image quality for cone-beam collimator SPECT, we have developed and implemented a fully 3D reconstruction, using an ordered subsets expectation maximization (OSEM) algorithm, along with a volumetric system model - cone-volume system model (CVSM), a modified attenuation compensation, and a 3D depth- and angle-dependent resolution and sensitivity correction. SPECT data were acquired in a 128×128 matrix, in 120 views with a single circular orbit. Two sets of numerical Defrise phantoms were used to simulate CBC SPECT scans, and low noise and scatter-free projection datasets were obtained using the SimSET Monte Carlo package. The reconstructed images, obtained using OSEM with a line-length system model (LLSM) and a 3D Gaussian post-filter, and OSEM with FVSM and a 3D Gaussian post-filter were quantitatively studied. Overall improvement in the image quality has been observed, including better transaxial resolution, higher contrast-to-noise ratio between hot and cold disks, and better accuracy and lower bias in OSEM-CVSM, compared with OSEM-LLSM.

  1. Imagens em 2D e 3D geradas pela TC Cone-Beam e radiografias convencionais: qual a mais confiável? 2D / 3D Cone-Beam CT images or conventional radiography: which is more reliable?

    Carolina Perez Couceiro

    2010-10-01

    Full Text Available OBJETIVO: comparar a confiabilidade de identificação dos pontos visualizados sobre radiografias cefalométricas convencionais e sobre imagens geradas pela Tomografia Computadorizada Cone-Beam em 2D e 3D. MÉTODOS: o material constou de imagens obtidas através do tomógrafo computadorizado Cone-Beam, em norma lateral, em 2D e 3D, impressas em papel fotográfico; e radiografias cefalométricas laterais, realizadas na mesma clínica radiológica e no mesmo dia, de dois pacientes pertencentes aos arquivos do Curso de Especialização em Ortodontia da Faculdade de Odontologia da Universidade Federal Fluminense (UFF. Dez alunos do Curso de Especialização em Ortodontia da UFF identificaram pontos de referência sobre papel de acetato transparente e foram feitas medições das seguintes variáveis cefalométricas: ANB, FMIA, IMPA, FMA, ângulo interincisal, 1-NA (mm e ¯1-NB (mm. Em seguida, foram calculadas médias aritméticas, desvios-padrão e coeficientes de variância de cada variável para os dois pacientes. RESULTADOS E CONCLUSÃO: os valores das medições realizadas a partir de imagens em 3D apresentaram menor dispersão, sugerindo que essas imagens são mais confiáveis quanto à identificação de alguns pontos cefalométricos. Entretanto, como as imagens em 3D impressas utilizadas no presente estudo não permitiram a visualização de pontos intracranianos, torna-se necessário que softwares específicos sejam elaborados para que esse tipo de exame possa se tornar rotineiro na clínica ortodôntica.OBJECTIVE: To compare the reliability of two different methods used for viewing and identifying cephalometric landmarks, i.e., (a using conventional cephalometric radiographs, and (b using 2D and 3D images generated by Cone-Beam Computed Tomography. METHODS: The material consisted of lateral view 2D and 3D images obtained by Cone-Beam Computed Tomography printed on photo paper, and lateral cephalometric radiographs, taken in the same

  2. 3D Nondestructive Visualization and Evaluation of TRISO Particles Distribution in HTGR Fuel Pebbles Using Cone-Beam Computed Tomography

    Gongyi Yu

    2017-01-01

    Full Text Available A nonuniform distribution of tristructural isotropic (TRISO particles within a high-temperature gas-cooled reactor (HTGR pebble may lead to excessive thermal gradients and nonuniform thermal expansion during operation. If the particles are closely clustered, local hotspots may form, leading to excessive stresses on particle layers and an increased probability of particle failure. Although X-ray digital radiography (DR is currently used to evaluate the TRISO distributions in pebbles, X-ray DR projection images are two-dimensional in nature, which would potentially miss some details for 3D evaluation. This paper proposes a method of 3D visualization and evaluation of the TRISO distribution in HTGR pebbles using cone-beam computed tomography (CBCT: first, a pebble is scanned on our high-resolution CBCT, and 2D cross-sectional images are reconstructed; secondly, all cross-sectional images are restructured to form the 3D model of the pebble; then, volume rendering is applied to segment and display the TRISO particles in 3D for visualization and distribution evaluation. For method validation, several pebbles were scanned and the 3D distributions of the TRISO particles within the pebbles were produced. Experiment results show that the proposed method provides more 3D than DR, which will facilitate pebble fabrication research and production quality control.

  3. Optical cone beam tomography of Cherenkov-mediated signals for fast 3D dosimetry of x-ray photon beams in water

    Glaser, Adam K., E-mail: Adam.K.Glaser@dartmouth.edu, E-mail: Brian.W.Pogue@dartmouth.edu; Andreozzi, Jacqueline M. [Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire 03755 (United States); Zhang, Rongxiao [Department of Physics and Astronomy, Dartmouth College, Hanover, New Hampshire 03755 (United States); Pogue, Brian W., E-mail: Adam.K.Glaser@dartmouth.edu, E-mail: Brian.W.Pogue@dartmouth.edu [Thayer School of Engineering and Department of Physics and Astronomy, Dartmouth College, Hanover, New Hampshire 03755 (United States); Gladstone, David J. [Norris Cotton Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire 03766 (United States)

    2015-07-15

    Purpose: To test the use of a three-dimensional (3D) optical cone beam computed tomography reconstruction algorithm, for estimation of the imparted 3D dose distribution from megavoltage photon beams in a water tank for quality assurance, by imaging the induced Cherenkov-excited fluorescence (CEF). Methods: An intensified charge-coupled device coupled to a standard nontelecentric camera lens was used to tomographically acquire two-dimensional (2D) projection images of CEF from a complex multileaf collimator (MLC) shaped 6 MV linear accelerator x-ray photon beam operating at a dose rate of 600 MU/min. The resulting projections were used to reconstruct the 3D CEF light distribution, a potential surrogate of imparted dose, using a Feldkamp–Davis–Kress cone beam back reconstruction algorithm. Finally, the reconstructed light distributions were compared to the expected dose values from one-dimensional diode scans, 2D film measurements, and the 3D distribution generated from the clinical Varian ECLIPSE treatment planning system using a gamma index analysis. A Monte Carlo derived correction was applied to the Cherenkov reconstructions to account for beam hardening artifacts. Results: 3D light volumes were successfully reconstructed over a 400 × 400 × 350 mm{sup 3} volume at a resolution of 1 mm. The Cherenkov reconstructions showed agreement with all comparative methods and were also able to recover both inter- and intra-MLC leaf leakage. Based upon a 3%/3 mm criterion, the experimental Cherenkov light measurements showed an 83%–99% pass fraction depending on the chosen threshold dose. Conclusions: The results from this study demonstrate the use of optical cone beam computed tomography using CEF for the profiling of the imparted dose distribution from large area megavoltage photon beams in water.

  4. Twin robotic x-ray system for 2D radiographic and 3D cone-beam CT imaging

    Fieselmann, Andreas; Steinbrener, Jan; Jerebko, Anna K.; Voigt, Johannes M.; Scholz, Rosemarie; Ritschl, Ludwig; Mertelmeier, Thomas

    2016-03-01

    In this work, we provide an initial characterization of a novel twin robotic X-ray system. This system is equipped with two motor-driven telescopic arms carrying X-ray tube and flat-panel detector, respectively. 2D radiographs and fluoroscopic image sequences can be obtained from different viewing angles. Projection data for 3D cone-beam CT reconstruction can be acquired during simultaneous movement of the arms along dedicated scanning trajectories. We provide an initial evaluation of the 3D image quality based on phantom scans and clinical images. Furthermore, initial evaluation of patient dose is conducted. The results show that the system delivers high image quality for a range of medical applications. In particular, high spatial resolution enables adequate visualization of bone structures. This system allows 3D X-ray scanning of patients in standing and weight-bearing position. It could enable new 2D/3D imaging workflows in musculoskeletal imaging and improve diagnosis of musculoskeletal disorders.

  5. Use of cone-beam CT and live 3-D needle guidance to facilitate percutaneous nephrostomy and nephrolithotripsy access in children and adolescents

    Hawkins, C.M. [Emory University School of Medicine, Department of Radiology and Imaging Sciences, Atlanta, GA (United States); Kukreja, Kamlesh [Texas Children' s Hospital, Department of Radiology, Houston, TX (United States); Singewald, Timothy; Johnson, Neil D.; Racadio, John M. [Cincinnati Children' s Hospital Medical Center, Department of Radiology, Cincinnati, OH (United States); Minevich, Eugene; Reddy, Pramod [Cincinnati Children' s Hospital Medical Center, Department of Urology, Cincinnati, OH (United States)

    2016-04-15

    Gaining access into non-dilated renal collecting systems for percutaneous nephrolithotripsy, particularly in patients with prohibitive body habitus and/or scoliosis, is often challenging using conventional techniques. To evaluate the feasibility of cone-beam CT for percutaneous nephrostomy placement for subsequent percutaneous nephrolithotripsy in children and adolescents. A retrospective review of percutaneous nephrostomy revealed use of cone-beam CT and 3-D guidance in 12 percutaneous nephrostomy procedures for 9 patients between 2006 and 2015. All cone-beam CT-guided percutaneous nephrostomies were for pre-lithotripsy access and all 12 were placed in non-dilated collecting systems. Technical success was 100%. There were no complications. Cone-beam CT with 3-D guidance is a technically feasible technique for percutaneous nephrostomy in children and adolescents, specifically for nephrolithotripsy access in non-dilated collecting systems. (orig.)

  6. A proposed method for accurate 3D analysis of cochlear implant migration using fusion of cone beam CT

    Guido eDees

    2016-01-01

    Full Text Available IntroductionThe goal of this investigation was to compare fusion of sequential cone beam CT volumes to the gold standard (fiducial registration in order to be able to analyze clinical CI migration with high accuracy in three dimensions. Materials and MethodsPaired time-lapsed cone beam CT volumes were performed on five human cadaver temporal bones and one human subject. These volumes were fused using 3D Slicer 4 and BRAINSFit software. Using a gold standard fiducial technique, the accuracy, robustness and performance time of the fusion process were assessed.Results This proposed fusion protocol achieves a sub voxel mean Euclidean distance of 0.05 millimeter in human cadaver temporal bones and 0.16 millimeter when applied to the described in vivo human synthetic data set in over 95% of all fusions. Performance times are less than two minutes.ConclusionHere a new and validated method based on existing techniques is described which could be used to accurately quantify migration of cochlear implant electrodes.

  7. 3D algebraic iterative reconstruction for cone-beam x-ray differential phase-contrast computed tomography.

    Fu, Jian; Hu, Xinhua; Velroyen, Astrid; Bech, Martin; Jiang, Ming; Pfeiffer, Franz

    2015-01-01

    Due to the potential of compact imaging systems with magnified spatial resolution and contrast, cone-beam x-ray differential phase-contrast computed tomography (DPC-CT) has attracted significant interest. The current proposed FDK reconstruction algorithm with the Hilbert imaginary filter will induce severe cone-beam artifacts when the cone-beam angle becomes large. In this paper, we propose an algebraic iterative reconstruction (AIR) method for cone-beam DPC-CT and report its experiment results. This approach considers the reconstruction process as the optimization of a discrete representation of the object function to satisfy a system of equations that describes the cone-beam DPC-CT imaging modality. Unlike the conventional iterative algorithms for absorption-based CT, it involves the derivative operation to the forward projections of the reconstructed intermediate image to take into account the differential nature of the DPC projections. This method is based on the algebraic reconstruction technique, reconstructs the image ray by ray, and is expected to provide better derivative estimates in iterations. This work comprises a numerical study of the algorithm and its experimental verification using a dataset measured with a three-grating interferometer and a mini-focus x-ray tube source. It is shown that the proposed method can reduce the cone-beam artifacts and performs better than FDK under large cone-beam angles. This algorithm is of interest for future cone-beam DPC-CT applications.

  8. A cone-beam CT based technique to augment the 3D virtual skull model with a detailed dental surface.

    Swennen, G R J; Mommaerts, M Y; Abeloos, J; De Clercq, C; Lamoral, P; Neyt, N; Casselman, J; Schutyser, F

    2009-01-01

    Cone-beam computed tomography (CBCT) is used for maxillofacial imaging. 3D virtual planning of orthognathic and facial orthomorphic surgery requires detailed visualisation of the interocclusal relationship. This study aimed to introduce and evaluate the use of a double CBCT scan procedure with a modified wax bite wafer to augment the 3D virtual skull model with a detailed dental surface. The impressions of the dental arches and the wax bite wafer were scanned for ten patient separately using a high resolution standardized CBCT scanning protocol. Surface-based rigid registration using ICP (iterative closest points) was used to fit the virtual models on the wax bite wafer. Automatic rigid point-based registration of the wax bite wafer on the patient scan was performed to implement the digital virtual dental arches into the patient's skull model. Probability error histograms showed errors of wax bite wafer to set-up a 3D virtual augmented model of the skull with detailed dental surface.

  9. 3D weighting in cone beam image reconstruction algorithms: ray-driven vs. pixel-driven.

    Tang, Xiangyang; Nilsen, Roy A; Smolin, Alex; Lifland, Ilya; Samsonov, Dmitry; Taha, Basel

    2008-01-01

    A 3D weighting scheme have been proposed previously to reconstruct images at both helical and axial scans in stat-of-the-art volumetric CT scanners for diagnostic imaging. Such a 3D weighting can be implemented in the manner of either ray-driven or pixel-drive, depending on the available computation resources. An experimental study is conducted in this paper to evaluate the difference between the ray-driven and pixel-driven implementations of the 3D weighting from the perspective of image quality, while their computational complexity is analyzed theoretically. Computer simulated data and several phantoms, such as the helical body phantom and humanoid chest phantom, are employed in the experimental study, showing that both the ray-driven and pixel-driven 3D weighting provides superior image quality for diagnostic imaging in clinical applications. With the availability of image reconstruction engine at increasing computational power, it is believed that the pixel-driven 3D weighting will be dominantly employed in state-of-the-art volumetric CT scanners over clinical applications.

  10. High-quality 3D correction of ring and radiant artifacts in flat panel detector-based cone beam volume CT imaging.

    Anas, Emran Mohammad Abu; Kim, Jae Gon; Lee, Soo Yeol; Hasan, Md Kamrul

    2011-10-07

    The use of an x-ray flat panel detector is increasingly becoming popular in 3D cone beam volume CT machines. Due to the deficient semiconductor array manufacturing process, the cone beam projection data are often corrupted by different types of abnormalities, which cause severe ring and radiant artifacts in a cone beam reconstruction image, and as a result, the diagnostic image quality is degraded. In this paper, a novel technique is presented for the correction of error in the 2D cone beam projections due to abnormalities often observed in 2D x-ray flat panel detectors. Template images are derived from the responses of the detector pixels using their statistical properties and then an effective non-causal derivative-based detection algorithm in 2D space is presented for the detection of defective and mis-calibrated detector elements separately. An image inpainting-based 3D correction scheme is proposed for the estimation of responses of defective detector elements, and the responses of the mis-calibrated detector elements are corrected using the normalization technique. For real-time implementation, a simplification of the proposed off-line method is also suggested. Finally, the proposed algorithms are tested using different real cone beam volume CT images and the experimental results demonstrate that the proposed methods can effectively remove ring and radiant artifacts from cone beam volume CT images compared to other reported techniques in the literature.

  11. A comparative evaluation of Cone Beam Computed Tomography (CBCT) and Multi-Slice CT (MSCT). Part II: On 3D model accuracy

    Liang, X.; Lambrichts, I.; Sun, Y.; Denis, K.; Hassan, B.; Li, L.; Pauwels, R.; Jacobs, R.

    2010-01-01

    Aim: 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. Materials and methods: A dry human mandible was scanned with five CBCT systems (NewTom 3G,

  12. Linearity of patient positioning detection. A phantom study of skin markers, cone beam computed tomography, and 3D ultrasound

    Ballhausen, Hendrik; Hieber, Sheila; Li, Minglun; Belka, Claus; Reiner, Michael [University Hospital of LMU, Department of Radiation Oncology, Munich (Germany); Parodi, Katia [Ludwig-Maximilian-University, Department of Experimental Physics - Medical Physics, Munich (Germany)

    2015-05-01

    Three-dimensional ultrasound (3D-US) is a modality complementary to kilovoltage cone beam computed tomography (kV-CBCT) and skin markers for patient positioning detection. This study compares the linearity of evaluations based on measurements using a modern 3D-US system (Elekta Clarity {sup registered}; Elekta, Stockholm, Sweden), a kV-CBCT system (Elekta iView {sup registered}), and skin markers. An investigator deliberately displaced a multimodal phantom by up to ± 30 mm along different axes. The following data points were acquired: 27 along the lateral axis, 29 along the longitudinal axis, 27 along the vertical axis, and 27 along the space diagonal. At each of these 110 positions, the displacements according to skin' markers were recorded and scans were performed using both 3D-US and kV-CBCT. Shifts were detected by matching bony anatomy or soft tissue density to a reference planning CT in the case of kV-CBCT and for 3D-US, by matching ultrasound volume data to a reference planning volume. A consensus value was calculated from the average of the four modalities. With respect to this consensus value, the linearity (offset and regression coefficient, i.e., slope), average offset, systematic error, and random error of all four modalities were calculated for each axis. Linearity was similar for all four modalities, with regression coefficients between 0.994 and 1.012, and all offsets below 1 mm. The systematic errors of skin markers and 3D-US were higher than for kV-CBCT, but random errors were similar. In particular, 3D-US demonstrated an average offset of 0.36 mm to the right, 0.08 mm inferiorly, and 0.15 mm anteriorly; the systematic error was 0.36 mm laterally, 0.35 mm longitudinally, and 0.22 mm vertically; the random error was 0.15 mm laterally, 0.30 mm longitudinally, and 0.12 mm vertically. A total of 109 out of 110 (99 %) 3D-US measurements were within 1 mm of the consensus value on either axis. The linearity of 3D-US was no worse than that of skin

  13. A comparative evaluation of Cone Beam Computed Tomography (CBCT) and Multi-Slice CT (MSCT). Part II: On 3D model accuracy

    Liang Xin, E-mail: Xin.Liang@med.kuleuven.b [Oral Imaging Centre, School of Dentistry, Oral Pathology and Maxillofacial Surgery, Faculty of Medicine, Catholic University of Leuven (Belgium); College of Stomatology, Dalian Medical University (China); Lambrichts, Ivo, E-mail: Ivo.Lambrichts@uhasselt.b [Department of Basic Medical Sciences, Histology and Electron Microscopy, Faculty of Medicine, University of Hasselt, Diepenbeek (Belgium); Sun Yi, E-mail: Sunyihello@hotmail.co [Oral Imaging Centre, School of Dentistry, Oral Pathology and Maxillofacial Surgery, Faculty of Medicine, Catholic University of Leuven (Belgium); Denis, Kathleen, E-mail: kathleen.denis@groept.b [Department of Industrial Sciences and Techology-Engineering (IWT), XIOS Hogeschool Limburg, Hasselt (Belgium); Hassan, Bassam, E-mail: b.hassan@acta.n [Department of Oral Radiology, Academic Centre for Dentistry Amsterdam (ACTA), Amsterdam (Netherlands); Li Limin, E-mail: Limin.Li@uz.kuleuven.b [Department of Paediatric Dentistry and Special Dental Care, School of Dentistry, Oral Pathology and Maxillofacial Surgery, Faculty of Medicine, Catholic University of Leuven (Belgium); Pauwels, Ruben, E-mail: Ruben.Pauwels@med.kuleuven.b [Oral Imaging Centre, School of Dentistry, Oral Pathology and Maxillofacial Surgery, Faculty of Medicine, Catholic University of Leuven (Belgium); Jacobs, Reinhilde, E-mail: Reinhilde.Jacobs@uz.kuleuven.b [Oral Imaging Centre, School of Dentistry, Oral Pathology and Maxillofacial Surgery, Faculty of Medicine, Catholic University of Leuven (Belgium)

    2010-08-15

    Aim: 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. Materials and methods: 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. Results: 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. Conclusion: The results show that the accuracy of CBCT 3D surface model reconstructions is somewhat lower but acceptable comparing to MSCT from the gold standard.

  14. Comparative evaluation of the accuracy of linear measurements between cone beam computed tomography and 3D microtomography

    Francesca Mangione

    2013-09-01

    Full Text Available OBJECTIVE: The aim of this study was to evaluate the influence of artifacts on the accuracy of linear measurements estimated with a common cone beam computed tomography (CBCT system used in dental clinical practice, by comparing it with microCT system as standard reference. MATERIALS AND METHODS: Ten bovine bone cylindrical samples containing one implant each, able to provide both points of reference and image quality degradation, have been scanned by CBCT and microCT systems. Thanks to the software of the two systems, for each cylindrical sample, two diameters taken at different levels, by using implants different points as references, have been measured. Results have been analyzed by ANOVA and a significant statistically difference has been found. RESULTS AND DISCUSSION: Due to the obtained results, in this work it is possible to say that the measurements made with the two different instruments are still not statistically comparable, although in some samples were obtained similar performances and therefore not statistically significant. CONCLUSION: With the improvement of the hardware and software of CBCT systems, in the near future the two instruments will be able to provide similar performances.

  15. Comparative evaluation of a novel 3D segmentation algorithm on in-treatment radiotherapy cone beam CT images

    Price, Gareth; Moore, Chris

    2007-03-01

    Image segmentation and delineation is at the heart of modern radiotherapy, where the aim is to deliver as high a radiation dose as possible to a cancerous target whilst sparing the surrounding healthy tissues. This, of course, requires that a radiation oncologist dictates both where the tumour and any nearby critical organs are located. As well as in treatment planning, delineation is of vital importance in image guided radiotherapy (IGRT): organ motion studies demand that features across image databases are accurately segmented, whilst if on-line adaptive IGRT is to become a reality, speedy and correct target identification is a necessity. Recently, much work has been put into the development of automatic and semi-automatic segmentation tools, often using prior knowledge to constrain some grey level, or derivative thereof, interrogation algorithm. It is hoped that such techniques can be applied to organ at risk and tumour segmentation in radiotherapy. In this work, however, we make the assumption that grey levels do not necessarily determine a tumour's extent, especially in CT where the attenuation coefficient can often vary little between cancerous and normal tissue. In this context we present an algorithm that generates a discontinuity free delineation surface driven by user placed, evidence based support points. In regions of sparse user supplied information, prior knowledge, in the form of a statistical shape model, provides guidance. A small case study is used to illustrate the method. Multiple observers (between 3 and 7) used both the presented tool and a commercial manual contouring package to delineate the bladder on a serially imaged (10 cone beam CT volumes ) prostate patient. A previously presented shape analysis technique is used to quantitatively compare the observer variability.

  16. 3D terahertz beam profiling

    Pedersen, Pernille Klarskov; Strikwerda, Andrew; Wang, Tianwu

    2013-01-01

    We present a characterization of THz beams generated in both a two-color air plasma and in a LiNbO3 crystal. Using a commercial THz camera, we record intensity images as a function of distance through the beam waist, from which we extract 2D beam profiles and visualize our measurements into 3D beam...

  17. Motion and positional error correction for cone beam 3D-reconstruction with mobile C-arms.

    Bodensteiner, C; Darolti, C; Schumacher, H; Matthäus, L; Schweikard, A

    2007-01-01

    CT-images acquired by mobile C-arm devices can contain artefacts caused by positioning errors. We propose a data driven method based on iterative 3D-reconstruction and 2D/3D-registration to correct projection data inconsistencies. With a 2D/3D-registration algorithm, transformations are computed to align the acquired projection images to a previously reconstructed volume. In an iterative procedure, the reconstruction algorithm uses the results of the registration step. This algorithm also reduces small motion artefacts within 3D-reconstructions. Experiments with simulated projections from real patient data show the feasibility of the proposed method. In addition, experiments with real projection data acquired with an experimental robotised C-arm device have been performed with promising results.

  18. Fusion of cone-beam CT and 3D photographic images for soft tissue simulation in maxillofacial surgery

    Chung, Soyoung; Kim, Joojin; Hong, Helen

    2016-03-01

    During maxillofacial surgery, prediction of the facial outcome after surgery is main concern for both surgeons and patients. However, registration of the facial CBCT images and 3D photographic images has some difficulties that regions around the eyes and mouth are affected by facial expressions or the registration speed is low due to their dense clouds of points on surfaces. Therefore, we propose a framework for the fusion of facial CBCT images and 3D photos with skin segmentation and two-stage surface registration. Our method is composed of three major steps. First, to obtain a CBCT skin surface for the registration with 3D photographic surface, skin is automatically segmented from CBCT images and the skin surface is generated by surface modeling. Second, to roughly align the scale and the orientation of the CBCT skin surface and 3D photographic surface, point-based registration with four corresponding landmarks which are located around the mouth is performed. Finally, to merge the CBCT skin surface and 3D photographic surface, Gaussian-weight-based surface registration is performed within narrow-band of 3D photographic surface.

  19. Influence of Head Motion on the Accuracy of 3D Reconstruction with Cone-Beam CT: Landmark Identification Errors in Maxillofacial Surface Model

    Song, Jin-Myoung; Cho, Jin-Hyoung

    2016-01-01

    Purpose The purpose of this study was to investigate the influence of head motion on the accuracy of three-dimensional (3D) reconstruction with cone-beam computed tomography (CBCT) scan. Materials and Methods Fifteen dry skulls were incorporated into a motion controller which simulated four types of head motion during CBCT scan: 2 horizontal rotations (to the right/to the left) and 2 vertical rotations (upward/downward). Each movement was triggered to occur at the start of the scan for 1 second by remote control. Four maxillofacial surface models with head motion and one control surface model without motion were obtained for each skull. Nine landmarks were identified on the five maxillofacial surface models for each skull, and landmark identification errors were compared between the control model and each of the models with head motion. Results Rendered surface models with head motion were similar to the control model in appearance; however, the landmark identification errors showed larger values in models with head motion than in the control. In particular, the Porion in the horizontal rotation models presented statistically significant differences (P CBCT scan might cause landmark identification errors on the 3D surface model in relation to the direction of the scanner rotation. Clinicians should take this into consideration to prevent patient movement during CBCT scan, particularly horizontal movement. PMID:27065238

  20. 3D cone-beam CT guidance, a novel technique in renal biopsy - results in 41 patients with suspected renal masses

    Braak, Sicco J.; Heesewijk, Johannes P.M. van; Strijen, Marco J.L. van [St Antonius Hospital, Department of Radiology, PO Box 2500, Nieuwegein (Netherlands); Melick, Harm H.E. van; Onaca, Mircea G. [St Antonius Hospital, Department of Urology, Nieuwegein (Netherlands)

    2012-11-15

    To determine whether 3D cone-beam computed tomography (CBCT) guidance allows safe and accurate biopsy of suspected small renal masses (SRM), especially in hard-to-reach anatomical locations. CBCT guidance was used to perform 41 stereotactic biopsy procedures of lesions that were inaccessible for ultrasound guidance or CT guidance. In CBCT guidance, a 3D-volume data set is acquired by rotating a C-arm flat-panel detector angiosystem around the patient. In the data set, a needle trajectory is determined and, after co-registration, a fusion image is created from fluoroscopy and a slice from the data set, enabling the needle to be positioned in real time. Of the 41 lesions, 22 were malignant, 17 were benign, and 2 were nondiagnostic. The two nondiagnostic lesions proved to be renal cell carcinoma. There was no growth during follow-up imaging of the benign lesions (mean 29 months). This resulted in a sensitivity, specificity, PPV, NPV, and accuracy of 91.7, 100, 100, 89.5, and 95.1%, respectively. Mean dose-area product value was 44.0 Gy.cm{sup 2} (range 16.5-126.5). There was one minor bleeding complication. With CBCT guidance, safe and accurate biopsy of a suspected SRM is feasible, especially in hard-to-reach locations of the kidney. (orig.)

  1. Axial 3D region of interest reconstruction using weighted cone beam BPF/DBPF algorithm cascaded with adequately oriented orthogonal butterfly filtering

    Tang, Shaojie; Tang, Xiangyang

    2016-03-01

    Axial cone beam (CB) computed tomography (CT) reconstruction is still the most desirable in clinical applications. As the potential candidates with analytic form for the task, the back projection-filtration (BPF) and the derivative backprojection filtered (DBPF) algorithms, in which Hilbert filtering is the common algorithmic feature, are originally derived for exact helical and axial reconstruction from CB and fan beam projection data, respectively. These two algorithms have been heuristically extended for axial CB reconstruction via adoption of virtual PI-line segments. Unfortunately, however, streak artifacts are induced along the Hilbert filtering direction, since these algorithms are no longer accurate on the virtual PI-line segments. We have proposed to cascade the extended BPF/DBPF algorithm with orthogonal butterfly filtering for image reconstruction (namely axial CB-BPP/DBPF cascaded with orthogonal butterfly filtering), in which the orientation-specific artifacts caused by post-BP Hilbert transform can be eliminated, at a possible expense of losing the BPF/DBPF's capability of dealing with projection data truncation. Our preliminary results have shown that this is not the case in practice. Hence, in this work, we carry out an algorithmic analysis and experimental study to investigate the performance of the axial CB-BPP/DBPF cascaded with adequately oriented orthogonal butterfly filtering for three-dimensional (3D) reconstruction in region of interest (ROI).

  2. Influence of Head Motion on the Accuracy of 3D Reconstruction with Cone-Beam CT: Landmark Identification Errors in Maxillofacial Surface Model.

    Kyung-Min Lee

    Full Text Available The purpose of this study was to investigate the influence of head motion on the accuracy of three-dimensional (3D reconstruction with cone-beam computed tomography (CBCT scan.Fifteen dry skulls were incorporated into a motion controller which simulated four types of head motion during CBCT scan: 2 horizontal rotations (to the right/to the left and 2 vertical rotations (upward/downward. Each movement was triggered to occur at the start of the scan for 1 second by remote control. Four maxillofacial surface models with head motion and one control surface model without motion were obtained for each skull. Nine landmarks were identified on the five maxillofacial surface models for each skull, and landmark identification errors were compared between the control model and each of the models with head motion.Rendered surface models with head motion were similar to the control model in appearance; however, the landmark identification errors showed larger values in models with head motion than in the control. In particular, the Porion in the horizontal rotation models presented statistically significant differences (P < .05. Statistically significant difference in the errors between the right and left side landmark was present in the left side rotation which was opposite direction to the scanner rotation (P < .05.Patient movement during CBCT scan might cause landmark identification errors on the 3D surface model in relation to the direction of the scanner rotation. Clinicians should take this into consideration to prevent patient movement during CBCT scan, particularly horizontal movement.

  3. Trabecular bone structure parameters from 3D image processing of clinical multi-slice and cone-beam computed tomography data

    Klintstroem, Eva; Smedby, Oerjan [Linkoeping University, Center for Medical Image Science and Visualization (CMIV), Linkoeping (Sweden); UHL County Council of Oestergoetland, Department of Radiology, Linkoeping (Sweden); Linkoeping University, Department of Medical and Health Sciences (IMH)/Radiology, Linkoeping (Sweden); Moreno, Rodrigo [Linkoeping University, Center for Medical Image Science and Visualization (CMIV), Linkoeping (Sweden); Linkoeping University, Department of Medical and Health Sciences (IMH)/Radiology, Linkoeping (Sweden); Brismar, Torkel B. [KUS Huddinge, Department of Clinical Science, Intervention and Technology at Karolinska Institutet and Department of Radiology, Stockholm (Sweden)

    2014-02-15

    Bone strength depends on both mineral content and bone structure. The aim of this in vitro study was to develop a method of quantitatively assessing trabecular bone structure by applying three-dimensional image processing to data acquired with multi-slice and cone-beam computed tomography using micro-computed tomography as a reference. Fifteen bone samples from the radius were examined. After segmentation, quantitative measures of bone volume, trabecular thickness, trabecular separation, trabecular number, trabecular nodes, and trabecular termini were obtained. The clinical machines overestimated bone volume and trabecular thickness and underestimated trabecular nodes and number, but cone-beam CT to a lesser extent. Parameters obtained from cone beam CT were strongly correlated with μCT, with correlation coefficients between 0.93 and 0.98 for all parameters except trabecular termini. The high correlation between cone-beam CT and micro-CT suggest the possibility of quantifying and monitoring changes of trabecular bone microarchitecture in vivo using cone beam CT. (orig.)

  4. Influence of object location in cone beam computed tomography (NewTom 5G and 3D Accuitomo 170) on gray value measurements at an implant site

    Parsa, A.; Ibrahim, N.; Hassan, B.; van der Stelt, P.; Wismeijer, D.

    2014-01-01

    Objectives The aim of this study was to determine the gray value variation at an implant site with different object location within the selected field of view (FOV) in two cone beam computed tomography (CBCT) scanners. Methods A 1-cm-thick section from the edentulous region of a dry human mandible w

  5. BEAMS3D Neutral Beam Injection Model

    McMillan, Matthew; Lazerson, Samuel A.

    2014-09-01

    With the advent of applied 3D fields in Tokamaks and modern high performance stellarators, a need has arisen to address non-axisymmetric effects on neutral beam heating and fueling. We report on the development of a fully 3D neutral beam injection (NBI) model, BEAMS3D, which addresses this need by coupling 3D equilibria to a guiding center code capable of modeling neutral and charged particle trajectories across the separatrix and into the plasma core. Ionization, neutralization, charge-exchange, viscous slowing down, and pitch angle scattering are modeled with the ADAS atomic physics database. Elementary benchmark calculations are presented to verify the collisionless particle orbits, NBI model, frictional drag, and pitch angle scattering effects. A calculation of neutral beam heating in the NCSX device is performed, highlighting the capability of the code to handle 3D magnetic fields. Notice: this manuscript has been authored by Princeton University under Contract Number DE-AC02-09CH11466 with the US Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes.

  6. Novel utilization of 3D technology and the hybrid operating theatre: Peri-operative assessment of posterior sterno-clavicular dislocation using cone beam CT

    Crowhurst, James A; Campbell, Douglas; Whitby, Mark; Pathmanathan, Pavthrun

    2013-01-01

    A patient with a medial and posterior dislocation of the right sterno-clavicular (SC) joint and displacement of the trachea and brachiocephalic artery by the medial head of the clavicle underwent general anaesthetic in the operating theatre for an open reduction procedure. The surgeon initially attempted a closed reduction, but this required imaging to check SC alignment. The patient was transferred to an adjacent hybrid operating theatre for imaging. Cone beam computed tomography (CBCT) was performed, which successfully demonstrated a significant reduction in the dislocation of the SC joint. The trachea and brachiocephalic artery were no longer compressed or displaced. This case study demonstrates an alternative to the patient being transferred to the medical imaging department for multi-slice CT. It also describes a novel use of the hybrid operating theatre and its CBCT capabilities. PMID:26229610

  7. Novel utilization of 3D technology and the hybrid operating theatre: Peri-operative assessment of posterior sterno-clavicular dislocation using cone beam CT

    Crowhurst, James A; Campbell, Douglas; Whitby, Mark; Pathmanathan, Pavthrun [The Prince Charles Hospital, Rode Road, Chermside, Queensland (Australia)

    2013-06-15

    A patient with a medial and posterior dislocation of the right sterno-clavicular (SC) joint and displacement of the trachea and brachiocephalic artery by the medial head of the clavicle underwent general anaesthetic in the operating theatre for an open reduction procedure. The surgeon initially attempted a closed reduction, but this required imaging to check SC alignment. The patient was transferred to an adjacent hybrid operating theatre for imaging. Cone beam computed tomography (CBCT) was performed, which successfully demonstrated a significant reduction in the dislocation of the SC joint. The trachea and brachiocephalic artery were no longer compressed or displaced. This case study demonstrates an alternative to the patient being transferred to the medical imaging department for multi-slice CT. It also describes a novel use of the hybrid operating theatre and its CBCT capabilities.

  8. Using cone-beam CT as a low-dose 3D imaging technique for the extremities: initial experience in 50 subjects

    Huang, Ambrose J.; Chang, Connie Y.; Palmer, William E. [Massachusetts General Hospital, Department of Radiology, Division of Musculoskeletal Imaging and Intervention, Boston, MA (United States); Thomas, Bijoy J. [Universal College of Medical Sciences, Department of Radiology, Bhairahawa (Nepal); MacMahon, Peter J. [Mater Misericordiae University Hospital, Department of Radiology, Dublin 7 (Ireland)

    2015-06-01

    To prospectively evaluate a dedicated extremity cone-beam CT (CBCT) scanner in cases with and without orthopedic hardware by (1) comparing its imaging duration and image quality to those of radiography and multidetector CT (MDCT) and (2) comparing its radiation dose to that of MDCT. Written informed consent was obtained for all subjects for this IRB-approved, HIPAA-compliant study. Fifty subjects with (1) fracture of small bones, (2) suspected intraarticular fracture, (3) fracture at the site of complex anatomy, or (4) a surgical site difficult to assess with radiography alone were recruited and scanned on an extremity CBCT scanner prior to FDA approval. Same-day radiographs were performed in all subjects. Some subjects also underwent MDCT within 1 month of CBCT. Imaging duration and image quality were compared between CBCT and radiographs. Imaging duration, effective radiation dose, and image quality were compared between CBCT and MDCT. Fifty-one CBCT scans were performed in 50 subjects. Average imaging duration was shorter for CBCT than radiographs (4.5 min vs. 6.6 min, P = 0.001, n = 51) and MDCT (7.6 min vs. 10.9 min, P = 0.01, n = 7). Average estimated effective radiation dose was less for CBCT than MDCT (0.04 mSv vs. 0.13 mSv, P = 0.02, n = 7). CBCT images yielded more diagnostic information than radiographs in 23/51 cases and more diagnostic information than MDCT in 1/7 cases, although radiographs were superior for detecting hardware complications. CBCT performs high-resolution imaging of the extremities using less imaging time than radiographs and MDCT and lower radiation dose than MDCT. (orig.)

  9. 3D curved multiplanar cone beam CT reconstruction for intracochlear position assessment of straight electrodes array. A temporal bone and clinical study.

    De Seta, D; Mancini, P; Russo, F Y; Torres, R; Mosnier, I; Bensimon, J L; De Seta, E; Heymann, D; Sterkers, O; Bernardeschi, D; Nguyen, Y

    2016-12-01

    A retrospective review of post-op cone beam CT (CBCT) of 8 adult patients and 14 fresh temporal bones that underwent cochlear implantation with straight flexible electrodes array was performed to determine if the position of a long and flexible electrodes array within the cochlear scalae could be reliably assessed with CBCT. An oto-radiologist and two otologists examined the images and assessed the electrodes position. The temporal bone specimens underwent histological analysis for confirm the exact position. The position of the electrodes was rated as scala tympani, scala vestibule, or intermediate position for the electrodes at 180°, 360° and for the apical electrode. In the patient group, for the electrodes at 180° all observers agreed for scala tympani position except for 1 evaluation, while a discrepancy in 3 patients both for the 360° and for the apical electrode assessment were found. In five temporal bones the evaluations were in discrepancy for the 180° electrode, while at 360° a disagreement between raters on the scalar positioning was seen in six temporal bones. A higher discrepancy between was found in assessment of the scalar position of the apical electrode (average pairwise agreement 45.4%, Fleiss k = 0.13). A good concordance was found between the histological results and the consensus between raters for the electrodes in the basal turn, while low agreement (Cohen's k 0.31, pairwise agreement 50%) was found in the identification of the apical electrode position confirming the difficulty to correct identify the electrode position in the second cochlear turn in temporal bones. In conclusion, CBCT is a reliable radiologic exam to correctly evaluate the position of a lateral wall flexible array in implanted patients using the proposed imaging reconstruction method, while some artefacts impede exact evaluation of the position of the apical electrode in temporal bone and other radiological techniques should be preferred in ex vivo studies.

  10. Self-calibration of cone-beam CT geometry using 3D-2D image registration: development and application to tasked-based imaging with a robotic C-arm

    Ouadah, S.; Stayman, J. W.; Gang, G.; Uneri, A.; Ehtiati, T.; Siewerdsen, J. H.

    2015-03-01

    Purpose: Robotic C-arm systems are capable of general noncircular orbits whose trajectories can be driven by the particular imaging task. However obtaining accurate calibrations for reconstruction in such geometries can be a challenging problem. This work proposes a method to perform a unique geometric calibration of an arbitrary C-arm orbit by registering 2D projections to a previously acquired 3D image to determine the transformation parameters representing the system geometry. Methods: Experiments involved a cone-beam CT (CBCT) bench system, a robotic C-arm, and three phantoms. A robust 3D-2D registration process was used to compute the 9 degree of freedom (DOF) transformation between each projection and an existing 3D image by maximizing normalized gradient information with a digitally reconstructed radiograph (DRR) of the 3D volume. The quality of the resulting "self-calibration" was evaluated in terms of the agreement with an established calibration method using a BB phantom as well as image quality in the resulting CBCT reconstruction. Results: The self-calibration yielded CBCT images without significant difference in spatial resolution from the standard ("true") calibration methods (p-value >0.05 for all three phantoms), and the differences between CBCT images reconstructed using the "self" and "true" calibration methods were on the order of 10-3 mm-1. Maximum error in magnification was 3.2%, and back-projection ray placement was within 0.5 mm. Conclusion: The proposed geometric "self" calibration provides a means for 3D imaging on general noncircular orbits in CBCT systems for which a geometric calibration is either not available or not reproducible. The method forms the basis of advanced "task-based" 3D imaging methods now in development for robotic C-arms.

  11. MTF characterization in 2D and 3D for a high resolution, large field of view flat panel imager for cone beam CT

    Shah, Jainil; Mann, Steve D.; Tornai, Martin P.; Richmond, Michelle; Zentai, George

    2014-03-01

    The 2D and 3D modulation transfer functions (MTFs) of a custom made, large 40x30cm2 area, 600- micron CsI-TFT based flat panel imager having 127-micron pixellation, along with the micro-fiber scintillator structure, were characterized in detail using various techniques. The larger area detector yields a reconstructed FOV of 25cm diameter with an 80cm SID in CT mode. The MTFs were determined with 1x1 (intrinsic) binning. The 2D MTFs were determined using a 50.8 micron tungsten wire and a solid lead edge, and the 3D MTF was measured using a custom made phantom consisting of three nearly orthogonal 50.8 micron tungsten wires suspended in an acrylic cubic frame. The 2D projection data was reconstructed using an iterative OSC algorithm using 16 subsets and 5 iterations. As additional verification of the resolution, along with scatter, the Catphan® phantom was also imaged and reconstructed with identical parameters. The measured 2D MTF was ~4% using the wire technique and ~1% using the edge technique at the 3.94 lp/mm Nyquist cut-off frequency. The average 3D MTF measured along the wires was ~8% at the Nyquist. At 50% MTF, the resolutions were 1.2 and 2.1 lp/mm in 2D and 3D, respectively. In the Catphan® phantom, the 1.7 lp/mm bars were easily observed. Lastly, the 3D MTF measured on the three wires has an observed 5.9% RMSD, indicating that the resolution of the imaging system is uniform and spatially independent. This high performance detector is integrated into a dedicated breast SPECT-CT imaging system.

  12. 锥束CT系统的3D Shepp-Logan体模仿真及其投影数据重建%The simulation and projection data reconstruction on 3D Shepp-Logan phantom for cone-beam CT system

    曹涵; 胡战利; 方方; 胡信菊

    2014-01-01

    In order to verify the performance of cone-beam CT imaging algorithm, 3D Shepp-Logan phantom produced by For-tran is presented as the reference model for algorithm performance verification, and introduces the parameter of 3D Shepp-Logan phantom and programming method detailedly. Then, we put it in the projection process directly and get the projection data. Fin-ally, simulation experiments of 3D medical image reconstruction are carried out by the projection data. After experimental veri-fication, it is shown that the performance of the algorithms verifying through 3D Shepp-Logan phantom produced by Fortran is accurate and feasible.%为了验证锥束CT成像算法的性能,提出了使用Fortran语言编写的3D Shepp-Logan体模作为算法性能验证的参考模型,并详细介绍了3D Shepp-Logan体模的参数设置及编程方法。然后,直接加入到正投影程序中得到投影数据。最后,利用得到的投影数据进行了三维医学图像重建的仿真实验。经过实验验证,表明了使用Fortran语言编写的3D Shepp-Logan体模来验证算法性能是准确可行的。

  13. Cone beam computed tomography use in orthodontics.

    Nervina, J M

    2012-03-01

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

  14. 3D face recognition with asymptotic cones based principal curvatures

    Tang, Yinhang

    2015-05-01

    The classical curvatures of smooth surfaces (Gaussian, mean and principal curvatures) have been widely used in 3D face recognition (FR). However, facial surfaces resulting from 3D sensors are discrete meshes. In this paper, we present a general framework and define three principal curvatures on discrete surfaces for the purpose of 3D FR. These principal curvatures are derived from the construction of asymptotic cones associated to any Borel subset of the discrete surface. They describe the local geometry of the underlying mesh. First two of them correspond to the classical principal curvatures in the smooth case. We isolate the third principal curvature that carries out meaningful geometric shape information. The three principal curvatures in different Borel subsets scales give multi-scale local facial surface descriptors. We combine the proposed principal curvatures with the LNP-based facial descriptor and SRC for recognition. The identification and verification experiments demonstrate the practicability and accuracy of the third principal curvature and the fusion of multi-scale Borel subset descriptors on 3D face from FRGC v2.0.

  15. Superposição automatizada de modelos tomográficos tridimensionais em cirurgia ortognática Superimposition of 3D cone-beam CT models in orthognathic surgery

    Alexandre Trindade Simões da Motta

    2010-04-01

    Full Text Available INTRODUÇÃO: as limitações na avaliação quantitativa e qualitativa de deslocamentos cirúrgicos pelos métodos bidimensionais podem ser superadas através de tomografias volumétricas e ferramentas de imagens tridimensionais. OBJETIVOS: a metodologia descrita neste trabalho permite avaliar as mudanças nas posições de côndilos, ramos, mento, maxila e da dentição após a cirurgia ortognática através de tomografias computadorizadas de feixe cônico (Cone Beam Computed Tomography, CBCT antes e após o procedimento cirúrgico. MÉTODOS: são construídos modelos 3D que possibilitam superposições tendo a base do crânio pré-cirúrgica como referência, utilizando-se um método automático que identifica e compara a escala de cinza dos voxels de duas estruturas tridimensionais, eliminando a necessidade do operador marcar os pontos anatômicos. Então, as distâncias entre as superfícies anatômicas são computadas, no mesmo indivíduo, entre as duas fases. A avaliação das direções de deslocamento das estruturas é determinada visualmente pelos métodos de mapas coloridos e de semitransparências. CONCLUSÕES: conclui-se que a metodologia apresentada, que utiliza softwares de domínio público, mostra vantagens na avaliação longitudinal de pacientes ortocirúrgicos, quando comparada aos métodos radiográficos convencionais, uma vez que as imagens geradas não apresentam magnificações ou sobreposições de estruturas e a maioria dos passos são automatizados, o que torna os procedimentos de mensuração mais precisos, além de disponibilizar uma maior quantidade de informações ao clínico ou pesquisador.INTRODUCTION: Limitations of 2D quantitative and qualitative evaluation of surgical displacements can be overcome by CBCT and three-dimensional imaging tools. OBJECTIVES: The method described in this study allows the assessment of changes in the condyles, rami, chin, maxilla and dentition by the comparison of CBCT scans before

  16. A statistical approach to motion compensated cone-beam

    Lyksborg, Mark; Hansen, Mads Fogtmann; Larsen, Rasmus

    One of the problems arising in radiotherapy planning is the quality of CT planning data. In the following attention is giving to the cone-beam scanning geometry where reconstruction of a 3D volume based on 2D projections, using the classic Feldkamp-Davis-Kress (FDK) algorithm requires a large...

  17. Increasing Cone-beam projection usage by temporal fitting

    Lyksborg, Mark; Hansen, Mads Fogtmann; Larsen, Rasmus

    2010-01-01

    A Cone-beam CT system can be used to image the lung region. The system records 2D projections which will allow 3D reconstruction however a reconstruction based on all projections will lead to a blurred reconstruction in regions were respiratory motion occur. To avoid this the projections are typi...

  18. A Statistical Approach to Motion Compensated Cone Beam Reconstruction

    Lyksborg, Mark; Hansen, Mads Fogtmann; Larsen, Rasmus

    2010-01-01

    One of the problems arising in radiotherapy planning is the quality of CT planning data. In the following attention is giving to the cone-beam scanning geometry where reconstruction of a 3D volume based on 2D projections, using the classic Feldkamp-Davis-Kress (FDK) algorithm requires a large...

  19. Cone-beam CT-guidance in Interventional Radiology

    Braak, S.J.

    2012-01-01

    OBJECTIVE. CBCT-guidance (CBCT-guidance) is a new stereotactic technique for needle interventions, combining 3D soft-tissue cone-beam CT, needle planningsoftware, and real-time fluoroscopy. Our objective was to evaluate the use, feasibility and outcome of this technique. To determine the effectiv

  20. 三维锥形束CT用于人牙咬痕认定的有效性比较研究%Effectiveness Assessment of 3-D Cone Beam CT Used in Human Bite Marks Identification

    吴砚; 陈新民; 沈韵; 余锦豪; 唐莹; 张以鸣; 朱磊; 徐远志

    2013-01-01

    The present study was aimed to use the 3-D cone beam CT (CBCT) as a new method in human bite marks identification which was carried out in experimental pigskin to assess its effectiveness in our laboratory. Bite marks were digital photographed according to American Board of Forensic Odontology (ABFO) guidelines. In this study, the data of the suspect's dental casts were collected by scanning in two ways: one was after plate scanning, in which the comparison overlays were generated by Adobe Photoshop8. 0 softwares the other was by CBCT, which generated comparison overlays automatically. The bite marks were blind identified with the two kinds of data of the suspect's dental casts respectively. ROC curve was used to analyze the sensitivity, specificity, and 95% confidence interval. The results showed that CBCT method got a larger area under the ROC curve: 0. 784 (SE=0. 074, 95% CI=0. 639-0. 929), and got a very high specificity (specificity 98. 7%, 95% CI=94. 5%-99. 8%). Thus, this study illustrates that the CBCT used in bite mark identification is an effective and accurate tool and has stronger ability to exclude suspects compared with the conventional method, but the comparison process needs further study to enhance its effectiveness in bite mark identification.%将三维锥形束CT(CBCT)用于人牙咬痕的认定,并通过猪皮载体上的实验咬痕开展其有效性分析.咬痕按照美国法医牙科协会(ABFO)指导原则进行数码拍照.嫌疑人牙模采用两种方法扫描采集数据:第一种是扫描仪扫描,再由常规方法Adobe Photoshop8.0软件生成比较overlay;第二种是使用CBCT三维扫描自动生成比较o-verlay.本研究将咬痕的数码相片分别与两种方法采集的牙模数据进行盲法比较认定,评定使用ROC曲线来分析灵敏度、特异度,并计算95%可信区间.结果显示CBCT法获得较大的ROC曲线下面积:0.784(SE=0.074,95%CI=0.639伍0.929);获得相当高的特异度(特异度98.7%,95

  1. A 3D printed beam splitter for polar neutral molecules

    Gordon, Sean D S

    2016-01-01

    We describe a beam splitter for polar neutral molecules. An electrostatic hexapole initially confines and guides a supersonic expansion of ammonia, and it then smoothly transforms into two bent quadrupole guides, thus splitting the molecular beam in two correlated fractions. This paves the way towards molecular beam experiments wherein one beam is modified through interactions with, e.g. a laser beam or another molecular beam, while the other one remains unmodified and serves as a reference. Because both beams originate from the same parent beam, such differential experiments can dramatically enhance the sensitivity. The highly complex electrode structure required for the beam splitter would be very difficult to build by traditional means. Instead, we introduce a new method of production: 3D printing of a plastic piece, followed by electroplating. The 3D printed piece can take any desired shape and, since the entire structure can be printed as a single piece, provides inherently precise alignment. Electroplat...

  2. Determination of HCME 3-D parameters using a full ice-cream cone model

    Na, Hyeonock; Moon, Yong-Jae; Lee, Harim

    2016-05-01

    It is very essential to determine three dimensional parameters (e.g., radial speed, angular width, source location) of Coronal Mass Ejections (CMEs) for space weather forecast. Several cone models (e.g., an elliptical cone model, an ice-cream cone model, an asymmetric cone model) have been examined to estimate these parameters. In this study, we investigate which cone type is close to a halo CME morphology using 26 CMEs: halo CMEs by one spacecraft (SOHO or STEREO-A or B) and as limb CMEs by the other ones. From cone shape parameters of these CMEs such as their front curvature, we find that near full ice-cream cone type CMEs are much closer to observations than shallow ice-cream cone type CMEs. Thus we develop a new cone model in which a full ice-cream cone consists of many flat cones with different heights and angular widths. This model is carried out by the following steps: (1) construct a cone for given height and angular width, (2) project the cone onto the sky plane, (3) select points comprising the outer boundary, and (4) minimize the difference between the estimated projection speeds with the observed ones. By applying this model to 12 SOHO/LASCO halo CMEs, we find that 3-D parameters from our method are similar to those from other stereoscopic methods (a geometrical triangulation method and a Graduated Cylindrical Shell model) based on multi-spacecraft data. We are developing a general ice-cream cone model whose front shape is a free parameter determined by observations.

  3. Application of cone beam computed tomography in facial imaging science

    Zacharias Fourie; Janalt Damstra; Yijin Ren

    2012-01-01

    The use of three-dimensional (3D) methods for facial imaging has increased significantly over the past years.Traditional 2D imaging has gradually being replaced by 3D images in different disciplines,particularly in the fields of orthodontics,maxillofacial surgery,plastic and reconstructive surgery,neurosurgery and forensic sciences.In most cases,3D facial imaging overcomes the limitations of traditional 2D methods and provides the clinician with more accurate information regarding the soft-tissues and the underlying skeleton.The aim of this study was to review the types of imaging methods used for facial imaging.It is important to realize the difference between the types of 3D imaging methods as application and indications thereof may differ.Since 3D cone beam computed tomography (CBCT) imaging will play an increasingly importanl role in orthodontics and orthognathic surgery,special emphasis should be placed on discussing CBCT applications in facial evaluations.

  4. Use of Cone Beam Computed Tomography in Endodontics

    Scarfe, William C.; Martin D. Levin; David Gane; Farman, Allan G.

    2009-01-01

    Cone Beam Computed Tomography (CBCT) is a diagnostic imaging modality that provides high-quality, accurate three-dimensional (3D) representations of the osseous elements of the maxillofacial skeleton. CBCT systems are available that provide small field of view images at low dose with sufficient spatial resolution for applications in endodontic diagnosis, treatment guidance, and posttreatment evaluation. This article provides a literature review and pictorial demonstration of CBCT as an imagin...

  5. Cone beam CT for dental and maxillofacial imaging: dose matters

    Pauwels, Ruben

    2015-01-01

    The widespread use of cone-beam CT (CBCT) in dentistry has led to increasing concern regarding justification and optimisation of CBCT exposures. When used as a substitute to multidetector CT (MDCT), CBCT can lead to significant dose reduction; however, low-dose protocols of current-generation MDCTs show that there is an overlap between CBCT and MDCT doses. More importantly, although the 3D information provided by CBCT can often lead to improved diagnosis and treatment compared with 2D radiogr...

  6. Three-dimensional ultrashort echo time cones T1ρ (3D UTE-cones-T1ρ ) imaging.

    Ma, Ya-Jun; Carl, Michael; Shao, Hongda; Tadros, Anthony S; Chang, Eric Y; Du, Jiang

    2017-03-20

    We report a novel three-dimensional (3D) ultrashort echo time (UTE) sequence employing Cones trajectory and T1ρ preparation (UTE-Cones-T1ρ ) for quantitative T1ρ assessment of short T2 tissues in the musculoskeletal system. A basic 3D UTE-Cones sequence was combined with a spin-locking preparation pulse for T1ρ contrast. A relatively short TR was used to decrease the scan time, which required T1 measurement and compensation using 3D UTE-Cones data acquisitions with variable TRs. Another strategy to reduce the total scan time was to acquire multiple Cones spokes (Nsp ) after each T1ρ preparation and fat saturation. Four spin-locking times (TSL = 0-20 ms) were acquired over 12 min, plus another 7 min for T1 measurement. The 3D UTE-Cones-T1ρ sequence was compared with a two-dimensional (2D) spiral-T1ρ sequence for the imaging of a spherical CuSO4 phantom and ex vivo meniscus and tendon specimens, as well as the knee and ankle joints of healthy volunteers, using a clinical 3-T scanner. The CuSO4 phantom showed a T1ρ value of 76.5 ± 1.6 ms with the 2D spiral-T1ρ sequence, as well as 85.7 ± 3.6 and 89.2 ± 1.4 ms for the 3D UTE-Cones-T1ρ sequences with Nsp of 1 and 5, respectively. The 3D UTE-Cones-T1ρ sequence provided shorter T1ρ values for the bovine meniscus sample relative to the 2D spiral-T1ρ sequence (10-12 ms versus 16 ms, respectively). The cadaveric human Achilles tendon sample could only be imaged with the 3D UTE-Cones-T1ρ sequence (T1ρ  = 4.0 ± 0.9 ms), with the 2D spiral-T1ρ sequence demonstrating near-zero signal intensity. Human studies yielded T1ρ values of 36.1 ± 2.9, 18.3 ± 3.9 and 3.1 ± 0.4 ms for articular cartilage, meniscus and the Achilles tendon, respectively. The 3D UTE-Cones-T1ρ sequence allows volumetric T1ρ measurement of short T2 tissues in vivo.

  7. WE-G-207-03: Mask Guided Image Reconstruction (MGIR): A Novel Method for Ultra-Low-Dose 3D and Enhanced 4D Cone-Beam Computer-Tomography

    Park, C; Zhang, H; Chen, Y; Fan, Q; Kahler, D; Li, J; Liu, C; Lu, B [Univ Florida, Gainesville, FL (United States)

    2015-06-15

    Purpose: Recently, compressed sensing (CS) based iterative reconstruction (IR) method is receiving attentions to reconstruct high quality cone beam computed tomography (CBCT) images using sparsely sampled or noisy projections. The aim of this study is to develop a novel baseline algorithm called Mask Guided Image Reconstruction (MGIR), which can provide superior image quality for both low-dose 3DCBCT and 4DCBCT under single mathematical framework. Methods: In MGIR, the unknown CBCT volume was mathematically modeled as a combination of two regions where anatomical structures are 1) within the priori-defined mask and 2) outside the mask. Then we update each part of images alternatively thorough solving minimization problems based on CS type IR. For low-dose 3DCBCT, the former region is defined as the anatomically complex region where it is focused to preserve edge information while latter region is defined as contrast uniform, and hence aggressively updated to remove noise/artifact. In 4DCBCT, the regions are separated as the common static part and moving part. Then, static volume and moving volumes were updated with global and phase sorted projection respectively, to optimize the image quality of both moving and static part simultaneously. Results: Examination of MGIR algorithm showed that high quality of both low-dose 3DCBCT and 4DCBCT images can be reconstructed without compromising the image resolution and imaging dose or scanning time respectively. For low-dose 3DCBCT, a clinical viable and high resolution head-and-neck image can be obtained while cutting the dose by 83%. In 4DCBCT, excellent quality 4DCBCT images could be reconstructed while requiring no more projection data and imaging dose than a typical clinical 3DCBCT scan. Conclusion: The results shown that the image quality of MGIR was superior compared to other published CS based IR algorithms for both 4DCBCT and low-dose 3DCBCT. This makes our MGIR algorithm potentially useful in various on

  8. 3D shaping of electron beams using amplitude masks

    Shiloh, Roy

    2016-01-01

    Shaping the electron wavefunction in three dimensions may prove to be an indispensable tool for research involving atomic-sized particle trapping, manipulation, and synthesis. We utilize computer-generated holograms to sculpt electron wavefunctions in a standard transmission electron microscope in 3D, and demonstrate the formation of electron beams exhibiting high intensity along specific trajectories as well as shaping the beam into a 3D lattice of hot-spots. The concepts presented here are similar to those used in light optics for trapping and tweezing of particles, but at atomic scale resolutions.

  9. Development of 3D beam-beam simulation for the Tevatron

    Stern, E.; Amundson, J.; Spentzouris, P.; Valishev, A.; /Fermilab; Qiang, J.; Ryne, R.; /LBL, Berkeley

    2007-06-01

    We present status of development of a 3D Beam-Beam simulation code for simulating the Fermilab Tevatron collider. The essential features of the code are 3D particle-in-cell Poisson solver for calculating the Beam-Beam electromagnetic interactions with additional modules for linear optics, machine impedance and chromaticity, and multiple bunch tracking. The simulations match synchrobetatron oscillations measured at the VEPP-2M collider. The impedance calculations show beam instability development consistent with analytic expressions.

  10. Experimental demonstration of 3D accelerating beam arrays.

    Yu, Xianghua; Li, Runze; Yan, Shaohui; Yao, Baoli; Gao, Peng; Han, Guoxia; Lei, Ming

    2016-04-10

    Accelerating beams have attracted much attention in the frontiers of optical physics and technology owing to their unique propagation dynamics of nondiffracting, self-healing, and freely accelerating along curved trajectories. Such behaviors essentially arise from the particular phase factor occurring in their spatial frequency spectrum, e.g., the cubic phase associated to the spectrum of Airy beam. In this paper, we theoretically and experimentally demonstrate a sort of accelerating beam arrays, which are composed of spatially separated accelerating beams. By superimposing kinoforms of multifocal patterns into the spatial frequency spectrum of accelerating beams, different types of beam arrays, e.g., Airy beam arrays and two-main-lobe accelerating beam arrays, are generated and measured by scanning a reflection mirror near the focal region along the optical axis. The 3D intensity patterns reconstructed from the experimental data present good agreement with the theoretical counterparts. The combination of accelerating beams with optical beam arrays proposed here may find potential applications in various fields such as optical microscopes, optical micromachining, optical trapping, and so on.

  11. Cone beam computed tomography in veterinary dentistry

    van Thielen, B.; Siguenza, F.; Hassan, B.

    2012-01-01

    The purpose of this study was to assess the feasibility of cone beam computed tomography (CBCT) in imaging dogs and cats for diagnostic dental veterinary applications. CBCT scans of heads of six dogs and two cats were made. Dental panoramic and multi-planar reformatted (MPR) para-sagittal reconstruc

  12. Cone beam CT, wat moet ik ermee?

    R. Hoogeveen

    2013-01-01

    De cone beam-ct-scan (cbct-scan) maakt een opmars in de tandheelkunde vanwege de toegevoegde waarde van de derde dimensie in de diagnostiek. Deze extra informatie wordt verkregen ten koste van een hogere stralenbelasting en een daarmee gepaard gaand hoger risico voor de patiënt. Om de clinicus te he

  13. Beam and Truss Finite Element Verification for DYNA3D

    Rathbun, H J

    2007-07-16

    The explicit finite element (FE) software program DYNA3D has been developed at Lawrence Livermore National Laboratory (LLNL) to simulate the dynamic behavior of structures, systems, and components. This report focuses on verification of beam and truss element formulations in DYNA3D. An efficient protocol has been developed to verify the accuracy of these structural elements by generating a set of representative problems for which closed-form quasi-static steady-state analytical reference solutions exist. To provide as complete coverage as practically achievable, problem sets are developed for each beam and truss element formulation (and their variants) in all modes of loading and physical orientation. Analyses with loading in the elastic and elastic-plastic regimes are performed. For elastic loading, the FE results are within 1% of the reference solutions for all cases. For beam element bending and torsion loading in the plastic regime, the response is heavily dependent on the numerical integration rule chosen, with higher refinement yielding greater accuracy (agreement to within 1%). Axial loading in the plastic regime produces accurate results (agreement to within 0.01%) for all integration rules and element formulations. Truss elements are also verified to provide accurate results (within 0.01%) for elastic and elastic-plastic loading. A sample problem to verify beam element response in ParaDyn, the parallel version DYNA3D, is also presented.

  14. 3D silicon pixel sensors: Recent test beam results

    Hansson, P; Sandaker, H; Korolkov, I; Barrera, C; Wermes, N; Borri, M; Grinstein, S; Troyano, I; Grenier, P; Devetak, E; Fleta, C; Kenney, C; Tsybychev, D; Nellist, C; Chmeissan, M; Su, D; DeWilde, B; Silverstein, D; Dorholt, O; Tsung, J; Sjoebaek, K; Stupak, J; Slaviec, T; Micelli, A; Helle, K; Bolle, E; Huegging, F; Kocian, M; Fazio, S; Balbuena, J; Dalla Betta, G F; La Rosa, A; Rivero, F; Mastroberardino, A; Hasi, J; Darbo, G; Boscardin, M; Da Via, C; Nordahl, P; Giordani, M; Jackson, P; Rohne, O; Gemme, C; Young, C

    2011-01-01

    The 3D silicon sensors aimed for the ATLAS pixel detector upgrade have been tested with a high energy pion beam at the CERN SPS in 2009. Two types of sensor layouts were tested: full-3D assemblies fabricated in Stanford, where the electrodes penetrate the entire silicon wafer thickness, and modified-3D assemblies fabricated at FBK-irst with partially overlapping electrodes. In both cases three read-out electrodes are ganged together to form pixels of dimension 50 x 400 mu m(2). Data on the pulse height distribution, tracking efficiency and resolution were collected for various particle incident angles, with and without a 1.6 T magnetic field. Data from a planar sensor of the type presently used in the ATLAS detector were used at the same time to give comparison. Published by Elsevier B.V.

  15. 3D silicon pixel sensors: Recent test beam results

    Hansson, P., E-mail: phansson@cern.c [University of Oslo (Norway); Balbuena, J.; Barrera, C. [CNM Barcelona (Spain); Bolle, E. [University of Oslo (Norway); Borri, M. [Torino University (Italy); Boscardin, M. [FBK Trento (Italy); Chmeissan, M. [IFAE Barcelona (Spain); Dalla Betta, G.-F. [Universita di Trento and INFN Trento (Italy); Darbo, G. [INFN Genova (Italy); Da Via, C. [University of Manchester (United Kingdom); Devetak, E.; DeWilde, B. [Stony Brook University (United States); Su, D. [SLAC (United States); Dorholt, O. [University of Oslo (Norway); Fazio, S. [Calabria University (Italy); Fleta, C. [CNM Barcelona (Spain); Gemme, C. [INFN Genova (Italy); Giordani, M. [University of Udine and INFN Udine (Italy); Gjersdal, H. [University of Oslo (Norway); Grenier, P. [SLAC (United States)

    2011-02-01

    The 3D silicon sensors aimed for the ATLAS pixel detector upgrade have been tested with a high energy pion beam at the CERN SPS in 2009. Two types of sensor layouts were tested: full-3D assemblies fabricated in Stanford, where the electrodes penetrate the entire silicon wafer thickness, and modified-3D assemblies fabricated at FBK-irst with partially overlapping electrodes. In both cases three read-out electrodes are ganged together to form pixels of dimension 50x400{mu}m{sup 2}. Data on the pulse height distribution, tracking efficiency and resolution were collected for various particle incident angles, with and without a 1.6 T magnetic field. Data from a planar sensor of the type presently used in the ATLAS detector were used at the same time to give comparison.

  16. Cone-beam computed tomography: A miracle for orthodontics!

    Jeevan M Khatri

    2015-01-01

    Full Text Available The branch of oral medicine and radiology has always played a role of back stage worker for the branch of orthodontics and dentofacial orthopaedics. It would have been difficult for an orthodontist to gift the bright smiles to his/her patients without the 2D and 3D black and white pictures provided by the oral radiologist. Moreover, the series of advances in the various imaging modalities are playing the role of a magician for the branch of orthodontia. The present article provides valuable information about one such miracle for the field of orthodontics-cone beam computed tomography (CBCT.

  17. Accuracy of implant placement based on pre-surgical planning of three-dimensional cone-beam images: a pilot study.

    Assche, N. Van; Steenberghe, D van; Guerrero, M.E.; Hirsch, E.; Schutyser, F.A.C.; Quirynen, M.; Jacobs, R.

    2007-01-01

    AIM: To evaluate the precision of transfer of a computer-based three-dimensional (3D) planning, using re-formatted cone-beam images, for oral implant placement in partially edentulous jaws. MATERIAL AND METHODS: Four formalin-fixed cadaver jaws were imaged in a 3D Accuitomo FPD cone-beam computed to

  18. Cone Beam Computed Tomography - Know its Secrets

    Kumar, Mohan; Shanavas, Muhammad; Sidappa, Ashwin; Kiran, Madhu

    2015-01-01

    Cone-beam computed tomography (CBCT) is an advanced imaging modality that has high clinical applications in the field of dentistry. CBCT proved to be a successful investigative modality that has been used for dental and maxillofacial imaging. Radiation exposure dose from CBCT is 10 times less than from conventional CT scans during maxillofacial exposure. Furthermore, CBCT is highly accurate and can provide a three-dimensional volumetric data in axial, sagittal and coronal planes. This article...

  19. Hollow Cone Electron Imaging for Single Particle 3D Reconstruction of Proteins

    Tsai, Chun-Ying; Chang, Yuan-Chih; Lobato, Ivan; van Dyck, Dirk; Chen, Fu-Rong

    2016-06-01

    The main bottlenecks for high-resolution biological imaging in electron microscopy are radiation sensitivity and low contrast. The phase contrast at low spatial frequencies can be enhanced by using a large defocus but this strongly reduces the resolution. Recently, phase plates have been developed to enhance the contrast at small defocus but electrical charging remains a problem. Single particle cryo-electron microscopy is mostly used to minimize the radiation damage and to enhance the resolution of the 3D reconstructions but it requires averaging images of a massive number of individual particles. Here we present a new route to achieve the same goals by hollow cone dark field imaging using thermal diffuse scattered electrons giving about a 4 times contrast increase as compared to bright field imaging. We demonstrate the 3D reconstruction of a stained GroEL particle can yield about 13.5 Å resolution but using a strongly reduced number of images.

  20. 3D sound in the telepresence project BEAMING

    Olesen, Søren Krarup; Markovic, Milos; Madsen, Esben;

    2012-01-01

    for the Visitor, 3D audio is provided through headphones. It is rendered based on the Locals' coordinates via a common Internet database including local positional tracking to ensure that information on the Visitor's head rotation has a minimum delay through the network. The BEAMING project currently addresses...... three applications: A general purpose theatrical scene, a teaching situation and a medical patient-visiting-doctor scenario. The March 2012 project review deals with the teaching situation. This involves a single microphone recording followed by signal processing that reconstructs the spatial content...

