DICOM PS3.3 2021b - Information Object Definitions

C.36.6 RT Enhanced Prescription Module (Current)
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### C.36.6 RT Enhanced Prescription Module

The RT Enhanced Prescription Module describes the delivery objectives and labels for intended treatment for a specific target, as defined by the physician.

Table C.36.6-1. RT Enhanced Prescription Module Attributes

Attribute Name | Tag | Type | Attribute Description
--- | --- | --- | ---
RT Prescription Sequence | (3010,006B) | 1 | Prescriptions to deliver therapeutic radiation. One or more Items shall be included in this Sequence.
>RT Prescription Label | (3010,0054) | 1 | User-defined label for this prescription. See Section 10.31.1.1.
>RT Prescription Index | (3010,003C) | 1 | Index of the prescription in the Sequence. The value shall start at 1 and increase monotonically by 1.
>Referenced RT Physician Intent Index | (3010,005E) | 1C | The value of the RT Physician Intent Index (3010,0058) in the RT Physician Intent Sequence (3010,0057) corresponding to the intent for which this prescription is created. Required if Referenced Parent RT Prescription Index (3010,0042) is absent. See Section C.36.6.1.5.
>Referenced Parent RT Prescription Index | (3010,0042) | 1C | The value of the RT Prescription Index (3010,003C) corresponding to a prescription that is the parent prescription to this one. This attribute shall reference a Prescription that contains Referenced RT Physician Intent Index (3010,005E). Required if the Referenced RT Physician Intent Index (3010,005E) is absent. See Section C.36.6.1.5.
>Referenced Dosimetric Objectives Sequence | (3010,0071) | 2 | References to Dosimetric Objectives in the Dosimetric Objective Sequence (3010,006C) applicable to this prescription. See Section C.36.6.1.6. Zero or more Items shall be included in this Sequence.
>>Referenced Dosimetric Objective UID | (3010,006F) | 1 | Reference to a Dosimetric Objective UID (3010,006E) in the Dosimetric Objective Sequence (3010,006C).
>>Dosimetric Objective Weight | (3010,0074) | 1C | Weight of importance to be applied to the Dosimetric Objective. A higher value means that this objective is more important. Values are only meaningful within the Items in this Sequence. The use of weight value in the process of optimization and treatment parameter definition is implementation-dependent. Required if Absolute Dosimetric Objective Flag (3010,0073) is NO.
>RT Anatomic Prescription Sequence | (3010,0060) | 1 | Prescriptions for an anatomic region. One or more Items shall be included in this Sequence.
>>Include Table 10.31-1 “Entity Labeling Macro Attributes” |
>>Therapeutic Role Category Code Sequence | (3010,0064) | 1 | The general category of the therapeutic role of this anatomic region. Only a single Item shall be included in this Sequence.
>>>Include Table 8.8-1 “Code Sequence Macro Attributes” | DCID 9503 “Radiotherapy Therapeutic Role Categories”.
>>Therapeutic Role Type Code Sequence | (3010,0065) | 1 | The specific property type of the therapeutic role of this anatomic region. Only a single Item shall be included in this Sequence. See Section C.36.6.1.1.
>>>Include Table 8.8-1 “Code Sequence Macro Attributes” | Context Groups are specified in Section C.36.6.1.1.
>>Conceptual Volume Optimization Precedence | (3010,0066) | 2 | Value used to resolve usage of overlapping regions of Conceptual Volumes during dose optimization. An overlapping region is part of the Conceptual Volume(s) with the lowest number. An overlapping region is not part of any other Conceptual Volume with a higher number. Overlapping regions with equal precedence are part of all Conceptual Volumes with the same value. Any number takes precedence over an empty value.
>>Recommended Display CIELab Value | (0062,000D) | 3 | A default triplet value in which it is recommended that the anatomy be rendered on a color display. The units are specified in PCS-Values, and the value is encoded as CIELab. See Section C.10.7.1.1.
>>Conceptual Volume Blocking Constraint | (3010,0068) | 2 | Constraints on primary radiation passing through the current Conceptual Volume. Enumerated Values: NONE No constraint. UPSTREAM The optimization is constrained to minimize primary radiation from the source passing through the current Conceptual Volume. The Conceptual Volume is upstream of the target. DOWNSTREAM The optimization is constrained to minimize primary radiation from the source passing through the current Conceptual Volume. The Conceptual Volume is downstream of the target. TOTAL The optimization is constrained to minimize primary radiation passing through the current Conceptual Volume. Primary Radiation is defined as modulated or shaped radiation, as opposed to scattered radiation or transmission radiation.
