DICOM PS3.3 2017a - Information Object Definitions

C.34.8 Patient Positioning Module
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### C.34.8 Patient Positioning Module

Table C.34.8-1 contains details about the positioning of the patient before and during the imaging procedure.

Table C.34.8-1. Patient Positioning Module Attributes

Attribute Name | Tag | Type | Attribute Description
--- | --- | --- | ---
Protocol Defined Patient Position | (0018,9947) | 1 | Patient position relative to the equipment described by the procedure protocol. See Section C.7.3.1.1.2 for Defined Terms and further explanation.
Patient Positioning Instruction Sequence | (0018,991B) | 3 | Instructions for positioning and aligning the patient for the procedure. E.g., aligning an anatomical landmark with laser crosshairs. One or more Items are permitted in this Sequence. The precise correlation between positioning and scan elements is to be described in the Instruction Text if necessary.
>Instruction Index | (0018,9915) | 1 | Identifies the order in which instruction sequence items are presented/performed. The value shall be an integer, increasing monotonically by 1, starting from 1.
>Instruction Text | (0018,9916) | 1 | A displayable string explaining what should be done.
>Instruction Description | (0018,9917) | 3 | A detailed description explaining what should be done.
>Instruction Performed Flag | (0018,9918) | 1C | Whether or not this instruction was performed. Required if the value of SOP Class UID (0008,0016) equals 1.2.840.10008.5.1.4.1.1.200.2 (CT Performed Procedure Protocol Storage). Enumerated Values: YES NO
>Instruction Performed Datetime | (0018,9919) | 1C | Date and time the instruction was performed. Required if Instruction Performed Flag (0018,9918) is present with a value of YES.
Positioning Method Code Sequence | (0018,991C) | 3 | Identifies the method for positioning the patient. Only a single Item shall be included in this Sequence. See Section C.34.8.1.
>Include Table 8.8-1 “Code Sequence Macro Attributes” | Baseline CID 1015 “Patient Alignment Methods”.
Positioning Landmark Sequence | (0018,991D) | 3 | A coded location identifying the intended landmark used as the basis for positioning. Only a single Item is permitted in this Sequence. See Section C.34.8.1.
>Include Table 10.27-1 “Reference Location Macro Attributes” | Baseline CID 1000 “CT Transverse Plane Reference Basis” for Reference Basis Code Sequence (0018,9902) Baseline CID 1010 “Reference Geometry - Planes” for Reference Geometry Code Sequence (0018,9903)
Target Frame of Reference UID | (0018,991E) | 3 | UID of the Frame of Reference of another dataset to which the current procedure is intended to be roughly aligned. ### Note For example, in a performed protocol it may be useful to record the Frame of Reference UID used in a prior study that was used as a reference. The Frame of Reference UID (0020,0052) in the image instances resulting from the performance of this protocol will likely be different than this Target Frame of Reference UID since perfect alignment is likely unachievable.
Target Position Reference Indicator | (0020,103F) | 3 | Position Reference Indicator for the Target Frame of Reference UID (0018,991E). See Section C.34.8.1.
Anatomic Region Sequence | (0008,2218) | 2 | Identifies the general anatomic region imaged by the Protocol. See Section C.34.8.2. Zero or one Item shall be included in this Sequence.
>Include Table 8.8-1 “Code Sequence Macro Attributes” | Baseline CID 4031 “Common Anatomic Regions”.
>Anatomic Region Modifier Sequence | (0008,2220) | 3 | Sequence of Items that modifies the anatomic region of interest of this Instance. See Section C.34.8.2. One or more Items are permitted in this Sequence.
>>Include Table 8.8-1 “Code Sequence Macro Attributes” | Defined CID is CID 2.
Primary Anatomic Structure Sequence | (0008,2228) | 2 | Identifies the primary anatomic structure(s) of interest in this Protocol. Zero or more Items shall be included in this Sequence.
>Include Table 8.8-1 “Code Sequence Macro Attributes” |
>Primary Anatomic Structure Modifier Sequence | (0008,2230) | 3 | Sequence of Items that modifies the primary anatomic structure of interest in this Instance. One or more Items are permitted in this Sequence.
>>Include Table 8.8-1 “Code Sequence Macro Attributes” | Defined CID is CID 2.

#### C.34.8.1 Positioning Targets

The specific method by which the referenced localizer images, photos of patient skin marks, landmarks, or frames of reference are used to position the patient, is communicated by referencing the associated code in the Positioning Method Code Sequence (0018,991C).

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DICOM PS3.3 2017a - Information Object Definitions