Rare but devastating neurological tissue injury by proton therapy is poorly understood. One consideration is that the transition from passively scattered to pencil beam scanning (PBS) proton radiotherapy over the past decade has affected dose rate. We analyzed clinical data acquired at two institutions on a correlation of voxel-wise dose rates and injury of brain tissue (institution 1) and the optic apparatus (institution 2). All radiation-induced toxicities were delineated (Brain/optic apparatus) on follow-up MRIs. A method to calculate dose rates for PBS plans has been implemented at two institutions independently. Institution 1 reports beam-by-beam time-averaged maximum dose rates per voxel (VMDR) using a 100 ms time interval. Data from four patients who incurred brain tissue injury was included. Dose rate volume histograms were prepared for the target, a 1 cm outer ring to the target, and the necrotic region itself. Prescription doses ranged from 30.6 to 60 Gy delivering either 1.8 or 2.0 Gy per fraction. Tissue injury was generally observed in the dose fall-off at the edge of the target. Additionally, we performed LET weighted dose calculation, robustness analysis, and Monte Carlo calculations. Institution 2 presents voxel-wise dose delivered above a selected dose rate threshold, considering values between 30 and 180 Gy/min. The analysis was performed for 2 cases with optical apparatus injuries and one matching non-toxicity case. Both injuries were observed in the chiasma. Patients received 50.4, 50.4 and 55.8 Gy (non-toxicity) in 1.8 Gy fractions. D1 for chiasma was 51.1, 47.2 and 54 Gy, respectively. Mean and (max) LET in chiasma were 4.02 (4.72), 2.49 (3.16) and 3.44 (4.56) keV/µm accordingly. Institution 1 finds distinct dose rate hot spots in the contoured injured brain regions. Mean VMDR values across all beams are lower in targets than in the 1 cm outer ring (80 Gy/min and 82.8 Gy/min, respectively) and elevated to 113 Gy/min for necrotic regions. Neither of the additional computations showed significant increase of dose in the affected areas. Institution 2 observes that chiasmas, which developed radiation injuries, were exposed to higher dose levels delivered at elevated dose rates (> 72 Gy/min) than the chiasma that did not show any radiation injury. D95 above 72 Gy/min for the two volumes identified as radiation injury was 0.25 and 0.12 Gy/fx, while D98 to chiasmas minus radiation injury or chiasma without any injury for the matching case was 0.06, 0.03 and 0 Gy/fx respectively. Using unique formulations to assess voxel-wise dose rates to brain and optic chiasm, two independent institutions observed that regions with elevated dose rates correlated with radiographic radiation injury. An extended retrospective study including a larger patient cohort with radiation-induced toxicity and asymptomatic patients is under way to confirm or refute the presented observations.