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Questions tagged [tomography-reconstruction]

Different from 3D-reconstruction in computer vision, tomography-reconstruction (or tomographic reconstruction) is an algorithm-oriented 3D reconstruction given the 2D measurement from the boundary. Different slices are reconstructed normally by back-projection algorithm, yet many other algorithms for different purpose are rapidly developed every year.

The mathematical basis for tomographic imaging was laid down by Johann Radon. It is applied in Computed Tomography to obtain cross-sectional images of patients. This article applies in general to tomographic reconstruction for all kinds of tomography, but some of the terms and physical descriptions refer directly to X-ray computed tomography.

The questions regarding the tomographic imaging and its reconstruction algorithms may use this tag. The topics include but not limit to: Radon transform, back-projection, Fourier transform, boundary condition problems, finite element method (FEM), X-ray computed tomography/Positron emission tomography, iterative algorithms, conjugate gradient methods.

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MATLAB ifanbeam() reconstructs blurry image

we have been using the ifanbeam function to produce an image of a simulated phantom for medical X-ray imaging. The phantom consists of a water disc with three smaller discs inserted, made of bone, fat, and air. The phantom is positioned in the…
Maggie
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Filtered Back Projection : Cannot reconstruct image using backprojection Algorithm

I am learning FBP and for the last 1 month, I am stuck on Backprojection Algorithm. I have done the following steps till now. Create Sinogram (Radon Transform) Create Filter (hanning Filter: i used the hanning window function to implement the…
Rohit Das
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How to interpolate medical images of different ranges

I would like to get the data of PET and CT interpolated so underlying arrays will have the same dimensions - in normal case it is simple yet I have data set where ranges of the PET and CT scans differ - hence I Would need to first trim the bigger…
Jakub Mitura
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FBP matlab filter design for beam deflection technique

I need your assistance to answer a question about filter design in iradon. Actually, in line of sight projections (beam deflections), in contrary to the other techniques such as absorption, the ram lak filter is replaced by another one whose…
user11822932
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Filtered BackProjection Matlab

I have already implemented the code for BackProjection and it works. Now I have to implement the code for the filtered version, using first ramlak filter and then hamming window. My sinogram has dimension 144x180. My idea is…
Edoardo De Gaspari
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Implementation of Landweber iteration for dynamic Radon Transform in MATLAB

I am working on Dynamic Inverse Problems and Radon transforms. By the term "Dynamic," I mean the object (which eventually I am going to reconstruct its image by having the its measurements), deforms as time evolves. You may imagine the Heart or the…
Siamak Rabienia
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What is the general formula for radon back projection?

Trying to implement a simulation of computed tomography back projection in javascript/HTML5 canvas. Trying to figure the correct approach for dying a back projections and I have been studying this presentation. On pp. 9-13 of the above presentation…
user3220072
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Why iradon returns negative pixel values?

I took 200 projections at a step angle of 1.8 degrees using LabVIEW software. The size of the image is 2748 x 2748 pixels, uint16. Then using Matlab, I load the projection images, do the flat field correction, resize the image by 1/3 and save the…
user8443638
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How to obtain projections for a matrix along a specific line?

Given parametrization of points on line L(t,θ) is x(s):= t cos θ − s sin θ y(s):= t sin θ + s cos θ, where t is the distance from the origin to the line at the angle θ from x-axis, and s is some point on the line. How to take projections of image…
M.B.
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How to create the phantom sinogram from the analytical expression directly?

To create a simulated phantom sinogram, it is common to firstly create the 2-d digital image: I = phantom(xxx); and then apply the rand() transform R = radon(I, theta); However, since the phantom image has its analytical expression, it will be…
lxg
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Removing concentric circles from image in matlab

I have OCT imaging data which I am trying to manipulate: I would like to remove all points bounded by the concentric circles at the center of the image. Up to this point, I was manually specifying a radius for the largest circle and setting all…
user3734522
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Implementation of Radon transform in Matlab, output size

Due to the nature of my problem, I want to evaluate the numerical implementations of the Radon transform in Matlab (i.e. different interpolation methods give different numerical values). while trying to code my own Radon, and compare it to Matlab's…
Ander Biguri
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Direct 2D FFT from sinogram. Polar to cartesian grid interpolation in Matlab

In the theory of tomography imaging a sinogram is recorderded, which is series of projections at different angles of the sample. Taking FFT of this projections gives a slice in polar coordinates of the sample in the frequency space. The command…
Anonymous
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Parallelize matlab algorithm

I'm working on a tomographic algorithm, using SART method. I'm using 2D projections in order to get 3D volume. My main problem is that computation time is really high.. For example, with projections of size 88*75 pixels my program need 5 days to…
user3812144
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Estimate poisson noise in matlab

I have an image with Poisson noise, I need to estimate the noise level in this image(average and variance) Is anyone know a known algorithm that does this, Personally, I have not found. I would be grateful if you answer me.
manuala
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