Radiotherapy Controller Gantry Sagging Compensation

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Solution Overview

Problem

Radiotherapy apparatuses face challenges in accurately positioning the irradiation target and conducting positioning accuracy testing due to sagging supporting structures, which result in erroneous visual fields and reduced positioning accuracy.

Innovation Solution

A radiotherapy apparatus controller that includes a portal image taking unit, gantry position collector, marker position calculator, and marker position table generator to accurately correlate gantry positions with marker positions, ensuring precise positioning and accuracy testing by using a marker position table.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the supporting structure is moved, then the therapeutic radiation radiating device can be repositioned, but the visual field deviates from the desirable visual field due to sagging

Engineering Contradiction:

Improverepositioning capabilityVSAvoidvisual field accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The system uses transmission images to detect the actual position of the visual field, compares it with the desirable position, and automatically calculates correction amounts to compensate for sagging-induced deviations, enabling accurate repositioning despite structural deformation

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system changes the parameter representation by introducing a marker position table that correlates gantry positions with actual marker positions on transmission images, allowing the system to account for and compensate for position deviations caused by sagging

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If the gantry position is changed, then different viewing angles are achieved, but the marker position on the transmission image shifts due to supporting structure sagging

Engineering Contradiction:

Improveviewing angle flexibilityVSAvoidmarker position accuracy

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The system creates a virtual copy of the marker position relationship through the marker position table, which stores the correspondence between gantry positions and marker positions on transmission images, allowing accurate position prediction and compensation without physical repositioning errors

Inventive Principle:

Principle #26Copying

3Measurement precision

If the supporting structure is made more robust to prevent sagging, then positioning accuracy improves, but the device complexity and weight increase

Engineering Contradiction:

Improvepositioning accuracyVSAvoidsupporting structure complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The system replaces mechanical reinforcement of the supporting structure with a computational solution using transmission images and marker position tables to detect and correct for sagging effects, achieving positioning accuracy without increasing structural complexity or weight

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 solution allows users to accurately recognize the region projected on the transmission image, thereby verifying the positional relation between radiation and the target, ensuring accurate radiation delivery even when the gantry moves, thus enhancing the precision of the radiotherapy process.

Implementation Method 1

a portal image taking unit configured to take a first transmission image, in which a marker member positioned at a predetermined position is shown, by using therapeutic radiation and an imager

Methodology Applied

Scientific EffectTherapeutic radiation transmission and detection: X-Ray

Data Source

PatentUS8005190B2Radiotherapy apparatus controller and irradiation method

Publication Date: 2011.08.23 HITACHI HIGH TECH CORP

AI summary

A radiotherapy apparatus controller includes: a portal image taking unit; a gantry position collector; a marker position calculator; and a marker position table generator. The portal image taking unit takes a first transmission image, in which a marker member positioned at a predetermined position is shown, by using therapeutic radiation and an imager. The gantry position collector collects a first gantry position at which a gantry is positioned when the first transmission image is taken from a sensor measuring a position at which the gantry is positioned, the gantry supporting the imager and a therapeutic radiation radiating device which radiates the therapeutic radiation. The marker position calculator calculates a first marker position at which the marker member is shown in the first transmission image. The marker position table generator updates a marker position table, which correlates a plurality of gantry positions with a plurality of marker positions, so that the first gantry position corresponds to the first marker position.