ESTRO 2023 - Abstract Book

S1393

Digital Posters

ESTRO 2023

Conclusion We characterized the dose calculation accuracy for a novel CBCT imager. Very good agreement between dose calculations performed on the CBCT and planning CT was observed. MAR reconstruction provided good dose accuracy when a large implant was placed close to the target. This novel CBCT system with enhanced image quality and CT number accuracy opens a large variety of possibilities for direct off-line and online re-planning.

PO-1684 Characterization of A Novel High-Performance Cone Beam Computed Tomography Imaging System

T. Zhao 1 , A. Price 1 , E. Laugerman 1 , Y. Hao 1 , N. Knutson 1 , H. Li 1 , L. Henke 1 , P. Samson 1

1 Washington University in St. Louis, Radiation Oncology, St. Louis, USA

Purpose or Objective Image quality of a novel, high-performance cone beam computed tomography (CBCT) imaging system was measured and reported in this study. Materials and Methods A re-engineered CBCT imaging panel with the doubled to 86cm x43cm for a full field of view (FOV) of 55.8cm in diameter and extendable to 70 cm was installed by the vendor on a commercial o-ring linear accelerator. A thicker layer of CsI crystal scintillator replaced Gadolinium Oxysulfide for better light yield and higher imaging resolution. The gantry rotation speed was increased to 10 rotations per minute. Combined with the new imaging panel, a 211o rotation was deemed enough for a full CBCT reconstruction. This improvement reduced the acquisition time to 5.9 seconds. A new reconstruction mode based on a linear Boltzmann transport solver was introduced to reduce the imaging artifact from scattering. The CBCT system provides four tube voltages ( 80 kVp, 100 kVp, 125 kVp and 140 kVp) for image-guided radiotherapy (IGRT) and the latter two of the four tube voltages was used for planning (CBCTp) purpose. In this study, we tested the important imaging quality parameters such as imaging distortion, resolution, slice thickness, uniformity, and the contrast-to-noise ratio reconstructed with iterative CBCT (iCBCT) and iterative CBCT on a Boltzmann transport equation solver (iCBCTAcuros) reconstructions on Catphan modules 528, 404, and 486. Tube voltages, exposures, scanning speed, and imaging dose were