[Castor-users] Scatter rate estimation for LM-TOF-MLEM

[jbaran]

Hi Marina,

many thanks for your answer. could you please clarify what do you mean 
to "divide the estimated TOF bin scatter rates with the spatial width of 
the TOF bin, directly in the list-mode datafile". Once I estimate the 
scatter fraction I presume I should divide it by the TOF bin (e.g. 
200ps)? However, I do not specify the TOF bin size in my header. Unless 
the bin size is then defined as a TOF resolution?

Example of the header which I am using:

Data filename: data_df.Cdf
Number of events: 298175691
Data mode: list-mode
Data type: PET
Start time (s): 0
Duration (s): 500
Scanner name: scanner1
Calibration factor: 1
Isotope: unknown
TOF information flag: 1
TOF resolution (ps): 200
List TOF measurement range (ps): 3000
Scatter correction flag: 1

What is the way to proceed in that case?

All the best,
Jakub

On 2021-08-18 16:54, Marina Filipovic wrote:
> Hi Jacub,
> 
> Have you divided the estimated TOF bin scatter rates with the spatial
> width of the TOF bin, directly in the list-mode datafile, as explained
> in the documentation (general and TOF-specific) ?
> 
> Marina
> 
> On Wed, 18 Aug 2021, 00:52 jbaran, <jakub.baran at ifj.edu.pl> wrote:
> 
>> Dear Castor Developers and Users,
>> 
>> I am trying to incorporate the information about the scatter
>> correction
>> in LM-TOF-MLEM reconstruction. I have calculated the scatter
>> fraction
>> for each TOF bin. The values of scatter rate are in range 1-2. I
>> have
>> applied them for the reconstruction, however the reconstructed
>> images
>> seem to be not corrected for scatter. Please find the attached
>> screenshot. On the top panel, the reconstructed image with
>> true+scatter
>> coincidences is presented and on the bottom the same coincidences
>> were
>> used but with scatter correction applied. On the right corresponding
>> 
>> line profiles are presented (ots - no scatter correction; corrected1
>> -
>> scatter correction applied)
>> 
>> FYI: The total number of coincidences used for the reconstruction is
>> 1
>> order of magnitude lower than the number of possible LORs.
>> 
>> Do you have any idea what kind of values should be applied for the
>> scatter rate? Did you have any similar case and found the solution
>> how
>> the scatter rate should be calculated?
>> 
>> All the best,
>> Jakub
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