DICOM Anniversary Conference Experience Using DICOM-RT Objects for

DICOM Anniversary Conference Experience Using DICOM-RT Objects 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.

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. Fitz. Gerald, M. Urie, K. Ulin • Support • NIH U 24 grant CA 81647, “Advanced Technology QA Center” Bosch – DICOM Anniversary Conf. 2003 2

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 3 DCRT and IMRT • Mission • Develop appropriate and uniform QA procedures and criteria • Facilitate sharing of developmental and QA resources for digital data submission and review Bosch – DICOM Anniversary Conf. 2003 3

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. Bosch – DICOM Anniversary Conf. 2003 4

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 Bosch – DICOM Anniversary Conf. 2003 5

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. Bosch – DICOM Anniversary Conf. 2003 6

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 Open 8/15 0 0 BR-0319 Breast Ph I/II * as of 9/16/2003 Bosch – DICOM Anniversary Conf. 2003 7

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 Bosch – DICOM Anniversary Conf. 2003 8

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 Bosch – DICOM Anniversary Conf. 2003 9

DICOM RT Objects Needed for Advanced Technology Clinical Trials • A participant must submit a complete, protocolcompliant 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: IMPORT CT Image MR Image RT Structure Set RT Plan EXPORT Treatment Planning System RT Plan RT Image • Only recently have commercial treatment planning systems begun to export this complete set of objects. Bosch – DICOM Anniversary Conf. 2003 10

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 (300 A, 000 C) 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. Bosch – DICOM Anniversary Conf. 2003 11

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 Bosch – DICOM Anniversary Conf. 2003 12

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. Bosch – DICOM Anniversary Conf. 2003 13

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 Bosch – DICOM Anniversary Conf. 2003 14

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 Web. Sys client program (DICOM Storage SCP) on local PC • Replace patient ID with clinical trials ID • Perform secure upload to ATC server Bosch – DICOM Anniversary Conf. 2003 15

Credentialing for Participation in Advanced Technology Clinical Trials • Institutions must pass a “dry run” (benchmark) test by submitting a protocolcompliant 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. Bosch – DICOM Anniversary Conf. 2003 16

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 3 DCRT 1 * as of 9/16/2003 Bosch – DICOM Anniversary Conf. 2003 17

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 Bosch – DICOM Anniversary Conf. 2003 18

Remote Review Tool • CT Images (zoom, • • window/level) Structure contours (review, editing) Iso-dose contours Interactive DVH Point-dose display Bosch – DICOM Anniversary Conf. 2003 19

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. ) Bosch – DICOM Anniversary Conf. 2003 20