DICOM Letter Ballot: Supplement 231

DICOM Letter Ballot Supplement 231

Hello All,

Please review the following letter ballot and advise by March 8th, 2023 if you have any comments or concerns.

DICOM Letter Ballot: Supplement 231
Variable Modality LUT Softcopy Presentation State

Issued: 2023-02-03
Ballot closes: 2023-03-10

The following is a Letter Ballot seeking DICOM Standard Committee (DSC) approval of the Proposed Supplement 231: Variable Modality LUT Softcopy Presentation State. Only the officially designated voting representatives (or alternates) of the Members of the DICOM Standards Committee are invited and entitled to cast a ballot. Others on the Committee receive a copy of this ballot as a courtesy so that all will be apprised of anticipated revisions or extensions to the DICOM Standard.

Scope and Field of Application
This supplement defines a new Presentation State SOP Class for both grayscale and pseudo-color. This new SOP class differs from existing SOP classes in that it allows the Modality LUT to be controlled for each image or frame. This is intended for modalities in which the dynamic range varies between images or frames, resulting in each referenced image having a different Modality LUT.

In DICOM, Presentation States are intended to be a complete specification of the presentation in order to provide consistent presentation. An aspect of this is that PS3.4 N.2.1.1 requires the Modality LUT in the image be ignored in the presence of a GSPS object, even if no Modality LUT is explicitly defined in the GSPS. Further, the GSPS only supports one Modality LUT. This is problematic in cases such as PET or MR, in which the dynamic range of the measured values varies between images. Without this new SOP Class, the GSPS creator would be forced to render multiple GSPS objects, one for Modality LUT change.

Supplement 231 can be accessed on the FTP:

Word Document format:
ftp://medical.nema.org/medical/dicom/Supps/LB/sup231_lb_VariableModalityLUT_PS.docx

PDF format:
ftp://medical.nema.org/medical/dicom/Supps/LB/sup231_lb_VariableModalityLUT_PS.pdf

PowerPoint Overview:
ftp://medical.nema.org/medical/dicom/Supps/LB/sup231_lb_VariableModalityLUT_PS.pptx