| Tag | (0018,9920) |
|---|---|
| Type | Required, Empty if Unknown (2) |
| Keyword | AcquisitionProtocolElementSequence |
| Value Multiplicity | 1 |
| Value Representation | Sequence (SQ) |
Parameter values for each Protocol Element in the acquisition protocol. Each Item in the Sequence describes one Element. Elements are performed in the order of their Protocol Element Number (0018,9921).
See Section C.34.9.1.
Zero or more Items shall be included in this Sequence.
A CT Protocol usually includes more than one Acquisition Protocol Element. For example, a chest Protocol might include three elements in total: two localizer CT radiographs (AP and Lateral), and a single helical scan.
Since all parameters will be nested inside an Acquisition Protocol Element Sequence (0018,9920) and some of the parameters will be further nested inside a CT X-Ray Details Sequence (0018,9325), close attention must be paid to the use of the Selector Sequence Pointer (0072,0052) in the Attribute Value Constraint Macro. Illustrative examples are provided in Table C.34.9-2.
Table C.34.9-2. Example Usage of Selector Macro Attributes for Acquisition Constraints
|
Example |
Selector Attribute (0072,0026) |
Selector Value Number (0072,0028) |
Selector Sequence Pointer (0072,0052) |
Selector Sequence Pointer Items (0074,1057) |
Example Constraint |
|---|---|---|---|---|---|
|
Constrain the value of Element Name (0018,9922) of the first Item in the Acquisition Protocol Element Sequence (0018,9920) |
(0018,9922) |
1 |
(0018,9920) |
1 |
EQUAL"Localizer (AP) " |
|
Constrain the value of Table Speed (0018,9309) of the second Item in the Acquisition Protocol Element Sequence (0018,9920) |
(0018,9309) |
1 |
(0018,9920) |
2 |
EQUAL14 mm/sec |
|
Constrain the value of KVP (0018,0060) of the first beam in the CT X-Ray Details Sequence (0018,9325) of the second Item in the Acquisition Protocol Element Sequence (0018,9920) |
(0018,0060) |
1 |
(0018,9920), (0018,9325) |
2\1 |
RANGE_INCL(120,140) |
|
Constrain the first and second value of Exposure Modulation Type (0018,9323) of the second beam in the CT X-Ray Details Sequence (0018,9325) of the third Item in the Acquisition Protocol Element Sequence (0018,9920) |
(0018,9323) |
1 |
(0018,9920), (0018,9325) |
3\2 |
EQUAL"ANGULAR" |
|
(0018,9323) |
2 |
(0018,9920), (0018,9325) |
3\2 |
EQUAL"ORGAN_BASED" |