Figure 1

Evolution of radiotherapy planning. Historically, radiation treatment planning was based on bony landmarks as seen using 2-dimensional x-ray films (A). Modern radiotherapy allows for sculpting of radiotherapy dose in three dimensions (axial B; coronal C; sagittal D), with differential doses to high-risk (thick red line) and low-risk (thick blue line) areas, and relative sparing of the normal tissues including parotid glands, spinal cord and brain.