Figure 1.

Selection of bony landmarks related to the target volumes in HNC RT. a) Selection of four subregions (white boxes) to measure the combined effect of rotation, mutual movement and shape changes of the bony landmarks. Image matching for these areas was based on well defined structures (indicated in black) in the vertebrae C1-2 and C5-7, the mandible and the occiput bone. b) Example of large and small CTV volumes in tonsilla carcinoma (outer and inner lines) with prescribed doses of 54 and 60 Gy, respectively. The lower dose volumes may extend to all four subregions while the higher dose volumes (receiving 60 Gy or more) typically covers only one or two of the subregions.