6.2.3.5. Image Laterality (0020,0062)

In DICOM, laterality is used to define body parts which come in pairs, for example knees, ears, eyes, etc. It is not used to describe the side of the body being imaged. For example, an image of the left side of the right eye would have laterality right, even though the image is portraying the left side of the eye. In other words, this is the laterality of (possibly paired) body part (as described in Anatomic Region Sequence (0008,2218)) examined.

Patient Orientation (0020,0020) should be enough to define the side of the anatomy being viewed.

6.2.3.5.1. Allowed Values

From DICOM CID-244

DICOM Enumerated Value	SNOMED Code
L	(7771000, SCT, “Left”)
R	(24028007, SCT, “Right”)
U	(66459002, SCT, “Unilateral”)
B	(51440002, SCT, “Bilateral”)

Note

When creating the DICOM object, DICOM requires an enumerated value (aka string) for this tag. You should therefore always use the string in the DICOM Enumerated Value column of the table above.

You are encouraged to use the SNOMED code for other usages.

6.2.3.5.2. Choosing the Correct Laterality

Consider the following logic when choosing laterality.

U	Unpaired	Used for most orthodontic images.
L	Left	Only use if this Series is of Mastoid bone, Maxilla or Temporomandibular joint. For all other anatomic regions containing one or both sides, set to ‘U’.
R	Right	Only use if this Series is of Mastoid bone, Maxilla or Temporomandibular joint. For all other anatomic regions containing one or both sides, set to ‘U’.
B	Both	Only use if this Series is of Mastoid bone, Maxilla or Temporomandibular joint. For all other anatomic regions containing one or both sides, set to ‘U’. This is almost never used. For example, a frontal face smiling photograph, would have Image Laterality of ‘U’. However, an image which would contain both the left Maxilla and the right Maxilla in the same frame (image) (for example making use of mirrors or by merging two images into one) would have an Image Laterality of ‘B’.

The above table was compiled using the following considerations:

1. Image Laterality (0020,0062) Shall be consistent with any laterality information contained in Primary Anatomic Structure Modifier Sequence (0008,2230). DICOM PS 3.3 Section 10.5 General Anatomy Macros discusses the relationship between Image Laterality (0020,0062) and Primary Anatomic Structure Modifier Sequence (0008,2230):

   1. “Laterality is often encoded in a separate Attribute, Image Laterality (0020,0062) or Frame Laterality (0020,9072), rather than in Anatomic Region Modifier Sequence (0008,2220) or Primary Anatomic Structure Modifier Sequence (0008,2230).” This means that even thought the Laterality should be encoded in the Anatomic Region Modifier Sequence, it is often encoded in Image Laterality. Since these two shall be consistent, DICOM provides a mapping between the two (see below, one is an enumerated value as CS the other a code sequence).

   2. The section references Part 16 Table L-5, a table which defines whether a specific anatomic region is to be considered a paired structure or not. Below, we report a table of those body parts relevant to orthodontic visible light images.

2. Laterality (0020,0060) (a Series level Attribute) must be absent, because

   1. this series could contain images of different Laterality and

   2. because Laterality (0020,0060) only allows ‘L’ and ‘R’ enumerated values, which are not sufficient to describe these images.

(excerpt from DICOM Part 16 Table L-5 with orthodontic domain relevant regions)

SNOMED Code Value	Code Meaning	Paired Structure
60819002	Buccal region of face	N
89545001	Face	N
69536005	Head	N
774007	Head and Neck	N
661005	Jaw region	N
91609006	Mandible	N
59066005	Mastoid bone	Y
70925003	Maxilla	Y
123851003	Mouth	N
89546000	Skull	N
42575006	Sella turcica	N
170887008	Submental	N
53620006	Temporomandibular joint	Y
21974007	Tongue	N