Window Center / Window Width standard values

[martinrame]

Hi, I'm using dcmj2pnm to create jpeg images from Dicom files. If I use the +Wm parameter, in *most* cases the images are converted correctly, but some images appear too different from the rest (i.e.: too bright or too dark).

If I don't use the Wm parameter, and use +Ww instead, using the same values for ALL images, the images are converted ok.

My question is, is there a *standard* table of W/L values per modality?.

Thanks in advance.

[Jörg Riesmeier]

This will probably only work for CT since the pixel space is standardized (Hounsfield Units). In DICOMscope, we use the following presets:

Code: Select all

# ============================================================================
# VOI Window Level/Width Preset Definitions
[[VOI]]
# ============================================================================

# ----------------------------------------------------------------------------
# Assign a unique name to each preset and put this into the section name.
[CT_ABDOMEN]
# ----------------------------------------------------------------------------

# Description of the preset. Used in the GUI to present the selectable VOIs
description = Abdomen

# Modality to which this preset applies. Must be one of the DICOM defined
# terms for element (0008,0060) Modality, see PS3.3 C.7.3.1.1.1
modality = CT

# Window center
center = 45

# Window width
width = 250

[CT_BONE]
description = Bone
modality = CT
center = 500
width = 4000

[CT_CRANE]
description = Crane
modality = CT
center = 35
width = 100

[CT_LUNG]
description = Lung
modality = CT
center = -500
width = 2000

[CT_MEDIASTINUM]
description = Mediastinum
modality = CT
center = 45
width = 440

[CT_PELVIS]
description = Pelvis
modality = CT
center = 45
width = 300

Of course, each workstation vendor has its own (slightly deviating) presets ...

[nicolasdicom]

Hi Martin, Jörg,

I would like to share my point of view, becasue I had the same problem.

I found some Dicom images that doesn't have the window Center and Window width .
Tags:
0028 1050 Window Center
0028 1052 Window Width

More over , I found a particular problem in a PACS system. Some jpg thumbnails appeared in white color (too bright).

What have I done? as a test I put by hand these two tags, then I configured them with some values like a MG dicom files.

eg :
Window Center :2048
Window Width :4096
I know these values are wrong ..was just as a test.
After that, I figured out that the jpg thumbnail files looks a bit better.

So, I have the next question :
Is it possible to load the dicom file in memory and then to add those tags( with a code/dicom tool ) and after that try to make the thumbails ? After that, I guess the dicom file can be dropped from memory.

"I am not sure", but I think that if you try to manipulate those tags but they are not present in the dicom file ....you will get some error.

well, that was what i found.

I would like to load up a CR dicom file here, but I don't know how.

Best Regards,

Nicolas.

[Jörg Riesmeier]

Is it possible to load the dicom file in memory and then to add those tags( with a code/dicom tool ) and after that try to make the thumbails ?

Sure, this would be possible. But, of course, you could also specify the VOI settings (Windows Center/Width) directly using the setWindow() method from the DicomImage class.

"I am not sure", but I think that if you try to manipulate those tags but they are not present in the dicom file ....you will get some error.

What do you mean by "you will get some error"?

[nicolasdicom]

Hi Jörg,

I thought it is neccessary first to add these tags to the dicom file before try to use the setWindow() method.

I was Wrong.

Regards

Nicolas

[Jörg Riesmeier]

There are different setWindow() methods. The one I was referring to is "int setWindow (const double center, const double width)".