Dicom RD file

[adnan Jafar]

Hi,

I am working with a DICOM RD file  (from brachytherapy) in MATLAB, and the dose volume dimensions I obtain are 237 x 226 x 226 (rows x columns x frames). The pixel spacing for both the x and y axes is 1, and the spacing between the GridFrameOffsetVector is also 1.

However, the CT slices have a volume size of 512 x 512 x 348 (rows*columns*slices), with pixel spacing for the x and y axes being 0.5, and the slice thickness is 1.

I have two questions:

1. The x and y coordinates (code below) I get from the RD file do not cover the full x,y z range of the CT slice coordinates when taking into account their respective pixel spacings.  I was assuming RD dicom dose size should be 256*256* 174 instead of 237*226*226, giving its spacing dimensions. Is this normal?

2. How can I interpolate the dose values onto the intermediate voxels of the CT slice grid, considering the RD file has a pixel spacing of 1 for both x and y axes? Are there any MATLAB or Python tools that can help map the dose volume from the RD DICOM file onto the full CT coordinate grid? Thanks.
   
   % Code to find x, y, z from Dicom RD file.
   resolution = double(dcm.PixelSpacing);
   dx = resolution(1); % dx is 1
   x = dcm.ImagePositionPatient(1) + (0:(double(dcm.Columns) - 1)) * dx;
   dy = resolution(2); % dy is also 1
   y = dcm.ImagePositionPatient(2) + (0:(double(dcm.Rows) - 1)) * dy;
   z = dcm.GridFrameOffsetVector + dcm.ImagePositionPatient(3);
   
   Regards, Adnan