Pre-computed DRR Knowledge Base for Real-time Image Registration

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Solution Overview

Problem

Conventional methods for registering pre-operative and intra-operative images are computationally intensive, taking several minutes to complete, which is not suitable for real-time applications in minimally invasive therapeutic interventions, and compromise on robustness when reducing computation time.

Innovation Solution

Pre-computing Digitally Reconstructed Radiographs (DRRs) for various poses and storing them in a knowledge base, allowing for efficient retrieval and registration of pre-operative and intra-operative images in real-time by matching signatures from both sets.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If conventional registration methods are used to register pre-operative and intra-operative images, then registration accuracy is maintained, but registration time becomes too long (several minutes) for real-time applications

Engineering Contradiction:
Improveregistration speedVSAvoidregistration time
Core Design Contradiction:
SpeedVSLoss of time

Solution Approach 1:

The patent pre-computes and stores a knowledge base of DRRs (Digitally Reconstructed Radiographs) for various poses before the actual registration process. This preliminary computation allows the system to quickly retrieve and match images during real-time procedures, reducing registration time from several minutes to near real-time speeds while maintaining accuracy.

Inventive Principle:
Principle #10Preliminary action

2Speed

If computation time is reduced by randomly sampling DRRs, then registration speed improves, but robustness of results is compromised due to less information available to the optimizer

Engineering Contradiction:
Improveregistration speedVSAvoidregistration robustness
Core Design Contradiction:
SpeedVSReliability

Solution Approach 1:

Instead of randomly sampling during the actual registration process, the system pre-computes and stores a comprehensive knowledge base of DRRs for various poses. This allows the system to retrieve relevant pre-computed images for matching, maintaining both speed and robustness by having full information available without requiring time-consuming optimization iterations.

Inventive Principle:
Principle #10Preliminary action

3Measurement precision

If three dimensional images are used to provide high resolution anatomical detail, then image quality improves, but acquisition time and intrusiveness to the physician increase significantly

Engineering Contradiction:
Improveanatomical detail resolutionVSAvoidimage acquisition time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent separates the imaging modalities into two segments: pre-operative 3D imaging (CT or MRI) for acquiring high-resolution anatomical details, and intra-operative 2D imaging (X-ray or fluoroscopy) for real-time procedural guidance. This segmentation allows each modality to serve its optimal purpose - detailed anatomy from 3D pre-op images and quick, less intrusive 2D images during the procedure.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system performs the time-consuming 3D image acquisition and DRR generation before the actual surgical procedure. By pre-computing the knowledge base of DRRs from pre-operative 3D images, the system eliminates the need to acquire 3D images in real-time during the procedure, maintaining high resolution while reducing intra-operative time and intrusiveness.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentUS7620223B2Method and system for registering pre-procedural images with intra-procedural images using a pre-computed knowledge base
Publication Date: 2009.11.17 SIEMENS MEDICAL SOLUTIONS USA INC
  • US7620223B2 patent drawing
  • US7620223B2 patent drawing
  • US7620223B2 patent drawing

AI summary

A system and method for registering pre-operative images of an object with an intra-operative image of the object is disclosed. Prior to an operative procedure, Digitally Reconstructed Radiographs (DRRs) are generated for the pre-operative images of each individual patient. Signatures are extracted from the DRRs. The signatures are stored in a knowledge base. During the operative procedure, a signature is extracted from the intra-operative image. The intra-operative signature is compared to the stored pre-operative signatures. A pre-operative image having a best signature match to the intra-operative signature is retrieved. The retrieved pre-operative image is registered with the intra-operative image.