Dear CASToR users
I used TOF + psf for reconstruction a Derenzo phantom but I found this warning.
"Warning: quantization TOF bin size wrong or not provided, so switching to TOF list-mode reconstruction which neglects the quantization TOF bin size!"
Does it mean that I can not use psf and TOF together in CASTOR?? I need to investigate PSF+TOF. How can I do it??
Any help would be appreciated.
Best
Hadi
Hi Hadi,
This warning should be related only to TOF, not to the use of PSF. It says that your input datafile implies that your scanner has an (almost) infinite precision for TOF measurements. If this is the case everything’s ok, otherwise if your scanner quantizes TOF measurements, you should provide the quantization bin or step it in the datafile header (.cdh).
All of this won’t really make a difference for the reconstructed image, unless the quantization of the TOF measurements is very rough, which is probably not the case for your scanner.
Is the reconstructed image OK?
Best
Marina
Hi Marina
Thank you for responding
My reconstructed image is Ok and when I imply only TOF (not PSF) I don’t see this warning and the TOF bin is provided in .cdh file however the different TOF values don’t make a difference in image quality. Is this an issue in the reconstruction process or it is normal?
Thank you
Best
Hai
Strange, which version of CASToR do you use? What is the size of the list mode TOF quantization bin and what do you mean by different TOF values, different values of the TOF quantization bin size? Do you add this info in the .cdh yourself or do you rely on the GATE to CASToR converter?
I use castor_v3.0.1. Two of the content of my .cdh files are below:
1)
Data filename: miniderenzo420ring0.6sTOF_df.Cdf
Number of events: 46858725
Data mode: list-mode
Data type: PET
Start time (s): 0
Duration (s): 0.6
Scanner name: miniderenzo420ring0.6sTOF
Calibration factor: 1
Isotope: unknown
TOF information flag: 1
TOF resolution (ps): 430
List TOF measurement range (ps): 5753.19
Coincidence kind flag: 1
Maximum axial difference mm: 1200
Data filename: miniderenzo336ring0.6sTOF350_df.Cdf
Number of events: 42513982
Data mode: list-mode
Data type: PET
Start time (s): 0
Duration (s): 0.6
Scanner name: miniderenzo336ring0.6sTOF350
Calibration factor: 1
Isotope: unknown
TOF information flag: 1
TOF resolution (ps): 350
List TOF measurement range (ps): 4800
Coincidence kind flag: 1
Maximum axial difference mm: 960
Hi marina and other castor users
Should I change or add TOF information in .cdh file manually to see the effect of TOF variations?
As I mentioned in the previous emails when I use “-TOF reso” command on castor-GATERootToCastor I see the warning:" quantization TOF bin size wrong or not provided, so switching to TOF list-mode reconstruction which neglects the quantization TOF bin size!" on the reconstruction process. In previous email I sent two of the content of the .cdh files.
Thank you so much for your help
Best
Hadi
Hi,
Ok so in your datafile header you don’t specify the field I was talking about, the list mode TOF quantization bin size. You are talking about the field TOF resolution. So I would say everything’s OK, don’t worry about that warning, it’s a detail not worth caring about. If you still want to understand the warning you can look into the documentation and into our paper on TOF, “Time-of-flight (TOF) implementation for PET reconstruction in practice”.
Best
Marina