# dicomdir.py
"""Module for DicomDir class"""
#
# Copyright (c) 2013 Darcy Mason
# This file is part of pydicom, released under a modified MIT license.
# See the file LICENSE included with this distribution, also
# available at https://github.com/pydicom/pydicom
#
from pydicom.errors import InvalidDicomError
from pydicom.dataset import FileDataset
[docs]class DicomDir(FileDataset):
"""Hold a DICOMDIR dataset read from file.
Derived from FileDataset, but additional
methods are available,
specific to the Directory structure
"""
def __init__(self,
filename_or_obj,
dataset,
preamble=None,
file_meta=None,
is_implicit_VR=True,
is_little_endian=True):
"""Initialize a DICOMDIR dataset read from a DICOM file
Carries forward all the initialization from
FileDataset class
:param filename: full path and filename to the file.
Use None if is a BytesIO.
:param dataset: some form of dictionary, usually
a Dataset from read_dataset()
:param preamble: the 128-byte DICOM preamble
:param file_meta: the file meta info dataset,
as returned by _read_file_meta,
or an empty dataset if no file meta
information is in the file
:param is_implicit_VR: True if implicit VR transfer syntax used;
False if explicit VR. Default is True.
:param is_little_endian: True if little-endian transfer syntax used;
False if big-endian. Default is True.
"""
# Usually this class is created through filereader.read_partial,
# and it checks class SOP, but in case of direct creation,
# check here also
if file_meta:
class_uid = file_meta.MediaStorageSOPClassUID
if not class_uid.name == "Media Storage Directory Storage":
msg = "SOP Class is not Media Storage Directory (DICOMDIR)"
raise InvalidDicomError(msg)
FileDataset.__init__(
self,
filename_or_obj,
dataset,
preamble,
file_meta,
is_implicit_VR=True,
is_little_endian=True)
self.parse_records()
[docs] def parse_records(self):
"""Build the hierarchy of given directory records, and structure
into Patient, Studies, Series, Images hierarchy.
This is intended for initial read of file only,
it will not reorganize correctly if records are changed.
:return: None
"""
# Define a helper function for organizing the records
def get_siblings(record, map_offset_to_record):
"""Return a list of all siblings of the given directory record,
including itself.
"""
sibling_list = [record]
current_record = record
while current_record.OffsetOfTheNextDirectoryRecord:
offset_of_next = current_record.OffsetOfTheNextDirectoryRecord
sibling = map_offset_to_record[offset_of_next]
sibling_list.append(sibling)
current_record = sibling
return sibling_list
# Build the mapping from file offsets to records
records = self.DirectoryRecordSequence
map_offset_to_record = {}
for record in records:
offset = record.seq_item_tell
map_offset_to_record[offset] = record
# logging.debug("Record offsets: " + map_offset_to_record.keys())
# Find the children of each record
for record in records:
child_offset = record.OffsetOfReferencedLowerLevelDirectoryEntity
if child_offset:
child = map_offset_to_record[child_offset]
record.children = get_siblings(child, map_offset_to_record)
else:
record.children = []
# Find the top-level records : siblings of the first record
self.patient_records = get_siblings(records[0], map_offset_to_record)