Dual-Axis Rotation PET Scanner Eliminates Parallax Error
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Solution Overview
Problem
Current PET systems with two detector modules rotating around a single central axis suffer from spatial resolution degradation in peripheral zones due to parallax error, despite methods to minimize this error, such as DOI determination.
Innovation Solution
A PET system with two axes of rotation, where one axis is fixed and the other is mobile within a circumference, allows pairs of scintillator crystals and photomultipliers to move independently around both axes, maintaining collinearity and eliminating parallax errors by alternate rotation of the axes to cover a cylindrical field of view.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If two detector modules rotate around a single central axis, then the system structure is simple, but spatial resolution degrades in peripheral zones due to parallax error
Solution Approach 1:
The patent introduces a second rotational axis perpendicular to the first, transforming the system from single-axis rotation to dual-axis rotation. This dimensional change allows detector pairs to maintain collinearity with respect to the object being imaged while rotating around both axes, thereby eliminating parallax error in peripheral zones without significantly increasing overall system complexity
Solution Approach 2:
The patent employs dynamic rotation of detector pairs around two perpendicular axes, allowing the system to adaptively maintain optimal detection geometry. The detector pairs rotate around the first axis to cover different angular positions, and simultaneously rotate around the second axis to maintain collinearity, dynamically adjusting the detection configuration to eliminate parallax error across the entire field of view
2Measurement precision
If DOI determination methods are used to minimize parallax error, then spatial resolution improves, but system complexity and cost increase
Solution Approach 1:
The patent extracts and eliminates the root cause of parallax error by using dual-axis rotation to maintain detector collinearity, rather than adding complex DOI determination systems. This removes the need for additional DOI detection hardware and processing complexity, achieving high spatial resolution through geometric configuration instead of complex measurement systems
Solution Approach 2:
Instead of adding complex DOI determination systems to correct for parallax error, the patent inverts the approach by using dual-axis rotation to prevent parallax error from occurring in the first place. The system proactively maintains optimal detection geometry through mechanical configuration rather than reactively correcting errors through complex electronic systems
3Area of stationary object
If a complete ring of detectors is used, then field of view coverage is complete, but the number of detectors and system complexity increase
Solution Approach 1:
The patent combines the rotational movements around two perpendicular axes to achieve complete field of view coverage equivalent to a complete ring of detectors. By merging the angular coverage from rotation around the first axis with the collinearity maintenance from rotation around the second axis, the system achieves comprehensive coverage using only two detector pairs instead of a full ring
Solution Approach 2:
The patent uses dynamic rotation around two axes to achieve complete field of view coverage with minimal detectors. The detector pairs rotate around the first axis to sweep through different angular positions, and simultaneously rotate around the second axis to maintain optimal detection geometry, dynamically covering the entire cylindrical field of view with only two detector pairs
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 configuration reduces the number of detectors required and eliminates the need for DOI determination, enhancing spatial resolution and image accuracy across the entire field of view.
Implementation Method 1
each detector constituted by a scintillator crystal optically coupled to a photomultiplier
Implementation Method 2
each detector constituted by a scintillator crystal optically coupled to a photomultiplier
Data Source
AI summary
System of positron emission tomography to obtain images of a subject, which comprehends: one first fixed axis of rotation; one second axis of rotation substantially parallel to the first axis, in which the second axis is rotatable around the first axis at a predefined distance; one element of support rotatably coupled to the second axis; one pair of scintillators fixed to the element of support, said pair being collinear and aligned along the same longitudinal axis; two photomultipliers, each optically coupled to one of the scintillators; in which the element of support has a free region between the pair of scintillators to receive the subject to be imaged.