Radiation Therapy Controller Selective CT Image Update

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Solution Overview

Problem

The Iterative Reconstruction method for generating CT images improves image quality but increases calculation time due to repeated processes of error reflection and image reconstruction to minimize pixel errors, which is inefficient for radiation therapy device controllers.

Innovation Solution

A radiation therapy device controller that selects CT image data based on body motion phases, generates radiation projection images at various angles, calculates luminance update amounts for each pixel, and updates CT image data only for pixels with significant luminance changes, allowing for efficient high-quality image generation and accurate diseased portion tracking.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the Iterative Reconstruction method is used to generate CT images, then image quality is improved, but calculation time increases due to repeated error reflection and image reconstruction processes

Engineering Contradiction:
Improveimage qualityVSAvoidcalculation time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent pre-calculates and stores correction data (projection images and correction values) for multiple respiratory phases before actual treatment. This preliminary preparation allows the system to quickly retrieve and apply pre-computed corrections during real-time treatment without performing full iterative reconstruction, thus maintaining high image quality while reducing calculation time.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent divides the CT image into multiple regions of interest (ROIs) based on anatomical structures and motion characteristics. By applying iterative reconstruction only to specific ROIs where high precision is needed rather than the entire image, the system maintains diagnostic quality in critical areas while significantly reducing overall calculation time.

Inventive Principle:
Principle #1Segmentation

2Measurement precision

If CT image quality is improved to accurately identify diseased portion position, then radiation targeting accuracy is improved, but processing time increases

Engineering Contradiction:
Improvediseased portion position accuracyVSAvoidprocessing time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent applies different processing strategies to different regions of the CT image based on their importance and motion characteristics. High-resolution iterative reconstruction is applied only to regions containing the diseased portion or critical anatomical structures, while other regions use faster reconstruction methods, thus maintaining positioning accuracy for radiation targeting while reducing overall processing time.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The system pre-identifies and marks regions of interest containing the diseased portion before treatment. These pre-identified ROIs are then used to guide the selective application of high-quality reconstruction algorithms only where needed for accurate disease localization, avoiding unnecessary processing of entire images and reducing overall processing time.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP2687258B1Control device for radiation therapy device, processing method and program for same
Publication Date: 2016.08.31 MITSUBISHI HEAVY IND LTD
  • EP2687258B1 patent drawingFigure 1
  • EP2687258B1 patent drawingFigure 2
  • EP2687258B1 patent drawingFigure 3

AI summary

A radiation therapy device controller identifiesa pixel on a straight line connecting a ray source and a sensor array, and calculates a luminance update amount candidate value for each identified pixel based on a ratio of a change amount for the pixel on the straight line indicating the living body to a sum of change amounts from a luminance value of a pixel corresponding to a correlated computed tomography image correlated with a computed tomography image of an update target of a luminance value of the identified pixel. Also, the control device calculates a luminance update amount of each identified pixel using the luminance update amount candidate value of each identified pixel calculated for a plurality of rotation angles, and updates the luminance value of each corresponding pixel of the computed tomography image of the update target using the luminance update amount of each identified pixel.