>>Conceptual Volume Category Code Sequence | (3010,0067) | 2 | The general category of this Conceptual Volume for radiotherapy purposes. Zero or one Item shall be included in this Sequence.
>>>Include Table 8.8-1 “Code Sequence Macro Attributes” | DCID 9501 “Prescription Anatomy Categories”.
>>Conceptual Volume Type Code Sequence | (3010,0069) | 1C | The specific type of this Conceptual Volume for radiotherapy purposes. Only a single Item shall be included in this Sequence. Required if Conceptual Volume Category Code Sequence (3010,0067) sequence contains one Item. See Section C.36.6.1.2.
>>>Include Table 8.8-1 “Code Sequence Macro Attributes” | Context groups are specified in Section C.36.6.1.2.
>>Conceptual Volume Type Modifier Code Sequence | (3010,006A) | 3 | The modifier of the specific type of this Conceptual Volume for radiotherapy purposes. Only a single Item is permitted in this Sequence.
>>>Include Table 8.8-1 “Code Sequence Macro Attributes” | DCID 244 “Laterality”.
>>Conceptual Volume Sequence | (3010,0025) | 1 | Conceptual Volume for which therapeutic goals are prescribed. See Section C.36.6.1.3. Only a single Item shall be included in this Sequence. The same Conceptual Volume UID (3010,0006) shall not appear in more than one Item of the RT Anatomic Prescription Sequence (3010,0060).
>>>Include Table 10.34-1 “Conceptual Volume Segmentation Reference And Combination Macro Attributes” |
>>Conceptual Volume Description | (3010,0017) | 2 | Description of the Conceptual Volume.
>Referenced RT Treatment Phase Sequence | (3010,0049) | 1C | Referenced treatment phase(s) to which this prescription applies. Required if RT Treatment Phase Intent Presence Flag (3010,0045) of this RT Physician Intent SOP Instance equals YES. One or more Items shall be included in this Sequence.
>>Referenced RT Treatment Phase Index | (3010,0040) | 1 | Value of RT Treatment Phase Index (3010,003A) in the Intended RT Treatment Phase Sequence (3010,004B) where this prescription is related to.
>Fraction-Based Relationship Sequence | (3010,0082) | 2 | The relationship of this prescription to another prescription, expressed in fractions. Zero or one Item shall be included in this Sequence. See Section C.36.6.1.4.
>>Referenced RT Prescription Index | (3010,0041) | 1 | Value of RT Prescription Index (3010,003C) in the RT Prescription Sequence (3010,006B) specifying the prescription to which the current prescription is related.
>>Fraction-Based Relationship Interval Anchor | (3010,0083) | 1 | The anchor point of this RT Prescription Sequence Item with respect to the prescription referenced by Referenced RT Prescription Index (3010,0041). Enumerated Values: START The interval is specified with respect to the start of the referenced prescription. END The interval is specified with respect to the end of the referenced prescription.
>>Number of Interval Fractions | (3010,007C) | 1 | The interval expressed in number of fractions. The Fraction-Based Relationship Interval Anchor (3010,0083) establishes the anchor point to which the interval is tied. A value of 0 means that the current prescription is intended to start simultaneously with the anchor of the related prescription. If Fraction-Based Relationship Interval Anchor (3010,0083) equals START, the value shall be 0 or positive. This is the number of fractions after the first fraction of the delivery of the referenced prescription that the delivery of the current prescription is intended to start. If Fraction-Based Relationship Interval Anchor (3010,0083) equals END, the value shall be negative or 0. This is the number of fractions prior to the last fraction of the delivery of the referenced prescription that the delivery of the current prescription is intended to start.
>Prior Treatment Dose Description | (3010,0061) | 2 | Description of radiotherapy treatment previously delivered to the patient for the purpose of evaluation of prior dose.
>Prior Treatment Reference Sequence | (3010,0062) | 2 | References to SOP Instances representing prior treatments, e.g. for the purpose of extracting information about prior dose. Zero or more Items shall be included in this Sequence.
>>Include Table 10-11 “SOP Instance Reference Macro Attributes” |
>Planning Input Information Sequence | (3010,0076) | 2 | References to SOP Instances to be used during planning for the delivery of this prescription. When there are multiple Purposes of References, one Item will be included for each purpose. Zero or more Items shall be included in this Sequence.
>>Include Table 10.37-1 “Related Information Entities Macro Attributes” | DCID 9510 “Purpose of Reference For RT Treatment Planning Input”.
