Comparative treatment planning of photon, proton and carbon ion radiotherapy for sphenoid wing meningiomas

Background and purpose Sphenoid wing meningiomas (SWMs) are located adjacent to critical organs of interest (OOIs) and present challenges for surgery and radiotherapy. Given the favorable overall survival in meningioma patients, preserving quality of life is important. Dose reductions within OOIs may lower adverse events. This study aimed to evaluate potential advantages of particle therapy regarding dose distribution and side effects for SWMs. Materials and methods Nine patients (eight females, one male; median age at radiotherapy: 55 years) with SWM received proton radiotherapy (PRT, 54 Gy (RBE), 1.8 Gy (RBE) per fraction) at Heidelberg Ion-Beam Therapy Center (2014–2022). Comparative treatment plans were generated for volumetric modulated arc therapy (VMAT, 54 Gy, 1.8 Gy per fraction) and carbon ion radiotherapy (CIRT, 42 Gy (RBE), 3 Gy (RBE) per fraction). Target volumes and OOI dose guidance were maintained. OOI dose-volume parameters, normal tissue complication probabilities (NTCP), and risk ratios of radiation-induced secondary central nervous system (CNS) malignancies were assessed. Results Compared to VMAT, mean relative brain doses were reduced by −41.5% with PRT, and − 63.8% with CIRT. Particle therapy achieved significant dose sparing of bilateral hippocampi and lenses, and the ipsilateral inner ear. NTCPs indicated lower risks of ipsilateral hearing loss and cataract with particle therapy. The mean estimated risk of radiation-induced secondary malignancies was 1.7 for photons over protons, and 2.7 for photons over carbon ions. Conclusions For SWMs, particle therapy demonstrated reduced dose exposure to several OOIs, and may lower the risk of side effects compared with VMAT.