HIFU Transducer Positioning Mechanism for MRI Compatibility
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Solution Overview
Problem
The challenge in high intensity focused ultrasound systems is to develop a positioning mechanism for transducers that is compact, non-magnetic, and compatible with ultrasound conducting mediums, while minimizing radio frequency noise and accommodating limited space within magnetic resonance imaging systems, which existing solutions fail to address effectively.
Innovation Solution
A positioning mechanism comprising a positioning plate with ball joints and linear drives, where rods form ball joints with both the plate and drive blocks, allowing for precise control and compact design with reduced sliding parts, and utilizing materials like ceramic and titanium to withstand liquid environments and large magnetic fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a larger mechanism is used for positioning the transducer, then the positioning precision and stability are improved, but the bore size requirement increases and the cost increases
Solution Approach 1:
The positioning mechanism is divided into multiple rigid rods connected by ball joints, with each rod actuated by an independent linear drive. This segmentation allows the system to achieve precise positioning through coordinated movement of multiple components rather than requiring a single large mechanism, thereby reducing the bore size requirement while maintaining positioning precision.
Solution Approach 2:
The patent replaces traditional mechanical positioning systems with a hybrid system using linear drives (electromagnetic or piezoelectric actuators) to move rigid rods. This substitution eliminates the need for large mechanical linkages and reduces the overall mechanism size, allowing precise positioning within a smaller bore while maintaining accuracy.
2Volume of stationary object
If the mechanism is made more compact to reduce bore size, then the cost is reduced, but the positioning precision and control accuracy deteriorate
Solution Approach 1:
The positioning mechanism uses dynamic coordination of multiple linear drives acting on rigid rods with ball joints. The system achieves compact size by using multiple small actuators working in concert rather than one large actuator, while the dynamic control of rod positions through ball joint rotations maintains high positioning precision despite the reduced overall size.
Solution Approach 2:
The patent employs rigid rods made of non-magnetic, ultrasound-conductive materials (such as ceramic or specialized metals) that are both compact and precisely controllable. These composite or specialized materials allow the mechanism to achieve high stiffness and precision in a compact form factor, maintaining positioning accuracy despite the reduced bore size.
3Ease of operation
If traditional motors and sensors are used in the positioning mechanism, then the functionality is complete, but radio frequency noise is generated
Solution Approach 1:
The patent replaces traditional electromagnetic motors and sensors with alternative actuation mechanisms such as piezoelectric actuators, shape memory alloys, or magnetic field-based actuators that do not generate radio frequency noise. These substitutions maintain the necessary positioning functionality while eliminating the harmful RF noise that would interfere with magnetic resonance imaging operations.
Solution Approach 2:
The positioning mechanism is designed to operate in an RF-shielded or RF-isolated environment, effectively creating an inert electromagnetic field environment around the mechanical components. This allows traditional motors and sensors to function while their RF noise is blocked from interfering with the MRI signals, maintaining functionality without the harmful electromagnetic interference.
4Measurement precision
If the mechanism uses more sliding parts to achieve precise movement, then the positioning accuracy is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent replaces sliding parts with ball joints (spherical connections) to achieve precise positioning. The ball joints allow rotational movement in multiple directions while maintaining a compact, low-complexity structure. This spheroidality approach eliminates the need for multiple sliding surfaces and complex guidance mechanisms, achieving high positioning accuracy through the geometric precision of spherical connections rather than through numerous sliding components.
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 solution enables a compact, precise, and cost-effective positioning mechanism for high intensity focused ultrasound transducers within magnetic resonance imaging systems, reducing the need for larger magnets and minimizing radio frequency noise, thus optimizing the use of space and improving treatment precision.
Implementation Method 1
A positioning mechanism comprising a positioning plate with ball joints and linear drives, where rods form ball joints with both the plate and drive blocks
Implementation Method 2
all the parts may be non magnetic materials and may be able to tolerate the ultrasound conducting medium
Implementation Method 3
The mechanism further comprises a plurality of linear drives. The plurality of linear drives is mounted to the mechanism support
Data Source
AI summary
A high intensity focused ultrasound positioning mechanism (100, 200, 310) for positioning a high intensity focused ultrasound transducer (292, 304), the mechanism comprising: —a positioning plate (108, 308) adapted for receiving the high intensity focused ultrasound transducer; —a mechanism support (174) adapted for mounting the positioning mechanism; —a plurality of rods (110, 112, 114, 116, 118, 120, 210, 212, 214, 216, 218, 220), wherein each rod has a first end and an second end, wherein the first end of each rod forms a separate ball joint (122, 124, 126, 128, 130, 132, 222, 224, 226, 228, 230, 232) with the positioning plate; and —a plurality of linear drives (146, 148, 150, 246, 248, 250, 252, 254), wherein the plurality of linear drives are mounted to the mechanism support, wherein each of the linear drives comprises a drive block (164, 166, 168, 264, 266, 268, 270, 272), wherein the second end of each of the plurality of rods forms a separate ball joint (134, 136, 138, 140, 142, 144, 234, 236, 238, 240, 242, 244) with one of the drive blocks.