X-ray Source Cathode Consumption Estimation via Tube Current Timing

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Solution Overview

Problem

Conventional X-ray imaging apparatuses face difficulties in measuring the grid voltage externally, making it impossible to estimate the cathode consumption level without direct access to the grid electrode, which is typically located inside the X-ray tube.

Innovation Solution

The apparatus employs a feedback control system to maintain a set tube current value by adjusting the grid voltage, and includes a time measurement component to estimate cathode consumption based on the time it takes for the tube current to reach the set value, eliminating the need for external grid voltage measurement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If grid voltage is measured externally to determine cathode consumption level, then measurement precision is improved, but device complexity increases and ease of operation deteriorates due to requiring internal access to grid electrode

Engineering Contradiction:

Improvecathode consumption level measurementVSAvoidexternal measurement accessibility

Core Design Contradiction:

Measurement precisionVSEase of operation

Solution Approach 1:

The patent uses tube current value as an intermediary parameter to indirectly assess cathode consumption level. Instead of directly measuring grid voltage which requires internal access, the system measures tube current value externally and uses it as a proxy indicator for cathode consumption, thereby resolving the accessibility problem while maintaining measurement capability

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the physical measurement approach (direct grid voltage measurement requiring internal access) with an electrical measurement approach (tube current value measurement that can be performed externally). This substitution allows the same diagnostic function to be achieved without mechanical intervention inside the X-ray tube

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of operation

If grid voltage is measured from outside the X-ray tube, then ease of operation is improved, but measurement precision deteriorates due to inability to directly access grid electrode voltage

Engineering Contradiction:

Improveexternal measurement accessibilityVSAvoidcathode consumption level measurement

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The patent creates a functional copy of the grid voltage measurement capability by measuring tube current value instead. The tube current value serves as a surrogate that correlates with cathode consumption level, allowing external measurement while preserving the diagnostic information needed for consumption assessment

Inventive Principle:

Principle #26Copying

3Ease of operation

If time measurement method is used to estimate cathode consumption, then ease of operation is improved, but measurement precision may deteriorate compared to direct grid voltage measurement

Engineering Contradiction:

Improveconsumption level estimationVSAvoidconsumption level estimation accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The patent changes the measurement parameter from grid voltage to tube current value and its temporal characteristics. By measuring how long it takes for tube current to reach a steady state value after being set, the system obtains a temporal parameter that correlates with cathode consumption level, making the measurement easier to perform externally

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 method allows for accurate estimation of cathode consumption without measuring the grid voltage, enabling timely alerts and precise monitoring of cathode aging, thus improving the operational efficiency of the X-ray source.

Implementation Method 1

an X-ray source that gives high voltage between a cathode and a target

Methodology Applied

Scientific EffectThermionic emission: Thermionic Emission

Implementation Method 2

an X-ray imaging apparatus including an X-ray source

Methodology Applied

Scientific EffectElectromagnetic radiation: X-Ray

Implementation Method 3

keeps a tube current value at a set value by performing feedback control of grid voltage given to a grid disposed between the cathode and the target

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS11450502B2X-ray imaging apparatus and consumption level estimation method for X-ray source

Publication Date: 2022.09.20 SHIMADZU CORP

AI summary

An X-ray imaging apparatus and a consumption level estimation method for an X-ray source, which estimate the consumption level of an X-ray source without measuring grid voltage. An X-ray control part includes: a tube current value setting part setting a tube current value supplied to an X-ray source; a tube current value measurement part measuring a cathode current value as the tube current value by a cathode current detector; a time measurement part measuring the time when the tube current value is set by the tube current value setting part and the time when the tube current value measured by the tube current value measurement part reaches the set value; and a consumption level estimation part estimating the consumption level of a cathode in the X-ray source based one the time until the tube current value reaches the set value after the tube current value has been set.