  1. 锥形束 CT 融合三维面像评估正颌术后软硬组织的变化%Feasibility of integrating 3D photos and cone-beam computed tomography images used to evaluate changes of soft and hard tissue after orthognathic surgery

    王哲; 朱榴宁; 周琳; 伊彪

    2016-01-01

    目的:探讨锥形束 CT(cone-beam computed tomography,CBCT)融合三维面像用于研究牙颌面畸形患者正颌术后软硬组织变化的可行性,并应用此方法初步测量各软硬组织标志点手术前后的位置变化。方法:选取10例牙颌面畸形患者,分别于术前(T0)和术后3个月(T1)拍摄大视野 CBCT 和三维面像。利用 MIMICS 和 Geomagic Studio 软件对图像进行处理分析,将 CBCT 进行阈值分割并与三维面像融合,生成新的三维立体模型,探讨该方法可行性。使用3D 色谱分析(3D color map)和测量平均距离对 CBCT 与三维面像配准过程的误差进行定性和定量分析。通过 CBCT 骨组织配准,将新生成的手术前后三维模型置于同一空间坐标系,测量各标志点[鼻尖点(prona-sale,Prn )、鼻下点(subnasale,Sn)、上唇突点(labrale superior,Ls)、前鼻棘点(anterior nasal spine,ANS)、上齿槽座点(subspinale,A)、上中切牙点(upper incisor edge,UIE)]手术前后位置变化。结果:CBCT 融合三维面像用于研究正颌术后软硬组织变化具有可行性,配准误差在0.3 mm 以内,通过3D 色谱分析直观看到,面部区域配准良好。正颌术后唇部各标志点(Ls、ANS、A、UIE)位置差异有统计学意义(P <0.05),而鼻部标志点(Prn、Sn)位置差异无统计学意义(P >0.1)。结论:CBCT 融合三维面像作为一种新方法可以用于临床研究正颌术后软硬组织变化,具有较高的精确度和可重复性。正颌术后唇部软硬组织标志点位置明显变化,而鼻部标志点位置受正颌手术影响较小。%Objective:To evaluate the feasibility of integrating 3D photos and cone-beam computed tomography (CBCT)images and to assess the degree of error that may occur during the above process,and to analyze soft and hard tissue changes after orthognathic surgery using this new method

  2. Cone Beam Computed Tomography Evaluation of Inverted Mesiodentes.

    Al-Sehaibany, Fares S; Marzouk, Hazem M; Salama, Fouad S

    2016-01-01

    A mesiodens is the most common type of supernumerary teeth. The purpose of this report is to present a rare occurrence of non-syndromic impacted inverted mesiodentes in an 8.5-year-old boy who presented with a chief complaint of delayed eruption of his permanent maxillary left central incisor. Occlusal and panoramic radiographs, as well as cone beam computed tomography (CBCT) with a three-dimensional (3-D) reconstruction image, confirmed that one supernumerary tooth had perforated the nasal fossa floor and the other was in close approximation to the to the same site. Surgical removal of both mesiodentes was indicated. Radiographic evidence of complete healing was observed 12 months following surgical removal. The use of CBCT with a 3-D reconstruction image as a tool in diagnosis and evaluation of healing after surgical removal is recommended.

  3. Calibration of Cone Beam Rotational X-Ray Image Sequence

    YUHengyong; MOUXuanqin; CAIYuanlong

    2004-01-01

    The real X-ray projection does not abide by Lambert-Beer Law, since the X-ray is polychromatic and the imaging chains are nonlinear. Based on the generating process of X-ray images, an equivalent nonlinear transform model is firstly proposed which considers all the nonlinear factors as one nonlinear transform. Then the 3D (three-dimensional) X-ray projection of cone beam is defined. The constraints of Radon transform, named H-L (Helgasson-ludwig) consistency conditions, are expanded to fan-beam. After that an algorithm is developed to calibrate Rotational X-ray image sequence (RXIS). The algorithm uses a set of exponential functions to approximate the nonlinear inverse transform. According to expanded H-L consistency conditions, finally a kind of nonlinear measure for RXIS is defined. Experimental results show that the proposed algorithm can decrease the nonlinear measure to below 0.01.

  4. Accuracy assessment of three-dimensional surface reconstructions of teeth from cone beam computed tomography scans

    Al-Rawi, B.; Hassan, B.; Vandenberge, B.; Jacobs, R.

    2010-01-01

    The use of three-dimensional (3D) models of the dentition obtained from cone beam computed tomography (CBCT) is becoming increasingly more popular in dentistry. A recent trend is to replace the traditional dental casts with digital CBCT models for diagnosis, treatment planning and simulation. The ac

  5. Precision of identifying cephalometric landmarks with cone beam computed tomography in vivo

    Hassan, B.; Nijkamp, P.; Verheij, H.; Tairie, J.; Vink, C.; van der Stelt, P.; van Beek, H.

    2013-01-01

    The study aims were to assess the precision and time required to conduct cephalometric analysis with cone-beam computed tomography (CBCT) in vivo on both three-dimensional (3D) surface models and multi-planar reformations (MPR) images. Datasets from 10 patients scanned with CBCT were used to create

  6. Full data consistency conditions for cone-beam projections with sources on a plane.

    Clackdoyle, Rolf; Desbat, Laurent

    2013-12-07

    Cone-beam consistency conditions (also known as range conditions) are mathematical relationships between different cone-beam projections, and they therefore describe the redundancy or overlap of information between projections. These redundancies have often been exploited for applications in image reconstruction. In this work we describe new consistency conditions for cone-beam projections whose source positions lie on a plane. A further restriction is that the target object must not intersect this plane. The conditions require that moments of the cone-beam projections be polynomial functions of the source positions, with some additional constraints on the coefficients of the polynomials. A precise description of the consistency conditions is that the four parameters of the cone-beam projections (two for the detector, two for the source position) can be expressed with just three variables, using a certain formulation involving homogeneous polynomials. The main contribution of this work is our demonstration that these conditions are not only necessary, but also sufficient. Thus the consistency conditions completely characterize all redundancies, so no other independent conditions are possible and in this sense the conditions are full. The idea of the proof is to use the known consistency conditions for 3D parallel projections, and to then apply a 1996 theorem of Edholm and Danielsson that links parallel to cone-beam projections. The consistency conditions are illustrated with a simulation example.

  7. Auto calibration of a cone-beam-CT

    Gross, Daniel; Heil, Ulrich; Schulze, Ralf; Schoemer, Elmar; Schwanecke, Ulrich [Department of Design, Computer Science and Media, RheinMain University of Applied Sciences, 65195 Wiesbaden, Germany and Institute of Computer Science, Johannes Gutenberg University Mainz, 55128 Mainz (Germany); Department of Oral Surgery (and Oral Radiology), University Medical Center of the Johannes Gutenberg University Mainz, 55131 Mainz (Germany); Institute of Computer Science, Johannes Gutenberg University Mainz, 55128 Mainz (Germany); Department of Design, Computer Science and Media, RheinMain University of Applied Sciences, 65195 Wiesbaden (Germany)

    2012-10-15

    Purpose: This paper introduces a novel autocalibration method for cone-beam-CTs (CBCT) or flat-panel CTs, assuming a perfect rotation. The method is based on ellipse-fitting. Autocalibration refers to accurate recovery of the geometric alignment of a CBCT device from projection images alone, without any manual measurements. Methods: The authors use test objects containing small arbitrarily positioned radio-opaque markers. No information regarding the relative positions of the markers is used. In practice, the authors use three to eight metal ball bearings (diameter of 1 mm), e.g., positioned roughly in a vertical line such that their projection image curves on the detector preferably form large ellipses over the circular orbit. From this ellipse-to-curve mapping and also from its inversion the authors derive an explicit formula. Nonlinear optimization based on this mapping enables them to determine the six relevant parameters of the system up to the device rotation angle, which is sufficient to define the geometry of a CBCT-machine assuming a perfect rotational movement. These parameters also include out-of-plane rotations. The authors evaluate their method by simulation based on data used in two similar approaches [L. Smekal, M. Kachelriess, S. E, and K. Wa, 'Geometric misalignment and calibration in cone-beam tomography,' Med. Phys. 31(12), 3242-3266 (2004); K. Yang, A. L. C. Kwan, D. F. Miller, and J. M. Boone, 'A geometric calibration method for cone beam CT systems,' Med. Phys. 33(6), 1695-1706 (2006)]. This allows a direct comparison of accuracy. Furthermore, the authors present real-world 3D reconstructions of a dry human spine segment and an electronic device. The reconstructions were computed from projections taken with a commercial dental CBCT device having two different focus-to-detector distances that were both calibrated with their method. The authors compare their reconstruction with a reconstruction computed by the manufacturer of

  8. High aspect ratio 3D nanopatterning using Proton Beam Writing

    van Kan, Jeroen A.

    2009-03-01

    Proton beam writing (PBW) is a new direct write lithography using MeV protons, and is unique because of its ability to fabricate 3D structures of high aspect ratio structures directly in resist material like PMMA, SU-8 and HSQ. The introduction by CIBA, Singapore of a dedicated PBW facility, capable of writing at the micro- and nano- scale has facilitated high aspect ratio nanostructuring. PBW has demontrated high aspect ratio walls in HSQ down to the 20nm level. In recent experiments details down to sub 20 nm have been achieved in PMMA. Monte-Carlo calculations have shown that structuring down to the nanometer level is feasible. All this is possible because of the virtual absence of proximity effects (unwanted resist exposure by stray secondary electrons). The design and performance of this unique nanoprobe facility will be discussed. Two potential fields of application (eg nanofluidics and nanowire integration) of PBW will be discussed. Currently nanofluidics devices have typically only one critical dimension below 100 nm. Here we will introduce PBW as a powerful technique to fabricate molds for replication of PDMS nanofluidic circuits down to the sub 100 nm level in two dimensions. Initial chips with dimension down to 150 nm have successfully been used to study DNA folding in quasi-1d nanochannels in tandem with fluorescence imaging. Since the size of these PDMS nanochannels is not limited by the PDMS or PBW further miniaturization down to the sub 100 nm level is a realistic goal and initial results will be discussed. Nanowires are a potential building block for nano-electronic devices, and one critical problem is the integration of nanowires to form contacts. Porous alumina templates and high energy ion-tracks have been used for the production of nanowire templates in a random orientation. Since PBW is the only true 3D direct write nanolithographic technique it can be used to fabricate nanowire templates in a controlled manner.

  9. Cone beam computed tomography in endodontics.

    Durack, Conor; Patel, Shanon

    2012-01-01

    Cone beam computed tomography (CBCT) is a contemporary, radiological imaging system designed specifically for use on the maxillo-facial skeleton. The system overcomes many of the limitations of conventional radiography by producing undistorted, three-dimensional images of the area under examination. These properties make this form of imaging particularly suitable for use in endodontics. The clinician can obtain an enhanced appreciation of the anatomy being assessed, leading to an improvement in the detection of endodontic disease and resulting in more effective treatment planning. In addition, CBCT operates with a significantly lower effective radiation dose when compared with conventional computed tomography (CT). The purpose of this paper is to review the current literature relating to the limitations and potential applications of CBCT in endodontic practice.

  10. Cone beam computed tomography in endodontic

    Durack, Conor; Patel, Shanon, E-mail: conordurack1@hotmail.com [Unit of Endodontology, Department of Conservative Dentistry, King' s College London, London (United Kingdom)

    2012-07-01

    Cone beam computed tomography (CBCT) is a contemporary, radiological imaging system designed specifically for use on the maxillofacial skeleton. The system overcomes many of the limitations of conventional radiography by producing undistorted, three-dimensional images of the area under examination. These properties make this form of imaging particularly suitable for use in endodontic. The clinician can obtain an enhanced appreciation of the anatomy being assessed, leading to an improvement in the detection of endodontic disease and resulting in more effective treatment planning. In addition, CBCT operates with a significantly lower effective radiation dose when compared with conventional computed tomography (CT). The purpose of this paper is to review the current literature relating to the limitations and potential applications of CBCT in endodontic practice. (author)

  11. 基于3D-CT、4D-CT和锥形束CT定义的非小细胞肺癌内靶区比较%Comparison of internal target volumes defined on three-dimensional CT, four-dimensional CT and cone-beam CT images of non-small-cell lung cancer

    李奉祥; 李建彬; 马志芳; 张英杰; 邢军; 戚焕鹏; 尚东平; 余宁莎

    2014-01-01

    Objective To compare positional and volumetric differences between internal target volumes defined on three-dimensional CT (3D-CT),four-dimensional CT (4D-CT) and cone-beam CT (CBCT) images of non-small-cell lung cancer.Methods Thirty-one patients with NSCLC sequentially underwent 3D-CT and 4D-CT simulation scans of the thorax during free breathing.A 3D conformal treatment plan was created based on 3D-CT.The CBCT images were obtained in the first fraction and registered to the planning CT using the bony anatomy registration.All target volumes were contoured with the same protocol by a radiation oncologist.GTVs were contoured based on 3D-CT,maximum intensity projection (MIP) of 4D-CT and CBCT.CTV3D,ITVMIPand ITVCBCTWere defined with a margin of 7 mm accounting for microscopic disease.ITV10mm and ITV5 mm were defined based on CTV3D.ITV10 mm with a margin of 5 mm in LR,AP directions and 10 mm in CC direction,while ITV5 mm with an isotropic internal margin (IM) of 5 mm.The differences in the position,size,Dice's similarity coefficient (DSC) and inclusion relation of different volumes were compared.Results The median size ratio of ITV10 mm,ITV5mm,ITVMIPto ITVCBCTwere 2.33,1.88,1.03 respectively for tumors in the upper lobe and 2.13,1.76,1.10 respectively for tumors in the middle-lower lobe.The median DSC of ITVMIP and ITVCBCT(0.83) was greater than that of ITV10 mm and ITVcBcT (0.6) and ITV5 mm and ITVCBCT (0.66) for all patients (Z =-4.86,-4.86,P < 0.05).The median percentages of ITVCBCT not included in ITV10 mm,ITV5 mm,ITVMIPwere 0.10%,1.63% and 15.21% respectively,while the median percentage of ITV10mm,ITV5mm,ITVMIP,not included in ITVCBCT were 57.08%,48.89% and 20.04%,respectively.The median percentage of ITVCBCT not included in ITV5 mm was 1.24% for tumors in the upper lobe and 5.8% for tumors in the middle-lower lobe.Conclusions The individual ITV based on 4D-CT can't encompass the ITV based on CBCT effectively.The use of the ITV derived from 4

  12. Dynamic cone beam CT angiography of carotid and cerebral arteries using canine model

    Cai Weixing; Zhao Binghui; Conover, David; Liu Jiangkun; Ning Ruola [Department of Imaging Sciences, University of Rochester, 601 Elmwood Avenue, Rochester, New York 14642 (United States); Department of Radiology, Shanghai 6th People' s Hospital, 600 Yishan Road, Xuhui, Shanghai (China); Koning Corporation, Lennox Tech Enterprise Center, 150 Lucius Gordon Drive Suite 112, West Henrietta, New York 14586 (United States); Department of Imaging Sciences, University of Rochester, 601 Elmwood Avenue, Rochester, New York 14642 (United States); Department of Imaging Sciences, University of Rochester, 601 Elmwood Avenue, Rochester, New York 14642 (United States) and Koning Corporation, Lennox Tech Enterprise Center, 150 Lucius Gordon Drive Suite 112, West Henrietta, New York 14586 (United States)

    2012-01-15

    Purpose: This research is designed to develop and evaluate a flat-panel detector-based dynamic cone beam CT system for dynamic angiography imaging, which is able to provide both dynamic functional information and dynamic anatomic information from one multirevolution cone beam CT scan. Methods: A dynamic cone beam CT scan acquired projections over four revolutions within a time window of 40 s after contrast agent injection through a femoral vein to cover the entire wash-in and wash-out phases. A dynamic cone beam CT reconstruction algorithm was utilized and a novel recovery method was developed to correct the time-enhancement curve of contrast flow. From the same data set, both projection-based subtraction and reconstruction-based subtraction approaches were utilized and compared to remove the background tissues and visualize the 3D vascular structure to provide the dynamic anatomic information. Results: Through computer simulations, the new recovery algorithm for dynamic time-enhancement curves was optimized and showed excellent accuracy to recover the actual contrast flow. Canine model experiments also indicated that the recovered time-enhancement curves from dynamic cone beam CT imaging agreed well with that of an IV-digital subtraction angiography (DSA) study. The dynamic vascular structures reconstructed using both projection-based subtraction and reconstruction-based subtraction were almost identical as the differences between them were comparable to the background noise level. At the enhancement peak, all the major carotid and cerebral arteries and the Circle of Willis could be clearly observed. Conclusions: The proposed dynamic cone beam CT approach can accurately recover the actual contrast flow, and dynamic anatomic imaging can be obtained with high isotropic 3D resolution. This approach is promising for diagnosis and treatment planning of vascular diseases and strokes.

  13. Accuracy of Cone Beam Computed Tomography in Diagnosis and Treatment Planning of Periodontal Bone Defects: A Case Report

    Songa, Vajra Madhuri; Jampani, Narendra Dev; Babu, Venkateshwara; Buggapati, Lahari; Mittapally, Sowjanya

    2014-01-01

    Diagnosis of periodontitis depend mostly on traditional two-dimensional (2-D) radiographic assessment. Regardless of efforts in improving reliability, present methods of detecting bone level changes over time or determining three-dimensional (3-D) architecture of osseous defects are lacking. To improve the diagnostic potential, an imaging modality which would give an undistorted 3-D vision of a tooth and surrounding structures is imperative. Cone beam computed tomography (CBCT) generates 3D v...

  14. Pulsar average waveforms and hollow cone beam models

    Backer, D. C.

    1975-01-01

    An analysis of pulsar average waveforms at radio frequencies from 40 MHz to 15 GHz is presented. The analysis is based on the hypothesis that the observer sees one cut of a hollow-cone beam pattern and that stationary properties of the emission vary over the cone. The distributions of apparent cone widths for different observed forms of the average pulse profiles (single, double/unresolved, double/resolved, triple and multiple) are in modest agreement with a model of a circular hollow-cone beam with random observer-spin axis orientation, a random cone axis-spin axis alignment, and a small range of physical hollow-cone parameters for all objects.

  15. Use of cone beam computed tomography in periodontology.

    Acar, Buket; Kamburoğlu, Kıvanç

    2014-05-28

    Diagnosis of periodontal disease mainly depends on clinical signs and symptoms. However, in the case of bone destruction, radiographs are valuable diagnostic tools as an adjunct to the clinical examination. Two dimensional periapical and panoramic radiographs are routinely used for diagnosing periodontal bone levels. In two dimensional imaging, evaluation of bone craters, lamina dura and periodontal bone level is limited by projection geometry and superpositions of adjacent anatomical structures. Those limitations of 2D radiographs can be eliminated by three-dimensional imaging techniques such as computed tomography. Cone beam computed tomography (CBCT) generates 3D volumetric images and is also commonly used in dentistry. All CBCT units provide axial, coronal and sagittal multi-planar reconstructed images without magnification. Also, panoramic images without distortion and magnification can be generated with curved planar reformation. CBCT displays 3D images that are necessary for the diagnosis of intra bony defects, furcation involvements and buccal/lingual bone destructions. CBCT applications provide obvious benefits in periodontics, however; it should be used only in correct indications considering the necessity and the potential hazards of the examination.

  16. Stray light in cone beam optical computed tomography: II. Reduction using a convergent light source

    Dekker, Kurtis H.; Battista, Jerry J.; Jordan, Kevin J.

    2016-04-01

    Optical cone beam computed tomography (CBCT) using a broad beam and CCD camera is a fast method for densitometry of 3D optical gel dosimeters. However, diffuse light sources introduce considerable stray light into the imaging system, leading to underestimation of attenuation coefficients and non-uniformities in CT images unless corrections are applied to each projection image. In this study, the light source of a commercial optical CT scanner is replaced with a convergent cone beam source consisting of almost exclusively image forming primary rays. The convergent source is achieved using a small isotropic source and a Fresnel lens. To characterize stray light effects, full-field cone beam CT imaging is compared to fan beam CT (FBCT) using a 1 cm high fan beam aperture centered on the optic axis of the system. Attenuating liquids are scanned within a large 96 mm diameter uniform phantom and in a small 13.5 mm diameter finger phantom. For the uniform phantom, cone and fan beam CT attenuation coefficients agree within a maximum deviation of (1  ±  2)% between mean values over a wide range from 0.036 to 0.43 cm-1. For the finger phantom, agreement is found with a maximum deviation of (4  ±  2)% between mean values over a range of 0.1-0.47 cm-1. With the convergent source, artifacts associated with refractive index mismatch and vessel optical features are more pronounced. Further optimization of the source size to achieve a balance between quantitative accuracy and artifact reduction should enable practical, accurate 3D dosimetry, avoiding time consuming 3D scatter measurements.

  17. Stray light in cone beam optical computed tomography: II. Reduction using a convergent light source.

    Dekker, Kurtis H; Battista, Jerry J; Jordan, Kevin J

    2016-04-07

    Optical cone beam computed tomography (CBCT) using a broad beam and CCD camera is a fast method for densitometry of 3D optical gel dosimeters. However, diffuse light sources introduce considerable stray light into the imaging system, leading to underestimation of attenuation coefficients and non-uniformities in CT images unless corrections are applied to each projection image. In this study, the light source of a commercial optical CT scanner is replaced with a convergent cone beam source consisting of almost exclusively image forming primary rays. The convergent source is achieved using a small isotropic source and a Fresnel lens. To characterize stray light effects, full-field cone beam CT imaging is compared to fan beam CT (FBCT) using a 1 cm high fan beam aperture centered on the optic axis of the system. Attenuating liquids are scanned within a large 96 mm diameter uniform phantom and in a small 13.5 mm diameter finger phantom. For the uniform phantom, cone and fan beam CT attenuation coefficients agree within a maximum deviation of (1  ±  2)% between mean values over a wide range from 0.036 to 0.43 cm(-1). For the finger phantom, agreement is found with a maximum deviation of (4  ±  2)% between mean values over a range of 0.1-0.47 cm(-1). With the convergent source, artifacts associated with refractive index mismatch and vessel optical features are more pronounced. Further optimization of the source size to achieve a balance between quantitative accuracy and artifact reduction should enable practical, accurate 3D dosimetry, avoiding time consuming 3D scatter measurements.

  18. Dynamic bowtie filter for cone-beam/multi-slice CT.

    Fenglin Liu

    Full Text Available A pre-patient attenuator ("bowtie filter" or "bowtie" is used to modulate an incoming x-ray beam as a function of the angle of the x-ray with respect to a patient to balance the photon flux on a detector array. While the current dynamic bowtie design is focused on fan-beam geometry, in this study we propose a methodology for dynamic bowtie design in multi-slice/cone-beam geometry. The proposed 3D dynamic bowtie is an extension of the 2D prior art. The 3D bowtie consists of a highly attenuating bowtie (HB filled in with heavy liquid and a weakly attenuating bowtie (WB immersed in the liquid of the HB. The HB targets a balanced flux distribution on a detector array when no object is in the field of view (FOV. The WB compensates for an object in the FOV, and hence is a scaled-down version of the object. The WB is rotated and translated in synchrony with the source rotation and patient translation so that the overall flux balance is maintained on the detector array. First, the mathematical models of different scanning modes are established for an elliptical water phantom. Then, a numerical simulation study is performed to compare the performance of the scanning modes in the cases of the water phantom and a patient cross-section without any bowtie and with a dynamic bowtie. The dynamic bowtie can equalize the numbers of detected photons in the case of the water phantom. In practical cases, the dynamic bowtie can effectively reduce the dynamic range of detected signals inside the FOV. Furthermore, the WB can be individualized using a 3D printing technique as the gold standard. We have extended the dynamic bowtie concept from 2D to 3D by using highly attenuating liquid and moving a scale-reduced negative copy of an object being scanned. Our methodology can be applied to reduce radiation dose and facilitate photon-counting detection.

  19. 胸段椎体转移癌放射治疗二维和三维位置验证的比较分析%Comparison of 2D kilovoltage-kilovoltage radiographs and 3D cone-beam computed tomography in position verification during thoracic spinal metastases cancer radiotherapy

    张爱华; 徐细明; 胡健; 戈伟; 徐利明; 邓君健

    2013-01-01

    目的 通过VARIAN-OBI系统提供二维KV-KV和三维锥形束CT(CBCT)位置验证模式,对比分析其在胸段椎体骨转移癌的应用,找寻其最佳图像引导放射治疗(IGRT)方式.方法 选择50例胸段椎体骨转移癌患者,其中男性33例,女性17例,中位年龄为57岁.随机分为A、B组,每次治疗前位置验证,A组行二维KV-KV位置验证,图像配准后记录位移偏差值,移动治疗床治疗,治疗结束后评估患者疼痛症状,按照世界卫生组织的疼痛评分标准评分;B组行三维CBCT位置验证,图像配准后,记录位移偏移值(包括旋转偏差),移动治疗床执行治疗,并记录患者疼痛指数.统计并计算均值和标准差,对比分析两种验证方式的差异.结果 A组和B组各获取125组图像,位移偏差:A组在Vertical(Vrt)、Longitudinal (Lng)、Lateral (Lat)的位移偏差分别为(0.02±0.14) cm、(0.02±0.13) cm、(-0.01±0.17)cm;B组为(0.04±0.15) cm、(0.01±0.14) cm、(-0.03±0.16)cm,两组数据比较,差异无统计学意义(P=0.642、0.549、0.996> 0.05);疼痛指数:A组患者为2.21±0.77,B组患者为3.03±0.80(P=0<0.05);验证用时:二维KV-KV配准时间为(3.97±0.63) min,三维CBCT配准时间为(8.13±0.98) min(P=0<0.05).结论 二维KV-KV与三维CBCT位置验证在位置移动偏差值的比较无统计学意义,均能满足临床应用需求.二维KV-KV位置验证相对三维CBCT位置验证,整个验证需要时间是后者的1/2~ 1/3,二维KV-KV位置验证是疼痛症状明显的椎体骨转移患者的首选方式.%Objective To analyze the difference between two-dimension(2D) kilovoltage-kilovoltage(KV-KV) and three-dimension (3D) cone -beam computed tomography (CBCT) verification in thoracic spinal metastases cancer radiotherapy, and find the best application of IGRT for thoracic metastases cancer patients by two radiotherapy position verification 2D KV-KV and 3D CBCT from Varian-OBI system. Methods A total of 50 thoracic metastases cancer

  20. Generalized Fourier slice theorem for cone-beam image reconstruction.

    Zhao, Shuang-Ren; Jiang, Dazong; Yang, Kevin; Yang, Kang

    2015-01-01

    The cone-beam reconstruction theory has been proposed by Kirillov in 1961, Tuy in 1983, Feldkamp in 1984, Smith in 1985, Pierre Grangeat in 1990. The Fourier slice theorem is proposed by Bracewell 1956, which leads to the Fourier image reconstruction method for parallel-beam geometry. The Fourier slice theorem is extended to fan-beam geometry by Zhao in 1993 and 1995. By combining the above mentioned cone-beam image reconstruction theory and the above mentioned Fourier slice theory of fan-beam geometry, the Fourier slice theorem in cone-beam geometry is proposed by Zhao 1995 in short conference publication. This article offers the details of the derivation and implementation of this Fourier slice theorem for cone-beam geometry. Especially the problem of the reconstruction from Fourier domain has been overcome, which is that the value of in the origin of Fourier space is 0/0. The 0/0 type of limit is proper handled. As examples, the implementation results for the single circle and two perpendicular circle source orbits are shown. In the cone-beam reconstruction if a interpolation process is considered, the number of the calculations for the generalized Fourier slice theorem algorithm is O(N^4), which is close to the filtered back-projection method, here N is the image size of 1-dimension. However the interpolation process can be avoid, in that case the number of the calculations is O(N5).

  1. Pulsar average wave forms and hollow-cone beam models

    Backer, D. C.

    1976-01-01

    Pulsar wave forms have been analyzed from observations conducted over a wide radio-frequency range to assess the wave-form morphologies and to measure wave-form widths. The results of the analysis compare favorably with the predictions of a model with a hollow-cone beam of fixed dimensions and with random orientation of both the observer and the cone axis with respect to the pulsar spin axis. A class of three-component wave forms is included in the model by adding a central pencil beam to the hollow-cone hypothesis. The consequences of a number of discrepancies between observations and quantitative predictions of the model are discussed.

  2. The current status of cone beam computed tomography imaging in orthodontics

    S. Kapila; Conley, R S; Harrell, W E

    2011-01-01

    Cone beam CT (CBCT) has become an increasingly important source of three dimensional (3D) volumetric data in clinical orthodontics since its introduction into dentistry in 1998. The purpose of this manuscript is to highlight the current understanding of, and evidence for, the clinical use of CBCT in orthodontics, and to review the findings to answer clinically relevant questions. Currently available information from studies using CBCT can be organized into five broad categories: 1, the assess...

  3. Comparative analysis between mandibular positions in centric relation and maximum intercuspation by cone beam computed tomography (CONE-BEAM)

    Ferreira,Amanda de Freitas; Henriques,João César Guimarães; Almeida,Guilherme de Araújo; Machado,Asbel Rodrigues; Machado, Naila Aparecida de Godoi; Fernandes Neto,Alfredo Júlio

    2009-01-01

    This research consisted of a quantitative assessment, and aimed to measure the possible discrepancies between the maxillomandibular positions for centric relation (CR) and maximum intercuspation (MI), using computed tomography volumetric cone beam (cone beam method). The sample of the study consisted of 10 asymptomatic young adult patients divided into two types of standard occlusion: normal occlusion and Angle Class I occlusion. In order to obtain the centric relation, a JIG device and mandi...

  4. Clinical applications of cone beam computed tomography in endodontics: A comprehensive review.

    Cohenca, Nestor; Shemesh, Hagay

    2015-06-01

    Cone beam computed tomography (CBCT) is a new technology that produces three-dimensional (3D) digital imaging at reduced cost and less radiation for the patient than traditional CT scans. It also delivers faster and easier image acquisition. By providing a 3D representation of the maxillofacial tissues in a cost- and dose-efficient manner, a better preoperative assessment can be obtained for diagnosis and treatment. This comprehensive review presents current applications of CBCT in endodontics. Specific case examples illustrate the difference in treatment planning with traditional periapical radiography versus CBCT technology.

  5. Projecting light beams with 3D waveguide arrays

    Crespi, Andrea; Bragheri, Francesca

    2017-01-01

    Free-space light beams with complex intensity patterns, or non-trivial phase structure, are demanded in diverse fields, ranging from classical and quantum optical communications, to manipulation and imaging of microparticles and cells. Static or dynamic spatial light modulators, acting on the phase or intensity of an incoming light wave, are the conventional choices to produce beams with such non-trivial characteristics. However, interfacing these devices with optical fibers or integrated optical circuits often requires difficult alignment or cumbersome optical setups. Here we explore theoretically and with numerical simulations the potentialities of directly using the output of engineered three-dimensional waveguide arrays, illuminated with linearly polarized light, to project light beams with peculiar structures. We investigate through a collection of illustrative configurations the far field distribution, showing the possibility to achieve orbital angular momentum, or to produce elaborate intensity or phase patterns with several singularity points. We also simulate the propagation of the projected beam, showing the possibility to concentrate light. We note that these devices should be at reach of current technology, thus perspectives are open for the generation of complex free-space optical beams from integrated waveguide circuits.

  6. Projecting light beams with 3D waveguide arrays

    Crespi, Andrea

    2016-01-01

    Free-space light beams with complex intensity patterns, or non-trivial phase structure, are demanded in diverse fields, ranging from classical and quantum optical communications, to manipulation and imaging of microparticles and cells. Static or dynamic spatial light modulators, acting on phase or intensity of an incoming light wave, are the conventional choices to produce beams with such non-trivial characteristics. However, interfacing these devices with optical fibers or integrated optical circuits often requires difficult alignment or cumbersome optical setups. Here we explore theoretically and with numerical simulations the potentialities of directly using the output of engineered three-dimensional waveguide arrays, illuminated with linearly polarized light, to project light beams with peculiar structures. We investigate through a collection of illustrative configurations the far field distribution, showing the possibility to achieve orbital angular momentum, or to produce elaborate intensity or phase pa...

  7. Beam section stiffness properties usig 3D finite elements

    Couturier, Philippe; Krenk, Steen; Høgsberg, Jan Becker

    2013-01-01

    The cross-section properties of a beam is characterized by a six by six stiffness matrix, relating the six generalized strains to the conjugate section forces. The problem is formulated as a single-layer finite element model of a slice of the beam, on which the six deformation modes are imposed via...... Lagrange multipliers. The Lagrange multipliers represent the constraining forces, and thus combine to form the cross-section stiffness matrix. The theory is illustrated by a simple isotropic cross-section....

  8. Superimposition of 3-dimensional cone-beam computed tomography models of growing patients

    Cevidanes, Lucia H. C.; Heymann, Gavin; Cornelis, Marie A.; DeClerck, Hugo J.; Tulloch, J. F. Camilla

    2009-01-01

    Introduction The objective of this study was to evaluate a new method for superimposition of 3-dimensional (3D) models of growing subjects. Methods Cone-beam computed tomography scans were taken before and after Class III malocclusion orthopedic treatment with miniplates. Three observers independently constructed 18 3D virtual surface models from cone-beam computed tomography scans of 3 patients. Separate 3D models were constructed for soft-tissue, cranial base, maxillary, and mandibular surfaces. The anterior cranial fossa was used to register the 3D models of before and after treatment (about 1 year of follow-up). Results Three-dimensional overlays of superimposed models and 3D color-coded displacement maps allowed visual and quantitative assessment of growth and treatment changes. The range of interobserver errors for each anatomic region was 0.4 mm for the zygomatic process of maxilla, chin, condyles, posterior border of the rami, and lower border of the mandible, and 0.5 mm for the anterior maxilla soft-tissue upper lip. Conclusions Our results suggest that this method is a valid and reproducible assessment of treatment outcomes for growing subjects. This technique can be used to identify maxillary and mandibular positional changes and bone remodeling relative to the anterior cranial fossa. PMID:19577154

  9. Limit Analysis of 3D Reinforced Concrete Beam Elements

    Larsen, Kasper P.; Nielsen, Leif Otto; Poulsen, Peter Noe

    2012-01-01

    A new finite-element framework for lower-bound limit analysis of reinforced concrete beams, subjected to loading in three dimensions, is presented. The method circumvents the need for a direct formulation of a complex section-force-based yield criterion by creating a discrete representation of th...

  10. Electro-mechanical coupling of rotating 3D beams

    Stoykov S.

    2016-01-01

    Full Text Available A rotating thin-walled beam with piezoelectric element is analysed. The beam is considered to vibrate in space, hence the longitudinal, transverse and torsional deformations are taken into account. The bending deformations of the beam are modelled by assuming Timoshenko's theory. Torsion is included by considering that the cross section rotates as a rigid body but can deform in longitudinal direction due to warping. The warping function is computed preliminary by the finite element method. The equation of motion is derived by the principle of virtual work and discretized in space by the Ritz method. Electro-mechanical coupling is included in the model by considering the internal electrical energy and the electric charge output. The piezo-electric constitutive relations are used in reduced form. The beam is assumed to rotate about a fixed axis with constant speed. The equation of motion is derived in rotating coordinate system, but the influence of the rotation of the coordinate system is taken into account through the inertia forces. Results in time domain are presented for different speeds of rotation and frequencies of vibration. The influence of the speed of rotation and of the frequency of vibration on the electrical output is presented and analysed.

  11. Cone beam CT for dental and maxillofacial imaging: dose matters.

    Pauwels, Ruben

    2015-07-01

    The widespread use of cone-beam CT (CBCT) in dentistry has led to increasing concern regarding justification and optimisation of CBCT exposures. When used as a substitute to multidetector CT (MDCT), CBCT can lead to significant dose reduction; however, low-dose protocols of current-generation MDCTs show that there is an overlap between CBCT and MDCT doses. More importantly, although the 3D information provided by CBCT can often lead to improved diagnosis and treatment compared with 2D radiographs, a routine or excessive use of CBCT would lead to a substantial increase of the collective patient dose. The potential use of CBCT for paediatric patients (e.g. developmental disorders, trauma and orthodontic treatment planning) further increases concern regarding its proper application. This paper provides an overview of justification and optimisation issues in dental and maxillofacial CBCT. The radiation dose in CBCT will be briefly reviewed. The European Commission's Evidence Based Guidelines prepared by the SEDENTEXCT Project Consortium will be summarised, and (in)appropriate use of CBCT will be illustrated for various dental applications.

  12. Designing a novel dental root analogue implant using cone beam computed tomography and CAD/CAM technology

    Moin, D.A.; Hassan, B.; Mercelis, P.; Wismeijer, D.

    2013-01-01

    Objectives The study aim is to introduce a novel preemptively constructed dental root analogue implant (RAI) based on three-dimensional (3D) root surface models obtained from a cone beam computed tomography (CBCT) scan, computer aided designing and computer aided manufacturing technology. Materials

  13. The accuracy of the imaging reformation of cone beam computed tomography for the assessment of bone defect healing

    Kang, Ho Duk; Kim, Gyu Tae; Choi, Yong Suk; Hwang, Eui Hwan [Kyung Hee Univ., Seoul (Korea, Republic of)

    2007-06-15

    To evaluate the accuracy of the imaging reformation of cone beam computed tomography for the assessment of bone defect healing in rat model. Sprague-Dawely strain rats weighing about 350 gms were selected. Then critical size bone defects were done at parietal bone with implantation of collagen sponge. The rats were divided into seven groups of 3 days, 1 week, 2 weeks, 3 weeks, 4 weeks, 6 weeks, and 8 weeks. The healing of surgical defect was assessed by multiplanar reconstruction (MPR) images and three-dimensional (3-D) images of cone beam computed tomography, compared with soft X-ray radiograph and histopathologic examination. MPR images and 3-D images showed similar reformation of the healing amount at 3 days, 1 week, 2 weeks, and 8 weeks, however, lower reformation at 3 weeks, 4 weeks, and 6 weeks. According to imaging-based methodologies, MPR images revealed similar reformation of the healing mount than 3-D images compare with soft X-ray image. Among the four threshold values for 3-D images, 400-500 HU revealed similar reformation of the healing amount. Histopathologic examination confirmed the newly formed trabeculation correspond with imaging-based mythologies. MPR images revealed higher accuracy of the imaging reformation of cone beam computed tomography and cone beam computed tomography is a clinically useful diagnostic tool for the assessment of bone defect healing.

  14. X-ray cone beam CT system calibration

    Sire, Pascal; Rizo, Philippe; Martin, M.

    1993-12-01

    Recently x-ray cone beam computed tomography (CT) has become of interest for nondestructive testing (NDT) of advanced materials. Such a technique takes advantage of the cone beam geometry, to reduce the acquisition time and increase the resolution. Performances of CT systems rely mainly on geometric precision and measurement quality. Inaccurate geometry or incorrect data produce artifacts and blurring which limit the spatial resolution. A precise geometric calibration procedure is required and some corrections must be applied to the raw attenuation data in order to obtain accurate measurements. An x-ray cone beam CT system has been developed at the LETI. This machine was designed to control small parts limited to a few centimeters, with a high spatial resolution close to 30 microns. This paper introduces the machine setup and describes the calibration computing resources involved in the system. Then, we discuss the performances on experimental data.

  15. 3D Simulations of Space Charge Effects in Particle Beams

    Adelmann, A

    2002-10-01

    For the first time, it is possible to calculate the complicated three-dimensional proton accelerator structures at the Paul Scherrer Institut (PSI). Under consideration are external and self effects, arising from guiding and space-charge forces. This thesis has as its theme the design, implementation and validation of a tracking program for charged particles in accelerator structures. This work form part of the discipline of Computational Science and Engineering (CSE), more specifically in computational accelerator modelling. The physical model is based on the collisionless Vlasov-Maxwell theory, justified by the low density ({approx} 10{sup 9} protons/cm{sup 3}) of the beam and of the residual gas. The probability of large angle scattering between the protons and the residual gas is then sufficiently low, as can be estimated by considering the mean free path and the total distance a particle travels in the accelerator structure. (author)

  16. Influence of scanning and reconstruction parameters on quality of three-dimensional surface models of the dental arches from cone beam computed tomography

    Hassan, B.; Souza, P.C.; Jacobs, R.; Berti, S.D.; van der Stelt, P.

    2010-01-01

    The study aim is to investigate the influence of scan field, mouth opening, voxel size, and segmentation threshold selections on the quality of the three-dimensional (3D) surface models of the dental arches from cone beam computed tomography (CBCT). 3D models of 25 patients scanned with one image in

  17. Composite cone-beam filtered backprojection algorithm based on nutating line

    WANG Yu; OU Zong-ying; SU Tie-ming; WANG Feng

    2006-01-01

    The FDK algorithm is the most popular cone beam algorithm in the medical and industrial imaging field.Due to data insufficiency acquired from a circular trajectory,the images reconstructed by the FDK algorithm suffer from the intensity droping with increasing cone angle.To overcome the drawback,a modified FDK algorithm is presented by convert the 1D ramp filtering direction from along the horizontal lines to along the nutating lines based on the result of Turbell.Unlike Turbell's method,there is no need for our algorithm to rebin the cone-beam data into 3D parallel-beam data before reconstructing.Moreover pre-weighting of the projection data is corrected by compensating for the cone angle effect.In addition,another correction term derived from the result of Hu is also induced into our algorithm.The simulation experiments demonstrate that the final algorithm can suppress the intensity drop associated with the FDK algorithm.

  18. Annular beam shaping system for advanced 3D laser brazing

    Pütsch, Oliver; Stollenwerk, Jochen; Kogel-Hollacher, Markus; Traub, Martin

    2012-10-01

    As laser brazing benefits from advantages such as smooth joints and small heat-affected zones, it has become established as a joining technology that is widely used in the automotive industry. With the processing of complex-shaped geometries, recent developed brazing heads suffer, however, from the need for continuous reorientation of the optical system and/or limited accessibility due to lateral wire feeding. This motivates the development of a laser brazing head with coaxial wire feeding and enhanced functionality. An optical system is designed that allows to generate an annular intensity distribution in the working zone. The utilization of complex optical components avoids obscuration of the optical path by the wire feeding. The new design overcomes the disadvantages of the state-of-the-art brazing heads with lateral wire feeding and benefits from the independence of direction while processing complex geometries. To increase the robustness of the brazing process, the beam path also includes a seam tracking system, leading to a more challenging design of the whole optical train. This paper mainly discusses the concept and the optical design of the coaxial brazing head, and also presents the results obtained with a prototype and selected application results.

  19. Evaluation of the OSC-TV iterative reconstruction algorithm for cone-beam optical CT

    Matenine, Dmitri, E-mail: dmitri.matenine.1@ulaval.ca; Mascolo-Fortin, Julia, E-mail: julia.mascolo-fortin.1@ulaval.ca [Département de physique, de génie physique et d’optique, Université Laval, Québec, Québec G1V 0A6 (Canada); Goussard, Yves, E-mail: yves.goussard@polymtl.ca [Département de génie électrique/Institut de génie biomédical, École Polytechnique de Montréal, C.P. 6079, succ. Centre-ville, Montréal, Québec H3C 3A7 (Canada); Després, Philippe, E-mail: philippe.despres@phy.ulaval.ca [Département de physique, de génie physique et d’optique and Centre de recherche sur le cancer, Université Laval, Québec, Québec G1V 0A6, Canada and Département de radio-oncologie and Centre de recherche du CHU de Québec, Québec, Québec G1R 2J6 (Canada)

    2015-11-15

    Purpose: The present work evaluates an iterative reconstruction approach, namely, the ordered subsets convex (OSC) algorithm with regularization via total variation (TV) minimization in the field of cone-beam optical computed tomography (optical CT). One of the uses of optical CT is gel-based 3D dosimetry for radiation therapy, where it is employed to map dose distributions in radiosensitive gels. Model-based iterative reconstruction may improve optical CT image quality and contribute to a wider use of optical CT in clinical gel dosimetry. Methods: This algorithm was evaluated using experimental data acquired by a cone-beam optical CT system, as well as complementary numerical simulations. A fast GPU implementation of OSC-TV was used to achieve reconstruction times comparable to those of conventional filtered backprojection. Images obtained via OSC-TV were compared with the corresponding filtered backprojections. Spatial resolution and uniformity phantoms were scanned and respective reconstructions were subject to evaluation of the modulation transfer function, image uniformity, and accuracy. The artifacts due to refraction and total signal loss from opaque objects were also studied. Results: The cone-beam optical CT data reconstructions showed that OSC-TV outperforms filtered backprojection in terms of image quality, thanks to a model-based simulation of the photon attenuation process. It was shown to significantly improve the image spatial resolution and reduce image noise. The accuracy of the estimation of linear attenuation coefficients remained similar to that obtained via filtered backprojection. Certain image artifacts due to opaque objects were reduced. Nevertheless, the common artifact due to the gel container walls could not be eliminated. Conclusions: The use of iterative reconstruction improves cone-beam optical CT image quality in many ways. The comparisons between OSC-TV and filtered backprojection presented in this paper demonstrate that OSC-TV can

  20. Respiratory correlated cone-beam computed tomography on an isocentric C-arm

    Kriminski, Sergey [Department of Radiation Oncology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095 (United States); Mitschke, Matthias [Siemens Medical Solutions USA, Inc. Oncology Care Systems, Concord, CA 94520 (United States); Sorensen, Stephen [Department of Radiation Oncology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095 (United States); Wink, Nicole M [Department of Radiation Oncology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095 (United States); Chow, Phillip E [Department of Radiation Oncology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095 (United States); Tenn, Steven [Department of Radiation Oncology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095 (United States); Solberg, Timothy D [Department of Radiation Oncology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095 (United States); Jonsson Comprehensive Cancer Center, Los Angeles, CA 90095 (United States); University of Nebraska Medical Center, Omaha, NE 68102 (United States)

    2005-11-21

    A methodology for 3D image reconstruction from retrospectively gated cone-beam CT projection data has been developed. A mobile x-ray cone-beam device consisting of an isocentric C-arm equipped with a flat panel detector was used to image a moving phantom. Frames for reconstruction were retrospectively selected from complete datasets based on the known rotation of the C-arm and a signal from a respiratory monitor. Different sizes of gating windows were tested. A numerical criterion for blur on the reconstructed image was suggested. The criterion is based on minimization of an Ising energy function, similar to approaches used in image segmentation or restoration. It is shown that this criterion can be used for the determination of the optimal gating window size. Images reconstructed from the retrospectively gated projection sequences using the optimal gating window data showed a significant improvement compared to images reconstructed from the complete projection datasets.

  1. Respiratory correlated cone-beam computed tomography on an isocentric C-arm

    Kriminski, Sergey; Mitschke, Matthias; Sorensen, Stephen; Wink, Nicole M.; Chow, Phillip E.; Tenn, Steven; Solberg, Timothy D.

    2005-11-01

    A methodology for 3D image reconstruction from retrospectively gated cone-beam CT projection data has been developed. A mobile x-ray cone-beam device consisting of an isocentric C-arm equipped with a flat panel detector was used to image a moving phantom. Frames for reconstruction were retrospectively selected from complete datasets based on the known rotation of the C-arm and a signal from a respiratory monitor. Different sizes of gating windows were tested. A numerical criterion for blur on the reconstructed image was suggested. The criterion is based on minimization of an Ising energy function, similar to approaches used in image segmentation or restoration. It is shown that this criterion can be used for the determination of the optimal gating window size. Images reconstructed from the retrospectively gated projection sequences using the optimal gating window data showed a significant improvement compared to images reconstructed from the complete projection datasets.

  2. Endodontic applications of cone beam computed tomography: case series and literature review

    Francesc Abella

    2015-11-01

    Full Text Available Cone beam computed tomography (CBCT is a relatively new method that produces three-dimensional (3D information of the maxillofacial skeleton, including the teeth and their surrounding tissue, with a lower effective radiation dose than traditional CT scans. Specific endodontic applications for CBCT are being identified as the use of this technology becomes more common. CBCT has great potential to become a valuable tool for diagnosing and managing endodontic problems, as well as for assessing root fractures, apical periodontitis, resorptions, perforations, root canal anatomy and the nature of the alveolar bone topography around teeth. This article aims to review cone beam technology and its advantages over CT scans and conventional radiography, to illustrate current and future clinical applications in endodontic practice, and to highlight areas of further research of CBCT in endodontics. Specific case examples illustrate how treatment planning has changed with the images obtained with CBCT technology compared with only periapical radiography.

  3. Use of 3D printers to create a patient-specific 3D bolus for external beam therapy.

    Burleson, Sarah; Baker, Jamie; Hsia, An Ting; Xu, Zhigang

    2015-05-08

    The purpose of this paper is to demonstrate that an inexpensive 3D printer can be used to manufacture patient-specific bolus for external beam therapy, and to show we can accurately model this printed bolus in our treatment planning system for accurate treatment delivery. Percent depth-dose measurements and tissue maximum ratios were used to determine the characteristics of the printing materials, acrylonitrile butadiene styrene and polylactic acid, as bolus material with physical density of 1.04 and 1.2 g/cm3, and electron density of 3.38 × 10²³ electrons/cm3 and 3.80 × 10²³ electrons/ cm3, respectively. Dose plane comparisons using Gafchromic EBT2 film and the RANDO phantom were used to verify accurate treatment planning. We accurately modeled a printing material in Eclipse treatment planning system, assigning it a Hounsfield unit of 260. We were also able to verify accurate treatment planning using gamma analysis for dose plane comparisons. With gamma criteria of 5% dose difference and 2 mm DTA, we were able to have 86.5% points passing, and with gamma criteria of 5% dose difference and 3 mm DTA, we were able to have 95% points passing. We were able to create a patient-specific bolus using an inexpensive 3D printer and model it in our treatment planning system for accurate treatment delivery.

  4. Test Beam Results of 3D Silicon Pixel Sensors for the ATLAS upgrade

    Grenier, P.; /SLAC; Alimonti, G.; /INFN, Milan; Barbero, M.; /Bonn U.; Bates, R.; /Glasgow U.; Bolle, E.; /Oslo U.; Borri, M.; /Manchester U.; Boscardin, M.; /Fond. Bruno Kessler, Povo; Buttar, C.; /Glasgow U.; Capua, M.; /Calabria U. /INFN, Cosenza; Cavalli-Sforza, M.; /Barcelona, IFAE; Cobal, M.; /Udine U. /INFN, Udine; Cristofoli, A.; /Udine U. /INFN, Udine; Dalla Betta, G.F.; /Trento U. /INFN, Trento; Darbo, G.; /INFN, Genoa; Da Via, C.; /Manchester U.; Devetak, E.; /SUNY, Stony Brook; DeWilde, B.; /SUNY, Stony Brook; Di Girolamo, B.; /CERN; Dobos, D.; /CERN; Einsweiler, K.; /LBL, Berkeley; Esseni, D.; /Udine U. /INFN, Udine /Calabria U. /INFN, Cosenza /Barcelona, Inst. Microelectron. /Manchester U. /CERN /LBL, Berkeley /INFN, Genoa /INFN, Genoa /Udine U. /INFN, Udine /Oslo U. /ICREA, Barcelona /Barcelona, IFAE /SINTEF, Oslo /SINTEF, Oslo /SLAC /SLAC /Bergen U. /New Mexico U. /Bonn U. /SLAC /Freiburg U. /VTT Electronics, Espoo /Bonn U. /SLAC /Freiburg U. /SLAC /SINTEF, Oslo /Manchester U. /Barcelona, IFAE /Bonn U. /Bonn U. /CERN /Manchester U. /SINTEF, Oslo /Barcelona, Inst. Microelectron. /Calabria U. /INFN, Cosenza /Udine U. /INFN, Udine /Manchester U. /VTT Electronics, Espoo /Glasgow U. /Barcelona, IFAE /Udine U. /INFN, Udine /Hawaii U. /Freiburg U. /Manchester U. /Barcelona, Inst. Microelectron. /CERN /Fond. Bruno Kessler, Povo /Prague, Tech. U. /Trento U. /INFN, Trento /CERN /Oslo U. /Fond. Bruno Kessler, Povo /INFN, Genoa /INFN, Genoa /Bergen U. /New Mexico U. /Udine U. /INFN, Udine /SLAC /Oslo U. /Prague, Tech. U. /Oslo U. /Bergen U. /SUNY, Stony Brook /SLAC /Calabria U. /INFN, Cosenza /Manchester U. /Bonn U. /SUNY, Stony Brook /Manchester U. /Bonn U. /SLAC /Fond. Bruno Kessler, Povo

    2011-08-19

    Results on beam tests of 3D silicon pixel sensors aimed at the ATLAS Insertable-B-Layer and High Luminosity LHC (HL-LHC) upgrades are presented. Measurements include charge collection, tracking efficiency and charge sharing between pixel cells, as a function of track incident angle, and were performed with and without a 1.6 T magnetic field oriented as the ATLAS Inner Detector solenoid field. Sensors were bump bonded to the front-end chip currently used in the ATLAS pixel detector. Full 3D sensors, with electrodes penetrating through the entire wafer thickness and active edge, and double-sided 3D sensors with partially overlapping bias and read-out electrodes were tested and showed comparable performance. Full and partial 3D pixel detectors have been tested, with and without a 1.6T magnetic field, in high energy pion beams at the CERN SPS North Area in 2009. Sensors characteristics have been measured as a function of the beam incident angle and compared to a regular planar pixel device. Overall full and partial 3D devices have similar behavior. Magnetic field has no sizeable effect on 3D performances. Due to electrode inefficiency 3D devices exhibit some loss of tracking efficiency for normal incident tracks but recover full efficiency with tilted tracks. As expected due to the electric field configuration 3D sensors have little charge sharing between cells.

  5. Cone beam computed tomography in Endodontics - a review

    Patel, S.; Durack, C.; Abella, F.; Shemesh, H.; Roig, M.; Lemberg, K.

    2015-01-01

    Cone beam computed tomography (CBCT) produces undistorted three-dimensional information of the maxillofacial skeleton, including the teeth and their surrounding tissues with a lower effective radiation dose than computed tomography. The aim of this paper is to: (i) review the current literature on t

  6. Operator radiation exposure in cone-beam computed tomography guidance

    Braak, S.J.; Strijen Van, M. J L; Meijer, E.; Heesewijk Van, J. P M; Mali, W. P T M

    2016-01-01

    Objectives: Quantitative analysis of operator dose in cone-beam computed tomography guidance (CBCT-guidance) and the effect of protective shielding. Methods: Using a Rando phantom, a model was set-up to measure radiation dose for the operator hand, thyroid and gonad region. The effect of sterile rad

  7. Filtered region of interest cone-beam rotational angiography

    Schafer, Sebastian; Noeel, Peter B.; Walczak, Alan M.; Hoffmann, Kenneth R. [Department of Mechanical Engineering, SUNY at Buffalo, 3435 Main Street, Buffalo, New York 14214 (United States); Department of Neurosurgery, SUNY at Buffalo, 3435 Main Street, Buffalo, New York 14214 (United States) and Toshiba Stroke Research Center, SUNY at Buffalo, 3435 Main Street, Buffalo, New York 14214 (United States); Department of Neurosurgery, SUNY at Buffalo, 3435 Main Street, Buffalo, New York 14214 (United States); Department of Computer Science, SUNY at Buffalo, 3435 Main Street, Buffalo, New York 14214 (United States) and Toshiba Stroke Research Center, SUNY at Buffalo, 3435 Main Street, Buffalo, New York 14214 (United States); Department of Neurosurgery, SUNY at Buffalo, 3435 Main Street, Buffalo, New York 14214 and Toshiba Stroke Research Center, SUNY at Buffalo, 3435 Main Street, Buffalo, New York 14214 (United States); Department of Mechanical Engineering, SUNY at Buffalo, 3435 Main Street, Buffalo, New York 14214 (United States); Department of Neurosurgery, SUNY at Buffalo, 3435 Main Street, Buffalo, New York 14214 (United States); Department of Computer Science, SUNY at Buffalo, 3435 Main Street, Buffalo, New York 14214 (United States) and Toshiba Stroke Research Center, SUNY at Buffalo, 3435 Main Street, Buffalo, New York 14214 (United States)

    2010-02-15

    Purpose: Cone-beam rotational angiography (CBRA) is widely used in the modern clinical settings. In a number of procedures, the area of interest is often considerably smaller than the field of view (FOV) of the detector, subjecting the patient to potentially unnecessary x-ray dose. The authors therefore propose a filter-based method to reduce the dose in the regions of low interest, while supplying high image quality in the region of interest (ROI). Methods: For such procedures, the authors propose a method of filtered region of interest (FROI)-CBRA. In the authors' approach, a gadolinium filter with a circular central opening is placed into the x-ray beam during image acquisition. The central region is imaged with high contrast, while peripheral regions are subjected to a substantial lower intensity and dose through beam filtering. The resulting images contain a high contrast/intensity ROI, as well as a low contrast/intensity peripheral region, and a transition region in between. To equalize the two regions' intensities, the first projection of the acquisition is performed with and without the filter in place. The equalization relationship, based on Beer's law, is established through linear regression using corresponding filtered and nonfiltered data. The transition region is equalized based on radial profiles. Results: Evaluations in 2D and 3D show no visible difference between conventional FROI-CBRA projection images and reconstructions in the ROI. CNR evaluations show similar image quality in the ROI, with a reduced CNR in the reconstructed peripheral region. In all filtered projection images, the scatter fraction inside the ROI was reduced. Theoretical and experimental dose evaluations show a considerable dose reduction; using a ROI half the original FOV reduces the dose by 60% for the filter thickness of 1.29 mm. Conclusions: These results indicate the potential of FROI-CBRA to reduce the dose to the patient while supplying the physician with

  8. CT thermometry for cone-beam CT guided ablation

    DeStefano, Zachary; Abi-Jaoudeh, Nadine; Li, Ming; Wood, Bradford J.; Summers, Ronald M.; Yao, Jianhua

    2016-03-01

    Monitoring temperature during a cone-beam CT (CBCT) guided ablation procedure is important for prevention of over-treatment and under-treatment. In order to accomplish ideal temperature monitoring, a thermometry map must be generated. Previously, this was attempted using CBCT scans of a pig shoulder undergoing ablation.1 We are extending this work by using CBCT scans of real patients and incorporating more processing steps. We register the scans before comparing them due to the movement and deformation of organs. We then automatically locate the needle tip and the ablation zone. We employ a robust change metric due to image noise and artifacts. This change metric takes windows around each pixel and uses an equation inspired by Time Delay Analysis to calculate the error between windows with the assumption that there is an ideal spatial offset. Once the change map is generated, we correlate change data with measured temperature data at the key points in the region. This allows us to transform our change map into a thermal map. This thermal map is then able to provide an estimate as to the size and temperature of the ablation zone. We evaluated our procedure on a data set of 12 patients who had a total of 24 ablation procedures performed. We were able to generate reasonable thermal maps with varying degrees of accuracy. The average error ranged from 2.7 to 16.2 degrees Celsius. In addition to providing estimates of the size of the ablation zone for surgical guidance, 3D visualizations of the ablation zone and needle are also produced.

  9. Applying microCT and 3D Visualization to Jurassic Silicified Conifer Seed Cones: A Virtual Advantage Over Thin-Sectioning

    Carole T. Gee

    2013-11-01

    Full Text Available Premise of the study: As an alternative to conventional thin-sectioning, which destroys fossil material, high-resolution X-ray computed tomography (also called microtomography or microCT integrated with scientific visualization, three-dimensional (3D image segmentation, size analysis, and computer animation is explored as a nondestructive method of imaging the internal anatomy of 150-million-year-old conifer seed cones from the Late Jurassic Morrison Formation, USA, and of recent and other fossil cones. Methods: MicroCT was carried out on cones using a General Electric phoenix v|tome|x s 240D, and resulting projections were processed with visualization software to produce image stacks of serial single sections for two-dimensional (2D visualization, 3D segmented reconstructions with targeted structures in color, and computer animations. Results: If preserved in differing densities, microCT produced images of internal fossil tissues that showed important characters such as seed phyllotaxy or number of seeds per cone scale. Color segmentation of deeply embedded seeds highlighted the arrangement of seeds in spirals. MicroCT of recent cones was even more effective. Conclusions: This is the first paper on microCT integrated with 3D segmentation and computer animation applied to silicified seed cones, which resulted in excellent 2D serial sections and segmented 3D reconstructions, revealing features requisite to cone identification and understanding of strobilus construction.

  10. Diversity and Multiplexing Technologies by 3D Beams in Polarized Massive MIMO Systems

    Xin Su

    2016-01-01

    Full Text Available Massive multiple input, multiple output (M-MIMO technologies have been proposed to scale up data rates reaching gigabits per second in the forthcoming 5G mobile communications systems. However, one of crucial constraints is a dimension in space to implement the M-MIMO. To cope with the space constraint and to utilize more flexibility in 3D beamforming (3D-BF, we propose antenna polarization in M-MIMO systems. In this paper, we design a polarized M-MIMO (PM-MIMO system associated with 3D-BF applications, where the system architectures for diversity and multiplexing technologies achieved by polarized 3D beams are provided. Different from the conventional 3D-BF achieved by planar M-MIMO technology to control the downtilted beam in a vertical domain, the proposed PM-MIMO realizes 3D-BF via the linear combination of polarized beams. In addition, an effective array selection scheme is proposed to optimize the beam-width and to enhance system performance by the exploration of diversity and multiplexing gains; and a blind channel estimation (BCE approach is also proposed to avoid pilot contamination in PM-MIMO. Based on the Long Term Evolution-Advanced (LTE-A specification, the simulation results finally confirm the validity of our proposals.

  11. Study of effective dose of various protocols in equipment cone beam CT

    Soares, M. R.; Maia, A. F. [Universidade Federale de Sergipe, Departamento de Fisica, Cidade Universitaria Prof. Jose Aloisio de Campos, Marechal Rondon s/n, Jardim Rosa Elze, 49-100000 Sao Cristovao, Sergipe (Brazil); Batista, W. O. [Instituto Federal da Bahia, Rua Emidio dos Santos s/n, Barbalho, Salvador, 40301015 Bahia (Brazil); Caldas, L. V. E.; Lara, P. A., E-mail: mrs2206@gmail.com [Instituto de Pesquisas Energeticas e Nucleares / CNEN, Av. Lineu Prestes 2242, Cidade Universitaria, 05508-000 Sao Paulo (Brazil)

    2014-08-15

    Currently the cone beam computed tomography is widely used in various procedures of dental radiology. Although the doses values associated with the procedures of cone beam CT are low compared to typical values associated with dental radiology procedure in multi slices CT. However can be high compared to typical values of other techniques commonly used in dental radiology. The present scenario is a very wide range of designs of equipment and, consequently, lack of uniformity in all parameters associated with x-ray generation and geometry. In this context, this study aimed to evaluate and calculate the absorbed dose in organs and tissues relevant and estimate effective dose for different protocols with different geometries of exposure in five cone beam CT equipment. For this, a female Alderson anthropomorphic phantom, manufactured by Radiology Support Devices was used. The phantom was irradiated with 26 dosimeters LiF: Mg, Ti (TLD-100), inserted in organs and tissues along the layers forming the head and neck of the phantom. The equipment used, in this present assessment, was: i-CAT Classical, Kodak 9000 3D, Gendex GXCB 500, Sirona Orthophos X G 3D and Planmeca Pro Max 3D. The effective doses were be determined by the ICRP 103 weighting factors. The values were between 7.0 and 111.5 micro Sv, confirming the broad dose range expected due to the diversity of equipment and protocols used in each equipment. The values of effective dose per Fov size were: between 7 and 51.2 micro Sv for located Fov; between 17.6 and 52.0 micro Sv for medium Fov; and between 11.5 and 43.1 micro Sv to large Fov (maxillofacial). In obtaining the effective dose the measurements highlighted a relevance contribution of dose absorbed by the remaining organs (36%), Salivary glands (30%), thyroid (12%) and bone marrow (12%). (Author)

  12. Cone beam computed tomography radiation dose and image quality assessments.

    Lofthag-Hansen, Sara

    2010-01-01

    Diagnostic radiology has undergone profound changes in the last 30 years. New technologies are available to the dental field, cone beam computed tomography (CBCT) as one of the most important. CBCT is a catch-all term for a technology comprising a variety of machines differing in many respects: patient positioning, volume size (FOV), radiation quality, image capturing and reconstruction, image resolution and radiation dose. When new technology is introduced one must make sure that diagnostic accuracy is better or at least as good as the one it can be expected to replace. The CBCT brand tested was two versions of Accuitomo (Morita, Japan): 3D Accuitomo with an image intensifier as detector, FOV 3 cm x 4 cm and 3D Accuitomo FPD with a flat panel detector, FOVs 4 cm x 4 cm and 6 cm x 6 cm. The 3D Accuitomo was compared with intra-oral radiography for endodontic diagnosis in 35 patients with 46 teeth analyzed, of which 41 were endodontically treated. Three observers assessed the images by consensus. The result showed that CBCT imaging was superior with a higher number of teeth diagnosed with periapical lesions (42 vs 32 teeth). When evaluating 3D Accuitomo examinations in the posterior mandible in 30 patients, visibility of marginal bone crest and mandibular canal, important anatomic structures for implant planning, was high with good observer agreement among seven observers. Radiographic techniques have to be evaluated concerning radiation dose, which requires well-defined and easy-to-use methods. Two methods: CT dose index (CTDI), prevailing method for CT units, and dose-area product (DAP) were evaluated for calculating effective dose (E) for both units. An asymmetric dose distribution was revealed when a clinical situation was simulated. Hence, the CTDI method was not applicable for these units with small FOVs. Based on DAP values from 90 patient examinations effective dose was estimated for three diagnostic tasks: implant planning in posterior mandible and

  13. Automated volume of interest delineation and rendering of cone beam CT images in interventional cardiology

    Lorenz, Cristian; Schäfer, Dirk; Eshuis, Peter; Carroll, John; Grass, Michael

    2012-02-01

    Interventional C-arm systems allow the efficient acquisition of 3D cone beam CT images. They can be used for intervention planning, navigation, and outcome assessment. We present a fast and completely automated volume of interest (VOI) delineation for cardiac interventions, covering the whole visceral cavity including mediastinum and lungs but leaving out rib-cage and spine. The problem is addressed in a model based approach. The procedure has been evaluated on 22 patient cases and achieves an average surface error below 2mm. The method is able to cope with varying image intensities, varying truncations due to the limited reconstruction volume, and partially with heavy metal and motion artifacts.

  14. Should cavitation in proximal surfaces be reported in cone beam computed tomography examination?

    Sansare, K; Singh, D; Sontakke, S

    2014-01-01

    Aim: A clinical study was done to assess the clinical diagnostic accuracy of cone beam computed tomography (CBCT) in detecting proximal cavitated carious lesions in order to determine whether cavitation should be reported when a CBCT examination is available. Materials and Methods: 79 adjacent...... proximal surfaces without restorations in permanent teeth were examined. Patients suspected to have carious lesions after a visual clinical and a bitewing examination participated in a CBCT examination (Kodak 9000 3D, 5 × 3.7 cm field of view, voxel size 0.07 mm). Ethical approval and informed consent were...

  15. La tomografía computarizada cone beam en la ortodoncia, ortopedia facial y funcional

    Roque-Torres,Gina D.; Meneses-López, Abraham; Norberto Bóscolo, Frab; De Almeida, Solange María; HAITER NETO Francisco

    2015-01-01

    La Tomografía Computarizada Cone Beam (TCCB) es una tecnología en rápido desarrollo que proporciona imágenes de alta resolución espacial del complejo craneofacial en tres dimensiones (3D). Durante la última década, el número de publicaciones relacionadas a la TCCB en la literatura se ha incrementado de manera significativa, pero la cuestión fundamental es si esta tecnología conduce a mejores resultados. La TCCB y su aplicación en la ortodoncia es muy importante ya que esta nueva tecnología va...

  16. Enhancement of breast calcification visualization and detection using a modified PG method in Cone Beam Breast CT.

    Liu, Jiangkun; Ning, Ruola; Cai, Weixing; Benitez, Ricardo Betancourt

    2012-01-01

    Cone Beam Breast CT is a promising diagnostic modality in breast imaging. Its isotropic 3D spatial resolution enhances the characterization of micro-calcifications in breasts that might not be easily distinguishable in mammography. However, due to dose level considerations, it is beneficial to further enhance the visualization of calcifications in Cone Beam Breast CT images that might be masked by noise. In this work, the Papoulis-Gerchberg method was modified and implemented in Cone Beam Breast CT images to improve the visualization and detectability of calcifications. First, the PG method was modified and applied to the projections acquired during the scanning process; its effects on the reconstructed images were analyzed by measuring the Modulation Transfer Function and the Noise Power Spectrum. Second, Cone Beam Breast CT images acquired at different dose levels were pre-processed using this technique to enhance the visualization of calcification. Finally, a computer-aided diagnostic algorithm was utilized to evaluate the efficacy of this method to improve calcification detectability. The results demonstrated that this technique can effectively improve image quality by improving the Modulation Transfer Function with a minor increase in noise level. Consequently, the visualization and detectability of calcifications were improved in Cone Beam Breast CT images. This technique was also proved to be useful in reducing the x-ray dose without degrading visualization and detectability of calcifications.

  17. [Change in condylar and mandibular morphology in juvenile idiopathic arthritis: cone beam volumetric imaging].

    Garagiola, Umberto; Mercatali, Lorenzo; Bellintani, Claudio; Fodor, Attila; Farronato, Giampietro; Lőrincz, Adám

    2013-03-01

    The aim of this study is to show the importance of Cone Beam Computerized Tomography to volumetrically quantify TMJ damage in patients with JIA, measuring condylar and mandibular real volumes. 34 children with temporomandibular involvement by Juvenile Idiopathic Arthritis were observed by Cone Beam Computerized Tomography. 4 were excluded because of several imaging noises. The mandible was isolated from others craniofacial structures; the whole mandibular volume and its components' volumes (condyle, ramus, hemibody, hemisymphysis on right side and on left side) has been calculated by a 3D volume rendering technique. The results show a highly significant statistical difference between affected side volumetric values versus normal side volumetric values above all on condyle region (P < 0.01), while they don't show any statistical differences between right side versus left side. The Cone Beam Computerized Tomography represents a huge improvement in understanding of the condyle and mandibular morphological changes, even in the early stages of the Juvenile Idiopathic Arthritis. The JIA can lead in children to temporomandibular joint damage with facial development and growth alterations.

  18. Marker-free lung tumor trajectory estimation from a cone beam CT sinogram

    Hugo, Geoffrey D.; Liang, Jian; Yan, Di

    2010-05-01

    An algorithm was developed to estimate the 3D lung tumor position using the projection data forming a cone beam CT sinogram and a template registration method. A pre-existing respiration-correlated CT image was used to generate templates of the target, which were then registered to the individual cone beam CT projections, and estimates of the target position were made for each projection. The registration search region was constrained based on knowledge of the mean tumor position during the cone beam CT scan acquisition. Several template registration algorithms were compared, including correlation coefficient and robust methods such as block correlation, robust correlation coefficient and robust gradient correlation. Robust registration metrics were found to be less sensitive to occlusions such as overlying tissue and the treatment couch. The mean accuracy of the position estimation was 1.4 mm in phantom with a robust registration algorithm. In two research subjects with peripheral tumors, the mean position and mean target excursion were estimated to within 2.0 mm compared to the results obtained with a '4D' registration of 4D image volumes.

  19. Terahertz imaging system based on bessel beams via 3D printed axicons at 100GHz

    Liu, Changming; Wei, Xuli; Zhang, Zhongqi; Wang, Kejia; Yang, Zhenggang; Liu, Jinsong

    2014-11-01

    Terahertz (THz) imaging technology shows great advantage in nondestructive detection (NDT), since many optical opaque materials are transparent to THz waves. In this paper, we design and fabricate dielectric axicons to generate zeroth order-Bessel beams by 3D printing technology. We further present an all-electric THz imaging system using the generated Bessel beams in 100GHz. Resolution targets made of printed circuit board are imaged, and the results clearly show the extended depth of focus of Bessel beam, indicating the promise of Bessel beam for the THz NDT.

