X-ray Fluoroscopy Guided Localization and Steering of Medical Microrobots through Virtual Enhancement (2409.08337v1)

Abstract: In developing medical interventions using untethered milli- and microrobots, ensuring safety and effectiveness relies on robust methods for detection, real-time tracking, and precise localization within the body. However, the inherent non-transparency of the human body poses a significant obstacle, limiting robot detection primarily to specialized imaging systems such as X-ray fluoroscopy, which often lack crucial anatomical details. Consequently, the robot operator (human or machine) would encounter severe challenges in accurately determining the location of the robot and steering its motion. This study explores the feasibility of circumventing this challenge by creating a simulation environment that contains the precise digital replica (virtual twin) of a model microrobot operational workspace. Synchronizing coordinate systems between the virtual and real worlds and continuously integrating microrobot position data from the image stream into the virtual twin allows the microrobot operator to control navigation in the virtual world. We validate this concept by demonstrating the tracking and steering of a mobile magnetic robot in confined phantoms with high temporal resolution (< 100 ms, with an average of ~20 ms) visual feedback. Additionally, our object detection-based localization approach offers the potential to reduce overall patient exposure to X-ray doses during continuous microrobot tracking without compromising tracking accuracy. Ultimately, we address a critical gap in developing image-guided remote interventions with untethered medical microrobots, particularly for near-future applications in animal models and human patients.

• The paper introduces a digital twin method for real-time tracking and navigation of microrobots under X-ray fluoroscopy.
• The paper achieves high temporal resolution (around 20 ms) ensuring precise microrobot localization and improved operator control.
• The paper demonstrates enhanced X-ray visibility and reduced radiation exposure by integrating virtual enhancements with traditional imaging.

X-ray Fluoroscopy Guided Localization and Steering of Medical Microrobots through Virtual Enhancement

The paper by Husnu Halid Alabay, Tuan-Anh Le, and Hakan Ceylan presents a novel approach to enhance the localization and steering of untethered milli- and microrobots under X-ray fluoroscopy using virtual enhancement through digital twin technology. The paper addresses the critical challenge of ensuring accurate detection, real-time tracking, and precise localization of microrobots within the inherently non-transparent human body.

Methodology

The paper's core innovation is the creation of a simulation environment housing a precise digital replica (virtual twin) of the microrobot's operational workspace. By synchronizing the coordinate systems of the real and virtual worlds and continuously integrating microrobot positional data from the image stream, the microrobot operator can navigate it in near real-time in a more informative virtual environment.

The researchers validated this concept by demonstrating the tracking and steering of a mobile magnetic microrobot within a 2D confined phantom filled with fluid using high temporal resolution visual feedback (less than 100 ms, averaging around 20 ms). This fusion of real-time X-ray fluoroscopy and virtual environments aims to improve the navigational accuracy and operator intuitiveness for microrobot interventions.

Results

Key findings from the paper include:

• High Temporal Resolution: The position synchronization between the real microrobot and its virtual twin consistently achieved delays well below 100 ms, typically around 20 ms.
• Enhanced Visibility: The microrobot, constructed from PDMS and NdFeB magnetic particles, exhibited X-ray visibility surpassing clinical standards (e.g., better contrast than 100% Omnipaque® 350), ensuring reliable detection under X-ray fluoroscopy.
• Successful Navigation: Real-time navigation of the microrobot within the virtual twin was demonstrated, overcoming the limitation of poor anatomical details in X-ray imaging. This included complex tasks like steering a magnet bead through a maze with high accuracy.

Practical and Theoretical Implications

Practical Implications:

1. Reduced Radiation Exposure: By focusing on detecting high-contrast microrobots, the method allows for reduced pulse rates during cinefluoroscopy, thereby potentially decreasing patients' and physicians' exposure to X-ray radiation doses.
2. Improved Control: The virtual twin's detailed visualization significantly enhances the operator’s ability to navigate the microrobot, particularly in confined or complex anatomical spaces.

Theoretical Implications:

1. Digital Twin Technology: The use of digital twins in medical interventions could evolve into a dynamic model that reflects real-time changes and predicts future events, offering comprehensive spatial and temporal representations.
2. Cross-disciplinary Applications: While primarily focused on microrobots, the integration of medical imaging and virtual reality can extend to other domains requiring precise remote navigation and control under non-transparent conditions.

Future Developments

The paper outlines several potential future developments:

1. Integration with Other Imaging Modalities: Combining X-ray fluoroscopy data with MRI or CT scan data to create a more comprehensive virtual environment could further enhance the anatomical details available to the operator.
2. Fully Autonomous Interventions: Virtual interfaces may pave the way for autonomous microrobot interventions by integrating various intraoperative sensory data, thus improving situational awareness and decision-making in real-time.
3. Expanded Use of Virtual Reality: Increased use of virtual reality in medical planning, training, and real-time guidance can improve microrobot system safety and efficacy.

Conclusion

This paper presents a significant advancement in the localization and steering of microrobots under X-ray fluoroscopy through the introduction of a virtual enhancement strategy. The real-time synchronization of a microrobot's position with its digital twin demonstrates notable potential to improve the accuracy, safety, and effectiveness of medical interventions. Future research and development focusing on integrating this approach with other imaging modalities and expanding the virtual reality capabilities will likely propel the field toward higher technological readiness levels for innovative clinical applications.