Silvia Molinelli1, Maria Bonora2, Giuseppe Magro2, Silvia Casale3, Jon Espen Dale4, Piero Fossati5, Azusa Hasegawa6, Alfredo Mirandola2, Sara Ronchi2, Stefania Russo2, Lorenzo Preda7, Francesca Valvo2, Roberto Orecchia8, Mario Ciocca2, Barbara Vischioni2. 1. Clinical Department, National Center for Oncological Hadrontherapy (CNAO), Pavia, Italy. Electronic address: molinelli@cnao.it. 2. Clinical Department, National Center for Oncological Hadrontherapy (CNAO), Pavia, Italy. 3. Department of Diagnostic Medicine, Institute of Radiology, IRCCS San Matteo University Hospital Foundation, Pavia, Italy. 4. Department of Oncology and Medical Physics, Haukeland University Hospital, Bergen, Norway. 5. MedAustron Ion Therapy Center, Wiener Neustadt, Austria. 6. Osaka Heavy Ion Therapy Center, Osaka, Japan. 7. Clinical Department, National Center for Oncological Hadrontherapy (CNAO), Pavia, Italy; Department of Clinical-Surgical, Diagnostic and Paediatric Sciences, University of Pavia, Italy. 8. Clinical Department, National Center for Oncological Hadrontherapy (CNAO), Pavia, Italy; European Institute of Oncology, Milan, Italy.
Abstract
PURPOSE/ OBJECTIVE: The purpose of this study is to assess the impact of the conversion scheme for relative biological effectiveness (RBE)-weighted dose (DRBE), implemented at our center, on treatment outcomes of adenoid cystic carcinoma (ACC) patients. MATERIAL/ METHODS: Treatment plans of 78 ACC patients, optimized with the Local Effect Model (LEM), were recalculated with the modified Microdosimetric Kinetic Model (mMKM). DRBE to 95%, 50% and 2% (DV%) of the clinical target volume (CTV), were selected as relevant parameters to compare LEM and mMKM DRBE. The pattern of failure of ACC treatments was analyzed in relation to uncertainties involved in the DRBE translation methodology. RESULTS: mMKM recalculations of LEM plans, optimized to a prescription dose of 68.8 Gy(RBE), showed a D50% 8% higher, on average, than the expected value (60.8 Gy(RBE)), closer to the most frequently used mMKM prescription DRBE (64 Gy(RBE)). D95% and D2% deviations, with respect to the optimization goals in the two RBE systems, increased of 0.5% and 14.2%, respectively, due to the steeper mMKM RBE variation along the beam path. Local recurrences were mainly (63%) reported in areas where CTV coverage was not satisfactory in the original LEM plan and the mMKM analysis showed that OARs constraints were too conservative. CONCLUSION: No case of local recurrence could be explained by inadequate mMKM target coverage that was not already present in the LEM plan. New constraints have been defined for optic pathways and brainstem to improve target coverage with no expected increase in tissue complications.
PURPOSE/ OBJECTIVE: The purpose of this study is to assess the impact of the conversion scheme for relative biological effectiveness (RBE)-weighted dose (DRBE), implemented at our center, on treatment outcomes of adenoid cystic carcinoma (ACC) patients. MATERIAL/ METHODS: Treatment plans of 78 ACC patients, optimized with the Local Effect Model (LEM), were recalculated with the modified Microdosimetric Kinetic Model (mMKM). DRBE to 95%, 50% and 2% (DV%) of the clinical target volume (CTV), were selected as relevant parameters to compare LEM and mMKM DRBE. The pattern of failure of ACC treatments was analyzed in relation to uncertainties involved in the DRBE translation methodology. RESULTS: mMKM recalculations of LEM plans, optimized to a prescription dose of 68.8 Gy(RBE), showed a D50% 8% higher, on average, than the expected value (60.8 Gy(RBE)), closer to the most frequently used mMKM prescription DRBE (64 Gy(RBE)). D95% and D2% deviations, with respect to the optimization goals in the two RBE systems, increased of 0.5% and 14.2%, respectively, due to the steeper mMKM RBE variation along the beam path. Local recurrences were mainly (63%) reported in areas where CTV coverage was not satisfactory in the original LEM plan and the mMKM analysis showed that OARs constraints were too conservative. CONCLUSION: No case of local recurrence could be explained by inadequate mMKM target coverage that was not already present in the LEM plan. New constraints have been defined for optic pathways and brainstem to improve target coverage with no expected increase in tissue complications.
Authors: Edoardo Mastella; Silvia Molinelli; Giuseppe Magro; Stefania Russo; Maria Bonora; Sara Ronchi; Rossana Ingargiola; Alexandra D Jensen; Mario Ciocca; Barbara Vischioni; Ester Orlandi Journal: Front Oncol Date: 2021-12-13 Impact factor: 6.244
Authors: Barbara Vischioni; Stefania Russo; Martino Meuli; Maria Bonora; Sara Ronchi; Rossana Ingargiola; Anna Maria Camarda; Sara Imparato; Lorenzo Preda; Mario Ciocca; Silvia Molinelli; Ester Orlandi Journal: Front Oncol Date: 2022-03-02 Impact factor: 6.244