DICOM PS3.3 2020b - Information Object Definitions

C.8.8.30 RT Brachy Application Setup Delivery Instruction Module (Current)
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#### C.8.8.30 RT Brachy Application Setup Delivery Instruction Module

The RT Brachy Application Setup Delivery Instruction Module contains additional information required by a Treatment Delivery System (TDS) when specifying delivery of a brachytherapy treatment.

This Module references the RT Plan to be delivered and specifies the treatment tasks to be performed for the Application Setups of the RT Plan.

Figure C.8.8.30-1. Relationship of brachytherapy treatment plan and delivery instruction

The RT Brachy Application Setup Delivery Instruction Module consists of a Sequence of one or more tasks.

Table C.8.8.30-1. RT Brachy Application Setup Delivery Instruction Module Attributes

Attribute Name | Tag | Type | Description
--- | --- | --- | ---
Referenced RT Plan Sequence | (300C,0002) | 1 | Reference to a single RT Plan SOP Instance containing all the brachy application setups and the fraction group referenced in this SOP Instance. Only a single Item shall be included in this Sequence.
>Include Table C.17-3 “Hierarchical SOP Instance Reference Macro Attributes” |
Referenced Fraction Group Number | (300C,0022) | 1 | Indicates which fraction group of the referenced RT Plan in the Referenced RT Plan Sequence (300C,0002) is to be treated in the treatment session.
Current Fraction Number | (3008,0022) | 1 | The index of the fraction that is to be delivered or completed in this treatment session. See Section C.8.8.30.3.
Continuation Pulse Number | (0074,1404) | 1C | The index of the pulse that is to be delivered or completed in this treatment session. Required if Brachy Treatment Type (300A,0202) of the referenced RT Plan in the Referenced RT Plan Sequence (300C,0002) is PDR and if Treatment Delivery Type (300A,00CE) is CONTINUATION in any of the Items in the Brachy Task Sequence (0074,1401). See Section C.8.8.30.4.
Brachy Task Sequence | (0074,1401) | 1 | Specification of Brachy Application Setups to be delivered. One or more Items shall be included in this Sequence. See Section C.8.8.30.1.
>Treatment Delivery Type | (300A,00CE) | 1 | Delivery Type of treatment. Enumerated Values: TREATMENT normal patient treatment CONTINUATION continuation of interrupted treatment See Section C.8.8.30.2.
>Continuation Start Total Reference Air Kerma | (0074,1402) | 1C | Total Reference Air Kermawithin the Application Setup referenced by Referenced Brachy Application Setup Number (300C,000C) at which treatment delivery starts. Required if Delivery Type (300A,00CE) is CONTINUATION.
>Continuation End Total Reference Air Kerma | (0074,1403) | 1C | Total Reference Air Kermawithin the Application Setup referenced by Referenced Brachy Application Setup Number (300C,000C) at which treatment delivery ends. Required if Delivery Type (300A,00CE) is CONTINUATION.
>Referenced Brachy Application Setup Number | (300C,000C) | 1 | Brachy Application Setup Number (300A,0234) within Brachy Application Setup Sequence (300A,0230) in the referenced RT Plan. One or more Items shall be included in this Sequence.
>Channel Delivery Order Sequence | (0074,1405) | 3 | The order in which the channels are to be delivered. One or more Items are permitted in this Sequence.
>>Referenced Channel Number | (0074,1406) | 1 | The channel to be delivered, specified by the value of Channel Number (300A,0282) in referenced RT Plan.
>>Channel Delivery Order Index | (0074,140C) | 1 | The order of delivery of this channel, monotonically increasing by 1, starting from 1, where number 1 is the first channel to be delivered.
>Channel Delivery Continuation Sequence | (0074,140D) | 1C | The treatment time weights for channels to be delivered to complete a previously interrupted fraction. Required if Delivery Type (300A,00CE) is CONTINUATION. One or more Items shall be included in this Sequence.
>>Referenced Channel Number | (0074,1406) | 1 | The channel to be delivered, specified by the value of Channel Number (300A,0282) in referenced RT Plan.
>>Start Cumulative Time Weight | (0074,1407) | 1 | Cumulative Time Weight where to start/continue the delivery of the referenced channel. See Section C.8.8.15.6.
>>End Cumulative Time Weight | (0074,1408) | 1 | Cumulative Time Weight where to stop the delivery of the referenced channel. See Section C.8.8.15.6.
Omitted Application Setup Sequence | (0074,140E) | 1C | Application Setups of the current RT Plan containing channels not to be delivered. Required if Delivery Type (300A,00CE) is CONTINUATION and one or more channels of any Application Setup are omitted. One or more Items shall be included in this Sequence.
>Referenced Brachy Application Setup Number | (300C,000C) | 1 | Brachy Application Setup Number (300A,0234) within Brachy Application Setup Sequence (300A,0230) in referenced RT Plan.
>Omitted Channel Sequence | (0074,1409) | 1 | Channels defined for this Application Setup not to be delivered. One or more Items shall be included in this Sequence.
>>Referenced Channel Number | (0074,1406) | 1 | Channel to be omitted, specified by the value of Channel Number (300A,0282) in the referenced RT Plan.
>>Reason for Channel Omission | (0074,140A) | 1 | Reason why the referenced channel is not to be delivered. Defined Terms: ALREADY_TREATED The channel has been already delivered. OTHER This channel is not to be delivered for other reasons.
>>Reason for Channel Omission Description | (0074,140B) | 3 | Description of reason for omission.

