Scintillation Imaging System for High Spatiotemporal Dosimetry
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Solution Overview
Problem
Current dosimetry methods for proton therapy are limited by low spatial resolution and inability to measure proton range and spot characteristics on a pulse-by-pulse basis, particularly for ultra-high dose rate radiation beams like those used in FLASH-RT, which require high spatiotemporal resolution for accurate dosimetry.
Innovation Solution
A scintillation imaging system utilizing a plastic scintillator detector and high-speed CMOS cameras synchronized with the radiation beam pulse train, capable of capturing scintillation images for each pulse, with a retractable mirror for dual-camera setup to measure range and spot intensity/position, and a computer-implemented algorithm to correct for ionization quenching and background noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ionization chamber arrays are used for depth dose measurements, then dosimetry can be performed, but spatial resolution is limited to several millimeters
Solution Approach 1:
The patent replaces mechanical ionization chamber arrays with a scintillation screen coupled to a digital camera system. The scintillation screen converts radiation interactions into optical signals that are captured by the camera, eliminating the need for complex mechanical chamber arrays while achieving superior spatial resolution of 0.5 mm or better.
Solution Approach 2:
The patent uses a scintillation screen that creates an optical copy of the radiation distribution pattern. This optical image is then captured by a digital camera, allowing the radiation dose distribution to be visualized and measured with high spatial resolution without directly measuring each point mechanically.
2Measurement precision
If conventional dosimeters are used for FLASH-RT, then dosimetry can be performed, but temporal resolution is insufficient for ultra-high dose rate beams
Solution Approach 1:
The patent employs a pulsed illumination scheme where the scintillation screen is excited by the radiation beam in periodic pulses. The digital camera captures images synchronized with these pulses, allowing temporal resolution matched to the pulse frequency. This enables measurement of ultra-high dose rate FLASH beams by capturing each pulse separately.
Solution Approach 2:
The patent maintains continuous measurement capability by using a high-speed digital camera that can capture images at frequencies matching the radiation pulse train. This continuous capture process ensures no loss of temporal information, allowing complete characterization of ultra-high dose rate beams throughout the treatment delivery.
3Measurement precision
If scintillation imaging is used for high spatiotemporal resolution dosimetry, then pulse-by-pulse measurement is enabled, but Cherenkov radiation interference occurs for electron and photon beams
Solution Approach 1:
The patent extracts only the scintillation signal from the total light output by using time-gated detection. The camera is synchronized to capture light only during the specific time window when scintillation occurs, excluding the earlier Cherenkov radiation. This temporal filtering separates the desired scintillation signal from the harmful Cherenkov background.
Solution Approach 2:
The patent skips the Cherenkov radiation time window by using fast gating that opens only after the Cherenkov emission has ceased. The camera shutter is timed to close during the Cherenkov phase and open during the scintillation phase, effectively rushing through the harmful period and capturing only the useful signal.
4Measurement precision
If parallel-plate ionization chamber arrays are used for proton range measurement, then depth dose curves can be obtained, but measurements cannot be performed on a pulse-by-pulse basis
Solution Approach 1:
The patent replaces the mechanical ionization chamber array with a scintillation screen and digital camera system. This substitution enables the system to capture images at high frame rates synchronized with the radiation pulse train, allowing pulse-by-pulse measurement capability that mechanical chambers cannot achieve.
Solution Approach 2:
The patent creates an optical copy of each radiation pulse using the scintillation screen. Each pulse produces a light pattern that is captured by the camera, creating a visual record of each individual pulse. This copying mechanism enables retrospective analysis of each pulse's characteristics without requiring complex real-time mechanical adjustments.
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 achieves high spatial and temporal resolution dosimetry, enabling accurate measurement of proton beam range, spot size, and position on a pulse-by-pulse basis, improving the precision of proton therapy and potentially replacing existing devices like Zebra and Lynx, while being cost-effective and efficient for QA.
Implementation Method 1
A scintillation imaging system utilizing a plastic scintillator detector and high-speed CMOS cameras synchronized with the radiation beam pulse train, capable of capturing scintillation images for each pulse
Implementation Method 2
with a retractable mirror for dual-camera setup to measure range and spot intensity/position
Data Source
AI summary
The present disclosure provides systems and methods for radio-luminescent imaging dosimetry of variable dose rate radiation beams at high spatial resolution. Exemplary embodiments include time-gating one or more camera shutters such that one image frame from a plastic scintillator detector (PSD) is captured per camera shutter for each radiation beam pulse produced from a pulsed beam accelerator directed toward the PSD.