[Insight-users] DICOM WINDOW CENTER AND WIDTH

[Fleysher, Lazar]

Dear Roberto

I am not familiar with the meaning of "window center" and "window width" so cannot help you there, but as I mentined earlier, when two different acquisitions are made, you have to worry about other things.
You really have to know what your particular system does. there are other factors involved which may not be even stored in DICOM... :( These factors are receiver gain, some other scale factors which manufacturer decided to put in .... yes yes... You have to force the system to operate under identical conditions in two cases. Probably you did that, but I thought I would mention it anyway.

Lazar
________________________________
From: Roberto Laurita [roberto.laurita at gmail.com]
Sent: Thursday, December 29, 2011 07:30
To: Fleysher, Lazar
Cc: insight-users at itk.org
Subject: Re: [Insight-users] DICOM WINDOW CENTER AND WIDTH

Hi Lazar,

thank you for the answer.

It's better to supply more details. I have 1 slice acquired 2 times with a different TR. So I have 2 dicom files.
Reading the headers of these 2 files I found different values of "window center" and "window width". The MRI scanner provided 2 couples of values for rendering reason.

I'd like to know if it's possible to set "window center" and "window width" in the second file the same values of the first one. I need to compare the intensities (with different TR) of the same pixel

I thought about manual rescaling, but ...... if there is a better way ......

Thanks again

Ciao

Roberto


2011/12/29 Fleysher, Lazar <lazar.fleysher at mountsinai.org<mailto:lazar.fleysher at mountsinai.org>>
Hello Roberto

If I understood you correctly, you are asking how to convert from pixel intensity to image intensity.
This is done, as far as I know like this:

ImageValue = slope * storedValue + intercept.

However, you should be aware that this is not the whole story. Some other hardware-related
parameters might be at play which might contribute to scaling. It depends on how the data was acquired...

Lazar
________________________________________
From: insight-users-bounces at itk.org<mailto:insight-users-bounces at itk.org> [insight-users-bounces at itk.org<mailto:insight-users-bounces at itk.org>] on behalf of roberto.laurita [roberto.laurita at gmail.com<mailto:roberto.laurita at gmail.com>]
Sent: Wednesday, December 28, 2011 17:57
To: insight-users at itk.org<mailto:insight-users at itk.org>
Subject: [Insight-users] DICOM WINDOW CENTER AND WIDTH

Hi all,

I hope someone will help me. My deal is to import and compare 2 slices
(.dcm).

In Dicom header there are 2 parameters 0028|1050 and 0028|1051 which work
like contrast and brightness. I need to modify these parameters. Doing this,
pixel intensity should be modified.

Using ITK examples I'm able to do everything (read dicom header, and read
pixels) but the change above.

To compare pixel intensities of 2 slice windows center and width must be the
same. A normalization is required.

Could you suggest me how to change windows center and width ?

Thanks

BR

Roberto

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