Clinical Implementation of Weak Magnetic Field Generator in Radiation Therapy

Abstract

The application of weak magnetic fields may improve radiation therapy efficacy by manipulating the free radical activity induced by radiation to optimize tumor death. Once the device is commercially available, we will conduct clinical trials to determine the clinical impact of the weak magnetic field. However, the magnetic field generator (MFG) restricts Linac gantry rotation to approximately 180° and this limitation may limit treatment plan quality. This work is a continuation of an ongoing study to determine if the gantry angle restrictions can be compensated for during treatment planning. Previous work has demonstrated the feasibility for GBM cases. For this work, 10 prostate cancer treatment plans were retrospectively replanned using only coplanar arcs that spanned from 90° to 270° (half-arcs). The prescriptions were 60 Gy for 6 patients, 55.8 Gy for 2 patients, 54 Gy for 1 patient, and 40.05 Gy for 1 patient. The prescription doses were delivered to 95% of the planning target volume (PTV = GTV + 2 cm). The critical structure doses were compared to determine if clinically equivalent plans could be delivered using half-arcs. The dose criteria that were met by the clinical plans were also met by the half-arc plans except for the cases shown in Table 1. Table 1: Doses that did not meet criteria CONCLUSION: The half-arc plans were able to deliver clinically equivalent dose distributions as the clinical treatment plans. This provides continuing evidence that clinical trials will be able to be developed to evaluate the use of weak magnetic fields for radiation therapy.