Verification of cone-beam CT functions for Varian Clinac^® IX linear accelerator

OBJECTIVES

The On-Board Imager^® (OBI) system is designed to correct for
motion and setup errors in patients undergoing radiation therapy.
The OBI system provides three imaging modes: radiographic
and fluoroscopic image acquisition and three-dimensional
cone-beam computed tomography (CBCT) acquisition.
The use of this new technology necessitates a comprehensive
quality assurance (QA) program. In this study, we describe the
procedures of test items included in the QA program and present
the results of measurements.

METHODS

We used Catphan^® 600 phantom for CBCT image quality tests.
We verified density resolution, spatial linearity measurement,
image uniformity measurements, and high resolution and low
contrast resolution.

RESULTS

All measured values were in accordance with acceptance and
limit values.

CONCLUSION

Use of the tests over extended periods showed that the OBI
system has stable image quality. While the results of the measurements
were not exactly the same, they were observed to be
in acceptable limits.

Keywords: Quality control; cone-beam CT; verification