@article {Arns2016,
	title = {Towards clinical implementation of ultrafast combined kV-MV CBCT for IGRT of lung cancer: Evaluation of registration accuracy based on phantom study },
	journal = {Strahlentherapie und Onkologie},
	volume = {192},
	year = {2016},
	abstract = {<p>{\textcopyright} 2016, Springer-Verlag Berlin Heidelberg.Purpose: Combined kV-MV cone-beam CT (CBCT) is a promising approach to accelerate imaging for patients with lung tumors treated with deep inspiration breath-hold. During a single breath-hold (15{\^A}\&nbsp;s), a 3D kV-MV CBCT can be acquired, thus minimizing motion artifacts and increasing patient comfort. Prior to clinical implementation, positioning accuracy was evaluated and compared to clinically established imaging techniques. Methods and materials: An inhomogeneous thorax phantom with four tumor-mimicking inlays was imaged in 10 predefined positions and registered to a planning CT. Novel kV-MV CBCT imaging (90{\^A}{\textdegree}{\^A}\&nbsp;arc) was compared to clinically established kV-chest CBCT (360{\^A}{\textdegree}) as well as nonclinical kV-CBCT and low-dose MV-CBCT (each 180{\^A}{\textdegree}). Manual{\^A}\&nbsp;registration, automatic registration provided by the manufacturer and an additional in-house developed manufacturer-independent framework based on the MATLAB registration toolkit were applied. Results: Systematic setup error was reduced to 0.05{\^A}\&nbsp;mm by high-precision phantom positioning with optical tracking. Stochastic mean displacement errors were 0.5 {\^A}{\textpm} 0.3{\^A}\&nbsp;mm in right{\^a}{\texteuro}{\textquotedblleft}left, 0.4 {\^A}{\textpm} 0.4{\^A}\&nbsp;mm in anteroposterior and 0.0 {\^A}{\textpm} 0.4{\^A}\&nbsp;mm in craniocaudal directions for kV-MV CBCT with manual registration{\^A}\&nbsp;(maximum errors of no more than 1.4 mm). Clinical kV-chest CBCT resulted in mean errors of 0.2{\^A}\&nbsp;mm (other modalities: 0.4{\^a}{\texteuro}{\textquotedblleft}0.8{\^A}\&nbsp;mm).{\^A}\&nbsp;Similar results were achieved with both automatic registration methods. Conclusion: The comparison study of repositioning accuracy between novel kV-MV CBCT and clinically established volume imaging demonstrated that registration accuracy is maintained below 1{\^A}\&nbsp;mm. Since imaging time is reduced to one breath-hold, kV-MV CBCT is ideal for image guidance, e.g., in lung stereotactic ablative radiotherapy.</p>},
	keywords = {Image-guided radio, [Cone-beam computed tomography},
	issn = {1439099X 01797158},
	doi = {10.1007/s00066-016-0947-2},
	author = {Arns, A. and Blessing, M. and Fleckenstein, J. and Stsepankou, D. and Boda-Heggemann, J. and Simeonova-Chergou, A. and Hesser, J. and Lohr, F. and Wenz, F. and Wertz, H.}
}
