Theoretical foundation for real-time prostate localization using an inductively coupled transmitter and a...

Area of Science:

• Medical Physics
• Biomedical Engineering
• Radiotherapy Technology

Background:

• Accurate real-time prostate localization is crucial for effective intensity-modulated radiotherapy (IMRT).
• Current localization methods face challenges in precision and real-time feedback.
• Minimally invasive implantable transmitters offer a potential solution for enhanced tracking.

Purpose of the Study:

• To develop and theoretically validate a system for real-time, 3D prostate localization using implantable radio frequency transmitters and SQUID magnetometers.
• To identify and analyze the key physical parameters influencing system performance for radiotherapy applications.
• To determine the optimal operating mode for achieving precise localization within critical timeframes.

Main Methods:

• Design of a system utilizing an external dipole antenna for charging an on-chip capacitor in a microchip implant transmitter.
• Employing superconducting quantum interference device (SQUID) magnetometers for detecting the magnetic field generated by the implant's discharge current.
• Analysis of system parameters including operating frequency, inductance, capacitance, antenna characteristics, detector distance, and mutual inductance.
• Evaluation of different charge/discharge sequences (half duplex, full duplex, sequential) for optimizing localization accuracy and speed.

Main Results:

• The proposed system enables real-time, 3D localization of the prostate via inductive coupling and magnetic field detection.
• System performance is critically dependent on signal strength, detector sensitivity, and implant capacitor charge time.
• The sequential operating mode demonstrates superior performance for real-time localization, achieving positioning within 1 second.
• Theoretical feasibility and physical limitations of the system for clinical application were established.

Conclusions:

• A passively charged, implantable RF transmitter and SQUID magnetometer system offers a viable approach for real-time prostate localization in IMRT.
• Optimization of physical parameters and selection of the sequential operating mode are essential for achieving the required accuracy and speed.
• This technology holds promise for enhancing radiotherapy precision and patient outcomes by enabling accurate, real-time tumor tracking.