Search results for " Computed Tomography"
showing 10 items of 411 documents
Simple computation of the approximated modulation transfer function (MTF) using spreadsheet-software: method and evaluation in five maxillofacial CBC…
2019
OBJECTIVES: To develop a simple way to compute the approximated modulation transfer function (MTF) manually using conventional spreadsheet software. METHODS: Basing on an edge-image a method was developed, facilitating computation of the edge spread and line spread function in open-source spreadsheet software (Gnumeric; http://projects.gnome.org/gnumeric/downloads.shtml). By means of the integrated fast Fourier transformation Fourier coefficients are obtained from the line spread function which can then be plotted vs spatial frequency to obtain MTF-plots. For the experimental evaluation an edge test object was exposed in five commercial CBCT devices for maxillofacial applications. RESULTS: …
Automated detection of lung nodules in low-dose computed tomography
2007
A computer-aided detection (CAD) system for the identification of pulmonary nodules in low-dose multi-detector computed-tomography (CT) images has been developed in the framework of the MAGIC-5 Italian project. One of the main goals of this project is to build a distributed database of lung CT scans in order to enable automated image analysis through a data and cpu GRID infrastructure. The basic modules of our lung-CAD system, consisting in a 3D dot-enhancement filter for nodule detection and a neural classifier for false-positive finding reduction, are described. The system was designed and tested for both internal and sub-pleural nodules. The database used in this study consists of 17 low…
[68Ga]Ga-DATA5m.SA.FAPi PET/CT: Specific Tracer-uptake in Focal Nodular Hyperplasia and potential Role in Liver Tumor Imaging.
2020
Automated detection of patient movement during a CBCT scan based on the projection data.
2015
Objectives To develop an automated procedure to detect patient motion on the projection images acquired during a cone beam computed tomography (CBCT) scan and to evaluate the method's feasibility on small real-world CBCT images in relation to visual assessment. Methods Based on optical flow theory, software was developed using the sequence of the projection images of a CBCT machine for automated detection of patient motion. Averaged acceleration vectors were used as measurement data and compared with visual assessment of the projection images displayed as video. Seventy-nine CBCT data sets (small field-of-view: 40 mm) from our patient database were selected in a sequential fashion and evalu…
Metal artifact reduction in x-ray computed tomography: Inpainting versus missing value
2011
A comparison of algorithms for reduction of metal artifacts in x-ray cone beam computed tomography (CBCT) is presented. In the context of algebraic reconstruction techniques (ART) several inpainting algorithms in the image domain are evaluated against missing data strategies. A GPU-based iterative framework is employed for a meaningful comparison of both. Simulation results from an extended Shepp-Logan phantom and real world dental data are given.
Endodontic re-treatment and restorative treatment of a dens invaginatus type II through new technologies
2019
Background The complex anatomy of dens invaginatus makes access cavity to root canal system difficult, which has an impact on the prognosis of these teeth. A novel technique, based on new technologies, is proposed to make access cavity conservative and guided with minimal dental structure lost. Material and Methods This case report shows the root canal retreatment and the endodontic surgery of a dens invaginatus type II in a left lateral upper incisor previously treated which was affected by a chronic apical abscess and an apical fracture. A Cone Beam Computed Tomography was performed to better diagnosis the dental anatomy. An intraoral scan was performed to get a digital 3D model. A comput…
Evaluation of lens absorbed dose with Cone Beam IGRT procedures
2015
The purpose of this work is to evaluate the absorbed dose to the eye lenses due to the cone beam computed tomography (CBCT) system used to accurately position the patient during head-and-neck image guided procedures. The on-board imaging (OBI) systems (v.1.5) of Clinac iX and TrueBeam (Varian) accelerators were used to evaluate the imparted dose to the eye lenses and some additional points of the head. All CBCT scans were acquired with the Standard-Dose Head protocol from Varian. Doses were measured using thermoluminescence dosimeters (TLDs) placed in an anthropomorphic phantom. TLDs were calibrated at the beam quality used to reduce their energy dependence. Average dose to the lens due to …
SU-E-J-69: Evaluation of the Lens Dose On the Cone Beam IGRT Procedures
2014
Purpose: With the establishment of the IGRT as a standard technique, the extra dose that is given to the patients should be taken into account. Furthermore, it has been a recent decrease of the dose threshold in the lens, reduced to 0.5 Gy (ICRP ref 4825-3093-1464 on 21st April, 2011).The purpose of this work was to evaluate the extra dose that the lens is receive due to the Cone-Beam (CBCT) location systems in Head-and-Neck treatments. Methods: The On-Board Imaging (OBI) v 1.5 of the two Varian accelerators, one Clinac iX and one True Beam, were used to obtain the dose that this OBI version give to the lens in the Head-and-Neck location treatments. All CBCT scans were acquired with the Sta…
Dental CBCT equipment and performance issues
2012
Dental cone beam computed tomography (CBCT), also known as digital volumetric tomography was developed in the late 1990s and is now increasingly available in clinical practice. It can provide high resolution cross-sectional images of teeth and the maxillofacial region with applications in all branches of dentistry. As a new imaging modality, there were no established suspension levels at a European level. A literature review, encompassing scientific, professional publications and existing national guidelines was performed in an attempt to develop a set of suspension levels for dental CBCT, using additional expert opinion from the members of the European Academy of dento-maxillo-facial radio…