DICOM%20Anniversary%20Conference%20Experience%20Using%20DICOM-RT%20Objects%20for%20Clinical%20Trials%20QA - PowerPoint PPT Presentation

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DICOM%20Anniversary%20Conference%20Experience%20Using%20DICOM-RT%20Objects%20for%20Clinical%20Trials%20QA

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Title: DICOM%20Anniversary%20Conference%20Experience%20Using%20DICOM-RT%20Objects%20for%20Clinical%20Trials%20QA


1
DICOM Anniversary ConferenceExperience Using
DICOM-RTObjects for Clinical Trials QA
  • Walter R. Bosch, D.Sc., John W. Matthews, D.Sc.,
  • Vincent A. Frouhar, Ph.D., Jatinder R. Palta,
    Ph.D.,
  • James A. Purdy, Ph.D.

2
NCI Advanced Technology QA Consortium
  • Members
  • Image-guided Therapy Center (ITC)
  • J. Purdy, W. Bosch, J. Matthews, Wm. Straube, J.
    Michalski
  • Resource Center for Emerging Technologies (RCET)
  • J. Palta, V. Frouhar, J. Dempsey
  • Radiological Physics Center (RPC)
  • G. Ibbott, D. Followill
  • Radiation Therapy Oncology Group (RTOG)
  • E. Martin, R. Lustig
  • Quality Assurance Review Center (QARC)
  • T.J. FitzGerald, M. Urie, K. Ulin
  • Support
  • NIH U24 grant CA81647, Advanced Technology QA
    Center

3
NCI Advanced-Technology QA Consortium
  • History
  • Created in 2002 (in its current form) by NCI to
    support QA for advanced technology clinical
    trials (P.I. J.A. Purdy, Ph.D.)
  • Builds on a decade of experience in supporting QA
    for clinical trials involving 3DCRT and IMRT
  • Mission
  • Develop appropriate and uniform QA procedures and
    criteria
  • Facilitate sharing of developmental and QA
    resources for digital data submission and review

4
Dose-Response Modeling in Radiotherapy
  • Fundamental trade-off
  • deliver tumoricidal dose to a target
  • avoid injury to radiosensitive normal tissues
    (organs at risk)
  • Normal-tissue tolerance doses in current use are
    based on simple point doses and do not account
    for dose-volume effects.
  • Correlating volumetric doses with clinical
    outcomes is expected to yield better
    dose-response models for normal tissue.

5
Digital Data for Advanced-Technology Clinical
Trials in Radiotherapy
  • Primary data (volumetric dosimetry)
  • Volumetric Image (CT)
  • Structure Set GTV, CTV, PTV, OAR
  • 3-D Dose Distribution (including fractionation
    information)
  • Secondary data (QA of primary data)
  • Treatment Plan Specification
  • Dose-Volume Histograms
  • Digital Simulator and Portal Images

6
Digital Data Submission for Advanced-Technology
Clinical Trials
  • Treatment planning data are stored in proprietary
    formats.
  • For meaningful exchange of information, we need a
    common data representation and interchange
    format.
  • RTOG Data Exchange Format
  • Based on AAPM Report 10
  • Used to exchange of treatment planning data in
    RTOG advanced technology protocols, starting in
    1994.
  • Over 1600 protocol data sets submitted to date.

7
RTOG Advanced-Technology Protocols
RTOG Protocol Site Status Approved Institutions Accrued Cases
9406 Prostate Ph I/II Closed 53 1084
9311 Lung Ph I/II Closed 26 180
9803 Brain (GBM) Ph I/II Closed 46 210
H-0022 Oropharynx IMRT Ph I/II Open 13 25
H-0225 Nasopharynx IMRT Ph II Open 13 2
L-0117 Lung Ph I/II Open 34 14
P-0126 Prostate Ph III Open 79 146
P-0232 Prostate Brachytherapy Ph III Open 5 0
BR-0319 Breast Ph I/II Open 8/15 0 0
as of 9/16/2003
8
Why Use DICOM to Represent Radiotherapy Treatment
Planning Information?
  • Broadly-based industry standard
  • Support for current and future imaging and
    treatment modalities
  • PET
  • Functional MRI
  • External beam IMRT
  • HDR brachytherapy
  • Heavy-particle therapy

