MINUTES
Sub-group on Ion Therapy
Of DICOM’s Working Group Seven
Elekta Office, Sunnyvale, CA
January 20 – 21, 2010
Members Present
Elekta
Moyers, Michael
Philips Healthcare
Varian
Represented by
Stuart Swerdloff
Michael Moyers (Consultant)
Mark Pepelea
Paivi Tuhkanen
Members Absent
Kooy, Hanne
Newman, Michael
Nucletron Scandanavia
RaySearch Laboratories
Siemens Healthcare
Represented by
Hanne Kooy (Massachusetts General Hospital)
Michael Neumann (Inst. for Clinical Biochemistry and
PathobioChemistry)
Nina Tilly
Anders Murman
Claus-Peter Hoeppner
Others Present
Scott Mitchell
Oliver Vierlinck
David Wikler
Howard Clark
Associated with
Elekta
IBA Particle Therapy
IBA Particle Therapy
MITA
Presiding Officer:
Stuart Swerdloff, Chair
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Ion Therapy Sub-group of DICOM’s
Working Group Seven (Radiotherapy)
January 20 – 21, 2011
1. Administrative Details
WG-07-Ion Chair Pro-Tem Stuart Swerdloff called the meeting to order at 9:00 a.m. on January
20, 2011.
Participants identified themselves and their employers. The secretary noted that a quorum was
not present.
The agenda was modified to include a discussion of CP1013, a review of minutes from previous
meetings, and election of a chair.
As this was the first face-to-face meeting since the group was revitalized in August of 2010, the
secretary presented minutes from each of the following Tcons:
 August 4, 2010
 September 1, 2010
 September 14, 2010
 October 19, 2010
 November 23, 2010
All were approved as presented.
The secretary confirmed the desirability of conducting an election for an official chair of the subgroup, since it now fully engaged in developing a new supplement to the DICOM Standard.
Chair Pro-tem Stuart Swerdloff offered to continue as chair if that was the will of the members.
The secretary asked if there might be any other volunteers or nominations. As none were
forthcoming, Mr. Swerdloff was elected by affirmation.
The chair noted that one of the key resources for this meeting was the Split-out of Ion Therapy
material from Draft Supplement 147. A copy of that document may be found in the Minutes
Folder for the Tcon on October 19, 2010, which is located at:
FTP://medical.nema.org/MEDICAL/Dicom/Minutes/WG-07-ION/2010-10-19_Tcon
2. CP1013
After a three-hour discussion of CP1013, members agreed to remove from the CP that portion of
the text concerned with the Number of Scan Spot Positions in the RT Ion Beams Session
Module.
Members also engaged in a detailed discussion of the definition of “Delivered Scan Spot
Delivery Order Map.” Some wondered whether it could be made a Type 1C rather than a Type 3
if the delivery order were modified by the delivery device. After some discussion, and
particularly in view of safety considerations, they voted (with one abstention – Michael Moyers),
to remove this topic from CP1013.
At this point, it was clear that the CP needed either to be withdrawn or subjected to major
modifications. The following reasons were articulated and transmitted to the WG-07 member
who was planning to present it to WG-06 the following week:
1) Redefining Number of Scan Spot Positions in RT Ion Beams Session module alters the
expected values elsewhere (Scan Spot Position Map, Scan Spot Meterset). A redefinition
should be placed in the Attribute Description, and not just in a definitions section. Good
reason to go back to WG7 for review/approval.
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Ion Therapy Sub-group of DICOM’s
Working Group Seven (Radiotherapy)
January 20 – 21, 2011
2) Redefining Number of Scan Spot Positions can result in having zero spots delivered in
previously delivered Ion Control Points, and the maps which are 1C are now empty (an
inconsistency). Good reason to not have this in the CP (it can't be changed without
breaking the SOP Class and/or existing implementations)
3) Zero filling (previous delivery) and Zero padding (undelivered) of spot meterset is
unnecessary if Number of Scan Spot Positions is redefined (as proposed). If Number of
Scan Spot Positions is *not* redefined, then zero filling/zero padding as a clarification is
ok. The constructor of the Treatment Record is responsible for manipulating the data to
fit in to the defined construct (Number of Scan Spot Positions in the plan, regardless of
any potential multiple spot deliveries intended in the plan for one spot, i.e. if multiple
delivered spots were actually delivered which were intended for one planned spot, one
coordinate value must be provided for the corresponding Scan Spot Position Map entry).
The last spot delivered may have non-zero meterset that should not be considered as
complete delivery or complete lack of delivery to the spot. An interrupted spot must be
accounted for with a non-zero value.
4) Specification of type 3 Scan Spot Energy Map and Delivered Scan Spot Energy Map
results in a Hazard due to specification. A delivery using previously conformant
implementations could result in misadministration and no record of that
misadministration.
5) The wording describing conditionality of behavior regarding zero filling/zero padding
(according to the CP v04) with respect to the presence of the Delivered Scan Spot
Delivery Order Map element indicates that one can (according to the CP v04) list only
those spots delivered in the current session. If one does this for spots that were
previously delivered (not the current session), the possibility exists to provide no values
in the Delivered Scan Spot Meterset map (or Scan Spot Position Map) for those spots not
delivered. Those elements are type 1C, and it would break conformance to encode
nothing. So the wording regarding "and Delivered Scan Spot Delivery Order is not
encoded" should be struck. One must always do zero fill and zero pad as described
regardless of the presence of Delivered Scan Spot Delivery Order Map. The Delivered
Scan Spot Delivery Order Map is still desired, only the description of the conditional
behavior regarding zero filling/padding should be struck.
