Journal ArticleDOI
Effect of scattered radiation on image noise in cone beam CT.
Reads0
Chats0
TLDR
This work estimated the scatter fractions and effects of scatter on image noise, and derived a relationship between the noise in a reconstructed image and in an x-ray intensity measurement, and estimated the image noise under relevant clinical conditions.Abstract:
Cone beam CT has a capability for the 3-dimensional imaging of large volumes with isotropic resolution, and has a potentiality for 4-dimensional imaging (dynamic volume imaging), because cone beam CT acquires data of a large volume with one rotation of an x-ray tube-detector pair. However, one of the potential drawbacks of cone beam CT is a larger amount of scattered x-rays, which may enhance the noise in reconstructed images, and thus affect the low-contrast detectablity. Our aim in this work was to estimate the scatter fractions and effects of scatter on image noise, and to seek methods of improving image quality in cone beam CT. First we derived a relationship between the noise in a reconstructed image and in an x-ray intensity measurement. Then we estimated the scatter to primary ratios in x-ray measurements using a Monte-Carlo simulation. From these we estimated the image noise under relevant clinical conditions. The results showed that the scattered radiation made a substantial contribution to the image noise. However, focused collimators could improve it by decreasing the scattered radiation drastically while keeping the primary radiation at nearly the same level. A conventional grid also improved the image noise, though the improvement was less than that of focused collimators.read more
Citations
More filters
Journal ArticleDOI
A simple, direct method for x-ray scatter estimation and correction in digital radiography and cone-beam CT.
Jeffrey H. Siewerdsen,Michael J. Daly,B. Bakhtiar,Douglas J. Moseley,Samuel Richard,Harald Keller,David A. Jaffray +6 more
TL;DR: A simple scatter correction method in which scatter fluence is estimated directly in each projection from pixel values near the edge of the detector behind the collimator leaves, which provides significant reduction in scatter artifacts without compromise in contrast-to-noise ratio (CNR).
Journal ArticleDOI
Flat-detector computed tomography (FD-CT).
TL;DR: FD-CT is not aimed at challenging standard clinical CT as regards to the typical diagnostic examinations; but it has already proven unique for a number of dedicated CT applications, offering distinct practical advantages, above all the availability of immediate CT imaging in the interventional suite or the operating room.
Journal ArticleDOI
The influence of antiscatter grids on soft-tissue detectability in cone-beam computed tomography with flat-panel detectors.
TL;DR: The results suggest that although grids reduce scatter artifacts and improve subject contrast, there is little strong motivation for the use of grids in cone-beam CT in terms of CNR and overall image quality under most circumstances.
Journal ArticleDOI
Modelling the physics in the iterative reconstruction for transmission computed tomography
TL;DR: Discretization issues and modelling of finite spatial resolution, Compton scatter in the scanned object, data noise and the energy spectrum are reviewed.
Journal ArticleDOI
A general framework and review of scatter correction methods in x-ray cone-beam computerized tomography. Part 1: Scatter compensation approaches.
TL;DR: A main result is the preservation of differential-signal-to-noise-ratio (dSNR) in CT projection data by ideal scatter correction by incorporating scatter compensation approaches into a statistical framework for noise minimization.
References
More filters
Journal Article
Practical cone-beam algorithm
TL;DR: In this article, a convolution-backprojection formula is deduced for direct reconstruction of a three-dimensional density function from a set of two-dimensional projections, which has useful properties, including errors that are relatively small in many practical instances and a form that leads to convenient computation.
Journal ArticleDOI
Practical cone-beam algorithm
TL;DR: In this article, a convolution-backprojection formula is deduced for direct reconstruction of a three-dimensional density function from a set of two-dimensional projections, which has useful properties, including errors that are relatively small in many practical instances and a form that leads to convenient computation.
Journal ArticleDOI
The Fourier reconstruction of a head section
L. A. Shepp,B. F. Logan +1 more
TL;DR: The authors compare the Fourier algorithm and a search algorithm using a simulated phantom to speed the search algorithm by using fewer interactions leaves decreased resolution in the region just inside the skull which could mask a subdural hematoma.
Journal ArticleDOI
Atomic form factors, incoherent scattering functions, and photon scattering cross sections
TL;DR: In this paper, the atomic form factor and the incoherent scattering function were derived from available state-of-the-art theoretical data, including the Pirenne formulas for Z=1, configuration-into-action results by Brown using Brown‐Fontana and Weiss correlated wavefunctions for Z =2 to 6 non-relativistic Hartree‐Fock results by Cromer for Z ≥ 0.005 A−1 to 109 A− 1, for all elements A=1 to 100.
Journal ArticleDOI
Photon mass attenuation and energy-absorption coefficients
TL;DR: In this paper, mass attenuation coefficients μ/ϱ and mass energy-absorption coefficients μ cn/ϑ are tabulated in units of m 2 kg −1 for photon energies 1 keV to 20 MeV for 40 elements ranging from hydrogen (Z = 1) to uranium (Z= 92).