# PSF+TOF reconstruction error **URL:** \ **Category:** General Discussions\ **Created:** [September 15, 2020, 10:05am UTC](https://castor-project.discourse.group/t/psf-tof-reconstruction-error/172 "2020-09-15T10:05:00Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![Hadi\_Rezaei](https://avatars.discourse-cdn.com/v4/letter/h/ebca7d/32.png) [@Hadi\_Rezaei](https://castor-project.discourse.group/u/Hadi_Rezaei)\ **Post date:** [September 15, 2020, 10:05am UTC](https://castor-project.discourse.group/t/psf-tof-reconstruction-error/172/1 "2020-09-15T10:05:00Z")
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 ---
**Author:** ![FILIPOVIC\_PIERUCCI\_M](https://avatars.discourse-cdn.com/v4/letter/f/8491ac/32.png) [@FILIPOVIC\_PIERUCCI\_M](https://castor-project.discourse.group/u/FILIPOVIC_PIERUCCI_M)\ **Post date:** [September 15, 2020, 10:16am UTC](https://castor-project.discourse.group/t/psf-tof-reconstruction-error/172/2 "2020-09-15T10:16:16Z")
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 ---
**Author:** ![Hadi\_Rezaei](https://avatars.discourse-cdn.com/v4/letter/h/ebca7d/32.png) [@Hadi\_Rezaei](https://castor-project.discourse.group/u/Hadi_Rezaei)\ **Post date:** [September 15, 2020, 2:29pm UTC](https://castor-project.discourse.group/t/psf-tof-reconstruction-error/172/3 "2020-09-15T14:29:26Z")
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 ---
**Author:** ![FILIPOVIC\_PIERUCCI\_M](https://avatars.discourse-cdn.com/v4/letter/f/8491ac/32.png) [@FILIPOVIC\_PIERUCCI\_M](https://castor-project.discourse.group/u/FILIPOVIC_PIERUCCI_M)\ **Post date:** [September 15, 2020, 2:51pm UTC](https://castor-project.discourse.group/t/psf-tof-reconstruction-error/172/4 "2020-09-15T14:51:41Z")
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? ---
**Author:** ![Hadi\_Rezaei](https://avatars.discourse-cdn.com/v4/letter/h/ebca7d/32.png) [@Hadi\_Rezaei](https://castor-project.discourse.group/u/Hadi_Rezaei)\ **Post date:** [September 15, 2020, 3:57pm UTC](https://castor-project.discourse.group/t/psf-tof-reconstruction-error/172/5 "2020-09-15T15:57:23Z")
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 1. 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 ---
**Author:** ![Hadi\_Rezaei](https://avatars.discourse-cdn.com/v4/letter/h/ebca7d/32.png) [@Hadi\_Rezaei](https://castor-project.discourse.group/u/Hadi_Rezaei)\ **Post date:** [September 16, 2020, 4:40am UTC](https://castor-project.discourse.group/t/psf-tof-reconstruction-error/172/6 "2020-09-16T04:40:22Z")
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 ---
**Author:** ![FILIPOVIC\_PIERUCCI\_M](https://avatars.discourse-cdn.com/v4/letter/f/8491ac/32.png) [@FILIPOVIC\_PIERUCCI\_M](https://castor-project.discourse.group/u/FILIPOVIC_PIERUCCI_M)\ **Post date:** [September 16, 2020, 8:22am UTC](https://castor-project.discourse.group/t/psf-tof-reconstruction-error/172/7 "2020-09-16T08:22:55Z")
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