Digital Imaging and Communications in Medicine (DICOM)

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Chapter 5 Parlez-Vous DICOM?
signed long, unsigned long, floating point single, and floating point double,
respectively) are used to represent single numbers (sometimes a few numbers
concatenated together). OB, OW, and OF (other byte string, other word string,
and other float string, respectively) are used for long numerical strings. Think
about storing a pixel sequence from a digital image, for example. In this case,
each number in the sequence will have the same byte size (1, 2, or 4 bytes, respectively),
and they all will be concatenated into a long binary sequence. Only
one type, OB, uses numbers 1 byte long. The others have more than 1 byte, so
they will be affected by Big/Little Endian byte ordering.
Finally, AT (attribute tag) stores a pair of 2-byte numbers. This data type
corresponds to (group, element) tagging of all DICOM attributes, as we will
soon see in 5.4. Thus, AT type, unlike the other number types, is used strictly
for enumerating DICOM data attributes.
5.3.7
PN: Storing Person’s Names
The PN (Person’s Name) VR encodes the entire person’s name. Unfortunately,
DICOM uses a single field to hold this value. That is, the entire person name
(first, last, middle, and so on) will be recorded in a single PN-type VR. Easy to
predict, this often leads to confusion in medical workflow and software when
“John Smith” can be written as “John Smith”, “Smith^John”, or even “Smith,
John”. To eliminate this uncertainty, DICOM prescribes the following name
order:
FamilyName^GivenName^MiddleName^NamePrefix^NameSuffix
all separated by the caret (^) character. Compare this to our examples in the
VR table. However, in a multifaceted medical environment, this order is often
permuted, resulting in permanently lost information or misidentified patients.
There are two remedies to this problem:
1. To identify patients, always use patient IDs and not the patients’ names. Using
the patient ID leaves little room for spelling errors.
2. When searching for (patient) names on your PACS or any DICOM software
in general, use wildcards such as the asterisk (*) meaning “any text”. As we
already know, wildcard searches are standard in DICOM. Typing “*Smith*”
in your patient name search box will definitely return all patients with
“Smith” appearing somewhere in their names, so your patient information
won’t be missed or affected by name order. In fact, some DICOM programs
automatically add wildcards to your name searches, to return all similarlooking
names.
Moreover, certain DICOM applications are smart enough to go beyond wildcard
matching when they implement phonetic matching to find the names that