E.3.10 Retain Safe Private Option
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### E.3.10 Retain Safe Private Option

By definition, Private Attributes contain proprietary information, in many cases the nature of which is known only to the vendor and not publicly documented.

However, some Private Attributes may be necessary for the desired application. For example, specific technique information such as CT helical span pitch, or pixel value transformation, such as PET SUV rescale factors, may only be available in Private Attributes since the information is either not defined in Standard Attributes, or was added to the DICOM Standard after the acquisition device was manufactured.

When this Option is specified in addition to an Application Level Confidentiality Profile, Private Attributes that are known by the de-identifier to be safe from identity leakage shall be retained, together with the Private Creator IDs that are required to fully define the retained Private Attributes; all other Private Attributes shall be removed.

When this Option is not specified, all Private Attributes shall be removed, as described in Table E.1-1.

### Note

1. A sample list of Private Attributes thought to be safe is provided here. Vendors do not guarantee them to be safe, and do not commit to sending them in any particular software version (including future products).

   Table E.3.10-1. Safe Private Attributes

   Data Element | Private Creator | VR | VM | Meaning
   --- | --- | --- | --- | ---
   (7053,xx00) | Philips PET Private Group | DS | 1 | SUV Factor - Multiplying stored pixel values by Rescale Slope then this factor results in SUVbw in g/l
   (7053,xx09) | Philips PET Private Group | DS | 1 | Activity Concentration Factor - Multiplying stored pixel values by Rescale Slope then this factor results in MBq/ml.
   (00E1,xx21) | ELSCINT1 | DS | 1 | DLP
   (01E1,xx26) | ELSCINT1 | CS | 1 | Phantom Type
   (01E1,xx50) | ELSCINT1 | DS | 1 | Acquisition Duration
   (01F1,xx01) | ELSCINT1 | CS | 1 | Acquisition Type
   (01F1,xx07) | ELSCINT1 | DS | 1 | Table Velocity
   (01F1,xx26) | ELSCINT1 | DS | 1 | Pitch
   (01F1,xx27) | ELSCINT1 | DS | 1 | Rotation Time
   (0019,xx23) | GEMS_ACQU_01 | DS | 1 | Table Speed [mm/rotation]
   (0019,xx24) | GEMS_ACQU_01 | DS | 1 | Mid Scan Time [sec]
   (0019,xx27) | GEMS_ACQU_01 | DS | 1 | Rotation Speed (Gantry Period)
   (0019,xx9E) | GEMS_ACQU_01 | LO | 1 | Internal Pulse Sequence Name
   (0043,xx27) | GEMS_PARM_01 | SH | 1 | Scan Pitch Ratio in the form "n.nnn:1"
   (0045,xx01) | GEMS_HELIOS_01 | SS | 1 | Number of Macro Rows in Detector
   (0045,xx02) | GEMS_HELIOS_01 | FL | 1 | Macro width at ISO Center
   (0903,xx10) | GEIIS PACS | US | 1 | Reject Image Flag
   (0903,xx11) | GEIIS PACS | US | 1 | Significant Flag
   (0903,xx12) | GEIIS PACS | US | 1 | Confidential Flag
   (2001,xx03) | Philips Imaging DD 001 | FL | 1 | Diffusion B-Factor
   (2001,xx04) | Philips Imaging DD 001 | CS | 1 | Diffusion Direction
   (0019,xx0C) | SIEMENS MR HEADER | IS | 1 | B Value
   (0019,xx0D) | SIEMENS MR HEADER | CS | 1 | Diffusion Directionality
   (0019,xx0E) | SIEMENS MR HEADER | FD | 3 | Diffusion Gradient Direction
   (0019,xx27) | SIEMENS MR HEADER | FD | 6 | B Matrix
   (0043,xx39) | GEMS_PARM_01 | IS | 4 | 1stvalue is B Value
   (0043,xx6F) | GEMS_PARM_01 | DS | 3-4 | Scanner Table Entry + Gradient Coil Selected
   (0025,xx07) | GEMS_SERS_01 | SL | 1 | Images in Series
   (7E01,xx01) | HOLOGIC, Inc. | LO | 1 | Codec Version
   (7E01,xx02) | HOLOGIC, Inc. | SH | 1 | Codec Content Type
   (7E01,xx10) | HOLOGIC, Inc. | SQ | 1 | High Resolution Data Sequence
   (7E01,xx11) | HOLOGIC, Inc. | SQ | 1 | Low Resolution Data Sequence
   (7E01,xx12) | HOLOGIC, Inc. | OB | 1 | Codec Content
   (0099,xx01) | NQHeader | UI | 1 | Version
   (0099,xx02) | NQHeader | UI | 1 | Analyzed Series UID
