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Home > Archive > Radiology > December 2005 > How to Convert Image pixel intensity to Hounsfield Unit.
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| Author |
How to Convert Image pixel intensity to Hounsfield Unit.
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| dqchen 2005-11-12, 6:06 pm |
| I am just using Colon CT slice. Now I have the image pixel intensity
(0~2469), rescale slope (1), and rescale intercept (-1024).
The rescale slope and intercept are known from the DiCom Header.
Then if I use the common relationship between pixel intensity, say X
and Hounsfield Unit (HU), say Y: Y=x*slope+intercept, I get the HU
for air is 1024. It is obviously wrong. So, I suspect the
relationship equation above be wrong. Any one can help to confirm?
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| Ted Wu, PhD 2005-12-01, 5:59 pm |
| The formula is correct but you calculated wrong. Note the intercept
is -1024.
So for the air, the HU = 0*1 - 1024 = -1024 (HU), not 1024.
______________________________________________________________
Y. Ted Wu, Ph.D. Able Software Corp. http://www.3d-doctor.com
3D-DOCTOR: The Vector-Based 3D Modeling, Imaging and Measurement Software
______________________________________________________________
"dqchen" <dqchentju@yahoo-dot-com.no-spam.invalid> wrote in message
news:GbadnSR3-dtuVPLeRVn_vQ@giganews.com...
> I am just using Colon CT slice. Now I have the image pixel intensity
> (0~2469), rescale slope (1), and rescale intercept (-1024).
>
> The rescale slope and intercept are known from the DiCom Header.
>
>
> Then if I use the common relationship between pixel intensity, say X
> and Hounsfield Unit (HU), say Y: Y=x*slope+intercept, I get the HU
> for air is 1024. It is obviously wrong. So, I suspect the
> relationship equation above be wrong. Any one can help to confirm?
>
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