Primary tumor volume delineation in head and neck cancer: missing the tip of the iceberg?

Radiation Oncology

Table 2 target volume objectives for dose coverage

Objective^b	Per Protocol	Variation Acceptable	Deviation Unacceptable
D_95% of PTV70	70 Gy (100%)	≤+/-2%	>+/-2%
D_5% of PTV70	≤74.9 Gy (107%)	≤77 Gy (110%)	>77 Gy (110%)
D_98% of PTV70	≥66.5 Gy (95%)	≥63 Gy (90%)^a	<63 Gy (90%)^a
Maximum dose (hot spot ≤0.03 cm³) outside the PTV70	≤74.9 Gy (107%)	≤77 Gy (110%)	>77 Gy (110%)

^aIt is recognized that portions of the PTV close to the skin may receive significantly less than 90% of the prescribed dose. This is acceptable as long as cold spots within PTV do not exist at a depth deeper than 5 mm beneath the skin
^bCTV_S and CTV_L used instead of PTV70 for the purpose of this study

ISSN: 1748-717X