Planning with customized PTV allows decreased dose to critical normal structures. A. A patient with a centrally-located malignant glioma underwent replanning with a CTV to PTV expansion of 1.5 mm as measured by IGRT in the first three days of treatment. This decreased dose to the brainstem (blue, max from 5935 to 5550 cGy and mean from 4153 to 3596 cGy), hippocampus (orange, max from 6052 to 5761 cGy and mean from 3892 to 3006 cGy), and temporal lobe (yellow, max from 6550 to 6311 cGy and mean from 2623 to 2205 cGy). B. Axial representative isodose curves from original and reduced PTV, respectively.