Radiotherapy Source Rotation for Patient Position Correction

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Solution Overview

Problem

Current radiotherapy systems with 6 degrees of freedom patient tables are costly and cumbersome, and patient rotation around horizontal axes can cause positional deviations due to gravity effects, necessitating a more efficient alignment method.

Innovation Solution

A radiotherapy apparatus with a radiation source that rotates within a limited range, allowing for patient position correction by offsetting the source's rotation based on imaging device feedback, eliminating the need for patient table rotational adjustments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a patient table with 6 degrees of freedom is used to correct patient position, then positioning accuracy is improved, but device complexity and cost increase

Engineering Contradiction:

Improvepositioning accuracyVSAvoiddevice complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The invention extracts the rotational correction function from the patient table and relocates it to the radiation source. By allowing the source to rotate within a limited range around an axis intersecting the beam, the system achieves patient positioning correction without requiring the patient table to have rotational capabilities, thereby reducing table complexity while maintaining positioning accuracy

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of rotating the patient table to correct patient position, the invention inverts the approach by rotating the radiation source. This inversion allows the source to sweep across a limited angular range to accommodate patient rotational deviations, achieving the same positioning correction goal with a simpler patient table design

Inventive Principle:

Principle #13The other way round (Inversion)

2Adaptability or versatility

If the patient table volume and supporting structure are increased to provide multiple degrees of freedom, then positioning capability is improved, but clearance problems occur during treatment

Engineering Contradiction:

Improvepositioning capabilityVSAvoidclearance space

Core Design Contradiction:

Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The invention removes the need for rotational adjustment mechanisms from the patient table by extracting this function and assigning it to the radiation source. This extraction allows the patient table to maintain a compact design with sufficient clearance space, while still achieving the required positioning capability through source rotation

Inventive Principle:

Principle #2Taking out (Extraction)

3Measurement precision

If the patient is rotated on the table around horizontal axes, then positioning accuracy is improved, but patient comfort deteriorates and positional deviations occur due to gravity

Engineering Contradiction:

Improvepositioning accuracyVSAvoidpatient comfort and positional deviations

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The invention inverts the traditional approach by instead of rotating the patient, it rotates the radiation source. This inversion eliminates the harmful effects of patient rotation such as discomfort and gravity-induced positional deviations, while still achieving positioning accuracy through the source's limited angular rotation range

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The invention converts the limitation of the radiation source's rotation range into a benefit by using it to define a safe operating envelope. The source rotation range is specifically configured to accommodate patient rotational deviations without requiring actual patient rotation, thereby converting the constraint into a solution that maintains patient comfort while achieving positioning accuracy

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Data Source

PatentUS10391336B2Image guided radiotherapy with adjusted angular range of source

Publication Date: 2019.08.27 ELEKTA AB

AI summary

An apparatus comprises a radiotherapy delivery apparatus having a radiation source for emitting a beam of radiation and wherein the source is rotatable around an axis intersecting the beam through a range of at least x degrees, an imaging device, and a control unit controlling the source and imaging device. The apparatus further comprises a treatment planning computer receiving a first image of a patient, and parameters defining the operations of the radiotherapy delivery apparatus. Parameters include an available range of rotation for the source, x-e, where e>0. The treatment planning computer generates a treatment plan for the patient based on the received image and parameters. The control unit determines a patient position using the imaging device, determines a rotation r of the patient around the axis relative to the first image, and compensates for the rotation by offsetting the source by a rotation, r, when r<e.