  20. Tomografía computarizada Cone Beam en endodoncia.

    Oviedo Muñoz, Pámela; Facultad de Estomatología. Universidad Peruana Cayetano Heredia. Lima,; Hernández Añaños, Juan Felipe; Facultad de Estomatología, Universidad Peruana Cayetano Heredia. Lima,

    2014-01-01

    La tomografía computarizada Cone Beam gracias a los avances tecnológicos esta especialmente diseñada para producir imágenes de alta resolución e información tridimensional para aplicaciones dentales, esta tiene ventajas en la detección de los signos clínicos y la precisión en el diagnóstico. Además reduce el tiempo de exploración y sobre todo reduce la dosis de radiación en comparación de la tomografía computarizada tradicional.La tomografía computarizada Cone Beam y su aplicación en la endod...

  1. Cone beam CT in radiology; DVT in der Radiologie

    Dammann, Florian [ALB FILS KLINIKEN GmbH, Klinik am Eichert, Goeppingen (Germany). Inst. fuer Radiologie

    2013-06-15

    Cone beam computed tomography (CBCT) is a cross-sectional X-ray modality using an imaging system with cone-beam geometry. Unlike CT, the data set is acquired in a single circulation of a C-arm shaped tube-detector unit. Image characteristics vs. exposure dose ratio is similar to conventional CT, but varies widely depending on the CBVT device and the selected settings, and is limited to low dose/high noise applications. Up to now, only few data is available to estimate the clinical value of CBCT. Nevertheless, the use of CBCT is increasing drastically in the recent years, especially in the dental and ENT diagnostic field. For this reason the European Commission recently published guidelines concerning the clinical application of CBCT. These guidelines, as well as clinically relevant technical features of CBCT and examples of the most frequent dental applications are presented in the following article. (orig.)

  2. Mandibular condyle position in cone beam computed tomography

    Hwang, Hyoung Joo; Kim, Gyu Tae; Choi, Yong Suk; Hwang, Eui Hwan [Kyung Hee Univ. School of Dentistry, Seoul (Korea, Republic of)

    2006-06-15

    To evaluate position of the mandibular condyle within articular fossa in an asymptomatic population radiographically by a cone beam computed tomography. Cone beam computed tomography of 60 temporomandibular joints was performed on 15 males and 15 females with no history of any temporomandibular disorders, or any other orthodontic or photoconductors treatments. Position of mandibular condyle within articular fossa at centric occlusion was evaluated. A statistical evaluation was done using a SPSS. In the sagittal views, mandibular condyle within articular fossa was laterally located at central section. Mandibular condyles in the right and left sides were showed asymmetric positional relationship at medial, central, and lateral sections. Mandibular condyle within articular fossa in an asymptomatic population was observed non-concentric position in the sagittal and coronal views.

  3. Cone beam CT in orthodontics: the current picture.

    Makdissi, Jimmy

    2013-03-01

    The introduction of cone beam computed tomography (CBCT) technology to dentistry and orthodontics revolutionized the diagnosis, treatment and monitoring of orthodontic patients. This review article discusses the use of CBCT in diagnosis and treatment planning in orthodontics. The steps required to install and operate a CBCT facility within the orthodontic practice as well as the challenges are highlighted. The available guidelines in relation to the clinical applications of CBCT in orthodontics are explored.

  4. Cone beam computed tomography in Endodontics - a review.

    Patel, S; Durack, C; Abella, F; Shemesh, H; Roig, M; Lemberg, K

    2015-01-01

    Cone beam computed tomography (CBCT) produces undistorted three-dimensional information of the maxillofacial skeleton, including the teeth and their surrounding tissues with a lower effective radiation dose than computed tomography. The aim of this paper is to: (i) review the current literature on the applications and limitations of CBCT; (ii) make recommendations for the use of CBCT in Endodontics; (iii) highlight areas of further research of CBCT in Endodontics.

  5. A Clinical Evaluation of Cone Beam Computed Tomography

    2013-07-31

    multidetector computed tomography and cone beam computed tomography in the assessment of dental implant site dimensions. Dentomaxillofac Radiol 2011;40:67-75...submitted to the Faculty of the Endodontics Graduate Program Naval Postgraduate Dental School Uniformed Services University of the Health Sciences...in partial fulfillment of the requirements of the degree of Master of Science in Oral Biology June 2013 Naval Postgraduate Dental

  6. Industrial challenges in ion beam processing and metrology in the 3D era

    England, J.; Möller, W.

    2015-12-01

    Ion beam mechanisms present in plasma doping have been investigated by comparing SIMS measurements of Ge implants into deposited layers of As on Si wafers to planar dynamic ion beam models of the implants and SIMS analyses. Industrial devices are overcoming the limitations of lateral scaling by using the vertical direction. The same modelling approach would be valuable for interpreting 1.5D SIMS analyses of plasma doping of 3D-NAND test structures but 3D dynamic codes do not yet have all the capabilities to allow this. The required features are being developed within a static 3D code, TRI3DSTP, which has been used to qualitatively explain the good uniformity of a P plasma doping process and indicate where more quantitative explanations will be possible once the full dynamic capabilities are available.

  7. Industrial challenges in ion beam processing and metrology in the 3D era

    England, J., E-mail: jonathan_england@amat.com [Varian Semiconductor Equipment, Silicon Systems Group, Applied Materials Inc. (United States); Möller, W. [Helmholtz-Zentrum Dresden-Rossendorf, Institute of Ion Beam Physics and Materials Research, Bautzner Landstrasse 400, 01328 Dresden (Germany)

    2015-12-15

    Ion beam mechanisms present in plasma doping have been investigated by comparing SIMS measurements of Ge implants into deposited layers of As on Si wafers to planar dynamic ion beam models of the implants and SIMS analyses. Industrial devices are overcoming the limitations of lateral scaling by using the vertical direction. The same modelling approach would be valuable for interpreting 1.5D SIMS analyses of plasma doping of 3D-NAND test structures but 3D dynamic codes do not yet have all the capabilities to allow this. The required features are being developed within a static 3D code, TRI3DSTP, which has been used to qualitatively explain the good uniformity of a P plasma doping process and indicate where more quantitative explanations will be possible once the full dynamic capabilities are available.

  8. Anatomical structure of lingual foramen in cone beam computed tomography

    Ki, Min Woo; Hwang, Eui Hwan; Lee, Sang Rae [Kyunghee University College of Medicine, Seoul (Korea, Republic of)

    2004-07-15

    To evaluate whether cone beam computed tomography can depict the distribution, position, frequency, relative vertical dimension, and the diameter of the lingual foramen and direction of lingual bone canal. Cone beam computed tomography of mandible was performed on 25 males and 25 females with no history of any orthodontic treatments or any other dental surgeries. A statistical comparison was done on the mean values of males and females. In the location and distribution of lingual foramina, median lingual foramen was found in all subjects and lateral lingual foramen in 58%. In the lateral lingual foramen, bilateral type was found in 28% and unilateral type in 30%. In the number of lingual foramina, median lingual foramen had two foramina and lateral lingual foramen had one foramen, mostly. In the relative mean vertical dimension of lingual foramina, median lingual foramen was 0.03 {+-} 0.08, and both lateral lingual foramina was 0.20 {+-} 0.04. The mean diameter of lingual foramina, median lingual foramen was 0.9 mm {+-} 0.28, right lateral lingual foramen was 0.92 mm {+-} 0.23, and left lateral lingual foramen was 0.88 mm {+-} 0.27. The most frequent direction of the lingual bone canals, median lingual bone canal proceeded in anteroinferior direction and lateral lingual bone canal in anterosuperolateral direction. Cone beam computed tomography can be helpful for surgery and implantation on the mandibular area. Radiologist should be aware of this anatomical feature and its possible implications.

  9. Development of Focused Ion Beam technique for high speed steel 3D-SEM artefact fabrication

    Carli, Lorenzo; MacDonald, A. Nicole; De Chiffre, Leonardo

    2009-01-01

    The work describes preliminary manufacture by grinding, followed by machining on a Focused Ion Beam (FIB), of a high speed steel step artefact for 3D-SEM calibration. The FIB is coupled with a SEM in the so called dual beam instrument. The milling capabilities of FIB were checked from a qualitati...... point of view, using the dual beam SEM imaging, and quantitatively using a reference stylus instrument, to establish traceability. A triangular section having a depth of about 10 μm was machined, where the 50 μm curvature radius due to grinding was reduced to about 2 μm by FIB milling...

  10. Upper airway alterations/abnormalities in a case series of obstructive sleep apnea patients identified with cone-beam CT

    Shigeta, Y.; Shintaku, W.H.; Clark, G.T. [Orofacial Pain/Oral Medicine Center, Div. of Diagnostic Sciences, School of Dentistry, Univ. of Southern California, Los Angeles, CA (United States); Enciso, R. [Div. of Craniofacial Sciences and Therapeutics, School of Dentistry, Univ. of Southern California, Los Angeles, CA (United States); Ogawa, T. [Dept. of Fixed Prosthodontic Dentistry, Tsurumi Univ., School of Dental Medicine, Tsurumi (Japan)

    2007-06-15

    There are many factors that influence the configuration of the upper airway and may contribute to the development of obstructive sleep apnea (OSA). This paper presents a series of 12 consecutive OSA cases where various upper airway alteration/abnormalities were identified using 3D anatomic reconstructions generated from cone-beam CT (CBCT) images. Some cases exhibited more than one type of abnormality and below we describe each of the six types identified with CBCT in this case series. (orig.)

  11. Reduction of Cone-Beam CT scan time without compromising the accuracy of the image registration in IGRT

    Westberg, Jonas; Jensen, Henrik R; Bertelsen, Anders;

    2010-01-01

    In modern radiotherapy accelerators are equipped with 3D cone-beam CT (CBCT) which is used to verify patient position before treatment. The verification is based on an image registration between the CBCT acquired just before treatment and the CT scan made for the treatment planning. The purpose...... of this study is to minimise the scan time of the CBCT without compromising the accuracy of the image registration in IGRT....

  12. Commissioning kilovoltage cone-beam CT beams in a radiation therapy treatment planning system.

    Alaei, Parham; Spezi, Emiliano

    2012-11-08

    The feasibility of accounting of the dose from kilovoltage cone-beam CT in treatment planning has been discussed previously for a single cone-beam CT (CBCT) beam from one manufacturer. Modeling the beams and computing the dose from the full set of beams produced by a kilovoltage cone-beam CT system requires extensive beam data collection and verification, and is the purpose of this work. The beams generated by Elekta X-ray volume imaging (XVI) kilovoltage CBCT (kV CBCT) system for various cassettes and filters have been modeled in the Philips Pinnacle treatment planning system (TPS) and used to compute dose to stack and anthropomorphic phantoms. The results were then compared to measurements made using thermoluminescent dosimeters (TLDs) and Monte Carlo (MC) simulations. The agreement between modeled and measured depth-dose and cross profiles is within 2% at depths beyond 1 cm for depth-dose curves, and for regions within the beam (excluding penumbra) for cross profiles. The agreements between TPS-calculated doses, TLD measurements, and Monte Carlo simulations are generally within 5% in the stack phantom and 10% in the anthropomorphic phantom, with larger variations observed for some of the measurement/calculation points. Dose computation using modeled beams is reasonably accurate, except for regions that include bony anatomy. Inclusion of this dose in treatment plans can lead to more accurate dose prediction, especially when the doses to organs at risk are of importance.

  13. Comparative analysis between mandibular positions in centric relation and maximum intercuspation by cone beam computed tomography (CONE-BEAM).

    Ferreira, Amanda de Freitas; Henriques, João César Guimarães; Almeida, Guilherme Araújo; Machado, Asbel Rodrigues; Machado, Naila Aparecida de Godoi; Fernandes Neto, Alfredo Júlio

    2009-01-01

    This research consisted of a quantitative assessment, and aimed to measure the possible discrepancies between the maxillomandibular positions for centric relation (CR) and maximum intercuspation (MI), using computed tomography volumetric cone beam (cone beam method). The sample of the study consisted of 10 asymptomatic young adult patients divided into two types of standard occlusion: normal occlusion and Angle Class I occlusion. In order to obtain the centric relation, a JIG device and mandible manipulation were used to deprogram the habitual conditions of the jaw. The evaluations were conducted in both frontal and lateral tomographic images, showing the condyle/articular fossa relation. The images were processed in the software included in the NewTom 3G device (QR NNT software version 2.00), and 8 tomographic images were obtained per patient, four laterally and four frontally exhibiting the TMA's (in CR and MI, on both sides, right and left). By means of tools included in another software, linear and angular measurements were performed and statistically analyzed by student t test. According to the methodology and the analysis performed in asymptomatic patients, it was not possible to detect statistically significant differences between the positions of centric relation and maximum intercuspation. However, the resources of cone beam tomography are of extreme relevance to the completion of further studies that use heterogeneous groups of samples in order to compare the results.

  14. Comparative analysis between mandibular positions in centric relation and maximum intercuspation by cone beam computed tomography (CONE-BEAM

    Amanda de Freitas Ferreira

    2009-01-01

    Full Text Available This research consisted of a quantitative assessment, and aimed to measure the possible discrepancies between the maxillomandibular positions for centric relation (CR and maximum intercuspation (MI, using computed tomography volumetric cone beam (cone beam method. The sample of the study consisted of 10 asymptomatic young adult patients divided into two types of standard occlusion: normal occlusion and Angle Class I occlusion. In order to obtain the centric relation, a JIG device and mandible manipulation were used to deprogram the habitual conditions of the jaw. The evaluations were conducted in both frontal and lateral tomographic images, showing the condyle/articular fossa relation. The images were processed in the software included in the NewTom 3G device (QR NNT software version 2.00, and 8 tomographic images were obtained per patient, four laterally and four frontally exhibiting the TMA's (in CR and MI, on both sides, right and left. By means of tools included in another software, linear and angular measurements were performed and statistically analyzed by student t test. According to the methodology and the analysis performed in asymptomatic patients, it was not possible to detect statistically significant differences between the positions of centric relation and maximum intercuspation. However, the resources of cone beam tomography are of extreme relevance to the completion of further studies that use heterogeneous groups of samples in order to compare the results.

  15. The use of cone-beam computed tomography in an orthodontic department in between research and daily clinic.

    Cattaneo, Paolo M; Melsen, Birte

    2008-01-01

    A correct orthodontic diagnosis needs to be based on accurate images of the craniofacial region and is crucial for the development of a valid treatment plan. A cone-beam computed tomography (CBCT) scanner allows 3D imaging of the craniofacial complex. CBCT scanners represent a significant advantage in imaging capabilities for dentistry and orthodontics, replacing conventional 2D radiographic images with 3D data sets and only a small increase in radiation. The present study surveys the rationale, advantages, and disadvantages of the available CBCT appliances and presents answers to questions often asked in relation to this technology.

  16. High-purity 3D nano-objects grown by focused-electron-beam induced deposition

    Córdoba, Rosa; Sharma, Nidhi; Kölling, Sebastian; Koenraad, Paul M.; Koopmans, Bert

    2016-09-01

    To increase the efficiency of current electronics, a specific challenge for the next generation of memory, sensing and logic devices is to find suitable strategies to move from two- to three-dimensional (3D) architectures. However, the creation of real 3D nano-objects is not trivial. Emerging non-conventional nanofabrication tools are required for this purpose. One attractive method is focused-electron-beam induced deposition (FEBID), a direct-write process of 3D nano-objects. Here, we grow 3D iron and cobalt nanopillars by FEBID using diiron nonacarbonyl Fe2(CO)9, and dicobalt octacarbonyl Co2(CO)8, respectively, as starting materials. In addition, we systematically study the composition of these nanopillars at the sub-nanometer scale by atom probe tomography, explicitly mapping the homogeneity of the radial and longitudinal composition distributions. We show a way of fabricating high-purity 3D vertical nanostructures of ˜50 nm in diameter and a few micrometers in length. Our results suggest that the purity of such 3D nanoelements (above 90 at% Fe and above 95 at% Co) is directly linked to their growth regime, in which the selected deposition conditions are crucial for the final quality of the nanostructure. Moreover, we demonstrate that FEBID and the proposed characterization technique not only allow for growth and chemical analysis of single-element structures, but also offers a new way to directly study 3D core-shell architectures. This straightforward concept could establish a promising route to the design of 3D elements for future nano-electronic devices.

  17. Test Beam Results of 3D Silicon Pixel Sensors for the ATLAS upgrade

    Grenier, P; Barbero, M; Bates, R; Bolle, E; Borri, M; Boscardin, M; Buttar, C; Capua, M; Cavalli-Sforza, M; Cobal, M; Cristofoli, A; Dalla Betta, G F; Darbo, G; Da Via, C; Devetak, E; DeWilde, B; Di Girolamo, B; Dobos, D; Einsweiler, K; Esseni, D; Fazio, S; Fleta, C; Freestone, J; Gallrapp, C; Garcia-Sciveres, M; Gariano, G; Gemme, C; Giordani, M P; Gjersdal, H; Grinstein, S; Hansen, T; Hansen, T E; Hansson, P; Hasi, J; Helle, K; Hoeferkamp, M; Hugging, F; Jackson, P; Jakobs, K; Kalliopuska, J; Karagounis, M; Kenney, C; Köhler, M; Kocian, M; Kok, A; Kolya, S; Korokolov, I; Kostyukhin, V; Krüger, H; La Rosa, A; Lai, C H; Lietaer, N; Lozano, M; Mastroberardino, A; Micelli, A; Nellist, C; Oja, A; Oshea, V; Padilla, C; Palestri, P; Parker, S; Parzefall, U; Pater, J; Pellegrini, G; Pernegger, H; Piemonte, C; Pospisil, S; Povoli, M; Roe, S; Rohne, O; Ronchin, S; Rovani, A; Ruscino, E; Sandaker, H; Seidel, S; Selmi, L; Silverstein, D; Sjøbaek, K; Slavicek, T; Stapnes, S; Stugu, B; Stupak, J; Su, D; Susinno, G; Thompson, R; Tsung, J W; Tsybychev, D; Watts, S J; Wermes, N; Young, C; Zorzi, N

    2011-01-01

    Results on beam tests of 3D silicon pixel sensors aimed at the ATLAS Insertable-B-Layer and High Luminosity LHC (HL-LHC)) upgrades are presented. Measurements include charge collection, tracking efficiency and charge sharing between pixel cells, as a function of track incident angle, and were performed with and without a 1.6 T magnetic field oriented as the ATLAS Inner Detector solenoid field. Sensors were bump bonded to the front-end chip currently used in the ATLAS pixel detector. Full 3D sensors, with electrodes penetrating through the entire wafer thickness and active edge, and double-sided 3D sensors with partially overlapping bias and read-out electrodes were tested and showed comparable performance.

  18. Test beam results of 3D silicon pixel sensors for the ATLAS upgrade

    Grenier, P., E-mail: grenier@slac.stanford.ed [SLAC National Accelerator Laboratory (United States); Alimonti, G. [INFN Sezione di Milano (Italy); Barbero, M. [Bonn University (Germany); Bates, R. [Glasgow University (United Kingdom); Bolle, E. [Oslo University (Norway); Borri, M. [University of Manchester (United Kingdom); Boscardin, M. [FBK-irst, Trento (Italy); Buttar, C. [Glasgow University (United Kingdom); Capua, M. [INFN Gruppo Collegato di Cosenza and Universita della Calabria (Italy); Cavalli-Sforza, M. [IFAE Barcelona (Spain); Cobal, M.; Cristofoli, A. [INFN Gruppo Collegato di Udine and Universita di Udine (Italy); Dalla Betta, G.-F. [INFN Gruppo Collegato di Trento and DISI Universita di Trento (Italy); Darbo, G. [INFN Sezione di Genova (Italy); Da Via, C. [University of Manchester (United Kingdom); Devetak, E.; DeWilde, B. [Stony Brook University (United States); Di Girolamo, B.; Dobos, D. [CERN (Switzerland); Einsweiler, K. [Lawrence Berkeley National Laboratory (United States)

    2011-05-11

    Results on beam tests of 3D silicon pixel sensors aimed at the ATLAS Insertable B-Layer and High Luminosity LHC (HL-LHC) upgrades are presented. Measurements include charge collection, tracking efficiency and charge sharing between pixel cells, as a function of track incident angle, and were performed with and without a 1.6 T magnetic field oriented as the ATLAS inner detector solenoid field. Sensors were bump-bonded to the front-end chip currently used in the ATLAS pixel detector. Full 3D sensors, with electrodes penetrating through the entire wafer thickness and active edge, and double-sided 3D sensors with partially overlapping bias and read-out electrodes were tested and showed comparable performance.

  19. Complex 3D Vortex Lattice Formation by Phase-Engineered Multiple Beam Interference

    Jolly Xavier

    2012-01-01

    Full Text Available We present the computational results on the formation of diverse complex 3D vortex lattices by a designed superposition of multiple plane waves. Special combinations of multiples of three noncoplanar plane waves with a designed relative phase shift between one another are perturbed by a nonsingular beam to generate various complex 3D vortex lattice structures. The formation of complex gyrating lattice structures carrying designed vortices by means of relatively phase-engineered plane waves is also computationally investigated. The generated structures are configured with both periodic as well as transversely quasicrystallographic basis, while these whirling complex lattices possess a long-range order of designed symmetry in a given plane. Various computational analytical tools are used to verify the presence of engineered geometry of vortices in these complex 3D vortex lattices.

  20. Superior performance of cone beam tomography in detecting a calcaneus fracture.

    Lohse, Christian; Catala-Lehnen, Philip; Regier, Marc; Heiland, Max

    2015-01-01

    Cone beam computed tomography is a state-of-the-art imaging tool, initially developed for dental and maxillofacial application. With its high resolution and low radiation dose, cone beam tomography has been expanding its application fields, for example, to diagnosis of traumata and fractures in the head and neck area. In this study, we demonstrate superior and satisfactory performance of cone beam tomography for the imaging of a calcaneus fracture in comparison to conventional X-ray and computed tomography.

  1. Rail Shear and Short Beam Shear Properties of Various 3-Dimensional (3-D) Woven Composites

    2016-01-01

    is unlimited. NOTICES Disclaimers The findings in this report are not to be construed as an official Department of the Army position ... Education , Oak Ridge, TN Chian Yen Weapons and Materials Research Directorate, ARL Approved for public release; distribution is unlimited...TERMS 3-D woven, through-thickness reinforcement , mechanical properties, short beam shear, rail shear, Z-fiber 16. SECURITY CLASSIFICATION OF: 17

  2. SU-E-T-455: Characterization of 3D Printed Materials for Proton Beam Therapy

    Zou, W; Siderits, R; McKenna, M; Khan, A; Yue, N [Rutgers University, New Brunswick, NJ (United States); McDonough, J; Yin, L; Teo, B [University of Pennsylvania, Philadelphia, PA (United States); Fisher, T [Memorial Medical Center, Modesto, CA (United States)

    2014-06-01

    Purpose: The widespread availability of low cost 3D printing technologies provides an alternative fabrication method for customized proton range modifying accessories such as compensators and boluses. However the material properties of the printed object are dependent on the printing technology used. In order to facilitate the application of 3D printing in proton therapy, this study investigated the stopping power of several printed materials using both proton pencil beam measurements and Monte Carlo simulations. Methods: Five 3–4 cm cubes fabricated using three 3D printing technologies (selective laser sintering, fused-deposition modeling and stereolithography) from five printers were investigated. The cubes were scanned on a CT scanner and the depth dose curves for a mono-energetic pencil beam passing through the material were measured using a large parallel plate ion chamber in a water tank. Each cube was measured from two directions (perpendicular and parallel to printing plane) to evaluate the effects of the anisotropic material layout. The results were compared with GEANT4 Monte Carlo simulation using the manufacturer specified material density and chemical composition data. Results: Compared with water, the differences from the range pull back by the printed blocks varied and corresponded well with the material CT Hounsfield unit. The measurement results were in agreement with Monte Carlo simulation. However, depending on the technology, inhomogeneity existed in the printed cubes evidenced from CT images. The effect of such inhomogeneity on the proton beam is to be investigated. Conclusion: Printed blocks by three different 3D printing technologies were characterized for proton beam with measurements and Monte Carlo simulation. The effects of the printing technologies in proton range and stopping power were studied. The derived results can be applied when specific devices are used in proton radiotherapy.

  3. A comprehensive EPID-based 3D validation technique for TrueBeam-delivered VMAT plans

    Ansbacher, W.; Gagne, I. M.; Swift, C.-L.

    2014-03-01

    Purpose: To develop and validate a pre-treatment EPI dosimetry method on Varian TrueBeam linacs using continuous imaging, with reconstruction in a 3D cylindrical phantom geometry. Methods: Delivery of VMAT plans with continuous imaging is currently possible only in Research Mode on TrueBeam linacs, with images acquired in a proprietary format. An earlier technique was adapted to take advantage of technical improvements in EPID delivery, and was tested under various acquisition conditions. The dosimetry of VMAT plans was evaluated at isocentre and within patient volumes that had been transferred to the virtual phantom. Results: Approximately 60 portal image projections per arc were found to be adequate for 3D reconstruction in phantom volumes of 28cm diameter. Twelve prostate, CNS and Head & Neck deliveries were evaluated in Research mode relative to the corresponding Eclipse (v.10) treatment plans, and to measurements on an ArcCheck device in Treatment mode. Mean dose differences at isocentre were within 2% for the three-way comparison, and in PTV volumes were within 1% (s.d. 1%). However, some discrepancies were observed in ArcCheck results that may be related to the small dimensions of certain VMAT apertures. Conclusions: EPI dosimetry with 3D dose reconstruction is an accurate, comprehensive and efficient pre-treatment validation technique for VMAT delivery. Although currently limited to a research mode on TrueBeam, it has the potential to be implemented for clinical use.

  4. Modulation transfer function determination using the edge technique for cone-beam micro-CT

    Rong, Junyan; Liu, Wenlei; Gao, Peng; Liao, Qimei; Lu, Hongbing

    2016-03-01

    Evaluating spatial resolution is an essential work for cone-beam computed tomography (CBCT) manufacturers, prototype designers or equipment users. To investigate the cross-sectional spatial resolution for different transaxial slices with CBCT, the slanted edge technique with a 3D slanted edge phantom are proposed and implemented on a prototype cone-beam micro-CT. Three transaxial slices with different cone angles are under investigation. An over-sampled edge response function (ERF) is firstly generated from the intensity of the slightly tiled air to plastic edge in each row of the transaxial reconstruction image. Then the oversampled ESF is binned and smoothed. The derivative of the binned and smoothed ERF gives the line spread function (LSF). At last the presampled modulation transfer function (MTF) is calculated by taking the modulus of the Fourier transform of the LSF. The spatial resolution is quantified with the spatial frequencies at 10% MTF level and full-width-half-maximum (FWHM) value. The spatial frequencies at 10% of MTFs are 3.1+/-0.08mm-1, 3.0+/-0.05mm-1, and 3.2+/-0.04mm-1 for the three transaxial slices at cone angles of 3.8°, 0°, and -3.8° respectively. The corresponding FWHMs are 252.8μm, 261.7μm and 253.6μm. Results indicate that cross-sectional spatial resolution has no much differences when transaxial slices being 3.8° away from z=0 plane for the prototype conebeam micro-CT.

  5. Incidental findings on cone beam computed tomography: Relate and relay

    Suhas P Pande

    2015-01-01

    Full Text Available Objective: To evaluate the presence of incidental findings on cone beam computed tomography (CBCT images and to recognize their clinical importance. Materials and Methods: A total of 700 CBCT scans between January 2013 to August 2014 at Government Dental College and Hospital were evaluated retrospectively. Results: 459 incidental findings (65.57% were observed in 700 patients. Most common individual incidental finding was mucosal thickening (119 followed by pineal/habenula calcification (99 and choroid plexus (77. Conclusion: The oral and maxillofacial radiologist should carefully interpret all scans and should not ignore the incidental findings and hence avoid untoward snowballing effects.

  6. Diagnostic Applications of Cone-Beam CT for Periodontal Diseases

    AlJehani, Yousef A.

    2014-01-01

    Objectives. This paper aims to review the diagnostic application of cone beam computed tomography (CBCT) in the field of periodontology. Data. Original articles that reported on the use of CBCT for periodontal disease diagnosis were included. Sources. MEDLINE (1990 to January 2014), PubMed (using medical subject headings), and Google Scholar were searched using the following terms in different combinations: “CBCT,” “volumetric CT,” “periodontal disease ,” and “periodontitis.” This was supplem...

  7. Rapidly converging multigrid reconstruction of cone-beam tomographic data

    Myers, Glenn R.; Kingston, Andrew M.; Latham, Shane J.; Recur, Benoit; Li, Thomas; Turner, Michael L.; Beeching, Levi; Sheppard, Adrian P.

    2016-10-01

    In the context of large-angle cone-beam tomography (CBCT), we present a practical iterative reconstruction (IR) scheme designed for rapid convergence as required for large datasets. The robustness of the reconstruction is provided by the "space-filling" source trajectory along which the experimental data is collected. The speed of convergence is achieved by leveraging the highly isotropic nature of this trajectory to design an approximate deconvolution filter that serves as a pre-conditioner in a multi-grid scheme. We demonstrate this IR scheme for CBCT and compare convergence to that of more traditional techniques.

  8. Image analysis and superimposition of 3-dimensional cone-beam computed tomography models

    Cevidanes, Lucia H. S.; Styner, Martin A.; Proffit, William R.

    2013-01-01

    Three-dimensional (3D) imaging techniques can provide valuable information to clinicians and researchers. But as we move from traditional 2-dimensional (2D) cephalometric analysis to new 3D techniques, it is often necessary to compare 2D with 3D data. Cone-beam computed tomography (CBCT) provides simulation tools that can help bridge the gap between image types. CBCT acquisitions can be made to simulate panoramic, lateral, and posteroanterior cephalometric radioagraphs so that they can be compared with preexisting cephalometric databases. Applications of 3D imaging in orthodontics include initial diagnosis and superimpositions for assessing growth, treatment changes, and stability. Three-dimensional CBCT images show dental root inclination and torque, impacted and supernumerary tooth positions, thickness and morphology of bone at sites of mini-implants for anchorage, and osteotomy sites in surgical planning. Findings such as resorption, hyperplasic growth, displacement, shape anomalies of mandibular condyles, and morphological differences between the right and left sides emphasize the diagnostic value of computed tomography acquisitions. Furthermore, relationships of soft tissues and the airway can be assessed in 3 dimensions. PMID:16679201

  9. Metal artifact reduction in cone beam computed tomography using forward projected reconstruction information

    Meilinger, Manuel [Regensburg Univ. (Germany). CIML Group; Siemens Healthcare, Erlangen (Germany); Schmidgunst, Christian; Schuetz, Oliver [Siemens Healthcare, Erlangen (Germany); Lang, Elmar W. [Regensburg Univ. (Germany). CIML Group

    2011-07-01

    In this work we present a new method to reduce artifacts, produced by high-density objects, especially metal implants, in X-ray cone beam computed tomography (CBCT). These artifacts influence clinical diagnostics and treatments using CT data, if metal objects are located in the field of view (FOV). Our novel method reduces metal artifacts by virtually replacing the metal objects with tissue objects of the same shape. First, the considered objects must be segmented in the original 2D projection data as well as in a reconstructed 3D volume. The attenuation coefficients of the segmented voxels are replaced with adequate attenuation coefficients of tissue (or water), then the required parts of the volume are projected onto the segmented 2D pixels, to replace the original information. This corrected 2D data can then be reconstructed with reduced artifacts, i.e. all metal objects virtually vanished. After the reconstruction, the segmented 3D metal objects were re-inserted into the corrected 3D volume. Our method was developed for mobile C-arm CBCTs; as it is necessary that they are of low weight, the C-arm results in unpredictable distortion. This misalignment between the original 2D data and the forward projection of the reconstructed 3D volume must be adjusted before the correction of the segmented 2D pixels. We applied this technique to clinical data and will now present the results. (orig.)

  10. Accuracy of three-dimensional measurements obtained from cone beam computed tomography surface-rendered images for cephalometric analysis: influence of patient scanning position

    Hassan, B.; van der Stelt, P.; Sanderink, G.

    2009-01-01

    The aims of this study were to assess the accuracy of linear measurements on three-dimensional (3D) surface-rendered images generated from cone beam computed tomography (CBCT) in comparison with two-dimensional (2D) slices and 2D lateral and postero-anterior (PA) cephalometric projections, and to in

  11. A comparative evaluation of Cone Beam Computed Tomography (CBCT) and Multi-Slice CT (MSCT) Part I. On subjective image quality

    Liang, X.; Jacobs, R.; Hassan, B.; Li, L.M.; Pauwels, R.; Corpas, L.; Souza, P.C.; Martens, W.; Alonso, A.; Lambrichts, I.

    2010-01-01

    Aims: 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. Materials and methods: One dry mandible was scanned with five CBCT scanners (Accuitomo 3D, i-CAT, NewTom 3G, Galileo

  12. Influence of lead apron shielding on absorbed doses from cone-beam computed tomography.

    Rottke, Dennis; Andersson, Jonas; Ejima, Ken-Ichiro; Sawada, Kunihiko; Schulze, Dirk

    2016-09-24

    The aim of the present work was to investigate absorbed and to calculate effective doses (EDs) in cone-beam computed tomography (CBCT). The study was conducted using examination protocols with and without lead apron shielding. A full-body male RANDO(®) phantom was loaded with 110 GR200A thermoluminescence dosemeter chips at 55 different sites and set up in two different CBCT systems (CS 9500(®), ProMax(®) 3D). Two different protocols were performed: the phantom was set up (1) with and (2) without a lead apron. No statistically significant differences in organ and absorbed doses from regions outside the primary beam could be found when comparing results from exposures with and without lead apron shielding. Consequently, calculating the ED showed no significant differences between the examination protocols with and without lead apron shielding. For the ProMax(®) 3D with shielding, the ED was 149 µSv, and for the examination protocol without shielding 148 µSv (SD = 0.31 µSv). For the CS 9500(®), the ED was 88 and 86 µSv (SD = 0.95 µSv), respectively, with and without lead apron shielding. The results revealed no statistically significant differences in the absorbed doses between examination with and without lead apron shielding, especially in organs outside the primary beam.

  13. Study of negative hydrogen ion beam optics using the 3D3V PIC model

    Miyamoto, K., E-mail: kmiyamot@naruto-u.ac.jp [Naruto University of Education, 748 Nakashima, Takashima, Naruto-cho, Naruto-shi, Tokushima, 772-8502 (Japan); Nishioka, S.; Goto, I.; Hatayama, A. [Faculty of Science and Technology, Keio University, 3-14-1, Hiyoshi, Kohoku-ku, Yokohama, 223-8522 (Japan); Hanada, M.; Kojima, A. [Japan Atomic Energy Agency, 801-1,Mukoyama, Naka, 319-0913 (Japan)

    2015-04-08

    The mechanism of negative ion extraction under real conditions with the complex magnetic field is studied by using the 3D PIC simulation code. The extraction region of the negative ion source for the negative ion based neutral beam injection system in fusion reactors is modelled. It is shown that the E x B drift of electrons is caused by the magnetic filter and the electron suppression magnetic field, and the resultant asymmetry of the plasma meniscus. Furthermore, it is indicated that that the asymmetry of the plasma meniscus results in the asymmetry of negative ion beam profile including the beam halo. It could be demonstrated theoretically that the E x B drift is not significantly weakened by the elastic collisions of the electrons with neutral particles.

  14. 3D Nonlinear Numerical Simulation of Intact and Debonded Reinforced Concrete Beams

    Chen Quan(陈权); Marcus L.

    2004-01-01

    To study the behaviour of reinforced concrete (RC) structures with sections of concrete removed and the reinforcement exposed, 3D nonlinear numerical analysis was performed upon both intact and debonded RC beams by using finite element techniques. The deformational characteristics and the ultimate loads were obtained through numerical models, as well as crack and stress distributions. The failure modes can also be deduced from computational results. Compared with intact beams, the normal assumptions of plane section behaviour is not hold true and the patterns of stress and strain are different in debonded RC beams. The numerical results show good consistency with experimental data. This kind of numerical simulation is a supplement to existing codes.

  15. Ring artifacts removal via spatial sparse representation in cone beam CT

    Li, Zhongyuan; Li, Guang; Sun, Yi; Luo, Shouhua

    2016-03-01

    This paper is about the ring artifacts removal method in cone beam CT. Cone beam CT images often suffer from disturbance of ring artifacts which caused by the non-uniform responses of the elements in detectors. Conventional ring artifacts removal methods focus on the correlation of the elements and the ring artifacts' structural characteristics in either sinogram domain or cross-section image. The challenge in the conventional methods is how to distinguish the artifacts from the intrinsic structures; hence they often give rise to the blurred image results due to over processing. In this paper, we investigate the characteristics of the ring artifacts in spatial space, different from the continuous essence of 3D texture feature of the scanned objects, the ring artifacts are displayed discontinuously in spatial space, specifically along z-axis. Thus we can easily recognize the ring artifacts in spatial space than in cross-section. As a result, we choose dictionary representation for ring artifacts removal due to its high sensitivity to structural information. We verified our theory both in spatial space and coronal-section, the experimental results demonstrate that our methods can remove the artifacts efficiently while maintaining image details.

  16. 3D FE Analysis of RC Beams Externally Strengthened with SRG/SRP Systems

    Francesco Bencardino

    2016-05-01

    Full Text Available The purpose of this study is to evaluate, through a nonlinear Finite Element (FE analysis, the structural behavior of Reinforced Concrete (RC beams externally strengthened by using Steel Reinforced Grout (SRG and Steel Reinforced Polymer (SRP systems. The parameters taken into account were the external strengthening configuration, with or without U-wrap end anchorages, as well as the strengthening materials. The numerical simulations were carried out by using a three-dimensional (3D FE model. The linear and nonlinear behavior of all materials was modeled by appropriate constitutive laws and the connection between concrete substrate and external reinforcing layer was simulated by means of cohesive surfaces with appropriate bond-slip laws. In order to overcome convergence difficulties, to simulate the quasi-static response of the strengthened RC beams, a dynamic approach was adopted. The numerical results in terms of load-displacement curves, failure modes, and load and strain values at critical stages were validated against some experimental data. As a result, the proposed 3D FE model can be used to predict the structural behavior up to ultimate stage of similar strengthened beams without carrying out experimental tests.

  17. Dynamic cone beam CT angiography of carotid and cerebral arteries using canine model

    Cai, Weixing; zhao,binghui; Conover, David; Liu, Jiangkun; Ning, Ruola

    2012-01-01

    Purpose: This research is designed to develop and evaluate a flat-panel detector-based dynamic cone beam CT system for dynamic angiography imaging, which is able to provide both dynamic functional information and dynamic anatomic information from one multirevolution cone beam CT scan.

  18. Reduction of beam hardening artifacts in cone-beam CT imaging via SMART-RECON algorithm

    Li, Yinsheng; Garrett, John; Chen, Guang-Hong

    2016-03-01

    When an automatic exposure control is introduced in C-arm cone beam CT data acquisition, the spectral inconsistencies between acquired projection data are exacerbated. As a result, conventional water/bone correction schemes are not as effective as in conventional diagnostic x-ray CT acquisitions with a fixed tube potential. In this paper, a new method was proposed to reconstruct several images with different degrees of spectral consistency and thus different levels of beam hardening artifacts. The new method relies neither on prior knowledge of the x-ray beam spectrum nor on prior compositional information of the imaging object. Numerical simulations were used to validate the algorithm.

  19. Reconstruction-plane-dependent weighted FDK algorithm for cone beam volumetric CT

    Tang, Xiangyang; Hsieh, Jiang

    2005-04-01

    The original FDK algorithm has been extensively employed in medical and industrial imaging applications. With an increased cone angle, cone beam (CB) artifacts in images reconstructed by the original FDK algorithm deteriorate, since the circular trajectory does not satisfy the so-called data sufficiency condition (DSC). A few "circular plus" trajectories have been proposed in the past to reduce CB artifacts by meeting the DSC. However, the circular trajectory has distinct advantages over other scanning trajectories in practical CT imaging, such as cardiac, vascular and perfusion applications. In addition to looking into the DSC, another insight into the CB artifacts of the original FDK algorithm is the inconsistency between conjugate rays that are 180° apart in view angle. The inconsistence between conjugate rays is pixel dependent, i.e., it varies dramatically over pixels within the image plane to be reconstructed. However, the original FDK algorithm treats all conjugate rays equally, resulting in CB artifacts that can be avoided if appropriate view weighting strategy is exercised. In this paper, a modified FDK algorithm is proposed, along with an experimental evaluation and verification, in which the helical body phantom and a humanoid head phantom scanned by a volumetric CT (64 x 0.625 mm) are utilized. Without extra trajectories supplemental to the circular trajectory, the modified FDK algorithm applies reconstruction-plane-dependent view weighting on projection data before 3D backprojection, which reduces the inconsistency between conjugate rays by suppressing the contribution of one of the conjugate rays with a larger cone angle. Both computer-simulated and real phantom studies show that, up to a moderate cone angle, the CB artifacts can be substantially suppressed by the modified FDK algorithm, while advantages of the original FDK algorithm, such as the filtered backprojection algorithm structure, 1D ramp filtering, and data manipulation efficiency, can be

  20. Design and application of 3D-printed stepless beam modulators in proton therapy

    Lindsay, C.; Kumlin, J.; Martinez, D. M.; Jirasek, A.; Hoehr, C.

    2016-06-01

    A new method for the design of stepless beam modulators for proton therapy is described and verified. Simulations of the classic designs are compared against the stepless method for various modulation widths which are clinically applicable in proton eye therapy. Three modulator wheels were printed using a Stratasys Objet30 3D printer. The resulting depth dose distributions showed improved uniformity over the classic stepped designs. Simulated results imply a possible improvement in distal penumbra width; however, more accurate measurements are needed to fully verify this effect. Lastly, simulations were done to model bio-equivalence to Co-60 cell kill. A wheel was successfully designed to flatten this metric.

  1. General beam cross-section analysis using a 3D finite element slice

    Couturier, Philippe; Krenk, Steen

    2014-01-01

    A formulation for analysis of general cross-section properties has been developed. This formulation is based on the stress-strain states in the classic six equilibrium modes of a beam by considering a finite thickness slice modelled by a single layer of 3D finite elements. The displacement...... an analytical solution is available. The paper also shows an application to wind turbine blade cross-sections and discusses the effect of the finite element discretization on the cross-section properties such as stiffness parameters and the location of the elastic and shear centers....

  2. Role of C-arm cone-beam CT in chemoembolization for hepatocellular carcinoma

    Kim, Hyo Cheol [Dept. of Radiology, Seoul National University College of Medicine, Institute of Radiation Medicine, Seoul (Korea, Republic of)

    2015-02-15

    With the advent of C-arm cone-beam computed tomography (CBCT), minimally-invasive procedures in the angiography suite made a new leap beyond the limitations of 2-dimensional (D) angiography alone. C-arm CBCT can help interventional radiologists in several ways with the treatment of hepatocellular carcinoma (HCC); visualization of small tumors and tumor-feeding arteries, identification of occult lesion and 3D configuration of tortuous hepatic arteries, assurance of completeness of chemoembolization, suggestion of presence of extrahepatic collateral arteries supplying HCCs, and prevention of nontarget embolization. With more improvements in the technology, C-arm CBCT may be essential in all kinds of interventional procedures in the near future.

  3. Current status of dental caries diagnosis using cone beam computed tomography

    Park, Young Seok; Ahn, Jin Soo; Kwon, Ho Beom; Lee, Seung Pyo [School of Dentistry, Seoul National University, Seoul (Korea, Republic of)

    2011-06-15

    The purpose of this article is to review the current status of dental caries diagnosis using cone beam computed tomography (CBCT). An online PubMed search was performed to identify studies on caries research using CBCT. Despite its usefulness, there were inherent limitations in the detection of caries lesions through conventional radiograph mainly due to the two-dimensional (2D) representation of caries lesions. Several efforts were made to investigate the three-dimensional (3D) image of lesion, only to gain little popularity. Recently, CBCT was introduced and has been used for diagnosis of caries in several reports. Some of them maintained the superiority of CBCT systems, however it is still under controversies. The CBCT systems are promising, however they should not be considered as a primary choice of caries diagnosis in everyday practice yet. Further studies under more standardized condition should be performed in the near future.

  4. Experience of direct percutaneous sac injection in type II endoleak using cone beam computed tomography.

    Park, Yoong-Seok; Do, Young Soo; Park, Hong Suk; Park, Kwang Bo; Kim, Dong-Ik

    2015-04-01

    Cone beam CT, usually used in dental area, could easily obtain 3-dimensional images using cone beam shaped ionized radiation. Cone beam CT is very useful for direct percutaneous sac injection (DPSI) which needs very precise measurement to avoid puncture of inferior vena cava or vessel around sac or stent graft. Here we describe two cases of DPSI using cone beam CT. In case 1, a 79-year-old male had widening of preexisted type II endoleak after endovascular aneurysm repair (EVAR). However, transarterial embolization failed due to tortuous collateral branches of lumbar arteries. In case 2, a 72-year-old female had symptomatic sac enlargement by type II endoleak after EVAR. However, there was no route to approach the lumbar arteries. Therefore, we performed DPSI assisted by cone beam CT in cases 1, 2. Six-month CT follow-up revealed no sign of sac enlargement by type II endoleak.

  5. WE-F-16A-05: Use of 3D-Printers to Create a Tissue Equivalent 3D-Bolus for External Beam Therapy

    Burleson, S; Baker, J; Hsia, A; Xu, Z [Stony Brook Medicine, Stony Brook, NY (United States)

    2014-06-15

    Purpose: The purpose of this project is to demonstrate that a non-expensive 3D-printer can be used to manufacture a 3D-bolus for external beam therapy. The printed bolus then can be modeled in our treatment planning system to ensure accurate dose delivery to the patient. Methods: We developed a simple method to manufacture a patient-specific custom 3Dbolus. The bolus is designed using Eclipse Treatment Planning System, contoured onto the patients CT images. The bolus file is exported from Eclipse to 3D-printer software, and then printed using a 3D printer. Various tests were completed to determine the properties of the printing material. Percent depth dose curves in this material were measured with electron and photon beams for comparison to other materials. In order to test the validity of the 3D printed bolus for treatment planning, a custom bolus was printed and tested on the Rando phantom using film for a dose plane comparison. We compared the dose plane measured on the film to the same dose plane exported from our treatment planning system using Film QA software. The gamma-dose distribution tool was used in our film analysis. Results: We compared point measurements throughout the dose plane and were able to achieve greater than 95% passing rate at 3% dose difference and 3 mm distance to agreement, which is our departments acceptable gamma pixel parameters. Conclusion: The printed 3D bolus has proven to be accurately modeled in our treatment planning system, it is more conformal to the patient surface and more durable than other bolus currently used (wax, superflab etc.). It is also more convenient and less costly than comparable bolus from milling machine companies.

  6. Cone beam computed tomography of plastinated hearts for instruction of radiological anatomy.

    Chang, Chih-Wei; Atkinson, Gregory; Gandhi, Niket; Farrell, Michael L; Labrash, Steven; Smith, Alice B; Norton, Neil S; Matsui, Takashi; Lozanoff, Scott

    2016-09-01

    Radiological anatomy education is an important aspect of the medical curriculum. The purpose of this study was to establish and demonstrate the use of plastinated anatomical specimens, specifically human hearts, for use in radiological anatomy education. Four human hearts were processed with routine plastination procedures at room temperature. Specimens were subjected to cone beam computed tomography and a graphics program (ER3D) was applied to generate 3D cardiac models. A comparison was conducted between plastinated hearts and their corresponding computer models based on a list of morphological cardiac features commonly studied in the gross anatomy laboratory. Results showed significant correspondence between plastinations and CBCT-generated 3D models (98 %; p correspondence was achieved between plastinations and 2D CBCT slices. Complete correspondence (100 %) was achieved between key observations on the plastinations and internal radiological findings typically required of medical student. All pathologic features seen on the plastinated hearts were also visualized internally with the CBCT-generated models and 2D slices. These results suggest that CBCT-derived slices and models can be successfully generated from plastinated material and provide accurate representations for radiological anatomy education.

  7. Effect of anatomical backgrounds on detectability in volumetric cone beam CT images

    Han, Minah; Park, Subok; Baek, Jongduk

    2016-03-01

    As anatomical noise is often a dominating factor affecting signal detection in medical imaging, we investigate the effects of anatomical backgrounds on signal detection in volumetric cone beam CT images. Signal detection performances are compared between transverse and longitudinal planes with either uniform or anatomical backgrounds. Sphere objects with diameters of 1mm, 5mm, 8mm, and 11mm are used as the signals. Three-dimensional (3D) anatomical backgrounds are generated using an anatomical noise power spectrum, 1/fβ, with β=3, equivalent to mammographic background [1]. The mean voxel value of the 3D anatomical backgrounds is used as an attenuation coefficient of the uniform background. Noisy projection data are acquired by the forward projection of the uniform and anatomical 3D backgrounds with/without sphere lesions and by the addition of quantum noise. Then, images are reconstructed by an FDK algorithm [2]. For each signal size, signal detection performances in transverse and longitudinal planes are measured by calculating the task SNR of a channelized Hotelling observer with Laguerre-Gauss channels. In the uniform background case, transverse planes yield higher task SNR values for all sphere diameters but 1mm. In the anatomical background case, longitudinal planes yield higher task SNR values for all signal diameters. The results indicate that it is beneficial to use longitudinal planes to detect spherical signals in anatomical backgrounds.

  8. Region-of-interest cone beam computed tomography (ROI CBCT) with a high resolution CMOS detector

    Jain, A.; Takemoto, H.; Silver, M. D.; Nagesh, S. V. S.; Ionita, C. N.; Bednarek, D. R.; Rudin, S.

    2015-03-01

    Cone beam computed tomography (CBCT) systems with rotational gantries that have standard flat panel detectors (FPD) are widely used for the 3D rendering of vascular structures using Feldkamp cone beam reconstruction algorithms. One of the inherent limitations of these systems is limited resolution (<3 lp/mm). There are systems available with higher resolution but their small FOV limits them to small animal imaging only. In this work, we report on region-of-interest (ROI) CBCT with a high resolution CMOS detector (75 μm pixels, 600 μm HR-CsI) mounted with motorized detector changer on a commercial FPD-based C-arm angiography gantry (194 μm pixels, 600 μm HL-CsI). A cylindrical CT phantom and neuro stents were imaged with both detectors. For each detector a total of 209 images were acquired in a rotational protocol. The technique parameters chosen for the FPD by the imaging system were used for the CMOS detector. The anti-scatter grid was removed and the incident scatter was kept the same for both detectors with identical collimator settings. The FPD images were reconstructed for the 10 cm x10 cm FOV and the CMOS images were reconstructed for a 3.84 cm x 3.84 cm FOV. Although the reconstructed images from the CMOS detector demonstrated comparable contrast to the FPD images, the reconstructed 3D images of the neuro stent clearly showed that the CMOS detector improved delineation of smaller objects such as the stent struts (~70 μm) compared to the FPD. Further development and the potential for substantial clinical impact are suggested.

  9. Three-dimensional cone-beam computed tomography for assessment of mandibular changes after orthognathic surgery

    Cevidanes, Lucia H. S.; Bailey, L'Tanya J.; Tucker, Scott F.; Styner, Martin A.; Mol, Andre; Phillips, Ceib L.; Proffit, William R.; Turvey, Timothy

    2013-01-01

    Introduction The purpose of this study was to assess alterations in the 3-dimensional (3D) position of the mandibular rami and condyles in patients receiving either maxillary advancement and mandibular setback or maxillary surgery only. Methods High-resolution cone-beam computed tomography scans were taken of 21 patients before and after orthognathic surgery. Ten patients with various malocclusions underwent maxillary surgery only, and 11 Class III patients received maxillary advancement and mandibular setback. Presurgery and postsurgery 3D models were registered on the surface of the cranial base. A new tool was used for graphical overlay and 3D display with color maps to visually assess the locations and to quantify positional changes in the posterior border of the mandibular rami and condyles between superimposed models. Results The average displacements in condylar position were small—0.77 mm (SD, 0.12 mm) and 0.70 mm (SD, 0.08 mm)—for 2-jaw and 1-jaw surgeries, respectively (not significant, P >.05). All 2-jaw surgery patients had backward rotational displacements of the mandibular rami (mean, 1.98 mm; SD, 1.03 mm), with a maximum surface distance change of ≥2 mm in 8 of 11 subjects. For the 1-jaw surgery, all subjects had small backward rotational displacements of the mandibular rami (mean, 0.78 mm; SD, 0.25 mm), with only 1 subject having a maximum surface distance change ≥2 mm. The difference in mean backward rotational displacement was statistically significant (P <.01). Conclusions The visualization of 3D model superimposition clearly identified the location, magnitude, and direction of mandibular displacement. The 3D imaging allowed quantification of vertical, transverse, and anteroposterior ramus displacement that accompanied mandibular, but not maxillary only, surgery. PMID:17208105

  10. Enhancement of mobile C-arm cone-beam reconstruction using prior anatomical models

    Sadowsky, Ofri; Lee, Junghoon; Sutter, Edward G.; Wall, Simon J.; Prince, Jerry L.; Taylor, Russell H.

    2009-02-01

    We demonstrate an improvement to cone-beam tomographic imaging by using a prior anatomical model. A protocol for scanning and reconstruction has been designed and implemented for a conventional mobile C-arm: a 9 inch image-intensifier OEC-9600. Due to the narrow field of view (FOV), the reconstructed image contains strong truncation artifacts. We propose to improve the reconstructed images by fusing the observed x-ray data with computed projections of a prior 3D anatomical model, derived from a subject-specific CT or from a statistical database (atlas), and co-registered (3D/2D) to the x-rays. The prior model contains a description of geometry and radiodensity as a tetrahedral mesh shape and density polynomials, respectively. A CT-based model can be created by segmentation, meshing and polynomial fitting of the object's CT study. The statistical atlas is created through principal component analysis (PCA) of a collection of mesh instances deformably-registered (3D/3D) to patient datasets. The 3D/2D registration method optimizes a pixel-based similarity score (mutual information) between the observed x-rays and the prior. The transformation involves translation, rotation and shape deformation based on the atlas. After registration, the image intensities of observed and prior projections are matched and adjusted, and the two information sources are blended as inputs to a reconstruction algorithm. We demonstrate recostruction results of three cadaveric specimens, and the effect of fusing prior data to compensate for truncation. Further uses of hybrid reconstruction, such as compensation for the scan's limited arc length, are suggested for future research.

  11. Implementation of a fully 3D system model for brain SPECT with fan- beam-collimator OSEM reconstruction with 3D total variation regularization

    Ye, Hongwei; Krol, Andrzej; Lipson, Edward D.; Lu, Yao; Xu, Yuesheng; Lee, Wei; Feiglin, David H.

    2007-03-01

    In order to improve tomographically reconstructed image quality, we have implemented a fully 3D reconstruction, using an ordered subsets expectation maximization (OSEM) algorithm for fan-beam collimator (FBC) SPECT, along with a volumetric system model-fan-volume system model (FVSM), a modified attenuation compensation, a 3D depth- and angle-dependent resolution and sensitivity correction, and a 3D total variation (TV) regularization. SPECT data were acquired in a 128x64 matrix, in 120 views with a circular orbit. The numerical Zubal brain phantom was used to simulate a FBC HMPAO Tc-99m brain SPECT scan, and a low noise and scatter-free projection dataset was obtained using the SimSET Monte Carlo package. A SPECT scan for a mini-Defrise phantom and brain HMPAO SPECT scans for five patients were acquired with a triple-head gamma camera (Triad 88) equipped with a low-energy high-resolution (LEHR) FBC. The reconstructed images, obtained using clinical filtered back projection (FBP), OSEM with a line-length system model (LLSM) and 3D TV regularization, and OSEM with FVSM and 3D TV regularization were quantitatively studied. Overall improvement in the image quality has been observed, including better axial and transaxial resolution, better integral uniformity, higher contrast-to-noise ration between the gray matter and the white matter, and better accuracy and lower bias in OSEM-FVSM, compared with OSEM-LLSM and clinical FBP.

  12. Extracting respiratory signals from thoracic cone beam CT projections

    Yan, Hao; Yin, Wotao; Pan, Tinsu; Ahmad, Moiz; Mou, Xuanqin; Cervino, Laura; Jia, Xun; Jiang, Steve B

    2012-01-01

    Patient respiratory signal associated with the cone beam CT (CBCT) projections is important for lung cancer radiotherapy. In contrast to monitoring an external surrogate of respiration, such signal can be extracted directly from the CBCT projections. In this paper, we propose a novel local principle component analysis (LPCA) method to extract the respiratory signal by distinguishing the respiration motion-induced content change from the gantry rotation-induced content change in the CBCT projections. The LPCA method is evaluated by comparing with three state-of-the-art projection-based methods, namely, the Amsterdam Shroud (AS) method, the intensity analysis (IA) method, and the Fourier-transform based phase analysis (FT-p) method. The clinical CBCT projection data of eight patients, acquired under various clinical scenarios, were used to investigate the performance of each method. We found that the proposed LPCA method has demonstrated the best overall performance for cases tested and thus is a promising tech...

  13. Comparing cone beam laminographic system trajectories for composite NDT

    Neil O'Brien

    2016-11-01

    Full Text Available We compare the quality of reconstruction obtainable using various laminographic system trajectories that have been described in the literature, with reference to detecting defects in composite materials in engineering. We start by describing a laminar phantom representing a simplified model of composite panel, which models certain defects that may arise in such materials, such as voids, resin rich areas, and delamination, and additionally features both blind and through holes along multiple axes. We simulate ideal cone-beam projections of this phantom with the different laminographic trajectories, applying both Simultaneous Iterative Reconstruction Technique (SIRT and Conjugate Gradient Least Squares (CGLS reconstruction algorithms. We compare the quality of the reconstructions with a view towards optimising the scan parameters for defect detectability in composite NDT applications.

  14. Diagnostic Applications of Cone-Beam CT for Periodontal Diseases

    Yousef A. AlJehani

    2014-01-01

    Full Text Available Objectives. This paper aims to review the diagnostic application of cone beam computed tomography (CBCT in the field of periodontology. Data. Original articles that reported on the use of CBCT for periodontal disease diagnosis were included. Sources. MEDLINE (1990 to January 2014, PubMed (using medical subject headings, and Google Scholar were searched using the following terms in different combinations: “CBCT,” “volumetric CT,” “periodontal disease ,” and “periodontitis.” This was supplemented by hand-searching in peer-reviewed journals and cross-referenced with the articles accessed. Conclusions. Bony defects, caters, and furcation involvements seem to be better depicted on CBCT, whereas bone quality and periodontal ligament space scored better on conventional intraoral radiography. CBCT does not offer a significant advantage over conventional radiography for assessing the periodontal bone levels.

  15. Dose calculation based on Cone Beam CT images

    Slot Thing, Rune

    , several other factors contributing to the image quality degradation, and while one should, theoretically, be able to obtain CT-like image quality from CBCT scans, clinical image quality is often very far from this ideal realisation. The present thesis describes the investigation of potential image quality...... improvements in clinical CBCT imaging achieved through post-processing of the clinical image data. A Monte Carlo model was established to predict patient specific scattered radiation in CBCT imaging, based on anatomical information from the planning CT scan. This allowed the time consuming Monte Carlo......Cone beam CT (CBCT) imaging is frequently used in modern radiotherapy to ensure the proper positioning of the patient prior to each treatment fraction. With the increasing use of CBCT imaging for image guidance, interest has grown in exploring the potential use of these 3– or 4–D medical images...

  16. Fossa navicularis magna detection on cone-beam computed tomography

    Syed, Ali Z. [Dept. of Oral and Maxillofacial Medicine and Diagnostic Sciences, School of Dental Medicine, Case Western Reserve University, Cleveland(United States); Mupparapu, Mel [Div. of Radiology, University of Pennsylvania School of Dental Medicine, Philadelphia (United States)

    2016-03-15

    Herein, we report and discuss the detection of fossa navicularis magna, a close radiographic anatomic variant of canalis basilaris medianus of the basiocciput, as an incidental finding in cone-beam computed tomography (CBCT) imaging. The CBCT data of the patients in question were referred for the evaluation of implant sites and to rule out pathology in the maxilla and mandible. CBCT analysis showed osseous, notch-like defects on the inferior aspect of the clivus in all four cases. The appearance of fossa navicularis magna varied among the cases. In some, it was completely within the basiocciput and mimicked a small rounded, corticated, lytic defect, whereas it appeared as a notch in others. Fossa navicularis magna is an anatomical variant that occurs on the inferior aspect of the clivus. The pertinent literature on the anatomical variations occurring in this region was reviewed.

  17. 3D-FBK Pixel sensors: recent beam tests results with irradiated devices

    Micelli, A; Sandaker, H; Stugu, B; Barbero, M; Hugging, F; Karagounis, M; Kostyukhin, V; Kruger, H; Tsung, J W; Wermes, N; Capua, M; Fazio, S; Mastroberardino, A; Susinno, G; Gallrapp, C; Di Girolamo, B; Dobos, D; La Rosa, A; Pernegger, H; Roe, S; Slavicek, T; Pospisil, S; Jakobs, K; Kohler, M; Parzefall, U; Darbo, G; Gariano, G; Gemme, C; Rovani, A; Ruscino, E; Butter, C; Bates, R; Oshea, V; Parker, S; Cavalli-Sforza, M; Grinstein, S; Korokolov, I; Pradilla, C; Einsweiler, K; Garcia-Sciveres, M; Borri, M; Da Via, C; Freestone, J; Kolya, S; Lai, C H; Nellist, C; Pater, J; Thompson, R; Watts, S J; Hoeferkamp, M; Seidel, S; Bolle, E; Gjersdal, H; Sjobaek, K N; Stapnes, S; Rohne, O; Su, D; Young, C; Hansson, P; Grenier, P; Hasi, J; Kenney, C; Kocian, M; Jackson, P; Silverstein, D; Davetak, H; DeWilde, B; Tsybychev, D; Dalla Betta, G F; Gabos, P; Povoli, M; Cobal, M; Giordani, M P; Selmi, L; Cristofoli, A; Esseni, D; Palestri, P; Fleta, C; Lozano, M; Pellegrini, G; Boscardin, M; Bagolini, A; Piemonte, C; Ronchin, S; Zorzi, N; Hansen, T E; Hansen, T; Kok, A; Lietaer, N; Kalliopuska, J; Oja, A

    2011-01-01

    The Pixel detector is the innermost part of the ATLAS experiment tracking device at the Large Hadron Collider (LHC), and plays a key role in the reconstruction of the primary and secondary vertices of short-lived particles. To cope with the high level of radiation produced during the collider operation, it is planned to add to the present three layers of silicon pixel sensors which constitute the Pixel Detector, an additional layer (Insertable B-Layer, or IBL) of sensors. 3D silicon sensors are one of the technologies which are under study for the IBL. 3D silicon technology is an innovative combination of very-large-scale integration (VLSI) and Micro-Electro-Mechanical-Systems (MEMS) where electrodes are fabricated inside the silicon bulk instead of being implanted on the wafer surfaces. 3D sensors, with electrodes fully or partially penetrating the silicon substrate, are currently fabricated at different processing facilities in Europe and USA. This paper reports on the 2010 June beam test results for irradi...

  18. 3D Medipix2 detector characterization with a micro-focused X-ray beam

    Gimenez, E. N.; Maneuski, D.; Mac Raighne, A.; Parkes, C.; Bates, R.; O'Shea, V.; Fleta, C.; Pellegrini, G.; Lozano, M.; Alianelli, L.; Sawhney, K. J. S.; Marchal, J.; Tartoni, N.

    2011-05-01

    Three-dimensional (3D) photodiode detectors offer advantages over standard planar photodiodes in a wide range of applications. The main advantage of these sensors for X-ray imaging is their reduced charge sharing between adjacent pixels, which could improve spatial and spectral resolution. However, a drawback of 3D sensors structures is the loss of detection efficiency due to the presence in the pixel structure of heavily doped electrode columns which are insensitive to X-ray. In this work two types of 3D silicon detectors: n-type wafer with hole collecting readout-columns (N-TYPE) and p-type wafer with electron collecting readout-columns (P-TYPE), bump-bounded to a Medipix2 read-out chip were characterized with a 14.5 keV micro-focused X-ray beam from a synchrotron. Measurements of the detection efficiency and the charge sharing were performed at different bias voltages and Medipix2 energy thresholds and compared with those of a standard planar silicon sensor.

  19. Iodine contrast cone beam CT imaging of breast cancer

    Partain, Larry; Prionas, Stavros; Seppi, Edward; Virshup, Gary; Roos, Gerhard; Sutherland, Robert; Boone, John

    2007-03-01

    An iodine contrast agent, in conjunction with an X-ray cone beam CT imaging system, was used to clearly image three, biopsy verified, cancer lesions in two patients. The lesions were approximately in the 10 mm to 6 mm diameter range. Additional regions were also enhanced with approximate dimensions down to 1 mm or less in diameter. A flat panel detector, with 194 μm pixels in 2 x 2 binning mode, was used to obtain 500 projection images at 30 fps with an 80 kVp X-ray system operating at 112 mAs, for an 8-9 mGy dose - equivalent to two view mammography for these women. The patients were positioned prone, while the gantry rotated in the horizontal plane around the uncompressed, pendant breasts. This gantry rotated 360 degrees during the patient's 16.6 sec breath hold. A volume of 100 cc of 320 mg/ml iodine-contrast was power injected at 4 cc/sec, via catheter into the arm vein of the patient. The resulting 512 x 512 x 300 cone beam CT data set of Feldkamp reconstructed ~(0.3 mm) 3 voxels were analyzed. An interval of voxel contrast values, characteristic of the regions with iodine contrast enhancement, were used with surface rendering to clearly identify up to a total of 13 highlighted volumes. This included the three largest lesions, that were previously biopsied and confirmed to be malignant. The other ten highlighted regions, of smaller diameters, are likely areas of increased contrast trapping unrelated to cancer angiogenesis. However the technique itself is capable of resolving lesions that small.

  20. 3D beam shape estimation based on distributed coaxial cable interferometric sensor

    Cheng, Baokai; Zhu, Wenge; Liu, Jie; Yuan, Lei; Xiao, Hai

    2017-03-01

    We present a coaxial cable interferometer based distributed sensing system for 3D beam shape estimation. By making a series of reflectors on a coaxial cable, multiple Fabry–Perot cavities are created on it. Two cables are mounted on the beam at proper locations, and a vector network analyzer (VNA) is connected to them to obtain the complex reflection signal, which is used to calculate the strain distribution of the beam in horizontal and vertical planes. With 6 GHz swept bandwidth on the VNA, the spatial resolution for distributed strain measurement is 0.1 m, and the sensitivity is 3.768 MHz mε ‑1 at the interferogram dip near 3.3 GHz. Using displacement-strain transformation, the shape of the beam is reconstructed. With only two modified cables and a VNA, this system is easy to implement and manage. Comparing to optical fiber based sensor systems, the coaxial cable sensors have the advantage of large strain and robustness, making this system suitable for structure health monitoring applications.

  1. Parametric instabilities in 3D periodically focused beams with space charge

    Hofmann, Ingo; Boine-Frankenheim, Oliver

    2017-01-01

    Parametric resonances of beam eigenmodes with a periodic focusing system under the effect of space charge—also called structural instabilities—are the collective counterparts to parametric resonances of single particles or of mechanical systems. Their common feature is that an exponential instability is driven by a temporal modulation of a system parameter. Thus, they are complementary to the more commonly considered space charge single particle resonances, where space charge pseudo-multipole terms are assumed to exist already at finite level in the initial distribution. This article elaborates on the characteristics of such parametric instabilities in 3D bunched beams—as typical in linear accelerators—for modes of second (envelope), third and fourth order, including the transverse coupled "sum envelope instabilities" recently discovered for 2D beams. Noteworthy results are the finding that parametric resonances can be in competition with single particle resonances of twice the order due to overlapping stopbands; furthermore the surprisingly good applicability of the stopband positions and widths obtained from previously published 2D linearised Vlasov stability theory to the 3D non-Kapchinskij-Vladimirskij particle-in-cell code studies presented here.

  2. Design of a Compton camera for 3D prompt-{gamma} imaging during ion beam therapy

    Roellinghoff, F., E-mail: roelling@ipnl.in2p3.fr [Universite de Lyon, F-69622 Lyon (France); Universite Lyon 1 and CNRS/IN2P3, UMR 5822, IPNL, F-69622 Villeurbanne (France); INSA-Lyon Laboratory of Nondestructive Testing using Ionizing Radiation (CNDRI), F-69621 Villeurbanne Cedex (France); Richard, M.-H., E-mail: mrichard@ipnl.in2p3.fr [Universite de Lyon, F-69622 Lyon (France); Universite Lyon 1 and CNRS/IN2P3, UMR 5822, IPNL, F-69622 Villeurbanne (France); INSA-Lyon Laboratory of Nondestructive Testing using Ionizing Radiation (CNDRI), F-69621 Villeurbanne Cedex (France); Chevallier, M.; Constanzo, J.; Dauvergne, D. [Universite de Lyon, F-69622 Lyon (France); Universite Lyon 1 and CNRS/IN2P3, UMR 5822, IPNL, F-69622 Villeurbanne (France); Freud, N. [INSA-Lyon Laboratory of Nondestructive Testing using Ionizing Radiation (CNDRI), F-69621 Villeurbanne Cedex (France); Henriquet, P.; Le Foulher, F. [Universite de Lyon, F-69622 Lyon (France); Universite Lyon 1 and CNRS/IN2P3, UMR 5822, IPNL, F-69622 Villeurbanne (France); Letang, J.M. [INSA-Lyon Laboratory of Nondestructive Testing using Ionizing Radiation (CNDRI), F-69621 Villeurbanne Cedex (France); Montarou, G. [LPC, CNRS/IN2P3, Clermont-F. University (France); Ray, C.; Testa, E.; Testa, M. [Universite de Lyon, F-69622 Lyon (France); Universite Lyon 1 and CNRS/IN2P3, UMR 5822, IPNL, F-69622 Villeurbanne (France); Walenta, A.H. [Uni-Siegen, FB Physik, Emmy-Noether Campus, D-57068 Siegen (Germany)

    2011-08-21

    We investigate, by means of Geant4 simulations, a real-time method to control the position of the Bragg peak during ion therapy, based on a Compton camera in combination with a beam tagging device (hodoscope) in order to detect the prompt gamma emitted during nuclear fragmentation. The proposed set-up consists of a stack of 2 mm thick silicon strip detectors and a LYSO absorber detector. The {gamma} emission points are reconstructed analytically by intersecting the ion trajectories given by the beam hodoscope and the Compton cones given by the camera. The camera response to a polychromatic point source in air is analyzed with regard to both spatial resolution and detection efficiency. Various geometrical configurations of the camera have been tested. In the proposed configuration, for a typical polychromatic photon point source, the spatial resolution of the camera is about 8.3 mm FWHM and the detection efficiency 2.5x10{sup -4} (reconstructable photons/emitted photons in 4{pi}). Finally, the clinical applicability of our system is considered and possible starting points for further developments of a prototype are discussed.

