PET Detector Time Calibration via Segmented Radiation Source
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Solution Overview
Problem
Current positron emission computed tomography (PET) systems face challenges in calibrating the time information of all detector modules with high precision, as existing calibration methods are limited to straight-line configurations, making it difficult to adjust the detection time of all modules effectively.
Innovation Solution
The proposed solution involves installing a point radiation source near multiple predetermined detector modules within the PET apparatus, allowing for the calibration of time information across various detector module combinations, including those not on a straight line, by using a calibrator that adjusts the installation positions of the point radiation source to cover a broader range of detector modules.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a point radiation source is installed within the field of view for calibration, then the annihilation gamma rays can be detected by detector modules, but the combination of detector modules is limited to straight lines passing through the point radiation source, making it difficult to calibrate all detector modules
Solution Approach 1:
The field of view is divided into multiple calibration regions, each with its own point radiation source. By segmenting the calibration space and placing multiple radiation sources at different positions, the system can calibrate detector modules across the entire ring-shaped detector array, not just those on straight lines through a single source.
Solution Approach 2:
Multiple point radiation sources are introduced as intermediaries to enable calibration of different detector module combinations. Each radiation source serves as a mediator that allows specific pairs of detector modules to be calibrated, and by using multiple sources, all detector modules can be covered.
2Ease of operation
If the detector modules are arranged in a ring shape around the subject, then functional diagnosis can be performed, but calibrating time information for all detector modules becomes difficult with traditional straight-line calibration methods
Solution Approach 1:
The ring-shaped detector array is divided into multiple calibration zones, each accessible from a different point radiation source position. This segmentation allows systematic calibration of all detector modules by treating each zone separately with appropriate radiation sources placed at optimal positions.
Solution Approach 2:
The calibration approach transitions from one-dimensional straight-line calibration to multi-dimensional calibration by placing point radiation sources at multiple positions around the ring-shaped detector array. This dimensional expansion enables coverage of all detector modules through various calibration geometries.
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 enables the precise calibration of time information for all detector modules, enhancing the accuracy of time-of-flight PET imaging by increasing the number of detectable combinations and improving the precision of detection time differences, thereby improving image reconstruction quality.
Implementation Method 1
a detector configured to calibrate time information of all of the plurality of detector modules by calibrating time information for determining a detection time of a pair of detector modules based on each detection time of the pair of the detector modules which approximately coincidentally count annihilation gamma rays
Implementation Method 2
a point radiation source including a positron emitting nuclide is installed in each position near a plurality of predetermined detector modules
Implementation Method 3
the annihilation gamma rays generated from the point radiation source are detected by a pair of detector modules
Data Source
AI summary
According to one embodiment, a nuclear medicine imaging apparatus includes a detector, a calibrator, and an image reconstruction unit. The detector includes a plurality of detector modules, each counting light originating from a gamma ray. The calibrator unit calibrates time information of all of the plurality of detector modules by calibrating time information for determining each detection time of a pair of detector modules based on each detection time of the pair of the detector modules which approximately coincidentally count annihilation gamma rays and a distance between the pair of detector modules in a state in which a point radiation source including a positron emitting nuclide is installed in each position near a plurality of predetermined detector modules. The image reconstruction unit reconstructs a nuclear medicine image using a time difference between detection times of annihilation gamma rays corrected based on time information calibrated by the calibrator.