Figure 3. The primary planning target volume (PTV) (in red) is shown encompassed by the 95% (green) isodose curve (63 Gy in 28 fractions). The elective PTV (neck nodes in pink) is treated to a lower dose (78% isodose curve in orange; 51.8 Gy in 28 fractions), whilst the spinal cord is kept below 40 Gy (60% isodose curve in pale blue).