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EP-1655: VMAT FFF irradiation in deep inspiration breath hold

J. Demoucron, J.L. Dumas, A. Hadj Henni, E. Costa, M. Robilliard, A. Mazal
2016 Radiotherapy and Oncology  
Purpose or Objective: Clinical target volumes (CTV) in the head and neck region are typically located just beneath the skin. Therefore, planning target volumes (PTV) will be outside the body contour. Moreover, for IMRT and VMAT treatment plans the build-up region is excluded from the PTV in the treatment planning system and optimization is done on the remaining part of the PTV (in our institute excluding the PTV outside the patient and a margin of 4 mm beneath the skin). This study evaluates
more » ... study evaluates the robustness of such treatment plans to set-up errors. Material and Methods: Seven head-and-neck treatment plans were evaluated (VMAT, SIB with 54.25 Gy to the CTV and 70 Gy to the CTVboost in 35 fractions, CTV to PTV margins were 3 mm, Pinnacle Treatment Planning system). To investigate the effect of set-up errors on CTV coverage, a patient-shift on the treatment table is simulated as a shift of the isocenter. The isocenters were shifted in steps of 1 mm up to 10 mm for each of these treatment plans, in both directions ("into the patient" and "out of the patient", see Figure 1a ; direction chosen in such a way that shifts out of the patients have the most effect). Subsequently, it was evaluated up till which step in mm the DVHs of the simulated (shifted) treatment plans were clinically acceptable (V95% > 99%). Purpose or Objective: To evaluate the dosimetric effect of placing the isocenter away from the planning target volume on intensity-modulated radiosurgery (IMRS) plans to treat brain lesions. Material and Methods: Fifteen patients, who received cranial IMRS at our institution, were randomly selected. Each patient
doi:10.1016/s0167-8140(16)32906-1 fatcat:rzy2qmxuq5cl7pdvpm7br2qmvq