Composite Scintillator Detector for Depth-Resolved Dose Measurement
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Solution Overview
Problem
Current detectors for quality assurance in charged particle therapy lack sufficient spatial resolution and dosimetric accuracy to accurately measure the delivered dose as a function of depth, leading to incomplete confidence in matching the delivered beam with the treatment plan, especially for complex radiotherapy treatments like IMPT.
Innovation Solution
A detector system comprising a scintillating screen with a mixture of scintillators emitting different spectra, combined with high-resolution imaging sensors and variable optics, to produce an output proportional to the dose deposited as a function of depth within a tissue phantom, ensuring accurate measurement of the radiation beam's spatial distribution and intensity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single scintillator material is used in the detector, then the device complexity is reduced, but the measurement precision of dose as a function of depth is insufficient
Solution Approach 1:
The patent employs a composite scintillator material comprising multiple scintillator components with different emission spectra and depth-dependent responses. This composite approach enables the detector to accurately measure dose as a function of depth by combining the complementary characteristics of each scintillator material, thereby achieving high measurement precision without requiring overly complex device architecture.
Solution Approach 2:
The scintillator layer is segmented into multiple distinct scintillator materials, each contributing to measuring dose at different depths. By segmenting the scintillator composition rather than using a single homogeneous material, the system achieves depth-resolved dose measurement capability while maintaining a relatively simple overall detector structure.
2Measurement precision
If high-resolution imaging sensors are used, then the spatial resolution is improved, but the device complexity and cost increase
Solution Approach 1:
The patent replaces complex mechanical scanning or multiple physical detectors with a high-resolution imaging sensor that captures the entire beam profile simultaneously. This substitution of mechanical or sequential measurement systems with a parallel optical imaging system achieves high spatial resolution while simplifying the overall device architecture and reducing moving parts.
3Measurement precision
If the scintillator emits a single spectrum of light, then the manufacturing is simplified, but the dosimetric accuracy for different beam energies is reduced
Solution Approach 1:
The scintillator is fabricated as a composite material containing multiple phosphor components with different emission spectra. While this composite approach enhances dosimetric accuracy across different beam energies by providing energy-dependent spectral information, the manufacturing process remains relatively straightforward by utilizing conventional phosphor mixing and encapsulation techniques.
Solution Approach 2:
The patent utilizes changes in the spectral parameters of the scintillator emission to encode depth and energy information. By carefully selecting scintillator materials with specific emission wavelengths and decay characteristics, the system achieves accurate dose measurement across different beam energies without requiring complex fabrication processes.
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
The system provides high spatial resolution and dosimetric accuracy, enabling precise validation of treatment plans by generating images of the beam distribution that are proportional to the desired characteristics, such as absorbed dose, thereby enhancing the confidence in delivering the intended radiation dose.
Implementation Method 1
a scintillating screen disposed behind the tissue phantom for emitting light in response to the radiation
Data Source
AI summary
An apparatus and method are provided for performing Quality Assurance of complex beams of penetrating radiation inside a patient. A detector with a transverse scintillating screen images the radiation inside a tissue phantom with high spatial resolution. The scintillator is comprised of a mixture of two or more scintillators emitting different spectra of light and having different characteristic responses as a function of the beam LET value. The optics relaying the scintillation output have variable transmission with wavelength, further shaping the spectrum of light transmitted to the imaging sensor which also has spectrally varying sensitivity. Parameters of the scintillator construction, the optics, and the imaging sensor are chosen so the output of the composite detector is proportional to a characteristic of the input beam, for example the dose deposited as a function of depth inside the tissue phantom.