PET/CT Partial Scan Reconstruction for ROI-Limited Imaging
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Solution Overview
Problem
Existing PET/CT systems expose patients to high doses of radiation during long axial field of view scans due to the need for extensive CT datasets, which is undesirable despite the requirement for detailed data coverage of the area of interest.
Innovation Solution
Perform a partial scan and reconstruction by limiting data collection and reconstruction to the region of interest using techniques such as disabling detectors outside the area, restricting coincidence events, and applying virtual histogramming or reconstruction to the area of interest.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a long axial field of view CT scan is performed to match the PET aFoV for attenuation and scatter correction, then the coverage of the area of interest is improved, but the patient radiation dose increases significantly
Solution Approach 1:
The patent divides the CT scanning process into two distinct phases: a limited scan that covers only the region of interest (ROI) and a subsequent reconstruction phase that applies attenuation correction using PET data. This segmentation allows the CT scan to be restricted to the necessary anatomical region rather than scanning the entire PET field of view, thereby reducing patient radiation exposure while maintaining sufficient data for accurate attenuation correction.
Solution Approach 2:
The patent applies partial action by performing a CT scan that covers only the partial region of interest rather than the complete axial field of view. The scan is deliberately limited to the necessary anatomical boundaries, and the reconstruction algorithm compensates for the limited coverage by utilizing PET attenuation maps, thus avoiding unnecessary radiation exposure to areas outside the ROI.
2Object-affected harmful factors
If the CT scan is limited to the region of interest, then the patient radiation dose is reduced, but the coverage area for attenuation correction may be insufficient
Solution Approach 1:
The patent introduces PET attenuation maps as an intermediary solution that bridges the gap between the limited CT coverage and the requirement for accurate attenuation correction. The PET scan provides whole-body attenuation information that compensates for the restricted CT scan range, allowing the system to achieve comprehensive attenuation correction without requiring a full axial field of view CT scan.
Solution Approach 2:
The patent changes the parameter of CT scan coverage from full axial field of view to region-of-interest only. This parameter change is compensated by adjusting the reconstruction methodology to incorporate PET-derived attenuation maps, thereby maintaining correction accuracy while reducing scan coverage and radiation dose.
3Productivity
If data collection is limited to the region of interest, then data storage needs and processing time are reduced, but the completeness of the dataset for reconstruction may be compromised
Solution Approach 1:
The patent extracts and utilizes only the necessary subset of data for reconstruction purposes. By identifying and isolating the region of interest, the system extracts only the relevant PET and CT data needed for accurate image reconstruction, discarding unnecessary data from areas outside the ROI. This extraction approach maintains reconstruction quality while minimizing data storage and processing requirements.
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
Minimizes patient radiation dose, reduces data storage needs, and enhances data processing efficiency by focusing on the required area of interest, thus providing effective imaging with reduced radiation exposure.
Implementation Method 1
The interaction of the gamma photons with a scintillation crystal of the detector produces a flash of light
Implementation Method 2
The interaction of the gamma photons with a scintillation crystal of the detector produces a flash of light
Implementation Method 3
PET is based on coincidence detection of two gamma photons produced from positron-electron annihilation
Implementation Method 4
Annihilation events are typically identified by a time coincidence in the detection of the two gamma photons
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
A method for performing a partial scan of a patient using a PET/CT system includes receiving a selection of a region of interest for scanning and performing a CT scan over a region of interest with the PET/CT system to acquire raw CT data. The raw CT data is reconstructed into one or more CT images. The PET/CT system is configured to limit data collection to the region of interest. A PET scan limited to a region of interest is performed with the PET/CT system to acquire raw PET data. The raw PET data is reconstructed into one or more PET images of the region of interest.