Compound Rotational Interface for TRUS Stepper Assembly
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Solution Overview
Problem
Current stabilizer and stepper assemblies for Transrectal Ultrasound (TRUS) imaging and biopsy of the prostate face challenges in navigating the anal and rectal anatomy, particularly in accessing the medial to apical portion of the prostate, and are complicated by anatomical abnormalities and patient movement, limiting their effectiveness.
Innovation Solution
A stabilizer and stepper assembly featuring a compound rotational interface with a compound pinned parallelogram in a scissor arm arrangement, providing six degrees of freedom, including linear and rotational motions, which allows for coarse adjustments without unlocking the stabilizer, enabling access to multiple desired positions and maintaining alignment with the anal sphincter, even during unintended patient movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional stabilizer and stepper assembly is used for TRUS imaging and biopsy, then the basic function of holding and positioning the medical instrument is achieved, but the ability to navigate the anal and rectal anatomy to access the medial to apical portion of the prostate is insufficient
Solution Approach 1:
The interface is segmented into multiple independent rotational joints (first rotational joint, second rotational joint) rather than a single complex joint. Each joint provides a specific degree of freedom, allowing the system to achieve complex navigation paths through composition of simpler rotational movements. This segmentation enables the medical instrument to access the medial to apical portion of the prostate by combining rotations at different joints.
Solution Approach 2:
The interface transitions from a fixed, rigid connection to a dynamic, multi-jointed structure that can adapt its configuration. The rotational joints allow the interface to dynamically adjust its orientation and position, enabling it to navigate the varying anatomical paths presented by the anal and rectal anatomy. This dynamic adaptability is achieved through actuated rotational joints that can change their angular positions in response to anatomical constraints.
2Reliability
If the stabilizer is locked to maintain position, then stability is improved, but the ability to make coarse adjustments without unlocking is limited
Solution Approach 1:
The adjustment functionality is segmented between the stabilizer (fine adjustments when locked) and the interface (coarse adjustments through rotational joints). By placing the coarse adjustment capability in the interface with its rotational joints, the stabilizer can remain locked for stability while the interface independently provides the necessary coarse repositioning. This segmentation of adjustment functions resolves the contradiction between stability and ease of coarse adjustment.
Solution Approach 2:
The interface acts as an intermediary between the stabilizer and the medical instrument. It absorbs the coarse adjustment requirements through its rotational joints, allowing the stabilizer to maintain its locked, stable state while still enabling repositioning. The interface mediates between the need for stabilizer stability and the need for operational flexibility.
3Adaptability or versatility
If the interface supports omni-directional motion, then versatility is improved, but the complexity of the interface structure increases
Solution Approach 1:
Instead of implementing a single complex omni-directional joint, the interface segments the motion into multiple rotational joints, each providing a specific rotational degree of freedom. This segmentation achieves the versatility of omni-directional capability through composition of simpler rotational movements, reducing the complexity of each individual joint while maintaining overall versatility.
Solution Approach 2:
The interface achieves omni-directional capability by adding rotational dimensions through multiple joints rather than relying on a single complex mechanism. Each rotational joint adds a dimensional degree of freedom, and the combination of these dimensional rotations provides the equivalent of omni-directional motion with simpler, more manageable joint structures.
4Ease of operation
If the transducer and needle guide are aligned with the basal to medial portion of the prostate, then anatomical navigation is simplified, but access to the medial to apical portion of the prostate is blocked
Solution Approach 1:
The interface dynamically adjusts its orientation through actuated rotational joints to change the alignment of the transducer and needle guide. Rather than being fixed in a single alignment, the system can dynamically reorient to access different prostate portions. The rotational joints enable the interface to transition from the simplified basal to medial alignment to configurations that access the medial to apical portion.
Solution Approach 2:
The system changes the orientation parameters (angular positions) of the rotational joints to alter the alignment of the medical instrument. By adjusting the angular parameters of the interface joints, the system can change from an alignment suitable for basal to medial access to an alignment that enables medial to apical access, thereby adapting to different anatomical requirements.
Data Source
Figure 1A~1C
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AI summary
Described herein is a compound rotational interface and stepper assembly, the assembly comprising: a stepper supporting linear, rotational or both linear and rotational motion on a longitudinal axis; a compound rotational interface comprising a compound pinned parallelogram in a scissor arm arrangement bound by a first end coupled to a base and a second end coupled to a first rotational joint, the first rotational joint coupled to the stepper; the compound pinned parallelogram moveable from a first linear position to a second linear position and the first rotational joint moveable from a first angular position to a second angular position; and a linear direction defined by the compound pinned parallelogram substantially perpendicular to an axis of rotation defined by the first rotational joint.