Motoki Matsushima

Photoelastic Stress Analysis Error Quantification in Vasculature Models for Robot Feedback Control

Real-time and accurate stress calculation in walls of vasculature is desired to provide catheter insertion robots of feedback control without changing the catheter stiffness and lumen. This feedback source has also applications in endovascular surgery simulation for human skills and medical tools evaluation. For that purpose we consider photoelastic effect, as birefringence produced by light retardation relates with the stress inside the photoelastic materials. In this research a polariscope was designed for urethane elastomer vasculature models, the photoelastic coefficient of urethane elastomer was measured, and the camera system was calibrated to quantify and reduce error of the measurement system. An average error of 3.6% was found for the pressure range of 70–189 mmHg inside the model of urethane elastomer, this enables to calculate accurately stress in vasculature models during Human Blood Pressure Simulation (HBPS). That way we will be able to compare in a closed loop stress produced by HBPS and by the catheter motion when manipulated by a robot.

Photoelastic stress analysis in blood vessel phantoms: three‐dimensional visualization and saccular aneurysm with bleb

The photoelastic effect is used for stress measurement during endovascular surgery simulation for quantitative evaluation of catheter trajectory in in vitro environments. By extending the capabilities of this sensing technology, its potential for intravascular tools evaluation will increase.

Three-dimensional visualization of photoelastic stress analysis for catheter insertion robot

It is desirable for endovascular surgery simulation to describe with quantitative data the interaction between the catheter and the blood vessel model wall to make an objective evaluation of the procedure. Photoelastic stress analysis in straight segments of multi-layered models was used for that purpose. In this research we study the error introduced by stress direction on the magnitude measurements, for photoelastic stress analysis. And we propose a scanner for three dimensional visualization of photoelastic stress analysis. As result, we quantified that the maximum contribution of error from stress direction in the first half of the fringe is 2.52% for the stress magnitude measurements. Three-dimensional stress visualization was obtained in segment of straight vasculature with an average error in sample slices of 10.73%, 4.55% and 3.18% for inner pressures of 80, 120 and 160mmHg respectively.

Photoelastic stress analysis error quantification in vasculature models for robot feedback control

Real-time and accurate stress calculation in walls of vasculature is a desired goal in order to provide feedback control for catheter insertion robots without changing catheter stiffness and lumen. This feedback source also has applications in endovascular surgery simulation. In order to address this need, we consider photoelastic effect, as birefringence produced by light retardation relates to the stress inside photoelastic materials. In this research, a polariscope was designed for urethane elastomer vasculature models, the photoelastic coefficient of urethane elastomer was measured, and a camera system was calibrated to quantify and reduce error in the measurement system. An average error of 3.9% was found in stress measurements for the pressure range of 60-189 mmHg inside the urethane elastomer model. This result was applied to correct stress distribution images, using the average stress value as a reference and preserving local maxima and minima of stress. This enabled us to accurately calculate stress in vasculature models during human blood pressure simulation (HBPS), and enables the comparison, in a closed loop, of stress produced by HBPS and by catheter motion when driven by a robot, as well as to measure the stress produced by medical tools on the vascular model wall.

Human blood pressure simulation for photoelastic stress analysis in models of vasculature

The development of a numerical criterion to evaluate the stress on models of vasculature has applications in evaluation of human skills, robots and medical tools. This criterion will enable better medical training for endovascular surgery and the development of better medical techniques and tools. We propose to use the stress produced by human blood pressure simulation in the wall of the model of vasculature as this criterion; and to measure the principal component of stress magnitude using photoelastic effect. For that we simulated human blood pressure with a 5.6% of average error, we developed a shielded urethane model of vasculature enabling water circulation and avoiding plastic deformation with pressures below 182 mmHg. We developed software to calculate the stress of the model wall. Stress produced by human blood pressure simulation and a guide wire were compared numerically in four ranges.

PHOTOELASTIC Stress Analysis on Patient-Specific Anatomical Model of Cerebral Artery by Reflection Method

Artery models and surgical simulators are required for safety surgery. We have proposed a novel method to produce biological models using polyurethane elastomer, which has high photoelastic coefficient. And a method is to analyze stress on the model by circular polarized light method. the quantitative stress is analyzed from rainbow-colored photoelastic pattern. But the measurement area is restricted for the fringe area of the artery model. In this paper, we propose stress measurement on biological model by reflection method, which is a stress measurement method using photoelastic effect. With this method, stress is measured in area wider than that of circular polarized light method. For the reflection method, the Reflection layer was coated between first layer of polyurethane elastomer and second layer of it. From SEM image of cross section of this artery model image, we confirmed uniform thickness of acrylic resin and adhesion between polyurethane layer and acrylic layer. To use this reflection model, We could quantify the error of photo elastic stress analysis. the measurement accuracy of stress state of model reflection area was found to be 9.1% about stress magnitude and plusmn 7[deg] about stress directions. And an application on artery model is verified experimentally. Finally, Stress on the vascular wall caused by the contact with a catheter was successfully measured. Consequently, it should be valuable for various applications not only surgical simulations but also hemodynamic studies and pathological studies.