  3. Experimental pencil beam kernels derivation for 3D dose calculation in flattening filter free modulated fields

    Diego Azcona, Juan; Barbés, Benigno; Wang, Lilie; Burguete, Javier

    2016-01-01

    This paper presents a method to obtain the pencil-beam kernels that characterize a megavoltage photon beam generated in a flattening filter free (FFF) linear accelerator (linac) by deconvolution from experimental measurements at different depths. The formalism is applied to perform independent dose calculations in modulated fields. In our previous work a formalism was developed for ideal flat fluences exiting the linac’s head. That framework could not deal with spatially varying energy fluences, so any deviation from the ideal flat fluence was treated as a perturbation. The present work addresses the necessity of implementing an exact analysis where any spatially varying fluence can be used such as those encountered in FFF beams. A major improvement introduced here is to handle the actual fluence in the deconvolution procedure. We studied the uncertainties associated to the kernel derivation with this method. Several Kodak EDR2 radiographic films were irradiated with a 10 MV FFF photon beam from two linacs from different vendors, at the depths of 5, 10, 15, and 20cm in polystyrene (RW3 water-equivalent phantom, PTW Freiburg, Germany). The irradiation field was a 50mm diameter circular field, collimated with a lead block. The 3D kernel for a FFF beam was obtained by deconvolution using the Hankel transform. A correction on the low dose part of the kernel was performed to reproduce accurately the experimental output factors. Error uncertainty in the kernel derivation procedure was estimated to be within 0.2%. Eighteen modulated fields used clinically in different treatment localizations were irradiated at four measurement depths (total of fifty-four film measurements). Comparison through the gamma-index to their corresponding calculated absolute dose distributions showed a number of passing points (3%, 3mm) mostly above 99%. This new procedure is more reliable and robust than the previous one. Its ability to perform accurate independent dose calculations was

  4. 3D micro-optical elements for generation of tightly focused vortex beams

    Balčytis Armandas

    2015-01-01

    Full Text Available Orbital angular momentum carrying light beams are usedfor optical trapping and manipulation. This emerging trend provides new challenges involving device miniaturization for improved performance and enhanced functionality at the microscale. Here we discus a new fabrication method based on combining the additive 3D structuring capability laser photopolymerization and the substractive sub-wavelength resolution patterning of focused ion beam lithography to produce micro-optical elements capable of compound functionality. As a case in point of this approach binary spiral zone pattern based high numerical aperture micro-lenses capable of generating topological charge carrying tightly focused vortex beams in a single wavefront transformation step are presented. The devices were modelled using finite-difference time-domain simulations, and the theoretical predictions were verified by optically characterizing the propagation properties of light transmitted through the fabricated structures. The resulting devices had focal lengths close to the predicted values of f = 18 µm and f = 13 µm as well as topological charge ℓ dependent vortex focal spot sizes of ~ 1:3 µm and ~ 2:0 µm for ℓ = 1 and ℓ = 2 respectively.

  5. Volume-of-change cone-beam CT for image-guided surgery

    Lee, Junghoon; Webster Stayman, J.; Otake, Yoshito; Schafer, Sebastian; Zbijewski, Wojciech; Khanna, A. Jay; Prince, Jerry L.; Siewerdsen, Jeffrey H.

    2012-08-01

    C-arm cone-beam CT (CBCT) can provide intraoperative 3D imaging capability for surgical guidance, but workflow and radiation dose are the significant barriers to broad utilization. One main reason is that each 3D image acquisition requires a complete scan with a full radiation dose to present a completely new 3D image every time. In this paper, we propose to utilize patient-specific CT or CBCT as prior knowledge to accurately reconstruct the aspects of the region that have changed by the surgical procedure from only a sparse set of x-rays. The proposed methods consist of a 3D-2D registration between the prior volume and a sparse set of intraoperative x-rays, creating digitally reconstructed radiographs (DRRs) from the registered prior volume, computing difference images by subtracting DRRs from the intraoperative x-rays, a penalized likelihood reconstruction of the volume of change (VOC) from the difference images, and finally a fusion of VOC reconstruction with the prior volume to visualize the entire surgical field. When the surgical changes are local and relatively small, the VOC reconstruction involves only a small volume size and a small number of projections, allowing less computation and lower radiation dose than is needed to reconstruct the entire surgical field. We applied this approach to sacroplasty phantom data obtained from a CBCT test bench and vertebroplasty data with a fresh cadaver acquired from a C-arm CBCT system with a flat-panel detector. The VOCs were reconstructed from a varying number of images (10-66 images) and compared to the CBCT ground truth using four different metrics (mean squared error, correlation coefficient, structural similarity index and perceptual difference model). The results show promising reconstruction quality with structural similarity to the ground truth close to 1 even when only 15-20 images were used, allowing dose reduction by the factor of 10-20.

  6. Dose cone-beam CT alter treatment plans? Comparison of preoperative implant planning using panoramic versus cone-beam CT images

    Guerrero, Maria Eugenia; Jacobs, Reinhilde [Dept. of Oral and Maxillofacial Surgery, University Hospitals, Leuven (Belgium); Norge, Jorge; Castro, Carmen [Master of Periodontology, Universidad San Martin de Porres, Lima (Peru)

    2014-06-15

    The present study was performed to compare the planning of implant placement based on panoramic radiography (PAN) and cone-beam computed tomography (CBCT) images, and to study the impact of the image dataset on the treatment planning. One hundred five partially edentulous patients (77 males, 28 females, mean age: 46 years, range: 26-67 years) seeking oral implant rehabilitation were referred for presurgical imaging. Imaging consisted of PAN and CBCT imaging. Four observers planned implant treatment based on the two-dimensional (2D) image datasets and at least one month later on the three-dimensional (3D) image dataset. Apart from presurgical diagnostic and dimensional measurement tasks, the observers needed to indicate the surgical confidence levels and assess the image quality in relation to the presurgical needs. All observers confirmed that both imaging modalities (PAN and CBCT) gave similar values when planning implant diameter. Also, the results showed no differences between both imaging modalities for the length of implants with an anterior location. However, significant differences were found in the length of implants with a posterior location. For implant dimensions, longer lengths of the implants were planned with PAN, as confirmed by two observers. CBCT provided images with improved scores for subjective image quality and surgical confidence levels. Within the limitations of this study, there was a trend toward PAN-based preoperative planning of implant placement leading towards the use of longer implants within the posterior jaw bone.

  7. New aspects of whistler waves driven by an electron beam studied by a 3-D electromagnetic code

    Nishikawa, Ken-Ichi; Buneman, Oscar; Neubert, Torsten

    1994-01-01

    We have restudied electron beam driven whistler waves with a 3-D electromagnetic particle code. The simulation results show electromagnetic whistler wave emissions and electrostatic beam modes like those observed in the Spacelab 2 electron beam experiment. It has been suggested in the past that the spatial bunching of beam electrons associated with the beam mode may directly generate whistler waves. However, the simulation results indicate several inconsistencies with this picture: (1) whistler waves continue to be generated even after the beam mode space charge modulation looses its coherence, (2) the parallel (to the background magnetic field) wavelength of the whistler wave is longer than that of the beam instability, and (3) the parallel phase velocity of the whistler wave is smaller than that of the beam mode. The complex structure of the whistler waves in the vicinity of the beam suggest that the transverse motion (gyration) of the beam and background electrons is also involved in the generation of whistler waves.

  8. Focusing optics of a parallel beam CCD optical tomography apparatus for 3D radiation gel dosimetry.

    Krstajić, Nikola; Doran, Simon J

    2006-04-21

    Optical tomography of gel dosimeters is a promising and cost-effective avenue for quality control of radiotherapy treatments such as intensity-modulated radiotherapy (IMRT). Systems based on a laser coupled to a photodiode have so far shown the best results within the context of optical scanning of radiosensitive gels, but are very slow ( approximately 9 min per slice) and poorly suited to measurements that require many slices. Here, we describe a fast, three-dimensional (3D) optical computed tomography (optical-CT) apparatus, based on a broad, collimated beam, obtained from a high power LED and detected by a charged coupled detector (CCD). The main advantages of such a system are (i) an acquisition speed approximately two orders of magnitude higher than a laser-based system when 3D data are required, and (ii) a greater simplicity of design. This paper advances our previous work by introducing a new design of focusing optics, which take information from a suitably positioned focal plane and project an image onto the CCD. An analysis of the ray optics is presented, which explains the roles of telecentricity, focusing, acceptance angle and depth-of-field (DOF) in the formation of projections. A discussion of the approximation involved in measuring the line integrals required for filtered backprojection reconstruction is given. Experimental results demonstrate (i) the effect on projections of changing the position of the focal plane of the apparatus, (ii) how to measure the acceptance angle of the optics, and (iii) the ability of the new scanner to image both absorbing and scattering gel phantoms. The quality of reconstructed images is very promising and suggests that the new apparatus may be useful in a clinical setting for fast and accurate 3D dosimetry.

  9. Clinical utility of dental cone-beam computed tomography: current perspectives

    Jaju PP

    2014-04-01

    Full Text Available Prashant P Jaju,1 Sushma P Jaju21Oral Medicine and Radiology, 2Conservative Dentistry and Endodontics, Rishiraj College of Dental Sciences and Research Center, Bhopal, IndiaAbstract: Panoramic radiography and computed tomography were the pillars of maxillofacial diagnosis. With the advent of cone-beam computed tomography, dental practice has seen a paradigm shift. This review article highlights the potential applications of cone-beam computed tomography in the fields of dental implantology and forensic dentistry, and its limitations in maxillofacial diagnosis.Keywords: dental implants, cone-beam computed tomography, panoramic radiography, computed tomography

  10. Is there a role for the use of volumetric cone beam computed tomography in periodontics?

    du Bois, A H; Kardachi, B; Bartold, P M

    2012-03-01

    Volumetric computed cone beam tomography offers a number of significant advantages over conventional intraoral and extraoral panoramic radiography, as well as computed tomography. To date, periodontal diagnosis has relied heavily on the assessment of both intraoral radiographs and extraoral panoramic radiographs. With emerging technology in radiology there has been considerable interest in the role that volumetric cone beam computed tomography might play in periodontal diagnostics. This narrative reviews the current evidence and considers whether there is a role for volumetric cone beam computed tomography in periodontics.

  11. 3D printing in dentistry.

    Dawood, A; Marti Marti, B; Sauret-Jackson, V; Darwood, A

    2015-12-01

    3D printing has been hailed as a disruptive technology which will change manufacturing. Used in aerospace, defence, art and design, 3D printing is becoming a subject of great interest in surgery. The technology has a particular resonance with dentistry, and with advances in 3D imaging and modelling technologies such as cone beam computed tomography and intraoral scanning, and with the relatively long history of the use of CAD CAM technologies in dentistry, it will become of increasing importance. Uses of 3D printing include the production of drill guides for dental implants, the production of physical models for prosthodontics, orthodontics and surgery, the manufacture of dental, craniomaxillofacial and orthopaedic implants, and the fabrication of copings and frameworks for implant and dental restorations. This paper reviews the types of 3D printing technologies available and their various applications in dentistry and in maxillofacial surgery.

  12. Implementation of sensitivity and resolution modeling for SPECT with cone-beam collimator

    Krol, Andrzej; Kunniyur, Vikram R.; Lee, Wei; Gangal, Kedar R.; Coman, Ioana L.; Lipson, Edward D.; Karczewski, Deborah A.; Thomas, F. Deaver; Feiglin, David H.

    2005-04-01

    We implemented a fully-3D ordered-subsets expectation-maximization (OSEM) algorithm with attenuation compensation, distance-dependent blurring (DDB), and sensitivity modeling for SPECT performed with a cone-beam collimator (CBC). The experimentally obtained detector response to point sources across FOV was fitted to a two-dimensional Gaussian function with its width (FWHM) varying linearly with the source-to-detector distance and with very weak sensitivity dependence on the emission angle. We obtained CBC SPECT scans of a physical point-source phantom, a Defrise phantom, and a female patient, and we investigated performance of our algorithm. To correctly simulate DDB and sensitivity, a blurring kernel with a radius of up to 10 elements had to be used for a 128¥128 acquisition matrix, and volumetric ray tracing rather than line-element-based ray tracing has to be implemented. In the point-source phantom reconstruction we evaluated the uniformity of FWHM for the radial, tangential and longitudinal directions, and sensitivity vs. distance. An isotropic and stationary resolution was obtained at any location by OSEM with DDB and sensitivity modeling, only when volumetric ray tracing was used. We analyzed axial and transaxial profiles obtained for the Defrise phantom and evaluated the reconstructed breast SPECT patient images. The proposed fully-3D OSEM reconstruction algorithm with DBB and sensitivity modeling, and attenuation compensation with volumetric rays tracing is efficient and effective with significant resolution and sensitivity recovery.

  13. Cone-beam computed tomography as a surgical guide to impacted anterior teeth

    Fabiano Jeremias

    2016-01-01

    Full Text Available Surgical procedure for removal of impacted teeth is a challenge for clinicians as it involves accuracy in the diagnosis and localization of the dental elements. The cone-beam computed tomography (CBCT, compared to the conventional radiography, has a greater potential to provide complementary information because of its three-dimensional (3D images, reducing the possibility of failures in surgical procedures. Two 10-year-old boys presented with aesthetic issues associated with the juxtaposition of ectopic teeth with the permanent ones. Both two-dimensional and 3D preoperative radiographic diagnostic sets were produced. The occlusal and panoramic radiographs were not enough for proper localization of impacted incisors. Thus, the CBCT was used as a surgical guide. After 2 years of longitudinal following, no lesion was recorded, and the orthodontic treatment has proven successful. In all cases, CBCT contributed to both diagnosis and correct localization of supernumerary teeth, aiding the professional in the treatment planning, and consequently in the clinical success. The surgeries were completely safe, avoiding damage in noble structures, and providing a better recovering of the patients.

  14. Observer Reliability of Three-Dimensional Cephalometric Landmark Identification on Cone-Beam CT

    de Oliveira, Ana Emilia F.; Cevidanes, Lucia Helena S.; Phillips, Ceib; Motta, Alexandre; Burke, Brandon; Tyndall, Donald

    2009-01-01

    Objective To evaluate reliability in 3D landmark identification using Cone-Beam CT. Study Design Twelve pre-surgery CBCTs were randomly selected from 159 orthognathic surgery patients. Three observers independently repeated three times the identification of 30 landmarks in the sagittal, coronal, and axial slices. A mixed effects ANOVA model estimated the Intraclass Correlations (ICC) and assessed systematic bias. Results The ICC was >0.9 for 86% of intra-observer assessments and 66% of inter-observer assessments. Only 1% of intra-observer and 3% of inter-observer coefficients were <0.45. The systematic difference among observers was greater in X and Z than in Y dimensions, but the maximum mean difference was quite small. Conclusion Overall, the intra- and inter-observer reliability was excellent. 3D landmark identification using CBCT can offer consistent and reproducible data, if a protocol for operator training and calibration is followed. This is particularly important for landmarks not easily specified in all three planes of space. PMID:18718796

  15. [Endodontics in motion: new concepts, materials and techniques 2. The use of cone-beam computed tomography in endodontic diagnosis and treatment planning].

    Özok, A R; Metska, M E

    2015-09-01

    Systems for cone-beam computed tomography make a high-quality 3D reconstruction of dentomaxillofacial structures possible, without exposing the patient to excessive doses of radiation. Due to its 3D nature cone-beam computed tomography is superior to conventional dental radiographic imaging methods for many aspects of endodontic diagnosis and treatment planning. There are multiple indications for the use of cone-beam computed tomography scans in endodontics, including detection of periapical lesions or root fractures and the exploration of the root canal anatomy and its deviations. Depending on conditions, a judicious decision will always have to be made with regard to the radiographic technique to be applied. Primary in that respect must be the means by which the most accurate diagnostic image can be achieved with the lowest possible dose of radiation. Making a cone-beam computed tomography scan is justified only when the required diagnostic information cannot be achieved adequately using lower dose conventional dental radiographic imaging techniques.

  16. Cone-beam CT in diagnosis of scaphoid fractures

    Edlund, Rolf; Lapidus, Gunilla; Baecklund, Jenny [Capio St Goeran' s Hospital, Department of Radiology, Stockholm (Sweden); Skorpil, Mikael [Karolinska University Hospital, Department of Radiology, Stockholm (Sweden); Karolinska Institutet, Department of Molecular Medicine and Surgery, Stockholm (Sweden)

    2016-02-15

    This prospective study investigated the sensitivity of cone beam computed tomography (CBCT), a low dose technique recently made available for extremity examinations, in detecting scaphoid fractures. Magnetic resonance imaging (MRI) was used as gold standard for scaphoid fractures. A total of 95 patients with a clinically suspected scaphoid fracture were examined with radiography and CBCT in the acute setting. A negative CBCT exam was followed by an MRI within 2 weeks. When a scaphoid fracture was detected on MRI a new CBCT was performed. Radiography depicted seven scaphoid fractures, all of which were also seen with CBCT. CBCT detected another four scaphoid fractures. With MRI another five scaphoid fractures were identified that were not seen with radiography or with CBCT. These were also not visible on the reexamination CBCT. Sensitivity for radiography was 44, 95 % confidence interval 21-69 %, and for CBCT 69 %, 95 % confidence interval 41-88 % (p = 0.12). Several non-scaphoid fractures in the carpal region were identified, radiography and CBCT depicted 7 and 34, respectively (p < 0.0001). CBCT is a superior alternative to radiography, entailing more accurate diagnoses of carpal region fractures, and thereby requiring fewer follow-up MRI examinations. However, CBCT cannot be used to exclude scaphoid fractures, since MRI identified additional occult scaphoid fractures. (orig.)

  17. Bone changes of mandibular condyle using cone beam computed tomography

    Lee, Ji Un; Kim, Hyung Seop; Song, Ju Seop; Kim, Kyoung A; Koh, Kwang Joon [Chonbuk National Univ., Chonju (Korea, Republic of)

    2007-09-15

    To assess bone changes of mandibular condyle using cone beam computed tomography (CBCT) in temporomandibualr disorder (TMD) patients. 314 temporomandibular joints (TMJs) images of 163 TMD patients were examined at the Department of Oral and Maxillofacial Radiology, Chonbuk National University. The images were obtained by PSR9000N (Asahi Roentgen Co., Japan) and reconstructed by using Asahivision software (Asahi Roentgen Co., Japan). The CBCT images were examined three times with four weeks interval by three radiologists. Bone changes of mandibular condyle such as flattening, sclerosis, erosion and osteophyte formation were observed in sagittal, axial, coronal and 3 dimensional images of the mandibular condyle. The statistical analysis was performed using SPSS 12.0. Intra-and interobserver agreement were performed by 3 radiologists without the knowledge of clinical information. Osteopathy (2.9%) was found more frequently on anterior surface of the mandibular condyle. Erosion (31.8%) was found more frequently on anterior surface of the mandibular condyle. The intraobserver agreement was good to excellent (k=0.78{sub 0}.84), but interobserver agreement was fair (k=0.45). CBCT can provide high qualified images of bone changes of the TMJ with axial, coronal and 3 dimensional images.

  18. Use of dentomaxillofacial cone beam computed tomography in dentistry

    K?van?; Kamburo?lu

    2015-01-01

    Cone-beam computed tomography(CBCT) was developed and introduced specifically for dento-maxillofacial imaging. CBCT possesses a number of advantages over medical CT in clinical practice, such as lower effective radiation doses, lower costs, fewer space requirements,easier image acquisition, and interactive display modes such as mutiplanar reconstruction that are applicable to maxillofacial imaging. However, the disadvantages of CBCT include higher doses than two-dimensional imaging; the inability to accurately represent the internal structure of soft tissues and soft-tissue lesions; a limited correlation with Hounsfield Units for standardized quantification of bone density; and the presence of various types of image artifacts, mainly those produced by metal restorations. CBCT is now commonly used for a variety of purposes in oral implantology, dentomaxillofacial surgery, image-guided surgical procedures, endodontics, periodontics and orthodontics. CBCT applications provide obvious benefits in the assessment of dentomaxillofacial region, however; it should be used only in correct indications considering the necessity and the potential hazards of the examination.

  19. Cone beam computed tomography findings of impacted upper canines

    Da Silva Santos, Ludmilla Mota [Dept. of Endodontics, Aracatuba Dental School, Paulista State University, Aracatuba(Brazil); Bastos, Luana Costa; Da Silva, Silvio Jose Albergaria; Campos, Paulo Sergio Flores [School of Dentistry, Federal University of Bahia, Salvador (Brazil); Oliveira Santos, Christiano [Dept. of Stomatology, Oral Public Health, and Forensic Dentistry, School of Dentistry, University of Sao Paulo, Ribeirao Preto (Brazil); Neves, Frederico Sampaio [Dept. of Oral Diagnosis, Piracicaba Dental School, State University of Campinas, Piracicaba (Brazil)

    2014-12-15

    To describe the features of impacted upper canines and their relationship with adjacent structures through three-dimensional cone-beam computed tomography (CBCT) images. Using the CBCT scans of 79 upper impacted canines, we evaluated the following parameters: gender, unilateral/bilateral occurrence, location, presence and degree of root resorption of adjacent teeth (mild, moderate, or severe), root dilaceration, dental follicle width, and presence of other associated local conditions. Most of the impacted canines were observed in females (56 cases), unilaterally (51 cases), and at a palatine location (53 cases). Root resorption in adjacent teeth and root dilaceration were observed in 55 and 47 impacted canines, respectively. In most of the cases, the width of the dental follicle of the canine was normal; it was abnormally wide in 20 cases. A statistically significant association was observed for all variables, except for root dilaceration (p=0.115) and the side of impaction (p=0.260). Root resorption of adjacent teeth was present in most cases of canine impaction, mostly affecting adjacent lateral incisors to a mild degree. A wide dental follicle of impacted canines was not associated with a higher incidence of external root resorption of adjacent teeth.

  20. [Role of cone-beam computed tomography in diagnostic otorhinolaryngological imaging].

    Perényi, Ádám; Bella, Zsolt; Baráth, Zoltán; Magyar, Péter; Nagy, Katalin; Rovó, László

    2016-01-10

    Accurate diagnosis and preoperative planning in modern otorhinolaryngology is strongly supported by imaging with enhanced visualization. Computed tomography is often used to examine structures within bone frameworks. Given the hazards of ionizing radiation, repetitive imaging studies exponentially increase the risk of damages to radiosensitive tissues. The authors compare multislice and cone-beam computed tomography and determine the role, advantages and disadvantages of cone-beam computed tomography in otorhinolaryngological imaging. They summarize the knowledge from the international literature and their individual imaging studies. They conclude that cone-beam computed tomography enables high-resolution imaging and reconstruction in any optional plane and in space with considerably lower effective radiation dose. Cone-beam computed tomography with appropriate indications proved to be an excellent diagnostic tool in otorhinolaryngological imaging. It makes an alternative to multislice computed tomography and it is an effective tool in perioperative and postoperative follow-up, especially in those cases which necessitate repetitive imaging with computed tomography.

  1. Descriptive study of apical periodontitis detected in Cone Beam Computed Tomography scans

    MORETI,Lucieni Cristina Trovati; PANZARELLA,Francine Kühl; OLIVEIRA,Marine de; José Luiz Cintra JUNQUEIRA; MANHÃES JÚNIOR,Luiz Roberto

    2016-01-01

    ABSTRACT Objective: To perform a descriptive study in order to evaluate apical periodontitis in endodontically treated teeth using cone beam computed tomography. Methods: Eighty-six exams presenting at least one apical periodontitis were selected and divided into two groups: 1 for the mandible and 2 for the maxilla. All the exams were done using the same cone beam computed tomography with standard acquisition settings. All the images were processed and manipulated using the same software. T...

  2. Dental cone beam computed tomography: justification for use in planning oral implant placement.

    Jacobs, Reinhilde; Quirynen, Marc

    2014-10-01

    Intra-oral and panoramic radiographs are most frequently used in oral health care. Yet, the inherent nature of jaws and teeth renders three-dimensional diagnosis essential, especially in relation to oral surgery. Nowadays, this can be accomplished by dental cone beam computed tomography, which provides high-quality images at low radiation doses and low costs. Nonetheless, the effective dose ranges of cone beam computed tomography machines may easily vary from 10 to 1000 μSv, this being equivalent to two to 200 panoramic radiographs, even for similar presurgical indications. Moreover, the diagnostic image quality varies massively among available machines and parameter settings. Apart from the radiodiagnostic possibilities, dental cone beam computed tomography may offer a vast therapeutic potential, including opportunities for surgical guidance and further prosthetic rehabilitation via computer-aided design/computer-aided manufacturing solutions. These additional options may definitely explain part of the success of cone beam computed tomography for oral implant placement. In conclusion, dental cone beam computed tomography imaging could be justified for oral implant-related diagnosis, planning and transfer to surgical and further prosthetic treatment, but guidelines for justification and cone beam computed tomography optimization remain mandatory.

  3. FreeCAD visualization of realistic 3D physical optics beams within a CAD system-model

    Gayer, D.; O'Sullivan, C.; Scully, S.; Burke, D.; Brossard, J.; Chapron, C.

    2016-07-01

    The facility to realise the shape and extent of optical beams within a telescope or beamcombiner can aid greatly in the design and layout of optical elements within the system. It can also greatly facilitate communication between the optical design team and other teams working on the mechanical design of an instrument. Beyond the realm where raytracing is applicable however, it becomes much more difficult to realise accurate 3D beams which incorporate diffraction effects. It then is another issue to incorporate this into a CAD model of the system. A novel method is proposed which has been used to aid with the design of an optical beam combiner for the QUBIC (Q and U Bolometric Interferometer for Cosmology) 1 experiment operating at 150 GHz and 220 GHz. The method combines calculation work in GRASP 2, a commercial physical optics modelling tool from TICRA, geometrical work in Mathematica, and post processing in MATLAB. Finally, the Python console of the open source package FreeCAD3 is exploited to realise the 3D beams in a complete CAD system-model of the QUBIC optical beam combiner. This paper details and explains the work carried out to reach the goal and presents some graphics of the outcome. 3D representations of beams from some back-to-back input horns of the QUBIC instrument are shown within the CAD model. Beams of the -3dB and -13dB contour envelope are shown as well as envelopes enclosing 80% and 95% of the power of the beam. The ability to see these beams in situ with all the other elements of the combiner such as mirrors, cold stop, beam splitter and cryostat widows etc. greatly simplified the design for these elements and facilitated communication of element dimension and location between different subgroups within the QUBIC group.

  4. A prototype fan-beam optical CT scanner for 3D dosimetry

    Campbell, Warren G.; Rudko, D. A.; Braam, Nicolas A.; Jirasek, Andrew [University of Victoria, Victoria, British Columbia V8P 5C2 (Canada); Wells, Derek M. [British Columbia Cancer Agency, Vancouver Island Centre, Victoria, British Columbia V8R 6V5 (Canada)

    2013-06-15

    Purpose: The objective of this work is to introduce a prototype fan-beam optical computed tomography scanner for three-dimensional (3D) radiation dosimetry. Methods: Two techniques of fan-beam creation were evaluated: a helium-neon laser (HeNe, {lambda} = 543 nm) with line-generating lens, and a laser diode module (LDM, {lambda} = 635 nm) with line-creating head module. Two physical collimator designs were assessed: a single-slot collimator and a multihole collimator. Optimal collimator depth was determined by observing the signal of a single photodiode with varying collimator depths. A method of extending the dynamic range of the system is presented. Two sample types were used for evaluations: nondosimetric absorbent solutions and irradiated polymer gel dosimeters, each housed in 1 liter cylindrical plastic flasks. Imaging protocol investigations were performed to address ring artefacts and image noise. Two image artefact removal techniques were performed in sinogram space. Collimator efficacy was evaluated by imaging highly opaque samples of scatter-based and absorption-based solutions. A noise-based flask registration technique was developed. Two protocols for gel manufacture were examined. Results: The LDM proved advantageous over the HeNe laser due to its reduced noise. Also, the LDM uses a wavelength more suitable for the PRESAGE{sup TM} dosimeter. Collimator depth of 1.5 cm was found to be an optimal balance between scatter rejection, signal strength, and manufacture ease. The multihole collimator is capable of maintaining accurate scatter-rejection to high levels of opacity with scatter-based solutions (T < 0.015%). Imaging protocol investigations support the need for preirradiation and postirradiation scanning to reduce reflection-based ring artefacts and to accommodate flask imperfections and gel inhomogeneities. Artefact removal techniques in sinogram space eliminate streaking artefacts and reduce ring artefacts of up to {approx}40% in magnitude. The

  5. A system to track skin dose for neuro-interventional cone-beam computed tomography (CBCT)

    Vijayan, Sarath; Xiong, Zhenyu; Rudin, Stephen; Bednarek, Daniel R.

    2016-03-01

    The skin-dose tracking system (DTS) provides a color-coded illustration of the cumulative skin-dose distribution on a closely-matching 3D graphic of the patient during fluoroscopic interventions in real-time for immediate feedback to the interventionist. The skin-dose tracking utility of DTS has been extended to include cone-beam computed tomography (CBCT) of neurointerventions. While the DTS was developed to track the entrance skin dose including backscatter, a significant part of the dose in CBCT is contributed by exit primary radiation and scatter due to the many overlapping projections during the rotational scan. The variation of backscatter inside and outside the collimated beam was measured with radiochromic film and a curve was fit to obtain a scatter spread function that could be applied in the DTS. Likewise, the exit dose distribution was measured with radiochromic film for a single projection and a correction factor was determined as a function of path length through the head. Both of these sources of skin dose are added for every projection in the CBCT scan to obtain a total dose mapping over the patient graphic. Results show the backscatter to follow a sigmoidal falloff near the edge of the beam, extending outside the beam as far as 8 cm. The exit dose measured for a cylindrical CTDI phantom was nearly 10 % of the entrance peak skin dose for the central ray. The dose mapping performed by the DTS for a CBCT scan was compared to that measured with radiochromic film and a CTDI-head phantom with good agreement.

  6. Adjustable hollow-cone output x-ray beam from an ellipsoidal monocapillary with a pinhole and a beam stop.

    Sun, Xue-Peng; Liu, Zhi-Gou; Yi, Long-Tao; Sun, Wei-Yun; Li, Fang-Zou; Jiang, Bo-Wen; Ma, Yong-Zhong; Sun, Tian-Xi

    2015-12-10

    A combined shading system (CSS) consisting of a beam stop and a pinhole is proposed to be used between an ellipsoidal monocapillary (EM) and a conventional laboratory x-ray source to obtain an adjustable hollow-cone output beam for different experiments with no need for changing the EM. The CSS can change the incident x-ray beam on the EM by adjusting the position of the beam stop and the pinhole, with the corresponding change of the output beam of the EM. In this study, the adjustable hollow-cone output x-ray beam of an 80-mm-long EM with a CSS was studied in detail with a laboratory Cu x-ray generator with a focal spot diameter of 50 μm. The adjustable range of the focal spot size of the EM was from 8.6 to 58.7 μm. The adjustable range of the gain of the focal spot of the EM was from 0 to 1350. The beam divergence of the hollow-cone output beam of the EM ranged from 6 to 16.75 mrad. The illumination angle of the hollow-cone output beam of the EM ranged from 0 to 5.95 mrad. In addition, the potential application of the proposed adjusting method in testing the performance of the EM is briefly discussed.

  7. Stray light in cone beam optical computed tomography: I. Measurement and reduction strategies with planar diffuse source.

    Granton, Patrick V; Dekker, Kurtis H; Battista, Jerry J; Jordan, Kevin J

    2016-04-07

    Optical cone-beam computed tomographic (CBCT) scanning of 3D radiochromic dosimeters may provide a practical method for 3D dose verification in radiation therapy. However, in cone-beam geometry stray light contaminates the projection images, degrading the accuracy of reconstructed linear attenuation coefficients. Stray light was measured using a beam pass aperture array (BPA) and structured illumination methods. The stray-to-primary ray ratio (SPR) along the central axis was found to be 0.24 for a 5% gelatin hydrogel, representative of radiochromic hydrogels. The scanner was modified by moving the spectral filter from the detector to the source, changing the light's spatial fluence pattern and lowering the acceptance angle by extending distance between the source and object. These modifications reduced the SPR significantly from 0.24 to 0.06. The accuracy of the reconstructed linear attenuation coefficients for uniform carbon black liquids was compared to independent spectrometer measurements. Reducing the stray light increased the range of accurate transmission readings. In order to evaluate scanner performance for the more challenging application to small field dosimetry, a carbon black finger gel phantom was prepared. Reconstructions of the phantom from CBCT and fan-beam CT scans were compared. The modified source resulted in improved agreement. Subtraction of residual stray light, measured with BPA or structured illumination from each projection further improved agreement. Structured illumination was superior to BPA for measuring stray light for the smaller 1.2 and 0.5 cm diameter phantom fingers. At the costs of doubling the scanner size and tripling the number of scans, CBCT reconstructions of low-scattering hydrogel dosimeters agreed with those of fan-beam CT scans.

  8. Stray light in cone beam optical computed tomography: I. Measurement and reduction strategies with planar diffuse source

    Granton, Patrick V.; Dekker, Kurtis H.; Battista, Jerry J.; Jordan, Kevin J.

    2016-04-01

    Optical cone-beam computed tomographic (CBCT) scanning of 3D radiochromic dosimeters may provide a practical method for 3D dose verification in radiation therapy. However, in cone-beam geometry stray light contaminates the projection images, degrading the accuracy of reconstructed linear attenuation coefficients. Stray light was measured using a beam pass aperture array (BPA) and structured illumination methods. The stray-to-primary ray ratio (SPR) along the central axis was found to be 0.24 for a 5% gelatin hydrogel, representative of radiochromic hydrogels. The scanner was modified by moving the spectral filter from the detector to the source, changing the light’s spatial fluence pattern and lowering the acceptance angle by extending distance between the source and object. These modifications reduced the SPR significantly from 0.24 to 0.06. The accuracy of the reconstructed linear attenuation coefficients for uniform carbon black liquids was compared to independent spectrometer measurements. Reducing the stray light increased the range of accurate transmission readings. In order to evaluate scanner performance for the more challenging application to small field dosimetry, a carbon black finger gel phantom was prepared. Reconstructions of the phantom from CBCT and fan-beam CT scans were compared. The modified source resulted in improved agreement. Subtraction of residual stray light, measured with BPA or structured illumination from each projection further improved agreement. Structured illumination was superior to BPA for measuring stray light for the smaller 1.2 and 0.5 cm diameter phantom fingers. At the costs of doubling the scanner size and tripling the number of scans, CBCT reconstructions of low-scattering hydrogel dosimeters agreed with those of fan-beam CT scans.

  9. Acoustic Pressure Waves in Vibrating 3-D Laminated Beam-Plate Enclosures

    Charles A. Osheku

    2009-01-01

    Full Text Available The effect of structural vibration on the propagation of acoustic pressure waves through a cantilevered 3-D laminated beam-plate enclosure is investigated analytically. For this problem, a set of well-posed partial differential equations governing the vibroacoustic wave interaction phenomenon are formulated and matched for the various vibrating boundary surfaces. By employing integral transforms, a closed form analytical expression is computed suitable for vibroacoustic modeling, design analysis, and general aerospace defensive applications. The closed-form expression takes the form of a kernel of polynomials for acoustic pressure waves showing the influence of linear interface pressure variation across the axes of vibrating boundary surfaces. Simulated results demonstrate how the mode shapes and the associated natural frequencies can be easily computed. It is shown in this paper that acoustic pressure waves propagation are dynamically stable through laminated enclosures with progressive decrement in interfacial pressure distribution under the influence of high excitation frequencies irrespective of whether the induced flow is subsonic, sonic , supersonic, or hypersonic. Hence, in practice, dynamic stability of hypersonic aircrafts or jet airplanes can be further enhanced by replacing their noise transmission systems with laminated enclosures.

  10. A reconstruction method for cone-beam differential x-ray phase-contrast computed tomography.

    Fu, Jian; Velroyen, Astrid; Tan, Renbo; Zhang, Junwei; Chen, Liyuan; Tapfer, Arne; Bech, Martin; Pfeiffer, Franz

    2012-09-10

    Most existing differential phase-contrast computed tomography (DPC-CT) approaches are based on three kinds of scanning geometries, described by parallel-beam, fan-beam and cone-beam. Due to the potential of compact imaging systems with magnified spatial resolution, cone-beam DPC-CT has attracted significant interest. In this paper, we report a reconstruction method based on a back-projection filtration (BPF) algorithm for cone-beam DPC-CT. Due to the differential nature of phase contrast projections, the algorithm restrains from differentiation of the projection data prior to back-projection, unlike BPF algorithms commonly used for absorption-based CT data. This work comprises a numerical study of the algorithm and its experimental verification using a dataset measured with a three-grating interferometer and a micro-focus x-ray tube source. Moreover, the numerical simulation and experimental results demonstrate that the proposed method can deal with several classes of truncated cone-beam datasets. We believe that this feature is of particular interest for future medical cone-beam phase-contrast CT imaging applications.

  11. Radiation Exposure of Abdominal Cone Beam Computed Tomography

    Sailer, Anna M., E-mail: anni.sailer@mumc.nl [Maastricht University Medical Centre (MUMC), Department of Radiology (Netherlands); Schurink, Geert Willem H., E-mail: gwh.schurink@mumc.nl [Maastricht University Medical Centre, Department of Surgery (Netherlands); Wildberger, Joachim E., E-mail: j.wildberger@mumc.nl; Graaf, Rick de, E-mail: r.de.graaf@mumc.nl; Zwam, Willem H. van, E-mail: w.van.zwam@mumc.nl; Haan, Michiel W. de, E-mail: m.de.haan@mumc.nl; Kemerink, Gerrit J., E-mail: gerrit.kemerink@mumc.nl; Jeukens, Cécile R. L. P. N., E-mail: cecile.jeukens@mumc.nl [Maastricht University Medical Centre (MUMC), Department of Radiology (Netherlands)

    2015-02-15

    PurposeTo evaluate patients radiation exposure of abdominal C-arm cone beam computed tomography (CBCT).MethodsThis prospective study was approved by the institutional review board; written, informed consent was waived. Radiation exposure of abdominal CBCT was evaluated in 40 patients who underwent CBCT during endovascular interventions. Dose area product (DAP) of CBCT was documented and effective dose (ED) was estimated based on organ doses using dedicated Monte Carlo simulation software with consideration of X-ray field location and patients’ individual body weight and height. Weight-dependent ED per DAP conversion factors were calculated. CBCT radiation dose was compared to radiation dose of procedural fluoroscopy. CBCT dose-related risk for cancer was assessed.ResultsMean ED of abdominal CBCT was 4.3 mSv (95 % confidence interval [CI] 3.9; 4.8 mSv, range 1.1–7.4 mSv). ED was significantly higher in the upper than in the lower abdomen (p = 0.003) and increased with patients’ weight (r = 0.55, slope = 0.045 mSv/kg, p < 0.001). Radiation exposure of CBCT corresponded to the radiation exposure of on average 7.2 fluoroscopy minutes (95 % CI 5.5; 8.8 min) in the same region of interest. Lifetime risk of exposure related cancer death was 0.033 % or less depending on age and weight.ConclusionsMean ED of abdominal CBCT was 4.3 mSv depending on X-ray field location and body weight.

  12. Three-dimensional anisotropic adaptive filtering of projection data for noise reduction in cone beam CT

    Maier, Andreas; Wigstroem, Lars; Hofmann, Hannes G.; Hornegger, Joachim; Zhu Lei; Strobel, Norbert; Fahrig, Rebecca [Department of Radiology, Stanford University, Stanford, California 94305 (United States); Department of Radiology, Stanford University, Stanford, California 94305 (United States) and Center for Medical Image Science and Visualization, Linkoeping University, Linkoeping (Sweden); Pattern Recognition Laboratory, Department of Computer Science, Friedrich-Alexander University of Erlangen-Nuremberg, 91054, Erlangen (Germany); Nuclear and Radiological Engineering and Medical Physics Programs, George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Siemens AG Healthcare, Forchheim 91301 (Germany); Department of Radiology, Stanford University, Stanford, California 94305 (United States)

    2011-11-15

    .9-fold speed-up of the processing (from 1336 to 150 s). Conclusions: Adaptive anisotropic filtering has the potential to substantially improve image quality and/or reduce the radiation dose required for obtaining 3D image data using cone beam CT.

  13. Beam hardening correction for a cone-beam CT system and its effect on spatial resolution

    ZHAO Wei; WEI Long; YU Zhong-Qiang; FU Guo-Tao; SUN Cui-Li; WANG Yan-Fang; WEI Cun-Feng; CAO Da-Quan; QUE Jie-Min; TANG Xiao; SHI Rong-Jian

    2011-01-01

    In this paper,we present a beam hardening correction (BHC) method in three-dimension space for a cone-beam computed tomography (CBCT) system in a mono-material case and investigate its effect on the spatial resolution.Due to the polychromatic character of the X-ray spectrum used,cupping and streak artifacts called beam hardening artifacts arise in the reconstructed CT images,causing reduced image quality.In addition,enhanced edges are introduced in the reconstructed CT images because of the beam hardening effect.The spatial resolution of the CBCT system is calculated from the edge response function (ERF) on different planes in space.Thus,in the CT images with beam hardening artifacts,enhanced ERFs will be extracted to calculate the modulation transfer function (MTF),obtaining a better spatial resolution that deviates from the real value.Reasonable spatial resolution can be obtained after reducing the artifacts.The 10% MTF value and the full width at half maximum (FWHM) of the point spread function with and without BHC are presented.

  14. Evaluation of positioning errors of the patient using cone beam CT megavoltage; Evaluacion de errores de posicionamiento del paciente mediante Cone Beam CT de megavoltaje

    Garcia Ruiz-Zorrilla, J.; Fernandez Leton, J. P.; Zucca Aparicio, D.; Perez Moreno, J. M.; Minambres Moro, A.

    2013-07-01

    Image-guided radiation therapy allows you to assess and fix the positioning of the patient in the treatment unit, thus reducing the uncertainties due to the positioning of the patient. This work assesses errors systematic and errors of randomness from the corrections made to a series of patients of different diseases through a protocol off line of cone beam CT (CBCT) megavoltage. (Author)

  15. Cone-beam CT技术及其在口腔正畸学中的应用进展%Current advance in application of cone-beam CT in orthodontics

    王婷; 厉松

    2011-01-01

    在正畸的诊断治疗过程中,cone-beam CT已广泛应用于口腔界的各个领域,本文旨在对cone-beamCT的原理、特点及其在口腔正畸领域中的应用进行综述,以期增加正畸医师对于Cone-beam CT的理解.

  16. Measurement of the spatial resolution and the relative density resolution in an industrial cone-beam micro computed tomography system

    WANG Yan-Fang; QUE Jie-Min; CAO Da-Quan; SUN Cui-Li; ZHAO Wei; WEI Cun-Feng; SHI Rong-Jian

    2013-01-01

    The spatial resolution and the relative density resolution are the two most critical indicators in CT system.The method recommended in the ASTM E1695-95 and GJB 5311-2004 is only suitable to the fan-beam CT system.In this paper,for industrial cone-beam micro CT system,we will adopt the edge response function (ERF) created by the step edges of a steel ball to measure the system 3D PSF and MTF.To describe the contrast discrimination function more accurately,we will first propose to extend the two-dimensional measurement region to the three-dimensional space.Our experimental spatial resolution is (55.56±0.56) lp/mm and the relative density resolution is 1% within 300 μm×300 μm×300 μm according to the 3σ rule.

  17. Identification of dental root canals and their medial line from micro-CT and cone-beam CT records

    Benyó Balázs

    2012-10-01

    Full Text Available Abstract Background Shape of the dental root canal is highly patient specific. Automated identification methods of the medial line of dental root canals and the reproduction of their 3D shape can be beneficial for planning endodontic interventions as severely curved root canals or multi-rooted teeth may pose treatment challenges. Accurate shape information of the root canals may also be used by manufacturers of endodontic instruments in order to make more efficient clinical tools. Method Novel image processing procedures dedicated to the automated detection of the medial axis of the root canal from dental micro-CT and cone-beam CT records are developed. For micro-CT, the 3D model of the root canal is built up from several hundred parallel cross sections, using image enhancement, histogram based fuzzy c-means clustering, center point detection in the segmented slice, three dimensional inner surface reconstruction, and potential field driven curve skeleton extraction in three dimensions. Cone-beam CT records are processed with image enhancement filters and fuzzy chain based regional segmentation, followed by the reconstruction of the root canal surface and detecting its skeleton via a mesh contraction algorithm. Results The proposed medial line identification and root canal detection algorithms are validated on clinical data sets. 25 micro-CT and 36 cone-beam-CT records are used in the validation procedure. The overall success rate of the automatic dental root canal identification was about 92% in both procedures. The algorithms proved to be accurate enough for endodontic therapy planning. Conclusions Accurate medial line identification and shape detection algorithms of dental root canal have been developed. Different procedures are defined for micro-CT and cone-beam CT records. The automated execution of the subsequent processing steps allows easy application of the algorithms in the dental care. The output data of the image processing procedures

  18. Exact cone beam reconstruction formulae for functions and their gradients for spherical and flat detectors

    Louis, Alfred K.

    2016-11-01

    We derive unified inversion formulae for the cone beam transform similar to the Radon transform. Reinterpreting Grangeat’s formula we find a relation between the Radon transform of the gradient of the searched-for function and a quantity computable from cone beam data. This gives a uniqueness result for the cone beam transform of compactly supported functions under much weaker assumptions than the Tuy-Kirillov condition. Furthermore this relation leads to an exact formula for the direct calculation of derivatives of the density distribution; but here, similar to the classical Radon transform, complete Radon data are needed, hence the Tuy-Kirillov condition has to be imposed. Numerical experiments reported in Hahn B N et al (2013 Meas. Sci. Technol. 24 125601) indicate that these calculations are less corrupted by beam-hardening noise. Finally, we present flat detector versions for these results, which are mathematically less attractive but important for applications.

  19. Evaluation of the systematic error in using 3D dose calculation in scanning beam proton therapy for lung cancer.

    Li, Heng; Liu, Wei; Park, Peter; Matney, Jason; Liao, Zhongxing; Chang, Joe; Zhang, Xiaodong; Li, Yupeng; Zhu, Ronald X

    2014-09-08

    The objective of this study was to evaluate and understand the systematic error between the planned three-dimensional (3D) dose and the delivered dose to patient in scanning beam proton therapy for lung tumors. Single-field and multifield optimized scanning beam proton therapy plans were generated for ten patients with stage II-III lung cancer with a mix of tumor motion and size. 3D doses in CT datasets for different respiratory phases and the time-weighted average CT, as well as the four-dimensional (4D) doses were computed for both plans. The 3D and 4D dose differences for the targets and different organs at risk were compared using dose-volume histogram (DVH) and voxel-based techniques, and correlated with the extent of tumor motion. The gross tumor volume (GTV) dose was maintained in all 3D and 4D doses, using the internal GTV override technique. The DVH and voxel-based techniques are highly correlated. The mean dose error and the standard deviation of dose error for all target volumes were both less than 1.5% for all but one patient. However, the point dose difference between the 3D and 4D doses was up to 6% for the GTV and greater than 10% for the clinical and planning target volumes. Changes in the 4D and 3D doses were not correlated with tumor motion. The planning technique (single-field or multifield optimized) did not affect the observed systematic error. In conclusion, the dose error in 3D dose calculation varies from patient to patient and does not correlate with lung tumor motion. Therefore, patient-specific evaluation of the 4D dose is important for scanning beam proton therapy for lung tumors.

  20. Beam Test Studies of 3D Pixel Sensors Irradiated Non-Uniformly for the ATLAS Forward Physics Detector

    Grinstein, S; Boscardin, M; Christophersen, M; Da Via, C; Betta, G -F Dalla; Darbo, G; Fadeyev, V; Fleta, C; Gemme, C; Grenier, P; Jimenez, A; Lopez, I; Micelli, A; Nelist, C; Parker, S; Pellegrini, G; Phlips, B; Pohl, D L; Sadrozinski, H F -W; Sicho, P; Tsiskaridze, S

    2013-01-01

    Pixel detectors with cylindrical electrodes that penetrate the silicon substrate (so called 3D detectors) offer advantages over standard planar sensors in terms of radiation hardness, since the electrode distance is decoupled from the bulk thickness. In recent years significant progress has been made in the development of 3D sensors, which culminated in the sensor production for the ATLAS Insertable B-Layer (IBL) upgrade carried out at CNM (Barcelona, Spain) and FBK (Trento, Italy). Based on this success, the ATLAS Forward Physics (AFP) experiment has selected the 3D pixel sensor technology for the tracking detector. The AFP project presents a new challenge due to the need for a reduced dead area with respect to IBL, and the in-homogeneous nature of the radiation dose distribution in the sensor. Electrical characterization of the first AFP prototypes and beam test studies of 3D pixel devices irradiated non-uniformly are presented in this paper.

  1. Beam test studies of 3D pixel sensors irradiated non-uniformly for the ATLAS forward physics detector

    Grinstein, S., E-mail: sgrinstein@ifae.es [ICREA and Institut de Física d' Altes Energies (IFAE), Barcelona (Spain); Baselga, M. [Centro Nacional de Microelectronica, CNM-IMB (CSIC), Barcelona (Spain); Boscardin, M. [Fondazione Bruno Kessler, FBK-CMM, Trento (Italy); Christophersen, M. [U.S. Naval Research Laboratory, Washington (United States); Da Via, C. [School of Physics and Astronomy, University of Manchester, Manchester (United Kingdom); Dalla Betta, G.-F. [Universita degli Studi di Trento and INFN, Trento (Italy); Darbo, G. [INFN Sezione di Genova, Genova (Italy); Fadeyev, V. [Santa Cruz Institute for Particle Physics, University of California, Santa Cruz (United States); Fleta, C. [Centro Nacional de Microelectronica, CNM-IMB (CSIC), Barcelona (Spain); Gemme, C. [Universita degli Studi di Trento and INFN, Trento (Italy); Grenier, P. [SLAC National Accelerator Laboratory, Menlo Park (United States); Jimenez, A.; Lopez, I.; Micelli, A. [ICREA and Institut de Física d' Altes Energies (IFAE), Barcelona (Spain); Nelist, C. [INFN Sezione di Genova, Genova (Italy); Parker, S. [University of Hawaii, c/o Lawrence Berkeley Laboratory, Berkeley (United States); Pellegrini, G. [Centro Nacional de Microelectronica, CNM-IMB (CSIC), Barcelona (Spain); Phlips, B. [U.S. Naval Research Laboratory, Washington (United States); Pohl, D.-L. [University of Bonn, Bonn (Germany); Sadrozinski, H.F.-W. [Santa Cruz Institute for Particle Physics, University of California, Santa Cruz (United States); and others

    2013-12-01

    Pixel detectors with cylindrical electrodes that penetrate the silicon substrate (so called 3D detectors) offer advantages over standard planar sensors in terms of radiation hardness, since the electrode distance is decoupled from the bulk thickness. In recent years significant progress has been made in the development of 3D sensors, which culminated in the sensor production for the ATLAS Insertable B-Layer (IBL) upgrade carried out at CNM (Barcelona, Spain) and FBK (Trento, Italy). Based on this success, the ATLAS Forward Physics (AFP) experiment has selected the 3D pixel sensor technology for the tracking detector. The AFP project presents a new challenge due to the need for a reduced dead area with respect to IBL, and the in-homogeneous nature of the radiation dose distribution in the sensor. Electrical characterization of the first AFP prototypes and beam test studies of 3D pixel devices irradiated non-uniformly are presented in this paper.

  2. Analysis of the beam halo in negative ion sources by using 3D3V PIC code

    Miyamoto, K., E-mail: kmiyamot@naruto-u.ac.jp [Naruto University of Education, 748 Nakashima, Takashima, Naruto-cho, Naruto-shi, Tokushima 772-8502 (Japan); Nishioka, S.; Goto, I.; Hatayama, A. [Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522 (Japan); Hanada, M.; Kojima, A.; Hiratsuka, J. [Japan Atomic Energy Agency, 801-1 Mukouyama, Naka 319-0913 (Japan)

    2016-02-15

    The physical mechanism of the formation of the negative ion beam halo and the heat loads of the multi-stage acceleration grids are investigated with the 3D PIC (particle in cell) simulation. The following physical mechanism of the beam halo formation is verified: The beam core and the halo consist of the negative ions extracted from the center and the periphery of the meniscus, respectively. This difference of negative ion extraction location results in a geometrical aberration. Furthermore, it is shown that the heat loads on the first acceleration grid and the second acceleration grid are quantitatively improved compared with those for the 2D PIC simulation result.

  3. Analysis of the beam halo in negative ion sources by using 3D3V PIC code.

    Miyamoto, K; Nishioka, S; Goto, I; Hatayama, A; Hanada, M; Kojima, A; Hiratsuka, J

    2016-02-01

    The physical mechanism of the formation of the negative ion beam halo and the heat loads of the multi-stage acceleration grids are investigated with the 3D PIC (particle in cell) simulation. The following physical mechanism of the beam halo formation is verified: The beam core and the halo consist of the negative ions extracted from the center and the periphery of the meniscus, respectively. This difference of negative ion extraction location results in a geometrical aberration. Furthermore, it is shown that the heat loads on the first acceleration grid and the second acceleration grid are quantitatively improved compared with those for the 2D PIC simulation result.

  4. Actively triggered 4d cone-beam CT acquisition

    Fast, Martin F.; Wisotzky, Eric [German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, D-69120 Heidelberg (Germany); Oelfke, Uwe; Nill, Simeon [Joint Department of Physics, The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, Downs Road, Sutton, Surrey SM2 5PT (United Kingdom)

    2013-09-15

    Purpose: 4d cone-beam computed tomography (CBCT) scans are usually reconstructed by extracting the motion information from the 2d projections or an external surrogate signal, and binning the individual projections into multiple respiratory phases. In this “after-the-fact” binning approach, however, projections are unevenly distributed over respiratory phases resulting in inefficient utilization of imaging dose. To avoid excess dose in certain respiratory phases, and poor image quality due to a lack of projections in others, the authors have developed a novel 4d CBCT acquisition framework which actively triggers 2d projections based on the forward-predicted position of the tumor.Methods: The forward-prediction of the tumor position was independently established using either (i) an electromagnetic (EM) tracking system based on implanted EM-transponders which act as a surrogate for the tumor position, or (ii) an external motion sensor measuring the chest-wall displacement and correlating this external motion to the phase-shifted diaphragm motion derived from the acquired images. In order to avoid EM-induced artifacts in the imaging detector, the authors devised a simple but effective “Faraday” shielding cage. The authors demonstrated the feasibility of their acquisition strategy by scanning an anthropomorphic lung phantom moving on 1d or 2d sinusoidal trajectories.Results: With both tumor position devices, the authors were able to acquire 4d CBCTs free of motion blurring. For scans based on the EM tracking system, reconstruction artifacts stemming from the presence of the EM-array and the EM-transponders were greatly reduced using newly developed correction algorithms. By tuning the imaging frequency independently for each respiratory phase prior to acquisition, it was possible to harmonize the number of projections over respiratory phases. Depending on the breathing period (3.5 or 5 s) and the gantry rotation time (4 or 5 min), between ∼90 and 145

  5. Benign Prostatic Hyperplasia: Cone-Beam CT in Conjunction with DSA for Identifying Prostatic Arterial Anatomy.

    Wang, Mao Qiang; Duan, Feng; Yuan, Kai; Zhang, Guo Dong; Yan, Jieyu; Wang, Yan

    2017-01-01

    Purpose To describe findings in prostatic arteries (PAs) at digital subtraction angiography (DSA) and cone-beam computed tomography (CT) that allow identification of benign prostatic hyperplasia and to determine the value added with the use of cone-beam CT. Materials and Methods This retrospective single-institution study was approved by the institutional review board, and the requirement for written informed consent was waived. From February 2009 to December 2014, a total of 148 patients (mean age ± standard deviation, 70.5 years ± 14.5) underwent DSA of the internal iliac arteries and cone-beam CT with a flat-detector angiographic system before they underwent prostate artery embolization. Both the DSA and cone-beam CT images were evaluated by two interventional radiologists to determine the number of independent PAs and their origins and anastomoses with adjacent arteries. The exact McNemar test was used to compare the detection rate of the PAs and the anastomoses with DSA and with cone-beam CT. Results The PA anatomy was evaluated successfully by means of cone-beam CT in conjunction with DSA in all patients. Of the 296 pelvic sides, 274 (92.6%) had only one PA. The most frequent PA origin was the common gluteal-pudendal trunk with the superior vesicular artery in 118 (37.1%), followed by the anterior division of the internal iliac artery in 99 (31.1%), and the internal pudendal artery in 77 (24.2%) pelvic sides. In 67 (22.6%) pelvic sides, anastomoses to adjacent arteries were documented. The numbers of PA origins and anastomoses, respectively, that could be identified were significantly higher with cone-beam CT (301 of 318 [94.7%] and 65 of 67 [97.0%]) than with DSA (237 [74.5%] and 39 [58.2%], P Cone-beam CT provided essential information that was not available with DSA in 90 of 148 (60.8%) patients. Conclusion Cone-beam CT is a useful adjunctive technique to DSA for identification of the PA anatomy and provides information to help treatment planning during

  6. Dosimetry of cone beam computed tomography scanning for diagnosis and planning in implant dentistry

    Santos Pinto de A, E. L.; Manzi, F. R.; Goncalves Z, E. [Pontifical Catholic University of Minas Gerais, Av. Jose Gaspar 500, 30535-901 Belo Horizonte, Minas Gerais (Brazil); Nogueira, M. S.; Fernandes Z, M. A., E-mail: madelon@cdtn.br [Development Center of Nuclear Technology / CNEN, Av. Pte. Antonio Carlos 6627, 31270-901Belo Horizonte, Minas Gerais (Brazil)

    2015-10-15

    Full text: The radiation dose and estimate the radiation induced risk of cancer and morpho functional alterations according to BEIR VII (2006) and recommendations of the ICRP 103 (2007) were measured in cone beam computed tomography (CBCT) scanning (Tc Kodak 9000C 3D) in different oral and maxillofacial regions for diagnosis and planning in implant dentistry for each examination protocol: jaw full, maxilla full and jaw and maxilla full associated. Thermoluminescent dosimeters (TLD- 100 H) were placed in an Alderson-Rando in regions corresponding to the crystalline, parotid, submandibular and thyroid glands and ovaries. The highest values for entrance skin dose were observed in the region of the parotid and submandibular glands, 9.612 mGy to 7.912 mGy and 8.818 mGy to 0.483 mGy, respectively. All examination protocols presented on the right and left sides in the region of the submandibular gland the highest values for absorbed dose (D). In the jaw full exam the thyroid glands on both sides presented highest dose values than maxilla full exam. This study allowed measuring the entrance skin dose and the absorbed dose (D) highlighting a dosimetric preponderance to the salivary glands. With danger of to radiation that induces cancer risk was observed that the age group most likely to have to risk of cancer was 20 years, compared to 30, 40, 50, 60,70 and 80 years. (Author)

  7. The current status of cone beam computed tomography imaging in orthodontics.

    Kapila, S; Conley, R S; Harrell, W E

    2011-01-01

    Cone beam CT (CBCT) has become an increasingly important source of three dimensional (3D) volumetric data in clinical orthodontics since its introduction into dentistry in 1998. The purpose of this manuscript is to highlight the current understanding of, and evidence for, the clinical use of CBCT in orthodontics, and to review the findings to answer clinically relevant questions. Currently available information from studies using CBCT can be organized into five broad categories: 1, the assessment of CBCT technology; 2, its use in craniofacial morphometric analyses; 3, incidental and missed findings; 4, analysis of treatment outcomes; and 5, efficacy of CBCT in diagnosis and treatment planning. The findings in these topical areas are summarized, followed by current indications and protocols for the use of CBCT in specific cases. Despite the increasing popularity of CBCT in orthodontics, and its advantages over routine radiography in specific cases, the effects of information derived from these images in altering diagnosis and treatment decisions has not been demonstrated in several types of cases. It has therefore been recommended that CBCT be used in select cases in which conventional radiography cannot supply satisfactory diagnostic information; these include cleft palate patients, assessment of unerupted tooth position, supernumerary teeth, identification of root resorption and for planning orthognathic surgery. The need to image other types of cases should be made on a case-by-case basis following an assessment of benefits vs risks of scanning in these situations.

  8. Reliability of a method to conduct upper airway analysis in cone-beam computed tomography

    Karen Regina Siqueira de Souza

    2013-02-01

    Full Text Available The aim of this study was to assess the reliability of a method to measure the following upper airway dimensions: total volume (TV, the nasopharyngeal narrowest areas (NNA, and the oropharyngeal narrowest areas (ONA. The sample consisted of 60 cone-beam computed tomography (CBCT scans, evaluated by two observers twice, using the Dolphin 3D software (Dolphin Imaging & Management solutions, Chatsworth, California, USA, which afforded image reconstruction, and measurement of the aforementioned dimensions. The data was submitted to reliability tests, by the intraclass correlation coefficient (ICC, and the Bland & Altman agreement tests, with their respective confidence intervals (CI set at 95%. Excellent intra- and interobserver reliability values were found for all variables assessed (TV, NNA and ONA, with ICC values ranging from 0.88 to 0.99. The data demonstrated an agreement between the two assessments of each observer and between the first evaluations of both observers, thus confirming the reliability of this methodology. The results suggest that this methodology can be used in further studies to investigate upper airway dimensions (TV, NNA, and ONA, thereby contributing to the diagnosis of upper airway obstructions.

  9. Volumetric analysis of the mandibular condyle using cone beam computed tomography

    Bayram, Mehmet, E-mail: dtmehmetbayram@yahoo.com [Karadeniz Technical University, Faculty of Dentistry, Department of Orthodontics, 61080 Trabzon (Turkey); Kayipmaz, Saadettin; Sezgin, Oemer Said [Karadeniz Technical University, Faculty of Dentistry, Department of Oral Radiology, Trabzon (Turkey); Kuecuek, Murat [Karadeniz Technical University, Faculty of Arts and Sciences, Department of Chemistry, Trabzon (Turkey)

    2012-08-15

    Objective: The aim was to determine the accuracy of volumetric analysis of the mandibular condyle using cone-beam computed tomography (CBCT). Materials and methods: Five dry mandibles containing 9 condyles were used. CBCT scans of the mandibles and an impression of each condylar area were taken. The physical volumes of the condyles were calculated as the gold standard using the water displacement technique. After isolating, the condylar volume was sectioned in the sagittal plane, and 0.3 mm thick sections with 0.9 mm intervals were obtained from 3D reconstructions. Using the Cavalieri principle, the volume of each condyle was estimated from the CBCT images by three observers. The accuracy of the CBCT volume measurements and the relation agreements between the results of the three observers were assessed using the Wilcoxon Signed Rank test and Pearson correlation test. The level of statistical significance was set at 0.05. Results: The results of the Pearson correlation showed that there were highly significant positive correlations between the observers' measurements. According to the results of the Wilcoxon Signed Rank test comparing the physical and observers' measurements, there were no statistically significant differences (p > 0.05). Conclusion: The Cavalieri principle, used in conjunction with a planimetry method, is a valid and effective method for volume estimation of the mandibular condyle on CBCT images.

  10. Quantitative Assessment of Cervical Vertebral Maturation Using Cone Beam Computed Tomography in Korean Girls

    Bo-Ram Byun

    2015-01-01

    Full Text Available This study was aimed to examine the correlation between skeletal maturation status and parameters from the odontoid process/body of the second vertebra and the bodies of third and fourth cervical vertebrae and simultaneously build multiple regression models to be able to estimate skeletal maturation status in Korean girls. Hand-wrist radiographs and cone beam computed tomography (CBCT images were obtained from 74 Korean girls (6–18 years of age. CBCT-generated cervical vertebral maturation (CVM was used to demarcate the odontoid process and the body of the second cervical vertebra, based on the dentocentral synchondrosis. Correlation coefficient analysis and multiple linear regression analysis were used for each parameter of the cervical vertebrae (P<0.05. Forty-seven of 64 parameters from CBCT-generated CVM (independent variables exhibited statistically significant correlations (P<0.05. The multiple regression model with the greatest R2 had six parameters (PH2/W2, UW2/W2, (OH+AH2/LW2, UW3/LW3, D3, and H4/W4 as independent variables with a variance inflation factor (VIF of <2. CBCT-generated CVM was able to include parameters from the second cervical vertebral body and odontoid process, respectively, for the multiple regression models. This suggests that quantitative analysis might be used to estimate skeletal maturation status.

  11. Bilateral and pseudobilateral tonsilloliths: Three dimensional imaging with cone-beam computed tomography

    Misirlioglu, Melda; Adisen, Mehmet Zahit; Yardimci, Selmi [Dept. of Oral and Maxillofacial Radiology, Faculty of Dentistry, Kirikkale University, Kirikkale (Turkmenistan); Nalcaci, Rana [Dept. of Oral and Maxillofacial Radiology, Faculty of Dentistry, Ankara University, Ankara (Turkmenistan)

    2013-09-15

    Tonsilloliths are calcifications found in the crypts of the palatal tonsils and can be detected on routine panoramic examinations. This study was performed to highlight the benefits of cone-beam computed tomography (CBCT) in the diagnosis of tonsilloliths appearing bilaterally on panoramic radiographs. The sample group consisted of 7 patients who had bilateral radiopaque lesions at the area of the ascending ramus on panoramic radiographs. CBCT images for every patient were obtained from both sides of the jaw to determine the exact locations of the lesions and to rule out other calcifications. The calcifications were evaluated on the CBCT images using Ez3D2009 software. Additionally, the obtained images in DICOM format were transferred to ITK SNAP 2.4.0 pc software for semiautomatic segmentation. Segmentation was performed using contrast differences between the soft tissues and calcifications on grayscale images, and the volume in mm{sup 3} of the segmented three dimensional models were obtained. CBCT scans revealed that what appeared on panoramic radiographs as bilateral images were in fact unilateral lesions in 2 cases. The total volume of the calcifications ranged from 7.92 to 302.5mm{sup 3}. The patients with bilaterally multiple and large calcifications were found to be symptomatic. The cases provided the evidence that tonsilloliths should be considered in the differential diagnosis of radiopaque masses involving the mandibular ramus, and they highlight the need for a CBCT scan to differentiate pseudo- or ghost images from true bilateral pathologies.

  12. Cone-beam computed tomography evaluation of Pont's index predictability for Malay population in orthodontics

    Alam, Mohammad Khursheed; Shahid, Fazal; Purmal, Kathiravan; Khamis, Mohd Fadhli

    2015-01-01

    Introduction: In orthodontic treatment, three-dimensional (3D) dental casts has a significant role in diagnosis and treatment planning. The aim of this study was to evaluate Pont's index predictability in orthodontics. Materials and Methods: Premolar arch width, molar arch width and mesiodistal width of the maxillary incisors were measured three-dimensionally to assess shape of dental arches. The data source was cone beam computed tomography (CBCT) high volumetric data acquisitions from Malay ethnic background. Arch widths were measured and recorded from 53 subjects (32 male and 21 female with the mean age, 25.81), both the maxillary and mandibular arches, to obtain CBCT high volumetric data. All measurements were obtained through CBCT Planmeca Romexis TM Software 2.3.1.R (Helsinki, Finland). Results: Pont's formula overestimated the upper and lower interpremolar distance, with mean differences of 8.35 ± 3 mm and 12.02 ± 3.20 mm, respectively. Furthermore, the formula overestimated the upper and lower intermolar distance, with mean differences of 7.87 ± 3 mm and 16.14 ± 5.86 mm, respectively. Conclusions: The results indicate that Pont's index is not practical for use with the Malaysian population since the index overestimated interpremolar and intermolar widths. This raises questions whether the index is a true predictor of arch width measurements. PMID:26604597

  13. The current status of cone beam computed tomography imaging in orthodontics

    Kapila, S; Conley, R S; Harrell, W E

    2011-01-01

    Cone beam CT (CBCT) has become an increasingly important source of three dimensional (3D) volumetric data in clinical orthodontics since its introduction into dentistry in 1998. The purpose of this manuscript is to highlight the current understanding of, and evidence for, the clinical use of CBCT in orthodontics, and to review the findings to answer clinically relevant questions. Currently available information from studies using CBCT can be organized into five broad categories: 1, the assessment of CBCT technology; 2, its use in craniofacial morphometric analyses; 3, incidental and missed findings; 4, analysis of treatment outcomes; and 5, efficacy of CBCT in diagnosis and treatment planning. The findings in these topical areas are summarized, followed by current indications and protocols for the use of CBCT in specific cases. Despite the increasing popularity of CBCT in orthodontics, and its advantages over routine radiography in specific cases, the effects of information derived from these images in altering diagnosis and treatment decisions has not been demonstrated in several types of cases. It has therefore been recommended that CBCT be used in select cases in which conventional radiography cannot supply satisfactory diagnostic information; these include cleft palate patients, assessment of unerupted tooth position, supernumerary teeth, identification of root resorption and for planning orthognathic surgery. The need to image other types of cases should be made on a case-by-case basis following an assessment of benefits vs risks of scanning in these situations. PMID:21159912

  14. Hardware-accelerated cone-beam reconstruction on a mobile C-arm

    Churchill, Michael; Pope, Gordon; Penman, Jeffrey; Riabkov, Dmitry; Xue, Xinwei; Cheryauka, Arvi

    2007-03-01

    The three-dimensional image reconstruction process used in interventional CT imaging is computationally demanding. Implementation on general-purpose computational platforms requires a substantial time, which is undesirable during time-critical surgical and minimally invasive procedures. Field Programmable Gate Arrays (FPGA)s and Graphics Processing Units (GPU)s have been studied as a platform to accelerate 3-D imaging. FPGA and GPU devices offer a reprogrammable hardware architecture, configurable for pipelining and high levels of parallel processing to increase computational throughput, as well as the benefits of being off-the-shelf and effective 'performance-to-watt' solutions. The main focus of this paper is on the backprojection step of the image reconstruction process, since it is the most computationally intensive part. Using the popular Feldkamp-Davis-Kress (FDK) cone-beam algorithm, our studies indicate the entire 256 3 image reconstruction process can be accelerated to real or near real-time (i.e. immediately after a finished scan of 15-30 seconds duration) on a mobile X-ray C-arm system using available resources on built-in FPGA board. High resolution 512 3 image backprojection can be also accomplished within the same scanning time on a high-end GPU board comprising up to 128 streaming processors.

  15. Implementation of the FDK algorithm for cone-beam CT on the cell broadband engine architecture

    Scherl, Holger; Koerner, Mario; Hofmann, Hannes; Eckert, Wieland; Kowarschik, Markus; Hornegger, Joachim

    2007-03-01

    In most of today's commercially available cone-beam CT scanners, the well known FDK method is used for solving the 3D reconstruction task. The computational complexity of this algorithm prohibits its use for many medical applications without hardware acceleration. The brand-new Cell Broadband Engine Architecture (CBEA) with its high level of parallelism is a cost-efficient processor for performing the FDK reconstruction according to the medical requirements. The programming scheme, however, is quite different to any standard personal computer hardware. In this paper, we present an innovative implementation of the most time-consuming parts of the FDK algorithm: filtering and back-projection. We also explain the required transformations to parallelize the algorithm for the CBEA. Our software framework allows to compute the filtering and back-projection in parallel, making it possible to do an on-the-fly-reconstruction. The achieved results demonstrate that a complete FDK reconstruction is computed with the CBEA in less than seven seconds for a standard clinical scenario. Given the fact that scan times are usually much higher, we conclude that reconstruction is finished right after the end of data acquisition. This enables us to present the reconstructed volume to the physician in real-time, immediately after the last projection image has been acquired by the scanning device.

