ESTRO 2023 - Abstract Book

S1828

Digital Posters

ESTRO 2023

Figure 1. Average DVH for PTV (A), rectum (C) and bladder (E); and average DDH for normal tissue (B), rectum (D) and bladder (F).

Conclusion VOLO optimizer significantly improved the treatment plan quality as compared to SO. Significant reduction in bladder and rectum doses were seen after the upgrade from SO to VOLO. As compared to SO steeper dose gradients towards bladder and rectum were created with VOLO without compromising the dose gradient in other directions nor increasing the mean body dose.

PO-2053 Assessment of the GE Metal Artifact Reduction option in CTs used for dose calculations with Eclipse

S. Linsalata 1 , R. Borgheresi 2

1 Azienda Ospedaliera Universitaria Pisana, Medical Physics Unit, Pisa, Italy; 2 Azienda Ospedaliera Universitaria Senese, Medical Physics Unit, Siena, Italy Purpose or Objective To assess the impact of the GE Metal Artifact Reduction (MAR) option on dose calculation accuracy for the Acuros XB (AXB) and Analytical Anisotropic Algorithm (AAA) Varian photon algorithms. Materials and Methods A CIRS 062MA Electron Density phantom with high density optional insert was imaged in a GE DiscoveryRT CT simulator with and without the MAR option to obtain two HU-to-density correction tables. A slab PMMA phantom (44x11x16 cm^3 and density 1.183 g/cm^3) with a removable insert of titanium (22x2x2 cm^3 and density 4.506 g/cm^3) was imaged with the two same imaging protocols. Dose calculations in these two slab phantom CTs were done after the application of the proper HU-to-density curve. Due to AXB calculation properties (i.e., the upper limit density of 3 g/cm^3 for the use of the HU-to- density automatic conversion) the exact volume of the titanium insert was overridden with the HU corresponding to the real insert density, namely HU=5611 with MAR and HU=6343 without MAR. No override was necessary for the AAA algorithm.