# Latest **URL:** https://castor-project.discourse.group/latest.md [Latest](https://castor-project.discourse.group/latest.md) · [Categories](https://castor-project.discourse.group/categories.md) · [Tags](https://castor-project.discourse.group/tags.md) --- ## [Welcome to Discourse](https://castor-project.discourse.group/t/welcome-to-discourse/7)
**Author:** [@system](https://castor-project.discourse.group/u/system)\ **Replies:** 0\ **Last updated:** [June 7, 2022, 2:14pm UTC](https://castor-project.discourse.group/t/welcome-to-discourse/7 "2022-06-07T14:14:23Z")
Welcome to the CASToR discourse forum. This board gather Q&A regarding the use of the CASToR platform, documentation and issues workarounds. --- ## [Systematic over-correction with scatter correction in TOF list-mode reconstruction](https://castor-project.discourse.group/t/systematic-over-correction-with-scatter-correction-in-tof-list-mode-reconstruction/1501)
**Author:** [@D.Liang](https://castor-project.discourse.group/u/D.Liang)\ **Replies:** 0\ **Last updated:** [September 18, 2026, 8:31am UTC](https://castor-project.discourse.group/t/systematic-over-correction-with-scatter-correction-in-tof-list-mode-reconstruction/1501 "2026-09-18T08:31:13Z")
Dear CASToR developers and users, I am experiencing a systematic apparent over-correction when applying scatter correction in TOF list-mode PET reconstruction with CASToR. I have already checked several common causes di… --- ## [Questions on Normalization Factor Calculation (Annular Phantom Chord Length & Attenuation) & Reconstruction Speed (List-mode vs. Histogram) for Dedicated Brain PET](https://castor-project.discourse.group/t/questions-on-normalization-factor-calculation-annular-phantom-chord-length-attenuation-reconstruction-speed-list-mode-vs-histogram-for-dedicated-brain-pet/1498)
**Author:** [@zzp](https://castor-project.discourse.group/u/zzp)\ **Replies:** 1\ **Last updated:** [September 17, 2026, 5:21pm UTC](https://castor-project.discourse.group/t/questions-on-normalization-factor-calculation-annular-phantom-chord-length-attenuation-reconstruction-speed-list-mode-vs-histogram-for-dedicated-brain-pet/1498 "2026-09-17T17:21:51Z")
Dear CASToR Team and Community, First of all, thank you very much for developing and maintaining this comprehensive open-source reconstruction framework. I am an R&D engineer working on a dedicated brain PET scanner. W… --- ## [Question: Understanding scatter correction in CASToR — why are pre- and post-scatter-correction images nearly identical?](https://castor-project.discourse.group/t/question-understanding-scatter-correction-in-castor-why-are-pre-and-post-scatter-correction-images-nearly-identical/1492)
**Author:** [@bgyamfi1](https://castor-project.discourse.group/u/bgyamfi1)\ **Replies:** 3\ **Last updated:** [September 10, 2026, 7:28am UTC](https://castor-project.discourse.group/t/question-understanding-scatter-correction-in-castor-why-are-pre-and-post-scatter-correction-images-nearly-identical/1492 "2026-09-10T07:28:56Z")
Hi everyone, I am trying to better understand how scatter correction is implemented in CASToR, particularly how the estimated scatter contribution is incorporated into the PET reconstruction. In our reconstruction work… --- ## [Question about iOptimizerSens availability in CASToR 3.2.1 for custom PET list-mode sensitivity calculation](https://castor-project.discourse.group/t/question-about-ioptimizersens-availability-in-castor-3-2-1-for-custom-pet-list-mode-sensitivity-calculation/1475)
**Author:** [@Hiroaki\_Sagara](https://castor-project.discourse.group/u/Hiroaki_Sagara)\ **Replies:** 1\ **Last updated:** [September 8, 2026, 7:42pm UTC](https://castor-project.discourse.group/t/question-about-ioptimizersens-availability-in-castor-3-2-1-for-custom-pet-list-mode-sensitivity-calculation/1475 "2026-09-08T19:42:11Z")
Dear CASToR developers, I am developing a reproducible PET Monte Carlo and list-mode reconstruction workflow using OpenGATE 10.1.1 and CASToR 3.2.1. The scanner is described by a custom CASToR LUT and contains 60,800 … --- ## [Access Violation Error in smc2castor](https://castor-project.discourse.group/t/access-violation-error-in-smc2castor/1438)
