A comprehensive quality assurance protocol for electromagnetic tracking in brachytherapy.

Area of Science:

• Medical Physics
• Radiation Oncology
• Biomedical Engineering

Background:

• Electromagnetic tracking (EMT) systems provide crucial applicator location and geometry data for brachytherapy (BT).
• EMT enhances pre-treatment verification, detecting errors to improve patient safety in radiation oncology.
• Individualized treatment planning benefits from accurate real-time applicator positioning data.

Purpose of the Study:

• To design, develop, and test a measurement protocol for EMT-enabled afterloaders in brachytherapy.
• To collect and compare EMT performance data from three distinct radiation oncology centers.
• To assess EMT accuracy and precision in various clinical environments.

Main Methods:

• A novel quality assurance (QA) phantom was utilized to evaluate EMT sensor precision (jitter) and accuracy (distance errors).
• Measurements were conducted using an afterloader prototype with integrated EMT sensors.
• Testing occurred in diverse settings: laboratory, brachytherapy suite, operating room, CT, and MRI suites.

Main Results:

• Mean positional jitter remained under 0.1 mm, with slight increases at greater distances.
• Variability in tandem and ring applicator positioning was below 0.1 mm.
• Tracking accuracy was highest near the center, with relative distance errors ranging from 0.2-0.3 mm centrally to 5.5 mm at edges. Clinical environments showed comparable accuracy (median 0.1-0.4 mm), except CT suites (median up to 1.0 mm).

Conclusions:

• The developed QA protocol confirms EMT's high accuracy for applicator/implant geometry in brachytherapy, even in clinical settings.
• EMT-enabled afterloaders demonstrate reliable performance across multiple radiation oncology centers.
• EMT integration enhances safety and precision in brachytherapy through accurate geometric verification.