Ti-23Ta-3Sn Shape Memory Alloy Marker for Low Invasiveness X-Ray Visibility
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Solution Overview
Problem
Current markers for identifying cancer tissue in the body, such as those made of stainless steel or nickel-titanium alloys, face challenges including high invasiveness, low X-ray absorptivity, and potential issues with MRI diagnostics due to magnetic properties, making accurate and easy identification difficult.
Innovation Solution
A marker composed of a titanium alloy with higher X-ray absorptivity than stainless steel and lower magnetic properties than platinum-tungsten alloys, specifically a Ti-23Ta-3Sn alloy, is used, which is formed into a shape with a predetermined radius of curvature and elastic limit to provide high visibility in X-ray images and compatibility with MRI diagnostics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a stainless steel hook wire is used as a marker, then the marker can be inserted and deployed in the living body, but the degree of invasiveness to the living body is high and the wire diameter cannot be reduced
Solution Approach 1:
The patent changes the material parameter from stainless steel to nickel-titanium alloy, which fundamentally alters the mechanical properties. The nickel-titanium alloy exhibits superelasticity and shape memory effects, allowing the wire to undergo large elastic deformations without plastic deformation. This enables the wire to be straightened for insertion through thin needles and then return to its original curved shape to mark the cancer tissue, thereby reducing the required needle diameter and minimizing invasiveness.
Solution Approach 2:
The patent utilizes the dynamic mechanical behavior of nickel-titanium alloy, specifically its superelasticity and shape memory properties. The wire is designed to dynamically change its shape: straight during insertion through the needle, and then curves back to its original configuration after deployment. This dynamic shape transformation allows the marker to be inserted through a thin needle while maintaining its marking function, effectively reducing the invasiveness without compromising the wire diameter.
2Length of moving object
If a nickel-titanium-based shape memory alloy wire is used, then the wire diameter can be reduced and flexibility increased, but the X-ray absorptivity is low resulting in poor contrast property
Solution Approach 1:
The patent applies local quality by differentiating the material composition between the core and the outer layer of the wire. The core consists of nickel-titanium alloy providing superelasticity and shape memory properties, while the outer layer is coated with a high X-ray absorptivity material such as platinum, gold, or tungsten. This layered structure ensures that the nickel-titanium core maintains the wire's flexibility and deformability, while the outer coating enhances X-ray visibility without significantly increasing the overall wire diameter.
Solution Approach 2:
The patent employs composite material construction by combining nickel-titanium alloy with high X-ray absorptivity materials. The composite structure integrates the advantageous properties of both materials: the nickel-titanium provides elastic deformation capability and shape memory effect, while the outer coating of platinum, gold, or tungsten provides high X-ray absorptivity. This composite approach resolves the contradiction between reducing wire diameter for low invasiveness and enhancing X-ray visibility for accurate detection.
3Length of moving object
If a nickel-titanium-based alloy wire is used, then the wire can be inserted through a thin injection needle, but strong magnetic properties cause artifacts in MRI images and heat generation
Solution Approach 1:
The patent applies local quality by using nickel-titanium alloy with controlled composition and structure to minimize magnetic properties in the core material, while the outer coating provides the necessary radiopacity. By carefully selecting the nickel-titanium ratio and heat treatment conditions, the magnetic susceptibility is reduced to minimize MRI artifacts and heat generation, while maintaining the superelasticity and shape memory properties needed for insertion through thin needles.
Solution Approach 2:
The patent considers using alternative materials or coatings that are non-magnetic or have minimal magnetic properties, such as platinum or gold coatings, which do not interfere with MRI diagnostics. These outer layers serve as both the radiopaque element and a non-magnetic barrier, allowing the marker to be inserted through thin needles while being compatible with MRI imaging without causing significant artifacts or heat generation.
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
The titanium alloy marker allows for accurate and easy identification of cancer tissue with reduced invasiveness and physical burden, enhancing X-ray contrast and minimizing MRI-related artifacts, facilitating both diagnosis and follow-up procedures.
Implementation Method 1
a contrast material for medical use that can reduce a degree of invasiveness to a living body and can accurately identify the position of cancer tissue and the like through the use of a nickel-titanium (Ni—Ti)-based shape memory alloy
Implementation Method 2
the wire is less likely to have plastic deformation while allowing for flexible elastic deformation due to its superelasticity
Implementation Method 3
the indicator part is configured to indicate information on the living body or information on the indicator part by a difference in X-ray image
Data Source
AI summary
A marker for use in a living body includes an indicator part to be placed in a living body for a predetermined period of time, and the indicator part is configured to indicate information on the living body or information on the indicator part by means of a difference in X-ray image. Thus, there are provided the marker for use in a living body and an instrument set for inserting the marker for use in a living body capable of identifying a predetermined site in a living body easily and accurately.