**Author:** [@Sajad](https://castor-project.discourse.group/u/Sajad)\ **Replies:** 1\ **Last updated:** [June 10, 2026, 3:22pm UTC](https://castor-project.discourse.group/t/access-violation-error-in-smc2castor/1438 "2026-06-10T15:22:48Z")
Hello, I am trying to use smc2castor, but the program crashes with an “Access Violation” error during execution. System Information: Operating System: Windows (please specify version) CASToR Version: (please specify) … --- ## [3rd International Workshop on Machine Learning and Quantum Computing Applications in Medicine and Physics](https://castor-project.discourse.group/t/3rd-international-workshop-on-machine-learning-and-quantum-computing-applications-in-medicine-and-physics/1439)
**Author:** [@acoussat](https://castor-project.discourse.group/u/acoussat)\ **Replies:** 0\ **Last updated:** [June 8, 2026, 9:40am UTC](https://castor-project.discourse.group/t/3rd-international-workshop-on-machine-learning-and-quantum-computing-applications-in-medicine-and-physics/1439 "2026-06-08T09:40:07Z")
Dear CASToR users and developers, We cordially invite you to the 3rd International Workshop on Machine Learning and Quantum Computing Applications in Medicine and Physics, which will take place in Warsaw (Poland) from 7… --- ## [Castor instalation for dummies](https://castor-project.discourse.group/t/castor-instalation-for-dummies/1376)
**Author:** [@edermoraes](https://castor-project.discourse.group/u/edermoraes)\ **Replies:** 1\ **Last updated:** [April 9, 2026, 6:31am UTC](https://castor-project.discourse.group/t/castor-instalation-for-dummies/1376 "2026-04-09T06:31:48Z")
Please, we are needing some instructions to install Castor in the most lower level. We have tried either by makefile or cmake in a ubuntu 22.04.5 LTS 64 bits gnome 42.9 @ AMD® Ryzen 9 5950x 16-core processor × 32. Best… --- ## [Issue Downloading CASToR](https://castor-project.discourse.group/t/issue-downloading-castor/1346)
**Author:** [@rw565](https://castor-project.discourse.group/u/rw565)\ **Replies:** 5\ **Last updated:** [February 18, 2026, 3:15pm UTC](https://castor-project.discourse.group/t/issue-downloading-castor/1346 "2026-02-18T15:15:29Z")
Hi all, I’ve seen a few discussions about this in the past, but I couldn’t find one that detailed quite the same issue. I am trying to download CASToR from the website on Microsoft Edge, Chrome, and Firefox on two diffe… --- ## [Segmentation violation in castor-GATEMacToGeom for castor v3.2.1](https://castor-project.discourse.group/t/segmentation-violation-in-castor-gatemactogeom-for-castor-v3-2-1/1343)
**Author:** [@kochebina](https://castor-project.discourse.group/u/kochebina)\ **Replies:** 1\ **Last updated:** [February 4, 2026, 8:21pm UTC](https://castor-project.discourse.group/t/segmentation-violation-in-castor-gatemactogeom-for-castor-v3-2-1/1343 "2026-02-04T20:21:41Z")
Dear castor experts and developers, I have a Segmentation violation in castor-GATEMacToGeom for castor v3.2.1, compiled with root 6.32.02. Interestingly, the same exe in the same configuration works fine in castor v.3.1… --- ## [Ring articact in SPECT reconstruction](https://castor-project.discourse.group/t/ring-articact-in-spect-reconstruction/1328)
**Author:** [@savvidis](https://castor-project.discourse.group/u/savvidis)\ **Replies:** 1\ **Last updated:** [January 15, 2026, 8:32pm UTC](https://castor-project.discourse.group/t/ring-articact-in-spect-reconstruction/1328 "2026-01-15T20:32:06Z")
Dear Castor users, I am trying to reconstruct simulated data of SPECT system of two heads. During the reconstruction process, I observe: with low-statistics data the reconstructed images appear as expected. with highe… --- ## [Issue where implementing TOF creates extremely large numbers for crystal ID out of scanner range](https://castor-project.discourse.group/t/issue-where-implementing-tof-creates-extremely-large-numbers-for-crystal-id-out-of-scanner-range/1292)
