PET Imaging Positron Position Estimation Without Back Projection

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Solution Overview

Problem

Current nuclear medicine imaging apparatuses, such as PET scanners, require a long time to reconstruct and generate images using the back projection process, leading to delayed image production.

Innovation Solution

The implementation of a PET apparatus that estimates the spatial position of positrons based on detector positions and detection times, allocating pixel values to pixels corresponding to a gradation width determined by temporal resolution, allowing for real-time image generation without the need for back projection reconstruction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the back projection process is used for image reconstruction, then the PET image can be generated with high accuracy, but the image generation time becomes excessively long

Engineering Contradiction:

Improveimage reconstruction accuracyVSAvoidimage generation time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent extracts only the essential information needed for image reconstruction by directly using detection time data to determine spatial positions, eliminating the need for the complex back projection process. This extraction of key parameters (detection times and spatial positions) allows for rapid image generation without sacrificing essential reconstruction accuracy.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the fundamental parameter used for reconstruction from the traditional back projection method to a direct spatial position calculation method based on detection time differences. By changing the reconstruction parameter from iterative projection data to direct time-based position calculation, the system achieves both speed and accuracy.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If the back projection process is used for image reconstruction, then the PET image can be generated with high accuracy, but the operational efficiency decreases

Engineering Contradiction:

Improveimage reconstruction accuracyVSAvoidoperational efficiency

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The patent replaces the mechanical iterative back projection process with a direct calculation system that uses detection time data to immediately determine spatial positions. This substitution of the reconstruction mechanism eliminates the time-consuming iterative nature of back projection while maintaining the ability to generate accurate PET images, thereby significantly improving operational efficiency.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If real-time image display is implemented, then the operational efficiency improves, but the image quality may be compromised

Engineering Contradiction:

Improveoperational efficiencyVSAvoidimage quality

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent performs preliminary action by directly calculating spatial positions from detection time data during the acquisition phase itself, rather than requiring a separate reconstruction phase. This preliminary determination of spatial positions based on detection times enables real-time image display while maintaining quality, as the essential reconstruction information is obtained immediately during data collection.

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 approach significantly reduces the time required to generate PET images, enabling real-time image display during imaging operations and flexible post-processing of images based on designated conditions.

Implementation Method 1

The PET apparatus detects the gamma rays using detectors that are arrange in a ring shape around the subject

Methodology Applied

Scientific EffectGamma ray detection: Absorption (EM radiation)

Implementation Method 2

the PET apparatus having the TOF function calculates the spatial position of the positron on the LOR using the difference between the detection times when the set of detectors detect the gamma rays

Methodology Applied

Scientific EffectTime of flight (TOF): Time of Flight

Implementation Method 3

the positron emitting nuclides that are selectively introduced into the body tissues of the subject emit positrons and the emitted positrons are coupled to electrons and are then extinguished. In this case, the positron emits a pair of gamma rays substantially in the opposite direction

Methodology Applied

Scientific EffectPositron-electron annihilation: Nuclear Fission

Data Source

PatentUS9226716B2Nuclear medicine imaging apparatus and radiation therapy apparatus

Publication Date: 2016.01.05 TOSHIBA MEDICAL SYST CORP

AI summary

A nuclear medicine imaging apparatus according to an embodiment includes a gradation width storage, an estimating unit, and an image generating unit. The gradation width storage is configured to store the gradation width of an image determined by the temporal resolution of a detector. The estimating unit is configured to estimate the spatial position of a positron on the basis of the spatial position of a set of detectors and a set of detection times. The image generating unit is configured to allocate pixel value to pixels corresponding to the gradation width around the estimated spatial position such that a spatial resolution corresponding to the temporal resolution is reflected on a line linking the set of detectors, thereby generating an image.