Extended Pleurectomy/Decortication or Surgical Biopsy in the Era of High Doses of Radiation Therapy for Malignant Pleural Mesothelioma

decrease of ITV V90, and 8.3% decrease of PTV V90. There were differences in dose-volumetric parameters of CTV, ITVand PTV between the simulation CT and 4D-CT. In a case where a part of CTVon simulation CT protruded outside ITV, differences of D95 and V90 of CTV, ITV and PTV were up to 7.6% and 13.4%, 2.1% and 18.1%, and 1.9% and 17.0%, respectively. Differences of lung V5, V10, V20 and MLD were up to 3.7%. Conclusions: The isodose lines move together with tumor motion by dose build-up at the tumor, but dose to CTV is maintained within an acceptable range if it moves within ITV. The dose distributions vary with changes of the respiratory phase, and the differences may occur between simulation CT and 4D-CT. Dose distributions should be evaluated not only on a single respiratory phase but on all respiratory phases. Author Disclosure: F. Baba: None. Y. Nonogaki: None. S. Tanaka: None. S. Hasegawa: None. M. Nishihashi: None. S. Ayakawa: None. M. Iwana: None. Y. Shibamoto: None.