Referenced Waveform Channels

[andycaesar]

Hi,
it is not clear to me which should be the "format" and the meaning of the ds.ReferencedWaveformChannels value. Inspecting a few DCM files I've found:

[1,0]

it should be type

US (Unsigned Short): int

It would be correct using one of the following forms?

ds.ReferencedWaveformChannels = [1,0]

or

ds.ReferencedWaveformChannels = 0

Somebody could also explain to me the meaning of these two forms?

Cheers
AC

[mrbean-bremen]

From the DICOM standard:

List of channels in Waveform to which the reference applies.

Required if the Referenced SOP Instance is a Waveform that contains multiple Channels and the reference does not apply to all Channels of all Multiplex Groups.

Referenced Waveform Channels (0040,A0B0) is a multi-value Attribute that lists the channels referenced. Each channel is specified as a pair of values (M,C), where the first value is the Item number of Waveform Sequence (5400,0100) in the referenced object (i.e., the Multiplex Group Number), and the second value is the Item number of Channel Definition Sequence (003A,0200) (i.e., the Channel Number) within the multiplex group.

If the specified channel number is 0, the annotation applies to all channels in the specified multiplex group.

That means, that you always need at least 2 numbers (the value multiplicity is 2..2n), and the first representation [1, 0] is correct (meaning that all channels in group 1 are referenced).
The second form is not valid DICOM - I would guess that it is used to indicate that all channels of all groups are referenced, though the correct way to handle this would be to omit the attribute. Note that adding an empty attribute is also not allowed (1C means the value must exist and not be empty under a certain condition, and not exist otherwise).