[gate-users] HR+

[Mutanga Theodore]

> Hi all,
>
> I do not know why, but the values listed in Table 3 of the PMB paper for
> the HR+ refer to the full-width at one tenth of the maximum and not at
> half-maximum !!!!
>

thanks for clarifying that, I was confused with these values.
I got the value for my simulation by using a 1mm diameter and 1mm lenght
cylindrical source in air (F 18 , activity 5.5MBq) and the the ECAT 962 in
GATE example. For reconstruction I used STIR FBP3DRP.I also tried matrix
sizes 144, 180 288 256.
 (I tried with FBP2D and OSMAPOSL but got worse resolution, I also used
Amide to draw the line profiles , there they use a Guassian fit instead
of a parabolic fit as stated in NEMA, shouldn't be very different ?)
I don't know do I have to correct for something before reconstruction ?

Could I please have the paper by S. Jan ?


My new simulation is as follows,

three sources F 18 located at  (source .6 diamter, .6 axial lenght)
sources are enclosed in glass capillaries .6mm inner radius ,1.4mm outer
radius and 1cm axial length.


(cm)
x=0 y=1  z=0
X=0 y=10
x=10 y=0

and
x=0 y=1  z=1/4FOV (3.875cm)
X=0 y=10
x=10 y=0

For 2D I dont know the usual septa configuration.but I placed the septa
inbetween each ring. I have to try that later.

I expect to get better results with these smaller source sizes. what do
you think ?

Cheers
Theodore


> Claude
>
> Mutanga Theodore wrote:
>
>> Hi and thanks for the information,
>>
>> I don't have access to Jan's article but it is quoted in another article
>> byt Jan et al , GATE : A Simulation Toolkit for PET and SPECT. Here he
>> has
>> got the resolution for the ECAT HR+ as
>>
>> radial at 10cm 11.8
>> tangential at 10cm 10.7
>>
>> However I cannot say my method has been good because in the first place
>> I
>> just simulated point sources in air, no casing, ( which is not true in
>> reality) I haven't corrected for anything ( NEMA didn't mention any
>> corrections though)??
>>
>> In another article published in EJNM and Molecular Imaging, Vol 30 N0 11
>> Nov 2003 the resolution of the ECAT HR+ is quoted as
>>
>> 2D axial at 0cm = 4.2mm
>>          at 10cm= 5.0mm
>>
>>    transaxial 1cm = 4.6
>>               10cm = 5.4mm
>>
>>
>> 3D axial at 0 cm 3.5 mm
>>             10cm = 5.3
>>     transaxial 1cm = 4.6mm
>>                 10cm = 5.4
>> I think NEMA 94 was used here , I haven't seen any data from using NEMA
>> 2001 maybe some has some references.
>>
>> If someone has S. Jans paper I would be happy to see it and replicate
>> his
>> methods.
>>
>>
>> Cheers
>>
>> Theodore
>>
>>
>>
>>
>>>>By the way I was simulating the ECAT exact hr+ and I would
>>>>like to compare my results with someone Here is what I had
>>>>for the resolution measurements , NEMA 2001 !
>>>>
>>>>transverse @ 1cm = 8.3 mm
>>>>axial @1 cm 11.5 mm
>>>>
>>>>
>>>>transverse radial @ 10cm = 10.59mm
>>>>transverse tangential@ 10cm = 10.66mm
>>>>
>>>>axial @10cm 10.31 mm
>>>>
>>>>
>>>Seems  way too low resolution to me. Should be about 5mm (measured).
>>>
>>>The 'old' NEMA HR+ reference is Brix et al, JNM 1996
>>>
>>>I believe Herzog, Tellman et al have a proc./paper with NEMA 2001
>>>measurements for 'four Siemens ECAT PET-scanners'.
>>>
>>>I thought Sebastien Jan has a paper on simulating HR+ with GATE.
>>>
>>>Kris
>>>
>>>
>>>PS: by the way: can we try to keep email subject lines relevant to the
>>>topic discussed?
>>>
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>>>
>>
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>
>
> --
> Claude Comtat					comtat at ieee.org
> Image acquisition and processing group		tel: +33 1 69 86 77 02
> Frédéric Joliot Hospital Facility		fax: +33 1 69 86 77 49
> French Atomic Energy Commission 		www-dsv.cea.fr/shfj
>
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