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Scanning E-field sensor device for online measurements in annular phased-array systems
1Department of Radiation Oncology, Charité Medical School, Berlin, Germany.
Summary
This study demonstrates an electro-optical electric field (E-field) sensor for noninvasive monitoring during radiofrequency (RF) hyperthermia. The sensor enables precise control and power distribution estimation, advancing cancer treatment technology.
Area of Science:
- Biomedical Engineering
- Electromagnetics
- Medical Physics
Background:
- Accurate control of antennas and power distribution is crucial for effective regional radiofrequency (RF) hyperthermia.
- Noninvasive measurement techniques are needed for simultaneous monitoring during treatment.
- Technological advancements require precise methods for estimating power deposition in patients.
Purpose of the Study:
- To investigate the feasibility of an electro-optical electric field (E-field) sensor for clinical RF hyperthermia.
- To develop a device for noninvasive, simultaneous antenna control and power distribution estimation.
- To assess the sensor's utility in evaluating antenna design and patient-specific hyperthermia planning.
Main Methods:
- An electro-optical E-field sensor utilizing lithium niobate crystals and a Mach-Zehnder interferometer was employed.
- A mechanical scanning device facilitated E-field registration during clinical application in a water bolus.
- Measurements were compared with finite-difference time-domain (FDTD) modeling, using refined antenna models and phantom studies, including patient treatments.
Main Results:
- FDTD modeling accurately described phantom and patient measurements when antenna models incorporated conical dipole shapes and dielectric environments.
- E-field measurements between antennas and patients are essential for characterizing antenna radiation properties, sensitive to variations in the lossy medium.
- Patient-specific variations in amplitude and phase were moderate, with maximum fluctuations of 40% and 30 degrees, respectively.
Conclusions:
- The electro-optical E-field sensor is a practical tool for online registration of E-field phase and amplitude.
- The method aids in evaluating antenna designs, validating modeling calculations, and understanding multi-antenna systems.
- Clinical application allows for patient-specific hyperthermia planning and online power distribution optimization.