using dicom for advanced technology clinical trialsusing dicom for advanced technology clinical...

DICOM: Definitions and Testing

Using DICOM for Advanced Technology Clinical Trials

Walter R. Bosch, D.Sc.

Bosch – AAPM 2004 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”


Advanced Technology Clinical Trials• Collect digital treatment planning

data to link with clinical outcomes • Evaluate response statistics• Develop dose-response models

• Treatment planning based on volumetric model of patient anatomy and 3-D dose distributions

• Maintain temporal pattern of dose delivery


Data for Advanced-Technology Clinical Trials in Radiotherapy

• Primary data (patient model, dosimetry)• Patient Volumetric Image – CT Image• Structures: GTV, CTV, PTV, OAR – RT

Structure Set• 3-D Dose Distribution (including

fractionation information) – RT Dose

• Secondary data (QA of primary data)• Treatment Plan Specification – RT Plan• Dose-Volume Histograms – RT Dose• Digital Simulator and Portal Images – RT

Image


Special Requirements for Attributes• The ATC DICOM File Set Reader Conformance

Statement* is a detailed list of the attributes required for each DICOM object• Attributes whose values must be specified for clinical trials

submissions (including DICOM Type 2 or 3 attributes)• Special requirements for attributes values

• Reference Guide to the ATC DICOM File Set Reader Conformance Statement* summarizes the conformance statement and highlights special requirements.

*Available online at the ATC web site: http://atc.wustl.edu


ATC Requirements: DICOM RT Structure Set

• Structure contours must be planar and defined in transverse planes whose axial positions coincide with those of images.

• For external beam protocols, an external patient contour (“skin”) is required on all axial positions.

• Structures must reflect the extent of volumes contoured by the physician, e.g., target volumes must not interfere with overlapping, contoured structures.

• Structures are to be submitted with protocol-defined structure names (see http://atc.wustl.edu ).


ATC Requirements: DICOM RT Dose• Dose distributions are to be represented as a single, multi-

frame object (rather than multiple, planar doses).• A separate dose array is required for each fraction group

(set of beams or brachytherapy sources which are delivered together, in constant proportion).

• Doses must be specified as absolute, physical dose (in Gy).• Dose array must represent all meaningful dose (outside the

array, dose is assumed to be zero).• A DVH is to be submitted for total dose plan only. (DVHs

may be submitted graphically.)


ATC Requirements: DICOM RT Plan• RT Plan Geometry (300A,000C) must be PATIENT• External Beam 3DCRT – beam energy, aperture, beam

modifiers are used for setup and beam weight QA.• External Beam IMRT – beam information is not currently

used for QA.• Permanent Implant Brachytherapy

• Seed model and strength at implant• Seed locations in patient space

• HDR Brachytherapy• Source geometry and dwell positions in patient space• Source strength• Dwell times


ATC Requirements: DICOM RT Image

• Requirements are protocol-specific• RT Image objects can be used for

• DRRs• Digitized simulator images/films• Digitized port images/films

• RT Image is preferred to Secondary Capture or Computed Radiography when relationship to beam is known


ATC Compliant Treatment Planning Systems

• ATC compliant treatment planning systems are listed on the ATC website http://atc.wustl.edu.

• Represents• Complete, protocol-

compliant submissions

• Clinical users • Released software

8/8/038/11/03

10/18/03

3/15/04


Progress over the past 12 months*

• Four treatment planning systems have ATC compliant DICOM export capabilities• Eight additional TPS are “works in progress”

• 40 institutions have been credentialed using DICOM submissions • Some for multiple protocols• Some with multiple TPS

• 194+ DICOM data submission to ITC• 123 “dry run” submissions• 50 protocol case data sets (RTOG protocols)• 21 phantom data sets (evaluated by RPC)

* as of July 2004


ATC/AAPM/DICOM WG7 Demonstration Phase 1: DICOM Export (2004)1. Two test data sets (DICOM CT Image Series and RT

Structure Set object, planning instructions) were distributed to TPS manufacturers through DICOM WG7:a. ATC04PR02 – 3DCRT Prostateb. ATC04HN02 – IMRT Head/Neck

2. Instructions given at ATC DICOM Workshop and via emaila. Import images, structuresb. Create plansc. Export CT images, RT Structure Set; RT Plan, RT Dose, RT Imaged. Submit to ITC by June 25, 2004

3. Display and compare submitted data at AAPM• ATC web-based review tools• Compare submitted data to vendors’ conformance statements


Phase 1 Test Data Sets• Two test data sets were created as a starting point for

treatment planning:1. 3DCRT Prostate, based on RTOG 0126 – ATC04PR022. IMRT Nasopharynx, based on RTOG 0225 – ATC04HN02

• Data were de-identified and attempts were made to facilitate import into treatment planning systems:• Private attributes were removed from DICOM objects.• Structure Sets contour Z positions coincided with those of CT

slices.• However, one of the data sets had irregularly spaced CT slices.

• John Matthews at ITC received, imported, and evaluated data sets and gave feedback to participants.


Case 1 (ATC04PR02) –3DCRT Prostate

• Based on RTOG 0126• 97 CT slices• 10 Structures:

• PTV2 (high-dose)• PTV1 (low-dose)• Prostate/SV [CTV1]• CTV2• Bladder• Rectum• RT Femur• Lt Femur• Penile bulb• Skin


Case 1 (ATC04PR02) 3DCRT Treatment Plan Summary

• Prescription (ICRU Ref Dose)PTV1: 57.97 GyPTV2: 82.28 Gy (44 fractions)

• 2 fraction groups (sub-plans) with 6 beams each:• RPO, Rlat, RAO, LAO, Llat, LPO

50%35%25%15%

60 Gy65 Gy70 Gy75 GyRectum

65 Gy70 Gy75 Gy80 GyBladder

Maximum Dose to Percent of Volume


DICOM Objects Submitted to ATC• Eight manufacturers submitted

DICOM data sets.• Data from nine TPS included

• CT Image• RT Structure Set• RT Plan• RT Dose (3D dose array).

• Partial data sets were submitted from three other systems.

• See ATC Booth #1634 for a display of data sets submitted by demonstration participants.


ATC Review Tools

Remote Review Tool (RRT)Image-guided Therapy QA Center

Computational Environment for Radiotherapy Research (CERR)James Alaly, Emiliano Spezi, Joseph Deasy


ATC/AAPM/DICOM WG7 Demonstration Phase 2: DICOM Import (2005)1. Use phase 1 data to create a library of

manufacturers’ DICOM objects for off-line testing:a. From each TPS: CT Image, RT Structure Set, RT Plan,

RT Dose, RT Imageb. ATC web-based review tools provide displays of what

data should look like.2. Demonstrate exchange using …

a. Manufacturer-to-manufacturer network exchange,b. Central Test Node, orc. Media exchange.


Summary• In the past 12 months, DICOM has become a viable format

for the submission of treatment planning data in advanced-technology clinical trials.

• The ATC DICOM Conformance Statement provides a uniform “profile” for use of RT objects in clinical trials.

• The Image-Guided Therapy QA Center (an ATC member) provides assistance to vendors in their development of DICOM export capabilities through data set evaluation and web-based review tools.

• The ATC/AAPM/DICOM WG7 Demonstration appears to have accelerated the process of vendor implementation of DICOM export capabilities for advanced-technology clinical trials.

• Data collected this year should prove valuable for a demonstration of import capabilities in 2005.

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