  16. Quantitative analysis of periapical lesions on cone beam computed tomograph and periapical radiograph

    Kim, Jin Hoa; Lee, Wan; Kim, Kyung Soo; Roh, Young Chea; Lee, Byung Do [Department of Oral and Maxillofacial Radiology, School of Dentistry, Wonkwang University, Iksan (Korea, Republic of); Kim, De Sok [Department of Electrical Engineering, Korea Advanced Institute of Science and Technology, Deajeon (Korea, Republic of)

    2009-03-15

    To detect the progression of experimentally induced periapical lesions on periapical radiograph and cone beam computed tomograph (CBCT) by quantitative analysis. After the removal of coronal pulps from premolars of two Beagle dogs, the root canals of premolars were exposed to oral environment during one week and then sealed for 70 days. Digital periapical radiographs and CBCTs were taken at baseline and every 7 days for 77 days after pulp exposure. We examined occurrence and areas of periapical bone resorption. Three comparative groups of CBCT radiographs were prepared by average projection of thin slabs with different bucco-lingual thicknesses (0.1, 3.0, and 8.0 mm) using a 3D visualization software. Radiographic densities were compensated by image normalization. Digital images were processed with mathematical morphology operations. The radiographic density and morphological features of periapical lesions were compared among three groups of CBCT in different time points. In the CBCT group with 0.1 mm thickness, radiographic density (p<0.05) and trabecular bone area (p<0.01) were significantly decreased at the fifth week. However, in the CBCT groups with 3 mm and 8 mm thickness and periapical radiographs, none of densitometric and morphological features showed any significant differences in different time points. Radiographic density of periapical lesion showed increasing tendency at the eleventh week after pulp exposure. Radiographic detection of periapical lesions was possible at the fifth week after pulp contamination by quantitative method and was affected by buccolingual bone thickness.

  17. Cone-beam micro-CT system based on LabVIEW software.

    Ionita, Ciprian N; Hoffmann, Keneth R; Bednarek, Daniel R; Chityala, Ravishankar; Rudin, Stephen

    2008-09-01

    Construction of a cone-beam computed tomography (CBCT) system for laboratory research usually requires integration of different software and hardware components. As a result, building and operating such a complex system require the expertise of researchers with significantly different backgrounds. Additionally, writing flexible code to control the hardware components of a CBCT system combined with designing a friendly graphical user interface (GUI) can be cumbersome and time consuming. An intuitive and flexible program structure, as well as the program GUI for CBCT acquisition, is presented in this note. The program was developed in National Instrument's Laboratory Virtual Instrumentation Engineering Workbench (LabVIEW) graphical language and is designed to control a custom-built CBCT system but has been also used in a standard angiographic suite. The hardware components are commercially available to researchers and are in general provided with software drivers which are LabVIEW compatible. The program structure was designed as a sequential chain. Each step in the chain takes care of one or two hardware commands at a time; the execution of the sequence can be modified according to the CBCT system design. We have scanned and reconstructed over 200 specimens using this interface and present three examples which cover different areas of interest encountered in laboratory research. The resulting 3D data are rendered using a commercial workstation. The program described in this paper is available for use or improvement by other researchers.

  18. Cone-beam local reconstruction based on a Radon inversion transformation

    Wang Xian-Chao; Yan Bin; Li Lei; Hu Guo-En

    2012-01-01

    The local reconstruction from truncated projection data is one area of interest in image reconstruction for computed tomography (CT),which creates the possibility for dose reduction.In this paper,a filtered-backprojection (FBP)algorithm based on the Radon inversion transform is presented to deal with the three-dimensional (3D) local reconstruction in the circular geometry.The algorithm achieves the data filtering in two steps.The first step is the derivative of projections,which acts locally on the data and can thus be carried out accurately even in the presence of data truncation.The second step is the nonlocal Hilbert filtering.The numerical simulations and the real data reconstructions have been conducted to validate the new reconstruction algorithm.Compared with the approximate truncation resistant algorithm for computed tomography (ATRACT),not only it has a comparable ability to restrain truncation artifacts,but also its reconstruction efficiency is improved.It is about twice as fast as that of the ATRACT.Therefore,this work provides a simple and efficient approach for the approximate reconstruction from truncated projections in the circular cone-beam CT.

  19. A Comparison of the Amounts of Artifacts Produced by Five Cements in Cone-Beam CT

    Moshfeghi

    2016-02-01

    Full Text Available Background Bidimensional radiographic methods, including periapical, occlusal, panoramic, and cephalometric radiographs, are widely used in dentistry. However, the superimposition of adjacent structures and consequent loss of anatomic details may occur. Objectives The purpose of this study is to evaluate the artifacts produced by different cements with different densities using cone-beam computed tomography (CBCT. Materials and Methods Samples of five cements with different densities including glass ionomers (or GI, from ChemFil Rock and Fuji IX, mineral trioxide aggregates (MTA, zinc oxide eugenol (ZOE, TempBond and a control sample (polyester were scanned by CBCT device and analyzed using OnDemand 3D application software. The amount of artifacts was measured by ∆ gray scale value (∆GSV, which was achieved by subtracting the gray level of the samples from the control group. Results According to the mean GSV of the five different materials, the majority of artifacts produced were as follows: TempBond > ZOE > MTA > GI (ChemFil Dentsply > GI (GC, Fuji ΙX. Conclusions The type of materials can influence the obtained GSV. Different materials cause various amounts of artifacts due to differences in density and atomic number.

  20. Validating cone-beam computed tomography for peri-implant bone morphometric analysis

    Yan Huang; Jeroen Van Dessel; Maarten Depypere; Mostafa EzEldeen; Alexandru Andrei Iliescu; Emanuela Dos Santos; Ivo Lambrichts; Xin Liang; Reinhilde Jacobs

    2014-01-01

    Cone-beam computed tomography (CBCT) has been recently used to analyse trabecular bone structure around dental implants. To validate the use of CBCT for three-dimensional (3D) peri-implant trabecular bone morphometry by comparing it to two-dimensional (2D) histology, 36 alveolar bone samples (with implants n527 vs. without implants n59) from six mongrel dogs, were scanned ex vivo using a high-resolution (80 mm) CBCT. After scanning, all samples were decalcified and then sectioned into thin histological sections (,6 mm) to obtain high contrast 2D images. By using CTAn imaging software, bone morphometric parameters including trabecular number (Tb.N), thickness (Tb.Th), separation (Tb.Sp) and bone volume fraction (BV/TV) were examined on both CBCT and corresponding histological images. Higher Tb.Th and Tb.Sp, lower BV/TV and Tb.N were found on CBCT images (P,0.001). Both measurements on the peri-implant trabecular bone structure showed moderate to high correlation (r50.65-0.85). The Bland-Altman plots showed strongest agreement for Tb.Th followed by Tb.Sp, Tb.N and BV/TV, regardless of the presence of implants. The current findings support the assumption that peri-implant trabecular bone structures based on high-resolution CBCT measurements are representative for the underlying histological bone characteristics, indicating a potential clinical diagnostic use of CBCT-based peri-implant bone morphometric characterisation.

  1. Segmentation of cone-beam CT using a hidden Markov random field with informative priors

    Moores, M.; Hargrave, C.; Harden, F.; Mengersen, K.

    2014-03-01

    Cone-beam computed tomography (CBCT) has enormous potential to improve the accuracy of treatment delivery in image-guided radiotherapy (IGRT). To assist radiotherapists in interpreting these images, we use a Bayesian statistical model to label each voxel according to its tissue type. The rich sources of prior information in IGRT are incorporated into a hidden Markov random field model of the 3D image lattice. Tissue densities in the reference CT scan are estimated using inverse regression and then rescaled to approximate the corresponding CBCT intensity values. The treatment planning contours are combined with published studies of physiological variability to produce a spatial prior distribution for changes in the size, shape and position of the tumour volume and organs at risk. The voxel labels are estimated using iterated conditional modes. The accuracy of the method has been evaluated using 27 CBCT scans of an electron density phantom. The mean voxel-wise misclassification rate was 6.2%, with Dice similarity coefficient of 0.73 for liver, muscle, breast and adipose tissue. By incorporating prior information, we are able to successfully segment CBCT images. This could be a viable approach for automated, online image analysis in radiotherapy.

  2. A comparative evaluation of Cone Beam Computed Tomography (CBCT) and Multi-Slice CT (MSCT)

    Liang Xin, E-mail: Xin.Liang@med.kuleuven.b [Oral Imaging Centre, School of Dentistry, Oral Pathology and Maxillofacial Surgery, Faculty of Medicine, Catholic University of Leuven (Belgium); College of Stomatology, Dalian Medical University (China); Jacobs, Reinhilde, E-mail: Reinhilde.Jacobs@uz.kuleuven.b [Oral Imaging Centre, School of Dentistry, Oral Pathology and Maxillofacial Surgery, Faculty of Medicine, Catholic University of Leuven (Belgium); Hassan, Bassam, E-mail: b.hassan@acta.n [Department of Oral Radiology, Academic Centre for Dentistry Amsterdam (ACTA), Amsterdam (Netherlands); Li Limin, E-mail: Limin.Li@uz.kuleuven.b [Department of Paediatric Dentistry and Special Dental Care, School of Dentistry, Oral Pathology and Maxillofacial Surgery, Faculty of Medicine, Catholic University of Leuven (Belgium); Pauwels, Ruben, E-mail: Ruben.Pauwels@med.kuleuven.b [Oral Imaging Centre, School of Dentistry, Oral Pathology and Maxillofacial Surgery, Faculty of Medicine, Catholic University of Leuven (Belgium); Corpas, Livia, E-mail: LiviaCorpas@gmail.co [Oral Imaging Centre, School of Dentistry, Oral Pathology and Maxillofacial Surgery, Faculty of Medicine, Catholic University of Leuven (Belgium); Souza, Paulo Couto, E-mail: Paulo.CoutoSouza@med.kuleuven.b [Oral Imaging Centre, School of Dentistry, Oral Pathology and Maxillofacial Surgery, Faculty of Medicine, Catholic University of Leuven (Belgium); Martens, Wendy, E-mail: wendy.martens@uhasselt.b [Department of Basic Medical Sciences, Faculty of Medicine, University of Hasselt, Diepenbeek (Belgium); Shahbazian, Maryam, E-mail: Maryam.Shahbazian@student.kuleuven.b [Oral Imaging Centre, School of Dentistry, Oral Pathology and Maxillofacial Surgery, Faculty of Medicine, Catholic University of Leuven (Belgium); Alonso, Arie, E-mail: ariel.alonso@uhasselt.b [Department of Biostatistics and Statistical Bioinformatics, Universiteit Hasselt (Belgium)

    2010-08-15

    Aims: 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. Materials and methods: 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. Results: 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. Conclusions: 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.

  3. A study on mechanical errors in Cone Beam Computed Tomography (CBCT) System

    Lee, Yi Seong; Yoo, Eun Jeong; Choi, Kyoung Sik [Dept. of Radiation Oncology, Anyang SAM Hospital, Anyang (Korea, Republic of); Lee, Jong Woo [Dept. of Radiation Oncology, Konkuk University Medical Center, Seoul (Korea, Republic of); Suh, Tae Suk [Dept. of Biomedical Engineering and Research Institute of Biomedical Engineering, College of Medicine, The Catholic University of Korea, Seoul (Korea, Republic of); Kim, Jeong Koo [Dept. of Radiological Science, Hanseo University, Seosan (Korea, Republic of)

    2013-06-15

    This study investigated the rate of setup variance by the rotating unbalance of gantry in image-guided radiation therapy. The equipments used linear accelerator(Elekta Synergy ™, UK) and a three-dimensional volume imaging mode(3D Volume View) in cone beam computed tomography(CBCT) system. 2D images obtained by rotating 360°and 180° were reconstructed to 3D image. Catpan503 phantom and homogeneous phantom were used to measure the setup errors. Ball-bearing phantom was used to check the rotation axis of the CBCT. The volume image from CBCT using Catphan503 phantom and homogeneous phantom were analyzed and compared to images from conventional CT in the six dimensional view(X, Y, Z, Roll, Pitch, and Yaw). The variance ratio of setup error were difference in X 0.6 mm, Y 0.5 mm, Z 0.5 mm when the gantry rotated 360° in orthogonal coordinate. whereas rotated 180°, the error measured 0.9 mm, 0.2 mm, 0.3 mm in X, Y, Z respectively. In the rotating coordinates, the more increased the rotating unbalance, the more raised average ratio of setup errors. The resolution of CBCT images showed 2 level of difference in the table recommended. CBCT had a good agreement compared to each recommended values which is the mechanical safety, geometry accuracy and image quality. The rotating unbalance of gentry vary hardly in orthogonal coordinate. However, in rotating coordinate of gantry exceeded the ±1° of recommended value. Therefore, when we do sophisticated radiation therapy six dimensional correction is needed.

  4. Vertical bone measurements from cone beam computed tomography images using different software packages

    Vasconcelos, Taruska Ventorini; Neves, Frederico Sampaio; Moraes, Livia Almeida Bueno; Freitas, Deborah Queiroz, E-mail: tataventorini@hotmail.com [Universidade Estadual de Campinas (UNICAMP), Piracicaba, SP (Brazil). Faculdade de Odontologia

    2015-03-01

    This article aimed at comparing the accuracy of linear measurement tools of different commercial software packages. Eight fully edentulous dry mandibles were selected for this study. Incisor, canine, premolar, first molar and second molar regions were selected. Cone beam computed tomography (CBCT) images were obtained with i-CAT Next Generation. Linear bone measurements were performed by one observer on the cross-sectional images using three different software packages: XoranCat®, OnDemand3D® and KDIS3D®, all able to assess DICOM images. In addition, 25% of the sample was reevaluated for the purpose of reproducibility. The mandibles were sectioned to obtain the gold standard for each region. Intraclass coefficients (ICC) were calculated to examine the agreement between the two periods of evaluation; the one-way analysis of variance performed with the post-hoc Dunnett test was used to compare each of the software-derived measurements with the gold standard. The ICC values were excellent for all software packages. The least difference between the software-derived measurements and the gold standard was obtained with the OnDemand3D and KDIS3D (‑0.11 and ‑0.14 mm, respectively), and the greatest, with the XoranCAT (+0.25 mm). However, there was no statistical significant difference between the measurements obtained with the different software packages and the gold standard (p > 0.05). In conclusion, linear bone measurements were not influenced by the software package used to reconstruct the image from CBCT DICOM data. (author)

  5. Iodized oil uptake assessment with cone-beam CT in chemoembolization of small hepatocellular carcinomas

    Ung Bae Jeon; Jun Woo Lee; Ki Seok Choo; Chang Won Kim; Suk Kim; Tae Hong Lee; Yeon Joo Jeong; Dae Hwan Kang

    2009-01-01

    AIM: To evaluate the utility of assessing iodized oil uptake with cone-beam computed tomography (CT) in transarterial chemoembolization (TACE) for small hepatocellular carcinoma (HCC). METHODS: Cone-beam CT provided by a biplane flatpanel detector angiography suite was performed on eighteen patients (sixteen men and two women; 41-76 years; mean age, 58.9 years) directly after TACE for small HCC (26 nodules under 30 mm; mean diameter, 11.9 mm; range, 5-28 mm). The pre-procedural locations of the tumors were evaluated using triphasic multi-detector row helical computed tomography (MDCT). The tumor locations on MDCT and the iodized oil uptake by the tumors were analyzed on cone-beam CT and on spot image directly after the procedures. RESULTS: All lesions on preprocedural MDCT were detected using iodized oil uptake in the lesions on conebeam CT (sensitivity 100%, 26/26). Spot image depicted iodized oil uptake in 22 of the lesions (sensitivity 85%). The degree of iodized oil uptake was overestimated (9%, 2/22) or underestimated (14%, 3/22) on spot image in five nodules compared with that of cone-beam CT. CONCLUSION: Cone-beam CT is a useful and convenient tool for assessing the iodized oil uptake of small hepatic tumors (< 3 cm) directly after TACE.

  6. A three-dimensional weighted cone beam filtered backprojection (CB-FBP) algorithm for image reconstruction in volumetric CT under a circular source trajectory

    Tang, Xiangyang; Hsieh, Jiang; Hagiwara, Akira; Nilsen, Roy A.; Thibault, Jean-Baptiste; Drapkin, Evgeny

    2005-08-01

    The original FDK algorithm proposed for cone beam (CB) image reconstruction under a circular source trajectory has been extensively employed in medical and industrial imaging applications. With increasing cone angle, CB artefacts in images reconstructed by the original FDK algorithm deteriorate, since the circular trajectory does not satisfy the so-called data sufficiency condition (DSC). A few 'circular plus' trajectories have been proposed in the past to help the original FDK algorithm to reduce CB artefacts by meeting the DSC. However, the circular trajectory has distinct advantages over other scanning trajectories in practical CT imaging, such as head imaging, breast imaging, cardiac, vascular and perfusion applications. In addition to looking into the DSC, another insight into the CB artefacts existing in the original FDK algorithm is the inconsistency between conjugate rays that are 180° apart in view angle (namely conjugate ray inconsistency). The conjugate ray inconsistency is pixel dependent, varying dramatically over pixels within the image plane to be reconstructed. However, the original FDK algorithm treats all conjugate rays equally, resulting in CB artefacts that can be avoided if appropriate weighting strategies are exercised. Along with an experimental evaluation and verification, a three-dimensional (3D) weighted axial cone beam filtered backprojection (CB-FBP) algorithm is proposed in this paper for image reconstruction in volumetric CT under a circular source trajectory. Without extra trajectories supplemental to the circular trajectory, the proposed algorithm applies 3D weighting on projection data before 3D backprojection to reduce conjugate ray inconsistency by suppressing the contribution from one of the conjugate rays with a larger cone angle. Furthermore, the 3D weighting is dependent on the distance between the reconstruction plane and the central plane determined by the circular trajectory. The proposed 3D weighted axial CB-FBP algorithm

  7. Application of cone beam computed tomography in facial imaging science

    Fourie, Zacharias; Damstra, Janalt; Ren, Yijin

    2012-01-01

    The use of three-dimensional (3D) methods for facial imaging has increased significantly over the past years. Traditional 2D imaging has gradually being replaced by 3D images in different disciplines, particularly in the fields of orthodontics, maxillofacial surgery, plastic and reconstructive surge

  8. Dynamics of 3D Timoshenko gyroelastic beams with large attitude changes for the gyros

    Hassanpour, Soroosh; Heppler, G. R.

    2016-01-01

    This work is concerned with the theoretical development of dynamic equations for undamped gyroelastic beams which are dynamic systems with continuous inertia, elasticity, and gyricity. Assuming unrestricted or large attitude changes for the axes of the gyros and utilizing generalized Hooke's law, Duleau torsion theory, and Timoshenko bending theory, the energy expressions and equations of motion for the gyroelastic beams in three-dimensional space are derived. The so-obtained comprehensive gyroelastic beam model is compared against earlier gyroelastic beam models developed using Euler-Bernoulli beam models and is used to study the dynamics of gyroelastic beams through numerical examples. It is shown that there are significant differences between the developed unrestricted Timoshenko gyroelastic beam model and the previously derived zero-order restricted Euler-Bernoulli gyroelastic beam models. These differences are more pronounced in the short beam and transverse gyricity cases.

  9. Quantitative cone beam X-ray luminescence tomography/X-ray computed tomography imaging

    Chen, Dongmei; Zhu, Shouping, E-mail: zhusp2009@gmail.com; Chen, Xueli; Chao, Tiantian; Cao, Xu; Zhao, Fengjun; Huang, Liyu; Liang, Jimin [Engineering Research Center of Molecular and Neuro Imaging of Ministry of Education and School of Life Science and Technology, Xidian University, Xi' an, Shaanxi 710071 (China)

    2014-11-10

    X-ray luminescence tomography (XLT) is an imaging technology based on X-ray-excitable materials. The main purpose of this paper is to obtain quantitative luminescence concentration using the structural information of the X-ray computed tomography (XCT) in the hybrid cone beam XLT/XCT system. A multi-wavelength luminescence cone beam XLT method with the structural a priori information is presented to relieve the severe ill-posedness problem in the cone beam XLT. The nanophosphors and phantom experiments were undertaken to access the linear relationship of the system response. Then, an in vivo mouse experiment was conducted. The in vivo experimental results show that the recovered concentration error as low as 6.67% with the location error of 0.85 mm can be achieved. The results demonstrate that the proposed method can accurately recover the nanophosphor inclusion and realize the quantitative imaging.

  10. Cone Beam CT在牙种植术中应用的临床观察

    李蓓

    2009-01-01

    文章通过对64例拟行牙种植术患者进行Cone Beam CT检查,观察CT影像在牙种植手术适应证评价与手术设计中的作用.与X线曲面断层片及模型观测结果相比,Cone Beam CT影像提供了更直观,更精确的种植区骨条件信息,提高了牙种植手术的效率,牙种植手术无1例失败.Cone Beam CT应用于牙种植术,能够使手术更加安全、高效,具有较高的临床应用价值.

  11. Comparison of flat-panel detector and image-intensifier detector for cone-beam CT.

    Baba, Rika; Konno, Yasutaka; Ueda, Ken; Ikeda, Shigeyuki

    2002-01-01

    We evaluated a flat-panel detector (FPD) (scintillator screen and a-Si photo-sensor array) for use in a cone-beam computed tomography (CT) detector and compared it with an image-intensifier detector (IID). The FPD cone-beam CT system has a higher spatial resolution than the IID system. At equal pixel sizes, the standard deviation of noise intensity of the FPD system is equal to that of the IID system. However, the circuit noise of the FPD must be reduced, especially at low doses. Our evaluations show that the FPD system has a strong potential for use as a cone-beam CT detector because of high-spatial resolution.

  12. Cone beam CT findings of retromolar canals: Report of cases and literature review

    Han, Sang Sun [Dept. of Dental Hygiene, Eulji University, Seongnam (Korea, Republic of); Park, Chang Seo [Dept. of Oral and Maxillofacial Radiology, College of Dentistry, Yonsei University, Seoul (Korea, Republic of)

    2013-12-15

    A retromolar canal is an anatomical variation in the mandible. As it includes the neurovascular bundle, local anesthetic insufficiency can occur, and an injury of the retromolar canal during dental surgery in the mandible may result in excessive bleeding, paresthesia, and traumatic neuroma. Using imaging analysis software, we evaluated the cone-beam computed tomography (CT) images of two Korean patients who presented with retromolar canals. Retromolar canals were detectable on the sagittal and cross-sectional images of cone-beam CT, but not on the panoramic radiographs of the patients. Therefore, the clinician should pay particular attention to the identification of retromolar canals by preoperative radiographic examination, and additional cone beam CT scanning would be recommended.

  13. Tetrahedron-based orthogonal simultaneous scan for cone-beam computed tomography.

    Ye, Ivan B; Wang, Ge

    2012-08-01

    In this article, a cone-beam computed tomography scanning mode is designed using four x-ray sources and a spherical sample. The x-ray sources are mounted at the vertices of a regular tetrahedron. On the circumsphere of the tetrahedron, four detection panels are mounted opposite of each vertex. To avoid x-ray interference, the largest half angle of each x-ray cone beam is 27°22', while the radius of the largest ball fully covered by all the cone beams is 0.460, when the radius of the circumsphere is 1. A proposed scanning scheme consists of two rotations about orthogonal axes, such that, each quarter turn provides sufficient data for theoretically exact and stable reconstruction. This design can be used in biomedical or industrial settings, such as when a sequence of reconstructions of an object is desired.

  14. Focussed ion beam nanotomography reveals the 3D morphology of different solid phases in hardened cement pastes.

    Trtik, P; Münch, B; Gasser, P; Leemann, A; Loser, R; Wepf, R; Lura, P

    2011-03-01

    Due to the development of integrated low-keV back-scattered electron detectors, it has become possible in focussed ion beam nanotomography to segment not only solid matter and porosity of hardened cement paste, but also to distinguish different phases within the solid matter. This paper illustrates a method that combines two different approaches for improving the contrast between different phases in the solid matrix of a cement paste. The first approach is based on the application of a specially developed 3D diffusion filter. The second approach is based on a modified data-acquisition procedure during focussed ion beam nanotomography. A pair of electron images is acquired for each slice in the focussed ion beam nanotomography dataset. The first image is captured immediately after ion beam milling; the second image is taken after a prolonged exposure to electron beam scanning. The acquisition of complementary focussed ion beam nanotomography datasets and processing the images with a 3D anisotropic diffusion filter allows distinguishing different phases within the hydration products.

  15. Dosimetric characterization and application of an imaging beam line with a carbon electron target for megavoltage cone beam computed tomography.

    Flynn, Ryan T; Hartmann, Julia; Bani-Hashemi, Ali; Nixon, Earl; Alfredo, R; Siochi, C; Pennington, Edward C; Bayouth, John E

    2009-06-01

    Imaging dose from megavoltage cone beam computed tomography (MVCBCT) can be significantly reduced without loss of image quality by using an imaging beam line (IBL), with no flattening filter and a carbon, rather than tungsten, electron target. The IBL produces a greater keV-range x-ray fluence than the treatment beam line (TBL), which results in a more optimal detector response. The IBL imaging dose is not necessarily negligible, however. In this work an IBL was dosimetrically modeled with the Philips Pinnacle3 treatment planning system (TPS), verified experimentally, and applied to clinical cases. The IBL acquisition dose for a 200 degrees gantry rotation was verified in a customized acrylic cylindrical phantom at multiple imaging field sizes with 196 ion chamber measurements. Agreement between the measured and calculated IBL dose was quantified with the 3D gamma index. Representative IBL and TBL imaging dose distributions were calculated for head and neck and prostate patients and included in treatment plans using the imaging dose incorporation (IDI) method. Surface dose was measured for the TBL and IBL for four head and neck cancer patients with MOSFETs. The IBL model, when compared to the percentage depth dose and profile measurements, had 97% passing gamma indices for dosimetric and distance acceptance criteria of 3%, 3 mm, and 100% passed for 5.2%, 5.2 mm. For the ion chamber measurements of phantom image acquisition dose, the IBL model had 93% passing gamma indices for acceptance criteria of 3%, 3 mm, and 100% passed for 4%, 4 mm. Differences between the IBL- and TBL-based IMRT treatment plans created with the IDI method were dosimetrically insignificant for both the prostate and head and neck cases. For IBL and TBL beams with monitor unit values that would result in the delivery of the same dose to the depth of maximum dose under standard calibration conditions, the IBL imaging surface dose was higher than the TBL imaging surface dose by an average of 18

  16. Task-driven image acquisition and reconstruction in cone-beam CT.

    Gang, Grace J; Stayman, J Webster; Ehtiati, Tina; Siewerdsen, Jeffrey H

    2015-04-21

    This work introduces a task-driven imaging framework that incorporates a mathematical definition of the imaging task, a model of the imaging system, and a patient-specific anatomical model to prospectively design image acquisition and reconstruction techniques to optimize task performance. The framework is applied to joint optimization of tube current modulation, view-dependent reconstruction kernel, and orbital tilt in cone-beam CT. The system model considers a cone-beam CT system incorporating a flat-panel detector and 3D filtered backprojection and accurately describes the spatially varying noise and resolution over a wide range of imaging parameters in the presence of a realistic anatomical model. Task-based detectability index (d') is incorporated as the objective function in a task-driven optimization of image acquisition and reconstruction techniques. The orbital tilt was optimized through an exhaustive search across tilt angles ranging ± 30°. For each tilt angle, the view-dependent tube current and reconstruction kernel (i.e. the modulation profiles) that maximized detectability were identified via an alternating optimization. The task-driven approach was compared with conventional unmodulated and automatic exposure control (AEC) strategies for a variety of imaging tasks and anthropomorphic phantoms. The task-driven strategy outperformed the unmodulated and AEC cases for all tasks. For example, d' for a sphere detection task in a head phantom was improved by 30% compared to the unmodulated case by using smoother kernels for noisy views and distributing mAs across less noisy views (at fixed total mAs) in a manner that was beneficial to task performance. Similarly for detection of a line-pair pattern, the task-driven approach increased d' by 80% compared to no modulation by means of view-dependent mA and kernel selection that yields modulation transfer function and noise-power spectrum optimal to the task. Optimization of orbital tilt identified the tilt

  17. Three-dimensional reconstruction from cone-beam data using an efficient Fourier technique combined with a special interpolation filter.

    Seger, M M

    1998-04-01

    We here present LINCON(FAST) which is an exact method for 3D reconstruction from cone-beam projection data. The new method is compared to the LINCON method which is known to be fast and to give good image quality. Both methods have O(N3 log N) complexity and are based on Grangeat's result which states that the derivative of the Radon transform of the object function can be obtained from cone-beam projections. One disadvantage with LINCON is that the rather computationally intensive chirp z-transform is frequently used. In LINCON(FAST), FFT and interpolation in the Fourier domain are used instead, which are less computationally demanding. The computation tools involved in LINCON(FAST) are solely FFT, 1D eight-point interpolation, multiplicative weighting and tri-linear interpolation. We estimate that LINCON(FAST) will be 2-2.5 times faster than LINCON. The interpolation filter belongs to a special class of filters developed by us. It turns out that the filter must be very carefully designed to keep a good image quality. Visual inspection of experimental results shows that the image quality is almost the same for LINCON and the new method LINCON(FAST). However, it should be remembered that LINCON(FAST) can never give better image quality than LINCON, since LINCON(FAST) is designed to approximate LINCON as well as possible.

  18. Three-dimensional reconstruction from cone-beam data using an efficient Fourier technique combined with a special interpolation filter

    Magnusson Seger, Maria [Image Processing Laboratory, Department of Electrical Engineering, Linkoeping University, S-581 83 Linkoeping (Sweden)

    1998-04-01

    We here present LINCON{sub FAST} which is an exact method for 3D reconstruction from cone-beam projection data. The new method is compared to the LINCON method which is known to be fast and to give good image quality. Both methods have O(N{sup 3} log N) complexity and are based on Grangeat's result which states that the derivative of the Radon transform of the object function can be obtained from cone-beam projections. One disadvantage with LINCON is that the rather computationally intensive chirp z-transform is frequently used. In LINCON{sub FAST}, FFT and interpolation in the Fourier domain are used instead, which are less computationally demanding. The computation tools involved in LINCON{sub FAST} are solely FFT, 1D eight-point interpolation, multiplicative weighting and tri-linear interpolation. We estimate that LINCON{sub FAST} will be 2-2.5 times faster than LINCON. The interpolation filter belongs to a special class of filters developed by us. It turns out that the filter must be very carefully designed to keep a good image quality. Visual inspection of experimental results shows that the image quality is almost the same for LINCON and the new method LINCON{sub FAST}. However, it should be remembered that LINCON{sub FAST} can never give better image quality than LINCON, since LINCON{sub FAST} is designed to approximate LINCON as well as possible. (author)

  19. Protocol of image guided off-line using cone beam CT megavoltage; Protocolo de imagen guiada off-line mediante Cone Beam CT de megavoltaje

    Garcia Ruiz-Zorrilla, J.; Fernandez Leton, J. P.; Perez Moreno, J. M.; Zucca Aparicio, D.; Minambres Moro, A.

    2013-07-01

    The goal of image guided protocols offline is to reduce systematic errors in positioning of the patient in the treatment unit, being more important than the random errors, since the systematic have one contribution in the margin of the CTV to the PTV. This paper proposes a protocol for image guided offline with the different actions to take with their threshold values evaluated previously by anatomic location in a sample of 474 patients and 4821Cone beam Megavoltaje CT (CBCT). (Author)

  20. Exact and efficient cone-beam reconstruction algorithm for a short-scan circle combined with various lines

    Dennerlein, Frank; Katsevich, Alexander; Lauritsch, Guenter; Hornegger, Joachim

    2005-04-01

    X-ray 3D rotational angiography based on C-arm systems has become a versatile and established tomographic imaging modality for high contrast objects in interventional environment. Improvements in data acquisition, e.g. by use of flat panel detectors, will enable C-arm systems to resolve even low-contrast details. However, further progress will be limited by the incompleteness of data acquisition on the conventional short-scan circular source trajectories. Cone artifacts, which result from that incompleteness, significantly degrade image quality by severe smearing and shading. To assure data completeness a combination of a partial circle with one or several line segments is investigated. A new and efficient reconstruction algorithm is deduced from a general inversion formula based on 3D Radon theory. The method is theoretically exact, possesses shift-invariant filtered backprojection (FBP) structure, and solves the long object problem. The algorithm is flexible in dealing with various circle and line configurations. The reconstruction method requires nothing more than the theoretically minimum length of scan trajectory. It consists of a conventional short-scan circle and a line segment approximately twice as long as the height of the region-of-interest. Geometrical deviations from the ideal source trajectory are considered in the implementation in order to handle data of real C-arm systems. Reconstruction results show excellent image quality free of cone artifacts. The proposed scan trajectory and reconstruction algorithm assure excellent image quality and allow low-contrast tomographic imaging with C-arm based cone-beam systems. The method can be implemented without any hardware modifications on systems commercially available today.

  1. Static analysis of offshore risers with a geometrically-exact 3D beam model subjected to unilateral contact

    Neto, Alfredo Gay; Martins, Clóvis A.; Pimenta, Paulo M.

    2014-01-01

    In offshore applications there are elements that can be modeled as long beams, such as umbilical cables, flexible and rigid pipes and hoses, immersed in the sea water, suspended from the floating unit to the seabed. The suspended part of these elements is named "riser" and is subjected to the ocean environment loads, such as waves and sea current. This work presents a structural geometrically-exact 3D beam model, discretized using the finite element method for riser modeling. An updated Lagrangian framework for the rotation parameterization has been used for the description of the exact kinematics. The goal is to perform a complete static analysis, considering the oceanic loads and the unilateral contact with the seabed, extending the current standard analysis for situations in which very large rotations occurs, in particular, large torsion. Details of the nonlinear 3D model and loads from oceanic environment are discussed, including the contact unilateral constraint.

  2. Optical CT scanner for in-air readout of gels for external radiation beam 3D dosimetry.

    Ramm, Daniel; Rutten, Thomas P; Shepherd, Justin; Bezak, Eva

    2012-06-21

    Optical CT scanners for a 3D readout of externally irradiated radiosensitive hydrogels currently require the use of a refractive index (RI) matching liquid bath to obtain suitable optical ray paths through the gel sample to the detector. The requirement for a RI matching liquid bath has been negated by the design of a plastic cylindrical gel container that provides parallel beam geometry through the gel sample for the majority of the projection. The design method can be used for various hydrogels. Preliminary test results for the prototype laser beam scanner with ferrous xylenol-orange gel show geometric distortion of 0.2 mm maximum, spatial resolution limited to beam spot size of about 0.4 mm and 0.8% noise (1 SD) for a uniform irradiation. Reconstruction of a star pattern irradiated through the cylinder walls demonstrates the suitability for external beam applications. The extremely simple and cost-effective construction of this optical CT scanner, together with the simplicity of scanning gel samples without RI matching fluid increases the feasibility of using 3D gel dosimetry for clinical external beam dose verifications.

  3. Investigation of respiration induced intra- and inter-fractional tumour motion using a standard Cone Beam CT

    Gottlieb, Karina Lindberg; Hansen, Christian R; Hansen, Olfred;

    2010-01-01

    To investigate whether a standard Cone beam CT (CBCT) scan can be used to determined the intra- and inter-fractional tumour motion for lung tumours that have infiltrated the mediastinum.......To investigate whether a standard Cone beam CT (CBCT) scan can be used to determined the intra- and inter-fractional tumour motion for lung tumours that have infiltrated the mediastinum....

  4. Multimode C-arm fluoroscopy, tomosynthesis, and cone-beam CT for image-guided interventions: from proof of principle to patient protocols

    Siewerdsen, J. H.; Daly, M. J.; Bachar, G.; Moseley, D. J.; Bootsma, G.; Brock, K. K.; Ansell, S.; Wilson, G. A.; Chhabra, S.; Jaffray, D. A.; Irish, J. C.

    2007-03-01

    High-performance intraoperative imaging is essential to an ever-expanding scope of therapeutic procedures ranging from tumor surgery to interventional radiology. The need for precise visualization of bony and soft-tissue structures with minimal obstruction to the therapy setup presents challenges and opportunities in the development of novel imaging technologies specifically for image-guided procedures. Over the past ~5 years, a mobile C-arm has been modified in collaboration with Siemens Medical Solutions for 3D imaging. Based upon a Siemens PowerMobil, the device includes: a flat-panel detector (Varian PaxScan 4030CB); a motorized orbit; a system for geometric calibration; integration with real-time tracking and navigation (NDI Polaris); and a computer control system for multi-mode fluoroscopy, tomosynthesis, and cone-beam CT. Investigation of 3D imaging performance (noise-equivalent quanta), image quality (human observer studies), and image artifacts (scatter, truncation, and cone-beam artifacts) has driven the development of imaging techniques appropriate to a host of image-guided interventions. Multi-mode functionality presents a valuable spectrum of acquisition techniques: i.) fluoroscopy for real-time 2D guidance; ii.) limited-angle tomosynthesis for fast 3D imaging (e.g., ~10 sec acquisition of coronal slices containing the surgical target); and iii.) fully 3D cone-beam CT (e.g., ~30-60 sec acquisition providing bony and soft-tissue visualization across the field of view). Phantom and cadaver studies clearly indicate the potential for improved surgical performance - up to a factor of 2 increase in challenging surgical target excisions. The C-arm system is currently being deployed in patient protocols ranging from brachytherapy to chest, breast, spine, and head and neck surgery.

  5. Computer simulation of 2-D and 3-D ion beam extraction and acceleration

    Ido, Shunji; Nakajima, Yuji [Saitama Univ., Urawa (Japan). Faculty of Engineering

    1997-03-01

    The two-dimensional code and the three-dimensional code have been developed to study the physical features of the ion beams in the extraction and acceleration stages. By using the two-dimensional code, the design of first electrode(plasma grid) is examined in regard to the beam divergence. In the computational studies by using the three-dimensional code, the axis-off model of ion beam is investigated. It is found that the deflection angle of ion beam is proportional to the gap displacement of the electrodes. (author)

  6. The Relationships of the Maxillary Sinus With the Superior Alveolar Nerves and Vessels as Demonstrated by Cone-Beam CT Combined With μ-CT and Histological Analyses.

    Kasahara, Norio; Morita, Wataru; Tanaka, Ray; Hayashi, Takafumi; Kenmotsu, Shinichi; Ohshima, Hayato

    2016-05-01

    There are no available detailed data on the three-dimensional courses of the human superior alveolar nerves and vessels. This study aimed to clarify the relationships of the maxillary sinus with the superior alveolar nerves and vessels using cone-beam computed tomography (CT) combined with μ-CT and histological analyses. Digital imaging and communication in medicine data obtained from the scanned heads/maxillae of cadavers used for undergraduate/postgraduate dissection practice and skulls using cone-beam CT were reconstructed into three-dimensional (3D) images using software. The 3D images were compared with μ-CT images and histological sections. Cone-beam CT clarified the relationships of the maxillary sinus with the superior alveolar canals/grooves. The main anterior superior alveolar canal/groove ran anteriorly through the upper part of the sinus and terminated at the bottom of the nasal cavity near the piriform aperture. The main middle alveolar canal ran downward from the upper part of the sinus to ultimately join the anterior one. The main posterior alveolar canal ran through the lateral lower part of the sinus and communicated with the anterior one. Histological analyses demonstrated the existence of nerves and vessels in these canals/grooves, and the quantities of these structures varied across each canal/groove. Furthermore, the superior dental nerve plexus exhibited a network that was located horizontally to the occlusal plane, although these nerve plexuses appeared to be the vertical network that is described in most textbooks. In conclusion, cone-beam CT is suggested to be a useful method for clarifying the superior alveolar canals/grooves including the nerves and vessels.

  7. Ion-beam enhanced etching for the 3D structuration of lithium niobate; Ionenstrahlverstaerktes Aetzen fuer die 3D-Strukturierung von Lithiumniobat

    Gischkat, Thomas

    2010-01-12

    The present thesis deals with the usage of the ion-beam enhanced etching (IBEE) for the 3D structuration of lithium niobate (LiNbO{sub 3}).Hereby the approach of the enhancement of the wet-chemical etching rate due to the irradiation with energetic ions is pursued. This method is very success promising for the realization of micro- and nanostructures with perpendicular structural walls as well as small roughnesses. The aim of this thesis consisted therein to form the foundations for the realization of three-dimensional micro- and nanostructures (for instance: Layer systems and photonic crystals) in LiNbO{sub 3} with high optical quality and to demonstrate on selected examples. Conditions for the success of the IBEE structuration technique is first of all the understanding of the defect formation under ion irradiation as well as the radiation-induced structure changes in the crystal and the change of the chemical resistance connected with this. For this the defect formation was studied in dependence on th ion mass, the ion energy, and the irradiation temperature. Thermally induced influences and effects on the radiation damage, as they can occur in intermediate steps in the complex processing, must be known and were studied by means of subsequent temperature treatment. The results from the defect studies were subsequently applied for the fabrication of micro- and nanostructures in LiNbO{sub 3}. Shown is the realization of lateral structure with nearly perpendicular structure walls as well as the realization of thin membranes and slits. The subsequent combination of lateral structuration with the fabrication of thin membranes and slits allowed the three-dimensional structuration of LiNbO{sub 3}. This is exemplarily shown for a microresonator and for a 2D photonic crystal with below lying air slit. [German] Die vorliegende Arbeit beschaeftigt sich mit der Ausnutzung des ionenstrahlverstaerkten Aetzens (IBEE: Ion Beam Enhanced Etching) fuer die 3D-Strukturierung von

  8. Segmentation of large periapical lesions toward dental computer-aided diagnosis in cone-beam CT scans

    Rysavy, Steven; Flores, Arturo; Enciso, Reyes; Okada, Kazunori

    2008-03-01

    This paper presents an experimental study for assessing the applicability of general-purpose 3D segmentation algorithms for analyzing dental periapical lesions in cone-beam computed tomography (CBCT) scans. In the field of Endodontics, clinical studies have been unable to determine if a periapical granuloma can heal with non-surgical methods. Addressing this issue, Simon et al. recently proposed a diagnostic technique which non-invasively classifies target lesions using CBCT. Manual segmentation exploited in their study, however, is too time consuming and unreliable for real world adoption. On the other hand, many technically advanced algorithms have been proposed to address segmentation problems in various biomedical and non-biomedical contexts, but they have not yet been applied to the field of dentistry. Presented in this paper is a novel application of such segmentation algorithms to the clinically-significant dental problem. This study evaluates three state-of-the-art graph-based algorithms: a normalized cut algorithm based on a generalized eigen-value problem, a graph cut algorithm implementing energy minimization techniques, and a random walks algorithm derived from discrete electrical potential theory. In this paper, we extend the original 2D formulation of the above algorithms to segment 3D images directly and apply the resulting algorithms to the dental CBCT images. We experimentally evaluate quality of the segmentation results for 3D CBCT images, as well as their 2D cross sections. The benefits and pitfalls of each algorithm are highlighted.

  9. Comparison of experimental data and 3D simulations of ion beam neutralization from the neutralized transport experiment

    Thoma, C.; Welch, D.R.; Yu, S.S.; Henestroza, E.; Roy, P.K.; Eylon, S.; Gilson, E.P.

    2004-09-22

    The Neutralized Transport Experiment (NTX) at Lawrence Berkeley National Laboratory has been designed to study the final focus and neutralization of high perveance ion beams for applications in heavy ion fusion (HIF) and high energy density physics (HEDP) experiments. Pre-formed plasmas in the last meter before the target of the scaled experiment provide a source of electrons which neutralize the ion current and prevent the space-charge induced spreading of the beam spot. NTX physics issues are discussed and experimental data is analyzed and compared with 3D particle-in-cell simulations. Along with detailed target images, 4D phase-space data of the NTX at the entrance of the neutralization region has been acquired. This data is used to provide a more accurate beam distribution with which to initialize the simulation. Previous treatments have used various idealized beam distributions which lack the detailed features of the experimental ion beam images. Simulation results are compared with NTX experimental measurements for 250 keV K{sup +} ion beams with dimensionless perveance of 1-7 x 10{sup -4}. In both simulation and experiment, the deduced beam charge neutralization is close to the predicted maximum value.

  10. Reproducibility of mandibular third molar assessment comparing two cone beam CT units in a matched pairs design.

    Matzen, L H; Hintze, H; Spin-Neto, R; Wenzel, A

    2013-01-01

    The aim of this study was to evaluate the reproducibility of the third molar assessment, comparing five observers and two cone beam CT (CBCT) units. 28 patients, each with two impacted mandibular third molars, were included. Each patient was randomly examined with a Scanora(®) 3D (Soredex, Helsinki, Finland) CBCT unit in one mandibular third molar region and with a Cranex(®) 3D (Soredex) CBCT unit in the other region. Five observers with varying CBCT experience assessed all third molars and recorded the following variables: number and morphology of the roots, relation to the mandibular canal in two directions, shape of the canal and whether there was a direct contact between the roots of the molar and the mandibular canal. The radiographic assessments were compared pairwise among all observers for all variables. Wilcoxon's signed-rank test was used to test the differences in observer accordance percentages among the recorded variables in the images from the two units, and kappa statistics expressed interobserver reproducibility. The mean percentages for observer accordance ranged from 65.4 to 92.9 for Scanora 3D and 60.3 to 94.8 for Cranex 3D. There was no significant difference between the observer accordance in the two CBCT units (p > 0.05), except for assessing root flex in the mesiodistal direction, for which the observer accordance was higher for Scanora 3D (p third molar assessment. Observer variation existed, and experienced radiologists demonstrated the highest interobserver reproducibility for canal-related variables.

  11. Cone Beam Computed Tomography-Dawn of A New Imaging Modality in Orthodontics

    Mamatha, J; Chaitra, K R; Paul, Renji K; George, Merin; J. Anitha; Khanna, Bharti

    2015-01-01

    Today, we are in a world of innovations, and there are various diagnostics aids that help to take a decision regarding treatment in a well-planned way. Cone beam computed tomography (CBCT) has been a vital tool for imaging diagnostic tool in orthodontics. This article reviews case reports during orthodontic treatment and importance of CBCT during the treatment evaluation.

  12. Calculating nasoseptal flap dimensions : a cadaveric study using cone beam computed tomography

    ten Dam, Ellen; Korsten-Meijer, Astrid G. W.; Schepers, Rutger H.; van der Meer, Wicher J.; Gerrits, Peter O.; van der Laan, Bernard F. A. M.; Feijen, Robert A.

    2015-01-01

    We hypothesize that three-dimensional imaging using cone beam computed tomography (CBCT) is suitable for calculating nasoseptal flap (NSF) dimensions. To evaluate our hypothesis, we compared CBCT NSF dimensions with anatomical dissections. The NSF reach and vascularity were studied. In an anatomical

  13. Cone Beam Computed Tomography-Dawn of A New Imaging Modality in Orthodontics.

    Mamatha, J; Chaitra, K R; Paul, Renji K; George, Merin; Anitha, J; Khanna, Bharti

    2015-01-01

    Today, we are in a world of innovations, and there are various diagnostics aids that help to take a decision regarding treatment in a well-planned way. Cone beam computed tomography (CBCT) has been a vital tool for imaging diagnostic tool in orthodontics. This article reviews case reports during orthodontic treatment and importance of CBCT during the treatment evaluation.

  14. Evidence supporting the use of cone-beam computed tomography in orthodontics.

    Vlijmen, O.J.C. van; Kuijpers, M.A.R.; Berge, S.J.; Schols, J.G.J.H.; Maal, T.J.J.; Breuning, H.; Kuijpers-Jagtman, A.M.

    2012-01-01

    BACKGROUND: The authors conducted a systematic review of cone-beam computed tomography (CBCT) applications in orthodontics and evaluated the level of evidence to determine whether the use of CBCT is justified in orthodontics. TYPES OF STUDIES REVIEWED: The authors identified articles by searching th

  15. Cone Beam Computed Tomography-Dawn of A New Imaging Modality in Orthodontics

    Mamatha, J; Chaitra, K R; Paul, Renji K; George, Merin; Anitha, J; Khanna, Bharti

    2015-01-01

    Today, we are in a world of innovations, and there are various diagnostics aids that help to take a decision regarding treatment in a well-planned way. Cone beam computed tomography (CBCT) has been a vital tool for imaging diagnostic tool in orthodontics. This article reviews case reports during orthodontic treatment and importance of CBCT during the treatment evaluation. PMID:26225116

  16. Evaluation of web-based instruction for anatomical interpretation in maxillofacial cone beam computed tomography

    Al-Rawi, W.T.; Jacobs, R.; Hassan, B.A.; Sanderink, G.; Scarfe, W.C.

    2007-01-01

    Objectives: To evaluate the effectiveness of a web-based instruction in the interpretation of anatomy in images acquired with maxillofacial cone beam CT (CBCT). Methods: An interactive web-based education course for the interpretation of craniofacial CBCT images was recently developed at our institu

  17. AAE and AAOMR Joint Position Statement: Use of Cone Beam Computed Tomography in Endodontics 2015 Update.

    2015-10-01

    The following statement was prepared by the Special Committee to Revise the Joint American Association of Endodontists/American Academy of Oral and Maxillofacial Radiology Position on Cone Beam Computed Tomography, and approved by the AAE Board of Directors and AAOMR Executive Council in May 2015. AAE members may reprint this position statement for distribution to patients or referring dentists.

  18. Studying the Prevalence and Etiology of Class II Subdivision Malocclusion Utilizing Cone-Beam Computed Tomography

    2013-04-24

    II SUBDIVISION MALOCCLUSION UTILIZING CONE-BEAM COMPUTED TOMOGRAPHY A THESIS Presented to the Faculty of the Uniform Services University of...K_Paper _Article _Book _ Poster _Presentation _Other 6. Title: ’Studying the Prevalence and Etiology of Class II Subdivision Malocclusion Utilizing...of any copyrighted material in the thesis manuscript entitled : ’STUDYING THE PREVALENCE AND ETIOLOGY OF CLASS II SUBDIVISION MALOCCLUSION

  19. Point spread function modeling and images restoration for cone-beam CT

    Zhang, Hua; Shi, Yikai; Xu, Zhe

    2014-01-01

    X-ray cone-beam computed tomography (CT) has the notable features such as high efficiency and precision, and is widely used in the fields of medical imaging and industrial non-destructive testing, but the inherent imaging degradation reduces the quality of CT images. Aimed at the problems of projection images degradation and restoration in cone-beam CT, a point spread function (PSF) modeling method is proposed firstly. The general PSF model of cone-beam CT is established, and based on it, the PSF under arbitrary scanning conditions can be calculated directly for projection images restoration without the additional measurement, which greatly improved the application convenience of cone-beam CT. Secondly, a projection images restoration algorithm based on pre-filtering and pre-segmentation is proposed, which can make the edge contours in projection images and slice images clearer after restoration, and control the noise in the equivalent level to the original images. Finally, the experiments verified the feasib...

  20. Comparison of percutaneous radiologic gastrostomy by using cone beam CT and endoscopic gastrostomy

    Jung, Hyun Nyeong; Han, Young Min; Jin, Gong Yong; Choi, Eun Jeong; Song, Ji Soo [Chonbuk National University Hospital and Medical School, Jeonju (Korea, Republic of)

    2014-01-15

    To compare the effectiveness of percutaneous radiologic gastrostomy (PRG) by using cone beam CT and percutaneous endoscopic gastrostomy (PEG). This study retrospectively reviewed 129 patients who underwent PRG (n = 53) and PEG (n = 76) over a 2-years period. The C-arm cone beam CT images were obtained from all PRG patients before the procedure in order to decide the safest accessing routes. The parameters including technical success rates, complication rates and tube migration rates were all analyzed according to statistical methods. The success rate of tube placement was higher in PRG than in PEG (100% to 93%, p = 0.08). Minor complications occurred in 5 patients of the PRG group (10%; 5/53, 3 wound infection, 2 blood oozing), and occurred in 6 patients of PEG group (7.9%; 6/76, 5 wound infection, 1 esophageal ulcer). Major complications occurred only in 5 patients of PEG group (6.6%; 5/76, 1 panperitonitis, 4 buried bumper syndrome). There were no statistical differences of minor and major complication rates in the two groups (respectively, p = 0.759, p = 0.078). Tube migration rate was lower in PRG than PEG group (7.5% vs. 38.2%, p < 0.005). PRG using cone beam CT is the effective and safe method, the cone beam CT provides the safest accessing route during gastrostomy. Less tube migration occurs in the PRG than in PEG.

  1. Segmentation of the mandibular canal in cone-beam CT data

    Kroon, Dirk-Jan

    2011-01-01

    Accurate information about the location of the mandibular canal is essential in case of dental implant surgery. The goal of our research is to find an automatic method which can segment the mandibular canal in Cone-beam CT (CBCT). Mandibular canal segmentation methods in literature using a priori

  2. Time-resolved cardiac cone beam CT using an interventional C-arm system

    Schomberg, H.

    2012-01-01

    It is both desirable and challenging to make interventional C-arm systems fit for cardiac cone beam CT. A number of methods towards thisgoal have been proposed, some of which even attempt to generate 4Dimages of the beating heart. A promising candidate of this type, proposed earlier by this author,

  3. Accuracy and repeatability of anthropometric facial measurements using cone beam computed tomography

    Fourie, Zacharias; Damstra, Janalt; Gerrits, Peter O.; Ren, Yijin

    2011-01-01

    Objective: The purpose of this study was to determine the accuracy and repeatability of linear anthropometric measurements on the soft tissue surface model generated from cone beam computed tomography scans. Materials and Methods: The study sample consisted of seven cadaver heads. The accuracy and r

  4. Cone-beam computed tomography: An inevitable investigation in cleidocranial dysplasia

    Nandita S Gupta

    2015-01-01

    Full Text Available Cleidocranial dysplasia is a heritable skeletal dysplasia and one of the most common features of this syndrome is multiple impacted supernumerary teeth. Cone-beam computed tomography, the most recent advancement in maxillofacial imaging, provides the clinician to view the morphology of the skull and the dentition in all three dimensions and help in treatment planning for the patient.

  5. State-of-the-art on cone beam CT imaging for preoperative planning of implant placement.

    Guerrero, M.E.; Jacobs, R.; Loubele, M.; Schutyser, F.A.C.; Suetens, P.; Steenberghe, D van

    2006-01-01

    Orofacial diagnostic imaging has grown dramatically in recent years. As the use of endosseous implants has revolutionized oral rehabilitation, a specialized technique has become available for the preoperative planning of oral implant placement: cone beam computed tomography (CT). This imaging techno

  6. The outcome of root-canal treatments assessed by cone-beam computed tomography

    Liang, Y.H.

    2013-01-01

    In this thesis, in-vivo and ex-vivo methods were utilized to assess the outcome of root canal treatments determined by cone-beam computed tomography (CBCT) and the reliability of the CBCT-findings. CBCT provided useful and reliable information leading to a better understanding of the outcome and fac

  7. Integration of digital dental casts in cone-beam computed tomography scans

    Rangel, F.A.; Maal, T.J.J.; Berge, S.J.; Kuijpers-Jagtman, A.M.

    2012-01-01

    Cone-beam computed tomography (CBCT) is widely used in maxillofacial surgery. The CBCT image of the dental arches, however, is of insufficient quality to use in digital planning of orthognathic surgery. Several authors have described methods to integrate digital dental casts into CBCT scans, but all

  8. Diagnosis and decision making in endodontics with the use of cone beam computed tomography

    Metska, M.E.

    2014-01-01

    In the current thesis the use of cone beam computed tomography (CBCT) in endodontics has been evaluated within the framework of ex vivo and in vivo studies. The first objective of the thesis was to examine whether CBCT scans can be used for the detection of vertical root fractures in endodontically

  9. Contours identification of elements in a cone beam computed tomography for investigating maxillary cysts

    Chioran, Doina; Nicoarǎ, Adrian; Roşu, Şerban; Cǎrligeriu, Virgil; Ianeş, Emilia

    2013-10-01

    Digital processing of two-dimensional cone beam computer tomography slicesstarts by identification of the contour of elements within. This paper deals with the collective work of specialists in medicine and applied mathematics in computer science on elaborating and implementation of algorithms in dental 2D imagery.

  10. Simulation of 3-D radiation beam patterns propagated through a planar interface from ultrasonic phased array transducers.

    Song, Sung-Jin; Kim, Chang-Hwan

    2002-05-01

    Phased array transducers are quite often mounted on solid wedges with specific angles in many practical ultrasonic inspections of thin plates phased array techniques with testing set-up, it is essential to have thorough understanding on the characteristics of radiation beam pattern produced in the interrogated medium. To address such a need, this paper proposes a systematic way to calculate full 3-D radiation beam patterns produced in the interrogated solid medium by phased array transducers mounted on a solid wedge. In order to investigate the characteristics of radiation beam patterns in steel, simulation is carried out for 7.5 MHz array transducers mounted on an acrylic wedge with the angle of 15.45 degrees with various of steering angles and/or focal planes.

  11. Taming the degeneration of Bessel beams at anisotropic-isotropic interface: toward 3D control of confined vortical waves

    Riaud, Antoine; Baudoin, Michael; Matar, Olivier Bou

    2015-01-01

    Despite their self-reconstruction properties in heterogeneous media, Bessel beams are known to degenerate when they are refracted from an isotropic to an anisotropic medium. In this paper, we study the converse situation wherein an anisotropic Bessel beam is refracted into an isotropic medium. It is shown that these anisotropic Bessel beams also degenerate, leading to confined vortical waves that may serve as localized particle trap for acoustical tweezers. The linear nature of this degeneration allows the 3D control of this trap position by wavefront correction. Theory is confronted to experiments performed in the field of acoustics. A swirling surface acoustic wave is synthesized at the surface of a piezoelectric crystal by a MEMS integrated system and radiated inside a miniature liquid vessel. The wavefront correction is operated with inverse filter technique. This work opens perspectives for contactless on-chip manipulation devices.

  12. Reconstruction of 3D ion beam micro-tomography data for applications in Cell Biology

    Habchi, C. [Universite de Bordeaux, Centre d' Etudes Nucleaires de Bordeaux Gradignan, UMR 5797, Gradignan F-33175 (France)], E-mail: habchi@cenbg.in2p3.fr; Nguyen, D.T.; Barberet, Ph. [Universite de Bordeaux, Centre d' Etudes Nucleaires de Bordeaux Gradignan, UMR 5797, Gradignan F-33175 (France); Incerti, S. [CNRS/IN2P3, Centre d' Etudes Nucleaires de Bordeaux Gradignan, UMR 5797, Gradignan F-33175 (France); Moretto, Ph. [Universite de Bordeaux, Centre d' Etudes Nucleaires de Bordeaux Gradignan, UMR 5797, Gradignan F-33175 (France); Sakellariou, A. [Research School of Physical Sciences and Engineering, Australian National University, Canberra ACT 0200 (Australia); Seznec, H. [CNRS/IN2P3, Centre d' Etudes Nucleaires de Bordeaux Gradignan, UMR 5797, Gradignan F-33175 (France)

    2009-06-15

    The DISRA (Discrete Image Space Reconstruction Algorithm) reconstruction code, created by A. Sakellariou, was conceived for the ideal case of complete three-dimensional (3D) PIXET (Particle Induced X-ray Emission Tomography) data. This implies two major difficulties for biological samples: first, the long duration of such experiments and second, the subsequent damage that occurs on such fragile specimens. For this reason, the DISRA code was extended at CENBG in order to probe isolated PIXET slices, taking into account the sample structure and mass density provided by 3D STIMT (Scanning Transmission Ion Microscopy Tomography) in the volume of interest. This modified version was tested on a phantom sample and first results on human cancer cells are also presented.

  13. Reconstruction of 3D ion beam micro-tomography data for applications in Cell Biology

    Habchi, C.; Nguyen, D. T.; Barberet, Ph.; Incerti, S.; Moretto, Ph.; Sakellariou, A.; Seznec, H.

    2009-06-01

    The DISRA (Discrete Image Space Reconstruction Algorithm) reconstruction code, created by A. Sakellariou, was conceived for the ideal case of complete three-dimensional (3D) PIXET (Particle Induced X-ray Emission Tomography) data. This implies two major difficulties for biological samples: first, the long duration of such experiments and second, the subsequent damage that occurs on such fragile specimens. For this reason, the DISRA code was extended at CENBG in order to probe isolated PIXET slices, taking into account the sample structure and mass density provided by 3D STIMT (Scanning Transmission Ion Microscopy Tomography) in the volume of interest. This modified version was tested on a phantom sample and first results on human cancer cells are also presented.

  14. Autonomous and 3D real-time multi-beam manipulation in a microfluidic environment

    Perch-Nielsen, I.; Rodrigo, P.J.; Alonzo, C.A.; Glückstad, J

    2006-01-01

    The Generalized Phase Contrast (GPC) method of optical 3D manipulation has previously been used for controlled spatial manipulation of live biological specimen in real-time. These biological experiments were carried out over a time-span of several hours while an operator intermittently optimized the optical system. Here we present GPC-based optical micromanipulation in a microfluidic system where trapping experiments are computer-automated and thereby capable of running with only limited supe...

  15. Beam test measurements with planar and 3D silicon strip detectors irradiated to sLHC fluences

    Kohler, Michael; Wiik, Liv; /Freiburg U.; Bates, Richard; /Glasgow U.; Dalla Betta, Gian-Franco; /INFN, Trento /Trento U.; Fleta, Celeste; /Barcelona, Inst. Microelectron.; Harkonen, Jaakko; /Helsinki Inst. of Phys.; Jakobs, Karl; /Freiburg U.; Lozano, Manuel; /Barcelona, Inst. Microelectron.; Maenpaa, Teppo; Moilanen, Henri; /Helsinki Inst. of Phys.; Parkes, Chris; /Glasgow U. /Freiburg U. /Barcelona, Inst. Microelectron. /Fermilab

    2011-01-01

    The planned luminosity upgrade of the CERN LHC to the super LHC (sLHC) requires investigation of new radiation hard tracking detectors. Compared to the LHC, tracking detectors must withstand a 5-10 times higher radiation fluence. Promising radiation hard options are planar silicon detectors with n-side readout and silicon detectors in 3D technology, where columnar electrodes are etched into the silicon substrate. This article presents beam test measurements per formed with planar and 3D n-in-p silicon strip detectors. The detectors were irradiated to different fluences, where the maximum fluence was 3 x 10{sup 15} 1 MeV neutron equivalent particles per square centimeter (n{sub eq}/cm{sup 2}) for the planar detectors and 2 x 10{sup 15} n{sub eq}/cm{sup 2} for the 3D detectors. In addition to signal measurements, charge sharing and resolution of both detector technologies are compared. An increased signal from the irradiated 3D detectors at high bias voltages compared to the signal from the unirradiated detector indicates that charge multiplication effects occur in the 3D detectors. At a bias voltage of 260 V, the 3D detector irradiated to 2 x 10{sup 15} n{sub eq}/cm{sup 2} yields a signal almost twice as high as the signal of the unirradiated detector. Only 30% of the signal of an unirradiated detector could be measured with the planar detector irradiated to 3 x 10{sup 15} n{sub eq}/cm{sup 2} at a bias voltage of 600 V, which was the highest bias voltage applied to this sensor.

  16. Comparison of mesiodistal root angulation with posttreatment panoramic radiographs and cone-beam computed tomography

    Bouwens, Daniel G.; Cevidanes, Lucia; Ludlow, John B.; Phillips, Ceib

    2011-01-01

    Introduction Orthodontists assess mesiodistal root angulations before, during, and after orthodontic treatment as an aid in establishing proper root position. Panoramic imaging has been useful for this purpose and is a valuable screening tool in diagnosis and planning treatment of orthodontic patients. Cone-beam computed tomography (CBCT) for imaging of the craniofacial complex creates the opportunity to evaluate 3-dimensional images compared with traditional 2-dimensional images. The purpose of this project was to compare mesiodistal root angulations by using posttreatment panoramic radiographic images and CBCT scans. Methods Mesiodistal root angulations from panoramic images and CBCT scans of 35 orthognathic surgery patients after orthodontic treatment were compared. The panoramic images were measured by using VixWin (Gendex Dental Systems, Des Plaines, Ill), and the CBCT scans by using InvivoDental 3D (version 4.1, Anatomage, San Jose, Calif). The mesiodistal root angulation of each maxillary and mandibular tooth was measured by using the occlusal plane as the reference line. With an intercept-only linear regression for correlated data (with an unstructured covariance structure), the global test of whether the mean vector of all differences for the teeth is zero was performed separately for the 2 arches. Results The global test for both arches was statistically significant (P<0.001), indicating an overall difference in root angulation between measurements from panoramic and CBCT images. There was no discernible pattern in the average differences between panoramic and CBCT measurements. Conclusions The assessment of mesiodistal tooth angulation with panoramic radiography should be approached with caution and reinforced by a thorough clinical examination of the dentition. PMID:21195286

  17. Fully automatic segmentation of arbitrarily shaped fiducial markers in cone-beam CT projections

    Bertholet, J.; Wan, H.; Toftegaard, J.; Schmidt, M. L.; Chotard, F.; Parikh, P. J.; Poulsen, P. R.

    2017-02-01

    Radio-opaque fiducial markers of different shapes are often implanted in or near abdominal or thoracic tumors to act as surrogates for the tumor position during radiotherapy. They can be used for real-time treatment adaptation, but this requires a robust, automatic segmentation method able to handle arbitrarily shaped markers in a rotational imaging geometry such as cone-beam computed tomography (CBCT) projection images and intra-treatment images. In this study, we propose a fully automatic dynamic programming (DP) assisted template-based (TB) segmentation method. Based on an initial DP segmentation, the DPTB algorithm generates and uses a 3D marker model to create 2D templates at any projection angle. The 2D templates are used to segment the marker position as the position with highest normalized cross-correlation in a search area centered at the DP segmented position. The accuracy of the DP algorithm and the new DPTB algorithm was quantified as the 2D segmentation error (pixels) compared to a manual ground truth segmentation for 97 markers in the projection images of CBCT scans of 40 patients. Also the fraction of wrong segmentations, defined as 2D errors larger than 5 pixels, was calculated. The mean 2D segmentation error of DP was reduced from 4.1 pixels to 3.0 pixels by DPTB, while the fraction of wrong segmentations was reduced from 17.4% to 6.8%. DPTB allowed rejection of uncertain segmentations as deemed by a low normalized cross-correlation coefficient and contrast-to-noise ratio. For a rejection rate of 9.97%, the sensitivity in detecting wrong segmentations was 67% and the specificity was 94%. The accepted segmentations had a mean segmentation error of 1.8 pixels and 2.5% wrong segmentations.

  18. Cone-Beam Computed Tomography (CBCT) Versus CT in Lung Ablation Procedure: Which is Faster?

    Cazzato, Roberto Luigi, E-mail: r.cazzato@unicampus.it; Battistuzzi, Jean-Benoit, E-mail: j.battistuzzi@bordeaux.unicancer.fr; Catena, Vittorio, E-mail: vittoriocatena@gmail.com [Institut Bergonié, Department of Radiology (France); Grasso, Rosario Francesco, E-mail: r.grasso@unicampus.it; Zobel, Bruno Beomonte, E-mail: b.zobel@unicampus.it [Università Campus Bio-Medico di Roma, Department of Radiology and Diagnostic Imaging (Italy); Schena, Emiliano, E-mail: e.schena@unicampus.it [Università Campus Bio-Medico di Roma, Unit of Measurements and Biomedical Instrumentations, Biomedical Engineering Laboratory (Italy); Buy, Xavier, E-mail: x.buy@bordeaux.unicancer.fr; Palussiere, Jean, E-mail: j.palussiere@bordeaux.unicancer.fr [Institut Bergonié, Department of Radiology (France)

    2015-10-15

    AimTo compare cone-beam CT (CBCT) versus computed tomography (CT) guidance in terms of time needed to target and place the radiofrequency ablation (RFA) electrode on lung tumours.Materials and MethodsPatients at our institution who received CBCT- or CT-guided RFA for primary or metastatic lung tumours were retrospectively included. Time required to target and place the RFA electrode within the lesion was registered and compared across the two groups. Lesions were stratified into three groups according to their size (<10, 10–20, >20 mm). Occurrences of electrode repositioning, repositioning time, RFA complications, and local recurrence after RFA were also reported.ResultsForty tumours (22 under CT, 18 under CBCT guidance) were treated in 27 patients (19 male, 8 female, median age 67.25 ± 9.13 years). Thirty RFA sessions (16 under CBCT and 14 under CT guidance) were performed. Multivariable linear regression analysis showed that CBCT was faster than CT to target and place the electrode within the tumour independently from its size (β = −9.45, t = −3.09, p = 0.004). Electrode repositioning was required in 10/22 (45.4 %) tumours under CT guidance and 5/18 (27.8 %) tumours under CBCT guidance. Pneumothoraces occurred in 6/14 (42.8 %) sessions under CT guidance and in 6/16 (37.5 %) sessions under CBCT guidance. Two recurrences were noted for tumours receiving CBCT-guided RFA (2/17, 11.7 %) and three after CT-guided RFA (3/19, 15.8 %).ConclusionCBCT with live 3D needle guidance is a useful technique for percutaneous lung ablation. Despite lesion size, CBCT allows faster lung RFA than CT.

  19. Comparison of Swedish and Norwegian Use of Cone-Beam Computed Tomography: a Questionnaire Study

    Jerker Edén Strindberg

    2015-12-01

    Full Text Available Objectives: Cone-beam computed tomography in dentistry can be used in some countries by other dentists than specialists in radiology. The frequency of buying cone-beam computed tomography to examine patients is rapidly growing, thus knowledge of how to use it is very important. The aim was to compare the outcome of an investigation on the use of cone-beam computed tomography in Sweden with a previous Norwegian study, regarding specifically technical aspects. Material and Methods: The questionnaire contained 45 questions, including 35 comparable questions to Norwegian clinics one year previous. Results were based on inter-comparison of the outcome from each of the two questionnaire studies. Results: Responses rate was 71% in Sweden. There, most of cone-beam computed tomography (CBCT examinations performed by dental nurses, while in Norway by specialists. More than two-thirds of the CBCT units had a scout image function, regularly used in both Sweden (79% and Norway (75%. In Sweden 4% and in Norway 41% of the respondents did not wait for the report from the radiographic specialist before initiating treatment. Conclusions: The bilateral comparison showed an overall similarity between the two countries. The survey gave explicit and important knowledge of the need for education and training of the whole team, since radiation dose to the patient could vary a lot for the same kind of radiographic examination. It is essential to establish quality assurance protocols with defined responsibilities in the team in order to maintain high diagnostic accuracy for all examinations when using cone-beam computed tomography for patient examinations.

  20. Study of plasma meniscus formation and beam halo in negative ion source using the 3D3VPIC model

    Nishioka, S.; Goto, I.; Hatayama, A. [Graduate school of Science and Technology, Keio University, Hiyoshi, Kohoku-ku, Yokohama 223-8522 (Japan); Miyamoto, K. [Naruto University of Education, 748 Nakashima, Takashima, Naruto-cho, Naruto-shi, Tokushima 772-8502 (Japan); Fukano, A. [Tokyo Metropolitan Collage of Industrial Technology, Higashioi, Shinagawa, Tokyo 140-0011 (Japan)

    2015-04-08

    In this paper, the effect of the electron confinement time on the plasma meniscus and the fraction of the beam halo is investigated by 3D3V-PIC (three dimension in real space and three dimension in velocity space) (Particle in Cell) simulation in the extraction region of negative ion source. The electron confinement time depends on the characteristic time of electron escape along the magnetic field as well as the characteristic time of diffusion across the magnetic field. Our 3D3V-PIC results support the previous result by 2D3V-PIC results i.e., it is confirmed that the penetration of the plasma meniscus becomes deep into the source plasma region when the effective confinement time is short.

  1. Autonomous and 3D real-time multi-beam manipulation in a microfluidic environment

    Perch-Nielsen, I.; Rodrigo, P.J.; Alonzo, C.A.

    2006-01-01

    The Generalized Phase Contrast (GPC) method of optical 3D manipulation has previously been used for controlled spatial manipulation of live biological specimen in real-time. These biological experiments were carried out over a time-span of several hours while an operator intermittently optimized...... the optical system. Here we present GPC-based optical micromanipulation in a microfluidic system where trapping experiments are computer-automated and thereby capable of running with only limited supervision. The system is able to dynamically detect living yeast cells using a computer-interfaced CCD camera...... lateral stiffness of GPC-based optical traps. (c) 2006 Optical Society of America...

