DICOM Second Generation Radiotherapy Objects Part 1 Supplement 147: Physicians Intent and Segment Annotation

DICOM Second Generation Radiotherapy Objects

Part 1

Supplement 147: Physicians Intent and Segment Annotation

Ulrich Busch• Systems Analyst with Varian Medical

Systems• Member of DICOM WG-07 since 2000• Chairman of DICOM WG-07 since 2011• Member of the IHE-RO Technical

Committee since 2005

2DICOM Second Generation Radiotherapy

Christof Schadt• Software Principal with Brainlab AG• Member of DICOM WG-07 since 2005• Vice-Chair DICOM WG-07 since 2011• Member of the IHE-RO Technical

Committee since 2005


Outline

4

Outline• Overview : All of Second Generation• Discuss the particulars of Supplement 147

•Physician Intent •Segment Annotations

• Touch on the Other Supplements that make up Second Generation

• Next steps

DICOM Second Generation Radiotherapy

Introduction

• New Supplements to DICOM Standard

• Defined by manufacturers and clinicians

• Supports and/or influences new technologies and thus new products


DICOM WG-07

• One of the DICOM Standards Committee’s (DSC) Working Groups

• Focus on maintenance and further development of Radiotherapy extensions of the DICOM Standard (“DICOM RT “)

• Current (regular) industry members: Accuray, Brainlab, Elekta, IBA, Mevion, Philips, RaySearch, Varian (and others)


What is DICOM RT?

• DICOM RT is just DICOM

• ‘RT’ indicates the DICOM objects dealing with RT.

• Current release of RT Objects is now known as ”1st Generation RT“ (Gen1)


2nd Generation

• “Second Generation Radiotherapy“• Supplements are about 270 pages• created by DICOM WG-07

• Worked on for over 7 years• Major re-structuring of Gen1 RT objects


Why now 2nd Generation?

9

Introduction – Full RT Second Generation Object Suite• Initial definitions are not

sufficient to describe new technologies

• Use of workflow management will be a focus for the future

• Some definitions needed to be strengthened or restructured for the best utility


Why now 2nd Generation?

Advances in Radiotherapy• Modern Clinical Flow• Continuous Adaptation to accommodate Disease Response• Dynamic Processes need Flexibility in Interoperability

• New Treatment Modalities

• Stronger Capability to represent the Clinical Workflow• Systematic approach for Non-Volumetric and Volumetric Information• Design of Modality-Independent versus Modality-Specific Information

• Electronic Workflow Management

Modernization, Efficiency, Systematics(not handled in this Presentation, e.g. Macros as Building Blocks, Optionality, Use of Latest

Standard Capabilities, Integration of non-RT Objects)

DICOM Second Generation Radiotherapy 10

RT Process Perspective was Too Narrow• 1st Generation:

Result of Treatment Planning System

• 2nd Generation:

Incorporating complete Treatment Workflow

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Focus


2nd Generation Object Overview


RT Course

13

• Represents an RT Treatment Course

• May contain several treatment phases

• Is a container collecting all major objects which are relevant to this course


RT Physicians Intent

14

• Describes how to achieve the curative or palliative therapy

• Total and fractional doses, fractionation schemes, treatment sites, dosimetric objectives and other information is included


Conceptual Volume

15

• Description of an anatomical region or point, which may or may not be associated to one or more volumetric representations


RT Segment Annotation

16

• Represents RT specific annotations on a Segmentation, Surface Segmentation or RT Structure Set


RT Radiation Set

17

• Defines a radiation therapy treatment fraction, through a set of RT Radiations, which may be applied one or more times.

• Now handles newer technologies, and is extensible.


RT Radiation Record

18

• Records actual treatment parameters and attributes

• Now handles newer technologies and is extensible.


RT Dose Image

19

• Represents a 3-dimensional dose distribution using the multi-frame and functional group paradigms.


RT Dose Histogram

20

• Describes a dose-volume histogram

• Based on a volumetric dose calculation

• References a Conceptual Volume and an RT Segment Annotation


RT Dose Samples

21

• Represents dose point data, which are calculated or measured.


