segmentation masks to RT struct

[Michael Lempart]

Hi all,

Iam trying to convert segmentation masks to RT struct DICOM files, where pixel (or voxel) values ca be 0 (background), 1 (segmentation 1), 2 (segmentation 2) or 3(segmentation 3).

It works just fine with a single structure, but if I try to convert all three masks to a common RT struct file, one structure (3) is missing, though it seems like plastimatch combines mask 2 and 3.

Does anyone have had this kind of issue?

Thanks in advance,

Cheers,

Mike

[tim.birtwhistle]

Hi Mike, 

I found something similar to this. I think the DICOM converter is expecting the mask values to be powers of two so it thinks segmentation 3 is a combination of 1 and 2. This is useful when the structures might overlap. One way around this would be to change the pixel values of the mask if you can. If segmentation 3 had the value 4 it should work.

You might need to alter your list file too if the structure labels don't agree with what you expect but that might not be necessary. 

Thanks, 

Tim

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[Michael Lempart]

Hi Tim and thanks for your reply!

I will give it a try and I think you might be right. I observed that one structure in the RT struct dcm seems to be a combination of two of the masks. 

Regards,

Michael 

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[Sharp, Gregory C.]

Hi Michael,

 

The --output-ss-img option does indeed use a separate bit for each structure as Tim says.  This allows overlapping structures.

 

To do what you want, you should use --output-labelmap.  This does not support overlapping structures, and gives you the contours as 1, 2, 3, etc.

 

Greg

 

From: 'Michael Lempart' via Plastimatch <plast...@googlegroups.com>
Sent: Friday, December 11, 2020 2:46 PM
To: plast...@googlegroups.com
Subject: Re: [Plastimatch] segmentation masks to RT struct

 

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