Open Bore Coil System for Electronic FFL Steering in Magnetic Particle Imaging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current Magnetic Particle Imaging (MPI) systems are limited by closed bore scanners with small Field of View (FOV) sizes, making them unsuitable for clinical applications, and lack the ability for electronic steering and rotation of the Field Free Line (FFL), which is essential for efficient and accessible 3D imaging.
Innovation Solution
An open bore coil system is developed, utilizing two parallel coil pairs fed with alternating current directions to generate, rotate, and translate the FFL, allowing for electronic steering and rotation of the FFL within the plane perpendicular to the coil axes, enabling access to the patient during imaging and increasing the FOV while maintaining safety limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If closed bore scanners are used for MPI imaging, then imaging sensitivity is improved, but patient accessibility and field of view are reduced
Solution Approach 1:
The patent inverts the traditional closed-bore scanner design by using an open-bore configuration where the patient lies on a table that can be inserted into or removed from the imaging system. The coil system is arranged to generate the FFL above the patient rather than requiring the patient to be inside a enclosed bore, thereby maintaining imaging sensitivity while improving accessibility.
Solution Approach 2:
The patent transitions from a two-dimensional imaging plane to three-dimensional electronic steering and rotation of the FFL within a large volume. By using multiple coils arranged in specific geometries and controlling their currents independently, the system can electronically position and orient the FFL anywhere within a 3D space above the patient, expanding the effective field of view without requiring physical movement of the patient or coils.
2Volume of moving object
If mechanical rotation of the object is used for FFL scanning, then 3D imaging coverage is improved, but imaging time and complexity increase
Solution Approach 1:
The patent replaces mechanical rotation of the patient or coils with electronic steering of the FFL by independently controlling the currents in multiple coils. The coil system includes at least four coils arranged in a specific geometry, and by adjusting the amplitude and phase of the currents in each coil, the FFL can be electronically positioned and oriented anywhere within the imaging volume without any mechanical movement.
Solution Approach 2:
The patent implements dynamic electronic control of the FFL position and orientation through real-time adjustment of coil currents. The system can rapidly reposition and reorient the FFL in three dimensions by changing the current parameters, enabling fast 3D imaging coverage without the time-consuming mechanical rotation required by traditional systems.
3Area of stationary object
If high amplitude drive fields are applied to expand field of view, then safety limits are exceeded, but if low amplitude fields are used, then field of view remains limited
Solution Approach 1:
The patent divides the drive field generation into multiple independent coils rather than using a single high-amplitude field source. Each coil contributes to the overall FFL generation and imaging process, allowing the total field to be distributed across multiple lower-amplitude sources that individually operate within safety limits while collectively providing sufficient coverage.
Solution Approach 2:
The patent designs the coil system to perform multiple functions: the same coils that generate the FFL are also used to generate the drive field for particle excitation and the gradient field for spatial encoding. This multi-functionality eliminates the need for separate high-amplitude drive field coils, allowing the system to expand the field of view using the existing coil infrastructure operating within safe amplitude limits.
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 system enables high-sensitivity, rapid 3D imaging with a large FOV, allowing for clinical use of MPI by providing electronic control over the FFL, reducing imaging time, and ensuring safety by keeping magnetic field levels below harmful thresholds.
Implementation Method 1
two parallel coil pairs fed with alternating current directions to generate, rotate, and translate the FFL
Implementation Method 2
Change in magnetization vector inside the FFR induces a voltage on the receive coil(s)
Implementation Method 3
Because of the super paramagnetic properties of the nanoparticles, their magnetization can be saturated at moderate magnetic field intensity levels
Data Source
Figure 1~3b
Figure 4~5l
Figure 6a~8
AI summary
An open bore coil system enabling electronic steering and rotation of a Field Free Line (FFL) inside a large volume. An FFL is generated by placing two parallel coil pairs (fed with alternating current directions) side by side. Using two of these coil groups, the FFL can be rotated in the plane perpendicular to the coil axes. The FFL can be translated in the rotation plane of the FFL using a coil pair placed on the same axis with the other coils. It can also be translated in the perpendicular plane by asymmetrical coil excitation. As all the coils in the system are parallel, the imaged object can be reached from the sides during imaging.