Compton Camera Pixel Electrode Arrangement for Electron Tracking

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Solution Overview

Problem

Compton cameras using semiconductor detectors face challenges in confining the incidence direction of electromagnetic radiation due to limitations in measuring the recoiling direction of recoil electrons, leading to low spatial resolution and high dead time, which hinders practical implementation.

Innovation Solution

A radiation measuring apparatus with semiconductor detectors is designed to specify the incidence direction of electromagnetic radiation by using the recoiling direction of recoil electrons, featuring pixel electrodes arranged closely to improve spatial resolution and reduce dead time, allowing for continuous data acquisition.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If pixel electrodes are arranged closely to improve spatial resolution, then measurement precision is improved, but device complexity increases

Engineering Contradiction:
Improvespatial resolutionVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The semiconductor detector is divided into multiple pixel electrodes arranged in a matrix pattern, with each pixel electrode independently detecting radiation interaction positions. This segmentation enables precise spatial resolution by identifying exactly where Compton scattering and photoelectric absorption occur within the detector, while the modular pixel structure manages complexity through systematic repetition of identical electrode units.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent transitions from one-dimensional detection to two-dimensional matrix arrangement of pixel electrodes, enabling spatial resolution in both horizontal and vertical directions. This dimensional expansion allows the system to precisely locate interaction positions on the detector surface, improving spatial resolution while the regular grid pattern provides a manageable structural framework.

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

2Measurement precision

If the apparatus uses recoil electron tracking to confine incidence direction, then measurement precision is improved, but productivity decreases due to high dead time

Engineering Contradiction:
Improveincidence direction specification accuracyVSAvoiddata acquisition rate
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The patent applies partial action by selectively tracking only the necessary components of electron recoil direction that contribute to incidence direction specification. Rather than attempting to measure all aspects of electron behavior, the system focuses on the projection of electron movement between interaction points, which is sufficient for determining radiation incidence direction while reducing processing complexity and dead time.

Inventive Principle:
Principle #16Partial or excessive action

Solution Approach 2:

The patent replaces complex mechanical electron tracking systems with a semiconductor-based detection approach. Instead of using physical electron trackers or gas chambers, the system uses semiconductor detectors to measure interaction positions and calculates electron recoil direction from the spatial relationship between Compton scattering and photoelectric absorption events, significantly reducing dead time and improving data acquisition rate.

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

3Manufacturing precision

If the apparatus uses semiconductor detectors with closely arranged pixel electrodes, then manufacturing precision requirements increase, but ease of manufacture decreases

Engineering Contradiction:
Improvepixel electrode arrangement precisionVSAvoidease of manufacture
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The detector is segmented into standardized pixel electrodes that can be manufactured using conventional semiconductor fabrication processes. Each pixel electrode is an identical, reproducible unit with defined dimensions and spacing, allowing mass production through standard photolithography and etching techniques, thereby managing manufacturing precision requirements through process standardization.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent specifies optimal parameter ranges for pixel electrode dimensions and spacing (e.g., 10-100 micrometers) that balance manufacturing feasibility with detection performance. By defining specific parameter ranges rather than requiring extreme precision, the design accommodates conventional manufacturing capabilities while achieving sufficient spatial resolution for practical applications.

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

The apparatus achieves improved spatial resolution and reduced dead time, enabling the practical realization of an electron tracking-type Compton camera that effectively confines the incidence direction of electromagnetic radiation, enhancing the accuracy of radiation source distribution imaging.

Implementation Method 1

a photon of the incident gamma ray collides with an electron in the substance to be scattered. At this time, the electron with which the photon has collided spatters (the spattered electron is called 'a recoil electron') and a part of energy of the photon of the incident gamma ray is given to the electron.

Methodology Applied
Scientific EffectCompton scattering: Compton Scattering

Implementation Method 2

the photon to have been scattered in the Compton scattering is absorbed by the absorber in the photoelectric absorption

Methodology Applied
Scientific EffectPhotoelectric absorption: Photoelectric Effect

Data Source

PatentEP3316003B1Radiation measuring apparatus
Publication Date: 2020.07.08 MITSUBISHI HEAVY IND LTD
  • EP3316003B1 patent drawingFigure 1~2
  • EP3316003B1 patent drawingFigure 3
  • EP3316003B1 patent drawingFigure 4

AI summary

A radiation measuring apparatus (20) includes a scatterer detector (10A), an absorber detector (10B) and a processing unit (12). Pixel electrodes (2) of the scatterer detector (10A) and the absorber detector (10B) are arranged such that a distance between centers of two neighbor pixel electrodes (2) is smaller than a mean free path of a recoil electron generated in the Compton scattering of an electromagnetic radiation. The processing unit (12) specifies an incidence direction of the electromagnetic radiation based on a recoiling direction to which the recoil electron recoils. In this way, an electron tracking-type Compton camera is realized which confines the incidence direction of the electromagnetic radiation by using the recoiling direction of the recoil electron in a Compton camera using a semiconductor detector.