Radiation Dose Correction via Segmented Ionization Currents

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Solution Overview

Problem

Conventional X-ray diagnostic apparatuses face inaccuracies in correcting radiation dose due to the interaction between X-rays and both air and solid objects, leading to excessive correction when using a gas state equation-based correction coefficient.

Innovation Solution

A radiation measuring instrument with an ionization chamber, barometer, and control unit that separates and corrects radiation dose information based on ionization currents caused by interactions between X-rays and air and solid electrodes, using distinct sensitivity ratios to account for the different influences of atmospheric pressure on gas and solid objects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a correction coefficient based on gas state equation is used to correct radiation dose, then correction can be performed, but the correction becomes excessive and inaccurate when ionization occurs from both air and solid objects

Engineering Contradiction:

Improveradiation dose correction accuracyVSAvoidcorrection calculation complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The total ionization current is segmented into two distinct components: first ionization current from air interaction and second ionization current from solid electrode interaction. This segmentation allows each component to be corrected with appropriate sensitivity ratios, preventing excessive correction while maintaining measurement accuracy.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different sensitivity ratios are applied to different ionization current components based on their local characteristics. The first sensitivity ratio applies to air-generated ionization current, while the second sensitivity ratio applies to solid electrode-generated ionization current, allowing precise correction tailored to each component's atmospheric pressure dependence.

Inventive Principle:

Principle #3Local quality

2Reliability

If atmospheric pressure correction is applied to total ionization current, then pressure effects are accounted for, but accuracy decreases when solid object ionization is present

Engineering Contradiction:

Improvecorrection reliabilityVSAvoidradiation dose measurement accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The ionization current is divided into air-component and solid-component, each corrected with appropriate sensitivity ratios. This ensures that only the air-component undergoes atmospheric pressure correction, while the solid-component remains uncorrected, maintaining measurement accuracy.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The correction approach changes from applying a single uniform sensitivity ratio to the total current to applying different sensitivity ratios to different current components. This parameter differentiation resolves the contradiction by matching the correction method to the physical characteristics of each ionization source.

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 allows for more accurate correction of radiation dose information by distinguishing between ionization currents generated by X-rays interacting with air and solid electrodes, reducing errors caused by excessive correction.

Implementation Method 1

an ionization chamber including an incident-side electrode provided at an incident port on which radiation is incident and an exit-side electrode provided at an exit port, the ionization chamber being configured to measure an ionization current generated by radiation transmitted through the incident-side electrode

Methodology Applied

Scientific EffectIonization: Ionisation

Implementation Method 2

a barometer configured to measure atmospheric pressure in the ionization chamber

Methodology Applied

Scientific EffectAtmospheric pressure measurement:

Implementation Method 3

a first ionization current caused by electrons generated by interaction between radiation and air

Methodology Applied

Scientific EffectInteraction between radiation and air:

Implementation Method 4

a second ionization current caused by electrons generated by interaction between the radiation and the incident-side electrode

Methodology Applied

Scientific EffectInteraction between radiation and solid electrode:

Data Source

PatentUS11073623B2Radiation measuring instrument and radiation imaging apparatus

Publication Date: 2021.07.27 SHIMADZU CORP

AI summary

The radiation measuring instrument is configured such that a control unit (12) corrects radiation dose information according to a measured value of a barometer (13) based on both a first ionization current caused by electrons generated by interaction between radiation and air and a second ionization current caused by electrons generated by interaction between the radiation and an incident-side electrode (11b).