3. Gaps in the Current RT Ion Plan
Members listed the following examples of gaps in the current RT Ion Plan. They include
 RecordedIonWedge (There is only Recorded Wedge). It should have
IsoCenterToWedgeTrayDistance.
 Uniform Scanning: Scan Field Size X, Scan Field Size Y, Recorded/Delivered Scan Field
Size X and Y.
 Physical Dose Rate (Not Meterset Rate; members wondered why IBA believes this may
be necessary).
 Is the Referenced RT Plan Sequence type 2 or type 3? Since the Referenced Beam
Number is type 1, what does one refer to if the Plan isn't referenced?
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_____________________________
Ion Therapy Sub-group of DICOM’s
Working Group Seven (Radiotherapy)
January 20 – 21, 2011
4. Proposed Additions to RT Ion Plan
Michael Moyers suggested the addition of three new attributes to address organ motion in the Ion
Beam Delivery Device Module. These were named:
 Motion Mitigation Techniques
 Painting Characteristics
 Recorded Beam Tracking Offset Map
Members noted that information about motion signal is needed to correlate to actual patient
motion. If we moved something, where was the patient anatomy at the time, and where did the
beam end up in the patient? There is a need for clear separation of the Plan side (to tell the
machine where it will get its signal from) and the Record side (to enable dose reconstruction
and/or delivery continuation). Time information is also required for motion mitigation activities
(e.g., start time/end time). How are respiratory cycle phases utilized in Beam On vs. Beam Off?
5. Other Topics
As the meeting proceeded, the discussion touched on each of the following topics:
 Ion Applicator vs. Snout vs. Applicator Carriage. Precise definitions are needed.
C.8.14.12 (referred to by Applicator section) is missing in PS 3.3 (2009/2008/2004). A
CP might be useful here.
 Snout/Applicator tend to be confounded/combined in current implementations. (No
Applicators of ION_xxx type found in current RT Ion Plan objects).
 Corrections regarding Multi Leaf Collimator (MLC). (e.g., VSAD issues/formula error;
noting that distance from IsoCenter to Device is different from conventional.)
 Ion Classes. A better name is needed.
 Drilling bit size (milling tool diameter) for blocks, not just compensators.
 Inclusion of margin information for re-planning and milling purposes (e.g. CTV to
Aperture edge distance/margin). This could be a TPS responsibility or a Milling device
responsibility.
 Spot meterset tolerances (e.g. Poisson statistics or machine limitations). Tolerances for
all devices and settings specific to Ion therapy, which the clinician may wish to vary from
beam to beam or patient to patient. What does one do with this tolerance?
 Defining differing types of Patient Support with their own parameters, rather than
attempting to do so in terms of the traditional couch. Collaborate with IEC regarding
parameters. Coordinate with Christof Schadt's effort.
 Definition of Support angle being different from Imaging/Sim patient support angle.
Need to address systematic rotation correction separate from prescribed rotation.
 Embed Patient Coordinate System on top of Table Top Coordinate System. This comes
up in specific with dynamic re-projection of DRRs vs. the CT. The ultimate expression is
4x4 relationship between Beamline reference frame and Patient Coordinate System
reference frame. (IEC is Yaw, then Pitch, then Roll).
 Organ Motion: Phase Shifting/Gating, alternative spot patterns, etc. Need a record of
what was done for Organ motion/gating. Timing information? Phase information?
 Finer grain of control for various spot parameters.
 High-level use cases -e.g.:
o Prescription (BED?) (Physician Level, e.g. Physician Intent)
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Ion Therapy Sub-group of DICOM’s
Working Group Seven (Radiotherapy)
January 20 – 21, 2011


o Immobilization and initial imaging, including 4D imaging
o Planning
o Device Fabrication
o QA
o Patient Position Verification
o Treatment Delivery (Motion Management/Mitigation? or Tuning?)
o Continuation of Interruption (from Treatment Record)
o Dose calculation from delivery information (Treatment Record, BED?)
o Potential re-planning.
o Sending data to RTOG for comparisons (BED? Physical Dose?)
Discussion of Spot Tune ID. Significant disagreement regarding requirement for it and
its implications. Is there common interpretation among machine vendors regarding what
correlates (DICOM elements) are affected/constrained by the value of Spot Tune ID?
There is a need to get machine vendors to attempt to come to common agreement
regarding Spot Tune ID (or equivalent).
Proposal for 2nd SOP Class that takes an alternative perspective on responsibility for
incorporation of detailed machine information. TPS specifying desired parameters
instead of machine settings.
6. Action Items


The secretary will explore the availability of rooms at NEMA and ASTRO for a meeting
on June 20 – 24, 2011.
Stuart Swerdloff will alert Uli Busch of the group’s decision regarding CP1013.
7. New Business
No new business was introduced at this meeting.
8. Next WG-07 Ion Therapy Meeting
A one-hour Web-enhanced Tcon will be held on February 10, 2011 beginning at:
 9 p.m. CET
 3 p.m. EST
 12 p.m. PST
 9 a.m. in New Zealand
A two hour web-enhanced Tcon will be held on March 15, 2011 at:
 5 p.m. CET
 11 a.m. EST
 8 a.m. PST
 5 a.m. in New Zealand
9. Adjournment
The meeting was adjourned at 5:40 p.m. PST.
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_____________________________
Ion Therapy Sub-group of DICOM’s
Working Group Seven (Radiotherapy)
January 20 – 21, 2011
Reported by:
Howard Clark, Secretary
February 8, 2011
Reviewed by counsel:
February 9, 2011
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_____________________________
Ion Therapy Sub-group of DICOM’s
Working Group Seven (Radiotherapy)
January 20 – 21, 2011