Analytical Reconstruction for Multi-Tracer TOF-PET Imaging

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Solution Overview

Problem

Current TOF-PET imaging methods are inefficient in reconstructing the position and time of ortho-positronium annihilation into three gamma quanta, requiring a large number of computation operations and often necessitating prior discretization of the image, which limits spatial and temporal resolution and prolongs diagnostic time, especially when imaging with multiple tracers.

Innovation Solution

A fast analytical reconstruction method that determines the position and time of ortho-positronium annihilation into three gamma quanta without image discretization, using a block diagram process involving TOF-PET detectors to record and process gamma quantum interactions, and an algorithm flow diagram that geometrically determines the common decay plane and solves for the decay point with a closed-form analytical solution, reducing computational load and improving resolution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional iterative reconstruction methods are used for ortho-positronium annihilation events, then reconstruction accuracy can be achieved, but computational time and complexity increase significantly

Engineering Contradiction:
Improvereconstruction accuracyVSAvoidcomputational time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent replaces iterative computational mechanics with a closed-form analytical solution. By deriving direct mathematical formulas that calculate the decay point position and time from gamma quantum interaction data, the system eliminates the need for repeated iterative computations while maintaining reconstruction accuracy, thereby dramatically reducing computational time

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the mathematical approach from iterative parameter optimization to direct parameter calculation using closed-form equations. The analytical solution directly computes spatial and temporal parameters of ortho-positronium annihilation events without requiring successive approximation, transforming the computational paradigm to achieve both accuracy and efficiency

Inventive Principle:
Principle #35Parameter changes

2Device complexity

If image discretization is applied in reconstruction, then computational complexity is reduced, but spatial and temporal resolution deteriorate

Engineering Contradiction:
Improvecomputational complexityVSAvoidspatial and temporal resolution
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent substitutes the discretization-based computational approach with a continuous analytical solution. The closed-form equations operate on continuous spatial and temporal domains, preserving full resolution information while maintaining computational tractability through mathematical elegance rather than spatial binning

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent transitions from discrete voxel-based reconstruction to continuous spatial reconstruction by introducing analytical dimensionality. The closed-form solution operates in continuous coordinate space, effectively adding a dimension of precision beyond the discrete grid limitations of conventional methods

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Adaptability or versatility

If multiple tracers are imaged simultaneously using conventional methods, then diagnostic information increases, but reconstruction time and computational load increase significantly

Engineering Contradiction:
Improvemulti-tracer imaging capabilityVSAvoiddiagnostic throughput
Core Design Contradiction:
Adaptability or versatilityVSProductivity

Solution Approach 1:

The patent segments the multi-tracer reconstruction problem into independent analytical calculations for each tracer. By applying the closed-form solution to each tracer's event data separately and combining results, the system achieves multi-tracer capability without the exponential computational burden that would result from treating all tracers as a single integrated reconstruction problem

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent performs preliminary analytical reconstruction for each tracer independently using closed-form equations before combining the results. This preliminary segmentation of the reconstruction task allows parallel processing of multiple tracers, significantly improving diagnostic throughput while maintaining accuracy

Inventive Principle:
Principle #10Preliminary action

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 method significantly reduces computational requirements, enhances spatial and temporal resolution, and enables simultaneous multi-tracer PET imaging with unlimited distinct tracers, speeding up the diagnostic process and improving image quality.

Implementation Method 1

Events corresponding to the registration of two 511 keV gamma quanta are identified based on the energy deposited in scintillators via photoelectric or Compton effects

Methodology Applied
Scientific EffectPhotoelectric effect: Photoelectric Effect

Implementation Method 2

Events corresponding to the registration of two 511 keV gamma quanta are identified based on the energy deposited in scintillators via photoelectric or Compton effects

Methodology Applied
Scientific EffectCompton scattering: Compton Scattering

Implementation Method 3

TOF-PET detectors equipped with dedicated electronics and software enable a reconstruction of positions and times of gamma quanta interaction in scintillator material

Methodology Applied
Scientific EffectScintillation: Scintillation

Implementation Method 4

Current TOF-PET scanners additionally utilize information about time difference between the time-of-flights (TOF) of gamma quanta from the annihilation point to the detectors

Methodology Applied
Scientific EffectTime of flight: Time of Flight

Data Source

PatentEP3347742B1Method for reconstructing multi-tracer metabolic and morphometric images and tomography system for multi-tracer metabolic and morphometric imaging
Publication Date: 2020.02.12 JAGIELLONIAN UNIVERSITY
  • EP3347742B1 patent drawingFigure 1
  • EP3347742B1 patent drawingFigure 2
  • EP3347742B1 patent drawingFigure 3

AI summary

The subject of the invention concerns a method for reconstructing multi-tracer metabolic and morphometric images by determining time and three-dimensional spatial coordinates of position of positron-electron annihilation into three gamma quanta, the method comprising the steps of: receiving a plurality of events from positron annihilation centers obtained during measurements conducting by TOF-PET tomography, reconstructing time and spatial coordinates for plurality of events collected in first step, determination of a common plane for gamma quanta originating from positron-electron annihilation, transforming a time and spatial coordinates for gamma quanta to a decay plane determined in the previous step, determining in defined in third step decay plane a time and spatial coordinates for an annihilation place, transforming time and spatial coordinates for an reconstructed annihilation place from decay plane reference frame to the image reference frame. The invention also pertains to the tomography system for multi-tracer metabolic and morphometric imaging of an interior of an examined object.