Treatment planning system evaluation for mesothelioma IMRT

Background and purpose: Malignant pleural mesothelioma (MPM) has been treated with extrapleural pneumonectomy (EPP) followed by IMRT. IMRT improved radiation dose distributions to the complex operative bed, and preliminary results suggested improved local control compared with conventional treatment planning. IMRT was initially developed on the Corvus treatment planning system. Other treatment planning systems are also IMRT-capable. Treatment plans from several systems were compared to determine the feasibility of using IMRT in a multi-institution trial. Patients and methods: Treatment plans were generated on Corvus, Eclipse, and Pinnacle for a right-sided MPM after EPP using 6 MV X-rays. Tissue heterogeneity corrections were used in dose calculation. Plans were optimized such that the clinical target volume received 50 Gy in 25 fractions. Dose distributions to the target and normal structures were evaluated. The treatment time and delivery efficiency were estimated. Results: Treatment plans could be calculated by all three planning systems without system failure. Larger volumes received 60 Gy in Corvus plans (40%, 17% and 8% for Corvus, Pinnacle and Eclipse, respectively). Corvus used the most monitor units (2786 versus 1451 and 1813 for Pinnacle and Eclipse), and treated the most segments (1050 versus 267 and 173 for Pinnacle and Eclipse). Doses to spinal cord, lung, heart, liver, and contralateral kidney were acceptable for all planning systems. Conclusions: IMRT plans can be calculated for MPM targets by at least three commonly available treatment planning systems. Pinnacle- and Eclipse-based plans seem more efficient, and may be delivered in a shorter time than Corvus-based plans.