Maud Jaccard1, Giorgio Lamanna2, Melpomeni Kountouri2, Michel Rouzaud2, Raymond Miralbell3, Thomas Zilli4. 1. Radiation Oncology, University Hospital of Geneva, Geneva, Switzerland. Electronic address: maud.jaccard@hcuge.ch. 2. Radiation Oncology, University Hospital of Geneva, Geneva, Switzerland. 3. Radiation Oncology, University Hospital of Geneva, Geneva, Switzerland; Radiation Oncology, Teknon Oncologic Institute, Quironsalud, Barcelona, Spain. 4. Radiation Oncology, University Hospital of Geneva, Geneva, Switzerland; Faculty of Medicine, Geneva University, Geneva, Switzerland.
Abstract
PURPOSE: To evaluate the planning feasibility of dose-escalated total marrow irradiation (TMI) with simultaneous integrated boost (SIB) to the active bone marrow (ABM) using volumetric modulated arc therapy (VMAT), and to assess the impact of using planning organs at risk (OAR) volumes (PRV) accounting for breathing motion in the optimization. METHODS: Five patients underwent whole-body CT and thoraco-abdominal 4DCT. A planning target volume (PTV) including all bones and ABM was contoured on each whole-body CT. PRV of selected OAR (liver, heart, kidneys, lungs, spleen, stomach) were determined with 4DCT. Planning consisted of 9-10 full 6 MV photon VMAT arcs. Four plans were created for each patient with 12 Gy prescribed to the PTV, with or without an additional 4 Gy SIB to the ABM. Planning dose constraints were set on the OAR or on the PRV. Planning objective was a PTV Dmean < 110% of the prescribed dose, a PTV V110% < 50%, and OAR Dmean ≤ 50-60%. RESULTS: PTV Dmean < 110% was accomplished for most plans (n = 18/20), while all achieved V110%<50%. SIB plans succeeded to optimally cover the boost volume (median ABM Dmean = 16.3 Gy) and resulted in similar OAR sparing compared to plans without SIB (median OAR Dmean = 40-54% of the ABM prescribed dose). No statistically significant differences between plans optimized with constraints on OAR or PRV were found. CONCLUSIONS: Adding a 4 Gy SIB to the ABM for TMI is feasible with VMAT technique, and results in OAR sparing similar to plans without SIB. Setting dose constraints on PRV does not impair PTV dosimetric parameters.
PURPOSE: To evaluate the planning feasibility of dose-escalated total marrow irradiation (TMI) with simultaneous integrated boost (SIB) to the active bone marrow (ABM) using volumetric modulated arc therapy (VMAT), and to assess the impact of using planning organs at risk (OAR) volumes (PRV) accounting for breathing motion in the optimization. METHODS: Five patients underwent whole-body CT and thoraco-abdominal 4DCT. A planning target volume (PTV) including all bones and ABM was contoured on each whole-body CT. PRV of selected OAR (liver, heart, kidneys, lungs, spleen, stomach) were determined with 4DCT. Planning consisted of 9-10 full 6 MV photon VMAT arcs. Four plans were created for each patient with 12 Gy prescribed to the PTV, with or without an additional 4 Gy SIB to the ABM. Planning dose constraints were set on the OAR or on the PRV. Planning objective was a PTVDmean < 110% of the prescribed dose, a PTV V110% < 50%, and OAR Dmean ≤ 50-60%. RESULTS:PTVDmean < 110% was accomplished for most plans (n = 18/20), while all achieved V110%<50%. SIB plans succeeded to optimally cover the boost volume (median ABM Dmean = 16.3 Gy) and resulted in similar OAR sparing compared to plans without SIB (median OAR Dmean = 40-54% of the ABM prescribed dose). No statistically significant differences between plans optimized with constraints on OAR or PRV were found. CONCLUSIONS: Adding a 4 Gy SIB to the ABM for TMI is feasible with VMAT technique, and results in OAR sparing similar to plans without SIB. Setting dose constraints on PRV does not impair PTV dosimetric parameters.