##### C.8.8.30.1 Brachy Task Sequence

The Brachy Task Sequence (0074,1401) contains instructions for the delivery of a single treatment session. A treatment session is the time that the patient is connected to the treatment delivery system. During a treatment session, one fraction of the referenced plan is delivered. If the value of Brachy Treatment Type (300A,0202) in the reference RT Plan is HDR, the entire fraction is delivered at one time. If the value is PDR, the fraction is divided into a number of pulses which are delivered periodically during the treatment session.

The Application Setup groups together the channels to be delivered. The task Sequence can also contain the delivery order of the channels. The Omitted Application Setup Sequence (0074,140E) contains the channels to skip in the case of continuation of an interrupted treatment.

Figure C.8.8.30-2. Relation of the Fraction, Pulse and Channels within the RT Brachy Task Sequence

The following scenarios demonstrate the usage of the RT Brachy Application Setup Delivery Instruction Module for the Treatment Management System (TMS) to instruct the Treatment Delivery System (TDS) to initiate brachytherapy treatment and continue an interrupted delivery.

###### C.8.8.30.1.1 Usage Scenario 1: HDR Treatment, Interruption Skipping Remainder of the Interrupted Delivery

Brachytherapy plan overview:

- Plan1, HDR, 2 fractions;

- Channel1, two dwell positions, 10 sec + 10 sec

- Channel2, two dwell positions, 10 sec + 10 sec

Treatment session 1:

- Treatment Management System (TMS):

  - Requests the delivery of the first fraction of the plan:

  - RT Brachy Application Setup Delivery Instruction:

    - Referenced RT Plan Sequence (300C,0002) = UID of "Plan1"

    - Referenced Fraction Group Number (300C,0022) = 1

    - Current Fraction Number (3008,0022) = 1

    - Brachy Task Sequence (0074,1401):

      - Treatment Delivery Type (300A,00CE) = TREATMENT

      - Referenced Brachy Application Setup Number (300C,000C) = 1

- Treatment Delivery System (TDS):

  - Delivers the first fraction and returns a RT Brachy Treatment Record that describes interruption at channel 2 after 9 seconds of the second dwell position is being delivered.

Treatment session 2:

- It has been decided to proceed to fraction 2 without delivering the remainder of fraction 1. This is not a continuation case.

