Irradiation of paranasal sinus tumors: Comparison of conformal threedimensional versus conventional treatment planning

PURPOSE: To assess the possibility of delivering a homogeneous irradiation with respect to maximal tolerated dose to the optic pathway for Paranasal sinus tumors. MATERIAL/METHODs: Treatment planning with conformal three-dimensional (3D) and conventional two dimensional (2D) was done on the CT scans of the twenty patients who had early or advanced paranasal tumors. None of the cases were previously irradiated. Two to four individually shaped isocentric noncoplanar field arrangement were designed. Dose-volume histograms (DVH) for the planning target volume (PTV) and the visual pathway including globes, chiasma and optic nerves were compared in two treatment plannings. RESULTS: The area under curve (AUC) in the DVH of the globes in the same side and contralateral side of tumor involvement was significantly higher in 2D planning (P<0.05) which caused higher integral dose to the both globes. Also, the AUC in the DVH of chiasma was higher in 2D treatment planning (P=0.002). The integral dose to the contralateral optic nerve was significantly lower with 3D planning (P=0.007), but there was no significant difference for the optic nerve which was in the same side of tumoral involvement (P>0.05). The AUC in the DVH of PTV was not significant (201.1±16.23 mm3 in 2D planning and 201.15±15.09 mm3 in 3D planning). The volume of PTV which received 90% of the prescribed dose was 96.9±4.41 cc in 2D planning and 97.2±2.61 cc in 3D planning (P>0.05). CONCLUSION: Three dimensional conformal radiotherapy for paranasal sinus tumors enables the delivery of radiation to tumor with respect to critical organs with a lower toxicity to optic pathway.

کلیدواژه ها:

Treatment planning ، Paranasal sinus tumors ، Radiotherapy