9
History of the DICOM RT Objects
  • November 1994 DICOM Ad Hoc Committee on
    Radiotherapy Objects met at RSNA
  • June 1997 Supplement 11 approved
  • RT Structure Set
  • RT Plan
  • RT Dose
  • RT Image
  • May 1999 Supplement 29 approved
  • RT Treatment Record

10
DICOM RT Objects Needed for Advanced Technology
Clinical Trials
  • A participant must submit a complete,
    protocol-compliant data set CT Image (MR Image,
    US Image), RT Structure Set, RT Dose, RT Plan,
    and RT Image.
  • Many clinical implementations support only a
    subset of the RT objects. Typical external-beam
    TPS
  • Only recently have commercial treatment planning
    systems begun to export this complete set of
    objects.

11
Special Requirements for DICOM Attributes for
Clinical Trials
  • Type 3 attributes may not be present.
  • Not meaningful in all applications
  • Incompletely specified objects at early stages of
    the planning process
  • Special requirements for attributes values, e.g.,
  • RT Plan Geometry (300A,000C) must be PATIENT.
  • CT and MR images must have square pixels.
  • The ATC Fileset Reader application Conformance
    Statement (http//itc.wustl.edu) lists required
    attributes and special requirements for attribute
    values.

12
RT Dose Object Implementation Issues
  • Single, multi-frame dose object vs. many, planar
    dose objects
  • Grid Frame Offset Vector
  • Absolute axial coordinate of dose grid plane
  • Relative offset of dose grid plane from Image
    Position (Patient) attribute value.
  • 32-bit Dose Values
  • Byte-order and word-order issues

13
Maintaining Consistent Object Linkage
  • DICOM RT objects reference each other.
  • Structure Set references images (Frame of
    Reference)
  • Plan references Structure Set
  • References are important for automated import.
  • Submission software should check that references
    are correct and complete.

14
Clinical Trials Identification
  • Data for a clinical patient must be de-identified
    and associated with a clinical trial subject.
  • DICOM Supplement 70 (Jan. 2003) introduces
    Clinical Trials ID modules which include 10 new
    attributes that can be added to any DICOM object
    to identify
  • Clinical trial sponsor
  • Clinical trial protocol
  • Clinical trial subject

15
Submission of DICOM Data to the ATC
  • Part-10 Filesets (currently supported)
  • CD-R media
  • FTP to ITC server (like RTOG Data Exchange)
  • ATC Submission System (in development)
  • Push DICOM data to WebSys client program (DICOM
    Storage SCP) on local PC
  • Replace patient ID with clinical trials ID
  • Perform secure upload to ATC server

16
Credentialing for Participation in Advanced
Technology Clinical Trials
  • Institutions must pass a dry run (benchmark)
    test by submitting a protocol-compliant data set
    to the ATC.
  • Treatment planning systems are said to be ATC
    compliant when a complete data set received from
    a real, clinical user is judged to be
    protocol-compliant.

17
Institutions Credentialed for RTOG Protocols
using DICOM RT
Protocol Institutions Credentialed
P-0232 Prostate brachytherapy 5
H-0022 Head-neck IMRT 1
P-0126 Prostate 3DCRT 1
as of 9/16/2003
18
ATC Efforts to Support DICOM Implementation for
Clinical Trials
  • DICOM Implementers Technical Workshops
  • March 16-17, 2001
  • March 16, 2002
  • May 3, 2003
  • Spring 2004
  • Assistance in evaluating compliance of data sets
  • Feedback to implementers via the web-based Remote
    Review Tool

19
Remote Review Tool
  • CT Images (zoom, window/level)
  • Structure contours (review, editing)
  • Iso-dose contours
  • Interactive DVH
  • Point-dose display

20
Conclusions
  • Advanced-technology clinical trials are
    attempting to correlate volumetric dosimetry
    information with clinical outcomes.
  • Expected to yield improved dose-response models.
  • Requires volumetric digital data
  • The DICOM RT objects are becoming a viable option
    for submission of data in these studies.
  • ATC compliant treatment planning systems are
    listed on the ITC website http//itc.wustl.edu .
    (ATC website coming in Fall, 2003.)
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