Monte Carlo Scatter Estimation via Simulation Subset Selection

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Solution Overview

Problem

Conventional Monte Carlo simulation methods for scatter estimation in X-ray imaging are inefficient, particularly for 3D volume images, requiring significant calculation time and resources, and often yield less than satisfactory results due to inadequate sampling and interpolation methods, especially with complex anatomy.

Innovation Solution

The method involves selecting a simulation subset of 2D projection images based on relative signal change and forming a simulation region to reduce the number of photons directed to high-exposure regions, adjusting photon weighting, and using angular dependent photon distribution to improve scatter characterization and correction, thereby streamlining the Monte Carlo simulation process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional Monte Carlo simulation methods are used for scatter estimation in 3D volume images, then comprehensive scatter characterization can be achieved, but calculation time and computational resources increase substantially

Engineering Contradiction:
Improvescatter estimation accuracyVSAvoidcalculation time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent divides the complete set of projection images into a simulation subset and a correction set. The simulation subset is used for Monte Carlo scatter estimation, while the correction set undergoes scatter correction using the estimated scatter parameters. This segmentation reduces the computational burden by limiting the Monte Carlo simulation to only a portion of the data while maintaining comprehensive scatter characterization across all images.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies Monte Carlo simulation to only a partial subset of projection images rather than processing all images through full Monte Carlo simulation. By selecting representative images from the simulation subset that capture the range of scatter conditions, the method achieves adequate scatter characterization with reduced calculation time and resources compared to processing the complete dataset.

Inventive Principle:
Principle #16Partial or excessive action

2Reliability

If Monte Carlo simulation is applied to all acquired projection images, then complete scatter correction can be achieved, but computational resources and calculation time become prohibitively large

Engineering Contradiction:
Improvescatter correction completenessVSAvoidprocessing efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent segments the projection images into two distinct groups: a simulation subset used for Monte Carlo scatter estimation and a correction set used for applying scatter correction. This division allows the computationally intensive Monte Carlo simulation to be performed on fewer images while still enabling comprehensive scatter correction across all acquired projection images, thereby improving processing efficiency without sacrificing correction completeness.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent creates scatter estimates from the simulation subset that represent the scatter characteristics of the entire dataset. These scatter estimates are then applied as corrections to all projection images in the correction set, effectively copying the scatter correction parameters from the simulated subset to the full dataset, which maintains correction reliability while dramatically improving productivity.

Inventive Principle:
Principle #26Copying

3Measurement precision

If standard Monte Carlo methods are used without optimization, then thorough scatter modeling can be performed, but the method requires considerable calculation time and resources

Engineering Contradiction:
Improvescatter modeling accuracyVSAvoidcomputational resources
Core Design Contradiction:
Measurement precisionVSUse of energy by stationary object

Solution Approach 1:

The patent segments the computational workload by applying Monte Carlo simulation only to a simulation subset of projection images rather than processing all images. This segmentation maintains thorough scatter modeling accuracy for the represented conditions while reducing computational resource consumption by limiting the scope of the intensive Monte Carlo calculations to a manageable subset of the total data.

Inventive Principle:
Principle #1Segmentation

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach significantly reduces calculation time and resources, enhances scatter estimation accuracy, and improves image quality by efficiently characterizing and correcting scatter effects in 3D X-ray images, especially for complex anatomy like extremities, without compromising accuracy.

Implementation Method 1

The primary X-ray beam is directed towards and bombards the sample with some of the X-ray radiation being absorbed, a smaller amount being scattered

Methodology Applied
Scientific EffectX-ray radiation: X-Ray

Implementation Method 2

Scatter occurs when radiation from the x-ray source reaches a detector by an indirect path

Methodology Applied
Scientific EffectCompton scattering: Compton Scattering

Data Source

PatentUS10813616B2Variance reduction for monte carlo-based scatter estimation
Publication Date: 2020.10.27 CARESTREAM HEALTH INC
  • US10813616B2 patent drawing
  • US10813616B2 patent drawing
  • US10813616B2 patent drawing

AI summary

A method rotates a radiation source and a detector over a sequence of acquisition angles about a subject and acquires, at each acquisition angle, a 2D projection image. A simulation subset is formed that contains some, but not all, of the acquired 2D projection images, wherein subset membership is determined according to relative signal change between successive 2D projection images. Scatter is characterized for the acquired sequence of projection images according to the formed simulation subset. One or more of the acquired sequence of projection images is corrected using the scatter characterization. An image volume is reconstructed and stored according to the sequence of scatter corrected projection images. One or more images of the reconstructed image volume are rendered to a display or transmitting the stored image volume data.