[Gate-users] Material image dose scoring

[Emmanuel Marfo]

Thanks, Sir for your quick response. I think is very helpful with the insightful and the approach you have outlined. I will look at it to see if I can use it for my purpose. Will let you and the GATE users know of the progress.  I really appreciate the help. I
Best regards,

Emmanuel

________________________________
From: Maikol Salas Ramirez <mmsalas at gmail.com>
Sent: Wednesday, 13 June 2018 12:47:57 PM
To: Emmanuel Marfo
Subject: Re: [Gate-users] Material image dose scoring

Hi Emmanuel,

I think, it is not possible to use the material decomposed images directly in GATE without a table, one option is to create mask of each material and a second is to create mesh volumes of each material and used them like  a child volumes of the contour of the normal ct image.

One option to start is create fraction images:

When you use material decomposed images, you have mass conservation (it depend of your spectral method, but normally is like that, you have to check it), it means Mass_Fraction(HA) + Mass(Lipid) _Fraction + Mass(Water)_Fraction = 1.

The problem here is how to transform your images in fraction images, I had a previous experience but with Water/Fat images but from MRI. For my MRI experiment I calculated the fat fraction and the water fraction (1-fat fraction).

In your case you can do the same:
1- HA_Fraction = HA_Voxel_Value / ( HA_Voxel_Value +  Lipid_Voxel_Value +  Water_Voxel_Value).
2- Lipid_Fraction = Lipid_Voxel_Value / ( HA_Voxel_Value +  Lipid_Voxel_Value +  Water_Voxel_Value).
3- Water_Fraction = Water_Voxel_Value / ( HA_Voxel_Value +  Lipid_Voxel_Value +  Water_Voxel_Value).

I did this calculation with your images using ImageJ and it works pretty easy, you just need to sum all the three images and divide each one by the sum, if you chose one voxel you will see that the sum is 1. The attached image shows the three images.

The only artifact here is in voxel with air or with a zero value you will have NaN value, you have to fix them (given the zero value), ImageJ has an option to do that.

--------------
This is what I can see, the main point is that a normal voxel in a CT images has a composition of material and what you have in each voxel is a effective atomic number and effective density, with spectral CT you separate the material and you have to take care to use the individual images because you lost anatomical information information.

Sorry I think, I could not help you to much.

Best regards
Maikol


2018-06-12 10:50 GMT+02:00 Emmanuel Marfo <emmanuel.marfo at postgrad.otago.ac.nz<mailto:emmanuel.marfo at postgrad.otago.ac.nz>>:

Hello

Thanks for the quick response. Please, the images are density images obtained by dividing linear attenuation(energy information) values by mass attenuation(material basis).

Attached is a dropbox link of a folder containing the material decomposed images for your assessment. thanks

https://www.dropbox.com/sh/zxfio5azk4q6osb/AADw0a1BMYQiPnqFjMgwdCnYa?dl=0

[https://cfl.dropboxstatic.com/static/images/icons128/folder_dropbox.png]<https://www.dropbox.com/sh/zxfio5azk4q6osb/AADw0a1BMYQiPnqFjMgwdCnYa?dl=0>

material images from spectral CT<https://www.dropbox.com/sh/zxfio5azk4q6osb/AADw0a1BMYQiPnqFjMgwdCnYa?dl=0>
www.dropbox.com<http://www.dropbox.com>
Shared with Dropbox




Best regards,

Emmanuel

________________________________
From: Maikol Salas Ramirez <mmsalas at gmail.com<mailto:mmsalas at gmail.com>>
Sent: Tuesday, 12 June 2018 5:45:25 PM
To: Emmanuel Marfo
Cc: gate-users at lists.opengatecollaboration.org<mailto:gate-users at lists.opengatecollaboration.org>
Subject: Re: [Gate-users] Material image dose scoring

Hi Emmanuel,

When you said material decomposed image, are you talking about Rho/Z image (effective density and atomic number - image)?
What info do you have in your image?

Best regards
Maikol

El El mar, 12 jun 2018 a las 0:34, Emmanuel Marfo <emmanuel.marfo at postgrad.otago.ac.nz<mailto:emmanuel.marfo at postgrad.otago.ac.nz>> escribió:

Hello Gate Users,

Please, I need help on this or if anyone has the knowledge of how it can be done I would be grateful. I am using a spectral CT system to obtained material decomposed image based on mass attenuation and energy information. I want to do dose deposition on the material decomposed images without the use of Schneider material converter employed in GATE.  My problem is I want to know if GATE architecture supports it and second I can not import the material decomposed image into GATE because is always requesting for a conversion text file. Can I bypass it? Can someone help me, please? Thanks


Best regards,

Emmanuel Marfo

Student

University of Otago

_______________________________________________
Gate-users mailing list
Gate-users at lists.opengatecollaboration.org<mailto:Gate-users at lists.opengatecollaboration.org>
http://lists.opengatecollaboration.org/mailman/listinfo/gate-users

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.opengatecollaboration.org/pipermail/gate-users/attachments/20180613/f2f73164/attachment-0001.html>