RT Treatment Phase

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• A Course can be divided into multiple RT Treatment Phases

• Each Phase represents an attempt to reach a treatment goal via RT Radiation Sets


• Workflow Enabled• Because we have dedicated objects• Still possible to work with or without DICOM

Worklist

• Volatile Information outside objects• Status information• Dynamic Relations

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Solution: Dynamics


• Use new approaches already defined in DICOM

• Volume and Surface Segmentation• Rigid and Deformable Registrations• Some smaller Items (esp. Macros)

• Object-oriented approach• Cohesive objects with different, specific intents• Avoid “Monster” objects, or inappropriate

encapsulation (Plan/RX)

Architectural Principles I


Architectural Principles II

• Flexibility for future expansione.g. open for

• New treatment machines• New segmentation methods• New treatment techniques• New positioning and tracking approaches


Supplement 147 – Prescription and Segment Annotation


DICOM RT Plan Issues

27

DICOM RT Plan

Prescription

Fractionation

Beams

Patient Setup

• Prescription Module is not precisely documented

• Cannot exist outside an RT Plan object

• Does not represent current technologies well

• Links to volatile information (Imaging)


RT Physician Intent

Contains the following parts:• Physician Intent

• Mostly free-text definition of the physician‘s intent based on a diagnosis

• Prescription• Actual prescription parameters

• Treatment Phase Intent• How the time structure of the delivery is intended

• Exists outside of the RT Plan• Supports real-world timing of Prescription information


RT Physician Intent Modules

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IE Module Reference Usage

Include 'RT Second Generation IOD Modules Macro' Table A.VV.1.1.1-1

RT Physician Intent RT Physician Intent C.AA.B1 M

RT Prescription C.AA.B2 U

RT Treatment Phase Intent

C.AA.B3 C

Required if RT Treatment Phase Intent Presence Flag

(30xx,0808) equals YES.


RT Physician Intent Modules


Conceptual Volume (CV)

• Abstract object

• Identifies anatomic region

• May be a combination of other CVs

• Can be utilized without any Segmentation

• Definition can be deferred to later in workflow


Conceptual Volume Modules

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CV Example

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CVol I”Tumor“

RT Structure Set- Region of Interest 1,

“Lesion“

Diagnostic CT

MR

Physician Intent:Prescribe 20Gy to the

tumor.


CV Consistency vs. Change

CV I“Tumor“

RTStructSet 1- ROI 1, “Lesion“

MR CBCT 1

RTStructSet 2- ROI 4, “Target“

CBCT 2

RTStructSet 3-ROI 2, “PTV“

First Day Day 10 Day 2034

CV Combination

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CV I“Lung, left“

CV II“Lung, right“

RT Structure Set- Region of Interest 5,

“Left Lung“

Segmentation Storage-Segment 9,

“Lung, r“

CV III“Lungs“


RT Segment Annotation Modules


RT Segment Annotation

• Separates the RT-specific information from the actual data

• CTV, PTV, OAR, …• Bolus• Density Overrides

• Structure is represented by existing DICOM objects

• Segmentation Storage (3D volume)• Surface Segmentation Storage (3D mesh surface)• RT Structure Set (Contour lines – Gen1)• Others


Other Supplements

• 175 – C-Arm Radiations• 176 – New RT Radiations• 177 – Dose Objects• 178 – RT Course• 179 – RT Explanatory (Part 17)


How does it affect you?

• Once these objects appear, manufacturers will need to support both Gen1 and Gen2 during the transition

• 8 old objects deprecated • 24 new objects added

• The sooner the Gen2 objects are in place, the earlier support for Gen1 can be reduced (or even stopped)


How does it affect you?

• Enhanced Clinical Capability will need Gen2

• Detailed prescription sharing • Prescribed Volumes cross-referenced throughout the clinical

process for tracking and adaptation• Complex or high resolution structure sharing• Highly adaptive positioning or treatment


What will NEMA do to help?

• Provide introduction presentations

• Run hands-on engineering classes in Europe and North America

• Work with IHE-RO to develop the order of adoption for most benefit

• “The Implementer‘s Guide to 2ndGeneration RT Objects“ by WG-07 members


Contact

Stephen VastaghDICOM Secretary NEMA/MITA

[email protected]

Ulrich BuschChairman DICOM WG-07

[email protected]

Christof SchadtVice-Chair DICOM WG-07

[email protected]


Links

• NEMA DICOM Pagehttp://dicom.nema.org

• Participate in DICOMhttp://dicomconference.org/

• DICOM Standard Statushttp://www.dclunie.com/dicom-status/status.html


Thanks to

• Christof, Jim Percy (Elekta), Mike Courtney (Philips), Mark Pepelea (Philips), Bruce Rakes (Mevion) for preparing and reviewing the initial content for an AAPM presentation, on which this is based


Documents

DICOM Second Generation Radiotherapy Objects Part 1 Supplement 147: Physicians Intent and Segment Annotation