Digital Imaging and Communications in Medicine (DICOM)

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We all are brothers and sisters
Chapter 5 Parlez-Vous DICOM?
As already mentioned, all patients with the same Patient ID are expected
to be the same person in DICOM. I recently ran into the most interesting
case of patient ID misuse in one well-respected hospital. All patients
arriving without ID entries were labeled with “W/I” patient ID, standing
for “without ID”. This was done daily for a large number of exams, essentially
merging all these patients into one as far as DICOM was concerned.
Consequently, PACS software was not able to distinguish between these
patients.
If no ID is available, even using patient initials with birth date (for example,
JS19670102) would work much better than “W/I”.
You can find in the DICOM Data Dictionary another attribute called “Other
Patient IDs” (0010,1001). It was provided to mitigate the problem of multiple
IDs for the same patient, but it is rarely used in DICOM software. The reason is
obvious: it is much better to enforce a consistent single-ID policy than to deal
with a list of different IDs for the same patient (possibly overlapping with other
patients).
Is there any way to deal with Patient ID inconsistencies? Practically, yes.
Good DICOM software never relies on the Patient ID attribute alone, and always
implements some additional logic to verify patient identity. This logic is
based on other data available in DICOM data elements. Patient name, date of
birth, sex, last study date, weight, size, and a few other tags can be used to make
intelligent conclusions about patient similarity and identity. For example, if all
of these parameters coincided for two patients with different patient IDs, there
is strong reason to believe that the patients are indeed the same person and that
the IDs need to be reset to the same ID (the one used first). The same approach
is used to merge patients with misspelled names and other data errors. Different
patient merge functions are often implemented in PACS software.
The same method is also used to split patients if they were erroneously
merged (for example, if the same Patient ID was mistakenly assigned to two different
people). I remember an imaging center where all Patient IDs were threedigit
numbers; but all you can do with the 000–999 numbers is to ID a thousand
patients. When you run out of these thousand options, you will have to start
recycling the same IDs for the other patients, thereby erroneously merging different
people. Using short, easy IDs can hardly make your work easier.
Patient splitting and merging should not be done automatically. When a
DICOM program detects that splitting or merging needs to be done, it should
somehow flag the suspected records and notify its human administrator. No
matter how complex the program logic might be, it could result in false merges
and splits, and human assistance to avoid these problems is important.
As the role of decentralized PACS increases and regional or national systems
come to replace the local ones, the demand for correct and consistent