Multimodality Image Registration for Radiation Oncology 2013

Multimodality Image Registration for Radiation Oncology 2013 (MMRO-III) registers image sets specifically for Radiation Oncology.

Summary

Transmitting image registration information within the Radiation Oncology domain is important to the process of external beam radiation treatments. Currently, registration can be performed on individual workstations designed for that purpose and planning systems, but the results are not readily transferable between systems, often due either to proprietary or inconsistent implementations. This profile addresses the ability to convey registered data from one system to another for further processing. This profile addresses issues dealing with multiple coordinate systems but does not specifically address the issue of repeatable fused displays. A collection of DICOM objects exists to address the problem. Their use is constrained and clarified to avoid misinterpretation and promote compatibility.

Many newer treatment planning systems allow modalities other than CT to act as the primary image dataset and primary Frame-of-Reference definition. This profile extends MMRO and MMRO-II by allowing other modalities to define the primary FoR.

Benefits

• Defines how DICOM objects for spatial registration and the images themselves are created, stored, queried, retrieved, processed and displayed
• Allows multiple systems to use a single Spatial Registration Object, improving consistency between systems for region-of-interest and radiation dose display
• Verifies the consistency and correctness of patient orientation displays
• Improves safety by specifying images within a Frame of Reference that are associated with the Frame of Reference Definition
• Allows any supported image modality (CT, MR, PET) to define the primary Frame-of-Reference

Details

This Profile specifies how images, RT Structure Sets, RT Doses, and associated spatial registration information can be exchanged, stored, processed and displayed. For a display workstation, it is essential that a workstation correctly identifies the corresponding image sets, matches data from single-slice and multi-slice datasets, matches coordinate systems, and performs spatial translations. The use of relevant DICOM objects (Spatial Registration) is clarified and constrained in order to avoid misinterpretation.

The MMRO-III Profile focuses on content for image registration and does not define a registration workflow. Such workflow could be managed by using mechanisms described in a Post-Processing Workflow Integration Profile. The MMRO-III Profile currently only handles rigid registration. The intention is to add deformable registration as an extension to the Profile in the future.

The MMRO-III Profile does not specify the use of quantification methods for the image data that is created or displayed. In particular interoperability for PET Standard Uptake Values (SUV) is considered a relevant future work item for IHE. Note that vendors may wish to provide SUV capability even though not required under this Profile.

NOTE: This profile supersedes the MMRO and MMRO-II profiles. It corrects MMRO for changes made in the DICOM Spatial Registration Object in 2010. In addition, it requires that images known to be consistent with a Frame-of-Reference in an SRO be listed. This allows a user to know that the SRO referenced can be trusted with these specific images. It allows MR or PET to define the primary Frame-of-Reference, removing the limitation of only CT as the primary FoR in MMRO and MMRO-II.

Systems Affected

• Radiation Oncology PACS
• Treatment Planning Systems
• CT Simulation Systems

Actors and Transactions:

Specification

Profile Status: Final Text (currently in editing to add to the Technical Framework)

Underlying Standards:

• DICOM

See Also

Related Profiles

• [Basic_Radiation_Therapy_Objects-II Basic Radiation Therapy Objects-II] (BRTO-II) Provides base requirements for Structure Set and RT Plan Objects.

Consumer and Implementer Information

• IHE-RO Profiles including the MMRO-III profile.