[Rtk-users] Rtkfdk Geometry Question

[Ali Yazdanpanah]

Hi,

I have a question from you about the CT reconstruction, I would really
appreciate if you can help me with this.

I have the geometry as described in following and I am trying to run the
rtkfdk code from RTK.


% parameters % % % % % % %

param.nx = 500; % number of voxels
param.ny = 500;
param.nz = 500;


param.sx = 5000; % mm (real size)
param.sy = 5000; % mm
param.sz = 5000; % mm


%The real detector panel pixel density (number of pixels)
param.nu = 36; % number of pixels
param.nv = 100;

% Detector setting (real size)
param.su = 7200; % mm (real size)
param.sv = 9200; % mm


% X-ray source and detector setting
param.DSD = 32900; % Distance source to detector
param.DSO = 27400; % X-ray source to object axis distance


% angle setting
param.dir = +1; % gantry rotating direction (clock wise/ counter clockwise)
param.dang = 5; % angular step size (deg)
param.deg = 0:param.dang:360-1; % you can change
param.deg = param.deg*param.dir;
param.nProj = length(param.deg);

param.parker = 0; % data with 360 deg -> param.parker = 0 , data less than
360 deg -> param.parker=1

param.filter='ram-lak'; % high pass filter


param.dx = param.sx/param.nx; % single voxel size
param.dy = param.sy/param.ny;
param.dz = param.sz/param.nz;
param.du = param.su/param.nu;
param.dv = param.sv/param.nv;
param.off_u = 0; param.off_v = 0; % detector rotation shift (real size)


% Geometry calculation % % %
param.xs = [-(param.nx-1)/2:1:(param.nx-1)/2]*param.dx;
param.ys = [-(param.ny-1)/2:1:(param.ny-1)/2]*param.dy;
param.zs = [-(param.nz-1)/2:1:(param.nz-1)/2]*param.dz;
param.us = (-(param.nu-1)/2:1:(param.nu-1)/2)*param.du + param.off_u;
param.vs = (-(param.nv-1)/2:1:(param.nv-1)/2)*param.dv + param.off_v;



So basically my final projection array has 36 * 100 * 72(=angles: 0 : 5 :
360).
But I got confused how to set the geometry parameters in RTK
I followed the rtkfdk tutorial but I can’t get any result using this method

I did the following:

1-       Create geometry.xml using these parameters:

  nproj = 72 ;
  first_angle = 0 ;
  arc = 360 ;
  sid = 27400 ;
  sdd = 32900 ;
  proj_iso_x = 0;
  proj_iso_y = 0;
  out_angle = 0 ;
  in_angle = 0 ;
  source_x = 0;
  source_y = 0 ;

2-       Create my own mha file (WriteMhaFile.m) from my projection array
(36*100*72) using a matlab code with following properties:
Voxel size = [0.1 0.1 0.1]
Offset = [1 1 1]


3-       Then run the:
rtkfdk -p . -r projections.mha -o fdk.mha -g geometry.xml --spacing 0.1
--dimension 500


Could you please tell me if I am setting the geometry correctly?
Also, is there any other way to create my own mha file?

Thank you in advance and looking forward to hear back from you.
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