Object Positioning Apparatus Using DRR Matching

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Solution Overview

Problem

In radiotherapy, the inclusion of unnecessary pixel regions such as the bed and medical restraints in X-ray images hinders accurate patient positioning due to obstacles in matching processing between radiographic and reference images.

Innovation Solution

An object positioning apparatus and method that removes unnecessary pixel regions from X-ray images before matching with Digitally Reconstructed Radiograph (DRR) images, using image processing techniques to enhance matching accuracy by specifying and eliminating non-index regions like the bed and medical restraints, allowing only the bone region to serve as an index for precise positioning.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If pixel regions depicting unnecessary objects such as bed and medical restraint are removed from the DRR image, then the DRR image quality is improved, but the X-ray image still includes these unnecessary pixel regions which become obstacles to positioning

Engineering Contradiction:
ImproveDRR image qualityVSAvoidPositioning difficulty
Core Design Contradiction:
Measurement precisionVSEase of operation

Solution Approach 1:

The patent extracts and removes pixel regions depicting unnecessary objects (bed, medical restraint) from the X-ray image before performing matching processing with the DRR image. This extraction process isolates the useful information (patient anatomy) from harmful distractions, enabling accurate positioning by comparing only relevant anatomical structures between the two images.

Inventive Principle:
Principle #2Taking out (Extraction)

2Device complexity

If matching processing is performed between DRR image and X-ray image that both include unnecessary pixel regions, then processing is simpler, but matching accuracy deteriorates due to obstacles from unnecessary regions

Engineering Contradiction:
ImproveProcessing simplicityVSAvoidMatching accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent performs preliminary processing on the X-ray image by removing unnecessary pixel regions before the matching processing step. This preliminary action prepares the data in advance, ensuring that only relevant anatomical structures are present for comparison, thereby guaranteeing high matching accuracy without adding complexity to the subsequent processing steps.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3669785B1Object positioning apparatus, object positioning method, object positioning program, and radiation therapy system
Publication Date: 2021.10.13 TOSHIBA ENERGY SYST & SOLUTIONS CORP
  • EP3669785B1 patent drawingFigure 1
  • EP3669785B1 patent drawingFigure 2
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AI summary

An object positioning apparatus comprising: a radiographic image input interface configured to acquire a radiographic image that is generated by causing a fluoroscopic imaging apparatus to image an object and includes a first region and a second region, the first region depicting an index region for positioning of the object, the second region depicting a non-index region other than the index region; and a positioning processor configured to perform the positioning of the object by performing matching processing between a previously generated reference image and the first region that is specified from the radiographic image based on three-dimensional model information of the non-index region.