Voxel Size

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SoyLeyenda
SoyLeyenda on 14 Feb 2012
Edited: Amera Al-funjan on 24 Apr 2017
I have many images from a computed tomography. I have to visualize them in a 3d image. The z spacing (distance between each plane) is 2 mm so I must use a rectangular voxel (not a square one) to get a correct 3d image.
How can i define the voxel size?
Thank you
  1 Comment
Sean de Wolski
Sean de Wolski on 14 Feb 2012
I don't understand, your x/y are the same (we hope) and the difference between slices is different (2mm). You have all of the information you need for whatever purpose you want. You could use interp1() to interpolate to a cubic voxels or you could use meshgrid() to properly define the grid. Otherwise, what measurement do you need voxel size for?

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Answers (4)

Image Analyst
Image Analyst on 14 Feb 2012
Your instrument knows. The voxel size is put into the header of your image by your CT instrument when it reconstructs your image. You just have to look in the header. I have 3 CT instruments from 2 manufacturers and this is the way it is done on all of them.

SoyLeyenda
SoyLeyenda on 14 Feb 2012
I don't have any instruments. I only have DICOM images and matlab for the 3d reconstruction. It's for a investigation project.
  1 Comment
Image Analyst
Image Analyst on 14 Feb 2012
Then it should be saved in the DICOM header. Did you look there? Anyway, the voxel size is just the x-size times the y-size times the slice thickness, which is usually the same as the slice separation.

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Amera Al-funjan
Amera Al-funjan on 22 Apr 2017
I have CT lung DICOM images and I could cluster the nodules and vessels in the lungs of patient stack images that contain 6 nodules in different images of stack and I want to visualize the nodule clusters in the 3D plot in different levels with their voxel in order to visualize the merging between radiologists nodules and the clustered nodules in my system . The problem is that I need to convert the clusters unit(pixels) to radiologists unit (mm). How can I convert the unit from pixels to mm? if I have pixel spacing, thickness, cluster locations, cluster centers, cluster diameter and cluster area.
  2 Comments
Amera Al-funjan
Amera Al-funjan on 24 Apr 2017
Dear Image Analyst, Could you explain more and answer the questions below: 1. what do you mean by "Multiply the row and column distances",is that meaning the row and column distances of pixel spacing or something else. 2. Either"separations by the pixel spacing in mm or cm" I could not completely understand .Could you write any formula or equation with clarify more? Your advise would be of great help to me. Thanks

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sapna jaiswal
sapna jaiswal on 24 Apr 2017
Hi Image Analyst, I am analysing MicroCT images for various 3D representations. The final output files give values in pixels. The voxel size of my images are 1x1x1(as I can see from the image properties). Could you please advice how to convert the output areas and volumes with units as mm or micrometers? Your advise would be of great help to me. Thanks

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