Radiotherapy Apparatus Dose Stabilization via Feedback Control

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Solution Overview

Problem

Current radiotherapy apparatuses face challenges in maintaining a high stability of radiation doses, particularly for treating tumors in areas like the prostate and lung, where dose fluctuations are significant, affecting the accuracy and effectiveness of the treatment.

Innovation Solution

The radiotherapy apparatus incorporates a control unit with a transmission type dosimeter and sensor arrays to monitor and adjust the electron beam's energy, ensuring a consistent dose distribution by controlling the electric current and high-frequency power, thereby stabilizing the therapeutic radiation's absorption dose at the treatment site.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional radiotherapy apparatus is used, then radiation treatment can be performed, but dose fluctuation is significant affecting treatment accuracy

Engineering Contradiction:
Improvedose stabilityVSAvoidtreatment accuracy
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent implements a feedback control system where a transmission-type dosimeter continuously measures the actual radiation dose delivered to the patient. The control unit compares the measured dose with the prescribed dose and automatically adjusts the electron beam parameters (acceleration voltage, beam current) to compensate for deviations, thereby stabilizing the delivered dose and improving treatment reliability

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent replaces manual dose monitoring and adjustment procedures with an automated electronic control system. The transmission-type dosimeter coupled with the control unit creates an electronic feedback loop that continuously monitors and adjusts beam parameters, substituting mechanical/manual operations with electronic automation to achieve superior dose stability

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

2Manufacturing precision

If electron beam energy is not controlled, then treatment can proceed quickly, but dose distribution becomes inconsistent

Engineering Contradiction:
Improvedose distribution uniformityVSAvoidtreatment efficiency
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The patent performs preliminary calibration and setup of the electron beam parameters before treatment begins. The system pre-establishes the relationship between acceleration voltage, beam current, and resulting dose distribution, allowing for rapid automated adjustments during treatment without requiring manual recalibration, thus maintaining both precision and efficiency

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The real-time feedback from the transmission-type dosimeter enables continuous monitoring of dose distribution uniformity. The control unit automatically adjusts electron beam parameters based on measured deviations, maintaining consistent dose distribution throughout the treatment process without manual intervention, thereby preserving treatment efficiency while ensuring dose precision

Inventive Principle:
Principle #23Feedback

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 dose fluctuations, allowing for precise and accurate delivery of a predetermined therapeutic radiation dose to the affected region, enhancing treatment efficacy and stability.

Implementation Method 1

a transmission type dosimeter 56...measure a dose of the radiation transmitted the transmission type dosimeter 56

Methodology Applied
Scientific EffectRadiation attenuation: Absorption (EM radiation)

Implementation Method 2

a sensor 57...measures an electric current flowing through the target 53

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 3

an irradiating head 16...generate a therapeutic radiation 23...a target 53...converts an electron beam into the X-ray

Methodology Applied
Scientific EffectBremsstrahlung radiation: X-Ray

Data Source

PatentEP2151262B1Radiotherapy apparatus and radiation irradiating method
Publication Date: 2011.04.27 MITSUBISHI HEAVY IND LTD
  • EP2151262B1 patent drawingFigure 1
  • EP2151262B1 patent drawingFigure 2
  • EP2151262B1 patent drawingFigure 3

AI summary

A radiotherapy apparatus includes an acceleration unit configured to generate a charged particle beam. A target is configured to generate a radiation when the charged particle beam is irradiated to the target. A sensor is configured to measure an electric current flowing through the target. A dosimeter is configured to measure a dose of the radiation. A control unit is configured to control the acceleration unit based on the measured electric current and the measured dose.