[Gate-users] About ASCCI Singles output

[Marc Chamberland]

Hi Gergely,

Thanks for bringing this up to other users' attention! I did not know about this error in the documentation. I'll see if I can fix the user's guide for version 6.2.

Cheers!
Marc



__________________________

Marc Chamberland, MSc
PhD candidate
Department of Physics
Carleton University
Ottawa (ON)

On 2012-12-07, at 8:36 AM, Patay Gergely <patay.gergely at mediso.hu<mailto:patay.gergely at mediso.hu>> wrote:

Dear Gaters,

in the ascii output, the columns described as 'XYZ position of the annihilation' do *not* contain the annihilation coordinates, instead, they are
the XYZ position of the *radioactive decay* which produced the soon-to-be-annihilated positron (or, in the case of back-to-back source, the origin of the gamma pair).

This is a rather misleading error in the documentation which survives in the new revisions (at least from v3.1 to v6.2, maybe earlier too). The correct label should be 'XYZ position of the source' or something like this.

If you really want to access the actual annihilation coordinates, you either have to modify the corresponding source code of Gate, or jump directly into the raw Geant4 track dump (enabled by /tracking/verbose 2 ).

cheers,
Gergely

-----
Gergely PATAY
 Mediso Ltd.



On 2012-12-07 13:37, Marc Chamberland wrote:
Some answers:

1) This is the position of the positron-electron annihilation, not the position
of the interaction within the crystal. It makes sense that it occurs very near
your source.

2) I don't know. Singles are what you get after the digitizer processes your
hits. They should be in your crystal.

3) I don't know.

4) The volume IDs  are exactly what the name says: the ID (identification
number) of the volume in which the hit (or single) occurred. Each volume in
each level of the hierarchy of the system you're using (e.g. base, rsector,
module, etc.) gets a unique ID number. The volumes get numbered sequentially. If
you use a cubic array repeater, then the volumes are numbered 0 to N-1 (where N
is the number of volumes you have in your array) and they increase first along
the x axis, then along y, then along z. For a ring repeater, they increase in
the counterclockwise direction, if I remember correctly.

Hope this helps!
Marc



__________________________

Marc Chamberland, MSc
PhD candidate
Department of Physics
Carleton University
Ottawa (ON)


On 2012-12-07, at 5:33 AM, open researcher <openresearcher90 at gmail.com<mailto:openresearcher90 at gmail.com>
<mailto:openresearcher90 at gmail.com>>
 wrote:

I want some clarifications regarding the output of Singles output -
1. What does XYZ position of the annihilation in world referential mean. (I
have defined a source at 0, -22, 0 cms (and y axis is depth axis) and a NaI
crystal at -15 cm. Singles file has readings like 0.000e+00 -2.200e+02
0.000e+00 since the interaction is happening in the crystal I think the
y-coordinate must be -15 cm I don't know how it is showing the coordinate of
the source)
2. XYZ position of the single in the world referential shows (0, 1, 0) for
some singles, (0, 2, 0) for some and (0, 0, 0) for some singles. what can I
infer from this ?
3. for some Singles time stamp is -ve  (what can it mean ?)
4. what are Volume IDs ?
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