Read Division of Computer Research and Technology, National Institutes of Health: 1994 Director's Report (Classic Reprint)

Division of Computer Research and Technology, National Institutes of Health: 1994 Director's Report (Classic Reprint)

U S National Institutes of Health

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Description:Excerpt from Division of Computer Research and Technology, National Institutes of Health: 1994 Director's Report A Positron Emission Tomography (pet) image is formed through a computational reconstruction process. The quality of the resulting image and the computation time required to produce it depend on the chosen reconstruction algorithm. Traditionally, Fourier methods the filtered backprojection method, whichis fast but can lead to artifacts) have been used. The expectation maximization (em) method is an iterative solution based on a maximum likelihood criterion. The EM method is known in principle to yield more accurate reconstructions or equivalent reconstructions with lower patient dose than the filtered backprojection. The heavy computational demand of the EM method has, however, limited its use. With the availability of high performance computing, nih scientists can now consider applying the EM algorithm to the problem of truly 3-d reconstruction. The new generation pet scanners allow for the retraction of the tungsten septa shields, which prevent coincident events from being detected outside the axial plane of emission. Retracting the septa increases the angle over which coincidence events can be accepted, and consequently improves detector sensitivity and count rate. However, the amount of detected scatter and random events also increases with wider acceptance angles. Another drawback to retracting the septa is that the size of the reconstruction grows geometrically when using the EM algorithm. In a 3-d EM reconstruction, using typical scanner geometries, the number of projections (ray coincidence events) grows by an order of magnitude, and the size of the probability matrix. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.We have made it easy for you to find a PDF Ebooks without any digging. And by having access to our ebooks online or by storing it on your computer, you have convenient answers with Division of Computer Research and Technology, National Institutes of Health: 1994 Director's Report (Classic Reprint). To get started finding Division of Computer Research and Technology, National Institutes of Health: 1994 Director's Report (Classic Reprint), you are right to find our website which has a comprehensive collection of manuals listed.
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Description: Excerpt from Division of Computer Research and Technology, National Institutes of Health: 1994 Director's Report A Positron Emission Tomography (pet) image is formed through a computational reconstruction process. The quality of the resulting image and the computation time required to produce it depend on the chosen reconstruction algorithm. Traditionally, Fourier methods the filtered backprojection method, whichis fast but can lead to artifacts) have been used. The expectation maximization (em) method is an iterative solution based on a maximum likelihood criterion. The EM method is known in principle to yield more accurate reconstructions or equivalent reconstructions with lower patient dose than the filtered backprojection. The heavy computational demand of the EM method has, however, limited its use. With the availability of high performance computing, nih scientists can now consider applying the EM algorithm to the problem of truly 3-d reconstruction. The new generation pet scanners allow for the retraction of the tungsten septa shields, which prevent coincident events from being detected outside the axial plane of emission. Retracting the septa increases the angle over which coincidence events can be accepted, and consequently improves detector sensitivity and count rate. However, the amount of detected scatter and random events also increases with wider acceptance angles. Another drawback to retracting the septa is that the size of the reconstruction grows geometrically when using the EM algorithm. In a 3-d EM reconstruction, using typical scanner geometries, the number of projections (ray coincidence events) grows by an order of magnitude, and the size of the probability matrix. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.We have made it easy for you to find a PDF Ebooks without any digging. And by having access to our ebooks online or by storing it on your computer, you have convenient answers with Division of Computer Research and Technology, National Institutes of Health: 1994 Director's Report (Classic Reprint). To get started finding Division of Computer Research and Technology, National Institutes of Health: 1994 Director's Report (Classic Reprint), you are right to find our website which has a comprehensive collection of manuals listed.
Our library is the biggest of these that have literally hundreds of thousands of different products represented.

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Division of Computer Research and Technology, National Institutes of Health: 1994 Director's Report (Classic Reprint)

Division of Computer Research and Technology, National Institutes of Health: 1994 Director's Report (Classic Reprint)

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