1. DICOM Second Generation Radiotherapy Objects Part 1
Supplement 147: Physicians Intent and Segment Annotation
We are here to present the first public information of the DICOM Second Generation Radiotherapy Objects. These objects are being submitted and reviewed by the DICOM Working Group over 6 supplements. The first to be approved for public comment is Supplement 147, which covers Physicians Intent and Segment Annotations.
The others –
175
Second Generation Radiotherapy – C-Arm Radiations
176
Second Generation Radiotherapy – New RT Radiations
177
Second Generation Radiotherapy – Dose Objects
178
Second Generation Radiotherapy – RT Course
179
Second Generation Radiotherapy – RT Explanatory (Part 17)

2. 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
Uli has a long history with DICOM, and is currently the Chairman of DICOM Working Group 7, the RT group under DICOM.
DICOM Second Generation Radiotherapy

3. 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
Christof Schadt is the Vice-Chair of Working Group 7, and his company has already made some exploratory efforts at implementing some of the Second Genration objects.
DICOM Second Generation Radiotherapy

4. Outline 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
Today, we will cover the following topics:
a very cursory overview of the Second Generation Objects as a group
Discuss the particulars of the first supplement
Touch on the other supplements
Next steps
Our goals are to give a varied audience some of their first introduction to these items, to give some time for questions and reactions, and to help guide any general ideas on how implementation may proceed and what value it would have.
DICOM Second Generation Radiotherapy

5. Introduction New Supplements to DICOM Standard
Defined by manufacturers and clinicians
Supports and/or influences new technologies and thus new products
The DICOM Second Generation objects are described in a series of supplements to the DICOM standard. They are the outcome of a long effort by manufacturers and clinicians from many RT companies and clinical sites. In a broad generalization, the Second Generation objects support old and new RT technology and approaches, more strongly supports workflow, and implements an extensible framework to allow future technologies to operate with DICOM RT
DICOM Second Generation Radiotherapy

6. DICOM Second Generation Radiotherapy
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)
Introduction to „who is DICOM WG-07“
Explain main work
DICOM Second Generation Radiotherapy

7. DICOM Second Generation Radiotherapy
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)
Talk to slide…indicate that the DICOM RT label has stuck because the first RT specific objects were introduced through one large supplement. In fact, RT uses, and has proposed objects that are used by other disciplines, such as CT Image and Segmentations. There is no “wall” between RT objects and other DICOM objects.
DICOM Second Generation Radiotherapy

8. DICOM 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
DICOM Second Generation Radiotherapy

9. Why now 2nd Generation?
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
Explain in general what this talk is about (no details)
DICOM Second Generation Radiotherapy

10. DICOM Second Generation Radiotherapy
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)
New Treatment Techniques:
Adaptive radiotherapy
Tomotherapeutic treatments
New Treatment Machines:
Non-isocentric machines
Robotic machines
Additional degrees of freedom
New positioning techniques
Positioning as of today is an integral part of treatment (currently not really reflected in 1G)
For all of this Workflow Management could be used to prevent manual errors.
The use of current DICOM RT is widespread and growing exponentially so now does not seem like a good time to restart.
The practice of Radiation Therapy has advanced over the life of the RT part of the standard and there are key things we can not do, or do well, with the current set of DICOM objects:
Prescriptions can not be adequately defined and transferred unambiguously with useful content from one system to another.
Adaptive planning : DICOM data that belongs together is not easy to gather and consolidated. We have to make assumptions about the use of DIOM Series and Studies. Ever changing structures and updating treatments are inefficient to create and difficult to track in the current standard. The progress of an adapted set of organ definitions or treatments is clumsy, if not impossible, to track with the large contour and plan models we have in the first generation. The form of these objects were what was intended but we now need to break them apart so that we can keep data that is not changing separate from that which is and provide the referencing that will allow us to track prescription, patient or plan modifications over time.
Complex 3D objects are difficult to encode as 2D contours and can be ambiguous about the meaning of their contours (eg donut shapes).
New types of non-isocentric machines cannot be accommodated in the current isocentric C-Arm Linac model; for example, Tomotherapy, GammaKnife, CyberKnife
The current status of a patient model or treatment, whether it is pending approval, under treatment or done with treatment could not be tracked easily in the DICOM objects. By removing the state of an object from its content we don’t have to update and create new DICOM objects every time it changes from new to approved, for example; likewise, we don’t then have to update objects that reference that one.
As has happened in other DICOM areas like Radiology, DICOM services like Unified Procedure Step have come into play where orders can be placed, orders can be acknowledged and procedures can be reported back to a central authority in the enterprise. DICOM 2nd generation anticipates this and builds this into the assumptions for the new data objects.
DICOM Second Generation Radiotherapy

