Understanding DICOM Application Level Confidentiality Profile and Options

Question

I am trying to make sense of the table:

• Table E.1-1. Application Level Confidentiality Profile Attributes

Let's consider the first attribute:

Accession Number (0008,0050)

I see that this DICOM attribute is never listed in any option (eg. 'Clean Desc. Opt.'). This means that an application which claims conformance to an Application Level Confidentiality Profile and Options as a de-identifier is required to apply the 'Z' action code (as if there was an implicit 'C' default action code in an invisible column):

replace with a zero length value, or a non-zero length value that may be a dummy value and consistent with the VR

Now if we move to the second attribute in the table:

Acquisition Comments (0018,4000)

We see that this attribute is listed in one and only one option 'Clean Desc. Opt.' with action code 'C' (there is no option listed with an explicit 'K' action code). The question why is that ? If we assume there is always an implicit default 'C' action code why is the standard listing it explicitly in a particular column ?

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From my understanding when 'Clean Desc. Opt.' is used, the following behavior occur:

1. De-identification Action Code 'Z' is used for Accession Number (0008,0050)
2. De-identification Action Code 'X' is used for Acquisition Comments (0018,4000) (explicit 'C' action)

when 'Clean Desc. Opt.' is not used, the following behavior occur:

1. De-identification Action Code 'Z' is used for Accession Number (0008,0050)
2. De-identification Action Code 'X' is used for Acquisition Comments (0018,4000) (no explicit 'C' action)

Answer 1

Thanks to the helpful comments from @J.Riesmeier:

An application claiming conformance to the Basic Application Level Confidentiality Profile (without any options), shall remove the Acquisition Comments (0018,4000) attribute. If the Clean Descriptors Option is supported, the value of this attribute should be "cleaned" instead, i.e. "replace[d] with values of similar meaning known not to contain identifying information and consistent with the VR". Details on this particular option are described in PS3.15 section E.3.5.

I can answer my own question. So basically the scenario should be read as follow:

When 'Clean Desc. Opt.' is not used, the following behavior occur:

1. De-identification Action Code 'Z' is used for Accession Number (0008,0050)
2. De-identification Action Code 'X' is used for Acquisition Comments (0018,4000)

When 'Clean Desc. Opt.' is used, the following behavior occur:

1. De-identification Action Code 'Z' is used for Accession Number (0008,0050)
2. De-identification Action Code 'C' is used for Acquisition Comments (0018,4000)

Reference:

• Table E.1-1a. De-identification Action Codes