.. _anonymisation:

Anonymisation
===============

*Anonymisation of DICOM data in hurahura*

Anonymisation of DICOM data in hurahura is achieved via the use of the *spydcmtk* library.

See: https://pypi.org/project/spydcmtk/ for more information on the spydcmtk library.

Anonymisation can be controlled by the configuration file or by the command line.

In the configuration file *anon_level* may be set to:

- **NONE**: No anonymisation is performed.
- **SOFT**: *Appropriate for in-house use*

    - The patient name is anonymised in DICOM files by replacing with an empty string.
    - The PatientID is retained in META file and DICOM files.
    - All PN tags are replaced with an empty string or ``"anonymous"`` as appropriate.
    - Date of birth, institution and adresses are anonymised.
    - In the Meta file the ``"NAME"`` (surname) and ``"FIRST_NAMES"`` tags are encoded with the subject ID.
    - This is recoverable if necessary. 
    
        - Functions:  ``AbstractSubject.getName()``, and ``AbstractSubject.getName_FirstNames()`` will return decoded names.
    - The age is retained in the META file.
    
- **HARD**: *Appropriate for public release / sharing*

    - The patient name is anonymised in DICOM files by replacing with an empty string.
    - The PatientID is anonymised in DICOM files by replacing with an empty string.
    - All PN tags are replaced with an empty string or ``"anonymous"`` as appropriate.
    - Date of birth, institution and adresses are anonymised.
    - In the Meta file the ``"NAME"`` (surname) and ``"FIRST_NAMES"`` tags are set to encoded versions of ``"Name-Unknown"`` and ``"FirstNames-Unknown"``.
    
        - Functions: ``AbstractSubject.getName()`` and ``AbstractSubject.getName_FirstNames()`` will return ``"Name-Unknown"`` and ``"FirstNames-Unknown"`` respectively.
    - The age is retained in the META file.

Alternatively, the anonymisation level can be specified for each subject via the command line:

.. code-block:: bash

    hurahura -s N -anon SubjABC

    # Anonymise subject N with name "SubjABC" using the SOFT anonymisation level.

Even deeper control is possible at a code level by accessing the ``AbstractSubject`` class and using the ``anonymise`` method.