**Author:** [@Burgeon](https://castor-project.discourse.group/u/Burgeon)\ **Replies:** 5\ **Last updated:** [December 15, 2025, 9:16am UTC](https://castor-project.discourse.group/t/issue-where-implementing-tof-creates-extremely-large-numbers-for-crystal-id-out-of-scanner-range/1292 "2025-12-15T09:16:43Z")
Im reconstructing PET scanner data, and I’ve had it working without incorporating TOF information into my data for a while. Now I want to use TOF data, but it creates a lot of errors like this: \*\*\*\*\* iScannerPET::GetPo… --- ## [How to get the the output of objective function or Likelyhood function?](https://castor-project.discourse.group/t/how-to-get-the-the-output-of-objective-function-or-likelyhood-function/1261)
**Author:** [@boli](https://castor-project.discourse.group/u/boli)\ **Replies:** 3\ **Last updated:** [November 13, 2025, 9:04am UTC](https://castor-project.discourse.group/t/how-to-get-the-the-output-of-objective-function-or-likelyhood-function/1261 "2025-11-13T09:04:34Z")
Dear respected expert, I have just started using castoR for PET imaging research and would like to ask whether it is possible to output the objective function value or the likelihood probability value during each iterat… --- ## [Empy cdh after converting pixelated camera Root file from GATE 8.2](https://castor-project.discourse.group/t/empy-cdh-after-converting-pixelated-camera-root-file-from-gate-8-2/1117)
**Author:** [@Sharareh](https://castor-project.discourse.group/u/Sharareh)\ **Replies:** 14\ **Last updated:** [November 4, 2025, 10:39am UTC](https://castor-project.discourse.group/t/empy-cdh-after-converting-pixelated-camera-root-file-from-gate-8-2/1117 "2025-11-04T10:39:52Z")
Hello CASToR team, I’m encountering an issue when converting GATE simulation ROOT files to CDH format for a pixelated camera. After running the conversion, the output CDH file appears empty. My key question is: Does CAS… --- ## [SPECT castor-GATERootToCastor segmentation violation](https://castor-project.discourse.group/t/spect-castor-gateroottocastor-segmentation-violation/547)
**Author:** [@Han\_Zhao](https://castor-project.discourse.group/u/Han_Zhao)\ **Replies:** 1\ **Last updated:** [October 20, 2025, 12:37pm UTC](https://castor-project.discourse.group/t/spect-castor-gateroottocastor-segmentation-violation/547 "2025-10-20T12:37:06Z")
Dear CASToR users, I’m trying to convert the .root file from the GATE simulation to castor’s castor-GATERootToCastor program .Cdf file, for monolithic crystals I can easily achieve data conversion, but for pixelated cry… --- ## [Problem running GATERootToCastor](https://castor-project.discourse.group/t/problem-running-gateroottocastor/896)
**Author:** [@imbeatrizp](https://castor-project.discourse.group/u/imbeatrizp)\ **Replies:** 4\ **Last updated:** [October 20, 2025, 9:40am UTC](https://castor-project.discourse.group/t/problem-running-gateroottocastor/896 "2025-10-20T09:40:26Z")
Hi everyone! I am trying to reconstruct an output of a voxelised simulation in a PET/CT system resulted from GATE. I started by applying castor-GATEMacToGeom to generate a geom file from my scanner GE D690 compatible w… --- ## [Scatter and randoms correction on CASToR using ROOT files from GATE](https://castor-project.discourse.group/t/scatter-and-randoms-correction-on-castor-using-root-files-from-gate/1220)
**Author:** [@imbeatrizp](https://castor-project.discourse.group/u/imbeatrizp)\ **Replies:** 2\ **Last updated:** [October 17, 2025, 4:13pm UTC](https://castor-project.discourse.group/t/scatter-and-randoms-correction-on-castor-using-root-files-from-gate/1220 "2025-10-17T16:13:12Z")
Hi everyone, I have read some previous topics here in the forum about the topic of Randoms and Scatter corrections that say CASToR can’t directly compute them. I am using ROOT files from GATE PET simulation, and I woul… --- ## [4th ETSI Hackathon At Chiba, Japan (Nov 9th-10th, 2025)](https://castor-project.discourse.group/t/4th-etsi-hackathon-at-chiba-japan-nov-9th-10th-2025/1151)
