PET Activity Distribution Evaluation for Moving Targets
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Solution Overview
Problem
Current methods fail to accurately monitor and evaluate the activity distribution and dose distribution in moving target objects during particle therapy due to movement-induced fuzziness, which prevents precise reconstruction of the deposited dose distribution.
Innovation Solution
An apparatus comprising a positron emission tomograph, a movement detection device, and an evaluation unit that associates photon measurement data with the movement signal to correct for target object movement, allowing for a three-dimensional evaluation of the activity distribution and dose distribution in moving targets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a scanned particle beam is used to irradiate moving target volumes, then the dose application precision is improved, but the ability to accurately monitor and evaluate the activity distribution deteriorates due to movement-induced fuzziness
Solution Approach 1:
The patent applies preliminary action by recording the movement of the target object during irradiation and using this recorded movement information to subsequently correct the activity distribution data. The movement is measured and stored before the activity distribution evaluation is performed, allowing the correction to be applied in the reconstruction phase.
Solution Approach 2:
The patent implements feedback by using the measured movement information to correct the activity distribution data. The system continuously monitors target movement and feeds this information back into the image reconstruction process to compensate for motion effects, thereby maintaining measurement precision despite target movement.
2Measurement precision
If movement correction methods are applied during PET data recording, then the measurement precision of activity distribution is improved, but the device complexity increases due to additional movement detection and correction systems
Solution Approach 1:
The patent applies universality by integrating multiple functions into the existing PET system. The movement detection device can be the same type used for irradiation control, and the correction algorithms utilize the same infrastructure already present in the particle therapy system, thereby reducing the need for entirely separate dedicated systems.
Solution Approach 2:
The patent uses an intermediary approach by introducing a movement detection device that serves as a mediator between the target object and the PET measurement system. This intermediary captures movement information that is then used to correct the activity distribution data, bridging the gap between moving target and stationary detector.
3Reliability
If security margins are applied surrounding the target volume, then the reliability of dose delivery is improved, but the manufacturing precision of dose distribution deteriorates due to over-irradiation of surrounding areas
Solution Approach 1:
The patent replaces the mechanical/geometric approach of security margins with a computational correction approach. Instead of physically expanding the irradiation field to account for movement, the system uses software-based movement correction to maintain precise dose delivery, substituting mechanical tolerance with algorithmic 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, movement-corrected reconstruction of the activity and dose distribution in moving targets, improving the evaluation of the deposited dose and allowing for precise monitoring and verification of irradiation processes.
Implementation Method 1
A PET system detects the photons which are emitted by β+ radioactive nuclides. The β+ radioactive nuclides, in turn, are generated by the interaction of the particle beam with the material or tissue to be irradiated.
Implementation Method 2
The β+ radioactive nuclides, in turn, are generated by the interaction of the particle beam with the material or tissue to be irradiated
Implementation Method 3
loaded particles, for example, protons or carbon ions or ions of other elements are accelerated to high energies, formed into a particle beam and guided via high energy beam transport system to one or several treatment rooms
Data Source
AI summary
The invention relates to an apparatus for evaluating an activity distribution obtained in a moved target object by a beam that is generated by an irradiation device. Said apparatus comprises: a positron emission tomograph designed to record photons generated in the target object by the beam and generate measurement data representing points of origin of the photons; a movement detection device designed to generate a movement signal representing the movement of the target object; and an evaluation unit designed to associate the points of origin of the measured photons with positions in the target object with the help of the movement signal such that three-dimensional characteristics of the activity distribution actually generated in the target object can be evaluated by means of the photons generated by the beam. The invention further relates to an irradiation system and a method in which such an apparatus is used.