  2. Scanning cross-correlator for monitoring uniform 3D ellipsoidal laser beams

    Zelenogorskii, V V; Gacheva, E I; Gelikonov, G V; Krasilnikov, M; Mart'yanov, M A; Mironov, S Yu; Potemkin, A K; Syresin, E M; Stephan, F; Khazanov, E A

    2014-01-01

    The specific features of experimental implementation of a cross-correlator with a scan rate above 1600 cm s(-1) and a spatial delay amplitude of more than 15 mm are considered. The possibility of measuring the width of femtosecond pulses propagating in a train 300 mu s in duration with a repetition rate of 1 MHz is demonstrated. A time resolution of 300 fs for the maximum time window of 50 ps is attained.The cross-correlator is aimed at testing 3D pulses of a laser driver of an electron photo-injector.

  3. Beam section stiffness properties using a single layer of 3D solid elements

    Couturier, Philippe; Krenk, Steen; Høgsberg, Jan Becker

    2015-01-01

    A method is presented for analysis of the properties of general cross-sections with arbitrary geometry and material distribution. The full six by six cross-section stiffness matrix is evaluated from a single element thickness slice represented by 3D solid elements with lengthwise Hermitian...... interpolation with six independent imposed deformation modes corresponding to extension, torsion, bending and shear. The flexibility matrix of the slice is obtained from complementary elastic energy, and the stiffness matrix is obtained by extracting and inverting the cross-section flexibility. Three examples...

  4. Design and development of C-arm based cone-beam CT for image-guided interventions: initial results

    Chen, Guang-Hong; Zambelli, Joseph; Nett, Brian E.; Supanich, Mark; Riddell, Cyril; Belanger, Barry; Mistretta, Charles A.

    2006-03-01

    X-ray cone-beam computed tomography (CBCT) is of importance in image-guided intervention (IGI) and image-guided radiation therapy (IGRT). In this paper, we present a cone-beam CT data acquisition system using a GE INNOVA 4100 (GE Healthcare Technologies, Waukesha, Wisconsin) clinical system. This new cone-beam data acquisition mode was developed for research purposes without interfering with any clinical function of the system. It provides us a basic imaging pipeline for more advanced cone-beam data acquisition methods. It also provides us a platform to study and overcome the limiting factors such as cone-beam artifacts and limiting low contrast resolution in current C-arm based cone-beam CT systems. A geometrical calibration method was developed to experimentally determine parameters of the scanning geometry to correct the image reconstruction for geometric non-idealities. Extensive phantom studies and some small animal studies have been conducted to evaluate the performance of our cone-beam CT data acquisition system.

  5. A 3D model for ion beam formation and transport simulation

    Qiang, J.; Todd, D.; Leitner, D.

    2006-09-01

    In this paper, we present a three-dimensional model for self consistently modeling ion beam formation from plasma ion sources and transporting in low energy beam transport systems. A multi-section overlapped computational domain has been used to break the original transport system into a number of weakly coupled subsystems. Within each subsystem, macro-particle tracking is used to obtain the charge density distribution in this subdomain. The three-dimensional Poisson equation is solved within the subdomain after each particle tracking to obtain the self-consistent space-charge forces and the particle tracking is repeated until the solution converges. Two new Poisson solvers based on a combination of the spectral method and the finite difference multigrid method have been developed to solve the Poisson equation in cylindrical coordinates for the straight beam transport section and in Frenet-Serret coordinates for the bending magnet section. This model can have important application in design and optimization of the low energy beam line optics of the proposed Rare Isotope Accelerator (RIA) front end.

  6. Fabrication and characterisation of a fully auxetic 3D lattice structure via selective electron beam melting

    Warmuth, Franziska; Osmanlic, Fuad; Adler, Lucas; Lodes, Matthias A.; Körner, Carolin

    2017-02-01

    A three-dimensional fully auxetic cellular structure with negative Poisson’s ratio is presented. Samples are fabricated from Ti6Al4V powder via selective electron beam melting. The influence of the strut thickness and the amplitude of the strut on the mechanical properties and the deformation behaviour of cellular structures is studied.

  7. Cone-beam computed tomography: A miracle for orthodontics!

    Jeevan M Khatri; Gaurav Tated

    2015-01-01

    The branch of oral medicine and radiology has always played a role of back stage worker for the branch of orthodontics and dentofacial orthopaedics. It would have been difficult for an orthodontist to gift the bright smiles to his/her patients without the 2D and 3D black and white pictures provided by the oral radiologist. Moreover, the series of advances in the various imaging modalities are playing the role of a magician for the branch of orthodontia. The present article provides valuable i...

  8. Moving metal artifact reduction in cone-beam CT scans with implanted cylindrical gold markers

    Toftegaard, Jakob, E-mail: jaktofte@rm.dk; Fledelius, Walther; Worm, Esben S.; Poulsen, Per R. [Department of Oncology, Aarhus University Hospital, Aarhus 8000 (Denmark); Seghers, Dieter; Huber, Michael; Brehm, Marcus [Varian Medical Systems, Imaging Laboratory GmbH, Baden-Daettwil 5405 (Switzerland); Elstrøm, Ulrik V. [Department of Medical Physics, Aarhus University Hospital, Aarhus 8000 (Denmark)

    2014-12-15

    Purpose: Implanted gold markers for image-guided radiotherapy lead to streaking artifacts in cone-beam CT (CBCT) scans. Several methods for metal artifact reduction (MAR) have been published, but they all fail in scans with large motion. Here the authors propose and investigate a method for automatic moving metal artifact reduction (MMAR) in CBCT scans with cylindrical gold markers. Methods: The MMAR CBCT reconstruction method has six steps. (1) Automatic segmentation of the cylindrical markers in the CBCT projections. (2) Removal of each marker in the projections by replacing the pixels within a masked area with interpolated values. (3) Reconstruction of a marker-free CBCT volume from the manipulated CBCT projections. (4) Reconstruction of a standard CBCT volume with metal artifacts from the original CBCT projections. (5) Estimation of the three-dimensional (3D) trajectory during CBCT acquisition for each marker based on the segmentation in Step 1, and identification of the smallest ellipsoidal volume that encompasses 95% of the visited 3D positions. (6) Generation of the final MMAR CBCT reconstruction from the marker-free CBCT volume of Step 3 by replacing the voxels in the 95% ellipsoid with the corresponding voxels of the standard CBCT volume of Step 4. The MMAR reconstruction was performed retrospectively using a half-fan CBCT scan for 29 consecutive stereotactic body radiation therapy patients with 2–3 gold markers implanted in the liver. The metal artifacts of the MMAR reconstructions were scored and compared with a standard MAR reconstruction by counting the streaks and by calculating the standard deviation of the Hounsfield units in a region around each marker. Results: The markers were found with the same autosegmentation settings in 27 CBCT scans, while two scans needed slightly changed settings to find all markers automatically in Step 1 of the MMAR method. MMAR resulted in 15 scans with no streaking artifacts, 11 scans with 1–4 streaks, and 3 scans

  9. Cone-beam CT with a flat-panel detector: From image science to image-guided surgery

    Siewerdsen, Jeffrey H., E-mail: jeff.siewerdsen@jhu.edu [Department of Biomedical Engineering, Johns Hopkins University, Traylor Building, Room 718, 720 Rutland Avenue, Baltimore, MD 21205 (United States)

    2011-08-21

    The development of large-area flat-panel X-ray detectors (FPDs) has spurred investigation in a spectrum of advanced medical imaging applications, including tomosynthesis and cone-beam CT (CBCT). Recent research has extended image quality metrics and theoretical models to such applications, providing a quantitative foundation for the assessment of imaging performance as well as a general framework for the design, optimization, and translation of such technologies to new applications. For example, cascaded systems models of the Fourier domain metrics, such as noise-equivalent quanta (NEQ), have been extended to these modalities to describe the propagation of signal and noise through the image acquisition and reconstruction chain and to quantify the factors that govern spatial resolution, image noise, and detectability. Moreover, such models have demonstrated basic agreement with human observer performance for a broad range of imaging conditions and imaging tasks. These developments in image science have formed a foundation for the knowledgeable development and translation of CBCT to new applications in image-guided interventions-for example, CBCT implemented on a mobile surgical C-arm for intraoperative 3D imaging. The ability to acquire high-quality 3D images on demand during surgical intervention overcomes conventional limitations of surgical guidance in the context of preoperative images alone. A prototype mobile C-arm developed in academic-industry partnership demonstrates CBCT with low radiation dose, sub-mm spatial resolution, and soft-tissue visibility potentially approaching that of diagnostic CT. Integration of the 3D imaging system with real-time tracking, deformable registration, endoscopic video, and 3D visualization offers a promising addition to the surgical arsenal in interventions ranging from head-and-neck/skull base surgery to spine, orthopaedic, thoracic, and abdominal surgeries. Cadaver studies show the potential for significant boosts in surgical

  10. Cone-beam CT with a flat-panel detector: From image science to image-guided surgery

    Siewerdsen, Jeffrey H.

    2011-08-01

    The development of large-area flat-panel X-ray detectors (FPDs) has spurred investigation in a spectrum of advanced medical imaging applications, including tomosynthesis and cone-beam CT (CBCT). Recent research has extended image quality metrics and theoretical models to such applications, providing a quantitative foundation for the assessment of imaging performance as well as a general framework for the design, optimization, and translation of such technologies to new applications. For example, cascaded systems models of the Fourier domain metrics, such as noise-equivalent quanta (NEQ), have been extended to these modalities to describe the propagation of signal and noise through the image acquisition and reconstruction chain and to quantify the factors that govern spatial resolution, image noise, and detectability. Moreover, such models have demonstrated basic agreement with human observer performance for a broad range of imaging conditions and imaging tasks. These developments in image science have formed a foundation for the knowledgeable development and translation of CBCT to new applications in image-guided interventions—for example, CBCT implemented on a mobile surgical C-arm for intraoperative 3D imaging. The ability to acquire high-quality 3D images on demand during surgical intervention overcomes conventional limitations of surgical guidance in the context of preoperative images alone. A prototype mobile C-arm developed in academic-industry partnership demonstrates CBCT with low radiation dose, sub-mm spatial resolution, and soft-tissue visibility potentially approaching that of diagnostic CT. Integration of the 3D imaging system with real-time tracking, deformable registration, endoscopic video, and 3D visualization offers a promising addition to the surgical arsenal in interventions ranging from head-and-neck/skull base surgery to spine, orthopaedic, thoracic, and abdominal surgeries. Cadaver studies show the potential for significant boosts in

  11. Evaluation of Cone Beam Computed Tomography in Diagnosis and Treatment Plan of Impacted Maxillary Canines Evaluation of Cone Beam Computed Tomography in Diagnosis and Treatment Plan of Impacted Maxillary Canines

    Seyed Hossein Hoseini Zarch

    2013-06-01

    Full Text Available Introduction: Maxillary canines have important roles in facial appearance, development of arch, and functional occlusion. Radiographs are important in evaluating the location and nature of these anomalies. The purpose of this study was to evaluate two types of 2D and 3D imaging technique in diagnosis and treatment of maxillary impacted canines. Methods: Thirty eight patients (50 impacted canines were enrolled. An oral radiologist assessed all of patients’ panoramic radiographs and then cone beam computed tomography (CBCT to determine the presence of adjacent teeth root resorption, root dilacerations before dental extraction, dental rotation, and buccolingual localization ofimpacted canine crown and root contact with sinus and nasal cavity.Then using the patient’s radiographs the treatment plan of each impacted canine was determined by an orthodontist. Results: Differences between panoramic radiography and CBCT in diagnosis of root resorption and dental rotation were significant. There was an agreement between panoramic radiographs and CBCT in localization of impacted teeth crown. Only the treatment plans of 20% of impacted canines were different between panoramic radiographs and CBCT and treatment plan of 80% of impacted teeth was similar. Conclusion: These results showed that 2D and 3D images of impacted maxillary canines can produce different diagnoses and treatment plans.  

  12. Accuracy Assessment of Three-dimensional Surface Reconstructions of In vivo Teeth from Cone-beam Computed Tomography

    Sang, Yan-Hui; Hu, Hong-Cheng; Lu, Song-He; Wu, Yu-Wei; Li, Wei-Ran; Tang, Zhi-Hui

    2016-01-01

    Background: The accuracy of three-dimensional (3D) reconstructions from cone-beam computed tomography (CBCT) has been particularly important in dentistry, which will affect the effectiveness of diagnosis, treatment plan, and outcome in clinical practice. The aims of this study were to assess the linear, volumetric, and geometric accuracy of 3D reconstructions from CBCT and to investigate the influence of voxel size and CBCT system on the reconstructions results. Methods: Fifty teeth from 18 orthodontic patients were assigned to three groups as NewTom VG 0.15 mm group (NewTom VG; voxel size: 0.15 mm; n = 17), NewTom VG 0.30 mm group (NewTom VG; voxel size: 0.30 mm; n = 16), and VATECH DCTPRO 0.30 mm group (VATECH DCTPRO; voxel size: 0.30 mm; n = 17). The 3D reconstruction models of the teeth were segmented from CBCT data manually using Mimics 18.0 (Materialise Dental, Leuven, Belgium), and the extracted teeth were scanned by 3Shape optical scanner (3Shape A/S, Denmark). Linear and volumetric deviations were separately assessed by comparing the length and volume of the 3D reconstruction model with physical measurement by paired t-test. Geometric deviations were assessed by the root mean square value of the imposed 3D reconstruction and optical models by one-sample t-test. To assess the influence of voxel size and CBCT system on 3D reconstruction, analysis of variance (ANOVA) was used (α = 0.05). Results: The linear, volumetric, and geometric deviations were −0.03 ± 0.48 mm, −5.4 ± 2.8%, and 0.117 ± 0.018 mm for NewTom VG 0.15 mm group; −0.45 ± 0.42 mm, −4.5 ± 3.4%, and 0.116 ± 0.014 mm for NewTom VG 0.30 mm group; and −0.93 ± 0.40 mm, −4.8 ± 5.1%, and 0.194 ± 0.117 mm for VATECH DCTPRO 0.30 mm group, respectively. There were statistically significant differences between groups in terms of linear measurement (P CBCT data can achieve a high linear, volumetric, and geometric accuracy. Increasing voxel resolution from 0.30 to 0.15 mm does not result

  13. Adaptive laser beam forming for laser shock micro-forming for 3D MEMS devices fabrication

    Zou, Ran; Wang, Shuliang; Wang, Mohan; Li, Shuo; Huang, Sheng; Lin, Yankun; Chen, Kevin P.

    2016-07-01

    Laser shock micro-forming is a non-thermal laser forming method that use laser-induced shockwave to modify surface properties and to adjust shapes and geometry of work pieces. In this paper, we present an adaptive optical technique to engineer spatial profiles of the laser beam to exert precision control on the laser shock forming process for free-standing MEMS structures. Using a spatial light modulator, on-target laser energy profiles are engineered to control shape, size, and deformation magnitude, which has led to significant improvement of the laser shock processing outcome at micrometer scales. The results presented in this paper show that the adaptive-optics laser beam forming is an effective method to improve both quality and throughput of the laser forming process at micrometer scales.

  14. 3D Finite Element Numerical Simulation of Residual Stresses on Electron Beam Welded BT20 Plates

    Lixing HUO; Furong CHEN; Yufeng ZHANG; Li ZHANG; Fangjun LIU; Gang CHEN

    2004-01-01

    A three-dimensional finite-element model (FEM) used for calculating electron beam (EB) welding temperature and stresses fields of thin plates of BT20 titanium has been developed in which the nonlinear thermophysical and thermo-mechanical properties of the material has been considered. The welding temperature field, the distributions of residual stresses in aswelded (AW) and electron beam local post-weld heat treatment (EBLPWHT) conditions have been successfully simulated.The results show that: (1) In the weld center, the maximum magnitude of residual tensile stresses of BT20 thin plates of Ti alloy is equal to 60%~ 70% of its yield strength σs. (2) The residual tensile stresses in weld center can be even decreased after EBLPWHT and the longitudinal tensile stresses are decreased about 50% compared to joints in AW conditions. (3)The numerical calculating results of residual stresses by using FEM are basically in agreement with the experimental results.Combined with numerical calculating results, the effects of electron beam welding and EBLPWHT on the distribution of welding residual stresses in thin plates of BT20 have been analyzed in detail.

  15. Electromagnetic scattering of a vector Bessel beam in the presence of an impedance cone

    Salem, Mohamed

    2013-07-01

    The electromagnetic field scattering of a vector Bessel beam in the presence of an infinite circular cone with an impedance boundary on its surface is considered. The impinging field is normal to the tip of the cone and is expanded in terms of vector spherical wave functions; a Kontorovich-Lebedev (KL) transform is employed to expand the scattered fields. The problem is reduced to a singular integral equation with a variable coefficient of the non-convolution type. The singularities of the spectral function are deduced and representations for the field at the tip of the cone as well as other regions are given together with the conditions of validity of these representations. © 2013 IEEE.

  16. 3D DVH-based metric analysis versus per-beam planar analysis in IMRT pretreatment verification

    Carrasco, Pablo; Jornet, Nuria; Latorre, Artur; Eudaldo, Teresa; Ruiz, Agusti; Ribas, Montserrat [Servei de Radiofisica i Radioproteccio, Hospital de la Santa Creu i Sant Pau, Sant Antoni Maria Claret, 167, 08025 Barcelona (Spain)

    2012-08-15

    Purpose: To evaluate methods of pretreatment IMRT analysis, using real measurements performed with a commercial 2D detector array, for clinical relevance and accuracy by comparing clinical DVH parameters. Methods: We divided the work into two parts. The first part consisted of six in-phantom tests aimed to study the sensitivity of the different analysis methods. Beam fluences, 3D dose distribution, and DVH of an unaltered original plan were compared to those of the delivered plan, in which an error had been intentionally introduced. The second part consisted of comparing gamma analysis with DVH metrics for 17 patient plans from various sites. Beam fluences were measured with the MapCHECK 2 detector, per-beam planar analysis was performed with the MapCHECK software, and 3D gamma analysis and the DVH evaluation were performed using 3DVH software. Results: In a per-beam gamma analysis some of the tests yielded false positives or false negatives. However, the 3DVH software correctly described the DVH of the plan which included the error. The measured DVH from the plan with controlled error agreed with the planned DVH within 2% dose or 2% volume. We also found that a gamma criterion of 3%/3 mm was too lax to detect some of the forced errors. Global analysis masked some problems, while local analysis magnified irrelevant errors at low doses. Small hotspots were missed for all metrics due to the spatial resolution of the detector panel. DVH analysis for patient plans revealed small differences between treatment plan calculations and 3DVH results, with the exception of very small volume structures such as the eyes and the lenses. Target coverage (D{sub 98} and D{sub 95}) of the measured plan was systematically lower than that predicted by the treatment planning system, while other DVH characteristics varied depending on the parameter and organ. Conclusions: We found no correlation between the gamma index and the clinical impact of a discrepancy for any of the gamma index

  17. Cone Beam X-ray Luminescence Computed Tomography Based on Bayesian Method.

    Zhang, Guanglei; Liu, Fei; Liu, Jie; Luo, Jianwen; Xie, Yaoqin; Bai, Jing; Xing, Lei

    2017-01-01

    X-ray luminescence computed tomography (XLCT), which aims to achieve molecular and functional imaging by X-rays, has recently been proposed as a new imaging modality. Combining the principles of X-ray excitation of luminescence-based probes and optical signal detection, XLCT naturally fuses functional and anatomical images and provides complementary information for a wide range of applications in biomedical research. In order to improve the data acquisition efficiency of previously developed narrow-beam XLCT, a cone beam XLCT (CB-XLCT) mode is adopted here to take advantage of the useful geometric features of cone beam excitation. Practically, a major hurdle in using cone beam X-ray for XLCT is that the inverse problem here is seriously ill-conditioned, hindering us to achieve good image quality. In this paper, we propose a novel Bayesian method to tackle the bottleneck in CB-XLCT reconstruction. The method utilizes a local regularization strategy based on Gaussian Markov random field to mitigate the ill-conditioness of CB-XLCT. An alternating optimization scheme is then used to automatically calculate all the unknown hyperparameters while an iterative coordinate descent algorithm is adopted to reconstruct the image with a voxel-based closed-form solution. Results of numerical simulations and mouse experiments show that the self-adaptive Bayesian method significantly improves the CB-XLCT image quality as compared with conventional methods.

  18. Measurement of breast tissue composition with dual energy cone-beam computed tomography: A postmortem study

    Ding Huanjun; Ducote, Justin L.; Molloi, Sabee [Department of Radiological Sciences, University of California, Irvine, California 92697 (United States)

    2013-06-15

    Purpose: To investigate the feasibility of a three-material compositional measurement of water, lipid, and protein content of breast tissue with dual kVp cone-beam computed tomography (CT) for diagnostic purposes. Methods: Simulations were performed on a flat panel-based computed tomography system with a dual kVp technique in order to guide the selection of experimental acquisition parameters. The expected errors induced by using the proposed calibration materials were also estimated by simulation. Twenty pairs of postmortem breast samples were imaged with a flat-panel based dual kVp cone-beam CT system, followed by image-based material decomposition using calibration data obtained from a three-material phantom consisting of water, vegetable oil, and polyoxymethylene plastic. The tissue samples were then chemically decomposed into their respective water, lipid, and protein contents after imaging to allow direct comparison with data from dual energy decomposition. Results: Guided by results from simulation, the beam energies for the dual kVp cone-beam CT system were selected to be 50 and 120 kVp with the mean glandular dose divided equally between each exposure. The simulation also suggested that the use of polyoxymethylene as the calibration material for the measurement of pure protein may introduce an error of -11.0%. However, the tissue decomposition experiments, which employed a calibration phantom made out of water, oil, and polyoxymethylene, exhibited strong correlation with data from the chemical analysis. The average root-mean-square percentage error for water, lipid, and protein contents was 3.58% as compared with chemical analysis. Conclusions: The results of this study suggest that the water, lipid, and protein contents can be accurately measured using dual kVp cone-beam CT. The tissue compositional information may improve the sensitivity and specificity for breast cancer diagnosis.

  19. 3D Surgical Simulation

    Cevidanes, Lucia; Tucker, Scott; Styner, Martin; Kim, Hyungmin; Chapuis, Jonas; Reyes, Mauricio; Proffit, William; Turvey, Timothy; Jaskolka, Michael

    2009-01-01

    This paper discusses the development of methods for computer-aided jaw surgery. Computer-aided jaw surgery allows us to incorporate the high level of precision necessary for transferring virtual plans into the operating room. We also present a complete computer-aided surgery (CAS) system developed in close collaboration with surgeons. Surgery planning and simulation include construction of 3D surface models from Cone-beam CT (CBCT), dynamic cephalometry, semi-automatic mirroring, interactive cutting of bone and bony segment repositioning. A virtual setup can be used to manufacture positioning splints for intra-operative guidance. The system provides further intra-operative assistance with the help of a computer display showing jaw positions and 3D positioning guides updated in real-time during the surgical procedure. The CAS system aids in dealing with complex cases with benefits for the patient, with surgical practice, and for orthodontic finishing. Advanced software tools for diagnosis and treatment planning allow preparation of detailed operative plans, osteotomy repositioning, bone reconstructions, surgical resident training and assessing the difficulties of the surgical procedures prior to the surgery. CAS has the potential to make the elaboration of the surgical plan a more flexible process, increase the level of detail and accuracy of the plan, yield higher operative precision and control, and enhance documentation of cases. Supported by NIDCR DE017727, and DE018962 PMID:20816308

  20. Scatter correction, intermediate view estimation and dose characterization in megavoltage cone-beam CT imaging

    Sramek, Benjamin Koerner

    The ability to deliver conformal dose distributions in radiation therapy through intensity modulation and the potential for tumor dose escalation to improve treatment outcome has necessitated an increase in localization accuracy of inter- and intra-fractional patient geometry. Megavoltage cone-beam CT imaging using the treatment beam and onboard electronic portal imaging device is one option currently being studied for implementation in image-guided radiation therapy. However, routine clinical use is predicated upon continued improvements in image quality and patient dose delivered during acquisition. The formal statement of hypothesis for this investigation was that the conformity of planned to delivered dose distributions in image-guided radiation therapy could be further enhanced through the application of kilovoltage scatter correction and intermediate view estimation techniques to megavoltage cone-beam CT imaging, and that normalized dose measurements could be acquired and inter-compared between multiple imaging geometries. The specific aims of this investigation were to: (1) incorporate the Feldkamp, Davis and Kress filtered backprojection algorithm into a program to reconstruct a voxelized linear attenuation coefficient dataset from a set of acquired megavoltage cone-beam CT projections, (2) characterize the effects on megavoltage cone-beam CT image quality resulting from the application of Intermediate View Interpolation and Intermediate View Reprojection techniques to limited-projection datasets, (3) incorporate the Scatter and Primary Estimation from Collimator Shadows (SPECS) algorithm into megavoltage cone-beam CT image reconstruction and determine the set of SPECS parameters which maximize image quality and quantitative accuracy, and (4) evaluate the normalized axial dose distributions received during megavoltage cone-beam CT image acquisition using radiochromic film and thermoluminescent dosimeter measurements in anthropomorphic pelvic and head and

  1. Diagnostic performance of cone-beam computed tomography on detection of mechanically-created artificial secondary caries

    Charuakkra, Arnon; Prapayasatok, Sangsom; Janhom, Apirum; Pongsirwet, Surawut; Verochana, Karune; Mahasantipiya, Phattaranant [Faculty of Dentistry, Chiang Mai University, Chiang Mai (Thailand)

    2011-12-15

    The aim of this study was to compare the diagnostic accuracy of cone-beam computed tomography (CBCT) images and bitewing images in detection of secondary caries. One hundred and twenty proximal slots of Class II cavities were randomly prepared on human premolar and molar teeth, and restored with amalgam (n=60) and composite resin (n=60). Then, artificial secondary caries lesions were randomly created using round steel No. 4 bur. The teeth were radiographed with a conventional bitewing technique and two CBCT systems; Pax-500ECT and Promax 3D. All images were evaluated by five observers. The area under the receiver operating characteristic (ROC) curve (Az) was used to evaluate the diagnostic accuracy. Significant difference was tested using the Friedman test (p value<0.05). The mean Az values for bitewing, Pax-500ECT, and Promax 3D imaging systems were 0.882, 0.995, and 0.978, respectively. Significant differences were found between the two CBCT systems and film (p=0.007). For CBCT systems, the axial plane showed the greatest Az value. Based on the design of this study, CBCT images were better than bitewing radiographs in detection of secondary caries.

  2. Management of a permanent tooth after trauma to deciduous predecessor: an evaluation by cone-beam computed tomography.

    Gurgel, Carla Vecchione; Lourenço Neto, Natalino; Kobayashi, Tatiana Yuriko; Garib, Daniela Gamba; da Silva, Salete Moura Bonifácio; Machado, Maria Aparecida de Andrade Moreira; Oliveira, Thais Marchini

    2011-10-01

    Impaction of permanent teeth represents a clinical challenge with regard to diagnosis, treatment plan, and prognosis. There is a close relationship between deciduous teeth and permanent teeth germ, and any injury in the deciduous dentition may influence the permanent teeth eruption. The extent of the damage caused to the permanent teeth germ depends on the patient age at the time of injury, type of trauma, severity, and direction of the impact. Conventional radiographic images are frequently used for diagnosis; however, recent developments in three-dimensional (3D) imaging systems have enabled dentistry to visualize structural changes effectively, with better contrast and more details, close to the reality. The cone-beam computed tomography (CBCT) has been used in the diagnosis and treatment plan of these impacted teeth. The purpose of the present case report is to describe a successful conservative management of a retained permanent maxillary lateral incisor with delayed root development after a trauma through the deciduous predecessor in a 9 year-old patient. After clinical and radiographic examination, a CBCT examination of the maxilla was requested to complement the diagnosis, providing an accurate 3D position of the retained tooth and its relationship to adjacent structures. The proposed treatment plan was the surgical exposure and orthodontic traction of the retained tooth. The lateral incisor spontaneously erupted after 6 months. Therefore, this case report suggests that permanent teeth with incomplete root formation have a great potential for spontaneous eruption because no tooth malposition or mechanical obstacles are observed.

  3. pF3D Simulations of Large Outer-Beam Brillouin Scattering from NIF Rugby Hohlraums

    Langer, Steven; Strozzi, David; Chapman, Thomas; Amendt, Peter

    2015-11-01

    We assess the cause of large outer-beam stimulated Brillouin scattering (SBS) in a NIF shot with a rugby-shaped hohlraum, which has less wall surface loss and thus higher x-ray drive than a cylindrical hohlraum of the same radius. This shot differed from a prior rugby shot with low SBS in three ways: outer beam pointing, split-pointing of the four beams within each outer-beam quadruplet, and a small amount of neon added to the hohlraum helium fill gas. We use pF3D, a massively-parallel, paraxial-envelope laser plasma interaction code, with plasma profiles from the radiation-hydrodynamics code Lasnex. We determine which change between the two shots increased the SBS by adding them one at a time to the simulations. We compare the simulations to experimental data for total SBS power, its spatial distribution at the lens, and the SBS spectrum. For each shot, we use profiles from Lasnex simulations with and without a model for mix at the hohlraum wall-gas interface. Work performed under the auspices of the U.S. Department of Energy by LLNL under Contract DE-AC52-07NA27344. Release number LLNL-ABS-674893.

  4. A GPU-based finite-size pencil beam algorithm with 3D-density correction for radiotherapy dose calculation

    Gu, Xuejun; Li, Jinsheng; Jia, Xun; Jiang, Steve B

    2011-01-01

    Targeting at developing an accurate and efficient dose calculation engine for online adaptive radiotherapy, we have implemented a finite size pencil beam (FSPB) algorithm with a 3D-density correction method on GPU. This new GPU-based dose engine is built on our previously published ultrafast FSPB computational framework [Gu et al. Phys. Med. Biol. 54 6287-97, 2009]. Dosimetric evaluations against MCSIM Monte Carlo dose calculations are conducted on 10 IMRT treatment plans with heterogeneous treatment regions (5 head-and-neck cases and 5 lung cases). For head and neck cases, when cavities exist near the target, the improvement with the 3D-density correction over the conventional FSPB algorithm is significant. However, when there are high-density dental filling materials in beam paths, the improvement is small and the accuracy of the new algorithm is still unsatisfactory. On the other hand, significant improvement of dose calculation accuracy is observed in all lung cases. Especially when the target is in the m...

  5. TU-EF-207-05: Dedicated Cone-beam Breast CT

    Vedantham, S. [Univ. of Massachusetts Medical School (United States)

    2015-06-15

    mode due to lower photon fluence per projection. This may require fast-frame acquisition and symmetric or asymmetric pixel binning in some systems. Recent studies investigated the performance of increased conversion layer thickness for contrast-enhanced imaging of the breast in dual-energy acquisition mode. In other direct conversion detectors operating in the avalanche mode, sensitivities close to the single photon response are also explored for mammography and breast tomosynthesis. The potential advantages and challenges of this approach are described. Dedicated breast CT brings x-ray imaging of the breast to true tomographic 3D imaging. It can eliminate the tissue superposition problem and does not require physical compression of the breast. Using cone beam geometry and a flat-panel detector, several hundred projections are acquired and reconstructed to near isotropic voxels. Multiplanar reconstruction facilitates viewing the breast volume in any desired orientation. Ongoing clinical studies, the current state-of-the art, and research to advance the technology are described. Learning Objectives: To understand the ongoing developments in x-ray imaging of the breast To understand the approaches and applications of spectral mammography To understand the potential advantages of distributed x-ray source arrays for digital breast tomosynthesis To understand the ongoing developments in detector technology for digital mammography and breast tomosynthesis To understand the current state-of-the-art for dedicated cone-beam breast CT and research to advance the technology. Research collaboration with Koning Corporation.

  6. Improved Scatter Correction in X-Ray Cone Beam CT with Moving Beam Stop Array Using Johns' Equation

    Yan, Hao; Tang, Shaojie; Xu, Qiong

    2014-01-01

    In this paper, an improved scatter correction with moving beam stop array (BSA) for x-ray cone beam (CB) CT is proposed. Firstly, correlation between neighboring CB views is deduced based on John's Equation. Then, correlation-based algorithm is presented to complement the incomplete views by using the redundancy (over-determined information) in CB projections. Finally, combining the algorithm with scatter correction method using moving BSA, where part of primary radiation is blocked and incomplete projections are acquired, an improved correction method is proposed. Effectiveness and robustness is validated by Monte Carlo (MC) simulation with EGSnrc on humanoid phantom.

  7. 3D tracking and phase-contrast imaging by twin-beams digital holographic microscope in microfluidics

    Miccio, L.; Memmolo, P.; Finizio, A.; Paturzo, M.; Merola, F.; Grilli, S.; Ferraro, P.

    2012-06-01

    A compact twin-beam interferometer that can be adopted as a flexible diagnostic tool in microfluidic platforms is presented. The devise has two functionalities, as explained in the follow, and can be easily integrated in microfluidic chip. The configuration allows 3D tracking of micro-particles and, at same time, furnishes Quantitative Phase-Contrast maps of tracked micro-objects by interference microscopy. Experimental demonstration of its effectiveness and compatibility with biological field is given on for in vitro cells in microfluidic environment. Nowadays, several microfluidic configuration exist and many of them are commercially available, their development is due to the possibility for manipulating droplets, handling micro and nano-objects, visualize and quantify processes occurring in small volumes and, clearly, for direct applications on lab-on-a chip devices. In microfluidic research field, optical/photonics approaches are the more suitable ones because they have various advantages as to be non-contact, full-field, non-invasive and can be packaged thanks to the development of integrable optics. Moreover, phase contrast approaches, adapted to a lab-on-a-chip configurations, give the possibility to get quantitative information with remarkable lateral and vertical resolution directly in situ without the need to dye and/or kill cells. Furthermore, numerical techniques for tracking of micro-objects needs to be developed for measuring velocity fields, trajectories patterns, motility of cancer cell and so on. Here, we present a compact holographic microscope that can ensure, by the same configuration and simultaneously, accurate 3D tracking and quantitative phase-contrast analysis. The system, simple and solid, is based on twin laser beams coming from a single laser source. Through a easy conceptual design, we show how these two different functionalities can be accomplished by the same optical setup. The working principle, the optical setup and the mathematical

  8. Cone Beam CT vs. Fan Beam CT: A Comparison of Image Quality and Dose Delivered Between Two Differing CT Imaging Modalities.

    Lechuga, Lawrence; Weidlich, Georg A

    2016-09-12

    A comparison of image quality and dose delivered between two differing computed tomography (CT) imaging modalities-fan beam and cone beam-was performed. A literature review of quantitative analyses for various image quality aspects such as uniformity, signal-to-noise ratio, artifact presence, spatial resolution, modulation transfer function (MTF), and low contrast resolution was generated. With these aspects quantified, cone beam computed tomography (CBCT) shows a superior spatial resolution to that of fan beam, while fan beam shows a greater ability to produce clear and anatomically correct images with better soft tissue differentiation. The results indicate that fan beam CT produces superior images to that of on-board imaging (OBI) cone beam CT systems, while providing a considerably less dose to the patient.

  9. A simplified approach for the generation of projection data for cone beam geometry

    Tushar Roy; P S Sarkar; Amar Sinha

    2011-04-01

    To test a developed reconstruction algorithm for cone beam geometry, whether it is transmission or emission tomography, one needs projection data. Generally, mathematical phantoms are generated in three dimensions and the projection for all rotation angles is calculated. For non-symmetric objects, the process is cumbersome and computation intensive. This paper describes a simple methodology for the generation of projection data for cone beam geometry for both transmission and emission tomographies by knowing the object’s attenuation and/or source spatial distribution details as input. The object details such as internal geometrical distribution are nowhere involved in the projection data calculation. This simple approach uses the pixilated object matrix values in terms of the matrix indices and spatial geometrical coordinates. The projection data of some typical phantoms (generated using this approach) are reconstructed using standard FDK algorithm and Novikov’s inversion formula. Correlation between the original and reconstructed images has been calculated to compare the image quality.

  10. MR cone-beam CT fusion image overlay for fluoroscopically guided percutaneous biopsies in pediatric patients.

    Thakor, Avnesh S; Patel, Premal A; Gu, Richard; Rea, Vanessa; Amaral, Joao; Connolly, Bairbre L

    2016-03-01

    Lesions only visible on magnetic resonance (MR) imaging cannot easily be targeted for image-guided biopsy using ultrasound or X-rays but instead require MR guidance with MR-compatible needles and long procedure times (acquisition of multiple MR sequences). We developed an alternative method for performing these difficult biopsies in a standard interventional suite, by fusing MR with cone-beam CT images. The MR cone-beam CT fusion image is then used as an overlay to guide a biopsy needle to the target area under live fluoroscopic guidance. Advantages of this technique include (i) the ability for it to be performed in a conventional interventional suite, (ii) three-dimensional planning of the needle trajectory using cross-sectional imaging, (iii) real-time fluoroscopic guidance for needle trajectory correction and (iv) targeting within heterogeneous lesions based on MR signal characteristics to maximize the potential biopsy yield.

  11. Cone-Beam Computed Tomography Evaluation of Mental Foramen Variations: A Preliminary Study

    Mahnaz Sheikhi

    2015-01-01

    Full Text Available Background. Mental foramen is important in surgical operations of premolars because it transfers the mental nerves and vessels. This study evaluated the variations of mental foramen by cone-beam computed tomography among a selected Iranian population. Materials and Methods. A total number of 180 cone-beam computed tomography projections were analyzed in terms of shape, size, direction, and horizontal and vertical positions of mental foramen in the right and left sides. Results. The most common shape was oval, opening direction was posterior-superior, horizontal position was in line with second premolar, and vertical position was apical to the adjacent dental root. The mean of foremen diameter was 3.59 mm. Conclusion. In addition to the most common types of mental foramen, other variations exist, too. Hence, it reflects the significance of preoperative radiographic examinations, especially 3-dimensional images to prevent nerve damage.

  12. Novel information theory based method for superimposition of lateral head radiographs and cone beam computed tomography images

    Jacquet, W; Nyssen, E; Bottenberg, P; de Groen, P; Vande Vannet, B

    2010-01-01

    Objectives The aim was to introduce a novel alignment criterion, focus mutual information (FMI), for the superimposition of lateral cephalometric radiographs and three dimensional (3D) cone beam computed images as well as the assessment of the alignment characteristics of the new method and comparison of the novel methodology with the region of interest (ROI) approach. Methods Implementation of a FMI criterion-based methodology that only requires the approximate indication of stable structures in one single image. The robustness of the method was first addressed in a phantom experiment comparing the new technique with a ROI approach. Two consecutive cephalometric radiographs were then obtained, one before and one after functional twin block application. These images were then superimposed using alignment by FMI where the following were focused on, in several ways: (1) cranial base and acoustic meatus, (2) palatal plane and (3) mandibular symphysis. The superimposed images were subtracted and coloured. The applicability to cone beam CT (CBCT) is illustrated by the alignment of CBCT images acquired before and after craniofacial surgery. Results The phantom experiment clearly shows superior alignment when compared to the ROI approach (Wilcoxon n = 17, Z = −3.290, and P = 0.001), and robustness with respect to the choice of parameters (one-sample t-test n = 50, t = −12.355, and P = 0.000). The treatment effects are revealed clearly in the subtraction image of well-aligned cephalometric radiographs. The colouring scheme of the subtraction image emphasises the areas of change and visualizes the remodelling of the soft tissue. Conclusions FMI allows for cephalometry without tracing, it avoids the error inherent to the use of landmarks and the interaction of the practitioner is kept to a minimum. The robustness to focal distribution variations limits the influence of possible examiner inaccuracy. PMID:20395459

  13. Fast spatial beam shaping by acousto-optic diffraction for 3D non-linear microscopy.

    Akemann, Walther; Léger, Jean-François; Ventalon, Cathie; Mathieu, Benjamin; Dieudonné, Stéphane; Bourdieu, Laurent

    2015-11-01

    Acousto-optic deflection (AOD) devices offer unprecedented fast control of the entire spatial structure of light beams, most notably their phase. AOD light modulation of ultra-short laser pulses, however, is not straightforward to implement because of intrinsic chromatic dispersion and non-stationarity of acousto-optic diffraction. While schemes exist to compensate chromatic dispersion, non-stationarity remains an obstacle. In this work we demonstrate an efficient AOD light modulator for stable phase modulation using time-locked generation of frequency-modulated acoustic waves at the full repetition rate of a high power laser pulse amplifier of 80 kHz. We establish the non-local relationship between the optical phase and the generating acoustic frequency function and verify the system for temporal stability, phase accuracy and generation of non-linear two-dimensional phase functions.

  14. Fast and Precise 3D Computation of Capacitance of Parallel Narrow Beam MEMS Structures

    Majumdar, N

    2007-01-01

    Efficient design and performance of electrically actuated MEMS devices necessitate accurate estimation of electrostatic forces on the MEMS structures. This in turn requires thorough study of the capacitance of the structures and finally the charge density distribution on the various surfaces of a device. In this work, nearly exact BEM solutions have been provided in order to estimate these properties of a parallel narrow beam structure found in MEMS devices. The effect of three-dimensionality, which is an important aspect for these structures, and associated fringe fields have been studied in detail. A reasonably large parameter space has been covered in order to follow the variation of capacitance with various geometric factors. The present results have been compared with those obtained using empirical parametrized expressions keeping in view the requirement of the speed of computation. The limitations of the empirical expressions have been pointed out and possible approaches of their improvement have been d...

  15. FPGA architectures for electronically scanned wide-band RF beams using 3-D FIR/IIR digital filters for rectangular array aperture receivers

    Wijayaratna, Sewwandi; Madanayake, Arjuna; Beall, Brandon D.; Bruton, Len T.

    2014-05-01

    Real-time digital implementation of three-dimensional (3-D) infinite impulse response (IIR) beam filters are discussed. The 3-D IIR filter building blocks have filter coefficients, which are defined using algebraic closed-form expressions that are functions of desired beam personalities, such as the look-direction of the aperture, the bandwidth and sampling frequency of interest, inter antenna spacing, and 3dB beam size. Real-time steering of such 3-D beam filters are obtained by proposed calculation of filter coefficients. Application specific computing units for rapidly calculating the 3-D IIR filter coefficients at nanosecond speed potentially allows fast real-time tracking of low radar cross section (RCS) objects at close range. Proposed design consists of 3-D IIR beam filter with 4 4 antenna grid and the filter coefficient generation block in separate FPGAs. The hardware is designed and co-simulated using a Xilinx Virtex-6 XC6VLX240T FPGA. The 3-D filter operates over 90 MHz and filter coefficient computing structure can operate at up to 145 MHz.

  16. SADMFR guidelines for the use of cone-beam computed tomography/ Digital Volume Tomography

    Dula, Karl; Bornstein, Michael M.; Buser, Daniel; Dagassan-Berndt, Dorothea; Ettlin, Dominik A; Filippi, Andreas; Gabioud, François; Katsaros, Christos; Krastl, Gabriel; Lambrecht, J. Thomas; Lauber, Roland; Luebbers, Heinz-Theo; Pazera, Pawel; Türp, Jens C.

    2014-01-01

    Cone-Beam Computed Tomography (CBCT) has been introduced in 1998. This radiological imaging procedure has been provided for dentistry and is comparable to computed tomography (CT) in medicine. It is expected that CBCT will have the same success in dental diagnostic imaging as computed tomography had in medicine. Just as CT is responsible for a significant rise in radiation dose to the population from medical X-ray diagnostics, CBCT studies will be accompanied by a significant increase of the ...

  17. Dental implants in bilateral bifid canal and compromised interocclusal space using cone beam computerized tomography

    Ahmed, Nizar; Arunachalam, Lalitha Tanjore; Jacob, Caroline Annette; Kumar, Suresh Anand

    2016-01-01

    Knowledge of various anatomic landmarks is pivotal for important success. Bifid canals pose a challenge and can lead to difficulties while performing implant surgery in the mandible. Bifid canals can be diagnosed with panoramic radiography and more accurately with cone beam computerized tomography (CBCT). This case report details the placement of the implant in a patient with bilateral bifid canal and compromised interocclusal space, which was successfully treated using CBCT. PMID:27433073

  18. History of imaging in orthodontics from Broadbent to cone-beam computed tomography.

    Hans, Mark G; Palomo, J Martin; Valiathan, Manish

    2015-12-01

    The history of imaging and orthodontics is a story of technology informing biology. Advances in imaging changed our thinking as our understanding of craniofacial growth and the impact of orthodontic treatment deepened. This article traces the history of imaging in orthodontics from the invention of the cephalometer by B. Holly Broadbent in 1930 to the introduction of low-cost, low-radiation-dose cone-beam computed tomography imaging in 2015.

  19. Impact of cone-beam computed tomography on implant planning and on prediction of implant size

    Ludmila Assunção de Mello Pedroso; Robson Rodrigues Garcia; José Luiz Rodrigues Leles; Cláudio Rodrigues Leles; Maria Alves Garcia Santos Silva

    2014-01-01

    The aim was to investigate the impact of cone-beam computed tomography (CBCT) on implant planning and on prediction of final implant size. Consecutive patients referred for implant treatment were submitted to clinical examination, panoramic (PAN) radiography and a CBCT exam. Initial planning of implant length and width was assessed based on clinical and PAN exams, and final planning, on CBCT exam to complement diagnosis. The actual dimensions of the implants placed during surgery were compare...

  20. Diagnostic accuracy of cone beam computed tomography in detection of simulated mandibular condyle erosions

    Shahriar Shahab; Nafiseh Nikkerdar; Maryam Goodarzi; Amin Golshah; Sanaz Sharifi Shooshtari

    2015-01-01

    Introduction: To determine the diagnostic accuracy of cone beam computed tomography (CBCT) in the detection of simulated mandibular condyle erosions. Materials and Methods: Seventeen dry human mandibles were used in this in vitro study. NewTom VG CBCT scanner (New Tom VG, Verona, Veneto region, Italy) was used for the condyles imaging (pre-erosion and post-erosion image). Thirty three lesions were created on the superior (11 cases), anterior (11 cases), and posterior surfaces (11 cases) o...

  1. Assessment of optimal condylar position with cone-beam computed tomography in south Indian female population

    Manjula, W. S.; Faizal Tajir; R.V. Murali; Kishore Kumar, S; Mohammed Nizam

    2015-01-01

    Aim: The purpose of this study was to investigate, the condyle-fossa relationship, in clinically asymptomatic orthodontically untreated south Indian female volunteers, by cone-beam computed tomography (CBCT). Materials and Methods: The study population consisted of 13 clinically symptom-free and orthodontically untreated angle's Class I female subjects with the mean age of 18 years (ranges from 17 years to 20 years). The normal disc position of the 13 subjects was confirmed by history, clinic...

  2. X-Ray Scatter Correction on Soft Tissue Images for Portable Cone Beam CT

    Sorapong Aootaphao; Saowapak S. Thongvigitmanee; Jartuwat Rajruangrabin; Chalinee Thanasupsombat; Tanapon Srivongsa; Pairash Thajchayapong

    2016-01-01

    Soft tissue images from portable cone beam computed tomography (CBCT) scanners can be used for diagnosis and detection of tumor, cancer, intracerebral hemorrhage, and so forth. Due to large field of view, X-ray scattering which is the main cause of artifacts degrades image quality, such as cupping artifacts, CT number inaccuracy, and low contrast, especially on soft tissue images. In this work, we propose the X-ray scatter correction method for improving soft tissue images. The X-ray scatter ...

  3. Quantification of organ motion during chemoradiotherapy of rectal cancer using cone-beam computed tomography.

    Chong, Irene

    2011-11-15

    There has been no previously published data related to the quantification of rectal motion using cone-beam computed tomography (CBCT) during standard conformal long-course chemoradiotherapy. The purpose of the present study was to quantify the interfractional changes in rectal movement and dimensions and rectal and bladder volume using CBCT and to quantify the bony anatomy displacements to calculate the margins required to account for systematic (Σ) and random (σ) setup errors.

  4. Maxillary first molars with six canals confirmed with the aid of cone-beam computed tomography

    Tahra Mohammad Al-Habboubi

    2016-01-01

    Full Text Available The maxillary first molar exhibits unpredictable root canal morphology. Different number of root canals has been reported with the aids of new tools. It is very important to clinically detect all canals for better outcome results. The purpose of the present case is to present a case of the maxillary first molar in a Saudi male patient with an anatomical variation of having six root canals that were confirmed with cone-beam computed tomography.

  5. The effect of cone beam CT (CBCT) on therapeutic decision-making in endodontics

    Mota de Almeida, F J; Knutsson, K.; Flygare, Lennart

    2014-01-01

    Objectives: The aim was to assess to what extent cone beam CT (CBCT) used in accordance with current European Commission guidelines in a normal clinical setting has an impact on therapeutic decisions in a population referred for endodontic problems. Methods: The study includes data of consecutively examined patients collected from October 2011 to December 2012. From 2 different endodontic specialist clinics, 57 patients were referred for a CBCT examination using criteria in accordance with cu...

  6. Assessment of bifid and trifid mandibular canals using cone-beam computed tomography

    2014-01-01

    Purpose To investigate the prevalence of bifid and trifid mandibular canals using cone-beam computed tomography (CBCT) images, and to measure their length, diameter, and angle. Materials and Methods CBCT images of 500 patients, involving 755 hemi-mandibles, were used for this study. The presence and type of bifid mandibular canal was evaluated according to a modified classification of Naitoh et al. Prevalence rates were determined according to age group, gender, and type. Further, their diame...

  7. SPECT reconstruction of combined cone beam and parallel hole collimation with experimental data

    Li, Jianying; Jaszczak, Ronald J.; Turkington, Timothy G.; Greer, Kim L.; Coleman, R. Edward

    1993-06-01

    We have developed three methods to combine parallel and cone beam (P & CB) SPECT data using modified Maximum Likelihood-Expectation Maximization (ML-EM) algorithms. The first combination method applies both parallel and cone beam data sets to reconstruct a single intermediate image after each iteration using the ML-EL algorithm. The other two iterative methods combine the intermediate beam (PB) and cone (CB) source estimates to enhance the uniformity of images. These two methods are ad hoc methods. In earlier studies using computer Monte Carlo simulation, we suggested that improved images might be obtained by reconstructing combined P & CB SPECT data. These combined collimation methods are qualitatively evaluated using experimental data. An attenuation compensation is performed by including the effects of attenuation in the transition matrix as a multiplicative factor. The combined P&CB images are compared with CB-only images and the results indicate that the combined P&CB approaches suppress artifacts caused by truncated projections and correct for the distortions of the CB-only images.

  8. Accuracy of measurements of mandibular anatomy in cone beam computed tomography images

    Ludlow, John B.; Laster, William Stewart; See, Meit; Bailey, L’Tanya J.; Hershey, H. Garland

    2013-01-01

    Objectives Cone beam computed tomography (CBCT) images of ideally positioned and systematically mispositioned dry skulls were measured using two-dimensional and three-dimensional software measurement techniques. Image measurements were compared with caliper measurements of the skulls. Study design Cone beam computed tomography volumes of 28 skulls in ideal, shifted, and rotated positions were assessed by measuring distances between anatomic points and reference wires by using panoramic reconstructions (two-dimensional) and direct measurements from axial slices (three-dimensional). Differences between caliper measurements on skulls and software measurements in images were assessed with paired t tests and analysis of variance (ANOVA). Results Accuracy of measurement was not significantly affected by alterations in skull position or measurement of right or left sides. For easily visualized orthodontic wires, measurement accuracy was expressed by average errors less than 1.2% for two-dimensional measurement techniques and less than 0.6% for three-dimensional measurement techniques. Anatomic measurements were significantly more variable regardless of measurement technique. Conclusions Both two-dimensional and three-dimensional techniques provide acceptably accurate measurement of mandibular anatomy. Cone beam computed tomography measurement was not significantly influenced by variation in skull orientation during image acquisition. PMID:17395068

  9. Correction of patient positioning errors based on in-line cone beam CTs: clinical implementation and first experiences

    Häring Peter

    2006-05-01

    Full Text Available Abstract Background The purpose of the study was the clinical implementation of a kV cone beam CT (CBCT for setup correction in radiotherapy. Patients and methods For evaluation of the setup correction workflow, six tumor patients (lung cancer, sacral chordoma, head-and-neck and paraspinal tumor, and two prostate cancer patients were selected. All patients were treated with fractionated stereotactic radiotherapy, five of them with intensity modulated radiotherapy (IMRT. For patient fixation, a scotch cast body frame or a vacuum pillow, each in combination with a scotch cast head mask, were used. The imaging equipment, consisting of an x-ray tube and a flat panel imager (FPI, was attached to a Siemens linear accelerator according to the in-line approach, i.e. with the imaging beam mounted opposite to the treatment beam sharing the same isocenter. For dose delivery, the treatment beam has to traverse the FPI which is mounted in the accessory tray below the multi-leaf collimator. For each patient, a predefined number of imaging projections over a range of at least 200 degrees were acquired. The fast reconstruction of the 3D-CBCT dataset was done with an implementation of the Feldkamp-David-Kress (FDK algorithm. For the registration of the treatment planning CT with the acquired CBCT, an automatic mutual information matcher and manual matching was used. Results and discussion Bony landmarks were easily detected and the table shifts for correction of setup deviations could be automatically calculated in all cases. The image quality was sufficient for a visual comparison of the desired target point with the isocenter visible on the CBCT. Soft tissue contrast was problematic for the prostate of an obese patient, but good in the lung tumor case. The detected maximum setup deviation was 3 mm for patients fixated with the body frame, and 6 mm for patients positioned in the vacuum pillow. Using an action level of 2 mm translational error, a target point

  10. Use of cone beam computed tomography in implant dentistry: current concepts, indications and limitations for clinical practice and research.

    Bornstein, Michael M; Horner, Keith; Jacobs, Reinhilde

    2017-02-01

    Diagnostic radiology is an essential component of treatment planning in the field of implant dentistry. This narrative review will present current concepts for the use of cone beam computed tomography imaging, before and after implant placement, in daily clinical practice and research. Guidelines for the selection of three-dimensional imaging will be discussed, and limitations will be highlighted. Current concepts of radiation dose optimization, including novel imaging modalities using low-dose protocols, will be presented. For preoperative cross-sectional imaging, data are still not available which demonstrate that cone beam computed tomography results in fewer intraoperative complications such as nerve damage or bleeding incidents, or that implants inserted using preoperative cone beam computed tomography data sets for planning purposes will exhibit higher survival or success rates. The use of cone beam computed tomography following the insertion of dental implants should be restricted to specific postoperative complications, such as damage of neurovascular structures or postoperative infections in relation to the maxillary sinus. Regarding peri-implantitis, the diagnosis and severity of the disease should be evaluated primarily based on clinical parameters and on radiological findings based on periapical radiographs (two dimensional). The use of cone beam computed tomography scans in clinical research might not yield any evident beneficial effect for the patient included. As many of the cone beam computed tomography scans performed for research have no direct therapeutic consequence, dose optimization measures should be implemented by using appropriate exposure parameters and by reducing the field of view to the actual region of interest.

  11. A surgical navigation system for non-contact diffuse optical tomography and intraoperative cone-beam CT

    Daly, Michael J.; Muhanna, Nidal; Chan, Harley; Wilson, Brian C.; Irish, Jonathan C.; Jaffray, David A.

    2014-02-01

    A freehand, non-contact diffuse optical tomography (DOT) system has been developed for multimodal imaging with intraoperative cone-beam CT (CBCT) during minimally-invasive cancer surgery. The DOT system is configured for near-infrared fluorescence imaging with indocyanine green (ICG) using a collimated 780 nm laser diode and a nearinfrared CCD camera (PCO Pixelfly USB). Depending on the intended surgical application, the camera is coupled to either a rigid 10 mm diameter endoscope (Karl Storz) or a 25 mm focal length lens (Edmund Optics). A prototype flatpanel CBCT C-Arm (Siemens Healthcare) acquires low-dose 3D images with sub-mm spatial resolution. A 3D mesh is extracted from CBCT for finite-element DOT implementation in NIRFAST (Dartmouth College), with the capability for soft/hard imaging priors (e.g., segmented lymph nodes). A stereoscopic optical camera (NDI Polaris) provides real-time 6D localization of reflective spheres mounted to the laser and camera. Camera calibration combined with tracking data is used to estimate intrinsic (focal length, principal point, non-linear distortion) and extrinsic (translation, rotation) lens parameters. Source/detector boundary data is computed from the tracked laser/camera positions using radiometry models. Target registration errors (TRE) between real and projected boundary points are ~1-2 mm for typical acquisition geometries. Pre-clinical studies using tissue phantoms are presented to characterize 3D imaging performance. This translational research system is under investigation for clinical applications in head-and-neck surgery including oral cavity tumour resection, lymph node mapping, and free-flap perforator assessment.

  12. Deformable image registration for cone-beam CT guided transoral robotic base-of-tongue surgery

    Reaungamornrat, S.; Liu, W. P.; Wang, A. S.; Otake, Y.; Nithiananthan, S.; Uneri, A.; Schafer, S.; Tryggestad, E.; Richmon, J.; Sorger, J. M.; Siewerdsen, J. H.; Taylor, R. H.

    2013-07-01

    Transoral robotic surgery (TORS) offers a minimally invasive approach to resection of base-of-tongue tumors. However, precise localization of the surgical target and adjacent critical structures can be challenged by the highly deformed intraoperative setup. We propose a deformable registration method using intraoperative cone-beam computed tomography (CBCT) to accurately align preoperative CT or MR images with the intraoperative scene. The registration method combines a Gaussian mixture (GM) model followed by a variation of the Demons algorithm. First, following segmentation of the volume of interest (i.e. volume of the tongue extending to the hyoid), a GM model is applied to surface point clouds for rigid initialization (GM rigid) followed by nonrigid deformation (GM nonrigid). Second, the registration is refined using the Demons algorithm applied to distance map transforms of the (GM-registered) preoperative image and intraoperative CBCT. Performance was evaluated in repeat cadaver studies (25 image pairs) in terms of target registration error (TRE), entropy correlation coefficient (ECC) and normalized pointwise mutual information (NPMI). Retraction of the tongue in the TORS operative setup induced gross deformation >30 mm. The mean TRE following the GM rigid, GM nonrigid and Demons steps was 4.6, 2.1 and 1.7 mm, respectively. The respective ECC was 0.57, 0.70 and 0.73, and NPMI was 0.46, 0.57 and 0.60. Registration accuracy was best across the superior aspect of the tongue and in proximity to the hyoid (by virtue of GM registration of surface points on these structures). The Demons step refined registration primarily in deeper portions of the tongue further from the surface and hyoid bone. Since the method does not use image intensities directly, it is suitable to multi-modality registration of preoperative CT or MR with intraoperative CBCT. Extending the 3D image registration to the fusion of image and planning data in stereo-endoscopic video is anticipated to

  13. Self-calibration of cone-beam CT geometry using 3D–2D image registration

    Ouadah, S; Stayman, J W; Gang, G J; Ehtiati, T; Siewerdsen, J H

    2016-01-01

    Robotic C-arms are capable of complex orbits that can increase field of view, reduce artifacts, improve image quality, and/or reduce dose; however, it can be challenging to obtain accurate, reproducible geometric calibration required for image reconstruction for such complex orbits. This work presents a method for geometric calibration for an arbitrary source-detector orbit by registering 2D projection data to a previously acquired 3D image. It also yields a method by which calibration of simple circular orbits can be improved. The registration uses a normalized gradient information similarity metric and the covariance matrix adaptation-evolution strategy optimizer for robustness against local minima and changes in image content. The resulting transformation provides a ‘self-calibration’ of system geometry. The algorithm was tested in phantom studies using both a cone-beam CT (CBCT) test-bench and a robotic C-arm (Artis Zeego, Siemens Healthcare) for circular and non-circular orbits. Self-calibration performance was evaluated in terms of the full-width at half-maximum (FWHM) of the point spread function in CBCT reconstructions, the reprojection error (RPE) of steel ball bearings placed on each phantom, and the overall quality and presence of artifacts in CBCT images. In all cases, self-calibration improved the FWHM—e.g. on the CBCT bench, FWHM = 0.86 mm for conventional calibration compared to 0.65 mm for self-calibration (p < 0.001). Similar improvements were measured in RPE—e.g. on the robotic C-arm, RPE = 0.73 mm for conventional calibration compared to 0.55 mm for self-calibration (p < 0.001). Visible improvement was evident in CBCT reconstructions using self-calibration, particularly about high-contrast, high-frequency objects (e.g. temporal bone air cells and a surgical needle). The results indicate that self-calibration can improve even upon systems with presumably accurate geometric calibration and is applicable to situations where conventional

  14. Linac-integrated 4D cone beam CT: first experimental results

    Dietrich, Lars; Jetter, Siri; Tücking, Thomas; Nill, Simeon; Oelfke, Uwe

    2006-06-01

    A new online imaging approach, linac-integrated cone beam CT (CBCT), has been developed over the past few years. It has the advantage that a patient can be examined in their treatment position directly before or during a radiotherapy treatment. Unfortunately, respiratory organ motion, one of the largest intrafractional organ motions, often leads to artefacts in the reconstructed 3D images. One way to take this into account is to register the breathing phase during image acquisition for a phase-correlated image reconstruction. Therefore, the main focus of this work is to present a system which has the potential to investigate the correlation between internal (movement of the diaphragm) and external (data of a respiratory gating system) information about breathing phase and amplitude using an inline CBCT scanner. This also includes a feasibility study about using the acquired information for a respiratory-correlated 4D CBCT reconstruction. First, a moving lung phantom was used to develop and to specify the required methods which are based on an image reconstruction using only projections belonging to a certain moving phase. For that purpose, the corresponding phase has to be detected for each projection. In the case of the phantom, an electrical signal allows one to track the movement in real time. The number of projections available for the image reconstruction depends on the breathing phase and the size of the position range from which projections should be used for the reconstruction. The narrower this range is, the better the inner structures can be located, but also the noise of the images increases due to the limited number of projections. This correlation has also been analysed. In a second step, the methods were clinically applied using data sets of patients with lung tumours. In this case, the breathing phase was detected by an external gating system (AZ-733V, Anzai Medical Co.) based on a pressure sensor attached to the patient's abdominal region with a

  15. Cone Beam CT vs. Fan Beam CT: A Comparison of Image Quality and Dose Delivered Between Two Differing CT Imaging Modalities

    Weidlich, Georg A.

    2016-01-01

    A comparison of image quality and dose delivered between two differing computed tomography (CT) imaging modalities—fan beam and cone beam—was performed. A literature review of quantitative analyses for various image quality aspects such as uniformity, signal-to-noise ratio, artifact presence, spatial resolution, modulation transfer function (MTF), and low contrast resolution was generated. With these aspects quantified, cone beam computed tomography (CBCT) shows a superior spatial resolution to that of fan beam, while fan beam shows a greater ability to produce clear and anatomically correct images with better soft tissue differentiation. The results indicate that fan beam CT produces superior images to that of on-board imaging (OBI) cone beam CT systems, while providing a considerably less dose to the patient. PMID:27752404

  16. A novel region-growing based semi-automatic segmentation protocol for three-dimensional condylar reconstruction using cone beam computed tomography (CBCT.

    Tong Xi

    Full Text Available OBJECTIVE: To present and validate a semi-automatic segmentation protocol to enable an accurate 3D reconstruction of the mandibular condyles using cone beam computed tomography (CBCT. MATERIALS AND METHODS: Approval from the regional medical ethics review board was obtained for this study. Bilateral mandibular condyles in ten CBCT datasets of patients were segmented using the currently proposed semi-automatic segmentation protocol. This segmentation protocol combined 3D region-growing and local thresholding algorithms. The segmentation of a total of twenty condyles was performed by two observers. The Dice-coefficient and distance map calculations were used to evaluate the accuracy and reproducibility of the segmented and 3D rendered condyles. RESULTS: The mean inter-observer Dice-coefficient was 0.98 (range [0.95-0.99]. An average 90th percentile distance of 0.32 mm was found, indicating an excellent inter-observer similarity of the segmented and 3D rendered condyles. No systematic errors were observed in the currently proposed segmentation protocol. CONCLUSION: The novel semi-automated segmentation protocol is an accurate and reproducible tool to segment and render condyles in 3D. The implementation of this protocol in the clinical practice allows the CBCT to be used as an imaging modality for the quantitative analysis of condylar morphology.

  17. Investigation of beam deflection reduction and multi-beamlet focus at a large-area negative ion source for a neutral beam injector with 3-D beam trajectory simulation

    Tanaka, M; Asano, E; Oka, Y; Osakabe, M; Tsumori, K; Kaneko, O; Yamashita, Y

    2000-01-01

    We investigated the reduction of ion beam deflection caused by electron deflection magnets, and focus of multi-beamlets at a large-area negative ion source of a neutral beam injector (NBI) in order to reduce beam loss during long-distance beam transport (>10 m) and beam injection into a nuclear fusion device. The electrostatic lens effect by displacement of the beam extraction aperture of a grounded grid (GG) was utilized for the beam deflection reduction and the multi-beamlet focus. We proposed an analysis process to adjust the aperture displacement which avoids beam collision with the GG by too much displacement. The analysis process includes a 3-D beam trajectory simulation used for analyzing the beam deflection angle and beam radius as well as theoretical calculations, which are used to calculate the aperture displacement based on the 3-D simulation results. Applicability of the analysis process was examined for a large-area high-current H sup - ion source of an NBI (0.25 mx1.25 m, 40 A, 180 keV). The ana...

  18. Robust methods for automatic image-to-world registration in cone-beam CT interventional guidance

    Dang, H.; Otake, Y.; Schafer, S.; Stayman, J. W.; Kleinszig, G.; Siewerdsen, J. H. [Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland 21202 (United States); Siemens Healthcare XP Division, Erlangen 91052 (Germany); Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland 21202 (United States)

    2012-10-15

    Purpose: Real-time surgical navigation relies on accurate image-to-world registration to align the coordinate systems of the image and patient. Conventional manual registration can present a workflow bottleneck and is prone to manual error and intraoperator variability. This work reports alternative means of automatic image-to-world registration, each method involving an automatic registration marker (ARM) used in conjunction with C-arm cone-beam CT (CBCT). The first involves a Known-Model registration method in which the ARM is a predefined tool, and the second is a Free-Form method in which the ARM is freely configurable. Methods: Studies were performed using a prototype C-arm for CBCT and a surgical tracking system. A simple ARM was designed with markers comprising a tungsten sphere within infrared reflectors to permit detection of markers in both x-ray projections and by an infrared tracker. The Known-Model method exercised a predefined specification of the ARM in combination with 3D-2D registration to estimate the transformation that yields the optimal match between forward projection of the ARM and the measured projection images. The Free-Form method localizes markers individually in projection data by a robust Hough transform approach extended from previous work, backprojected to 3D image coordinates based on C-arm geometric calibration. Image-domain point sets were transformed to world coordinates by rigid-body point-based registration. The robustness and registration accuracy of each method was tested in comparison to manual registration across a range of body sites (head, thorax, and abdomen) of interest in CBCT-guided surgery, including cases with interventional tools in the radiographic scene. Results: The automatic methods exhibited similar target registration error (TRE) and were comparable or superior to manual registration for placement of the ARM within {approx}200 mm of C-arm isocenter. Marker localization in projection data was robust across all

  19. TU-AB-204-00: Advances in Cone-Beam CT and Emerging Applications

    NONE

    2015-06-15

    This symposium highlights advanced cone-beam CT (CBCT) technologies in four areas of emerging application in diagnostic imaging and image-guided interventions. Each area includes research that extends the spatial, temporal, and/or contrast resolution characteristics of CBCT beyond conventional limits through advances in scanner technology, acquisition protocols, and 3D image reconstruction techniques. Dr. G. Chen (University of Wisconsin) will present on the topic: Advances in C-arm CBCT for Brain Perfusion Imaging. Stroke is a leading cause of death and disability, and a fraction of people having an acute ischemic stroke are suitable candidates for endovascular therapy. Critical factors that affect both the likelihood of successful revascularization and good clinical outcome are: 1) the time between stroke onset and revascularization; and 2) the ability to distinguish patients who have a small volume of irreversibly injured brain (ischemic core) and a large volume of ischemic but salvageable brain (penumbra) from patients with a large ischemic core and little or no penumbra. Therefore, “time is brain” in the care of the stroke patients. C-arm CBCT systems widely available in angiography suites have the potential to generate non-contrast-enhanced CBCT images to exclude the presence of hemorrhage, time-resolved CBCT angiography to evaluate the site of occlusion and collaterals, and CBCT perfusion parametric images to assess the extent of the ischemic core and penumbra, thereby fulfilling the imaging requirements of a “one-stop-shop” in the angiography suite to reduce the time between onset and revascularization therapy. The challenges and opportunities to advance CBCT technology to fully enable the one-stop-shop C-arm CBCT platform for brain imaging will be discussed. Dr. R. Fahrig (Stanford University) will present on the topic: Advances in C-arm CBCT for Cardiac Interventions. With the goal of providing functional information during cardiac interventions

  20. Maxillary first molar with 7 root canals diagnosed using cone-beam computed tomography

    Rodrigues, Evaldo; Braitt, Antônio Henrique; Galvão, Bruno Ferraz

    2017-01-01

    Root canal anatomy is complex, and the recognition of anatomic variations could be a challenge for clinicians. This case report describes the importance of cone beam computed tomographyic (CBCT) imaging during endodontic treatment. A 23 year old woman was referred by her general dental practitioner with the chief complaint of spontaneous pain in her right posterior maxilla. From the clinical and radiographic findings, a diagnosis of symptomatic irreversible pulpitis was made and endodontic treatment was suggested to the patient. The patient underwent CBCT examination, and CBCT scan slices revealed seven canals: three mesiobuccal (MB1, MB2, and MB3), two distobuccal (DB1 and DB2), and two palatal (P1 and P2). Canals were successfully treated with reciprocating files and filled using single-cone filling technique. Precise knowledge of root canal morphology and its variation is important during root canal treatment. CBCT examination is an excellent tool for identifying and managing these complex root canal systems.

  1. Three-Dimensional Reconstruction from Cone-Beam Projections for Flat and Curved Detectors: Reconstruction Method Development.

    Hu, Hui

    This dissertation is principally concerned with improving the performance of a prototype image-intensifier -based cone-beam volume computed tomography system by removing or partially removing two of its restricting factors, namely, the inaccuracy of current cone-beam reconstruction algorithm and the image distortion associated with the curved detecting surface of the image intensifier. To improve the accuracy of cone-beam reconstruction, first, the currently most accurate and computationally efficient cone-beam reconstruction method, the Feldkamp algorithm, is investigated by studying the relation of an original unknown function with its Feldkamp estimate. From this study, a partial knowledge on the unknown function can be derived in the Fourier domain from its Feldkamp estimate. Then, based on the Gerchberg-Papoulis algorithm, a modified iterative algorithm efficiently incorporating the Fourier knowledge as well as the a priori spatial knowledge on the unknown function is devised and tested to improve the cone-beam reconstruction accuracy by postprocessing the Feldkamp estimate. Two methods are developed to remove the distortion associated with the curved surface of image intensifier. A calibrating method based on a rubber-sheet remapping is designed and implemented. As an alternative, the curvature can be considered in the reconstruction algorithm. As an initial effort along this direction, a generalized convolution -backprojection reconstruction algorithm for fan-beam and any circular detector arrays is derived and studied.

