ESTRO 2021 Abstract Book

S1281

ESTRO 2021

Fig. 1: 4D dose distribution subtracted from original treatment plan (original - 4D dose). This specific case was planned and simulated with RA technique with 15 fractions.

Conclusion There was a slight decrease in PTV dose coverage under free breathing conditions for RA and VMAT techniques. The statistical test was indecisive for changes in PTV coverage for FinF technique. Dose to the critical organs remained unchanged. The impact of free breathing and fractionation on the simulated dose was small and thus VMAT can be considered a feasible technique in hypofractionated WBI treatment. PO-1556 Evaluation of the new Brainlab Exactrac Dynamic structured light positioning system R. Astudillo 1 , M. Gutierrez Ruiz 2 , J. Alonso Muriedas 1 , S. Ruiz Arrebola 3 , M.T. Pacheco Baldor 4 , J.A. Vázquez Rodriguez 5 , J.I. Raba Díez 3 , V. Cañon Garcia 4 , A.L. Rivero Perez 4 , J. Albendea Roch 4 , U.A. Corro Verde 4 , M. Ferri Molina 4 , I. Diaz de Cerio Martinez 4 , R. Fabregat Borrás 4 1 Hospital Universitario Marqués de Valdecilla, Radiation Oncology Department, Santander, Spain; 2 Hospital Universitario Marqués de Valdecill, Radiation Oncology Department, Santander, Spain; 3 Hospital Universitario Marqués de Vadecilla, Radiation Oncology Department, Santander, Spain; 4 Hospital Universitario Marqués de Vadecilla , Radiation Oncology Department, Santander, Spain; 5 Hospital Universitario Marqués de Vadecilla, Radiation Oncology Department, Santander, Spain Purpose or Objective The new Brainlab Exactrac Dynamic system (ED) consists of two kV X-Ray tubes mounted on the floor, two ceiling mounted flat panel detectors and a single ceiling mounted receptacle that contains a structured light (SL) projector, two high resolution cameras and an integrated thermal camera. The system pre-positions the patient by matching the live 3D surface with the external contour. Then, ED performs final positioning based on stereoscopic X-Ray images. During treatment, ED performs intra-fraction monitoring combining 2D thermal data with 3D surface information.