DICOM PS3.3 2017b - Information Object Definitions

C.34.11 Defined CT Reconstruction Module
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### C.34.11 Defined CT Reconstruction Module

Table C.34.11-1 contains specification of acceptable values and ranges of reconstruction parameters for an imaging procedure.

Table C.34.11-1. Defined CT Reconstruction Module Attributes

Attribute Name | Tag | Type | Attribute Description
--- | --- | --- | ---
Reconstruction Protocol Element Specification Sequence | (0018,9933) | 1 | Specification of the parameters for reconstruction of the acquired data of an imaging procedure. There shall be one item in this sequence for each reconstruction protocol element in the Protocol. See Section C.34.11.1. One or more Items shall be included in this Sequence.
>Protocol Element Number | (0018,9921) | 1 | The Protocol Element Number of the Reconstruction Protocol Element being specified in this item.
>Parameters Specification Sequence | (0018,9913) | 3 | Constraints on reconstruction parameters. One or more Items are permitted in this Sequence.
>>Include Table 10.25-1 “Attribute Value Constraint Macro Attributes” | Only Attributes defined in Table C.34.12-1 (i.e., in the Reconstruction Protocol Element Sequence (0018,9934) in the Performed CT Reconstruction Module) and private Data Elements associated with this reconstruction protocol element may be specified as Selector Attributes. The semantics of values of Constraint Violation Significance (0082,0036) in the macro are assigned in C.34.9.3. The same Attribute shall not appear in more than one item in the sequence with the same values for Selector Sequence Pointer (0072,0052) and Selector Sequence Pointer Items (0074,1057).
>>Modifiable Constraint Flag | (0082,0038) | 1C | Whether this constraint may be encoded in a derived instance with a different value. See Section C.34.9.4. Required if the constraint may not be modified, may be present otherwise. Enumerated Values: YES The constraint may be modified. NO The constraint may not be modified.

Attributes that might commonly be specified here include:

- Reconstruction Algorithm (0018,9315)

- Convolution Kernel (0018,1210)

- Reconstruction Diameter (0018,1100)

- Slice Thickness (0018,0050)

- Pixel Spacing (0028,0030)

#### C.34.11.1 Reconstruction Protocol Elements

A CT Protocol frequently specifies multiple reconstructions. For example, a single helical Acquisition Protocol Element may be reconstructed once as thin slices and a second time as thick slices.

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DICOM PS3.3 2017b - Information Object Definitions