نتایج جستجو برای: beam ct

تعداد نتایج: 242842  

Journal: :BMC Cancer 2021

Abstract Background Chimeric antigen-receptor T-cell and bispecific antibody therapies will likely necessitate a reconsideration of the role autologous stem-cell transplantation (ASCT) in lymphoma. Patients who are to profit from ASCT need be better identified. Methods Here, we investigated value positron emission tomography/computerized tomography (PET/CT) before ASCT. All 521 patients transpl...

2010
O A Zeidan W C Hsi S I Sriprisan S L Meeks J R Palta

A feasibility study of proton beam PET/CT off-line quantitative dosimetry using polymer gels is presented. A newly developed proton-sensitive polymer gel dosimeter (BANG®3-Pro2) is used as a dosimeter and a tissue-equivalent phantom medium for this study. We explore a new approach to correlating measured proton 3-dimensional (3D) dose distributions directly to measured positron emission from in...

Journal: :journal of medical signals and sensors 0
parinaz mortaheb mehdi rezaeian

segmentation and three‑dimensional (3d) visualization of teeth in dental computerized tomography (ct) images are of dentists’ requirements for both abnormalities diagnosis and the treatments such as dental implant and orthodontic planning. on the other hand, dental ct image segmentation is a difficult process because of the specific characteristics of the tooth’s structure. this paper presents ...

Journal: :Computer methods and programs in biomedicine 2012
Mónica Abella Juan José Vaquero Alejandro Sisniega Javier Pascau Á. Udías V. García I. Vidal Manuel Desco

Most small-animal X-ray computed tomography (CT) scanners are based on cone-beam geometry with a flat-panel detector orbiting in a circular trajectory. Image reconstruction in these systems is usually performed by approximate methods based on the algorithm proposed by Feldkamp et al. (FDK). Besides the implementation of the reconstruction algorithm itself, in order to design a real system it is...

2016
Stefan Schaller Marc Kachelrieß Willi A. Kalender

The advanced single–slice rebinning algorithm (ASSR) is a highly accurate and efficient approximative algorithm for cone–beam spiral CT that a) yields high image quality even at large cone angles, b) makes use of available 2D backprojection algorithms/hardware and c) allows for sequential data processing. It uses virtual R–planes (reconstruction planes) that are tilted to optimally fit 180 spir...

Alireza Karimian, Arman Rahmim Mehdi Nasri Nasrabadi, Nematollah Ahmadi

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...

2007
A. Miceli A. Flisch U. Sennhauser F. Casali M. Simon

An X-ray computed tomography (CT) model based on the GEANT4 Monte Carlo code was developed for simulation of a cone-beam CT system for industrial applications. The full simulation of the X-ray tube, object, and area detector was considered. The model was validated through comparison with experimental measurements of different test objects. There is good agreement between the simulated and measu...

2007
S Yartsev T Kron J Van Dyk

Helical tomotherapy (HT) is a novel treatment approach that combines Intensity-Modulate Radiation Therapy (IMRT) delivery with in-built image guidance using megavoltage (MV) CT scanning. The technique utilises a 6 MV linear accelerator mounted on a CT type ring gantry. The beam is collimated to a fan beam, which is intensity modulated using a binary multileaf collimator (MLC). As the patient ad...

2005
Hugo Shi Jeffrey A. Fessler

Statistical methods for tomographic image reconstruction have shown considerable potential for improving image quality in X-ray CT. Penalized-likelihood (PL) image reconstruction methods require maximizing an objective function that is based on the log-likelihood of the sinogram measurements and on a roughness penalty function to control noise. In transmission tomography, PL methods (and MAP me...

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