Quality control tests of kV-CBCT imaging with Catphan phantom and automated analysis with Artiscan software.

Abstract

Image Guided Radiotherapy has become a widely accepted and recommended method of treatment in recent years. IGRT allows for very precisely patient positioning before the delivery of the therapeutic beam, increasing the precision of treatment and reducing the dose of radiation deposited in healthy tissue and critical organs. The main purpose of this work was to perform quality control tests of the kV-CBCT imaging system, determinate reference values for all parameters and to develop QA protocols used in daily routine work. All of QA protocols were developed with Artiscan software. Imaging tests have been performed on TrueBeam linear accelerator from Varian Medical System and Catphan 504 phantom, for two acquisition protocols: Head and Pelvis. The following parameters describing image quality were determined during the study: linearity of the Hounsfield Unit scale, high contrast resolution, low contrast resolution, geometric distortion, noise level, homogeneity. The noise level was 2.75% for the Head protocol and 0.85% for the Pelvis protocol, uniformity was 94% and 98%. All calculated Hounsfield Unit values ​​were within the accepted tolerance range. High contrast resolution was 7.70lp/mm for Head and 5.59lp/mm Pelvis scanning protocols. For the Pelvis  protocol, a 15mm diameter object during Supra-Slice 1% conditions has been detected in every measurement series. No geometrical distortion of the image was observed. The developed Quality Assurance protocols are used in clinical routine.