def get_anonymous_replacement_value(keyword,
current_value=None,
replacement_strategy=None):
"""Get an appropriate anonymisation value for a DICOM element
based on its value representation (VR)
Parameters
----------
keyword: text string that is the pydicom name for the DICOM attribute/element
current_value: optional, the value that is currently assigned to the element
replacement_strategy: optional, a dispatch dictionary whose keys are the text representation
of the VR of the element, and whose values are function references that take the current value
of the element.
Returns
-------
A value that is a suitable replacement for the element whose attributes are identified by the keyword
TODO
----
Address VR of CS to ensure DICOM conformance and if possible, interoperability
CS typically implies a defined set of values, or in some cases, a strict enumeration of values
and replacement with a value that is not in a defined set will often break interoperability.
Replacement with a value that is not in an enumerated set breaks DICOM conformance.
"""
vr = get_baseline_keyword_vr_dict()[keyword]
if vr == "CS":
# An example, although this exact code breaks unit tests because
# the unit tests are expecting the CS hardcoded replacement string "ANON"
# if keyword == "PatientSex":
# replacement_value = "O" # or one can replace with an empty string because PatientSex is typically type 2
# else:
logging.warning(
"Keyword %s has Value Representation CS and may require special processing to avoid breaking DICOM conformance or interoperability",
keyword,
)
# elif ...
if replacement_strategy is None:
replacement_strategy = strategy.ANONYMISATION_HARDCODE_DISPATCH
try:
replacement_value = replacement_strategy[vr](current_value)
except KeyError:
logging.error(
"Unable to anonymise %s with VR %s, current value is %s",
keyword,
vr,
current_value,
)
raise
return replacement_value
def _anonymise_tags(ds_anon, keywords_to_anonymise, replace_values):
"""Anonymise all desired DICOM elements.
"""
for keyword in keywords_to_anonymise:
if hasattr(ds_anon, keyword):
if replace_values:
replacement_value = get_anonymous_replacement_value(keyword)
else:
if get_baseline_keyword_vr_dict()[keyword] in ("OB", "OW"):
replacement_value = (0).to_bytes(2, "little")
else:
replacement_value = ""
setattr(ds_anon, keyword, replacement_value)
return ds_anon
def anonymise_tags(ds_anon,
keywords_to_anonymise,
replace_values,
replacement_strategy=None):
"""Anonymise all desired DICOM elements.
"""
if not replace_values and replacement_strategy is not None:
logging.warning(
"Conflicting approach to anonymisation specified, a replacement strategy was specified in addition to a directive"
"to eliminate values rather than replace them. Adhering to directive to eliminate values"
)
for keyword in keywords_to_anonymise:
if hasattr(ds_anon, keyword):
if replace_values:
if ds_anon[keyword].value in ("", None, []):
logging.debug(
"%s has value of empty list, None or empty string, no need to modify to anonymise",
keyword,
)
continue
replacement_value = get_anonymous_replacement_value(
keyword,
current_value=ds_anon[keyword].value,
replacement_strategy=replacement_strategy,
)
else:
if get_baseline_keyword_vr_dict()[keyword] in ("OB", "OW"):
replacement_value = (0).to_bytes(2, "little")
else:
replacement_value = ""
setattr(ds_anon, keyword, replacement_value)
remaining_seq_only_list = [
x for x in ds_anon
if (x.VR == "SQ" and x.name not in keywords_to_anonymise)
]
for seq in remaining_seq_only_list:
for seq_item in seq.value:
anonymise_tags(
seq_item,
keywords_to_anonymise,
replace_values,
replacement_strategy=replacement_strategy,
)
return ds_anon
def _anonymise_tags(ds_anon, keywords_to_anonymise, replace_values):
"""Anonymise all desired DICOM elements.
"""
for keyword in keywords_to_anonymise:
if hasattr(ds_anon, keyword):
if replace_values:
replacement_value = get_anonymous_replacement_value(keyword)
else:
if get_baseline_keyword_vr_dict()[keyword] in ("OB", "OW"):
replacement_value = (0).to_bytes(2, "little")
else:
replacement_value = ""
setattr(ds_anon, keyword, replacement_value)
remaining_seq_only_list = [
x for x in ds_anon if (x.VR == "SQ" and x.name not in keywords_to_anonymise)
]
for seq in remaining_seq_only_list:
for seq_item in seq.value:
_anonymise_tags(seq_item, keywords_to_anonymise, replace_values)
return ds_anon
def get_anonymous_replacement_value(keyword):
"""Get an appropriate dummy anonymisation value for a DICOM element
based on its value representation (VR)
"""
vr = get_baseline_keyword_vr_dict()[keyword]
return get_vr_anonymous_replacement_value_dict()[vr]