11. DICOM Second Generation Radiotherapy
Focus
RT Process Perspective was Too Narrow
1st Generation:
Result of Treatment Planning System
2nd Generation:
Incorporating complete Treatment Workflow
One other way to view the transition…
DICOM Second Generation Radiotherapy

12. 2nd Generation Object Overview
DICOM Second Generation Radiotherapy

13. RT Course Represents an RT Treatment Course
May contain several treatment phases
Is a container collecting all major objects which are relevant to this course
Try to limit discussion on this.
DICOM Second Generation Radiotherapy

14. DICOM Second Generation Radiotherapy
RT Physicians Intent
Describes how to achieve the curative or palliative therapy
Total and fractional doses, fractionation schemes, treatment sites, dosimetric objectives and other information is included
We will get into more detail in this presentation.
DICOM Second Generation Radiotherapy

15. DICOM Second Generation Radiotherapy
Conceptual Volume
Description of an anatomical region or point, which may or may not be associated to one or more volumetric representations
Also in this presentation….
DICOM Second Generation Radiotherapy

16. DICOM Second Generation Radiotherapy
RT Segment Annotation
Represents RT specific annotations on a Segmentation, Surface Segmentation or RT Structure Set
In this presentation.
DICOM Second Generation Radiotherapy

17. RT Radiation Set
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.
DICOM Second Generation Radiotherapy

18. RT Radiation Record Records actual treatment parameters and attributes
Now handles newer technologies and is extensible.
DICOM Second Generation Radiotherapy

19. RT Dose Image
Represents a 3-dimensional dose distribution using the multi-frame and functional group paradigms.
DICOM Second Generation Radiotherapy

20. RT Dose Histogram Describes a dose-volume histogram
Based on a volumetric dose calculation
References a Conceptual Volume and an RT Segment Annotation
DICOM Second Generation Radiotherapy

21. RT Dose Samples
Represents dose point data, which are calculated or measured.
DICOM Second Generation Radiotherapy

22. RT Treatment Phase
A Course can be divided into multiple RT Treatment Phases
Each Phase represents an attempt to reach a treatment goal via RT Radiation Sets
DICOM Second Generation Radiotherapy

23. Solution: Dynamics Workflow Enabled
Because we have dedicated objects
Still possible to work with or without DICOM Worklist
Volatile Information outside objects
Status information
Dynamic Relations
Addressed By UPS and usage of RT Course IOD
(Companion objects?)
DICOM Second Generation Radiotherapy

24. Architectural Principles I
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)
New approaches:
Now there are lots of things to build on top
Contrary to 1G, where there mainly were images
OO:
Reduce to what is really necessary
Factor out separate capabilites
DICOM Second Generation Radiotherapy

25. Architectural Principles II
Flexibility for future expansion e.g. open for
New treatment machines
New segmentation methods
New treatment techniques
New positioning and tracking approaches
DICOM Second Generation Radiotherapy

26. Supplement 147 – Prescription and Segment Annotation
DICOM Second Generation Radiotherapy

27. DICOM RT Plan Issues Prescription Module is not precisely documented
Cannot exist outside an RT Plan object
Does not represent current technologies well
Links to volatile information (Imaging)
Prescription
Fractionation
Beams
Patient Setup
DICOM Second Generation Radiotherapy

