Intervention
Radiation:
• Carbon Ion Radiotherapy
Patients will be immobilized using an individually manufactured head mask for treatment planning and RT. Contrast-enhanced CT as well as MR-imaging will be performed for target volume definition. OAR such as the brain stem, optic nerves, chiasm and spinal chord will be contoured. The fractionation scheme will be taken into account for dose prescription, as well as DVH-characteristics and clinical parameters of the invidivual patient.
The Gross Tumor Volume (GTV) will be defined as the contrast-enhancing lesion on MRI on T1-weighted MR-imaging. Amino-Acid-PET or DOTATOC-PET may be used in addition to contrast-enhanced MRI for target volume definition but is not mandatory.The Clinical Target Volume (CTV) will be defined adding 1-2mm safety margin to the GTV.
• Proton Therapy
As described previously, patients will be immobilized using an individually manufactured head mask for treatment planning and RT. Contrast-enhanced CT as well as MR-imaging will be performed for target volume definition. OAR such as the brain stem, optic nerves, chiasm and spinal chord will be contoured. Dose constraints of normal tissue will be respected according to Emami et al. (33). The fractionation scheme will be taken into account for dose prescription, as well as DVH-characteristics and clinical parameters of the invidivual patient.
The Gross Tumor Volume (GTV) will be defined as the contrast-enhancing lesion on MRI on T1-weighted MR-imaging. Amino-Acid-PET or DOTATOC-PET may be used in addition to contrast-enhanced MRI for target volume definition but is not mandatory.The Clinical Target Volume (CTV) will be defined adding 1-2mm safety margin to the GTV.
• Hypofractionated Photon Radiotherapy
Treatment Planning for Photon Radiotherapy will be performed using the Planning Systems available at the Department of Radiation Oncology in Heidelberg, Germany (including Masterplan/Nucletron, Virtuos-Konrad/Siemens, or Precisis/STP/Stryker-Leibinger, or the Tomotherapy Software). Carbon ion and proton RT planning is performed using the treatment planning software PT-Planning (Siemens, Erlangen, Germany) including biologic plan optimization. Biologically effective dose distributions will be calculated using the a/ß ratio for meningioma as well as for the endpoint late toxicity to the brain. Patient positioning prior to radiotherapy will be evaluated by comparison of x-rays to the DRRs. Set up deviations >3mm are corrected prior to radiotherapy.
To the target volume defined for photon treatment, a total dose of 52.2 Gy E - 57.6 Gy E is applied in single fractions of 1.8Gy E. In the 3Gy E Photon arm, photon radiotherapy will be delivered to a total dose of 45 Gy E in 15 fractions.
• Conventional Photon Radiotherapy
Treatment Planning for Photon Radiotherapy will be performed using the Planning Systems available at the Department of Radiation Oncology in Heidelberg, Germany (including Masterplan/Nucletron, Virtuos-Konrad/Siemens, or Precisis/STP/Stryker-Leibinger, or the Tomotherapy Software). Carbon ion and proton RT planning is performed using the treatment planning software PT-Planning (Siemens, Erlangen, Germany) including biologic plan optimization. Biologically effective dose distributions will be calculated using the a/ß ratio for meningioma as well as for the endpoint late toxicity to the brain. Patient positioning prior to radiotherapy will be evaluated by comparison of x-rays to the DRRs. Set up deviations >3mm are corrected prior to radiotherapy.