Prompt Gamma Ray Detector for Real-Time Hadrontherapy Dose Monitoring
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Solution Overview
Problem
Current methods for measuring dose distribution during hadrontherapy are primarily a posteriori and lack real-time capabilities, making it difficult to monitor the treatment effectively, and existing devices are bulky and inefficient due to the need for extensive protection layers to filter neutrons and gamma rays.
Innovation Solution
A method and device utilizing a detector with energy and time-of-flight measurement means to discriminate between prompt gamma rays and neutrons by their propagation speed, combined with a bidirectional system for charged particle detection to provide real-time, two- or three-dimensional dose measurement, allowing for the elimination of unnecessary protection layers and enabling easy handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If extensive protection layers (paraffin wax, B4C powder, lead) are used to filter neutrons and gamma rays, then measurement reliability is improved, but device size and complexity increase significantly
Solution Approach 1:
The patent changes the detection parameter from measuring neutron capture gamma rays (requiring thick shielding) to directly measuring prompt gamma rays emitted during nuclear fragmentation. This parameter change eliminates the need for extensive protection layers while maintaining measurement reliability, as the detector can be positioned at a distance L to receive prompt gamma rays without requiring paraffin wax, B4C powder, or lead shielding.
2Reliability
If extensive protection layers are used to filter neutrons and gamma rays, then measurement reliability is improved, but ease of operation deteriorates due to bulky apparatus
Solution Approach 1:
By changing the detection parameter to measure prompt gamma rays directly, the patent eliminates the need for bulky protection layers, making the apparatus compact and easy to operate while maintaining measurement reliability through distance-based discrimination.
3Measurement precision
If position emission tomography (PET) techniques are used to measure dose distribution, then measurement precision is improved, but real-time measurement capability is lost
Solution Approach 1:
The patent detects prompt gamma rays that are emitted immediately during the nuclear fragmentation process, providing real-time information about the dose distribution as the treatment is being delivered. This preliminary detection during the actual treatment process eliminates the need for a posteriori PET measurements, enabling both precise and real-time monitoring.
4Measurement precision
If the detector is positioned close to the target to improve measurement sensitivity, then measurement precision is improved, but discrimination between prompt gamma rays and neutrons becomes difficult
Solution Approach 1:
The patent uses time-of-flight measurement to distinguish between prompt gamma rays and neutrons based on their different velocities. By measuring the time it takes for particles to travel from the target to the detector, the system can reliably discriminate between gamma rays (arriving first) and neutrons (arriving later), even when the detector is positioned at an optimized distance.
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 allows for a compact, easy-to-handle device that provides precise, real-time measurement of local doses during hadrontherapy, enabling effective treatment control by correlating prompt gamma ray distribution with dose distribution, thereby improving treatment precision and reducing equipment size.
Implementation Method 1
a detector at a distance L from the region to be measured of the target, chosen so as to make it possible to discriminate the prompt gamma rays from the neutrons by virtue of their difference in propagation speed
Implementation Method 2
the bombardment of said target by a beam of incident hadrons which leads to a nuclear fragmentation in said target and generates at least prompt gamma radiations and neutrons
Data Source
AI summary
A method for real-time measurement of a local dose received by a region of a target upon bombardment of the target by an incident beam of hadrons generates at least prompt gamma rays and neutrons. The particles emitted by the target are measured by collimating the region of the target and by placing a detector at a distance L from the region of the target to be measured. The detector is linked to a device for particle energy and time-of-flight measurement, in which the number of prompt gamma rays received by the detector is determined by selecting the recorded events, and a two-directional charged-particle detection system, placed in the beam of incident hadrons before the target, is used so as to obtain the transverse position of the incident hadrons in order to provide spatial information about the prompt gamma rays.