>Prescription Notes | (3010,007B) | 3 | Notes on this prescription, such as special provisions for this patient's treatment or other patient conditions.
>Number of Fractions | (3010,007D) | 3 | Number of Fractions in this prescription.
>Intended Delivery Duration | (3010,007E) | 3 | Number of days across which the fractions in this prescription will be delivered.
>Fractionation Notes | (3010,007F) | 3 | Notes describing the fractionation approach.
>Delivery Time Structure Code Sequence | (3010,0088) | 3 | The time structure, i.e. fractionation type, to be used for the delivery of treatment. Zero or one Items shall be included in this Sequence.
>>Include Table 8.8-1 “Code Sequence Macro Attributes” | BCID 9533 “Delivery Time Structure”
>Include Table C.36.2.1.1-1 “Radiation Fraction Pattern Macro Attributes” |
>Treatment Technique Notes | (3010,007A) | 3 | Notes on the treatment technique to be used.
>Radiotherapy Treatment Type | (3010,0046) | 3 | Type of radiotherapy. Enumerated Values: TELETHERAPY Treatment in which the source of the radiation is at a distance from the body. BRACHYTHERAPY Treatment in which the source of radiation is placed close to the surface of the body or within the body.
>Teletherapy Radiation Type | (3010,0047) | 3 | Type of Radiation used to deliver Teletherapy. Defined Terms: PHOTON NEUTRON ELECTRON ION May be present only if Radiotherapy Treatment Type (3010,9980) has a value of TELETHERAPY.
>Brachytherapy Source Type | (3010,0048) | 3 | Type of Source used to deliver Brachytherapy. Defined Terms: ISOTOPIC ELECTRONIC May be present only if Radiotherapy Treatment Type (3010,9980) has a value of BRACHYTHERAPY.
>RT Treatment Technique Code Sequence | (3010,0080) | 3 | Treatment technique to be used. One or more Items are permitted in this Sequence.
>>Include Table 8.8-1 “Code Sequence Macro Attributes” | DCID 9524 “Radiotherapy Procedure Techniques”.
>Patient Treatment Orientation Sequence | (3010,0032) | 2 | Orientation of the Patient for the treatment. Zero or one Item shall be included in this Sequence.
>>Patient Orientation Code Sequence | (0054,0410) | 1 | Orientation of the patient with respect to gravity. See Section C.8.4.6.1.1 for further explanation. Only a single Item shall be included in this Sequence.
>>>Include Table 8.8-1 “Code Sequence Macro Attributes” | DCID 19 “Patient Orientation”.
>>>Patient Orientation Modifier Code Sequence | (0054,0412) | 1C | Sequence describing the orientation of the patient with respect to gravity. Required if needed to fully specify the orientation of the patient with respect to gravity. Only a single Item shall be included in this Sequence.
>>>>Include Table 8.8-1 “Code Sequence Macro Attributes” | DCID 20 “Patient Orientation Modifier”.
>>Patient Equipment Relationship Code Sequence | (3010,0030) | 1 | Orientation of the patient with respect to equipment. Only a single Item shall be included in this Sequence. See Section C.36.6.1.8.
>>>Include Table 8.8-1 “Code Sequence Macro Attributes” | DCID 21 “Patient Equipment Relationship”.
>Prescription Notes Sequence | (3010,0081) | 3 | Annotations on aspects of the prescription, like preparation and execution of the treatment. One or more Items are permitted in this Sequence.
>>Include Table 10-2 “Content Item Macro Attributes Description” | DTID 15300 “RT Prescription Annotation”
Dosimetric Objective Sequence | (3010,006C) | 1C | Dosimetric Objectives defined for one or more prescription within module. Each Dosimetric Objective referenced in the Referenced Dosimetric Objectives Sequence (3010,0071) shall have a corresponding Item in this Sequence. Only Dosimetric Objectives which are referenced in the Referenced Dosimetric Objectives Sequence (3010,0071) shall be present in this sequence. Required if any Item in the Referenced Dosimetric Objectives Sequence (3010,0071) references a Dosimetric Objective. One or more Items shall be included in this Sequence. See Section C.36.6.1.6.
>Include Table C.36.2.1.4-1 “Dosimetric Objective Macro Attributes” |
>Referenced Conceptual Volume UID | (3010,000B) | 1C | The UID of the Conceptual Volume in the RT Anatomic Prescription Sequence (3010,0060) to which this Dosimetric Objective applies. Required if the Dosimetric Objective applies to a specific anatomy.
>Dosimetric Objective Evaluation Scope | (3010,0063) | 1 | Whether the Dosimetric Objective is intended to be evaluated over a lifetime scope or only in respect to the current prescriptions. Enumerated Values: CURRENT The Dosimetric Objective applies to the referencing prescriptions. LIFETIME The Dosimetric Objective applies to the referencing prescriptions and accumulated lifetime dose. See Section C.36.6.1.7.

