Time-Gated Luminescence Measurement for Low Dose Detection
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Solution Overview
Problem
Existing luminescence dosimetry methods face challenges in achieving high signal-to-noise ratios due to unwanted background fluorescence from materials like lithium fluoride and polymers, which interferes with the measurement of ionizing radiation doses, especially at low doses.
Innovation Solution
The method involves using a fast light source, such as a laser or LED, to excite the material with pulses shorter than the decay time constant, allowing for time-gated measurement of luminescent emissions within a fixed time window to isolate and amplify the desired signal, while saturating and eliminating background fluorescence through peak-power excitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical stimulation is used to measure luminescence, then ionizing radiation dose can be measured, but background fluorescence from the material overlaps with the emission wavelengths and reduces signal-to-noise ratio
Solution Approach 1:
The measurement process is segmented into distinct time windows: an early time window to capture the luminescence signal and a later time window to measure and subtract background fluorescence. This temporal segmentation allows separation of the desired signal from the harmful background fluorescence that overlaps in wavelength.
Solution Approach 2:
The patent changes the temporal parameter of measurement by introducing time-resolved detection with specific time windows. By measuring at different time points (early vs. late) and subtracting the background component, the signal-to-noise ratio is improved while accounting for the overlapping background fluorescence.
2Measurement precision
If conventional OSL reading systems are used, then luminescence can be detected, but the minimum detectable dose remains relatively high due to background interference
Solution Approach 1:
The detection process is divided into sequential time windows where the first window captures the luminescence signal and the second window measures the background fluorescence. This segmentation enables detection of lower doses by separating the signal from the interfering background that would otherwise raise the minimum detectable dose.
Solution Approach 2:
The patent performs preliminary measurement of the background fluorescence level in a later time window before using it to correct the earlier luminescence measurement. This preliminary action allows for accurate subtraction of the background component, enabling detection of lower radiation doses.
3Illumination intensity
If blue light excitation is used to stimulate OSL, then luminescence emission can be generated, but unwanted non-ionizing radiation dose-dependent emission partially overlaps with the emission wavelengths of interest
Solution Approach 1:
The patent segments the emission detection in time, capturing the luminescence signal in an early time window and the unwanted background emission in a later time window. This temporal separation allows the use of intense blue light excitation while preventing the overlapping unwanted emission from interfering with the measurement.
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 approach significantly enhances the signal-to-noise ratio by rejecting unwanted background noise, enabling the detection of low ionizing radiation doses with improved accuracy and sensitivity, and can be applied to various luminescent materials, including lithium fluoride and polymers.
Implementation Method 1
a device or material is optically stimulated and then emits luminescence (photons) as a result of the optical stimulation that is proportional to the ionizing radiation dose
Implementation Method 2
Photons are detected using a sensitive light detector, such as a photomultiplier tube
Data Source
AI summary
A method of measuring luminescence of a material is disclosed. The method includes applying a light source to excite an exposed material. The method also includes amplifying an emission signal of the material. The method further includes measuring a luminescent emission at a fixed time window of about 10 picoseconds to about 10 nanoseconds. The luminescence may be radio photoluminescence (RPL) or optically stimulated luminescence (OSL).