Technical Advances and Pitfalls in Head and Neck Radiotherapy
Figure 1
Comparison of a HRT plan (a) with an IMRT plan (b). Red color wash is the high-risk clinical target volume (CTV 66). Green color wash is the low-risk target volume (CTV 54) for microscopic disease. CTV66 is covered conformally by the red 98% isodose line in the IMRT plan. In the HRT plan conformality is lacking as the 98% isodose line covers not only CTV66 but also CTV54 as well as normal tissue including the mandible and oral mucosa. The magenta isodose line is an undesirable 105% “hot spot” located on the mandible and in the posterior neck in conventional plan. There are no “hot spots” in the IMRT plan.