  2. 3D Prior Image Constrained Projection Completion for X-ray CT Metal Artifact Reduction

    Mehranian, Abolfazl; Ay, Mohammad Reza; Rahmim, Arman; Zaidi, Habib

    2013-01-01

    The presence of metallic implants in the body of patients undergoing X-ray computed tomography (CT) examinations often results insevere streaking artifacts that degrade image quality. In this work, we propose a new metal artifact reduction (MAR) algorithm for 2D fan-beam and 3D cone-beam CT based on

  3. Scattering-compensated cone beam x-ray luminescence computed tomography

    Gao, Peng; Rong, Junyan; Pu, Huangsheng; Liu, Wenlei; Liao, Qimei; Lu, Hongbing

    2016-04-01

    X-ray luminescence computed tomography (XLCT) opens new possibilities to perform molecular imaging with x-ray. It is a dual modality imaging technique based on the principle that some nanophosphors can emit near-infrared (NIR) light when excited by x-rays. The x-ray scattering effect is a great issue in both CT and XLCT reconstruction. It has been shown that if the scattering effect compensated, the reconstruction average relative error can be reduced from 40% to 12% in the in the pencil beam XLCT. However, the scattering effect in the cone beam XLCT has not been proved. To verify and reduce the scattering effect, we proposed scattering-compensated cone beam x-ray luminescence computed tomography using an added leading to prevent the spare x-ray outside the irradiated phantom in order to decrease the scattering effect. Phantom experiments of two tubes filled with Y2O3:Eu3+ indicated that the proposed method could reduce the scattering by a degree of 30% and can reduce the location error from 1.8mm to 1.2mm. Hence, the proposed method was feasible to the general case and actual experiments and it is easy to implement.

  4. Minimal residual cone-beam reconstruction with attenuation correction in SPECT

    La, Valérie; Grangeat, Pierre

    1998-04-01

    This paper presents an iterative method based on the minimal residual algorithm for tomographic attenuation compensated reconstruction from attenuated cone-beam projections given the attenuation distribution. Unlike conjugate-gradient based reconstruction techniques, the proposed minimal residual based algorithm solves directly a quasisymmetric linear system, which is a preconditioned system. Thus it avoids the use of normal equations, which improves the convergence rate. Two main contributions are introduced. First, a regularization method is derived for quasisymmetric problems, based on a Tikhonov-Phillips regularization applied to the factorization of the symmetric part of the system matrix. This regularization is made spatially adaptive to avoid smoothing the region of interest. Second, our existing reconstruction algorithm for attenuation correction in parallel-beam geometry is extended to cone-beam geometry. A circular orbit is considered. Two preconditioning operators are proposed: the first one is Grangeat's inversion formula and the second one is Feldkamp's inversion formula. Experimental results obtained on simulated data are presented and the shadow zone effect on attenuated data is illustrated.

  5. Phantom dosimetry and image quality of i-CAT FLX cone-beam computed tomography

    Ludlow, John B.; Walker, Cameron

    2013-01-01

    Introduction Increasing use of cone-beam computed tomography in orthodontics has been coupled with heightened concern with the long-term risks of x-ray exposure in orthodontic populations. An industry response to this has been to offer low-exposure alternative scanning options in newer cone-beam computed tomography models. Methods Effective doses resulting from various combinations of field size, and field location comparing child and adult anthropomorphic phantoms using the recently introduced i-CAT FLX cone-beam computed tomography unit were measured with Optical Stimulated Dosimetry using previously validated protocols. Scan protocols included High Resolution (360° rotation, 600 image frames, 120 kVp, 5 mA, 7.4 sec), Standard (360°, 300 frames, 120 kVp, 5 mA, 3.7 sec), QuickScan (180°, 160 frames, 120 kVp, 5 mA, 2 sec) and QuickScan+ (180°, 160 frames, 90 kVp, 3 mA, 2 sec). Contrast-to-noise ratio (CNR) was calculated as a quantitative measure of image quality for the various exposure options using the QUART DVT phantom. Results Child phantom doses were on average 36% greater than Adult phantom doses. QuickScan+ protocols resulted in significantly lower doses than Standard protocols for child (p=0.0167) and adult (p=0.0055) phantoms. 13×16 cm cephalometric fields of view ranged from 11–85 μSv in the adult phantom and 18–120 μSv in the child for QuickScan+ and Standard protocols respectively. CNR was reduced by approximately 2/3rds comparing QuickScan+ to Standard exposure parameters. Conclusions QuickScan+ effective doses are comparable to conventional panoramic examinations. Significant dose reductions are accompanied by significant reductions in image quality. However, this trade-off may be acceptable for certain diagnostic tasks such as interim assessment of treatment results. PMID:24286904

  6. Accuracy Assessment of Three-dimensional Surface Reconstructions of In vivo Teeth from Cone-beam Computed Tomography

    Yan-Hui Sang; Hong-Cheng Hu; Song-He Lu; Yu-Wei Wu; Wei-Ran Li; Zhi-Hui Tang

    2016-01-01

    Background:The accuracy of three-dimensional (3D) reconstructions from cone-beam computed tomography (CBCT) has been particularly important in dentistry,which will affect the effectiveness of diagnosis,treatment plan,and outcome in clinical practice.The aims of this study were to assess the linear,volumetric,and geometric accuracy of 3D reconstructions from CBCT and to investigate the influence of voxel size and CBCT system on the reconstructions results.Methods:Fifty teeth from 18 orthodontic patients were assigned to three groups as NewTom VG 0.15 mm group (NewTom VG;voxel size:0.15 mm;n =17),NewTom VG 0.30 mm group (NewTom VG;voxel size:0.30 mm;n =16),and VATECH DCTPRO 0.30 mm group (VATECH DCTPRO;voxel size:0.30 mm;n =17).The 3D reconstruction models of the teeth were segmented from CBCT data manually using Mimics 18.0 (Materialise Dental,Leuven,Belgium),and the extracted teeth were scanned by 3Shape optical scanner (3Shape A/S,Denmark).Linear and volumetric deviations were separately assessed by comparing the length and volume of the 3D reconstruction model with physical measurement by paired t-test.Geometric deviations were assessed by the root mean square value of the imposed 3D reconstruction and optical models by one-sample t-test.To assess the influence of voxel size and CBCT system on 3D reconstruction,analysis of variance (ANOVA) was used (α =0.05).Results:The linear,volumetric,and geometric deviations were-0.03 ± 0.48 mm,-5.4 ± 2.8%,and 0.117 ± 0.018 mm for NewTom VG 0.15 mm group;-0.45 ± 0.42 mm,-4.5 ± 3.4%,and 0.116 ± 0.014 mm for NewTom VG 0.30 mm group;and-0.93 ± 0.40 mm,-4.8 ± 5.1%,and 0.194 ± 0.117 mm for VATECH DCTPRO 0.30 mm group,respectively.There were statistically significant differences between groups in terms of linear measurement (P < 0.001),but no significant difference in terms of volumetric measurement (P =0.774).No statistically significant difference were found on geometric measurement between NewTom VG 0.15 mm and

  7. Cone beam computed tomography aided diagnosis and treatment of endodontic cases: Critical analysis

    Funda Y?lmaz; K?van? Kamburoglu; Naz Yakar Yeta; Meltem Dartar ?ztan

    2016-01-01

    Although intraoral radiographs still remain the imaging method of choice for the evaluation of endodontic patients, in recent years, the utilization of cone beam computed tomography(CBCT) in endodontics showed a significant jump. This case series presentation shows the importance of CBCT aided diagnosis and treatment of complex endodontic cases such as; root resorption, missed extra canal, fusion, oblique root fracture, nondiagnosed periapical pathology and horizontal root fracture. CBCT may be a useful diagnostic method in several endodontic cases where intraoral radiography and clinical examination alone are unable to provide sufficient information.

  8. Conservative Management of Type III Dens in Dente Using Cone Beam Computed Tomography

    K Pradeep

    2012-01-01

    Full Text Available Dens in dente, also known as dens invaginatus, dilated composite odontoma, or deep foramen caecum, is a developmental malformation that usually affects maxillary incisor teeth, particularly lateral incisors. It may occur in teeth anywhere within the jaws, other locations are comparatively rare. It can occur within both the crown and the root, although crown invaginations are more common. The use of cone beam computed tomography (CBCT is very helpful in endodontic diagnosis of complex anatomic variations. In this case we demonstrate the use of CBCT in the evaluation and endodontic management of a Type III dens in dente (Oehler′s Type III.

  9. A multiscale filter for noise reduction of low-dose cone beam projections

    Yao, Weiguang; Farr, Jonathan B.

    2015-08-01

    The Poisson or compound Poisson process governs the randomness of photon fluence in cone beam computed tomography (CBCT) imaging systems. The probability density function depends on the mean (noiseless) of the fluence at a certain detector. This dependence indicates the natural requirement of multiscale filters to smooth noise while preserving structures of the imaged object on the low-dose cone beam projection. In this work, we used a Gaussian filter, \\text{exp}≤ft(-{{x}2}/2σ f2\\right) as the multiscale filter to de-noise the low-dose cone beam projections. We analytically obtained the expression of {σf} , which represents the scale of the filter, by minimizing local noise-to-signal ratio. We analytically derived the variance of residual noise from the Poisson or compound Poisson processes after Gaussian filtering. From the derived analytical form of the variance of residual noise, optimal σ f2 is proved to be proportional to the noiseless fluence and modulated by local structure strength expressed as the linear fitting error of the structure. A strategy was used to obtain the reliable linear fitting error: smoothing the projection along the longitudinal direction to calculate the linear fitting error along the lateral direction and vice versa. The performance of our multiscale filter was examined on low-dose cone beam projections of a Catphan phantom and a head-and-neck patient. After performing the filter on the Catphan phantom projections scanned with pulse time 4 ms, the number of visible line pairs was similar to that scanned with 16 ms, and the contrast-to-noise ratio of the inserts was higher than that scanned with 16 ms about 64% in average. For the simulated head-and-neck patient projections with pulse time 4 ms, the visibility of soft tissue structures in the patient was comparable to that scanned with 20 ms. The image processing took less than 0.5 s per projection with 1024   ×   768 pixels.

  10. [Radiographic evaluation of cone-beam computed tomography for oral implants: maxillary sinus].

    Wang, Hu

    2015-08-01

    Cone-beam computed tomography (CBCT) has an important function in understanding implant operations. CBCT can be used to evaluate the basic condition of implant site before implant operation and decide whether it is suitable for implanting. CBCT also ensures whether the direction of implant and the operation method are satisfactory. CBCT can be used pre- or post-operation as long as the case involves the maxillary sinus. Clinical implant cases using CBCT were introduced to evaluate the maxillary sinus pre- or post-operation.

  11. Cone-beam computed tomography: Time to move from ALARA to ALADA

    Jaju, Prashant P.; Jaju, Sushma P. [Rishiraj College of Dental Sciences and Research Centre, Bhopa(Indonesia)

    2015-12-15

    Cone-beam computed tomography (CBCT) is routinely recommended for dental diagnosis and treatment planning. CBCT exposes patients to less radiation than does conventional CT. Still, lack of proper education among dentists and specialists is resulting in improper referral for CBCT. In addition, aiming to generate high-quality images, operators may increase the radiation dose, which can expose the patient to unnecessary risk. This letter advocates appropriate radiation dosing during CBCT to the benefit of both patients and dentists, and supports moving from the concept of 'as low as reasonably achievable' (ALARA) to 'as low as diagnostically acceptable' (ALADA.

  12. A multiscale filter for noise reduction of low-dose cone beam projections.

    Yao, Weiguang; Farr, Jonathan B

    2015-08-21

    The Poisson or compound Poisson process governs the randomness of photon fluence in cone beam computed tomography (CBCT) imaging systems. The probability density function depends on the mean (noiseless) of the fluence at a certain detector. This dependence indicates the natural requirement of multiscale filters to smooth noise while preserving structures of the imaged object on the low-dose cone beam projection. In this work, we used a Gaussian filter, exp(-x2/2σ(2)(f)) as the multiscale filter to de-noise the low-dose cone beam projections. We analytically obtained the expression of σ(f), which represents the scale of the filter, by minimizing local noise-to-signal ratio. We analytically derived the variance of residual noise from the Poisson or compound Poisson processes after Gaussian filtering. From the derived analytical form of the variance of residual noise, optimal σ(2)(f)) is proved to be proportional to the noiseless fluence and modulated by local structure strength expressed as the linear fitting error of the structure. A strategy was used to obtain the reliable linear fitting error: smoothing the projection along the longitudinal direction to calculate the linear fitting error along the lateral direction and vice versa. The performance of our multiscale filter was examined on low-dose cone beam projections of a Catphan phantom and a head-and-neck patient. After performing the filter on the Catphan phantom projections scanned with pulse time 4 ms, the number of visible line pairs was similar to that scanned with 16 ms, and the contrast-to-noise ratio of the inserts was higher than that scanned with 16 ms about 64% in average. For the simulated head-and-neck patient projections with pulse time 4 ms, the visibility of soft tissue structures in the patient was comparable to that scanned with 20 ms. The image processing took less than 0.5 s per projection with 1024   ×   768 pixels.

  13. Florid cemento-osseous dysplasia: A rare case report evaluated with cone-beam computed tomography

    Eren Yildirim

    2016-01-01

    Full Text Available A 29-year-old systemically healthy female patient presented to our department. Cone-beam computed tomographic images showed multiple well-defined sclerotic masses with radiolucent border in both right and left molar regions of the mandible. These sclerotic masses were surrounded by a thin radiolucent border. We diagnosed the present pathology as florid cemento-osseous dysplasia and decided to follow the patient without taking biopsy. For the patient, who did not have any clinical complaints, radiographic followupis recommended twice a year. The responsibility of the dentist is to ensure the follow-up of the diagnosed patients and take necessary measures for preventing the infections.

  14. Role of cone beam computed tomography in the prompt diagnosis of a nasopalatine duct cyst

    Sapna Panjwani

    2014-01-01

    Full Text Available The nasopalatine duct cyst (NPDC is the most common of all the developmental, epithelial, and non-odontogenic cysts of the maxilla, believed to originate from the epithelial remnants of the nasopalatine duct. Typically, the lesion is asymptomatic and is detected accidentally on a radiograph. The definite diagnosis must be based on the clinical, radiological, and histopathological findings. Frequently misdiagnosed, the NPDC is not rare. The motive of reporting an entity that is not very rare is that the lesion is mostly misdiagnosed, and to emphasize the importance of cone-beam computed tomography (CBCT in the diagnosis and optimized treatment planning of NPDCs.

  15. A service for monitoring the quality of intraoperative cone beam CT images

    Heckel Frank

    2016-09-01

    Full Text Available In recent years, operating rooms (ORs have transformed into integrated operating rooms, where devices are able to communicate, exchange data, or even steer and control each other. However, image data processing is commonly done by dedicated workstations for specific clinical use-cases. In this paper, we propose a concept for a dynamic service component for image data processing on the example of automatic image quality assessment (AQUA of intraoperative cone beam computed tomography (CBCT images. The service is build using the Open Surgical Communication Protocol (OSCP and the standard for Digital Imaging and Communications in Medicine (DICOM. We have validated the proposed concept in an integrated demonstrator OR.

  16. The effect of voxel size on the measurement of mandibular thickness in cone-beam computed tomography

    Ehsan Hekmatian

    2014-01-01

    Full Text Available Background: Cone-beam computed tomography (CBCT is a new imaging technology that has been widely used in implantology, oral and maxillofacial surgery and orthodontics. This method provides 3-D images that are composed of voxel, which is the smallest image unit, and determines image resolution. Smaller voxel is associated with the higher resolution and also greater radiation exposure. This study was aimed to find out the effect of voxel size on the measurement of mandibular thickness. Materials and Methods: Using voxel sizes of 0.30 mm and 0.15 mm, two CBCT protocols (protocol 1: Field of view (FOV of 15 cm, 85 kVp, 42 mAs, 0.15 mm voxel, 14 s scan time; protocol 2: FOV of 15 cm, 85 kVp, 10 mAs, 0.30 mm voxel, 14 s scan time were carried out on 16 dry human mandibles with permanent dentition. Mandibular thickness was measured at seven different sites (midline region, bilateral canine regions, bilateral mental foramen regions and bilateral molar regions. Analysis of variance was used for analysis of data using the Statistical Package for the Social Sciences version 20 (SPSS Inc., Chicago, IL, USA. P 0.05. Conclusion: Considering the insignificant differences of the mandibular thickness measurements using different voxel sizes, it would be more reasonable to use 0.30 mm voxel size instead of 0.15 mm voxel size to avoid unnecessary radiation exposure.

  17. Radiologic study of the healing process of the extracted socket of beagle dogs using cone beam CT

    Cho, Bong Won; Lee, Won; Lee, Byung Do [Department of Oral and Maxillofacial Radiology, School of Dentistry, Wonkwang University, Iksan (Korea, Republic of); Kim, De Sok [Department of Electrical Engineering, Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

    2009-03-15

    To longitudinally observe the healing process of extracted socket and the alterations of the residual ridge in healthy adult dogs using cone beam CT (CBCT). The mandibular premolars of two beagle dogs were removed and the extraction sites were covered with the gingival tissue. CBCTs (3D X-ray CT scanner, Alphard vega, Asahi Co.) were taken at baseline and at 1 week interval for 12 weeks. Radiographic density of extracted wounds was measured on normalized images with a custom-made image analysis program. The amount of alveolar crestal resorption after the teeth extraction was measured with a reformatted three-dimensional image using CBCT. Bony healing pattern of extracted wound of each group was also longitudinally observed and analyzed. Dimensional changes occurred during the first 6 weeks following the extraction of dogs' mandibular premolars. The reduction of the height of residual ridge was more pronounced at the buccal than at the lingual aspect of the extraction socket. Radiographic density of extracted wounds increased by week 4, but the change in density stabilized after week 6. New bone formation was observed at the floor and the peripheral side of extracted socket from week 1. The entrance of extracted socket was sealed by a hard-tissue bridge at week 5. The healing process of extracted wound involved a series of events including new bone formation and residual ridge resorption.

  18. Comparison of Cone-Beam Computed Tomography and Periapical Radiography in Predicting Treatment Decision for Periapical Lesions: A Clinical Study

    Ashok Balasundaram

    2012-01-01

    Full Text Available Objectives. To compare the ability of endodontists to determine the size of apical pathological lesions and select the most appropriate choice of treatment based on lesions’ projected image characteristics using 2 D and 3 D images. Study Design. Twenty-four subjects were selected. Radiographic examination of symptomatic study teeth with an intraoral periapical radiograph revealed periapical lesions equal to or greater than 3 mm in the greatest diameter. Cone-beam Computed tomography (CBCT images were made of the involved teeth after the intraoral periapical radiograph confirmed the size of lesion to be equal to greater than 3 mm. Six observers (endodontists viewed both the periapical and CBCT images. Upon viewing each of the images from the two imaging modalities, observers (1 measured lesion size and (2 made decisions on treatment based on each radiograph. Chi-square test was used to look for differences in the choice of treatment among observers. Results. No significant difference was noted in the treatment plan selected by observers using the two modalities (χ2(3=.036, P>0.05. Conclusion. Lesion size and choice of treatment of periapical lesions based on CBCT radiographs do not change significantly from those made on the basis of 2 D radiographs.

  19. Accuracy and speed of robotic assisted needle interventions using a modern cone beam computed tomography intervention suite: a phantom study

    Schulz, Boris [Goethe University Hospital, Institute for Diagnostic and Interventional Radiology, Frankfurt (Germany); Goethe University Hospital, Department of Diagnostic and Interventional Radiology, Frankfurt (Germany); Eichler, Katrin; Siebenhandl, Petra; Gruber-Rouh, Tatjana; Vogl, Thomas Josef; Zangos, Stephan [Goethe University Hospital, Institute for Diagnostic and Interventional Radiology, Frankfurt (Germany); Czerny, Christoph [Goethe University Hospital, Department of Trauma Surgery, Frankfurt (Germany)

    2013-01-15

    To analyse the feasibility and accuracy of robotic aided interventions on a phantom when using a modern C-arm-mounted cone beam computed tomography (CBCT) device in combination with needle guidance software. A small robotic device capable of holding and guiding needles was attached to the intervention table. After acquiring a 3D data set the access path was planned on the CBCT workstation and shown on the intervention monitor. Then the robot was aligned to the live fluoroscopic image. A total of 40 punctures were randomly conducted on a phantom armed with several targets (diameter 2 mm) in single and double oblique trajectory (n = 20 each). Target distance, needle deviation and time for the procedures were analysed. All phantom interventions (n = 40) could be performed successfully. Mean target access path within the phantom was 8.5 cm (min 4.2 cm, max 13.5 cm). Average needle tip deviation was 1.1 mm (min 0 mm, max 4.5 mm), time duration was 3:59 min (min 2:07 min, max 10:37 min). When using the proposed robot device in a CBCT intervention suite, highly accurate needle-based interventional punctures are possible in a reasonable timely manner in single as well as in double oblique trajectories. (orig.)

  20. Utility of the computed tomography indices on cone beam computed tomography images in the diagnosis of osteoporosis in women

    Koh, Kwang Joon; Kim, Kyung A [School of Dentistry, Chonbuk National University, Jeonju (Korea, Republic of)

    2011-09-15

    This study evaluated the potential use of the computed tomography indices (CTI) on cone beam CT (CBCT) images for an assessment of the bone mineral density (BMD) in postmenopausal osteoporotic women. Twenty-one postmenopausal osteoporotic women and 21 postmenopausal healthy women were enrolled as the subjects. The BMD of the lumbar vertebrae and femur were calculated by dual energy X-ray absorptiometry (DXA) using a DXA scanner. The CBCT images were obtained from the unilateral mental foramen region using a PSR-9000N Dental CT system. The axial, sagittal, and coronal images were reconstructed from the block images using OnDemend3D. The new term 'CTI' on CBCT images was proposed. The relationship between the CT measurements and BMDs were assessed and the intra-observer agreement was determined. There were significant differences between the normal and osteoporotic groups in the computed tomography mandibular index superior (CTI(S)), computed tomography mandibular index inferior (CTI(I)), and computed tomography cortical index (CTCI). On the other hand, there was no difference between the groups in the computed tomography mental index (CTMI: inferior cortical width). CTI(S), CTI(I), and CTCI on the CBCT images can be used to assess the osteoporotic women.

  1. A quality assurance framework for the fully automated and objective evaluation of image quality in cone-beam computed tomography

    Steiding, Christian; Kolditz, Daniel; Kalender, Willi A., E-mail: willi.kalender@imp.uni-erlangen.de [Institute of Medical Physics, University of Erlangen-Nürnberg, Henkestraße 91, 91052 Erlangen, Germany and CT Imaging GmbH, 91052 Erlangen (Germany)

    2014-03-15

    Purpose: Thousands of cone-beam computed tomography (CBCT) scanners for vascular, maxillofacial, neurological, and body imaging are in clinical use today, but there is no consensus on uniform acceptance and constancy testing for image quality (IQ) and dose yet. The authors developed a quality assurance (QA) framework for fully automated and time-efficient performance evaluation of these systems. In addition, the dependence of objective Fourier-based IQ metrics on direction and position in 3D volumes was investigated for CBCT. Methods: The authors designed a dedicated QA phantom 10 cm in length consisting of five compartments, each with a diameter of 10 cm, and an optional extension ring 16 cm in diameter. A homogeneous section of water-equivalent material allows measuring CT value accuracy, image noise and uniformity, and multidimensional global and local noise power spectra (NPS). For the quantitative determination of 3D high-contrast spatial resolution, the modulation transfer function (MTF) of centrally and peripherally positioned aluminum spheres was computed from edge profiles. Additional in-plane and axial resolution patterns were used to assess resolution qualitatively. The characterization of low-contrast detectability as well as CT value linearity and artifact behavior was tested by utilizing sections with soft-tissue-equivalent and metallic inserts. For an automated QA procedure, a phantom detection algorithm was implemented. All tests used in the dedicated QA program were initially verified in simulation studies and experimentally confirmed on a clinical dental CBCT system. Results: The automated IQ evaluation of volume data sets of the dental CBCT system was achieved with the proposed phantom requiring only one scan for the determination of all desired parameters. Typically, less than 5 min were needed for phantom set-up, scanning, and data analysis. Quantitative evaluation of system performance over time by comparison to previous examinations was also

  2. SU-E-T-61: A Practical Process for Fabricating Passive Scatter Proton Beam Modulation Compensation Filters Using 3D Printing

    Zhao, T; Drzymala, R [Washington University School of Medicine, St. Louis, MO (United States)

    2015-06-15

    Purpose: The purpose of this project was to devise a practical fabrication process for passive scatter proton beam compensation filters (CF) that is competitive in time, cost and effort using 3D printing. Methods: DICOM compensator filter files for a proton beam were generated by our Eclipse (Varian, Inc.) treatment planning system. The compensator thickness specifications were extracted with in-house software written in Matlab (MathWorks, Inc.) code and written to a text file which could be read by the Rhinoceros 5, computer-aided design (CAD) package (Robert McNeel and Associates), which subsequently generated a smoothed model in a STereoLithographic also known as a Standard Tesselation Language file (STL). The model in the STL file was subsequently refined using Netfabb software and then converted to printing instructions using Cura. version 15.02.1. for our 3D printer. The Airwolf3D, model HD2x, fused filament fabrication (FFF) 3D printer (Airwolf3D.com) was used for our fabrication system with a print speed of 150mm per second. It can print in over 22 different plastic filament materials in a build volume of 11” x 8” x 12”. We choose ABS plastic to print the 3D model of the imprint for our CFs. Results: Prints of the CF could be performed at a print speed of 70mm per second. The time to print the 3D topology for the CF for the 14 cm diameter snout of our Mevion 250 proton accelerator was less than 3 hours. The printed model is intended to subsequently be used as a mold to imprint a molten wax cylindrical to form the compensation after cooling. The whole process should be performed for a typical 3 beam treatment plan within a day. Conclusion: Use of 3D printing is practical and can be used to print a 3D model of a CF within a few hours.

  3. Cone beam breast CT with multiplanar and three dimensional visualization in differentiating breast masses compared with mammography

    Zhao, Binghui [Department of Radiology, Shanghai Tenth People' s Hospital, Tongji University, Shanghai 200072 (China); Zhang, Xiaohua [Department of Electrical and Computer Engineering, University of Rochester, Rochester, NY 14627 (United States); Cai, Weixing [Department of Imaging Sciences, University of Rochester Medical Center, Rochester, NY 14642 (United States); Conover, David [Koning Corporation, West Henrietta, NY 14586 (United States); Ning, Ruola, E-mail: ruola_ning@urmc.rochester.edu [Department of Imaging Sciences, University of Rochester Medical Center, Rochester, NY 14642 (United States)

    2015-01-15

    Objective: This pilot study was to evaluate cone beam breast computed tomography (CBBCT) with multiplanar and three dimensional (3D) visualization in differentiating breast masses in comparison with two-view mammograms. Methods: Sixty-five consecutive female patients (67 breasts) were scanned by CBBCT after conventional two-view mammography (Hologic, Motarget, compression factor 0.8). For CBBCT imaging, three hundred (1024 × 768 × 16 b) two-dimensional (2D) projection images were acquired by rotating the x-ray tube and a flat panel detector (FPD) 360 degree around one breast. Three-dimensional CBBCT images were reconstructed from the 2D projections. Visage CS 3.0 and Amira 5.2.2 were used to visualize reconstructed CBBCT images. Results: Eighty-five breast masses in this study were evaluated and categorized under the breast imaging reporting and data system (BI-RADS) according to plain CBBCT images and two-view mammograms, respectively, prior to biopsy. BI-RADS category of each breast was compared with biopsy histopathology. The results showed that CBBCT with multiplanar and 3D visualization would be helpful to identify the margin and characteristics of breast masses. The category variance ratios for CBBCT under the BI-RADS were 23.5% for malignant tumors (MTs) and 27.3% for benign lesions in comparison with pathology, which were evidently closer to the histopathology results than those of two-view mammograms, p value <0.01. With the receiver operating characteristic (ROC) curve analysis, the area under the curve (AUC) of CBBCT was 0.911, larger than that (AUC 0.827) of two-view mammograms, p value <0.01. Conclusion: CBBCT will be a distinctive noninvasive technology in differentiating and categorizing breast masses under BI-RADS. CBBCT may be considerably more effective to identify breast masses, especially some small, uncertain or multifocal masses than conventional two-view mammography.

  4. Evaluation of subjective image quality in relation to diagnostic task for cone beam computed tomography with different fields of view

    Lofthag-Hansen, Sara, E-mail: sara.lofthag-hansen@vgregion.se [Department of Oral and Maxillofacial Radiology, Sahlgrenska Academy at the University of Gothenburg, Gothenburg (Sweden); Clinic of Oral and Maxillofacial Radiology, Public Dental Health, Gothenburg (Sweden); Thilander-Klang, Anne, E-mail: anne.thilander-klang@vgregion.se [Department of Radiation Physics, Institute of Clinical Sciences, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg (Sweden); Department of Medical Physics and Biomedical Engineering, Sahlgrenska University Hospital, Gothenburg (Sweden); Groendahl, Kerstin, E-mail: kerstin.grondahl@lj.se [Department of Oral and Maxillofacial Radiology, Sahlgrenska Academy at the University of Gothenburg, Gothenburg (Sweden); Department of Oral and Maxillofacial Radiology, The Institute for Postgraduate Dental Education, Joenkoeping (Sweden)

    2011-11-15

    Aims: To evaluate subjective image quality for two diagnostic tasks, periapical diagnosis and implant planning, for cone beam computed tomography (CBCT) using different exposure parameters and fields of view (FOVs). Materials and methods: Examinations were performed in posterior part of the jaws on a skull phantom with 3D Accuitomo (FOV 3 cm x 4 cm) and 3D Accuitomo FPD (FOVs 4 cm x 4 cm and 6 cm x 6 cm). All combinations of 60, 65, 70, 75, 80 kV and 2, 4, 6, 8, 10 mA with a rotation of 180{sup o} and 360{sup o} were used. Dose-area product (DAP) value was determined for each combination. The images were presented, displaying the object in axial, cross-sectional and sagittal views, without scanning data in a random order for each FOV and jaw. Seven observers assessed image quality on a six-point rating scale. Results: Intra-observer agreement was good ({kappa}{sub w} = 0.76) and inter-observer agreement moderate ({kappa}{sub w} = 0.52). Stepwise logistic regression showed kV, mA and diagnostic task to be the most important variables. Periapical diagnosis, regardless jaw, required higher exposure parameters compared to implant planning. Implant planning in the lower jaw required higher exposure parameters compared to upper jaw. Overall ranking of FOVs gave 4 cm x 4 cm, 6 cm x 6 cm followed by 3 cm x 4 cm. Conclusions: This study has shown that exposure parameters should be adjusted according to diagnostic task. For this particular CBCT brand a rotation of 180{sup o} gave good subjective image quality, hence a substantial dose reduction can be achieved without loss of diagnostic information.

  5. A comparative study of high resolution cone beam X-ray tomography and synchrotron tomography applied to Fe- and Al-alloys.

    Kastner, Johann; Harrer, Bernhard; Requena, Guillermo; Brunke, Oliver

    2010-10-01

    X-ray computed tomography (XCT) has become a very important method for non-destructive 3D-characterization and evaluation of materials. Due to measurement speed and quality, XCT systems with cone beam geometry and matrix detectors have gained general acceptance. Continuous improvements in the quality and performance of X-ray tubes and XCT devices have led to cone beam CT systems that can now achieve spatial resolutions down to 1 μm and even below. However, the polychromatic nature of the source, limited photon flux and cone beam artefacts mean that there are limits to the quality of the CT-data achievable; these limits are particularly pronounced with materials of higher density like metals. Synchrotron radiation offers significant advantages by its monochromatic and parallel beam of high brilliance. These advantages usually cause fewer artefacts, improved contrast and resolution.Tomography data of a steel sample and of two multi-phase Al-samples (AlSi12Ni1, AlMg5Si7) are recorded by advanced cone beam XCT-systems with a μ-focus (μXCT) and a sub-μm (nano-focus, sub-μXCT) X-ray source with voxel dimensions between 0.4 and 3.5 μm and are compared with synchrotron computed tomography (sXCT) with 0.3 μm/voxel. CT data features like beam hardening and ring artefacts, detection of details, sharpness, contrast, signal-to-noise ratio and the grey value histogram are systematically compared. In all cases μXCT displayed the lowest performance. Sub-μXCT gives excellent results in the detection of details, spatial and contrast resolution, which are comparable to synchrotron-XCT recordings. The signal-to-noise ratio is usually significantly lower for sub-μXCT compared with the two other methods. With regard to measurement costs "for industrial users", scanning volume, accessibility and user-friendliness sub-μXCT has significant advantages in comparison to synchrotron-XCT.

  6. Assessment of protocols in cone beam CT with symmetric and asymmetric beam using effective dose and P{sub ka}

    Batista, W. O.; Linhares de O, M. V. [Instituto Federal da Bahia, Rua Emidio dos Santos s/n, Barbalho, Salvador, 40301015 Bahia (Brazil); Soares, M. R.; Maia, A. F. [Universidade Federal de Sergipe, Departamento de Fisica, Cidade Universitaria Prof. Jose Aloisio de Campos, Marechal Rondon s/n, Jardim Rosa Elze, 49-100000 Sao Cristovao, Sergipe (Brazil); Caldas, L. V. E., E-mail: wilsonottobatista@gmail.com [Instituto de Pesquisas Energeticas e Nucleares / CNEN, Av. Lineu Prestes 2242, Cidade Universitaria, 05508-000 Sao Paulo (Brazil)

    2014-08-15

    The cone beam CT is an emerging technology in dental radiology with significant differences the point of view of design technology between the various manufacturers on the world market. This study aims to evaluate and compare protocols with similar purposes in a cone beam CT scanner using TLDs and air kerma - area product (P{sub ka}) as kerma index. Measurements were performed on two protocols used to obtain the image the maxilla-mandible in equipment Gendex GXCB 500: Protocol [GX1] extended diameter and asymmetric beam (14 cm x 8.5 cm - maxilla / mandible) and protocol [GX2] symmetrical beam (8.5 cm x 8.5 cm - maxillary / mandible). Was used LiF dosimeters (TLD 100) inserted into a female anthropomorphic phantom manufactured by Radiology Support Devices. For all protocols evaluated the value of P{sub ka} using a meter Diamentor E2 and PTW system Radcal Rapidose. The results obtained for Effective Dose / P{sub ka} these measurements were separated by protocol image. Protocol [GX1]: 44.5 μSv/478 mGy cm{sup 2}; protocol [GX2]: 54.8 μSv/507 mGy cm{sup 2}. These values indicate that the relationship between the diameter of the image acquired in the protocol [GX1] and the diameter of the image in the protocol [GX2] is equal to 1.65, the Effective Dose for the first protocol has lower value at 18%. P{sub ka} values reveal very similar results between the two protocols, although, common sense leads to the interpretation that imaging protocols with field of view (Fov) of large diameters imply high values of effective dose when compared to small diameters. However, in this particular case, this is not true due to the asymmetrical beam technology. Conclude that for the cases where the scanner uses asymmetric beam to obtain images with large diameters that cover the entire face there are advantages from the point of view of reducing the exposure of patients with respect to the use of symmetrical beam and / or to Fov images with a smaller diameter. (Author)

  7. Simulation of Cone Beam CT System Based on Monte Carlo Method

    Wang, Yu; Cao, Ruifen; Hu, Liqin; Li, Bingbing

    2014-01-01

    Adaptive Radiation Therapy (ART) was developed based on Image-guided Radiation Therapy (IGRT) and it is the trend of photon radiation therapy. To get a better use of Cone Beam CT (CBCT) images for ART, the CBCT system model was established based on Monte Carlo program and validated against the measurement. The BEAMnrc program was adopted to the KV x-ray tube. Both IOURCE-13 and ISOURCE-24 were chosen to simulate the path of beam particles. The measured Percentage Depth Dose (PDD) and lateral dose profiles under 1cm water were compared with the dose calculated by DOSXYZnrc program. The calculated PDD was better than 1% within the depth of 10cm. More than 85% points of calculated lateral dose profiles was within 2%. The correct CBCT system model helps to improve CBCT image quality for dose verification in ART and assess the CBCT image concomitant dose risk.

  8. WE-FG-207A-03: Low-Dose Cone-Beam Breast CT: Physics and Technology Development.

    Boone, J

    2016-06-01

    dedicated breast CT. The development of large-area flat-panel detectors with field-of-view sufficient to image the entire breast in each projection enabled development of flat-panel cone-beam breast CT. More recently, the availability of complimentary metal-oxide semiconductor (CMOS) detectors with lower system noise and finer pixel pitch, combined with the development of x-ray tubes with focal spot dimensions similar to mammography systems, has shown improved spatial resolution and could improve visualization of microcalcifications. These technological developments promise clinical translation of low-dose cone-beam breast CT. Dedicated photon-counting breast CT (pcBCT) systems represent a novel detector design, which provide high spatial resolution (∼ 100µm) and low mean glandular dose (MGD). The CdTe-based direct conversion detector technology was previously evaluated and confirmed by simulations and basic experiments on laboratory setups [Kalender et al., Eur Radiol 22: 1-8, 2012]. Measurements of dose, technical image quality parameters, and surgical specimens on a pcBCT scanner have been completed. Comparative evaluation of surgical specimens showed that pcBCT outperformed mammography and digital breast tomosynthesis with respect to 3D spatial resolution, detectability of calcifications, and soft tissue delineation. Major barriers to widespread clinical use of BCT relate to radiation dose, imaging of microcalcifications, and adequate coverage of breast tissue near the chest wall. Adequate chest wall coverage is also technically challenging but recent progress in x-ray tube, detector and table design now enables full breast coverage in the majority of patients. At this time, BCT has been deemed to be suitable for diagnostic imaging but not yet for screening. The mean glandular dose (MGD) from BCT has been reported to be between 5.7 to 27.8 mGy, and this range is comparable to, and within the range of, the MGD of 2.6 to 31.6 mGy in diagnostic mammography. In

  9. Patient dose and image quality from mega-voltage cone beam computed tomography imaging.

    Gayou, Olivier; Parda, David S; Johnson, Mark; Miften, Moyed

    2007-02-01

    The evolution of ever more conformal radiation delivery techniques makes the subject of accurate localization of increasing importance in radiotherapy. Several systems can be utilized including kilo-voltage and mega-voltage cone-beam computed tomography (MV-CBCT), CT on rail or helical tomography. One of the attractive aspects of mega-voltage cone-beam CT is that it uses the therapy beam along with an electronic portal imaging device to image the patient prior to the delivery of treatment. However, the use of a photon beam energy in the mega-voltage range for volumetric imaging degrades the image quality and increases the patient radiation dose. To optimize image quality and patient dose in MV-CBCT imaging procedures, a series of dose measurements in cylindrical and anthropomorphic phantoms using an ionization chamber, radiographic films, and thermoluminescent dosimeters was performed. Furthermore, the dependence of the contrast to noise ratio and spatial resolution of the image upon the dose delivered for a 20-cm-diam cylindrical phantom was evaluated. Depending on the anatomical site and patient thickness, we found that the minimum dose deposited in the irradiated volume was 5-9 cGy and the maximum dose was between 9 and 17 cGy for our clinical MV-CBCT imaging protocols. Results also demonstrated that for high contrast areas such as bony anatomy, low doses are sufficient for image registration and visualization of the three-dimensional boundaries between soft tissue and bony structures. However, as the difference in tissue density decreased, the dose required to identify soft tissue boundaries increased. Finally, the dose delivered by MV-CBCT was simulated using a treatment planning system (TPS), thereby allowing the incorporation of MV-CBCT dose in the treatment planning process. The TPS-calculated doses agreed well with measurements for a wide range of imaging protocols.

  10. A novel image-domain-based cone-beam computed tomography enhancement algorithm

    Li Xiang; Li Tianfang; Yang Yong; Heron, Dwight E; Huq, M Saiful, E-mail: lix@upmc.edu [Department of Radiation Oncology, University of Pittsburgh Cancer Institute, Pittsburgh, PA 15232 (United States)

    2011-05-07

    Kilo-voltage (kV) cone-beam computed tomography (CBCT) plays an important role in image-guided radiotherapy. However, due to a large cone-beam angle, scatter effects significantly degrade the CBCT image quality and limit its clinical application. The goal of this study is to develop an image enhancement algorithm to reduce the low-frequency CBCT image artifacts, which are also called the bias field. The proposed algorithm is based on the hypothesis that image intensities of different types of materials in CBCT images are approximately globally uniform (in other words, a piecewise property). A maximum a posteriori probability framework was developed to estimate the bias field contribution from a given CBCT image. The performance of the proposed CBCT image enhancement method was tested using phantoms and clinical CBCT images. Compared to the original CBCT images, the corrected images using the proposed method achieved a more uniform intensity distribution within each tissue type and significantly reduced cupping and shading artifacts. In a head and a pelvic case, the proposed method reduced the Hounsfield unit (HU) errors within the region of interest from 300 HU to less than 60 HU. In a chest case, the HU errors were reduced from 460 HU to less than 110 HU. The proposed CBCT image enhancement algorithm demonstrated a promising result by the reduction of the scatter-induced low-frequency image artifacts commonly encountered in kV CBCT imaging.

  11. Investigation of saddle trajectories for cardiac CT imaging in cone-beam geometry

    Pack, Jed D [Department of Radiology, University of Utah, Salt Lake City, UT 84112 (United States); Noo, Frederic [Department of Radiology, University of Utah, Salt Lake City, UT 84112 (United States); Kudo, H [Department of Computer Science, Graduate School of Systems and Information Engineering, University of Tsukuba (Japan)

    2004-06-07

    This paper investigates cone-beam tomography for a wide class of x-ray source trajectories called saddles. In particular, a mathematical analysis of the number of intersections between a saddle and an arbitrary plane is given. This analysis demonstrates that axially truncated cone-beam projections acquired along a saddle can be used for exact reconstruction at any point in a large volume. The reconstruction can be achieved either using a new algorithm presented herein or using a formula recently introduced by Katsevich (2003 Int. J. Math. Math. Sci. 21 1305-21). The shape of the reconstructed volume and the properties of saddles make saddles attractive for cardiac imaging. Three examples of saddles are presented with a discussion of implementation on devices similar to modern C-arm systems and multislice CT scanners. Reconstruction with one of these saddles has been tested using computer-simulated data, with and without truncation. The imaged phantom for the truncated data is a FORBILD head phantom (representing the heart) that has been modified and embedded inside the FORBILD thorax phantom. The non-truncated data were generated by excluding the thorax. The reconstructed images demonstrate the accuracy of the mathematical results.

  12. Augmented reality and cone beam CT guidance for transoral robotic surgery.

    Liu, Wen P; Richmon, Jeremy D; Sorger, Jonathan M; Azizian, Mahdi; Taylor, Russell H

    2015-09-01

    In transoral robotic surgery preoperative image data do not reflect large deformations of the operative workspace from perioperative setup. To address this challenge, in this study we explore image guidance with cone beam computed tomographic angiography to guide the dissection of critical vascular landmarks and resection of base-of-tongue neoplasms with adequate margins for transoral robotic surgery. We identify critical vascular landmarks from perioperative c-arm imaging to augment the stereoscopic view of a da Vinci si robot in addition to incorporating visual feedback from relative tool positions. Experiments resecting base-of-tongue mock tumors were conducted on a series of ex vivo and in vivo animal models comparing the proposed workflow for video augmentation to standard non-augmented practice and alternative, fluoroscopy-based image guidance. Accurate identification of registered augmented critical anatomy during controlled arterial dissection and en bloc mock tumor resection was possible with the augmented reality system. The proposed image-guided robotic system also achieved improved resection ratios of mock tumor margins (1.00) when compared to control scenarios (0.0) and alternative methods of image guidance (0.58). The experimental results show the feasibility of the proposed workflow and advantages of cone beam computed tomography image guidance through video augmentation of the primary stereo endoscopy as compared to control and alternative navigation methods.

  13. Assessment of simulated mandibular condyle bone lesions by cone beam computed tomography

    Marques, Alexandre Perez; Perrella, Andreia; Arita, Emiko Saito; Pereira, Marlene Fenyo Soeiro de Matos; Cavalcanti, Marcelo de Gusmao Paraiso, E-mail: alexperez34@gmail.co [Universidade de Sao Paulo (USP), SP (Brazil). Faculdade de Odontologia. Dept. de Estomatologia

    2010-10-15

    There are many limitations to image acquisition, using conventional radiography, of the temporomandibular joint (TMJ) region. The Computed Tomography (CT) scan is a better option, due to its higher accuracy, for purposes of diagnosis, surgical planning and treatment of bone injuries. The aim of the present study was to analyze two protocols of cone beam computed tomography for the evaluation of simulated mandibular condyle bone lesions. Spherical lesions were simulated in 30 dry mandibular condyles, using dentist drills and drill bits sizes 1, 3 and 6. Each of the mandibular condyles was submitted to cone beam computed tomography (CBCT) using two protocols: axial, coronal and sagittal multiplanar reconstruction (MPR); and sagittal plus coronal slices throughout the longitudinal axis of the mandibular condyles. For these protocols, 2 observers analyzed the CBCT images independently, regarding the presence or not of injuries. Only one of the observers, however, performed on 2 different occasions. The results were compared to the gold standard, evaluating the percentage of agreement, degree of accuracy of CBCT protocols and observers' examination. The z test was used for the statistical analysis. The results showed there were no statistically significant differences between the 2 protocols. There was greater difficulty in the assessment of small-size simulated lesions (drill no.1). From the results of this study, it can be concluded that CBCT is an accurate tool for analyzing mandibular condyle bone lesions, with the MPR protocol showing slightly better results than the sagittal plus coronal slices throughout the longitudinal axis. (author)

  14. Differences between panoramic and Cone Beam-CT in the surgical evaluation of lower third molars

    Rodriguez y Baena, Ruggero; Beltrami, Riccardo; Tagliabo, Angelo; Rizzo, Silvana

    2017-01-01

    Background The aim of this study was to evaluate the ability to identify the contiguity between the root of the mandibular third molar and the mandibular canal (MC) in panoramic radiographs compared with Cone Beam-CT. Material and Methods Panoramic radiographs of 326 third molars and CBCT radiographs of 86 cases indicated for surgery and considered at risk were evaluated. The following signs were assessed in panoramic radiographs as risk factors: radiolucent band, loss of MC border, change in MC direction, MC narrowing, root narrowing, root deviation, bifid apex, superimposition, and contact between the root third molar and the MC. Results Radiographic signs associated with absence of MC cortical bone are: radiolucent band, loss of MC border, change in MC direction, and superimposition. The number of risk factors was significantly increased with an increasing depth of inclusion. CBCT revealed a significant association between the absence of MC cortical bone and a lingual or interradicular position of the MC. Conclusions In cases in which panoramic radiographs do not exclude contiguity between the MC and tooth, careful assessment the signs and risks on CBCT radiographs is indicated for proper identification of the relationships between anatomic structures. Key words:Panoramic radiography, Cone-Beam computed tomography, third molar, mandibular nerve. PMID:28210446

  15. Initial Experience with a Cone-beam Breast Computed Tomography-guided Biopsy System

    Seifert, Posy J; Morgan, Renee C; Conover, David L; Arieno, Andrea L

    2017-01-01

    Objective: To evaluate our initial experience with a cone-beam breast computed tomography (BCT)-guided breast biopsy system for lesion retrieval in phantom studies for use with a cone-beam BCT imaging system. Materials and Methods: Under the Institutional Review Board approval, a phantom biopsy study was performed using a dedicated BCT-guided biopsy system. Fifteen biopsies were performed on each of the small, medium, and large anthropomorphic breast phantoms with both BCT and stereotactic guidance for comparison. Each set of the 45 phantoms contained masses and calcification clusters of varying sizes. Data included mass/calcium retrieval rate and dose and length of procedure time for phantom studies. Results: Phantom mass and calcium retrieval rate were 100% for BCT and stereotactic biopsy. BCT dose for small and medium breast phantoms was found to be equivalent to or less than the corresponding stereotactic approach. Stereotactic-guided biopsy dose was 34.2 and 62.5 mGy for small and medium breast phantoms, respectively. BCT-guided biopsy dose was 15.4 and 30.0 mGy for small and medium breast phantoms, respectively. Both computed tomography biopsy and stereotactic biopsy study time ranged from 10 to 20 min. Conclusion: Initial experience with a BCT-guided biopsy system has shown to be comparable to stereotactic biopsy in phantom studies with equivalent or decreased dose. PMID:28217404

  16. A denoising algorithm for projection measurements in cone-beam computed tomography.

    Karimi, Davood; Ward, Rabab

    2016-02-01

    The ability to reduce the radiation dose in computed tomography (CT) is limited by the excessive quantum noise present in the projection measurements. Sinogram denoising is, therefore, an essential step towards reconstructing high-quality images, especially in low-dose CT. Effective denoising requires accurate modeling of the photon statistics and of the prior knowledge about the characteristics of the projection measurements. This paper proposes an algorithm for denoising low-dose sinograms in cone-beam CT. The proposed algorithm is based on minimizing a cost function that includes a measurement consistency term and two regularizations in terms of the gradient and the Hessian of the sinogram. This choice of the regularization is motivated by the nature of CT projections. We use a split Bregman algorithm to minimize the proposed cost function. We apply the algorithm on simulated and real cone-beam projections and compare the results with another algorithm based on bilateral filtering. Our experiments with simulated and real data demonstrate the effectiveness of the proposed algorithm. Denoising of the projections with the proposed algorithm leads to a significant reduction of the noise in the reconstructed images without oversmoothing the edges or introducing artifacts.

  17. Direct aneurysm sac catheterization and embolization of an enlarging internal iliac aneurysm using cone-beam CT

    Merchant, Monish; Shah, Rohan; Resnick, Scott

    2015-01-01

    Since cone-beam computed tomography (CT) has been adapted for use with a C-arm system it has brought volumetric CT capabilities in the interventional suite. Although cone-beam CT image resolution is far inferior to that generated by traditional CT scanners, the system offers the ability to place an access needle into position under tomographic guidance and use the access to immediately begin a fluoroscopic procedure without moving the patient. We describe a case of a “jailed” enlarging internal iliac artery aneurysm secondary to abdominal aortic aneurysm repair, in which direct percutaneous puncture of the internal iliac artery aneurysm sac was performed under cone-beam CT guidance. PMID:25858522

  18. An Approximate Cone Beam Reconstruction Algorithm for Gantry-Tilted CT Using Tangential Filtering

    Ming Yan

    2006-01-01

    Full Text Available FDK algorithm is a well-known 3D (three-dimensional approximate algorithm for CT (computed tomography image reconstruction and is also known to suffer from considerable artifacts when the scanning cone angle is large. Recently, it has been improved by performing the ramp filtering along the tangential direction of the X-ray source helix for dealing with the large cone angle problem. In this paper, we present an FDK-type approximate reconstruction algorithm for gantry-tilted CT imaging. The proposed method improves the image reconstruction by filtering the projection data along a proper direction which is determined by CT parameters and gantry-tilted angle. As a result, the proposed algorithm for gantry-tilted CT reconstruction can provide more scanning flexibilities in clinical CT scanning and is efficient in computation. The performance of the proposed algorithm is evaluated with turbell clock phantom and thorax phantom and compared with FDK algorithm and a popular 2D (two-dimensional approximate algorithm. The results show that the proposed algorithm can achieve better image quality for gantry-tilted CT image reconstruction.

  19. Analytic image reconstruction from partial data for a single-scan cone-beam CT with scatter correction

    Min, Jonghwan; Pua, Rizza; Cho, Seungryong, E-mail: scho@kaist.ac.kr [Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 305-701 (Korea, Republic of); Kim, Insoo; Han, Bumsoo [EB Tech, Co., Ltd., 550 Yongsan-dong, Yuseong-gu, Daejeon 305-500 (Korea, Republic of)

    2015-11-15

    Purpose: A beam-blocker composed of multiple strips is a useful gadget for scatter correction and/or for dose reduction in cone-beam CT (CBCT). However, the use of such a beam-blocker would yield cone-beam data that can be challenging for accurate image reconstruction from a single scan in the filtered-backprojection framework. The focus of the work was to develop an analytic image reconstruction method for CBCT that can be directly applied to partially blocked cone-beam data in conjunction with the scatter correction. Methods: The authors developed a rebinned backprojection-filteration (BPF) algorithm for reconstructing images from the partially blocked cone-beam data in a circular scan. The authors also proposed a beam-blocking geometry considering data redundancy such that an efficient scatter estimate can be acquired and sufficient data for BPF image reconstruction can be secured at the same time from a single scan without using any blocker motion. Additionally, scatter correction method and noise reduction scheme have been developed. The authors have performed both simulation and experimental studies to validate the rebinned BPF algorithm for image reconstruction from partially blocked cone-beam data. Quantitative evaluations of the reconstructed image quality were performed in the experimental studies. Results: The simulation study revealed that the developed reconstruction algorithm successfully reconstructs the images from the partial cone-beam data. In the experimental study, the proposed method effectively corrected for the scatter in each projection and reconstructed scatter-corrected images from a single scan. Reduction of cupping artifacts and an enhancement of the image contrast have been demonstrated. The image contrast has increased by a factor of about 2, and the image accuracy in terms of root-mean-square-error with respect to the fan-beam CT image has increased by more than 30%. Conclusions: The authors have successfully demonstrated that the

  20. Five-dimensional motion compensation for respiratory and cardiac motion with cone-beam CT of the thorax region

    Sauppe, Sebastian; Hahn, Andreas; Brehm, Marcus; Paysan, Pascal; Seghers, Dieter; Kachelrieß, Marc

    2016-03-01

    We propose an adapted method of our previously published five-dimensional (5D) motion compensation (MoCo) algorithm1, developed for micro-CT imaging of small animals, to provide for the first time motion artifact-free 5D cone-beam CT (CBCT) images from a conventional flat detector-based CBCT scan of clinical patients. Image quality of retrospectively respiratory- and cardiac-gated volumes from flat detector CBCT scans is deteriorated by severe sparse projection artifacts. These artifacts further complicate motion estimation, as it is required for MoCo image reconstruction. For high quality 5D CBCT images at the same x-ray dose and the same number of projections as todays 3D CBCT we developed a double MoCo approach based on motion vector fields (MVFs) for respiratory and cardiac motion. In a first step our already published four-dimensional (4D) artifact-specific cyclic motion-compensation (acMoCo) approach is applied to compensate for the respiratory patient motion. With this information a cyclic phase-gated deformable heart registration algorithm is applied to the respiratory motion-compensated 4D CBCT data, thus resulting in cardiac MVFs. We apply these MVFs on double-gated images and thereby respiratory and cardiac motion-compensated 5D CBCT images are obtained. Our 5D MoCo approach processing patient data acquired with the TrueBeam 4D CBCT system (Varian Medical Systems). Our double MoCo approach turned out to be very efficient and removed nearly all streak artifacts due to making use of 100% of the projection data for each reconstructed frame. The 5D MoCo patient data show fine details and no motion blurring, even in regions close to the heart where motion is fastest.

  1. Four-dimensional cone beam CT reconstruction and enhancement using a temporal nonlocal means method

    Jia Xun; Tian Zhen; Lou Yifei; Sonke, Jan-Jakob; Jiang, Steve B. [Center for Advanced Radiotherapy Technologies and Department of Radiation Medicine and Applied Sciences, University of California San Diego, La Jolla, California 92037 (United States); School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, Georgia 30318 (United States); Department of Radiation Oncology, Netherlands Cancer Institute-Antoni van Leeuwenhoek Hospital, Plesmanlaan 121, 1066 CX Amsterdam (Netherlands); Center for Advanced Radiotherapy Technologies and Department of Radiation Medicine and Applied Sciences, University of California San Diego, La Jolla, California 92037 (United States)

    2012-09-15

    Purpose: Four-dimensional cone beam computed tomography (4D-CBCT) has been developed to provide respiratory phase-resolved volumetric imaging in image guided radiation therapy. Conventionally, it is reconstructed by first sorting the x-ray projections into multiple respiratory phase bins according to a breathing signal extracted either from the projection images or some external surrogates, and then reconstructing a 3D CBCT image in each phase bin independently using FDK algorithm. This method requires adequate number of projections for each phase, which can be achieved using a low gantry rotation or multiple gantry rotations. Inadequate number of projections in each phase bin results in low quality 4D-CBCT images with obvious streaking artifacts. 4D-CBCT images at different breathing phases share a lot of redundant information, because they represent the same anatomy captured at slightly different temporal points. Taking this redundancy along the temporal dimension into account can in principle facilitate the reconstruction in the situation of inadequate number of projection images. In this work, the authors propose two novel 4D-CBCT algorithms: an iterative reconstruction algorithm and an enhancement algorithm, utilizing a temporal nonlocal means (TNLM) method. Methods: The authors define a TNLM energy term for a given set of 4D-CBCT images. Minimization of this term favors those 4D-CBCT images such that any anatomical features at one spatial point at one phase can be found in a nearby spatial point at neighboring phases. 4D-CBCT reconstruction is achieved by minimizing a total energy containing a data fidelity term and the TNLM energy term. As for the image enhancement, 4D-CBCT images generated by the FDK algorithm are enhanced by minimizing the TNLM function while keeping the enhanced images close to the FDK results. A forward-backward splitting algorithm and a Gauss-Jacobi iteration method are employed to solve the problems. The algorithms implementation on

  2. Facial Asymmetry Evaluation in Juvenile Idiopathic Arthritis Patients Based On Cone-Beam Computed Tomography And 3D Photography

    Economou, Stalo; Stoustrup, Peter Bangsgaard; Kristensen, Kasper Dahl

    AIMS: The aim of the study was to assess the degree of and correlation between facial hard and soft tissue asymmetry in patients with juvenile idiopathic arthritis, identify valid soft tissue points for clinical examination and assess the smallest clinical detectable level of dentofacial asymmetr...

  3. Effect of light source instability on uniformity of 3D reconstructions from a cone beam optical CT scanner.

    Begg, J; Taylor, M L; Holloway, L; Kron, T; Franich, R D

    2014-12-01

    Temporally varying light intensity during acquisition of projection images in an optical CT scanner can potentially be misinterpreted as physical properties of the sample. This work investigated the impact of LED light source intensity instability on measured attenuation coefficients. Different scenarios were investigated by conducting one or both of the reference and data scans in a 'cold' scanner, where the light source intensity had not yet stabilised. Uniform samples were scanned to assess the impact on measured uniformity. The orange (590 nm) light source decreased in intensity by 29 % over the first 2 h, while the red (633 nm) decreased by 9 %. The rates of change of intensity at 2 h were 0.1 and 0.03 % respectively over a 5 min period-corresponding to the scan duration. The normalisation function of the reconstruction software does not fully account for the intensity differences and discrepancies remain. Attenuation coefficient inaccuracies of up to 8 % were observed for data reconstructed from projection images acquired with a cold scanner. Increased noise was observed for most cases where one or both of the scans was acquired without sufficient warm-up. The decrease in accuracy and increase in noise were most apparent for data reconstructed from reference and data scans acquired with a cold scanner on different days.

  4. Prediction of position estimation errors for 3D target trajetories estimated from cone-beam CT projections

    Poulsen, Per Rugaard; Cho, Byungchul; Keall, Paul

    2010-01-01

    . The mathematical formalism of the method includes an individualized measure of the position estimation error in terms of an estimated 1D Gaussian distribution for the unresolved target position[2]. The present study investigates how well this 1D Gaussian predicts the actual distribution of position estimation....... This finding indicates that individualized root-mean-square errors and 95% confidence intervals can be applied reliably to the estimated target trajectories....

  5. [The potential of cone beam computed tomography of the temporal bones in the patients presenting with otosclerosis].

    Karpishchenko, S A; Zubareva, A A; Filimonov, V N; Shavgulidze, M A; Azovtseva, E A

    The objective of the present study was to analyze the potential of cone beam computed tomography of the temporal bones in the patients presenting with otosclerosis for the detection of surgically significant specific structural features of the labyrinth wall of the tympanic cavity. More than 400 tomograms of the temporal bones were obtained with the use of a cone beam tomographwere available for the investigation during the period from 2012 till 2016. The study was carried out in several steps, viz. the search for the optimal (for the given instrument) position of the patient, the experimental stage, the retrospective analysis of the tomograms and the comparison of the temporal bones of different types (pneumatic, mixed, and sclerotic) in individual patients, the comparison of the results of cone beam computed tomography (CBCT) with the intraoperative observations, and the modification of the algorithm for the analysis of temporal bone cone beam tomograms. The study included a total of 16 patients (15 women at the age from 32 to 56 years and one managed 58 years) presenting with the clinical diagnosis of otosclerosis. The results of the study were used to elaborate the algorithm for the analysis of cone beam tomograms of the temporal bones to be performed inthe stage by stage manner including the qualitative analysis of tomograms, evaluation of their quantitative parameters and additional characteristics to be taken into consideration when planning the surgical interventions on the labyrinth wall and the tympanic cavity as a preparation for the stapedoplastic treatment. The results of CBCT obtained in the present study were compared with the surgical observations. The diagnostic sensitivity and specificity of the method were estimated to be 100% and 83% respectively. It is concluded that cone beam computed tomography can be employed as a component of the diagnostic algorithm prior to the planning of surgical interventions onthe medial wall of the tympanic cavity

  6. Value of cone-beam computed tomography in the process of diagnosis and management of disorders of the temporomandibular joint.

    de Boer, E W J; Dijkstra, P U; Stegenga, B; de Bont, L G M; Spijkervet, F K L

    2014-03-01

    The objective of this study was to assess the value of cone-beam computed tomographic (CT) images in the primary diagnosis and management of 128 outpatients with disorders of the temporomandibular joint (TMJ). Before a diagnosis was made and treatment planned, the history was taken, physical examination made, and the orthopantomogram studied. After assessment of the cone-beam CT, the oral and maxillofacial surgeon (specialist or resident) was allowed to revise the provisional primary diagnosis and management. The degree of certainty was rated by the clinician before and after the cone-beam CT had been assessed. The primary diagnosis was changed in 32 patients (25%), additional diagnostic procedures were changed in 57 (45%), and the treatment was changed in 15 (12%) (in 4 the treatment was changed to a (minimally) invasive procedure). A total of 74 patients (58%) had their diagnosis and management changed after the cone-beam CT had been assessed. Changes in diagnosis and management were clinically relevant in 9/32 and 9/61 patients, respectively. The clinician's certainty about the primary diagnosis increased after the cone-beam CT had been assessed in 57 patients. Logistic regression analysis showed that the odds in favour of changes in primary diagnosis and management increased when limited mandibular function was a primary symptom, the patient was taking medication for pain, and the articular eminence could not be assessed on OPT. Assessment of cone-beam CT led to changes in primary diagnosis and management in more than half the patients with disorders of the TMJ.

  7. Breathing Motion Analysis Based on Cone Beam CT Images%基于Cone Beam CT图像的呼吸运动分析

    白相志; 周付根

    2008-01-01

    呼吸运动是有一定规律性的运动,传统呼吸运动模型用公式描述,不能准确反映不同病人的特点或同一病人不同时期的特点,无法满足实时准确分析的需要.为此,我们提出了一种通过跟踪病人自由呼吸状态下所采集的Cone Beam CT图像序列中的横隔膜的运动来建立病人呼吸运动模型的方法.该方法建立的模型与传统的呼吸运动理论模型非常相似,证明了它是可行且有效的,同时该方法更能实时准确地反映病人的呼吸运动规律,具有很高的临床实用价值.

  8. Development of an optimization concept for arc-modulated cone beam therapy

    Ulrich, Silke; Nill, Simeon; Oelfke, Uwe [Department of Medical Physics in Radiation Therapy, Deutsches Krebsforschungszentrum (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg (Germany)

    2007-07-21

    In this paper, we propose an optimization concept for a rotation therapy technique which is referred to as arc-modulated cone beam therapy (AMCBT). The aim is a reduction of the treatment time while achieving a treatment plan quality equal to or better than that of IMRT. Therefore, the complete dose is delivered in one single gantry rotation and the beam is modulated by a multileaf collimator. The degrees of freedom are the field shapes and weights for a predefined number of beam directions. In the new optimization loop, the beam weights are determined by a gradient algorithm and the field shapes by a tabu search algorithm. We present treatment plans for AMCBT for two clinical cases. In comparison to step-and-shoot IMRT treatment plans, it was possible by AMCBT to achieve dose distributions with a better dose conformity to the target and a lower mean dose for the most relevant organ at risk. Furthermore, the number of applied monitor units was reduced for AMCBT in comparison to IMRT treatment plans.

  9. Clinical implementation of 3D printing in the construction of patient specific bolus for electron beam radiotherapy for non-melanoma skin cancer

    Canters, R.A.M.; Lips, I.M.; Wendling, M.; Kusters, M.; Zeeland, M. van; Gerritsen, R.M.; Poortmans, P.; Verhoef, C.G.

    2016-01-01

    BACKGROUND AND PURPOSE: Creating an individualized tissue equivalent material build-up (i.e. bolus) for electron beam radiation therapy is complex and highly labour-intensive. We implemented a new clinical workflow in which 3D printing technology is used to create the bolus. MATERIAL AND METHODS: A

  10. TH-A-18C-02: An Electrostatic Model for Assessment of Joint Space Morphology in Cone-Beam CT

    Cao, Q; Thawait, G; Gang, G; Zbijewski, W; Riegel, T; Demehri, S; Siewerdsen, J [Johns Hopkins University, Baltimore, MD (United States)

    2014-06-15

    Purpose: High-resolution cone-beam CT (CBCT) of the extremities presents a potentially valuable basis for image-based biomarkers of arthritis, trauma, and risk of injury. We present a new method for 3D joint space analysis that exploits the high isotropic spatial resolution of CBCT and is sensitive to small changes in disease-related morphology. Methods: The approach uses an “electrostatic” model in which joint surfaces (e.g., distal femur and proximal tibia) are labeled as charge densities between which the electric field is solved by approximation to the Laplace equation. The method yields a unique solution determined by the field lines across the “capacitor” and is hypothesized to be more sensitive than conventional (Sharp) scores and immune to degeneracies that limit simple distance-along-axis or closest-point analysis. The algorithm was validated in CBCT phantom images and applied in two clinical scenarios: osteoarthritis (OA, change in loadbearing tibiofemoral joint space); and assessment of injury risk (correlation of 3D joint space to tibial slope). Results: Joint space maps computed from the electrostatic model were accurate to within the voxel size (0.26 mm). The method highlighted subtle regions of morphological change that would likely be missed by conventional scalar metrics. Regions of subtle cartilage erosion were well quantified, and the method confidently discriminated OA and non-OA cohorts. 3D joint space maps correlated well with tibial slope and provide a new basis for principal component analysis of loadbearing injury risk. Runtime was less than 5 min (235×235×121 voxel subvolume in Matlab). Conclusion: A new method for joint space assessment was reported as a possible image-based biomarker of subtle articular change. The algorithm yields accurate quantitation of the joint in a manner that is robust against operator and patient setup variation. The method shows promising initial results in ongoing trials of CBCT in osteoarthritis

  11. Patient Position Verification and Corrective Evaluation Using Cone Beam Computed Tomography (CBCT) in Intensity modulated Radiation Therapy

    Do, Gyeong Min; Jeong, Deok Yang; Kim, Young Bum [Dept. of Radiation Oncology, Korea University Guro Hospital, Seoul (Korea, Republic of)

    2009-09-15

    Cone beam computed tomography (CBCT) using an on board imager (OBI) can check the movement and setup error in patient position and target volume by comparing with the image of computer simulation treatment in real.time during patient treatment. Thus, this study purposed to check the change and movement of patient position and target volume using CBCT in IMRT and calculate difference from the treatment plan, and then to correct the position using an automated match system and to test the accuracy of position correction using an electronic portal imaging device (EPID) and examine the usefulness of CBCT in IMRT and the accuracy of the automatic match system. The subjects of this study were 3 head and neck patients and 1 pelvis patient sampled from IMRT patients treated in our hospital. In order to investigate the movement of treatment position and resultant displacement of irradiated volume, we took CBCT using OBI mounted on the linear accelerator. Before each IMRT treatment, we took CBCT and checked difference from the treatment plan by coordinate by comparing it with the image of CT simulation. Then, we made correction through the automatic match system of 3D/3D match to match the treatment plan, and verified and evaluated using electronic portal imaging device. When CBCT was compared with the image of CT simulation before treatment, the average difference by coordinate in the head and neck was 0.99 mm vertically, 1.14 mm longitudinally, 4.91 mm laterally, and 1.07 degrees in the rotational direction, showing somewhat insignificant differences by part. In testing after correction, when the image from the electronic portal imaging device was compared with DRR image, it was found that correction had been made accurately with error less than 0.5 mm. By comparing a CBCT image before treatment with a 3D image reconstructed into a volume instead of a 2D image for the patient's setup error and change in the position of the organs and the target, we could measure and

  12. Small field dose delivery evaluations using cone beam optical computed tomography-based polymer gel dosimetry

    Timothy Olding

    2011-01-01

    Full Text Available This paper explores the combination of cone beam optical computed tomography with an N-isopropylacrylamide (NIPAM-based polymer gel dosimeter for three-dimensional dose imaging of small field deliveries. Initial investigations indicate that cone beam optical imaging of polymer gels is complicated by scattered stray light perturbation. This can lead to significant dosimetry failures in comparison to dose readout by magnetic resonance imaging (MRI. For example, only 60% of the voxels from an optical CT dose readout of a 1 l dosimeter passed a two-dimensional Low′s gamma test (at a 3%, 3 mm criteria, relative to a treatment plan for a well-characterized pencil beam delivery. When the same dosimeter was probed by MRI, a 93% pass rate was observed. The optical dose measurement was improved after modifications to the dosimeter preparation, matching its performance with the imaging capabilities of the scanner. With the new dosimeter preparation, 99.7% of the optical CT voxels passed a Low′s gamma test at the 3%, 3 mm criteria and 92.7% at a 2%, 2 mm criteria. The fitted interjar dose responses of a small sample set of modified dosimeters prepared (a from the same gel batch and (b from different gel batches prepared on the same day were found to be in agreement to within 3.6% and 3.8%, respectively, over the full dose range. Without drawing any statistical conclusions, this experiment gives a preliminary indication that intrabatch or interbatch NIPAM dosimeters prepared on the same day should be suitable for dose sensitivity calibration.

  13. Performance evaluation of the backprojection filtered (BPF) algorithm in circular fan-beam and cone-beam CT

    2006-01-01

    In this article we introduce an exact backprojecfion filtered (BPF) type reconstruction algorithm for cone-beam scans based on Zou and Pan's work. The algorithm can reconstruct images using only the projection data passing through the parallel PI-line segments in reduced scans. Computer simulations and practical experiments are carried out to evaluate this algorithm. The BPF algorithm has a higher computational efficiency than the famous FDK algorithm. The BPF algorithm is evaluated using the practical CT projection data on a 450 keV X-ray CT system with a flat-panel detector (FPD). From the practical experiments, we get the spatial resolution of this CT system. The algorithm could achieve the spatial resolution of 2.4 lp/mm and satisfies the practical applications in industrial CT inspection.