28. 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
overall intent of the treatment.
mostly descriptive text
freely formulated advice
prescription(s) for a specific target.
Treatment phases define the intended time structure of the prescribed treatment
(Question: how will the legacy Rx information and objects be handled?)
DICOM Second Generation Radiotherapy

29. RT Physician Intent ModulesIE
Module
Reference
Usage
Include 'RT Second Generation IOD Modules Macro' Table A.VV
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.
overall intent of the treatment.
mostly descriptive text
freely formulated advice
prescription(s) for a specific target.
Treatment phases define the intended time structure of the prescribed treatment
DICOM Second Generation Radiotherapy

30. RT Physician Intent Modules
overall intent of the treatment.
mostly descriptive text
freely formulated advice
prescription(s) for a specific target.
Treatment phases define the intended time structure of the prescribed treatment
The intent module is more “free form”.. The prescription module now ties specifics to conceptual volumes, which may or may not be related to segmented volumes…
Treatment phase describes the time frame and fractionation
Diagram B is the Conceptual Volume reference
DICOM Second Generation Radiotherapy

31. 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
DICOM Second Generation Radiotherapy

32. Conceptual Volume Modules

33. Prescribe 20Gy to the tumor.
CV Example
Diagnostic CT
CVol I
”Tumor“
Physician Intent:
Prescribe 20Gy to the tumor.
RT Structure Set
- Region of Interest 1, “Lesion“
Physician reviews a diagnostic CT, with a Tumor volume.
Generically, first prescribes 20Gy….
An MR is ordered, and separately this is used to Segment a “Lesion” structure, to which the Conceptual Volume is linked MR
DICOM Second Generation Radiotherapy

34. CV Consistency vs. Change
CV I
“Tumor“
RTStructSet 1
- ROI 1, “Lesion“
RTStructSet 2
- ROI 4, “Target“
RTStructSet 3
ROI 2,
“PTV“
Adaptive!
In this example treatment begins, but further refinement to the treatment occurs. Using cone beam CTs as a basis, further volumes are defined and given treatment parameters. MR
CBCT 1
CBCT 2
First Day
Day 10
Day 20

35. CV Combination CV I “Lung, left“ CV II “Lung, right“ CV III “Lungs“
Another example: it’s anticipated that CVs can be handled in abstract in single and in group references…with different modalities supplying the underlying data that allows linkage to a specific segmentation.
RT Structure Set
- Region of Interest 5, “Left Lung“
Segmentation Storage
Segment 9,
“Lung, r“
DICOM Second Generation Radiotherapy

36. RT Segment Annotation Modules
“Removes… “- e.g. clinical target volume, organ at risk, bolus, density overrides
„What is it“ vs. „What does it mean“
DICOM Second Generation Radiotherapy

37. 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
“Removes… “- e.g. clinical target volume, organ at risk, bolus, density overrides
„What is it“ vs. „What does it mean“
DICOM Second Generation Radiotherapy

38. Other Supplements 175 – C-Arm Radiations 176 – New RT Radiations
177 – Dose Objects
178 – RT Course
179 – RT Explanatory (Part 17)
“Removes… “- e.g. clinical target volume, organ at risk, bolus, density overrides
„What is it“ vs. „What does it mean“
DICOM Second Generation Radiotherapy

39. 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)
RT Dose
RT Structure Set
RT Image
RT Plan
RT Beams Treatment Record
RT Brachy Treatment Record
RT Treatment Summary Record
RT Ion Plan
RT Ion Beams Treatment Record
DICOM Second Generation Radiotherapy

40. 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
DICOM Second Generation Radiotherapy

41. 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
DICOM Second Generation Radiotherapy

42. Contact Stephen Vastagh Ulrich Busch Christof Schadt
DICOM Secretary NEMA/MITA
Ulrich Busch
Chairman DICOM WG-07
Christof Schadt
Vice-Chair DICOM WG-07
DICOM Second Generation Radiotherapy

43. Links NEMA DICOM Page Participate in DICOM DICOM Standard Status
Participate in DICOM
DICOM Standard Status
DICOM Second Generation Radiotherapy

44. 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
DICOM Second Generation Radiotherapy