Scattering Radiation Detector for Radiotherapy Dose Verification
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Solution Overview
Problem
Current external X-ray radiation therapy lacks means to confirm if the planned irradiation is accurately delivered to the patient, leading to potential excessive or insufficient irradiation, especially with advancements in precise tumor tracking and beam collimation, necessitating a method to prevent damage to normal tissues.
Innovation Solution
A radiotherapeutic system that measures scattering radiation to objectively determine the irradiated region and dose distribution using a detector with a collimator, rotating to capture scattering radiation from various angles and reconstructing a three-dimensional distribution of scattering events, converting this data into absorbed dose images for real-time monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a phantom and X-ray detector are used to confirm planned irradiation before treatment, then irradiation accuracy can be verified, but it is difficult to place the patient in the same position as the phantom and the confirmation does not completely assure planned irradiation to the patient
Solution Approach 1:
The patent implements real-time feedback by detecting scattering radiation from the patient's body during irradiation and reconstructing the actual dose distribution. This allows immediate verification whether the irradiation is being delivered as planned, enabling corrective actions if deviations are detected, thus ensuring reliable execution of the irradiation plan.
Solution Approach 2:
The patent introduces scattering radiation detection as an intermediary measurement method. Instead of directly measuring the therapeutic X-ray beam (which has limited width and passes through the body), the system detects scattered radiation that provides information about the actual dose distribution, serving as a mediator to verify irradiation accuracy.
2Manufacturing precision
If precise tumor tracking and beam collimation methods are used to concentrate dose to affected region, then treatment precision is improved, but normal tissue damage risk increases if the beam is off from the target
Solution Approach 1:
The system provides real-time feedback on the actual dose distribution by detecting scattering radiation during irradiation. This allows verification that the high-precision beam delivery is accurately targeting the tumor and not inadvertently damaging surrounding normal tissues, enabling immediate correction if misalignment occurs.
Solution Approach 2:
The patent performs preliminary verification of the irradiation setup by detecting scattering radiation before and during treatment. This preliminary action confirms that the precise beam collimation is correctly positioned, preventing normal tissue damage before it occurs.
3Difficulty of detecting and measuring
If scattering radiation detection is performed in the incident X-ray direction, then scattering radiation can be detected, but it is difficult to distinguish scattering radiation from penetrating radiation
Solution Approach 1:
The patent applies local quality by using different detection strategies for different spatial regions. In the forward direction (incident X-ray direction), the system accepts that both scattering and penetrating radiation are detected but uses this information appropriately. In other directions, primarily scattering radiation is detected with better discrimination capability.
Solution Approach 2:
The system changes the detection parameter (detector position angle) to optimize measurement. By detecting scattering radiation at various angles relative to the incident beam direction, the system can distinguish scattering from penetrating radiation based on the angular distribution characteristics, improving measurement precision.
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 verification of radiation treatment adherence to the plan, preventing excessive irradiation to normal tissues and ensuring precise dose delivery, thereby improving treatment efficacy and reducing exposure risks.
Implementation Method 1
measuring an actually irradiated region in the patient and actual dose by using a technique of acquiring a cross-sectional image by using scattering radiation
Data Source
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AI summary
A detector (301) having a collimator (303) in a position at a specific angle with respect to a therapeutic X-ray beam is mounted to selectively detect only scattering radiation in the direction. To three-dimensionally obtain a distribution of places where scattering occurs in a patient body, a detector (301) is rotated during irradiation and scattering radiation is measured from all of directions. After that, a reconstructing process is performed, and a distribution of occurrence of scattering radiation in the subject is three-dimensionally imaged. Since angles and amounts of X-rays scattered by Compton scattering are known theoretically, if scattering radiation at a certain angle can be detected, the number of scattering radiation at other angles can be also estimated. On the basis of the theory, images of distribution of scattering radiation sources are converted to images of distribution of absorption of radiation.