  14. Using Quasi-3D OSIRIS simulations of LWFA to study generating high brightness electron beams using ionization and density downramp injection

    Dalichaouch, Thamine; Davidson, Asher; Xu, Xinlu; Yu, Peicheng; Tsung, Frank; Mori, Warren; Li, Fei; Zhang, Chaojie; Lu, Wei; Vieira, Jorge; Fonseca, Ricardo

    2016-10-01

    In the past few decades, there has been much progress in theory, simulation, and experiment towards using Laser wakefield acceleration (LWFA) as the basis for designing and building compact x-ray free-electron-lasers (XFEL) as well as a next generation linear collider. Recently, ionization injection and density downramp injection have been proposed and demonstrated as a controllable injection scheme for creating higher quality and ultra-bright relativistic electron beams using LWFA. However, full-3D simulations of plasma-based accelerators are computationally intensive, sometimes taking 100 millions of core-hours on today's computers. A more efficient quasi-3D algorithm was developed and implemented into OSIRIS using a particle-in-cell description with a charge conserving current deposition scheme in r - z and a gridless Fourier expansion in ϕ. Due to the azimuthal symmetry in LWFA, quasi-3D simulations are computationally more efficient than 3D cartesian simulations since only the first few harmonics in are needed ϕ to capture the 3D physics of LWFA. Using the quasi-3D approach, we present preliminary results of ionization and down ramp triggered injection and compare the results against 3D LWFA simulations. This work was supported by DOE and NSF.

  15. A comparative study for spatial resolution and subjective image characteristics of a multi-slice CT and a cone-beam CT for dental use

    Watanabe, Hiroshi, E-mail: hiro.orad@tmd.ac.jp [Oral and Maxillofacial Radiology, Division of Oral Restitution, Graduate School, Tokyo Medical and Dental University, 5-45 Yushima 1-chome, Bunkyo-ku, Tokyo 1138549 (Japan); Honda, Eiichi [Oral and Maxillofacial Radiology, Division of Oral Health Sciences, The University of Tokushima Graduate School (Japan); Tetsumura, Akemi; Kurabayashi, Tohru [Oral and Maxillofacial Radiology, Division of Oral Restitution, Graduate School, Tokyo Medical and Dental University, 5-45 Yushima 1-chome, Bunkyo-ku, Tokyo 1138549 (Japan)

    2011-03-15

    Purpose: Multi-slice CT (MSCT) and cone-beam CT (CBCT) are widely used in dental practice. This study compared the spatial resolution of these CT systems to elucidate which CT modalities should be selected for various clinical cases. Materials and methods: As MSCT and CBCT apparatuses, Somatom Sensation 64 and 3D Accuitomo instruments, respectively, were used. As an objective evaluation of spatial resolution of these CT systems, modulation transfer function (MTF) analysis was performed employing an over-sampling method. The results of MTF analysis were confirmed with a line-pair test using CATPHAN. As a subjective evaluation, a microstructure visualization ability study was performed using a Jcl:SD rat and a head CT phantom. Results: MTF analysis showed that for the in-plane direction, the z-axis ultrahigh resolution mode (zUHR) of the Sensation 64 and 3D Accuitomo instruments had higher spatial resolutions than the conventional mode (64x) of the Sensation 64, but for the longitudinal direction, the 3D Accuitomo had clearly higher spatial resolution than either mode of the Sensation 64. A line-pair test study and microstructure visualization ability studies confirmed the results for MTF analysis. However, images of the rat and the CT phantom revealed that the 3D Accuitomo demonstrated the failure to visualize the soft tissues along with aliasing and beam-hardening artifacts, which were not observed in the Sensation 64. Conclusions: This study successfully applied spatial resolution analysis using MSCT and CBCT systems in a comparative manner. These findings could help in deciding which CT modality should be selected for various clinical cases.

  16. Clinical use of cone beam CT in impacted maxillary tooth extraction and artifistulation%锥形束CT定位埋伏牙的临床应用

    董辉; 冯春丽; 孙蕾; 祁森荣; 夏登胜

    2011-01-01

    目的 探讨锥形束CT影像和三维重建技术在辅助埋伏牙拔除和正畸开窗牙牵引术中的作用.方法 选择53颗常规曲面断层片难以确定埋伏牙空间位置的患者进行锥形束CT扫描,其中对5例复杂埋伏牙的CT图像进行三维重建.45例埋伏牙依据CT图像选择不同手术入路行拔牙术,8例埋伏牙采用颌骨开窗牵引术.结果 螺旋CT影像对正确选择埋伏牙拔除的手术入路具有良好的指导作用;CT三维重建图像能清楚地显示埋伏牙的牙体形态、唇腭向位置以及和邻牙的关系,正确指导手术开窗牵引的入路和开窗牵引装置的固定.结论 锥形束CT和三维重建技术在显示埋伏牙的位置和牙体形态上明显优于传统的曲面断层和根尖片.%Objective To evaluate the value of cone beam CT and three-dimensional reconstruction in impacted maxillary tooth extraction and artifistulation. Methods Fifty-three patients with impacted maxillary teeth were included and examined by cone beam CT, and 3D reconstruction was conducted in five of them . Results The cone beam CT images clearly denmonstrated the location of the teeth and provided help in the impacted tooth extraction. The threedimensional reconstruction technique guided and simplified the procedure of artifistulation. Conclusion Cone beam CT has more advantages in assistance of impacted tooth extraction and artifistulation in orthodontics compared with traditional panoramic radiography.

  17. The combination of digital surface scanners and cone beam computed tomography technology for guided implant surgery using 3Shape implant studio software: a case history report.

    Lanis, Alejandro; Álvarez Del Canto, Orlando

    2015-01-01

    The incorporation of virtual engineering into dentistry and the digitization of information are providing new perspectives and innovative alternatives for dental treatment modalities. The use of digital surface scanners with surgical planning software allows for the combination of the radiographic, prosthetic, surgical, and laboratory fields under a common virtual scenario, permitting complete digital treatment planning. In this article, the authors present a clinical case in which a guided implant surgery was performed based on a complete digital surgical plan combining the information from a cone beam computed tomography scan and the virtual simulation obtained from the 3Shape TRIOS intraoral surface scanner. The information was imported to and combined in the 3Shape Implant Studio software for guided implant surgery planning. A surgical guide was obtained by a 3D printer, and the surgical procedure was done using the Biohorizons Guided Surgery Kit and its protocol.

  18. Palatal bone thickness measured by palatal index method using cone-beam computed tomography in nonorthodontic patients for placement of mini-implants

    W S Manjula

    2015-01-01

    Full Text Available Introduction: The purpose of this study was to compare the bone thickness of the palatal areas in different palatal index (PI groups. Materials and Methods: Cone-beam computed tomography scans of 10 subjects were selected with a mean age group of 18 years. The measurements of palatal bone thickness were made at 36 sites using CareStream 3D Imaging software. The PI was measured using Korkhaus ratio (palatal height/palatal width. One-way analysis of variance was used to analyze intergroup differences, as well as the PI difference. Results: Bone thickness was higher in the anterior region than in the middle and posterior regions P<0.001. Furthermore, significant differences were found among the midline, medial, and lateral areas of the palate. Conclusions: These findings might be helpful for clinicians to enhance the successful use of temporary anchorage devices in the palate.

  19. Validation of a novel semi-automated method for three-dimensional surface rendering of condyles using cone beam computed tomography data.

    Xi, T; van Loon, B; Fudalej, P; Bergé, S; Swennen, G; Maal, T

    2013-08-01

    Morphological changes of the condyles are often observed following orthognathic surgery. In addition to clinical assessment, radiographic evaluation of the condyles is required to distinguish the physiological condylar remodelling from pathological condylar resorption. The low contrast resolution and distortion of greyscale values in cone beam computed tomography (CBCT) scans have impeded an accurate three-dimensional (3D) rendering of the condyles. The current study proposes a novel semi-automated method for 3D rendering of condyles using CBCT datasets, and provides a clinical validation of this method. Ten patients were scanned using a standard CBCT scanning protocol. After defining the volume of interest, a greyscale cut-off value was selected to allow an automatic reconstruction of the condylar outline. The condylar contour was further enhanced manually by two independent observers to correct for the under- and over-contoured voxels. Volumetric measurements and surface distance maps of the condyles were computed. The mean within-observer and between-observer differences in condylar volume were 8.62 mm(3) and 6.13 mm(3), respectively. The mean discrepancy between intra- and inter-observer distance maps of the condylar surface was 0.22 mm and 0.13 mm, respectively. This novel method provides a reproducible tool for the 3D rendering of condyles, allowing longitudinal follow-up and quantitative analysis of condylar changes following orthognathic surgery.

  20. Development of Kilovoltage X-ray Dosimetry Methods and Their Application to Cone Beam Computed Tomography

    Lawless, Michael J.

    The increase in popularity of pre-treatment imaging procedures in radiation therapy, such as kilovoltage cone beam computed tomography (CBCT), has been accompanied by an increase in the dose delivered to the patient from these imaging procedures. The measurement of dose from CBCT scans is complicated, as currently available kilovoltage dosimetry protocols are based on air-kerma standards and radiation detectors exhibit large energy responses at the low photon energies used in the imaging procedures. This work aims to provide the tools and methodology needed to measure the dose from these scans more accurately and precisely. Through the use of a validated Monte Carlo (MC) model of the moderately filtered (M-series) x-ray beams at the University of Wisconsin Accredited Dosimetry Calibration Laboratory, dose-to-water rates were obtained in a water phantom for the M-series x-ray beams with tube potentials from 40-250 kVp. The resulting dose-to-water rates were consistent with previously established methods, but had significantly reduced uncertainties. While detectors are commonly used to measure dose in phantom, previous investigations of the energy response of common detectors in the kilovoltage energy range have been limited to in-air geometries. The newly determined dose-to-water rates were used to characterize the in-phantom energy and depth response of thermoluminescent dosimeters and ionization chambers. When compared to previous investigations of the in-air detector response, the impact of scatter and absorption of the photon beam by the water medium was found to have a significant impact on the response of certain detectors. The dose to water in the NIST-traceable M-series x-ray beams was transferred to clinical CBCT beams and the resulting doses agreed with other dose-to-water measurement techniques. The dose to water in the CBCT beams was used to characterize the energy and depth responses of a number of detectors. The energy response in the CBCT beams agreed

  1. Establishment of reference mandibular plane for anterior alveolar morphology evaluation using cone beam computed tomography

    Rong-yang WANG; Min HAN; Hong LIU; Chun-ling WANG; Hong-hong XIAN; Lei ZHANG; Shi-jie ZHANG; Dong-xu LIU

    2012-01-01

    To propose a method of establishing the reference mandibular plane (MP),which could be reestablished according to the coordinates of the reference points,and then facilitate the assessment of anterior alveolar morphology using cone beam computed tomography (CBCT),sixty patients with bimaxillary protrusion were randomly selected and CBCT scans were taken.The CBCT scans were transferred to Materialism's interactive medical image control system 10.01 (MIMICS 10.01),and three dimensional models of the entire jaws were constructed.Reference points determining the reference MP were positioned in the coronal,axial,sagittal windows,and the points were exactly located by recording their coordinates in the interfaces of software.The reference MP provided high intra-observer reliability (Pearson's r 0.992 to 0.999),and inter-observer reliability (intra-class correlation coefficients (ICCs)0.996 to 0.999).

  2. Cone-beam computed tomography exploration and surgical management of palatal, inverted, and impacted mesiodens.

    Omami, Mounir; Chokri, Abdellatif; Hentati, Hajer; Selmi, Jamil

    2015-09-01

    Supernumerary teeth are extra teeth or toothlike structures which may have either erupted or unerupted in addition to the 20 deciduous teeth and the 32 permanent teeth. Mesiodens is one of these located in the midline between the two central incisors. Their presence may give rise to a variety of clinical problems. This paper describes a rare case of palatal placed, inverted and impacted mesiodens associated to two supernumerary teeth which were detected during a radiographic examination for delayed eruption of permanent central incisors in the case of a healthy 8-year-old girl monitored at the oral surgery service while discussing the usefulness of cone beam computed tomography for accurate diagnosis and management.

  3. Cone-beam computed tomography exploration and surgical management of palatal, inverted, and impacted mesiodens

    Mounir Omami

    2015-01-01

    Full Text Available Supernumerary teeth are extra teeth or toothlike structures which may have either erupted or unerupted in addition to the 20 deciduous teeth and the 32 permanent teeth. Mesiodens is one of these located in the midline between the two central incisors. Their presence may give rise to a variety of clinical problems. This paper describes a rare case of palatal placed, inverted and impacted mesiodens associated to two supernumerary teeth which were detected during a radiographic examination for delayed eruption of permanent central incisors in the case of a healthy 8-year-old girl monitored at the oral surgery service while discussing the usefulness of cone beam computed tomography for accurate diagnosis and management.

  4. Cone Beam Computed Tomography (CBCT) in the Field of Interventional Oncology of the Liver

    Bapst, Blanche, E-mail: blanchebapst@hotmail.com; Lagadec, Matthieu, E-mail: matthieu.lagadec@bjn.aphp.fr [Beaujon Hospital, University Hospitals Paris Nord Val de Seine, Beaujon, Department of Radiology (France); Breguet, Romain, E-mail: romain.breguet@hcuge.ch [University Hospital of Geneva (Switzerland); Vilgrain, Valérie, E-mail: Valerie.vilgrain@bjn.aphp.fr; Ronot, Maxime, E-mail: maxime.ronot@bjn.aphp.fr [Beaujon Hospital, University Hospitals Paris Nord Val de Seine, Beaujon, Department of Radiology (France)

    2016-01-15

    Cone beam computed tomography (CBCT) is an imaging modality that provides computed tomographic images using a rotational C-arm equipped with a flat panel detector as part of the Angiography suite. The aim of this technique is to provide additional information to conventional 2D imaging to improve the performance of interventional liver oncology procedures (intraarterial treatments such as chemoembolization or selective internal radiation therapy, and percutaneous tumor ablation). CBCT provides accurate tumor detection and targeting, periprocedural guidance, and post-procedural evaluation of treatment success. This technique can be performed during intraarterial or intravenous contrast agent administration with various acquisition protocols to highlight liver tumors, liver vessels, or the liver parenchyma. The purpose of this review is to present an extensive overview of published data on CBCT in interventional oncology of the liver, for both percutaneous ablation and intraarterial procedures.

  5. Robust scatter correction method for cone-beam CT using an interlacing-slit plate

    Huang, Kuidong; Zhang, Dinghua; Zhang, Hua; Shi, Wenlong

    2015-01-01

    Cone-beam computed tomography (CBCT) has been widely used in medical imaging and industrial nondestructive testing, but the presence of scattered radiation will cause significant reduction of image quality. In this article, a robust scatter correction method for CBCT using an interlacing-slit plate (ISP) is carried out for convenient practice. Firstly, a Gaussian filtering method is proposed to compensate the missing data of the inner scatter image, and simultaneously avoid too-large values of calculated inner scatter and smooth the inner scatter field. Secondly, an interlacing-slit scan without detector gain correction is carried out to enhance the practicality and convenience of the scatter correction method. Finally, a denoising step for scatter-corrected projection images is added in the process flow to control the noise amplification. The experimental results show that the improved method can not only make the scatter correction more robust and convenient, but also achieve a good quality of scatter-corre...

  6. Cone beam CT for diagnosis and treatment planning in trauma cases.

    Palomo, Leena; Palomo, J Martin

    2009-10-01

    Three-dimensional imaging offers many advantages in making diagnoses and planning treatment. This article focuses on cone beam CT (CBCT) for making diagnoses and planning treatment in trauma-related cases. CBCT equipment is smaller and less expensive than traditional medical CT equipment and is tailored to address challenges specific to the dentoalveolar environment. Like medical CT, CBCT offers a three-dimensional view that conventional two-dimensional dental radiography fails to provide. CBCT combines the strengths of medical CT with those of conventional dental radiography to accommodate unique diagnostic and treatment-planning applications that have particular utility in dentoalveolar trauma cases. CBCT is useful, for example, in identifying tooth fractures relative to surrounding alveolar bone, in determining alveolar fracture location and morphology, in analyzing ridge-defect height and width, and in imaging temporomandibular joints. Treatment-planning applications include those involving extraction of fractured teeth, placement of implants, exposure of impacted teeth, and analyses of airways.

  7. Diagnosis and Treatment of a Type III Dens Invagination Using Cone-Beam Computed Tomography

    Bahmani, Mohsen; Adl, Alireza; Javanmardi, Samane; Naghizadeh, Sina

    2016-01-01

    A 20-year-old man presented with the history of pain and swelling in the anterior maxillary segment. The periapical radiography was indicative of a dental anomaly in right maxillary lateral incisor. Due to the insufficient information from conventional radiography, cone-beam computed tomography (CBCT) was ordered. CBCT showed apical root resorption, large apical lucency and two separate canals with distinct apical foramen (Oehlers type III dens invagination). The CBCT image was used as a guide for dentine removal with an ultrasonic tip. Conventional root canal therapy was done using lateral compaction technique. One-and two-year follow-up radiographies revealed periapical repair and absence of symptoms. PMID:27790268

  8. Multiple idiopathic external and internal resorption: Case report with cone-beam computed tomography findings

    Celikten, Berkan; Uzuntas, Ceren Feriha; Kurt, Hakan [Faculty of Dentistry, Ankara University, Ankara (Turkmenistan)

    2014-12-15

    Root resorption is loss of dental hard tissue as a result of clastic activities. The dental hard tissue of permanent teeth does not normally undergo resorption, except in cases of inflammation or trauma. However, there are rare cases of tooth resorption of an unknown cause, known as 'idiopathic root resorption.' This report would discuss a rare case of multiple idiopathic resorption in the permanent maxillary and mandibular teeth of an otherwise healthy 36-year-old male patient. In addition to a clinical examination, the patient was imaged using conventional radiography and cone-beam computed tomography (CBCT). The examinations revealed multiple external and internal resorption of the teeth in all four quadrants of the jaws with an unknown cause. Multiple root resorption is a rare clinical phenomenon that should be examined using different radiographic modalities. Cross-sectional CBCT is useful in the diagnosis and examination of such lesions.

  9. Multiple idiopathic external and internal resorption: Case report with cone-beam computed tomography findings.

    Celikten, Berkan; Uzuntas, Ceren Feriha; Kurt, Hakan

    2014-12-01

    Root resorption is loss of dental hard tissue as a result of clastic activities. The dental hard tissue of permanent teeth does not normally undergo resorption, except in cases of inflammation or trauma. However, there are rare cases of tooth resorption of an unknown cause, known as "idiopathic root resorption." This report would discuss a rare case of multiple idiopathic resorption in the permanent maxillary and mandibular teeth of an otherwise healthy 36-year-old male patient. In addition to a clinical examination, the patient was imaged using conventional radiography and cone-beam computed tomography (CBCT). The examinations revealed multiple external and internal resorption of the teeth in all four quadrants of the jaws with an unknown cause. Multiple root resorption is a rare clinical phenomenon that should be examined using different radiographic modalities. Cross-sectional CBCT is useful in the diagnosis and examination of such lesions.

  10. Developmental salivary gland depression in the ascending mandibular ramous: A cone-beam computed tomography study

    Chen, Christine A.; Ahn, Yoon Hee; Odell, Scott; Mupparapu, Mel; Graham, David Mattew [University of Pennsylvania School of Dental Medicine, Philadelphia (United States)

    2016-09-15

    A static, unilateral, and focal bone depression located lingually within the ascending ramous, identical to the Stafne's bone cavity of the angle of the mandible, is being reported. During development of the mandible, submandibular gland inclusion may lead to the formation of a lingual concavity, which could contain fatty tissue, blood vessels, or soft tissue. However, similar occurrences in the ascending ramous at the level of the parotid gland are extremely rare. Similar cases were previously reported in dry, excavated mandibles, and 3 cases were reported in living patients. A 52-year-old African American male patient was seen for pain in the mandibular teeth. Panoramic radiography showed an unusual concavity within the left ascending ramous. Cone-beam computed tomography confirmed this incidental finding. The patient was cleared for the extraction of non-restorable teeth and scheduled for annual follow-up.

  11. Cone-beam computed tomography in endodontics: are we there yet?

    Nesari, Royeen; Rossman, Louis E; Kratchman, Samuel I

    2009-01-01

    From digital radiography units to office computer systems, there are several pieces of equipment that make up today's high-tech dental office. Recently, advances in dental imaging have allowed cone-beam computed tomography (CBCT), which is a form of 3-dimensional radiography, to gain increasing popularity as another major office component. In consideration of the current economic conditions, cost has become a definite obstacle for many practitioners. With several brands available, this technology has nonetheless generated considerable attention for use in presurgical treatment planning and diagnosis. However, is there enough evidence for its use in endodontics? This article aims to bring to light the many exciting features of CBCT, including its operation, impact, and feasibility in endodontics.

  12. Cone-Beam Computed Tomography contrast validation of an artificial periodontal phantom for use in endodontics.

    Michetti, Jerome; Basarab, Adrian; Tran, Michel; Diemer, Franck; Kouame, Denis

    2015-01-01

    Validation of image processing techniques such as endodontic segmentations in cone-beam computed tomography (CBCT) is a challenging issue because of the lack of ground truth in in vivo experiments. The purpose of our study was to design an artificial surrounding tissues phantom able to provide CBCT image quality of real extracted teeth, similar to in vivo conditions. Note that these extracted teeth could be previously scanned using micro computed tomography (μCT) to access true quantitative measurements of the root canal anatomy. Different design settings are assessed in our study by comparison to in vivo images, in terms of the contrast-to-noise ratio (CNR) obtained between different anatomical structures. Concerning the root canal and the dentine, the best design setup allowed our phantom to provide a CNR difference of only 3% compared to clinical cases.

  13. Cone Beam Computed Tomographic Evaluation and Diagnosis of Mandibular First Molar with 6 Canals

    Shiraz Pasha

    2016-01-01

    Full Text Available Root canal treatment of tooth with aberrant root canal morphology is very challenging. So thorough knowledge of both the external and internal anatomy of teeth is an important aspect of root canal treatment. With the advancement in technology it is imperative to use modern diagnostic tools such as magnification devices, CBCT, microscopes, and RVG to confirm the presence of these aberrant configurations. However, in everyday endodontic practice, clinicians have to treat teeth with atypical configurations for root canal treatment to be successful. This case report presents the management of a mandibular first molar with six root canals, four in mesial and two in distal root, and also emphasizes the use and importance of Cone Beam Computed Tomography (CBCT as a diagnostic tool in endodontics.

  14. A Model-Based Scatter Artifacts Correction for Cone Beam CT

    Zhao, Wei; Zhu, Jun; Wang, Luyao; Xing, Lei

    2016-01-01

    The purpose of this work is to provide a fast and accurate scatter artifacts correction algorithm for cone beam CT (CBCT) imaging. The method starts with an estimation of coarse scatter profiles for a set of CBCT data in either image domain or projection domain. A denoising algorithm designed specifically for Poisson signals is then applied to derive the final scatter distribution. Qualitative and quantitative evaluations using thorax and abdomen phantoms with Monte Carlo (MC) simulations, experimental Catphan phantom data, and in vivo human data acquired for a clinical image guided radiation therapy were performed. Results show that the proposed algorithm can significantly reduce scatter artifacts and recover the correct HU in either projection domain or image domain. For the MC thorax phantom study, four components segmentation yield the best results, while the results of three components segmentation are still acceptable. For the Catphan phantom data, the mean value over all pixels in the residual image is...

  15. Cone Beam CT在口腔种植外科中的应用

    陈宁

    2011-01-01

    Cone beam CT技术已成为口腔颌面部疾病诊断和临床研究的重要方法,与常规的平片以及口腔全景片相比有着许多明显的优势。在口腔种植外科的应用中能够提供精确的、定量的、三维图像信息,这对于解剖学研究、临床评价、术前诊断和随访观察是非常重要的,可以有效地提高种植的成功率,避免并发症。

  16. Limited-angle reverse helical cone-beam CT for pipeline with low rank decomposition

    Wu, Dong; Zeng, Li

    2014-10-01

    In this paper, tomographic imaging of pipeline in service by cone-beam computed tomography (CBCT) is studied. With the developed scanning strategy and image model, the quality of reconstructed image is improved. First, a limited-angle reverse helical scanning strategy based on C-arm computed tomography (C-arm CT) is developed for the projection data acquisition of pipeline in service. Then, an image model which considering the resemblance among slices of pipeline is developed. Finally, split Bregman method based algorithm is implemented in solving the model aforementioned. Preliminary results of simulation experiments show that the projection data acquisition strategy and reconstruction method are efficient and feasible, and our method is superior to Feldkamp-Davis-Kress (FDK) algorithm and simultaneous algebraic reconstruction technique (SART).

  17. Unilateral Fusion of Maxillary Lateral Incisor: Diagnosis Using Cone Beam Computed Tomography

    Iury Oliveira Castro

    2014-01-01

    Full Text Available Objective. The objective of this paper is to report a dental fusion case focusing on clinical and radiographic features for the diagnosis. Method. To report a case of right maxillary lateral incisor fusion and a supernumerary tooth, the anatomy of the root canal and dental united portion were assessed by cone beam computed tomography (CBCT. Results. The clinical examination showed dental juxtaposition with the absence of interdental papilla and esthetic impairment in the right maxillary lateral incisor region. The periapical radiography did not provide enough information for the differential diagnosis due to the inherent limitations of this technique. CBCT confirmed the presence of tooth fusion. Conclusion. CBCT examination supports the diagnosis and provides both the identification of changes in tooth development and the visualization of their extent and limits.

  18. Maxillary first molar with seven root canals diagnosed with cone-beam computed tomography scanning

    Anil Munavalli

    2015-01-01

    Full Text Available Nonsurgical endodontic therapy of a right maxillary first molar with three roots and seven root canals. This unusual morphology was diagnosed using a dental operating microscope (DOM and confirmed with the help of cone-beam computed tomography (CBCT images. CBCT axial images showed that both the palatal and distobuccal root have a Vertucci type II canal pattern, whereas the mesiobuccal root showed a Sert and Bayirli type XVIII canal configuration. The use of a DOM and CBCT imaging in endodontically challenging cases can facilitate a better understanding of the complex root canal anatomy, which ultimately enables the clinician to explore the root canal system and clean, shape, and obturate it more efficiently.

  19. Calculating tumor trajectory and dose-of-the-day using cone-beam CT projections

    Jones, Bernard L; Miften, Moyed

    2015-01-01

    Purpose: Cone-beam CT (CBCT) projection images provide anatomical data in real-time over several respiratory cycles, forming a comprehensive picture of tumor movement. We developed and validated a method which uses these projections to determine the trajectory of and dose to highly mobile tumors during each fraction of treatment. Methods: CBCT images of a respiration phantom were acquired, the trajectory of which mimicked a lung tumor with high amplitude (up to 2.5 cm) and hysteresis. A template-matching algorithm was used to identify the location of a steel BB in each CBCT projection, and a Gaussian probability density function for the absolute BB position was calculated which best fit the observed trajectory of the BB in the imager geometry. Two modifications of the trajectory reconstruction were investigated: first, using respiratory phase information to refine the trajectory estimation (Phase), and second, using the Monte Carlo (MC) method to sample the estimated Gaussian tumor position distribution. Resu...

  20. Cone Beam Computed Tomography (CBCT Features of a Rare Fibro-Osseous Lesion: A Case Report

    Mahrokh Imanimoghaddam

    2013-03-01

    Full Text Available Cone beam computed tomography is a useful technique for imaging the craniofacial lesions. It produces more realistic images that facilitate interpretation. Juvenile ossifying fibroma (JOF is a rare and benign fibro-osseous neoplasm that arises within the craniofacial bones, especially in the maxilla. Mandibular lesions can be seen in 10% of the cases.In both jaws, it has a predilection for the premolar and molar regions (it is mostly seen in premolar and molar regions. Radiographically, it can be present as a radiolucent, mixed or radiopaque lesion. Radiodensity varies from purely radiolucent masses to mixed densities with prominent radiopacity as the lesion matures.This case report highlights a JOF with large foci of odontome-like radiopacities in a 6-year-old boy's mandibular anterior region. The location of the lesion in the anterior mandible and comparatively rapid formation of large odontome-like radiopaque foci at this early agehas made it a rare entity.

  1. Artefacts in Cone Beam CT Mimicking an Extrapalatal Canal of Root-Filled Maxillary Molar.

    Camilo, Carla Cristina; Brito-Júnior, Manoel; Faria-E-Silva, André Luis; Quintino, Alex Carvalho; de Paula, Adrianne Freire; Cruz-Filho, Antônio Miranda; Sousa-Neto, Manoel Damião

    2013-01-01

    Despite the advantages of cone-beam computed tomography (CBCT), the images provided by this diagnostic tool can produce artifacts and compromise accurate diagnostic assessment. This paper describes an endodontic treatment of a maxillary molar where CBCT images suggested the presence of a nonexistent third root canal in the palatal root. An endodontic treatment was performed in a first maxillary molar with palatal canals, and the tooth was restored with a cast metal crown. The patient returned four years later presenting with a discomfort in chewing, which was reduced after occlusal adjustment. CBCT was prescribed to verify additional diagnostic information. Axial scans on coronal, middle, and apical palatal root sections showed images similar to a third root canal. However, sagittal scans demonstrated that these images were artifacts caused by root canal fillings. A careful interpretation of CBCT images in root-filled teeth must be done to avoid mistakes in treatment.

  2. Anatomical Variation of the Maxillary Sinus in Cone Beam Computed Tomography

    Marcelo Lupion Poleti

    2014-01-01

    Full Text Available Purpose. The aim of this paper is to report a case in which the cone beam computed tomography (CBCT was important for the confirmation of the presence of maxillary sinus septum and, therefore, the absence of a suspected pathologic process. Case Description. A 27-year-old male patient was referred for the assessment of a panoramic radiograph displaying a radiolucent area with radiopaque border located in the apical region of the left upper premolars. The provisional diagnosis was either anatomical variation of the maxillary sinuses or a bony lesion. Conclusion. The CBCT was important for an accurate assessment and further confirmation of the presence of maxillary septum, avoiding unnecessary surgical explorations.

  3. Geometric Parameters Estimation and Calibration in Cone-Beam Micro-CT

    Jintao Zhao

    2015-09-01

    Full Text Available The quality of Computed Tomography (CT images crucially depends on the precise knowledge of the scanner geometry. Therefore, it is necessary to estimate and calibrate the misalignments before image acquisition. In this paper, a Two-Piece-Ball (TPB phantom is used to estimate a set of parameters that describe the geometry of a cone-beam CT system. Only multiple projections of the TPB phantom at one position are required, which can avoid the rotation errors when acquiring multi-angle projections. Also, a corresponding algorithm is derived. The performance of the method is evaluated through simulation and experimental data. The results demonstrated that the proposed method is valid and easy to implement. Furthermore, the experimental results from the Micro-CT system demonstrate the ability to reduce artifacts and improve image quality through geometric parameter calibration.

  4. Scattering correction based on regularization de-convolution for Cone-Beam CT

    Xie, Shi-peng

    2016-01-01

    In Cone-Beam CT (CBCT) imaging systems, the scattering phenomenon has a significant impact on the reconstructed image and is a long-lasting research topic on CBCT. In this paper, we propose a simple, novel and fast approach for mitigating scatter artifacts and increasing the image contrast in CBCT, belonging to the category of convolution-based method in which the projected data is de-convolved with a convolution kernel. A key step in this method is how to determine the convolution kernel. Compared with existing methods, the estimation of convolution kernel is based on bi-l1-l2-norm regularization imposed on both the intermediate the known scatter contaminated projection images and the convolution kernel. Our approach can reduce the scatter artifacts from 12.930 to 2.133.

  5. Cone Beam Computed Tomography Findings in Calcifying Cystic Odontogenic Tumor Associated with Odontome: A Case Report

    Tushar Phulambrikar

    2015-12-01

    Full Text Available The calcifying cystic odontogenic tumor (CCOT is a rare cystic odontogenic neoplasm frequently found in association with odontome. This report documents a case of CCOT associated with an odontome arising in the anterior maxilla in a 28-year-old man. Conventional radiographs showed internal calcification within the lesion but were unable to visualize its relation with the adjacent structures and its accurate extent. In this case cone beam computed tomography (CBCT could accurately reveal the extent and the internal structure of the lesion which aided the presumptive diagnosis of the lesion as CCOT. This advanced imaging technique proved to be extremely useful in the radiographic assessment and management of this neoplasm of the maxilla.

  6. Evaluation of canalis basilaris medianus using cone-beam computed tomography

    Syed, Ali Z.; Zahedpasha, Samir [Dept. of Oral and Maxillofacial Medicine and Diagnostic Sciences, CWRU School of Dental Medicine, Cleveland (United States); Rathore, Sonali A. [Dept. of Oral Diagnostic Sciences, VCU School of Dentistry, Richmond (United States); Mupparapu, Mel [Dept. of Radiology, University of Pennsylvania School of Dental Medicine, Philadelphia (United States)

    2016-06-15

    The aim of this report is to present two cases of canalis basilaris medianus as identified on cone-beam computed tomography (CBCT) in the base of the skull. The CBCT data sets were sent for radiographic consultation. In both cases, multi-planar views revealed an osseous defect in the base of the skull in the clivus region, the sagittal view showed a unilateral, well-defined, non-corticated, track-like low-attenuation osseous defect in the clivus. The appearance of the defect was highly reminiscent of a fracture of the clivus. The borders of osseous defect were smooth, and no other radiographic signs suggestive of osteolytic destructive processes were noted. Based on the overall radiographic examination, a radiographic impression of canalis basilaris medianus was made. Canalis basilaris medianus is a rare anatomical variant and is generally observed on the clivus. Due to its potential association with meningitis, it should be recognized and reported to avoid potential complications.

  7. Accessory mental foramen: A rare anatomical variation detected by cone-beam computed tomography

    Torres, Marianna Guanaes Gomes; De Faro Valverde, Ludmila; Vidal, Manuela Torres Andion; Crusoe-Rebello, Ieda Margarida [Dept. of Oral Radiology, School of Dentistry, Federal University of Bahia, Salvador (Brazil)

    2015-03-15

    The mental foramen is a bilateral opening in the vestibular portion of the mandible through which nerve endings, such as the mental nerve, emerge. In general, the mental foramen is located between the lower premolars. This region is a common area for the placement of dental implants. It is very important to identify anatomical variations in presurgical imaging exams since damage to neurovascular bundles may have a direct influence on treatment success. In the hemimandible, the mental foramen normally appears as a single structure, but there are some rare reports on the presence and number of anatomical variations; these variations may include accessory foramina. The present report describes the presence of accessory mental foramina in the right mandible, as detected by cone-beam computed tomography before dental implant placement.

  8. Fast Scatter Artifacts Correction for Cone-Beam CT without System Modification and Repeat Scan

    Zhao, Wei; Wang, Luyao

    2015-01-01

    We provide a fast and accurate scatter artifacts correction algorithm for cone beam CT (CBCT) imaging. The method starts with an estimation of coarse scatter profile for a set of CBCT images. A total-variation denoising algorithm designed specifically for Poisson signal is then applied to derive the final scatter distribution. Qualitatively and quantitatively evaluations using Monte Carlo (MC) simulations, experimental CBCT phantom data, and \\emph{in vivo} human data acquired for a clinical image guided radiation therapy were performed. Results show that the proposed algorithm can significantly reduce scatter artifacts and recover the correct HU within either projection domain or image domain. Further test shows the method is robust with respect to segmentation procedure.

  9. Accuracy of linear measurements from cone-beam computed tomography-derived surface models of different voxel sizes

    Damstra, Janalt; Fourie, Zacharias; Huddleston Slater, James J R; Ren, Yijin

    2010-01-01

    INTRODUCTION: The aims of this study were to determine the linear accuracy of 3-dimensional surface models derived from a commercially available cone-beam computed tomography (CBCT) dental imaging system and volumetric rendering software and to investigate the influence of voxel resolution on the li

  10. Impacted maxillary canines and root resorptions of neighbouring teeth: a radiographic analysis using cone-beam computed tomography

    Lai, C.S.; Bornstein, M.M.; Mock, L.; Heuberger, B.M.; Dietrich, T.; Katsaros, C.

    2013-01-01

    The study analyses the location of impacted maxillary canines and factors influencing root resorptions of adjacent teeth using cone-beam computed tomography (CBCT). In addition, the interrater reliability between observers of two different dental specialties for radiographic parameters will be evalu

  11. Guided access cavity preparation using cone-beam computed tomography and optical surface scans - an ex vivo study

    Buchgreitz, J; Buchgreitz, M; Mortensen, D

    2016-01-01

    AIM: To evaluate ex vivo, the accuracy of a preparation procedure planned for teeth with pulp canal obliteration (PCO) using a guide rail concept based on a cone-beam computed tomography (CBCT) scan merged with an optical surface scan. METHODOLOGY: A total of 48 teeth were mounted in acrylic bloc...

  12. A dual centre study of setup accuracy for thoracic patients based on Cone-Beam CT data

    Nielsen, Tine B; Hansen, Vibeke N; Westberg, Jonas;

    2011-01-01

    BACKGROUND AND PURPOSE: To compare setup uncertainties at two different institutions by using identical imaging and analysis techniques for thoracic patients with different fixation equipments. METHODS AND MATERIALS: Patient registration results from Cone-Beam CT (CBCT) scans of 174 patients were...

  13. Radiologic evaluation of an unusually sized complex odontoma involving the maxillary sinus by cone beam computed tomography.

    Isler, Sabri Cemil; Demircan, Sabit; Soluk, Merva; Cebi, Zerrin

    2009-01-01

    As a group, odontomas are the most common odontogenic neoplasms. This case report illustrates the benefits of cone beam computed tomography, in terms of treatment planning and surgical technique, to localize a large maxillary odontoma and accurately establish its relationship with the maxillary sinus and molar.

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

    Vos, W. De; Casselman, J.W.; Swennen, G.R.

    2009-01-01

    This study reviewed the literature on cone-beam computerized tomography (CBCT) imaging of the oral and maxillofacial (OMF) region. A PUBMED search (National Library of Medicine, NCBI; revised 1 December 2007) from 1998 to December 2007 was conducted. This search revealed 375 papers, which were scree

  15. Cone-beam computerized tomography imaging and analysis of the upper airway: a systematic review of the literature.

    Guijarro-Martinez, R.; Swennen, G.R.J.

    2011-01-01

    A systematic review of the literature concerning upper airway imaging and analysis using cone-beam computed tomography (CBCT) was performed. A PubMed search (National Library of Medicine, NCBI; revised 9th January 2011) yielded 382 papers published between 1968 and 2010. The 382 full papers were scr

  16. Outcome of root canal treatment in dogs determined by periapical radiography and cone-beam computed tomography scans

    de Paula-Silva, F.W.G.; Hassan, B.; da Silva, L.A.B.; Leonardo, M.R.; Wu, M.K.

    2009-01-01

    The purpose of this study was to compare the favorable outcome of root canal treatment determined by periapical radiographs (PRs) and cone beam computed tomography (CBCT) scans. Ninety-six roots of dogs' teeth were used to form four groups (n= 24). In group 1, root canal treatments were performed in

  17. Clinical relevance of cone beam computed tomography in mandibular third molar removal: A multicentre, randomised, controlled trial

    Ghaeminia, H.; Gerlach, N.L.; Hoppenreijs, T.J.; Kicken, M.; Dings, J.P.; Borstlap, W.A.; Haan, T. de; Berge, S.J.; Meijer, G.J.; Maal, T.J.J.

    2015-01-01

    PURPOSE: The aims of this study were to investigate the effectiveness of cone beam computed tomography (CBCT) compared to panoramic radiography (PR), prior to mandibular third molar removal, in reducing patient morbidity, and to identify risk factors associated with inferior alveolar nerve (IAN) inj

  18. Influence of object location in different FOVs on trabecular bone microstructure measurements of human mandible: a cone beam CT study

    Ibrahim, N.; Parsa, A.; Hassan, B.; van der Stelt, P.; Aartman, I.H.A.; Nambiar, P.

    2014-01-01

    The aim of this study was to assess the influence of different object locations in different fields of view (FOVs) of two cone beam CT (CBCT) systems on trabecular bone microstructure measurements of a human mandible. A block of dry human mandible was scanned at five different locations (centre, lef

  19. Comparison of in vivo cone-beam and multidetector computed tomographic scans by three-dimensional merging software.

    Rostetter, Claudio; Metzler, Philipp; Schenkel, Jan S; Seifert, Burkhardt; Luebbers, Heinz-Theo

    2015-12-01

    In dentomaxillofacial radiology, cone-beam computed tomography (CT) is used to give fast and high-resolution 3-dimensional images of bone with a low dose of radiation. However, its use for quantitative measurement of bone density based on absolute values (Hounsfield units, HU) as in multidetector CT is still controversial. We know of no in vivo study of 3-dimensional merging software that will reliably match identical bone areas of cone-beam and multidetector CT datasets. We studied 19 multidetector, and 19 cone-beam, CT scans of the skull. The two datasets were fused, corresponding points were identified for measurement, and we compared mean density. We used linear regression to analyse the relation between the two different scanning methods, and studied a total of 4180 measurements. The mean time interval between scans was 5.2 (4.7) months. Mean R(2) over all measurements was 0.63 (range 0.22 - 0.79) with a mean internal consistency (Cronbach's α) of 0.86 (range 0.61 - 0.93). The strongest linearity, seen at the left mastoid, was R(2)=0.79 with high internal consistency (Cronbach's α 0.89), and the weakest was at the left zygomatic bone with R(2)=0.22 and Cronbach's α=0.61. Measurements of bone density based on cone-beam and multidetector CT scans generated in vivo showed high and reproducible internal consistency but poor linearity.

  20. Cone beam computed tomography guided treatment delivery and planning verification for magnetic resonance imaging only radiotherapy of the brain

    Edmund, Jens M.; Andreasen, Daniel; Mahmood, Faisal;

    2015-01-01

    Background. Radiotherapy based on MRI only (MRI-only RT) shows a promising potential for the brain. Much research focuses on creating a pseudo computed tomography (pCT) from MRI for treatment planning while little attention is often paid to the treatment delivery. Here, we investigate if cone beam...

  1. Optimizing cone beam CT scatter estimation in egs_cbct for a clinical and virtual chest phantom

    Slot Thing, Rune; Mainegra-Hing, Ernesto

    2014-01-01

    PURPOSE: Cone beam computed tomography (CBCT) image quality suffers from contamination from scattered photons in the projection images. Monte Carlo simulations are a powerful tool to investigate the properties of scattered photons.egs_cbct, a recent EGSnrc user code, provides the ability...

  2. Radiation dose response of normal lung assessed by Cone Beam CT - a potential tool for biologically adaptive radiation therapy

    Bertelsen, Anders; Schytte, Tine; Bentzen, Søren M;

    2011-01-01

    Density changes of healthy lung tissue during radiotherapy as observed by Cone Beam CT (CBCT) might be an early indicator of patient specific lung toxicity. This study investigates the time course of CBCT density changes and tests for a possible correlation with locally delivered dose....

  3. Value of cone-beam computed tomography in the process of diagnosis and management of disorders of the temporomandibular joint

    de Boer, E. W. J.; Dijkstra, P. U.; Stegenga, B.; de Bont, L. G. M.; Spijkervet, F. K. L.

    2014-01-01

    The objective of this study was to assess the value of cone-beam computed tomographic (CT) images in the primary diagnosis and management of 128 outpatients with disorders of the temporomandibular joint (TMJ). Before a diagnosis was made and treatment planned, the history was taken, physical examina

  4. Assessment of bone segmentation quality of cone-beam CT versus multislice spiral CT: a pilot study.

    Loubele, M.; Maes, F.; Schutyser, F.A.C.; Marchal, G.; Jacobs, R.; Suetens, P.

    2006-01-01

    OBJECTIVES: The objective of this study was to quantitatively assess the quality of jawbone models generated from cone beam computed tomography (CBCT) by comparison with similar models obtained from multislice spiral computed tomography (MSCT). MATERIAL AND METHODS: Three case studies were performed

  5. High-dose-rate prostate brachytherapy based on registered transrectal ultrasound and in-room cone-beam CT images

    Even, Aniek J.G.; Nuver, Tonnis T.; Westendorp, Hendrik; Hoekstra, Carel J.; Slump, C.H.; Minken, Andre W.

    2014-01-01

    Purpose To present a high-dose-rate (HDR) brachytherapy procedure for prostate cancer using transrectal ultrasound (TRUS) to contour the regions of interest and registered in-room cone-beam CT (CBCT) images for needle reconstruction. To characterize the registration uncertainties between the two ima

  6. Generation of a cold pulsed beam of Rb atoms by transfer from a 3D magneto-optic trap

    Chanu, Sapam Ranjita; Natarajan, Vasant

    2016-01-01

    We demonstrate a technique for producing a cold pulsed beam of atoms by transferring a cloud of atoms trapped in a three dimensional magneto-optic trap (MOT). The MOT is loaded by heating a getter source of Rb atoms. We show that it is advantageous to transfer with two beams (with a small angle between them) compared to a single beam, because the atoms stop interacting with the beams in the two-beam technique, which results in a Gaussian velocity distribution. The atoms are further cooled in optical molasses by turning off the MOT magnetic field before the transfer beams are turned on.

  7. In-treatment 4D cone-beam CT with image-based respiratory phase recognition.

    Kida, Satoshi; Masutani, Yoshitaka; Yamashita, Hideomi; Imae, Toshikazu; Matsuura, Taeko; Saotome, Naoya; Ohtomo, Kuni; Nakagawa, Keiichi; Haga, Akihiro

    2012-07-01

    The use of respiration-correlated cone-beam computed tomography (4D-CBCT) appears to be crucial for implementing precise radiation therapy of lung cancer patients. The reconstruction of 4D-CBCT images requires a respiratory phase. In this paper, we propose a novel method based on an image-based phase recognition technique using normalized cross correlation (NCC). We constructed the respiratory phase by searching for a region in an adjacent projection that achieves the maximum correlation with a region in a reference projection along the cranio-caudal direction. The data on 12 lung cancer patients acquired just prior to treatment and on 3 lung cancer patients acquired during volumetric modulated arc therapy treatment were analyzed in the search for the effective area of cone-beam projection images for performing NCC with 12 combinations of registration area and segment size. The evaluation was done by a "recognition rate" defined as the ratio of the number of peak inhales detected with our method to that detected by eye (manual tracking). The average recognition rate of peak inhale with the most efficient area in the present method was 96.4%. The present method was feasible even when the diaphragm was outside the field of view. With the most efficient area, we reconstructed in-treatment 4D-CBCT by dividing the breathing signal into four phase bins; peak exhale, peak inhale, and two intermediate phases. With in-treatment 4D-CBCT images, it was possible to identify the tumor position and the tumor size in moments of inspiration and expiration, in contrast to in-treatment CBCT reconstructed with all projections.

  8. SU-E-J-43: Deformed Planning CT as An Electron Density Substitute for Cone-Beam CT

    Mishra, K [Cleveland State University, Cleveland, OH (United States); Godley, A [Cleveland Clinic, Cleveland, OH (United States)

    2014-06-01

    Purpose: To confirm that deforming the planning CT to the daily Cone-Beam CTs (CBCT) can provide suitable electron density for adaptive planning. We quantify the dosimetric difference between plans calculated on deformed planning CTs (DPCT) and daily CT-on-rails images (CTOR). CTOR is used as a test of the method as CTOR already contains accurate electron density to compare against. Methods: Five prostate only IMRT patients, each with five CTOR images, were selected and re-planned on Panther (Prowess Inc.) with a uniform 5 mm PTV expansion, prescribed 78 Gy. The planning CT was deformed to match each CTOR using ABAS (Elekta Inc.). Contours were drawn on the CTOR, and copied to the DPCT. The original treatment plan was copied to both the CTOR and DPCT, keeping the center of the prostate as the isocenter. The plans were then calculated using the collapsed cone heterogeneous dose engine of Prowess and typical DVH planning parameters used to compare them. Results: Each DPCT was visually compared to its CTOR with no differences observed. The agreement of the copied CTOR contours with the DPCT anatomy further demonstrated the deformation accuracy. The plans calculated using CTOR and DPCT were compared. Over the 25 plan pairs, the average difference between them for prostate D100, D98 and D95 were 0.5%, 0.2%, and 0.2%; PTV D98, D95 and mean dose: 0.3%, 0.2% and 0.3%; bladder V70, V60 and mean dose: 1.1%, 0.7%, and 0.2%; and rectum mean dose: 0.3%. (D100 is the dose covering 100% of the target; V70 is the volume of the organ receiving 70 Gy). Conclusion: We observe negligible difference between the dose calculated on the DPCT and the CTOR, implying that deformed planning CTs are a suitable substitute for electron density. The method can now be applied to CBCTs. Research version of Panther provided by Prowess Inc. Research version of ABAS provided by Elekta Inc.

  9. Commissioning and validation of BrainLAB cones for 6X FFF and 10X FFF beams on a Varian TrueBeam STx.

    Wiant, David B; Terrell, Jonathon A; Maurer, Jacqueline M; Yount, Caroline L; Sintay, Benjamin J

    2013-11-04

    Small field dosimetry is a challenging task. The difficulties of small field measurements, particularly stereotactic field size measurements, are highlighted by the large interinstitution variability that can be observed for circular cone collimator commissioning measurements. We believe the best way to improve the consistency of small field measurements is to clearly document and share the results of small field measurements. In this work we report on the commissioning and validation of a BrainLAB cone system for 6 MV and 10 MV flattening filter-free (FFF) beams on a Varian TrueBeam STx. Commissioning measurements consisted of output factors, percent depth dose, and off-axis factor measurements with a diode. Validation measurements were made in a polystyrene slab phantom at depths of 5 cm, 10 cm, and 15 cm using radiochromic film. Output factors for the 6xFFF cones are 0.689, 0.790, 0.830, 0.871, 0.890, and 0.901 for 4 mm, 6 mm, 7.5 mm, 10 mm, 12.5 mm, and the 15 mm cones, respectively. Output factors for the 10xFFF cones are 0.566, 0.699, 0.756, 0.826, 0.864, and 0.888 for 4 mm, 6 mm, 7.5 mm, 10 mm, 12.5 mm, and the 15 mm cones, respectively. The full width half maximum values of the off-axis factors agreed with the nominal cone size to within 0.5 mm. Validation measurements showed an agreement of absolute dose between calculation and plan of < 3.6%, and an agreement of field sizes of ≤ 0.3 mm in all cases. Radiochromic film validation measurements show reasonable agreement with beam models for circular collimators based on diode commissioning measurements.

  10. Visualizing the 3D Architecture of Multiple Erythrocytes Infected with Plasmodium at Nanoscale by Focused Ion Beam-Scanning Electron Microscopy

    Soares Medeiros, Lia Carolina; De Souza, Wanderley; Jiao, Chengge; Barrabin, Hector; Miranda, Kildare

    2012-01-01

    Different methods for three-dimensional visualization of biological structures have been developed and extensively applied by different research groups. In the field of electron microscopy, a new technique that has emerged is the use of a focused ion beam and scanning electron microscopy for 3D reconstruction at nanoscale resolution. The higher extent of volume that can be reconstructed with this instrument represent one of the main benefits of this technique, which can provide statistically relevant 3D morphometrical data. As the life cycle of Plasmodium species is a process that involves several structurally complex developmental stages that are responsible for a series of modifications in the erythrocyte surface and cytoplasm, a high number of features within the parasites and the host cells has to be sampled for the correct interpretation of their 3D organization. Here, we used FIB-SEM to visualize the 3D architecture of multiple erythrocytes infected with Plasmodium chabaudi and analyzed their morphometrical parameters in a 3D space. We analyzed and quantified alterations on the host cells, such as the variety of shapes and sizes of their membrane profiles and parasite internal structures such as a polymorphic organization of hemoglobin-filled tubules. The results show the complex 3D organization of Plasmodium and infected erythrocyte, and demonstrate the contribution of FIB-SEM for the obtainment of statistical data for an accurate interpretation of complex biological structures. PMID:22432024

  11. WE-D-9A-02: Automated Landmark-Guided CT to Cone-Beam CT Deformable Image Registration

    Kearney, V; Gu, X; Chen, S; Jiang, L; Liu, H; Chiu, T; Yordy, J; Nedzi, L; Mao, W [UT Southwestern Medical Center, Dallas, TX (United States)

    2014-06-15

    Purpose: The anatomical changes that occur between the simulation CT and daily cone-beam CT (CBCT) are investigated using an automated landmark-guided deformable image registration (LDIR) algorithm with simultaneous intensity correction. LDIR was designed to be accurate in the presence of tissue intensity mismatch and heavy noise contamination. Method: An auto-landmark generation algorithm was used in conjunction with a local small volume (LSV) gradient matching search engine to map corresponding landmarks between the CBCT and planning CT. The LSVs offsets were used to perform an initial deformation, generate landmarks, and correct local intensity mismatch. The landmarks act as stabilizing controlpoints in the Demons objective function. The accuracy of the LDIR algorithm was evaluated on one synthetic case with ground truth and data of ten head and neck cancer patients. The deformation vector field (DVF) accuracy was accessed using a synthetic case. The Root mean square error of the 3D canny edge (RMSECE), mutual information (MI), and feature similarity index metric (FSIM) were used to access the accuracy of LDIR on the patient data. The quality of the corresponding deformed contours was verified by an attending physician. Results: The resulting 90 percentile DVF error for the synthetic case was within 5.63mm for the original demons algorithm, 2.84mm for intensity correction alone, 2.45mm using controlpoints without intensity correction, and 1.48 mm for the LDIR algorithm. For the five patients the mean RMSECE of the original CT, Demons deformed CT, intensity corrected Demons CT, control-point stabilized deformed CT, and LDIR CT was 0.24, 0.26, 0.20, 0.20, and 0.16 respectively. Conclusion: LDIR is accurate in the presence of multimodal intensity mismatch and CBCT noise contamination. Since LDIR is GPU based it can be implemented with minimal additional strain on clinical resources. This project has been supported by a CPRIT individual investigator award RP11032.

  12. Daily cone-beam computed tomography used to determine tumour shrinkage and localisation in lung cancer patients

    Marquard Knap, Marianne; Nordsmark, Marianne (Aarhus Univ. Hospital, Dept. of Oncology, Aarhus (Denmark)), E-mail: mariknap@rm.dk; Hoffmann, Lone; Vestergaard, Anne (Aarhus Univ. Hospital, Dept. of Medical Physics, Aarhus (Denmark))

    2010-10-15

    Purpose/Objective. Daily Cone-beam computed tomography (CBCT) in room imaging is used to determine tumour shrinkage during a full radiotherapy (RT) course. In addition, relative interfractional tumour and lymph node motion is determined for each RT fraction. Material and methods. From November 2009 to March 2010, 20 consecutive lung cancer patients (14 NSCLC, 6 SCLC) were followed with daily CBCT during RT. The gross tumour volume for lung tumour (GTV-t) was visible in all daily CBCT scans and was delineated at the beginning, at the tenth and the 20th fraction, and at the end of treatment. Whenever visible, the gross tumour volume for lymph nodes (GTV-n) was also delineated. The GTV-t and GTV-n volumes were determined. All patients were setup according to an online bony anatomy match. Retrospectively, matching based on the internal target volume (ITV), the GTV-t or the GTV-n was performed. Results. In eight patients, we observed a significant GTV-t shrinkage (15-40%) from the planning CT until the last CBCT. Only five patients presented a significant shrinkage (21-37%) in the GTV-n. Using the daily CBCT imaging, it was found that the mean value of the difference between a setup using the skin tattoo and an online matching using the ITV was 7.3+-2.9 mm (3D vector in the direction of ITV). The mean difference between the ITV and bony anatomy matching was 3.0+-1.3 mm. Finally, the mean distance between the GTV-t and the GTV-N was 2.9+-1.6 mm. Conclusion. One third of all patients with lung cancer undergoing chemo-RT achieved significant tumour shrinkage from planning CT until the end of the radiotherapy. Differences in GTV-t and GTV-n motion was observed and matching using the ITV including both GTV-t and GTV-n is therefore preferable.

  13. 4D cone-beam CT imaging for guidance in radiation therapy: setup verification by use of implanted fiducial markers

    Jin, Peng; van Wieringen, Niek; Hulshof, Maarten C. C. M.; Bel, Arjan; Alderliesten, Tanja

    2016-03-01

    The use of 4D cone-beam computed tomography (CBCT) and fiducial markers for guidance during radiation therapy of mobile tumors is challenging due to the trade-off between image quality, imaging dose, and scanning time. We aimed to investigate the visibility of markers and the feasibility of marker-based 4D registration and manual respiration-induced marker motion quantification for different CBCT acquisition settings. A dynamic thorax phantom and a patient with implanted gold markers were included. For both the phantom and patient, the peak-to-peak amplitude of marker motion in the cranial-caudal direction ranged from 5.3 to 14.0 mm, which did not affect the marker visibility and the associated marker-based registration feasibility. While using a medium field of view (FOV) and the same total imaging dose as is applied for 3D CBCT scanning in our clinic, it was feasible to attain an improved marker visibility by reducing the imaging dose per projection and increasing the number of projection images. For a small FOV with a shorter rotation arc but similar total imaging dose, streak artifacts were reduced due to using a smaller sampling angle. Additionally, the use of a small FOV allowed reducing total imaging dose and scanning time (~2.5 min) without losing the marker visibility. In conclusion, by using 4D CBCT with identical or lower imaging dose and a reduced gantry speed, it is feasible to attain sufficient marker visibility for marker-based 4D setup verification. Moreover, regardless of the settings, manual marker motion quantification can achieve a high accuracy with the error <1.2 mm.

  14. Frequency Distribution of Edentulous Posterior Mandibular Ridge Types using Cone Beam Computed Tomography in an Iranian Population

    2016-07-01

    Full Text Available Introduction: The existing bone is regarded as an important criteria in dental implants. In this regard, the radiographic modality is of great significance in quantifying the remaining bone, and CBCT accurately represents height and width of the existing bone. Therefore, this study aimed to evaluate the frequency distribution of the edentulous posterior mandibular ridge types using cone beam computed tomography in an Iranian population. Methods: In this cross-sectional descriptive study, CBCT scans of 127 patients with full edentulous mandible with an average age of 61.15 were evaluated who referred to a radiology clinic in Tehran. The images were analyzed applying OnDemand3D application and bone height and width of each area were determined. To analyze the collected data, SPSS software (ver,17 was employed applying Fisher's exact test. Results: The ridges were classified in 4 different groups (A,B+,B-w,C-w. The frequency of ridge types A and B + in male and ridge types B-w and C-w in females were demonstrated to be higher. An increase in age led to a reduction in the frequency of type A and a rise in the frequency of type C-w. The mean bone height was higher in males in all areas. In addition, the mean bone width was higher in males in all areas except for the first molar area. Conclusions:  The study results indicated that as the age increases, the height of edentulous mandible reduces, while no significant relationship was detected between the bone width and aging. As a result, with aging the evolution of bone was held to be from type A to type C-W.

  15. Percutaneous Bone Biopsies: Comparison between Flat-Panel Cone-Beam CT and CT-Scan Guidance

    Tselikas, Lambros, E-mail: lambros.tselikas@gmail.com; Joskin, Julien, E-mail: j.joskin@gmail.com [Gustave Roussy, Interventional Radiology Department (France); Roquet, Florian, E-mail: florianroquet@hotmail.com [Gustave Roussy, Biostatistics Department (France); Farouil, Geoffroy, E-mail: g.farouil@gmail.com [Gustave Roussy, Interventional Radiology Department (France); Dreuil, Serge, E-mail: serge.dreuil@gustaveroussy.fr [Gustave Roussy, Medical Physics Department (France); Hakimé, Antoine, E-mail: thakime@yahoo.com; Teriitehau, Christophe, E-mail: cteriitehau@me.com [Gustave Roussy, Interventional Radiology Department (France); Auperin, Anne, E-mail: anne.auperin@gustaveroussy.fr [Gustave Roussy, Biostatistics Department (France); Baere, Thierry de, E-mail: thierry.debaere@gustaveroussy.fr; Deschamps, Frederic, E-mail: frederic.deschamps@gustaveroussy.fr [Gustave Roussy, Interventional Radiology Department (France)

    2015-02-15

    PurposeThis study was designed to compare the accuracy of targeting and the radiation dose of bone biopsies performed either under fluoroscopic guidance using a cone-beam CT with real-time 3D image fusion software (FP-CBCT-guidance) or under conventional computed tomography guidance (CT-guidance).MethodsSixty-eight consecutive patients with a bone lesion were prospectively included. The bone biopsies were scheduled under FP-CBCT-guidance or under CT-guidance according to operating room availability. Thirty-four patients underwent a bone biopsy under FP-CBCT and 34 under CT-guidance. We prospectively compared the two guidance modalities for their technical success, accuracy, puncture time, and pathological success rate. Patient and physician radiation doses also were compared.ResultsAll biopsies were technically successful, with both guidance modalities. Accuracy was significantly better using FP-CBCT-guidance (3 and 5 mm respectively: p = 0.003). There was no significant difference in puncture time (32 and 31 min respectively, p = 0.51) nor in pathological results (88 and 88 % of pathological success respectively, p = 1). Patient radiation doses were significantly lower with FP-CBCT (45 vs. 136 mSv, p < 0.0001). The percentage of operators who received a dose higher than 0.001 mSv (dosimeter detection dose threshold) was lower with FP-CBCT than CT-guidance (27 vs. 59 %, p = 0.01).ConclusionsFP-CBCT-guidance for bone biopsy is accurate and reduces patient and operator radiation doses compared with CT-guidance.

  16. Volumetric Modulation Arc Radiotherapy With Flattening Filter-Free Beams Compared With Static Gantry IMRT and 3D Conformal Radiotherapy for Advanced Esophageal Cancer: A Feasibility Study

    Nicolini, Giorgia, E-mail: giorgia.nicolini@eoc.ch [Oncology Institute of Southern Switzerland, Medical Physics Unit, Bellinzona (Switzerland); Ghosh-Laskar, Sarbani; Shrivastava, Shyam Kishore; Banerjee, Sushovan; Chaudhary, Suresh; Agarwal, Jai Prakash; Munshi, Anusheel [Tata Memorial Hospital, Mumbai (India); Clivio, Alessandro; Fogliata, Antonella [Oncology Institute of Southern Switzerland, Medical Physics Unit, Bellinzona (Switzerland); Mancosu, Pietro [Department of Radiation Oncology, Istituto Clinico Humanitas, Milano-Rozzano (Italy); Vanetti, Eugenio; Cozzi, Luca [Oncology Institute of Southern Switzerland, Medical Physics Unit, Bellinzona (Switzerland)

    2012-10-01

    Purpose: A feasibility study was performed to evaluate RapidArc (RA), and the potential benefit of flattening filter-free beams, on advanced esophageal cancer against intensity-modulated radiotherapy (IMRT) and three-dimensional conformal radiotherapy (3D-CRT). Methods and Materials: The plans for 3D-CRT and IMRT with three to seven and five to seven fixed beams were compared against double-modulated arcs with avoidance sectors to spare the lungs for 10 patients. All plans were optimized for 6-MV photon beams. The RA plans were studied for conventional and flattening filter-free (FFF) beams. The objectives for the planning target volume were the volume receiving {>=}95% or at most 107% of the prescribed dose of <1% with a dose prescription of 59.4 Gy. For the organs at risk, the lung volume (minus the planning target volume) receiving {>=}5 Gy was <60%, that receiving 20 Gy was <20%-30%, and the mean lung dose was <15.0 Gy. The heart volume receiving 45 Gy was <20%, volume receiving 30 Gy was <50%. The spinal dose received by 1% was <45 Gy. The technical delivery parameters for RA were assessed to compare the normal and FFF beam characteristics. Results: RA and IMRT provided equivalent coverage and homogeneity, slightly superior to 3D-CRT. The conformity index was 1.2 {+-} 0.1 for RA and IMRT and 1.5 {+-} 0.2 for 3D-CRT. The mean lung dose was 12.2 {+-} 4.5 for IMRT, 11.3 {+-} 4.6 for RA, and 10.8 {+-} 4.4 for RA with FFF beams, 18.2 {+-} 8.5 for 3D-CRT. The percentage of volume receiving {>=}20 Gy ranged from 23.6% {+-} 9.1% to 21.1% {+-} 9.7% for IMRT and RA (FFF beams) and 39.2% {+-} 17.0% for 3D-CRT. The heart and spine objectives were met by all techniques. The monitor units for IMRT and RA were 457 {+-} 139, 322 {+-} 20, and 387 {+-} 40, respectively. RA with FFF beams showed, compared with RA with normal beams, a {approx}20% increase in monitor units per Gray, a 90% increase in the average dose rate, and 20% reduction in beam on time (owing to different

  17. A One-Step Cone-Beam CT-Enabled Planning-to-Treatment Model for Palliative Radiotherapy-From Development to Implementation

    Wong, Rebecca K.S., E-mail: rebecca.wong@rmp.uhn.on.ca [Radiation Medicine Program, Princess Margaret Hospital, Toronto, Ontario (Canada); Department of Radiation Oncology, University of Toronto, Toronto, Ontario (Canada); Letourneau, Daniel; Varma, Anita [Radiation Medicine Program, Princess Margaret Hospital, Toronto, Ontario (Canada); Department of Radiation Oncology, University of Toronto, Toronto, Ontario (Canada); Bissonnette, Jean Pierre; Fitzpatrick, David; Grabarz, Daniel; Elder, Christine [Radiation Medicine Program, Princess Margaret Hospital, Toronto, Ontario (Canada); Martin, Melanie; Bezjak, Andrea [Radiation Medicine Program, Princess Margaret Hospital, Toronto, Ontario (Canada); Department of Radiation Oncology, University of Toronto, Toronto, Ontario (Canada); Panzarella, Tony [Department of Biostatistics, Princess Margaret Hospital, Toronto, Ontario (Canada); Gospodarowicz, Mary [Radiation Medicine Program, Princess Margaret Hospital, Toronto, Ontario (Canada); Department of Radiation Oncology, University of Toronto, Toronto, Ontario (Canada); Jaffray, David A. [Radiation Medicine Program, Princess Margaret Hospital, Toronto, Ontario (Canada); Department of Radiation Oncology, University of Toronto, Toronto, Ontario (Canada); Department of Medical Biophysics, University of Toronto, Toronto, Ontario (Canada)

    2012-11-01

    Purpose: To develop a cone-beam computed tomography (CT)-enabled one-step simulation-to-treatment process for the treatment of bone metastases. Methods and Materials: A three-phase prospective study was conducted. Patients requiring palliative radiotherapy to the spine, mediastinum, or abdomen/pelvis suitable for treatment with simple beam geometry ({<=}2 beams) were accrued. Phase A established the accuracy of cone-beam CT images for the purpose of gross tumor target volume (GTV) definition. Phase B evaluated the feasibility of implementing the cone-beam CT-enabled planning process at the treatment unit. Phase C evaluated the online cone-beam CT-enabled process for the planning and treatment of patients requiring radiotherapy for bone metastases. Results: Eighty-four patients participated in this study. Phase A (n = 9) established the adequacy of cone-beam CT images for target definition. Phase B (n = 45) established the quality of treatment plans to be adequate for clinical implementation for bone metastases. When the process was applied clinically in bone metastases (Phase C), the degree of overlap between planning computed tomography (PCT) and cone-beam CT for GTV and between PCT and cone-beam CT for treatment field was 82% {+-} 11% and 97% {+-} 4%, respectively. The oncologist's decision to accept the plan under a time-pressured environment remained of high quality, with the cone-beam CT-generated treatment plan delivering at least 90% of the prescribed dose to 100% {+-} 0% of the cone-beam CT planning target volume (PTV). With the assumption that the PCT PTV is the gold-standard target, the cone-beam CT-generated treatment plan delivered at least 90% and at least 95% of dose to 98% {+-} 2% and 97% {+-} 5% of the PCT PTV, respectively. The mean time for the online planning and treatment process was 32.7 {+-} 4.0 minutes. Patient satisfaction was high, with a trend for superior satisfaction with the cone-beam CT-enabled process. Conclusions: The cone-beam

  18. Low-dose 2.5 MV cone-beam computed tomography with thick CsI flat-panel imager.

    Tang, Grace; Moussot, Christopher; Morf, Daniel; Seppi, Edward; Amols, Howard

    2016-07-08

    Most of the treatment units, both new and old models, are equipped with a megavoltage portal imager but its use for volumetric imaging is limited. This is mainly due to the poor image quality produced by the high-energy treatment beam (> 6MV). A linac at our center is equipped with a prototype 2.5 MV imaging beam. This study evaluates the feasibility of low-dose megavoltage cone-beam imaging with the 2.5MV beam and a thick cesium iodide detector, which is a high-efficiency imager. Basic imaging properties such as spatial resolution and modulation transfer function were assessed for the 2.5 MV prototype imaging system. For image quality and imaging dose, a series of megavoltage cone-beam scans were acquired for the head, thorax, and pelvis of an anthropomorphic phantom and were compared to kilovoltage cone-beam and 6X megavoltage cone-beam images. To demonstrate the advantage of MV imaging, a phantom with metallic inserts was scanned and the image quality was compared to CT and kilovoltage cone-beam scans. With a lower energy beam and higher detector efficiency, the 2.5 MV imaging system generally yields better image quality than does the 6 MV imaging system with the conventional MV imager. In particular, with the anthropomorphic phantom studies, the contrast to noise of bone to tissue is generally improved in the 2.5 MV images compared to 6 MV. With an image quality sufficient for bony alignment, the imaging dose for 2.5 MV cone-beam images is 2.4-3.4 MU compared to 26 MU in 6 MV cone-beam scans for the head, thorax, and pelvis regions of the phantom. Unlike kilovoltage cone-beam, the 2.5 MV imaging system does not suffer from high-Z image artifacts. This can be very useful for treatment planning in cases where high-Z prostheses are present.

  19. The use of cone beam computed tomography for the assessment of trichorhinophalangeal syndrome, type I – a case report

    Ghoneima, Ahmed; Sachdeva, Kanwar; Hartsfield, James; Weaver, David; Kula, Katherine

    2016-01-01

    Trichorhinophalangeal syndrome type I is a rare autosomal dominant disorder characterized by cone-shaped epiphysis, sparse fine hair, pear-shaped nose and variable growth retardation. The typical craniofacial features include thin upper lip, elongated philtrum, large outstanding ears, shortened posterior facial height associated with short mandibular ramus and reduced and superiorly deflected posterior cranial base. This report describes a 17-year-old male patient with trichorhinophalangeal syndrome type I and a detailed description of the craniofacial radiographic findings, including the use of cone beam computed tomography images for determination of the airway and temporomandibular joint discrepancies. PMID:23524547

  20. 3D PIC simulations of electron beams created via reflection of intense laser light from a water target

    Ngirmang, Gregory K; Feister, Scott; Morrison, John T; Chowdhury, Enam A; Frische, Kyle; Roquemore, W M

    2015-01-01

    We present 3D Particle-in-Cell (PIC) modeling of an ultra-intense laser experiment by the Extreme Light group at the Air Force Research Laboratory (AFRL) using the PIC code LSP. This is the first time PIC simulations have been performed in 3D for this experiment which involves an ultra-intense, short-pulse (30 fs) laser interacting with a water jet target at normal incidence. These 3D PIC simulation results are compared to results from 2D(3$v$) PIC simulations for both $5.4\\cdot10^{17}$ W cm$^{-2}$ and $3\\cdot10^{18}$ W cm$^{-2}$ intensities. Comparing the 2D(3$v$) and 3D simulation results, the laser-energy-to-ejected-electron-energy conversion efficiencies were comparable, but the angular distribution of ejected electrons show interesting differences with qualitative differences at higher intensity. An analytic plane-wave model is provided that provides some explanation for the angular distribution and energies of ejected electrons in the 2D(3$v$) simulations. We also performed a 3D simulation with circular...