[Gate-users] minSectorDifference

[Marcin Balcerzyk]

Hi,

minSectorDifference is described in section 8.4.2 of Users Guide. It is not
very clear, I agree. 

Imagine, you have a PET scanner with 12 detectors on a ring, numbered like a
clock. minSectorDifference=3 would mean that only coincidences from pairs of
detectors 1-4, 2-5, 1-5,1-6,1-7, 1-8, 1-9,1-10 etc. but not 1-1, 1-2, 1-11,
1-12 etc. would be accepted as valid coincidences.  That means that only no-
or weakly scattered photons can form valid coincidences. 

I checked once for some phantom and PET ring and minSectorDifference=3 -
about 25% of coincidences were from close detectors i.e.
minSectorDifference<3.

Marcin Balcerzyk
Univesrsidad Complutense de Madrid
 
Message: 3
Date: Mon, 17 Mar 2008 11:00:42 +0800
From: "jinxia guo" <babygjx at gmail.com>
Subject: [Gate-users] what does the 'min Sector Difference' mean?
To: gate-users at lists.healthgrid.org
Message-ID:
	<2bcf96900803162000g568d2743m21793309d6955669 at mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"

Dear Gaters,

I have one question when I set the digitizer parameters.

In the command  "/gate/digitizer/Coincidences/minSectorDifference <number>",
I am puzzled about the parameter

" minimum sector difference", I want to know its meaning in reality and how
it influences the performance of the

circuit?

Dose anyone help to explain it ?

Thanks in before hand!