Partial-Ring PET Reconstruction Using TOF and Reduced Angle System Matrix

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Solution Overview

Problem

Partial-ring positron emission tomography (PET) systems face challenges with incomplete angular view sampling, leading to artifacts in image reconstruction, particularly in limited angle applications such as breast imaging and radiation therapy, where full-ring detectors are not feasible due to geometric constraints.

Innovation Solution

A method for reconstructing images from limited angle PET data using a reduced angle system matrix and iterative optimization, incorporating time-of-flight (TOF) information to maximize data quality and accounting for the partial geometry of partial-ring detectors, which includes selecting a reduced angle system matrix and using anatomical priors for improved reconstruction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If partial-ring detectors are used to allow closer positioning to patient anatomy and improve sensitivity, then sensitivity is improved, but incomplete angular view sampling occurs causing artifacts in image reconstruction

Engineering Contradiction:

ImprovesensitivityVSAvoidimage reconstruction quality

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent applies TOF PET techniques which change the temporal resolution parameter of the detection system. By measuring the time of flight of annihilation photons, the system can compensate for the limited angular coverage of partial-ring detectors, reducing artifacts while maintaining the sensitivity benefits of closer detector positioning to patient anatomy

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces an intermediate reconstruction technique that uses TOF information as a mediator between the limited angular data and the final image reconstruction. This intermediary approach allows the system to achieve artifact-free images by incorporating temporal information that compensates for the incomplete angular sampling

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If full-ring detectors are used to achieve complete angular view sampling, then image reconstruction quality is improved, but detectors cannot be positioned closer to patient anatomy reducing sensitivity

Engineering Contradiction:

Improveimage reconstruction qualityVSAvoidsensitivity

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent changes the detection parameter from spatial coverage (full-ring geometry) to temporal resolution (TOF measurement). This parameter change allows partial-ring detectors to achieve image reconstruction quality comparable to full-ring systems by using time-of-flight information to compensate for the reduced angular coverage

Inventive Principle:

Principle #35Parameter changes

3Device complexity

If conventional image reconstruction techniques are used with limited angle PET data, then computational simplicity is maintained, but artifacts appear in reconstructed images

Engineering Contradiction:

Improvereconstruction complexityVSAvoidimage reconstruction quality

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent modifies the reconstruction approach by incorporating TOF parameters into the reconstruction algorithm. This parameter enhancement allows conventional reconstruction techniques to be improved with minimal additional complexity while eliminating artifacts caused by limited angle sampling

Inventive Principle:

Principle #35Parameter changes

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 enables artifact-free image reconstruction with improved sensitivity and field-of-view, allowing for accurate verification of ion beam therapy delivery and minimizing biological washout and patient repositioning errors by leveraging TOF PET techniques.

Implementation Method 1

PET imaging can be used for the verification of hadron therapies

Methodology Applied

Scientific EffectRadioactive decay: Radioactive Decay

Implementation Method 2

these radionuclide species have half-lives on the order of only a few minutes (e.g., 2-20 minutes)

Methodology Applied

Scientific EffectAnnihilation radiation: Radiation

Implementation Method 3

Time-of-flight ('TOF') PET can be used to improve the image quality achievable with partial-ring PET systems because the number of angular views necessary for an artifact-free image reconstruction can be decreased based on the increased temporal resolution achievable with TOF PET techniques

Methodology Applied

Scientific EffectTime of flight: Time of Flight

Data Source

PatentUS9870627B2System and method for limited angle positron emission tomography

Publication Date: 2018.01.16 THE GENERAL HOSPITAL CORP

AI summary

Described here are systems and methods for reconstructing images from limited angle positron emission tomography (“PET”) data acquired using a PET system with a partial-ring detector configuration, such as an in-beam PET system. The reconstruction process is specifically designed to account for the limited angular coverage of the partial-ring detector by implementing a reduced angle system matrix in an iterative reconstruction process.