#### C.36.6.1 RT Enhanced Prescription Attribute Descriptions

##### C.36.6.1.1 Therapeutic Role Type Code Sequence

The Therapeutic Role Type Code Sequence (3010,0065) further specifies the role of the anatomy along the Therapeutic Role Category (3010,0064). Table C.36.6-3 describes the codes permitted in the Therapeutic Role Type Code Sequence (3010,0065), when the code used in the Therapeutic Role Category Code Sequence (3010,0064) is as specified.

Table C.36.6-2. Therapeutic Role Type Codes

Code Value of Therapeutic Role Category Sequence (3010,0064) | Context Group for Therapeutic Role Property Type Sequence (3010,0065)
--- | ---
(130041, DCM, "RT Target") | DCID 9534 “Radiotherapy Targets”
(130042, DCM, "RT Dose Calculation Structure") | DCID 9535 “Radiotherapy Dose Calculation Roles”

##### C.36.6.1.2 Conceptual Volume Type Code Sequence

The Conceptual Volume Type Code Sequence (3010,0069) further specifies the type of the anatomy along the Conceptual Volume Category Code Sequence (3010,0067). Table C.36.6-3 describes the codes permitted in the Conceptual Volume Type Code Sequence (3010,0069), when the code used in the Conceptual Volume Type Code Sequence (3010,0069) is as specified.

Table C.36.6-3. Anatomy Property Type Codes

Code Value of Conceptual Volume Category Code Sequence (3010,0067) | Context Group for Conceptual Volume Type Code Sequence (3010,0069)
--- | ---
(123037004, SCT, "Anatomical Structure") | BCID 9514 “Anatomical Structures For Radiotherapy”
(130047, DCM, "External Body Model") | DCID 9507 “External Body Models”
(260787004, SCT, "Physical Object") | BCID 7193 “Physical Object Segmentation Property Types”
(130046, DCM, "Non-specific Volume") | DCID 9508 “Non-specific Volumes”

For code values of the Conceptual Volume Type Code Sequence (3010,0069) not listed in Table C.36.6-3, no Baseline or Defined Context Group is specified.

