Optimizing Neurocognition With Whole Brain Radiation Therapy (WBRT) Using Upfront Pulsed Reduced Dose-Rate (PRDR) Technique

"Both extended release memantine and twice daily memantine dosing will be allowed.~Twice daily dosing:~The target dose for memantine is 20 mg (10 mg divided twice daily). Dose will be escalated by 5 mg each week to a target of 10 mg twice daily (i.e., 5 mg a day on week 1, then 5 mg twice daily (BID) on week 2, then 10 mg in AM plus 5 mg in PM on week 3, followed by 10 mg in AM plus 10 mg in PM by week 4).~Extended Release Memantine:~The target dose for extended release memantine is 28 mg. Dose will be escalated by 7 mg per week to a target of 28 mg daily (i.e., 7 mg a day on week 1, then 14 mg a day on week 2, then 21 mg a day on week 3, followed by 28 mg a day by week 4)."

The total dose of 3000 cGy (30 Gy) will be divided 10 fractions of 300 cGy (3 Gy); each fraction will be delivered as a series of 20 cGy (0.2Gy) pulses separated by 3 min time intervals. 20 cGy / 3 min = 6.67 cGy/min (or 0.0667 Gy/min). Total time is determined by the fractionated series and time intervals, meaning 300cGy/20cGy = 15 division x 3 minutes = 45 minutes. Including time to set up, approximate total time per treatment session will be 60 minutes.