A Case of MRI Induced Thermal Injury during HDR Prostate Brachytherapy: Physics Considerations, and Safety Lessons
Abstract
Purpose
A recent case is presented to highlight that the MR-conditional hover-based Zephyr system which allows smooth patient transfer while preserving needles/applicators can pose sever thermal injury during MRI scanning on a 1.5 Tesla scanner and requires safety measures.
Methods
At our institution, the Zephyr HDR system is used for HDR brachytherapy procedures to facilitate smooth patient transfers while maintaining precise positioning. This ensures accurate and consistent placement of needles and applicators across CT imaging on a Biograph PET/CT, MRI imaging on a Toshiba 1.5 Tesla scanner, and during treatment delivery. MR scanning protocol for HDR brachytherapy at our center includes T2 mVOX (T2-weighted-multi-voxel-acquisition), FE 3D SSFP (Field-Echo-3D-Steady-State-Free-Precession), and T2 FSE 2D (T2-weighted-fast-spin-echo-2D-acquisition). The MR scan typically takes about 30 minutes patient in lithotomy position on Zephyr system.
Results
Over 100 patients with prostate and cervical cancers have undergone HDR brachytherapy at our institution, involving both CT and MRI imaging. Following one procedure, a patient was found to have severe skin burns on the right lateral thigh, which had been in contact with metallic stirrups during MRI on the Toshiba 1.5 Tesla scanner. The patient did not experience pain due to being under anesthesia. This incident was promptly reported to the hospital’s risk management team, the vendor, and the FDA.
Conclusion
Although Zephyr ensures steady needle positioning and precise HDR treatment delivery, there remains risk of MRI-induced thermal injury. This highlights the need for design modifications to further enhance patient safety while ensuring precise treatment delivery. In the interim, we have implemented institutional policies and safety protocols to prevent patient body parts from coming into direct contact with conductive or metallic components, such as stirrups, during MR imaging. These measures are intended to minimize the risk of thermal burns while maintaining the integrity and accuracy of the HDR treatment workflow.