SU-F-T-438: A Practical Technique to Avoid the Radioactive Otitis Media in Whole Brain Radiotherapy.

PURPOSE: Radioactive otitis media is a common complication in whole brain radiotherapy. In this study, we present a practical technique to avoid the injury for whole brain radiotherapy patients.

METHODS: For this study, 10 whole brain radiotherapy patients with planning CT were selected. For the target, 40Gy/20fractions was prescribed. In the treatment planning, two opposing lateral fields were used, from the left and right side of the patient. The MLC (0.5cm width) was used to shape the fields around the brain with a 10 mm margin to allow for the beam penumbra. For 5 patients, six leafs were positioned to block the auris media. For other patients, there were no leafs blocked to auris media according to the routine technique. The target coverage and the mean dose of the auris media were evaluated to assess the new technique in avoiding the radioactive otitis media.

RESULTS: The target coverage of new technique decreased by 1.7% (97.6%±1.1% vs. 99.3%±0.5%) compared routine technique. The mean dose of left auris media decreased by 79% (7.92 Gy±0.81Gy vs. 37.82 Gy±2.33Gy). The mean dose of right auris media decreased by 77% (8.8 Gy±0.93Gy vs. 38.4 Gy±2.65Gy). There was no difference for other OARs.

CONCLUSION: An excellent sparing of the auris media is achievable while maintaining high coverage to the target volume. The simple technique to deliver whole brain may avoid the radioactive otitis media prospectively.