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A proposal of an open PET geometry
Taiga Yamaya1, Taku Inaniwa, Shinichi Minohara
1Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555 Japan. taiga@nirs.go.jp
Physics in Medicine and Biology
|January 18, 2008
Summary
This study introduces an open Positron Emission Tomography (PET) scanner geometry to improve patient comfort and enable new applications like in-beam cancer therapy monitoring. The open design, validated with simulations and experimental data, shows promising image quality with reduced artifacts.
Area of Science:
- Medical Imaging Physics
- Nuclear Medicine Technology
- Radiological Engineering
Background:
- Conventional Positron Emission Tomography (PET) scanners have long patient ports causing patient discomfort (claustrophobia) and limiting care during scans.
- Existing PET systems restrict simultaneous imaging with other modalities like Computed Tomography (CT) due to separated fields of view (FOV).
- There is a need for improved PET scanner designs that enhance patient experience and facilitate novel clinical applications.
Purpose of the Study:
- To propose and evaluate a novel 'open PET' scanner geometry featuring two axially separated detector rings.
- To assess the feasibility of 3D image reconstruction for the open PET geometry using iterative methods.
- To explore the potential of the open PET for in-beam Positron Emission Tomography (PET) and simultaneous PET/CT imaging.
Main Methods:
- Implementation of a 'masked' 3D ordered subset expectation maximization (OS-EM) algorithm for image reconstruction.
- Simulation of a dual HR+ scanner with variable gaps to evaluate imaging performance and artifact reduction.
- Experimental validation using a prototype brain scanner (jPET-D4) with simulated open geometry.
Main Results:
- The open PET geometry enables a continuous, 360-degree field-of-view with a 3D image reconstruction capability.
- Artifacts near the open space were effectively reduced by optimizing detector placement, even when the gap exceeded optimal limits.
- Experimental data from the jPET-D4 demonstrated that the open geometry yields comparable images to conventional configurations, despite minor artifacts at gap ends.
Conclusions:
- The proposed open PET geometry is a viable alternative to conventional designs, offering improved patient comfort and flexibility.
- This innovative design facilitates advanced applications such as in-beam PET for real-time monitoring of particle therapy.
- The open PET geometry allows for simultaneous PET/CT imaging within the same field of view, overcoming limitations of current systems.
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