##### C.36.6.1.3 Conceptual Volume Sequence

The Conceptual Volume Sequence (3010,0025) identifies the Conceptual Volume associated with an RT Anatomy Prescription Item. If the Conceptual Volume is associated with a segment, the segment is defined by the Referenced Segment Reference Index (3010,0020) in the Conceptual Volume Reference Combination and Segmentation Macro (see Section 10.34). Alternatively, the anatomy volume may not (yet) be associated with a segment. For example, an initial prescription may be entered prior to the definition of an organ at risk.

##### C.36.6.1.4 Fraction-based Relationship Sequence

The Fraction-Based Relationship Sequence (3010,0082) is used to specify the relationship between two prescriptions.

The following example shows a treatment performed in 2 phases with a break of 7 days between phases.

In RT Treatment Phase 1, the treatment of Prescription B is intended to start 10 fractions prior to the end of Prescription A.

The Section C.36.7 RT Treatment Phase Intent Module is used to specify the relationship of treatment phases to each other.

Figure C.36.6.1-1. Relationship of Phases and Prescriptions

##### C.36.6.1.5 Parent RT Prescription

The RT Enhanced Prescription Module supports a two-level prescription model (see Figure C.36.6.1-2) in order to document an approach where a high-level prescription is created and then more details may be added. The first level would typically be created during the time of prescription definition with only high-level prescription information based on the RT Physician Intent. The second level, if present, would represent a derived prescription containing more detailed information, such as constraints and objectives. A third or subsequent levels are not permitted.

Figure C.36.6.1-2. Parent and Child RT Prescriptions

##### C.36.6.1.6 Dosimetric Objective Sequence

The Dosimetric Objective Sequence (3010,006C) specifies a set of intended dosimetric goals.

Each item of the Dosimetric Objective Sequence (3010,006C) shall be referenced by at least one item of the Referenced Dosimetric Objectives Sequence (3010,0071) in the current Instance.

Within an RT Physician Intent SOP Instance, a Dosimetric Objective is applicable to all Prescriptions in which the Dosimetric Objective UID (3010,006E) is referenced.

A Dosimetric Objective is intended to be satisfied by the combined effect of all treatments associated with prescriptions that reference the Dosimetric Objective UID (3010,006F).

For example, if there are primary and boost prescriptions that reference the same Dosimetric Objective UID (3010,006E) then the combined effect of both prescriptions is intended to comply with the limit in this Dosimetric Objective.

##### C.36.6.1.7 Dosimetric Objective Evaluation Scope

For Dosimetric Objectives that include a dose value, the value defines the total dose for all fractions of all prescriptions referencing this Dosimetric Objective, and potentially dose from previous treatment, depending on the value of Dosimetric Objective Evaluation Scope (3010,0063).

If Dosimetric Objective Evaluation Scope (3010,0063) has a value of LIFETIME, information from prior treatments shall be included in the evaluation of the Dosimetric Objective.

For example, if an organ has received dose in a prior treatment, and Dosimetric Objective Evaluation Scope (3010,0063) is marked as LIFETIME, then the previously delivered dose shall be included in the evaluation of this objective. Information about prior treatments may be described in Prior Treatment Dose Description (3010,0061) or by Instances referenced by the Prior Treatment Reference Sequence (3010,0062) in RT Prescription Sequence (3010,006B).

If Dosimetric Objective Evaluation Scope (3010,0063) has a value of CURRENT, the objective includes only those prescriptions which reference the same Dosimetric Objective, even if information of a prior treatment is available.

##### C.36.6.1.8 Patient Equipment Relationship Code Sequence

The Patient Equipment Relationship Code Sequence (3010,0030) specifies the orientation of the patient relative to the front of the equipment viewed from the patient support device. For example, in case of the equipment being a gantry, this is the direction from the table (being the patient support device) towards the gantry. In cases where it is not possible to understand unambiguously the direction for a certain equipment, the equipment vendor shall document this direction in its Conformance Statement.

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DICOM PS3.3 2021b - Information Object Definitions