- Treatment Management System (TMS):

  - Requests the delivery of the second fraction of the plan:

  - RT Brachy Application Setup Delivery Instruction:

    - Referenced RT Plan Sequence (300C,0002) = UID of "Plan1"

    - Referenced Fraction Group Number (300C,0022) = 1

    - Current Fraction Number (3008,0022) = 2

    - Brachy Task Sequence (0074,1401):

      - Treatment Delivery Type (300A,00CE) = TREATMENT

      - Referenced Brachy Application Setup Number (300C,000C) = 1

- Treatment Delivery System (TDS) :

  - Delivers the second fraction and returns a RT Brachy Treatment Record that describes a complete delivery of that fraction.

###### C.8.8.30.1.2 Usage Scenario 2: PDR Treatment, Interruption and Continuation

Brachytherapy plan overview:

- Plan2, PDR, 10 pulses;

- Channel1, two dwell positions, 50 sec + 50 sec

- Channel2, two dwell positions, 50 sec + 50 sec

Treatment Session 1

- Treatment Management System (TMS):

  - Requests the delivery of the first fraction of the plan:

  - RT Brachy Application Setup Delivery Instructions:

    - Referenced RT Plan Sequence (300C,0002) = UID of "Plan2"

    - Referenced Fraction Group Number (300C,0022) = 1

    - Current Fraction Number (3008,0022) = 1

    - Brachy Task Sequence (0074,1401):

      - Treatment Delivery Type (300A,00CE) = TREATMENT

      - Referenced Brachy Application Setup Number (300C,000C) = 1

- Treatment Delivery System (TDS) :

  - Delivers the first fraction and returns a RT Brachy Treatment Record that that describes interruption at pulse 5 of the first fraction at channel 2, after 25 seconds of the first dwell position was delivered. Total Reference Air Kerma Delivered was 100.

Treatment Session 2

- It has been decided to proceed to fraction 2 to deliver the remainder of the interrupted plan as instructed by the following task transmitted inside the delivery instruction:

- The remainder is defined as to skip 25 sec of the first dwell position of channel 2 and continue with the second dwell position.

- Treatment Management System (TMS):

  - Requests the continuation of the delivery of the first fraction of the plan:

  - - Referenced RT Plan Sequence (300C,0002) = UID of "Plan2"

    - Referenced Fraction Group Number (300C,0022) = 1

    - Current Fraction Number (3008,0022) = 1

    - Continuation Pulse Number (0074,1404) = 5

    - Brachy Task Sequence (0074,1401):

      - Treatment Delivery Type (300A,00CE) = CONTINUATION

      - Continuation Start Total Reference Air Kerma (0074,1402) = 100

      - Continuation End Total Reference Air Kerma (0074,1403) = 1000

      - Referenced Brachy Application Setup Number (300C,000C) = 1

      - Channel Delivery Order Sequence (0074,1405):

        - Referenced Channel Number (0074,1406) = 2

        - Channel Delivery Order Index (0074,140C) = 1

      - Channel Delivery Continuation Sequence (0074,140D):

        - Referenced Channel Number (0074,1406) =2

        - Start Cumulative Time Weight (0074,1407) = 50

        - End Cumulative Time Weight (0074,1408) = 100

    - Omitted Application Setup Sequence (0074,140E):

      - Referenced Brachy Application Setup Number (300C,000C) = 1

      - Omitted Channel Sequence (0074,1409):

        - Referenced Channel Number (0074,1406) = 1

        - Reason for Channel Omission (0074,140A) = ALREADY_TREATED

- Treatment Delivery System (TDS):

  - Delivers the first fraction and returns RT Brachy Treatment Record that describes that the treatment first fraction was continued and the reminder was delivered fully (including the rest of the pulses from 6-10).

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DICOM PS3.3 2020b - Information Object Definitions