# SPECT quantification issue

**URL:** <https://discourse.slicer.org/t/spect-quantification-issue/37273>\
**Category:** Support\
**Created:** [July 9, 2024, 7:56am UTC](https://discourse.slicer.org/t/spect-quantification-issue/37273 "2024-07-09T07:56:09Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Jan\_Lennart](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/jan_lennart/32/15701_2.png) [@Jan\_Lennart](https://discourse.slicer.org/u/Jan_Lennart)\
**Post date:** [July 9, 2024, 7:56am UTC](https://discourse.slicer.org/t/spect-quantification-issue/37273/1 "2024-07-09T07:56:09Z")

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Hi Slicer Users,

I desperately need some help here. I would like to quantify a few SPECT images and wanted to calculate the calibration factor of a the protocol/camera by looking at a phantom scan.

When I place a few segments in the phantom (outside the hotter spheres) I get values of around 6000-6700 counts. In other programs like VivoQuant or Hermes Affinity, the results are more like 3500 counts.

Does anybody know why there is this discrepancy?

Thank you so much,  
Jan

 ![image](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/6/1/6138a40f9d64216c01394a862a647c9657cdff50.png)

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**Author:** ![MAY](https://avatars.discourse-cdn.com/v4/letter/m/58f4c7/32.png) [@MAY](https://discourse.slicer.org/u/MAY)\
**Post date:** [July 24, 2024, 8:24am UTC](https://discourse.slicer.org/t/spect-quantification-issue/37273/2 "2024-07-24T08:24:25Z")

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Hello, I would like to ask you, how do you get these counts? What plug-ins are used? I would appreciate it if you could provide me with this information.

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**Author:** ![Jan\_Lennart](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/jan_lennart/32/15701_2.png) [@Jan\_Lennart](https://discourse.slicer.org/u/Jan_Lennart)\
**Post date:** [July 24, 2024, 8:34am UTC](https://discourse.slicer.org/t/spect-quantification-issue/37273/3 "2024-07-24T08:34:37Z")

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this was done with the module “segment statistics” (no plug in was used)

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**Author:** ![MAY](https://avatars.discourse-cdn.com/v4/letter/m/58f4c7/32.png) [@MAY](https://discourse.slicer.org/u/MAY)\
**Post date:** [July 25, 2024, 3:37pm UTC](https://discourse.slicer.org/t/spect-quantification-issue/37273/4 "2024-07-25T15:37:48Z")

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Thank you very much. I have another question. Do you know the meanings of mean, voxel count (LM) and voxel count (SV) respectively in the picture?

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**Author:** ![akmal871026](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/akmal871026/32/11642_2.png) [@akmal871026](https://discourse.slicer.org/u/akmal871026)\
**Post date:** [September 5, 2024, 1:57am UTC](https://discourse.slicer.org/t/spect-quantification-issue/37273/5 "2024-09-05T01:57:38Z")

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Dear @Jan_Lennart ,

In segment statistics, It just gave you the mean count in the segment. If you want to know total counts of your segments, you have to multiply mean count with voxel counts. Then you will get the total counts.

6000-6700 counts as you mentioned is what? mean? or min? or total?

then 3500 counts using Hermes is what? mean? or min? or total?