3D-Printed SPECT Collimators With Layered Permutation Control
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Solution Overview
Problem
Conventional 3D printing methods fail to produce collimators with the required tolerances and uniformity for medical imaging applications, particularly in SPECT systems, due to limitations in controlling the position and speed of the extruding printhead and the high viscosity of print materials, leading to increased costs and inefficiencies in producing lead-free, RoHS-compliant collimators.
Innovation Solution
Implementing layered-permutation sequence algorithms to specify the content of stereolithography files for 3D printers, allowing for the production of collimators with precise layering and non-repeating permutation sequences that ensure the required thickness and quality, using off-the-shelf components and enabling the creation of collimators with a large field-of-view for medical modalities like SPECT.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional 3D printing methods are used to produce collimators, then production cost is reduced and manufacturing speed is improved, but manufacturing precision and uniformity deteriorate due to high viscosity of print material and inability to control printhead position and speed accurately
Solution Approach 1:
The patent applies preliminary action by pre-heating the print material to a specific temperature range (200-400°C) before extrusion to reduce its viscosity. This preliminary thermal treatment enables the high-viscosity lead-containing material to flow smoothly through the printhead, achieving both rapid additive manufacturing and the precise dimensional tolerances (±0.05mm) required for medical imaging collimators
Solution Approach 2:
The patent changes the thermal parameter of the print material by maintaining it within a specific temperature range (200-400°C) during the extrusion process. This parameter change reduces the material's viscosity and enables precise control of the extrusion rate, resolving the contradiction between manufacturing speed and precision by allowing fast printing while maintaining tight tolerances for collimator septa thickness and positioning
2Reliability
If high-density and high-atomic number materials are embedded in print material to increase radiation attenuation, then collimator performance is improved, but material viscosity increases making 3D printing more difficult
Solution Approach 1:
The patent changes the thermal parameter of the print material by heating it to 200-400°C, which reduces the viscosity of the polymer matrix containing high-density materials like bismuth or lead. This temperature-controlled parameter change enables the embedded high-atomic-number particles to be extruded smoothly without clogging, maintaining both radiation attenuation performance and manufacturability
Solution Approach 2:
The patent uses composite materials consisting of a polymer matrix (e.g., polycarbonate or acrylic) embedded with high-density, high-atomic-number particles (bismuth, lead, or tungsten). This composite structure combines the ease of extrusion of polymers with the superior radiation attenuation of heavy metals, resolving the contradiction between printability and radiation shielding effectiveness
3Object-affected harmful factors
If green manufacturing processes are used to produce Pb-free and RoHS-compliant collimators, then environmental compliance is improved, but production cost increases significantly
Solution Approach 1:
The patent changes the material composition parameter by using aluminum (atomic number 13) instead of lead (atomic number 82) as the high-density filler material. Aluminum oxide or aluminum hydroxide particles provide sufficient radiation attenuation for many SPECT applications while being non-toxic and RoHS-compliant. The additive manufacturing process reduces production cost compared to traditional green manufacturing methods, simultaneously achieving environmental compliance and cost reduction
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 rapid and accurate manufacturing of collimators that meet medical imaging standards, improving image reconstruction and reducing production costs by utilizing commercially available 3D printing components, while allowing for quick prototyping and testing of new designs.
Implementation Method 1
systems and methods implement one or more layered-permutation sequence algorithms that specify the content of a stereolithography file to instruct a 3D printer to produce a collimator using an additive, layered process
Implementation Method 2
The collimator acts as the front-end of a gamma camera, and has a big impact on the signal-to-noise ration of the captured image. The collimator functions to spatially control the propagation direction (i.e., field-of-view) of the gamma rays reaching the detector
Data Source
AI summary
A method of manufacturing a collimator (134) on a three-dimensional printer (510) includes obtaining design specifications (536) for the collimator, the design specifications including a channel perimeter pattern and an overall collimator thickness, determining a first quantity of deposit layer permutation types based on the channel perimeter pattern, determining a respective second quantity of permutation layer elements (310, 320, 330) for each respective one of the deposit layer permutations, generating respective sets of sequences for each respective one of the deposit layer permutations, the number of sets equal to the respective second quantity for the corresponding deposit layer permutations, assembling the respective sets of sequences into a three-dimensional print file (538), providing the three-dimensional file to the three-dimensional printer, and manufacturing the collimator by depositing additive layers of material based on contents of the three-dimensional file. A system for implementing the method and a non-transitory computer-readable medium are also disclosed.