[Gate-users] How to simulate Lu-176 in LSO crystal

Fri Jun 12 19:41:18 CEST 2020

Thanks, Bryan for the clarification.

I definitely misunderstood the command "confine" earlier. Now it seems
clear to me, but it comes with a couple of concerns. It looks like you
created a very large Lu176 source to encompass/embody your crystals. But by
confining the source to crystal_P, does it mean that the source is only
activated within crystal_P and outside crystal_P the source is not
activated?  If so, how can the source strength inside crystal_P be
correctly calculated and implemented?

My second question is, why does "confine" recognize crystal_P as the
assembly of all crystals created with repeaters, but "attachTo" command
does not recognize crystal_P at all?  Meanwhile, crystal only represents
the very first one crystal created with a repeater. Is this an internal
bug?  If "attachTo" recognized crystal_P, then none of these would have
become a problem. I really want to bring this up to the attention of the
developers.

Thanks a lot for your help.
Albert

On Fri, Jun 12, 2020 at 5:31 AM Bryan McIntosh <mcintoshster at gmail.com>
wrote:

> Hi Albert,
>
> Ashok's code looks very similar to what I had sent, and it only uses the
> confine command, NOT attach. The whole idea behind the way that I
> implemented this method for simulating a Lu-176 ion source was to make the
> source large enough to fill the entire scanner volume, then confine the
> activity to the crystal only; again, I have not tested it under a newer
> version of GATE to verify that it still works, and it may not.
>
> Again, be advised that this does increase the simulation time by a
> significant amount since you're adding an ion source that has a lot of beta
> and gamma interactions inside the crystal volume; if you can simulate the
> noise due to background Lu-176 using the "noise" modules as Emilie and
> Maxime suggested earlier, I highly recommend doing that instead. I know
> that computers have significantly faster single-thread performance than in
> 2010 and 2011, but the fewer particles that need to be simulated the better!
>
> Best regards,
>
> -Bryan McIntosh
>
> On Thu, Jun 11, 2020 at 6:20 PM Albert Grace Lieu <albertnew2018 at gmail.com>
> wrote:
>
>> Hi Bryan,
>>
>> Thank you very much for your paper and help. I tried your code for a
>> couple of times, it does not confine/attach Lu176 to the crystal. Instead,
>> there is only one source showed up at the center of the world. Also, your
>> code does not look like confining a source to crystals, because of the
>> shape and size of the source. It is much larger than any possible detector
>> crystal. My problem now is that I can only attach Lu176 to only one
>> crystal, not all of them. Could you please give me any further help,
>> please?
>>
>> Thanks a lot.
>> Zhengzhi
>>
>> On Thu, Jun 11, 2020 at 3:02 PM Bryan McIntosh <mcintoshster at gmail.com>
>> wrote:
>>
>>> Hello Zhengzhi,
>>>
>>> I wrote the second paper that you linked, and it looks like your initial
>>> idea was in the right direction; I made a Lu-176 source that encompassed
>>> the entire detector. The difference is that I used the "confine" command
>>> for the source, not "attach;" the complete code was as follows:
>>>
>>> #Single intrinsic source; confined to crystal
>>> /gate/source/addSource intrinsic
>>> /gate/source/intrinsic/gps/particle ion
>>> /gate/source/intrinsic/gps/ion 71 176 0 0
>>> /gate/source/intrinsic/gps/monoenergy 0. keV #Super important!
>>> /gate/source/intrinsic/gps/angtype iso
>>> /gate/source/intrinsic/gps/type Volume
>>> /gate/source/intrinsic/gps/shape Cylinder
>>> /gate/source/intrinsic/gps/radius 14.5 cm
>>> /gate/source/intrinsic/gps/halfz 70.1 mm
>>> /gate/source/intrinsic/setActivity 20192.56 Bq
>>> /gate/source/intrinsic/gps/confine crystal_P
>>>
>>> This worked for a system where the crystal volume was named called
>>> "crystal," and was duplicated using a cubic array. Be advised that the
>>> activity and dimensions of the source were set up to match the Siemens
>>> Inveon dPET system; adjust the size and activity accordingly for your
>>> particular system. I used an activity of 276 Bq/cm^3 of LSO crystal,
>>> calculated from a 2.6% concentration of Lu-176 in the Lu atoms making up
>>> the crystal. This is different than the 250 Bq/cm^3 that is often used,
>>> since that number was from a measurement that was 250 counts per
>>> second/cm^3, not necessarily Bq.
>>>
>>> This code worked when I ran it back in 2011; I haven't tested it on a
>>> GATE version newer than 6.2. I THINK it will work with newer versions of
>>> GATE, but your results may vary!
>>>
>>> Good luck!
>>>
>>> -Bryan McIntosh
>>>
>>> On Thu, Jun 11, 2020 at 1:37 PM <
>>> gate-users-request at lists.opengatecollaboration.org> wrote:
>>>
>>>> ------------------------------
>>>>
>>>> Message: 2
>>>> Date: Wed, 10 Jun 2020 22:09:13 -0700
>>>> From: Albert Grace Lieu <albertnew2018 at gmail.com>
>>>> To: gate-users <gate-users at lists.opengatecollaboration.org>
>>>> Cc: Peter Olcott <polcott at reflexion.com>
>>>> Subject: [Gate-users] How to simulate Lu-176 in LSO crystal
>>>> Message-ID:
>>>>         <CAGLxnT-Qdh-NZ8KoBOQuH=
>>>> zszHP+zw5f_aeD5ADLNDP9zYzG6Q at mail.gmail.com>
>>>> Content-Type: text/plain; charset="utf-8"
>>>>
>>>> Dear Gate users and developers,
>>>>
>>>> There are a couple of papers [1
>>>> <https://aapm.onlinelibrary.wiley.com/doi/abs/10.1118/1.4824694>,2
>>>> <https://ieeexplore.ieee.org/document/5751205>] addressing the
>>>> importance
>>>> of adding the simulation of Lu-176 in Lutetium based crystal in GATE
>>>> simulation. I try to do this to my simulated PET system that has
>>>> thousands
>>>> of pieces of crystals (created with linear and cubic array repeater). My
>>>> general idea of implementing this is to create a Lu176 ion source and
>>>> then
>>>> attach it to my crystals. However,  when I do:
>>>>
>>>> /gate/source/Lu176/attachTo Crystal
>>>>
>>>> the Lu176 is only attached to a single piece of crystal (which can be
>>>> visualized with /gate/source/Lu176/visualize 1000 red 3).  Has anyone
>>>> implemented this before? Could you please share your thoughts?
>>>>
>>>> Thanks a lot. Greatly appreciated.
>>>>
>>>> Zhengzhi
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