DICOM: Definitions and Testing
Using DICOM for Advanced
Technology Clinical Trials
Walter R. Bosch, D.Sc.
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”
Bosch – AAPM 2004
2
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
Bosch – AAPM 2004
3
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
Bosch – AAPM 2004
4
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
Bosch – AAPM 2004
online at the ATC web site: http://atc.wustl.edu
5
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 ).
Bosch – AAPM 2004
6
ATC Requirements: DICOM RT Dose
• Dose distributions are to be represented as a single, multi•
•
•
•
Bosch – AAPM 2004
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.)
7
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
Bosch – AAPM 2004
8
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
Bosch – AAPM 2004
9
ATC Compliant Treatment Planning Systems
• ATC compliant
treatment planning
systems are listed
on the ATC website
http://atc.wustl.edu.
• Represents
• Complete, protocolcompliant
submissions
• Clinical users
• Released software
Bosch – AAPM 2004
8/8/03
8/11/03
10/18/03
3/15/04
10
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)
*
Bosch – AAPM 2004
as of July 2004
11
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 Prostate
b. ATC04HN02 – IMRT Head/Neck
2. Instructions given at ATC DICOM Workshop and via email
a.
b.
c.
d.
Import images, structures
Create plans
Export CT images, RT Structure Set; RT Plan, RT Dose, RT Image
Submit to ITC by June 25, 2004
3. Display and compare submitted data at AAPM
•
•
Bosch – AAPM 2004
ATC web-based review tools
Compare submitted data to vendors’ conformance statements
12
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 – ATC04PR02
2. 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.
Bosch – AAPM 2004
13
Case 1 (ATC04PR02) –3DCRT Prostate
• Based on RTOG 0126
• 97 CT slices
• 10 Structures:
•
•
•
•
•
•
•
•
•
•
Bosch – AAPM 2004
PTV2 (high-dose)
PTV1 (low-dose)
Prostate/SV [CTV1]
CTV2
Bladder
Rectum
RT Femur
Lt Femur
Penile bulb
Skin
14
Case 1 (ATC04PR02) 3DCRT Treatment Plan Summary
• Prescription (ICRU Ref Dose)
PTV1: 57.97 Gy
PTV2: 82.28 Gy (44 fractions)
• 2 fraction groups (sub-plans)
with 6 beams each:
• RPO, Rlat, RAO, LAO, Llat, LPO
Maximum Dose to Percent of Volume
Bosch – AAPM 2004
15%
25%
35%
50%
Bladder
80 Gy
75 Gy
70 Gy
65 Gy
Rectum
75 Gy
70 Gy
65 Gy
60 Gy
15
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.
Bosch – AAPM 2004
16
ATC Review Tools
Remote Review Tool (RRT)
Image-guided Therapy QA Center
Computational Environment for
Radiotherapy Research (CERR)
James Alaly, Emiliano Spezi,
Joseph Deasy
Bosch – AAPM 2004
17
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 Image
b. 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, or
c. Media exchange.
Bosch – AAPM 2004
18
Summary
• In the past 12 months, DICOM has become a viable format
•
•
•
•
Bosch – AAPM 2004
for the submission of treatment planning data in advancedtechnology 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.
19