# Data type for PET and MR image

**URL:** https://discourse.itk.org/t/data-type-for-pet-and-mr-image/1468
**Category:** Beginner Questions
**Created:** [December 11, 2018, 1:06am UTC](https://discourse.itk.org/t/data-type-for-pet-and-mr-image/1468 "2018-12-11T01:06:11Z")
**Posts on this page:** 3
**Page:** 1

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### Author: ![zhuangming.shen](https://discourse.itk.org/letter_avatar_proxy/v4/letter/z/4af34b/32.png) [@zhuangming.shen](https://discourse.itk.org/u/zhuangming.shen)
#### Post date: [December 11, 2018, 1:06am UTC](https://discourse.itk.org/t/data-type-for-pet-and-mr-image/1468/1 "2018-12-11T01:06:11Z")

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Hi all,

I know “signed short” is usually assigned for a CT image in ITK because it’s voxel values are 16 bits integers. But how about PET image and MR image, should I also use “signed short” for them? Or use “float” instead? Any comments are welcomed.

Regards,

Zhuangming Shen

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### Author: ![dzenanz](https://discourse.itk.org/user_avatar/discourse.itk.org/dzenanz/32/1093_2.png) [@dzenanz](https://discourse.itk.org/u/dzenanz)
#### Post date: [December 11, 2018, 3:41pm UTC](https://discourse.itk.org/t/data-type-for-pet-and-mr-image/1468/2 "2018-12-11T15:41:26Z")

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For MRI, both `signed` and `unsigned` `short` are common. For PET, though, `float` and `double` are more frequent in my opinion.

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### Author: ![zhuangming.shen](https://discourse.itk.org/letter_avatar_proxy/v4/letter/z/4af34b/32.png) [@zhuangming.shen](https://discourse.itk.org/u/zhuangming.shen)
#### Post date: [December 12, 2018, 12:32am UTC](https://discourse.itk.org/t/data-type-for-pet-and-mr-image/1468/3 "2018-12-12T00:32:32Z")

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@dzenanz Thanks for your comments.