background cone beam computed tomography (ct) has recently become effective for oral and maxillofacial imaging. objectives the aim of this study was to assess the knowledge of dentists regarding cone beam computed tomography. materials and methods in this descriptive cross sectional study, a questionnaire regarding cone-beam computed tomography (cbct) was distributed amongst 100 dentists (gener...

Particle beam treatment allows accurate dose delivery onto carcinogen tissue. The reachable accuracy is limited by patient alignment errors relative to the beam source. Errors can be corrected manually or by automatic comparison of two X-ray images to a CT-scan but correction mostly does not cover all degrees of freedom (DoF). In this contribution we present a solution that makes use of one X-r...

With cone beam CT long computation and a large amount of memory is required. The majority of the computation is in the backprojection step. We have investigated the use of parallel methods on workstation clusters using MPI to overcome both the long processing t ime and lessen memory requirements on individual workstations. We used the asynchronous MPI implementation t o reconstruct a 25€i3 volu...

The cone-beam approach for image reconstruction attracts an increasing attention in various applications, especially medical imaging. Previously, the traditional practical cone-beam reconstruction method, the Feldkamp algorithm, was generalized into the case of spiral/helical scanning loci with equispatial cone-beam projection data. In this paper, we formulated the generalized Feldkamp algorith...

Introduction: The CT machine utilizes a bowtie filter to shape the X-ray beam and remove lower energy photons. Configuration of this bowtie filter is complex and its geometry is often not available in detail. It causes the CT dose index (CTDI) be with the different values in measurement versus Monte Carlo simulation studies and other analytical calculations. It is important esp...

Electron-beam or ultrafast computerized tomographic (CT) scanning provides a convenient and sensitive means of detecting coronary calcification, which is an early index of atherosclerosis. The procedure has strong negative predictive power for the presence of coronary artery disease, but a limited ability to predict disease severity. However, preliminary indications are that it is as good or be...

This paper presents mechanical behavior of a functionally graded (FG) cantilever micro-beam subjected to a nonlinear electrostatic pressure and thermal moment considering effects of material length scale parameters. Material properties through the beam thickness direction are graded. The top surface of the micro-beam is made of pure metal and the bottom surface from a mixture of metal and ceram...

CT findings of the base of the neck are often degraded by beam-hardening artifact from the shoulder girdle. This artifact can be reduced by placing the patient in a "swimmer's" position, a supine position in which the patient has one arm fully abducted and the other arm lowered. We selectively employed swimmer's CT in patients between January 1999 and December 2002 when standard (arms-down) CT ...

Background: Cone-beam computed tomography (CBCT) scanners for image-guided radiotherapy are in clinical use today, but there has been no consensus on uniform acceptance to verify the CBCT image quality yet. The present work proposed new methods to fully evaluate the performance of CBCT in its three-dimensional (3D) reconstruction space. Materials and Methods: Compared to the traditional methods...

Introduction. Spatially registering SPECT with CT makes it possible to anatomically localize SPECT tracers. In this study, an accurate method for the coregistration of ultra-high-resolution SPECT volumes and multiple cone-beam CT volumes is developed and validated, which does not require markers during animal scanning. Methods. Transferable animal beds were developed with an accurate mounting i...