**Author:** [@Maxime\_Toussaint](https://castor-project.discourse.group/u/Maxime_Toussaint)\ **Replies:** 1\ **Last updated:** [October 15, 2025, 11:11am UTC](https://castor-project.discourse.group/t/4th-etsi-hackathon-at-chiba-japan-nov-9th-10th-2025/1151 "2025-10-15T11:11:10Z")
Copy/pasta of an invitation made by the ETSI organizer. ———————————————————————————- Dear all We’re inviting you to join us for the 4th Hackathon from the Emission Tomography Standardization Initiative to help establi… --- ## [Download failed](https://castor-project.discourse.group/t/download-failed/1222)
**Author:** [@zhichao](https://castor-project.discourse.group/u/zhichao)\ **Replies:** 2\ **Last updated:** [October 13, 2025, 9:44am UTC](https://castor-project.discourse.group/t/download-failed/1222 "2025-10-13T09:44:51Z")
I cant download CASToR from the site: https://castor-project.org/download. --- ## [Twice attenuation correction for randoms and scatter correction factors?](https://castor-project.discourse.group/t/twice-attenuation-correction-for-randoms-and-scatter-correction-factors/1189)
**Author:** [@seanlam](https://castor-project.discourse.group/u/seanlam)\ **Replies:** 0\ **Last updated:** [September 12, 2025, 9:44am UTC](https://castor-project.discourse.group/t/twice-attenuation-correction-for-randoms-and-scatter-correction-factors/1189 "2025-09-12T09:44:45Z")
Dear developer Recently, some strange things have happened during my reconstruction attempts. In my understanding, With ac factor and norm factor in both CDF and Normalization file is the right way to reconstruct pet i… --- ## [Artefact at the edge of the FOV](https://castor-project.discourse.group/t/artefact-at-the-edge-of-the-fov/1181)
**Author:** [@s\_mousavi](https://castor-project.discourse.group/u/s_mousavi)\ **Replies:** 1\ **Last updated:** [September 9, 2025, 8:18am UTC](https://castor-project.discourse.group/t/artefact-at-the-edge-of-the-fov/1181 "2025-09-09T08:18:32Z")
Hello All, I have reconstructed a the image of a cylindrical phantom using CASToR using the following cases: With normalization: a. List-mode data b. Histogram mode data Without normalization: a. List-mode data b.… --- ## [forward projection](https://castor-project.discourse.group/t/forward-projection/216)
**Author:** [@Hadi\_Rezaei](https://castor-project.discourse.group/u/Hadi_Rezaei)\ **Replies:** 10\ **Last updated:** [September 8, 2025, 6:48pm UTC](https://castor-project.discourse.group/t/forward-projection/216 "2025-09-08T18:48:23Z")
Dear CASTOR users and developers I need to forward project an image and I reed a previous email in the castor mailing list that there is a piece of code for this process. Does anyone work with this code and is it possib… --- ## [Reconstruction for a pinhole camera](https://castor-project.discourse.group/t/reconstruction-for-a-pinhole-camera/1161)
**Author:** [@Sharareh](https://castor-project.discourse.group/u/Sharareh)\ **Replies:** 2\ **Last updated:** [September 2, 2025, 11:47am UTC](https://castor-project.discourse.group/t/reconstruction-for-a-pinhole-camera/1161 "2025-09-02T11:47:44Z")
Hello, Is it possible to perform reconstruction for a pinhole camera in CASToR? Could you please provide guidance on how to do it? Thanks --- ## [CT reconstruction and blank measurements](https://castor-project.discourse.group/t/ct-reconstruction-and-blank-measurements/779)
**Author:** [@savvidis](https://castor-project.discourse.group/u/savvidis)\ **Replies:** 4\ **Last updated:** [August 20, 2025, 1:10pm UTC](https://castor-project.discourse.group/t/ct-reconstruction-and-blank-measurements/779 "2025-08-20T13:10:49Z")
Dear Castor users, I am working on CT reconstruction with Castor using GATE simulations, and I would like to incorporate the blank measurements in my .cdf file. I have the projections for each angle (with my phantom) an… --- ## [Amide template + python code to simplify the analysis of the NEMA NU4 Image Quality phantom](https://castor-project.discourse.group/t/amide-template-python-code-to-simplify-the-analysis-of-the-nema-nu4-image-quality-phantom/1149)
