DOSE-VOLUME COMPLICATION ANALYSIS FOR VISUAL PATHWAY STRUCTURES OF PATIENTS WITH ADVANCED PARANASAL SINUS TUMORS

Purpose: The purpose of the present work was to relate dose and volume information to complication data for visual pathway structures in pat ients with advanced paranasal sinus tumors. Methods and Materials: Thr ee-dimensional (3D) dose distributions for chiasm, optic nerve, and re tina were calculated and analyzed for 20 patients with advanced parana sal sinus malignant tumors, 3D treatment planning with beam's eye view capability was used to design beam and block arrangements, striving t o spare the contralateral orbit (to lessen the chance of unilateral bl indness) and frequently the ipsilateral orbit (to help prevent bilater al blindness), Point doses, dose-volume histogram analysis, and normal tissue complication probability (NTCP) calculations were performed, P ublished tolerance doses that indicate significant risk of complicatio ns were used as guidelines for analysis of the 3D dose distributions. Results: Point doses, percent volume exceeding a specified published t olerance dose, and NTCP calculations are given in detail for patients with complications versus patients without complications, Two optic ne rves receiving maximum doses below the published tolerance dose sustai ned damage (mild vision loss), Three patients (of 13) without optic ne rve sparing and/or chiasm sparing had moderate or severe vision loss, Complication data, including individual patient analysis to estimate o verall risk for loss of vision, are given. Conclusion: 3D treatment pl anning techniques were used successfully to provide bilateral sparing of the globe for most patients, It was more difficult to spare the opt ic nerves, especially on the ipsilateral side, when prescription dose exceeded the normal tissue tolerance doses, NTCP calculations may be u seful in assessing complication risk better than point dose tolerance criteria for the chiasm, optic nerve, and retina, It is important to a ssess the overall risk of blindness for the patient in addition to the risk for individual visual pathway structures. (C) 1997 Elsevier Scie nce Inc.