   (0099,xx04) | NQHeader | SS | 1 | Return Code
   (0099,xx05) | NQHeader | LT | 1 | Return Message
   (0099,xx10) | NQHeader | FL | 1 | MI
   (0099,xx20) | NQHeader | SH | 1 | Units
   (0099,xx21) | NQHeader | FL | 1 | ICV
   (0199,xx01) | NQLeft | FL | 1 | Left Cortical White Matter
   (0199,xx02) | NQLeft | FL | 1 | Left Cortical Gray Matter
   (0199,xx03) | NQLeft | FL | 1 | Left 3rd Ventricle
   (0199,xx04) | NQLeft | FL | 1 | Left 4th Ventricle
   (0199,xx05) | NQLeft | FL | 1 | Left 5th Ventricle
   (0199,xx06) | NQLeft | FL | 1 | Left Lateral Ventricle
   (0199,xx07) | NQLeft | FL | 1 | Left Inferior Lateral Ventricle
   (0199,xx08) | NQLeft | FL | 1 | Left Inferior CSF
   (0199,xx09) | NQLeft | FL | 1 | Left Cerebellar White Matter
   (0199,xx0a) | NQLeft | FL | 1 | Left Cerebellar Gray Matter
   (0199,xx0b) | NQLeft | FL | 1 | Left Hippocampus
   (0199,xx0c) | NQLeft | FL | 1 | Left Amygdala
   (0199,xx0d) | NQLeft | FL | 1 | Left Thalamus
   (0199,xx0e) | NQLeft | FL | 1 | Left Caudate
   (0199,xx0f) | NQLeft | FL | 1 | Left Putamen
   (0199,xx10) | NQLeft | FL | 1 | Left Pallidum
   (0199,xx11) | NQLeft | FL | 1 | Left Ventral Diencephalon
   (0199,xx12) | NQLeft | FL | 1 | Left Nucleus Accumbens
   (0199,xx13) | NQLeft | FL | 1 | Left Brain Stem
   (0199,xx14) | NQLeft | FL | 1 | Left Exterior CSF
   (0199,xx15) | NQLeft | FL | 1 | Left WM Hypo
   (0199,xx16) | NQLeft | FL | 1 | Left Other
   (0299,xx01) | NQRight | FL | 1 | Right Cortical White Matter
   (0299,xx02) | NQRight | FL | 1 | Right Cortical Gray Matter
   (0299,xx03) | NQRight | FL | 1 | Right 3rd Ventricle
   (0299,xx04) | NQRight | FL | 1 | Right 4th Ventricle
   (0299,xx05) | NQRight | FL | 1 | Right 5th Ventricle
   (0299,xx06) | NQRight | FL | 1 | Right Lateral Ventricle
   (0299,xx07) | NQRight | FL | 1 | Right Inferior Lateral Ventricle
   (0299,xx08) | NQRight | FL | 1 | Right Inferior CSF
   (0299,xx09) | NQRight | FL | 1 | Right Cerebellar White Matter
   (0299,xx0a) | NQRight | FL | 1 | Right Cerebellar Gray Matter
   (0299,xx0b) | NQRight | FL | 1 | Right Hippocampus
   (0299,xx0c) | NQRight | FL | 1 | Right Amygdala
   (0299,xx0d) | NQRight | FL | 1 | Right Thalamus
   (0299,xx0e) | NQRight | FL | 1 | Right Caudate
   (0299,xx0f) | NQRight | FL | 1 | Right Putamen
   (0299,xx10) | NQRight | FL | 1 | Right Pallidum
   (0299,xx11) | NQRight | FL | 1 | Right Ventral Diencephalon
   (0299,xx12) | NQRight | FL | 1 | Right Nucleus Accumbens
   (0299,xx13) | NQRight | FL | 1 | Right Brain Stem
   (0299,xx14) | NQRight | FL | 1 | Right Exterior CSF
   (0299,xx15) | NQRight | FL | 1 | Right WM Hypo
   (0299,xx16) | NQRight | FL | 1 | Right Other
   (2005,xx0D) | Philips MR Imaging DD 001 | FL | 1 | Scale Intercept
   (2005,xx0E) | Philips MR Imaging DD 001 | FL | 1 | Scale Slope

2. One approach to retaining Private Attributes safely, either when the VR is encoded explicitly or known from a data dictionary (such as may be derived from published DICOM Conformance Statements or previously encountered instances, perhaps by adaptively extending the data dictionary as new explicit VR instances are received), is to retain those Attributes that are numeric only. For example, one might retain US, SS, UL, SS, FL and FD binary values, and IS and DS string values that contain only valid numeric characters. One might assume that other string Value Representations are unsafe in the absence of definite confirmation from the vendor to the contrary; code strings (CS) may be an exception. Bulk binary data in OB Value representations is particularly unsafe, and may often contain entire proprietary format headers in binary or text or XML form that includes the patient's name and other identifying information.

The safe private attributes that are retained shall be described in the Conformance Statement.

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