Create DRR image from Chest CT scan

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1

Hi everyone,

We are trying to convert 3D volumetric CT images to chest Xray (for a sake of comparison with another dataset). We use this example:

The projection results in radiography-looking images but it is visually different from what we expected. Here is an example of what we get:

image
image.jpg1854×799 285 KB

and example what we thought we can get:

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image.jpg1024×914 214 KB

I think we are missing some transformation on intensity right before the projection and I don’t what should be. I searched for it and I found this paper:

Is there any transformation on the intensity of 3D CT image that results in 2D projection looking more like chest Xray? Is there anything like that paper implemented in ITK?
Also, if someone can provide some insight into how to use the available options with the GetDRRSiddonJacobsRayTracing method.

Thanks

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Hello @sumedha_singla ! :wave:

It looks like a good start.

The X-ray example looks to have more soft-tissue content from the shoulder, etc. So, beam path selection and interrogated volume selection may help.

Also, Siddon-Jacobs projection is also available in OpenRTK:

which has more configuration options.

HTH,
Matt

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Hi Matt,
Thank you for your prompt reply. You are the best. I will look into your suggestion and post any followup question.
Best,
Sumedha

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Hi,

Can you please elaborate on interrogated volume selection. Also, I have build OpenRTK. Can you please point me to the specific filter that provide this functionality. Meanwhile, I played around with the example in ITK filtering: “DigitallyReconstructedRadiograph1”. Its looks very similar to InsightSoftwareConsortium/ITKTwoProjectionRegistration/blob/master/test/GetDRRSiddonJacobsRayTracing.cxx
But there is no option to choose projection angle. How can we provide projection angle in “DigitallyReconstructedRadiograph1” example?

Best,
Sumedha

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That is, are the rays passing through the muscles in the shoulder, for example?

Look for examples that use rtk::ForwardProjectionImageFilter, e.g.

RTK is recommended for the most flexibilty.

HTH,
Matt

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Hi, I am also trying to use DRR to create biplanar xrays from CT files. I don’t know c++, I want to use python. I spent hours to compile ITK modules, now trying to understand the examples, but I don’t have time for this for this week at least. Is it possible to use python without compiling ITK files? How can I do it?

Thanks in advance
Gokce

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@Gokce_Guven you can directly use the ITK Python package from the Python Package Index:

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@jhlegarreta Thanks a lot for your fast response, I will check it :slight_smile:

Best
Gokce

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There is also the itk-rtk Python package:

pip install itk-rtk
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@Gokce_Guven were you able to get DRR running with python?

Thanks,
Tejas

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Hello @sumedha_singla @matt.mccormick
I am quite new to ITK. Could you help to simply explain how to do the input of CT series (what i have a series of .dcm). ? Do I need to convert to other format for itkImageFileReader ?

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Take a look at this example of how to convert a DICOM series into a single 3D image. Then you can use itkImageFileReader on that single image. Otherwise you will have to use the DICOM series reading code if you don’t want to convert first.

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