Radiation Dosimeter Using Photon Event Counting for High Spatial Resolution
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Solution Overview
Problem
Existing radiation dosimeters face challenges in accurately measuring ionizing radiation dosage, particularly in small regions, due to the need for large scintillators and expensive electrical equipment, and struggle with low light emission levels requiring amplification and high-precision ammeters.
Innovation Solution
A radiation dosimeter comprising a small scintillator that converts ionizing radiation to light with minimal photoelectric effect emission, coupled with a photoelectric converter, counter, and dosage computing unit, which counts events exceeding a threshold and calculates dosage based on exponential event frequency, allowing for precise dosage detection using a small scintillator and simple circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the size of the scintillator is increased to increase the amount of light emission, then the measurement precision is improved, but the spatial resolution deteriorates
Solution Approach 1:
The patent changes the operating parameters by introducing a threshold value for light emission intensity and using exponential distribution modeling. This allows accurate dosage measurement with a small scintillator by counting events (photons) above the threshold rather than measuring total light emission, thus maintaining high spatial resolution while achieving measurement precision.
2Measurement precision
If the amplification factor is increased to measure small electric current, then the measurement precision is improved, but the device complexity and cost increase
Solution Approach 1:
The patent replaces the electrical amplification system with an optical counting system. Instead of measuring small electric currents through amplification, the system counts discrete photon events above a threshold using a photomultiplier tube and electronic counter. This substitution eliminates the need for high-precision ammeters and complex amplification circuits, reducing device complexity while maintaining measurement precision.
3Measurement precision
If a high-precision ammeter is used to measure small electric current, then the measurement precision is improved, but the cost increases
Solution Approach 1:
The patent uses a standard photomultiplier tube and electronic counter instead of expensive high-precision ammeters. By counting discrete photon events above a threshold, the system achieves measurement precision comparable to expensive equipment using inexpensive, readily available components, thus reducing manufacturing cost while maintaining measurement precision.
4Measurement precision
If the scintillator size is increased to increase light emission, then the measurement precision is improved, but the ease of operation in small regions deteriorates
Solution Approach 1:
The patent changes the measurement approach from continuous light emission measurement to discrete event counting with threshold filtering. This parameter change enables the use of small scintillators that can be easily positioned and operated in small regions while maintaining measurement precision through statistical counting methods.
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
Enables accurate and efficient detection of ionizing radiation dosage over a wide range with high spatial resolution and reduced equipment costs, achieving precise measurements comparable to high-performance ionization chambers.
Implementation Method 1
a scintillator which emits light by incident ionizing radiation
Implementation Method 2
a photoelectric converter which converts light, which is output from the scintillator, to an electric current
Data Source
AI summary
Light emitted in correspondence to ionizing radiation incident from a scintillator is fed through an optical fiber to a photoelectron multiplier tube by which it is converted to an electrical signal. The electrical signal is amplified by a signal amplifying circuit, and any light emission events of given or higher intensity are discriminated by a discriminator and counted by a counter. The count value is fed to a computer. The computer converts the count value to a dosage on the basis of an exponential relationship lying between the light emission intensity and the number of emission events, thereby attaining detection of the dosage.