How to build up a CT scanner based on Geant4?

Applications
1

Hi all,
I noticed that some literatures said they developed a Monte Carlo simulator of computed tomography(CT) based on geant4 toolkit, but they didn’t open the source code. How can I build up a CT scanner? I am familair with x-ray radiography simulation through geant4, but only single angle imaging. For CT scanner, it needs multi-angle scanning, and the X-ray tube and detectors or the inspected object is required to rotate. How to make the machine rotate to get multi-angles scanning in geant4? By the way, is there any examples?

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2

Hi @repan,
I also have the same purpose as you.

I created a application to get single angle image from the Cone Beam CT. To get full rotated images, I think we should implement multi runs. Between 2 runs, we will rotate the phantom/source+detector geometry. But I don’t still implement this ideal yet. I hope that there is anyone can help us in this post.

3

Hi @HungBuiTien,
yeah, you are right. For CT imaging one often need 900 views (projections), so if we rotate the object/source+detectors is not a practical method.
I found opengate can simulate CT. Opengate is developed from geant4, and can be defined by user commands.While I still want to build up a program by myself through geant4 since geant4 is based on c++ and can store output into ROOT format file.

4

Dear @repan,
GATE is also a tool that will help us build a CT simulation easily via macro lines. I tried GATE before. If you need my source code, I can share it with you.

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5

Hi @HungBuiTien,
Thanks for your kindness. I will find you when I need the source code of GATE.We can keep in touch in the future.

6

Hi @HungBuiTien, I am a student who wants to model a CT scanner now. If you don’t mind, can you share the GATE code of the CT scanner?? I would be very grateful if you could share.

7

Hi, HungBuiTien.
Its more easyer to achieve by rotating the phantom rather than souce + detectors.

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8

Hello, please I’m very new to geant4, could you show me how?

9

Hi @yangshiyan,
May I ask how to make the object rotate around a specific
aixs in geant4? Can you share your experiences or some useful codes?

Best regards
Renqi

10

Hi, @ repan
In my work, I use these commands:

G4Tubs* parPhantom =
new G4Tubs(“outPhan”, 0, 0.5outDia, 0.5outLen, 0, CLHEP::twopi); // define a cylinder parPhanLV =
new G4LogicalVolume(parPhantom, matResin, “outPhanLV”);
G4RotationMatrix* pRot = new G4RotationMatrix();
pRot->rotateY(-90.deg);
**pRot->rotateZ(m_angledeg);** // Here m_angle is the object ratation angle, Its value can be passed form main(), the argv variable
pos = G4ThreeVector(0,0,0); //move back to world center
new G4PVPlacement(pRot,pos,parPhanLV,“parPhanPhysics”,worldLV, false,0,fCheckOverlaps);
parPhanLV->SetVisAttributes(new G4VisAttributes(G4Color(0.8275, 0.8275, 0.8275))); // grey

11

Hi @yangshiyan,
Thanks for your reply. I think your message is helpful for others. I can understand your strategy. But there are still some puzzles remind. Can you clarify how to pass the rotational angle m_angle from main() to DetectorConstruction class? And how do you execute the program to loop over angles?

Best regards