**Author:** [@Maxime\_Toussaint](https://castor-project.discourse.group/u/Maxime_Toussaint)\ **Replies:** 0\ **Last updated:** [August 18, 2025, 7:45pm UTC](https://castor-project.discourse.group/t/amide-template-python-code-to-simplify-the-analysis-of-the-nema-nu4-image-quality-phantom/1149 "2025-08-18T19:45:25Z")
Me and two of my colleagues recently made public on github a tool to make the analysis of the NEMA NU4 Image Quality phantom easier, see \[1\]. It consists of an Amide template and a python script. The Amide template incl… --- ## [Pixelated camera reconstruction in CASToR](https://castor-project.discourse.group/t/pixelated-camera-reconstruction-in-castor/1146)
**Author:** [@Sharareh](https://castor-project.discourse.group/u/Sharareh)\ **Replies:** 0\ **Last updated:** [August 14, 2025, 7:08pm UTC](https://castor-project.discourse.group/t/pixelated-camera-reconstruction-in-castor/1146 "2025-08-14T19:08:30Z")
Hello I am using a 40 × 9 pixelated gamma camera in castOR. Large pixels reduce resolution and create artifacts. sp\_bins works for uniform detectors but not for pixelated ones. What approach would you recommend to impr… --- ## [Python code for evaluating resolvability of sectors in a Hot Spot phantom](https://castor-project.discourse.group/t/python-code-for-evaluating-resolvability-of-sectors-in-a-hot-spot-phantom/679)
**Author:** [@Maxime\_Toussaint](https://castor-project.discourse.group/u/Maxime_Toussaint)\ **Replies:** 1\ **Last updated:** [August 13, 2025, 8:25pm UTC](https://castor-project.discourse.group/t/python-code-for-evaluating-resolvability-of-sectors-in-a-hot-spot-phantom/679 "2025-08-13T20:25:33Z")
Greetings, As presented in \[1\], the NEMA NU 4 standard is not perfect. Here, I discuss about the recommendation of \[1\] for PET spatial resolution. Currently, the NEMA standard proposes to use a point source that is reco… --- ## [Get the sinogram from .cdf and .cdh](https://castor-project.discourse.group/t/get-the-sinogram-from-cdf-and-cdh/1140)
**Author:** [@Sharareh](https://castor-project.discourse.group/u/Sharareh)\ **Replies:** 1\ **Last updated:** [August 8, 2025, 4:54pm UTC](https://castor-project.discourse.group/t/get-the-sinogram-from-cdf-and-cdh/1140 "2025-08-08T16:54:01Z")
Hi How to get the sinogram from .cdf and .cdh CASToR output files. Is there any code that can read CASToR data format and create the sinograms? Best regards, Sharareh --- ## [Reconstructed image in CASToR consistently looked like the sensitivity map](https://castor-project.discourse.group/t/reconstructed-image-in-castor-consistently-looked-like-the-sensitivity-map/1130)
**Author:** [@satyamtiwari](https://castor-project.discourse.group/u/satyamtiwari)\ **Replies:** 1\ **Last updated:** [August 8, 2025, 11:38am UTC](https://castor-project.discourse.group/t/reconstructed-image-in-castor-consistently-looked-like-the-sensitivity-map/1130 "2025-08-08T11:38:00Z")
My objective has been to take the ROOT output from my GATE simulation and successfully reconstruct an image of my source using CASToR’s MLEM algorithm. From the very beginning, I’ve had one consistent problem: the fi… --- ## [Histogram Input Datafile Generation](https://castor-project.discourse.group/t/histogram-input-datafile-generation/1081)
**Author:** [@s\_mousavi](https://castor-project.discourse.group/u/s_mousavi)\ **Replies:** 5\ **Last updated:** [July 23, 2025, 7:21am UTC](https://castor-project.discourse.group/t/histogram-input-datafile-generation/1081 "2025-07-23T07:21:16Z")
Hello All, I want to create a histogram input datafile. However, I have a couple of ambiguities in understanding histogram mode. 1- In table 2, page 34 of the documentation, what is “Amount of data in the histogram (TO… [Next page](https://castor-project.discourse.group/latest.md?page=1)