Familial Nasopharyngeal Carcinoma 6

202 L. Kong, J. J. Lu, and N. LeeFig. 16.3. Target volumes and radiation dose distribution of a patient with T2N2M0 NPC. GTV, CTV, and PTC delineatedaccording to the RTOG 0615 protocol.the treatment of NPC, the complex anatomy of the headand neck area usually requires the utilization of asophisticated computerized optimization algorithm forbetter dose distribution. Poon et al. (2007) compareddose–volume histograms of target volumes and organsat risk in 57 patients with NPC using inverse- or forward-plannedIMRT. The results revealed that bothplanning methods provided excellent target coveragewith no statistically significant differences; however, theinverse planning IMRT provided improved sparing to anumber of organs at risk including parotid glands, temporomandibularjoint, brainstem, and spinal cord (Fig.16.5). Furthermore, inverse planning led to a dose reductionto the middle/inner ear in the T1/T2 subgroup.