Contrast Of Conventional Radiatherapy And IMRT Plan In Single Side PSPS Invaded NPC Staged T_3-4N₀M₀, Ⅲ-Ⅳ

Objective:To make a guideline for radiatiotherapy of single side post styloid prosess parapharyngeal space(PSPS)invaded NPC in stage T_3-4N₀M₀,â…¢-â…£a with 92'Fuzhou Staging System,the different dose distribution of PTV and OAR were studied by comparing conventional radiatiotherapy plan with IMRT plan.Methods:After CT and MRI scanning of 5 PSPS invaded NPC patients,the image were restituted and syncretized in Eclipse External Beam Planning System,after that,we made the conventional radiatiotherapy plan and IMRT one for each patient to evaluate dose distribution according as ICRU 50 and 62 report.Results:1.PGTVD₅,PTV1D₀₅in convention plan is higher than IMRT, PGTVD₉₅,PTV1D₉₅,PTV1Mean,PTV2D₀₅,PTV2D₉₅,PTV2Mean in convention plan are lower than IMRT.2.Spinal cord D₁,optic chiasmaD₁,both sides of temporal lobe D₀₅, parotid D₅₀,optic nervesD₁,temporomandibular joints D₅₀are lower in IMRT plan;lens D₀ are higher in IMRT plan.3.Body Dmean is higher in IMRT plan.Conclusion:To single side PSPS invaded NPC in stage T_3-4N₀M₀,â…¢-â…£a: 1.Dose distribution in IMRT plan is better than the convention one.2.Dose distribution of spinal cord,optic chiasma,both sides of temporal lobe,parotids,optic nerves,temporomandibular joints and are better in IMRT pian。3.Volume of irradiated normal tussue is larger in IMRT plan.