[Castor-users] Attenuation correction with SPECT detector

[STUTE Simon]

Dear Hyung-Joo Choi,


I suggest that you always reply to the mailing list because this kind of discussion may be helpful for other people.


It is hard to tell what is wrong from these images.

You should go step by step.

Before trying to correct for the attenuation, did you get a good image with CASToR without attenuation correction ?


Simon


________________________________
De : ‍최형주(원주학부학생/보건과학대학 방사선학과) <hyungjoochoi7558 at yonsei.ac.kr>
Envoyé : mercredi 23 septembre 2020 04:43
À : STUTE Simon
Objet : Re: [Castor-users] Attenuation correction with SPECT detector

Dear Simon,

Thank you for answering my troubles.

I checked my file, the data is "histo-mode".
The sinogram data used in this case was simulated on GATE and I used matlab to make a ".Cdf" file.
The file named "6X6_generation_case1.sin" is data from GATE, and the "all_energy_case_1.Cdf" is the data that was made with matlab.

The figure on the left side is the image reconstructed with FBP, and the right is the image to apply 'iterative' and 'attenuation correction'.
When I made the mumap, the structure which is occurring attenuation was defined only in the center of the image.
However the result of the iterative method was different from what I expected.

What am I doing wrong?

Hyung-Joo Choi.
[image.png][image.png]

2020년 9월 22일 (화) 오후 11:06, STUTE Simon <simon.stute at chu-nantes.fr<mailto:simon.stute at chu-nantes.fr>>님이 작성:

Hi,


The use of list-mode data implies the computation of the global sensitivity before starting iterations of the reconstruction algorithm.


The computation of the sensitivity image for SPECT is not implemented yet so you should end up with an error thrown by the oSensitivityGenerator::Initialize().


Are you really doing list-mode SPECT ? Did you implement the computation of this sensitivity image based on the SPECT scanner ?


The mumap image is automatically interpolated and adjusted on the reconstructed image if image samplings are different. Did you correctly set the voxel dimensions in the mumap ? What do you mean by "expanded" ?


Simon



________________________________
De : Castor-users <castor-users-bounces at lists.castor-project.org<mailto:castor-users-bounces at lists.castor-project.org>> de la part de ‍최형주(원주학부학생/보건과학대학 방사선학과) <hyungjoochoi7558 at yonsei.ac.kr<mailto:hyungjoochoi7558 at yonsei.ac.kr>>
Envoyé : mardi 22 septembre 2020 11:00
À : castor-users at lists.castor-project.org<mailto:castor-users at lists.castor-project.org>
Objet : [Castor-users] Attenuation correction with SPECT detector

Dear all,

I am having a problem with attenuation correction. I have been studying a monitoring method for the spent fuel assembly using the SPECT system. The image was reconstructed using the filtered back projection method. However, the image reconstructed with the FBP method showed low-intensity on the center of the image. So I downloaded CASToR software to improve the image of spent fuel assembly. At first, I used the joseph projector using -proj to test CASToR software. The joseph projector does not permit attenuation correction. And now, I have been using incrementalSiddon projector for attenuation correction. I made a mumap using matlab and the ground truth image. The mumap worked, but the reconstructed image was different from what I had expected. It seems that the mumap was expanded.

Does anyone know how to apply mumap for attenuation correction, or what I do wrong? I used list-mode SPECT data with GATE for 4500 second. And the detector used in my study is a 64 channel multi array.

Thanks in advance.
Hyung-Joo Choi


--
-------------------------------------------------------------------------
Hyung Joo Choi
before graduation
RaPhyA (Radiation Physics Analysis Lab.)
Dept. of Radiation Convergence Engineering, Yonsei University
Baekwoon hall Rm# 429, Yonsei University,
1 Yonseidae-gil, Wounju, Gangwon 220-710, Korea
Office: +82-33-760-2892, Fax: +82-33-760-2892, Cell: +82-10-2420-7558
E-mail: hyungjoochoi7558 at yonsei.ac.kr<mailto:hyungjoochoi7558 at yonsei.ac.kr>
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