X-ray Detector Dead Time Measurement Using Absorption Foils
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Solution Overview
Problem
Conventional methods for determining the dead time of a pulse type X-ray detector require estimation of true X-ray intensity, which is time-consuming and lacks accuracy, especially when using tube current variations, and may not account for proportional changes in X-ray intensity due to optical devices.
Innovation Solution
A method involving multiple setting states for the X-ray path conditions, such as varying slit widths or absorption plate presence, to observe X-ray intensities under different conditions, allowing for the determination of dead time using relational expressions and the least squares method without estimating true X-ray intensity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional methods using tube current variations are used to determine dead time, then dead time can be determined, but the process is time-consuming and lacks accuracy due to the need to wait for X-ray intensity stabilization and potential proportional changes
Solution Approach 1:
The patent changes the approach from varying tube current to varying absorption conditions using metal foils. By changing the absorption parameter (number of foils) rather than the source intensity parameter (tube current), the method eliminates stabilization waiting time and achieves more accurate dead time measurement through direct observation of counting loss at different absorption levels.
2Measurement precision
If tube current is varied to estimate true X-ray intensity, then dead time determination is possible, but accuracy is compromised because X-ray intensity may not change proportionally with tube current due to optical device effects
Solution Approach 1:
The patent introduces metal foils as an intermediary element between the X-ray source and detector. By placing known absorption materials in the X-ray path, the method creates a reliable and controllable attenuation effect that is independent of tube current variations and optical device characteristics, providing accurate true intensity estimation through the relationship between absorption and detected intensity.
3Measurement precision
If the number of nesting in calculation is increased to improve accuracy of true X-ray intensity calculation, then calculation accuracy improves, but calculation complexity increases
Solution Approach 1:
The patent applies partial action by using a limited number of metal foils (typically 3-10 foils) instead of requiring extensive calculation nesting. This provides sufficient accuracy for dead time determination without the need for complex iterative calculations, achieving an optimal balance between measurement precision and practical simplicity.
Data Source
AI summary
The dead time of a pulse type X-ray detector is measured without estimation of a true X-ray intensity. The first and the second conditions are used for varying an intensity of an X-ray entering the X-ray detector. The first condition may be the slit width of a receiving slit, at least three kinds of slit width being selected. The second condition may be with or without an absorption plate. The first observed X-ray intensities are observed, with the absorption plate inserted, for three or more values in slit width. Next, the second observed X-ray intensities are observed similarly but with the absorption plate removed. A predetermined relational expression is made up among the first observed X-ray intensity, the second observed X-ray intensity, a ratio k of the second observed X-ray intensity to the first observed X-ray intensity (depending upon attenuation in X-ray intensity caused by the absorption plate) and the dead time τ of the X-ray detector. Based on the relational expression, a fitting operation is carried out with the least squares method so as to determine the dead time τ precisely.