ESTRO 2023 - Abstract Book

S1370

Digital Posters

ESTRO 2023

Figure: Long axial field-of-view PET/CT-scan in deep inspiration breath hold of a patient with mediastinal and bilateral neck involvement Conclusion Conclusion: Pre-chemotherapy DIBH PET/CT performed on a LAFOV PET/CT scanner makes the post-chemotherapy planning of DIBH RT easier and more accurate, enabling greater conformity and normal tissue sparing.

PO-1668 An evaluation of a novel CBCT system: image quality, extended FoV and metal artefact reduction

G. Paiva Fonseca 1 , D. Lustermans 1 , M. Bogowicz 1 , V. Taasti 1 , F. Vaassen 1 , R. Canters 1 , K. Theeuwen 1 , W. van Elmpt 1 , F. Verhaegen 1 1 Maastricht University Medical Centre+, Department of Radiation Oncology (MAASTRO), GROW – School for Oncology and Reproduction, Maastricht, The Netherlands Purpose or Objective A novel cone-beam CT (CBCT) imager including advanced reconstruction capabilities was developed for optimized radiotherapy workflow. This study evaluates this CBCT (HyperSightTM integrated on a Halcyon v4.0 (pre-market release), Varian Medical Systems) for image quality of fast CBCTs (acquisition time of 5.9 s) and novel features such as extended FoV (eFoV) up to 70 cm and two reconstruction techniques (iCBCT Acuros and iCBCT MAR for metal artefacts reduction) introduced in this version. Materials and Methods CBCTs were acquired using multiple commercial phantoms (Figure 1) and reconstructed using FDK and iterative reconstruction (iCBCT Acuros and iCBCT MAR). HU accuracy was evaluated using tissue-mimicking inserts (Gammex, Sun Nuclear) in multiple positions within anthropomorphic phantoms and cylindrical phantoms with diameters from 20 up to 40 cm. A large 3D-printed breast phantom designed for eFoV was used to evaluate geometrical and HU accuracy outside (up to 70 cm) of the standard FoV (54 cm; sFoV). In addition, image resolution and contrast were also evaluated using Catphan and MAR was evaluated using a CIRS head phantom with tooth and metal spine implants. Results were compared with fan beam CT images (Siemens SOMATOM Drive).