[Gate-users] Ideal vs. Reality ( How to simulate a real-world PETsystem )

[Mariele Stockhoff]

Dear Zhengzhi,

Your simulations will always be just an approximation of the real-world case and always include assumptions and idealised scenarios. You want to find the trade-off between simulating the system as realistic as possible and "simulation complexity”. You can even go down to simulating each optical photon in the scintillation crystals, but that would increase your computation time to (these days) unreasonable amount of time. The question is thus, how much complexity do you need in order to solve your problems. 
This does not answer your question, but maybe the question why you only find examples of very idealised scanners.

Best wishes,
Mariele

> On 29 Jan 2020, at 06:11, gate-users-request at lists.opengatecollaboration.org wrote:
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>   1. Ideal vs. Reality ( How to simulate a real-world PET	system )
>      (Zhengzhi Liu)
> 
> 
> ----------------------------------------------------------------------
> 
> Message: 1
> Date: Tue, 28 Jan 2020 21:33:11 -0800
> From: Zhengzhi Liu <zliu36 at stanford.edu>
> To: gate-users at lists.opengatecollaboration.org
> Subject: [Gate-users] Ideal vs. Reality ( How to simulate a real-world
> 	PET	system )
> Message-ID:
> 	<CAGLxnT-qCYJbxkTpwDBV0xPUAA29JfY4mRaL5_9Y0r7=DcGgNA at mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
> 
> Dear Gate developers and users,
> 
> Before asking this question, I did much research, like reading GATE User
> Guide v8.0 over and over again, and diving into most of PET related
> simulation code available online (for example, GateContrib
> <https://github.com/OpenGATE/GateContrib>, Gate-develop and
> gate-exercices-master), but I still can't find a single clue on how to
> solve my problem. My problem is to simulate a real-world PET system,
> however, all of the PET systems I found online are ideal systems, in which
> the detectors are only made of crystals. Because of this, they have fewer
> geometries and can be easily attached to all kinds of PET system as shown
> in the attached screenshot.
> 
> However, in a real-world PET system, the detector has a detector box made
> of aluminium or other material, then in the detector, crystals are also
> wrapped with a layer of aluminium. Thus I created 2 for boxes, box1 (filled
> with aluminium), box2 (within box1 and filled with air)  and subtract box2
> from box1 to create detector box. And I did a similar thing to create
> aluminium foil for crystal warper. Because of these extra geometries, I
> find it hard to attach them to a PET system. Because a PET only takes the
> geometries specified in the screenshot.  Then when I attach them to a PET
> system, everything works fine but coincidence sorter. Coincidence sorter
> failed. Either no coincidence event is collected (in cylindricalPET) or
> most of the collected coincidence events are random coincidence event (in
> ecat).
> 
> Has anyone ever simulated a real-world PET system in GATE? If so, have you
> run into this problem? Or Could anyone tell me where I have done wrong?
> 
> Thanks a lot for your precious time reading my email and hopefully you will
> give me some advice.
> 
> 
> Zhengzhi
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