Water Phantom With 2D Detector Matrix for Rapid Dose Mapping

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Solution Overview

Problem

Conventional water phantoms for radiation therapy are time-consuming and cumbersome, unable to efficiently measure dose distribution, especially for time-dependent radiation fields and shallow depths, due to mechanical scanning and large size, which limits their application in commissioning and quality assurance tests.

Innovation Solution

A water phantom with a two-dimensional acquisition detector comprising multiple sensors fixed outside the water tank, allowing simultaneous measurement of dose distribution across a defined area, and a bi-directional pumping system for varying water levels, maintaining constant source-to-water phantom surface distance, eliminating the need for mechanical positioning devices.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a single point detector is moved sequentially through the radiation field, then the measurement can be performed with simple detector construction, but the measurement time becomes excessively long and the system cannot measure time-dependent radiation fields

Engineering Contradiction:
Improvemeasurement speedVSAvoiddetector construction complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The invention transitions from a one-dimensional linear array of detectors to a two-dimensional matrix array of detectors. This dimensional expansion allows simultaneous measurement across the entire radiation field cross-section, reducing measurement time from sequential point-by-point scanning to a single comprehensive measurement plane.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The radiation field measurement is segmented into multiple independent detector elements arranged in a two-dimensional matrix. Each detector element measures radiation dose at its specific location simultaneously, eliminating the need for mechanical scanning and enabling rapid acquisition of the complete dose distribution map.

Inventive Principle:
Principle #1Segmentation

2Ease of operation

If a large water volume phantom is used with mechanical scanning, then comprehensive dose mapping is achieved, but the phantom becomes cumbersome and cannot be positioned on the patient couch

Engineering Contradiction:
Improvepositioning capabilityVSAvoidwater phantom volume
Core Design Contradiction:
Ease of operationVSVolume of stationary object

Solution Approach 1:

The invention replaces the mechanical scanning system with an electronically controlled two-dimensional detector matrix. This eliminates heavy mechanical positioning mechanisms, reducing the phantom's weight and complexity enough to allow placement on the patient couch for in-situ measurements.

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

Solution Approach 2:

By expanding from linear to two-dimensional detector arrangement, the measurement capability is dramatically increased without proportionally increasing the water phantom volume. The detector matrix captures the entire radiation field cross-section simultaneously, reducing the required water volume compared to sequential scanning methods.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Measurement precision

If mechanical positioning devices are used for detector movement, then precise positioning is achieved, but the system complexity and measurement time increase

Engineering Contradiction:
Improvepositioning precisionVSAvoidmeasurement time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The positioning function is segmented across multiple fixed detector elements in a two-dimensional matrix, each precisely positioned at known coordinates. This eliminates the need for mechanical movement and timing synchronization, achieving both high positioning precision and rapid simultaneous measurement across the entire field.

Inventive Principle:
Principle #1Segmentation

4Measurement precision

If ionization chambers are used as detectors, then accurate radiation dose measurement is achieved, but water resistance construction becomes problematic

Engineering Contradiction:
Improvedose measurement accuracyVSAvoiddetector construction complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The invention uses diode detectors that replicate the radiation detection function of ionization chambers but with solid-state construction inherently resistant to water. The diodes provide comparable dose measurement accuracy without requiring complex water-tight sealing mechanisms.

Inventive Principle:
Principle #26Copying

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

Significantly reduces the time required for commissioning and quality assurance tests, enabling faster and more precise measurement of radiation fields, allowing for more frequent and comprehensive testing, and enabling the phantom to be positioned on a patient couch for improved positioning control.

Implementation Method 1

The acquisition detector is a two-dimensional detector comprising a plurality of sensors for simultaneously measuring the dose in a plurality of points in an area

Methodology Applied
Scientific EffectIonization: Ionisation

Data Source

PatentEP2016445B1Water phantom
Publication Date: 2013.10.02 ION BEAM APPL
  • EP2016445B1 patent drawingFigure 1a
  • EP2016445B1 patent drawingFigure 1b
  • EP2016445B1 patent drawingFigure 2

AI summary

The present invention is related to a water phantom for measuring and determining the dose distribution of radiation produced by a particle beam or photon radiation beam comprising: a water tank; means for varying the water level in said water tank; an acquisition detector positioned in a fixed position related to the water tank opposite to the beam, wherein said acquisition detector is a two dimensional detector comprising a plurality of sensors and capable of simultaneously measuring the dose in a plurality of points in an area. Subsequent measurements are performed varying each time the water level within the water tank, until the dose distribution in the entire volume of the water tank is obtained.