Image quality improvement for medium and large field of view Elekta XVI scans

  • David P. LittleEmail author
Scientific Paper


Cone-beam computed tomography (CBCT) has become the standard imaging technique for many sites treated with Radiotherapy. The Elekta X-ray Volumetric Imaging (XVI) system allows for the acquisition of CBCTs with three different diameters; small (27 cm), medium (41 cm) and large (50 cm) (Elekta in XVI Corrective Maintenance Manual R5.0, Elekta, Stockholm, 2013). Images are used to ensure accurate patient positioning as well as checking for changes in the patient contour or internal geometry, and image quality must be high enough to achieve these goals. This paper describes two simple adjustments which can lead to improved image quality for medium and large field of view (MFOV and LFOV) scans. The first involves measuring a default distance in the XVI software (kV Source to Detector Distance) to improve spatial resolution and geometric scaling of both MFOV and LFOV scans. The second involves correcting a uniformity issue seen at our centre with LFOV scans, allowing us to use this FOV for assessing patient contour changes on large patients. The implementation and effects of both adjustments are explored in this paper, and workflows are proposed for optimising both parameters.


Elekta XVI CBCT Image quality 



No funding was received for this study.

Compliance with Ethical Standards

Conflict of interest

The author David Little declares that he has no conflict of interest.

Research with animal and human participants

This article does not contain any studies with human participants or animals performed by any of the authors.

Informed consent

No informed consent was required.


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Copyright information

© Australasian College of Physical Scientists and Engineers in Medicine 2019

Authors and Affiliations

  1. 1.Canterbury District Health BoardChristchurch HospitalChristchurchNew Zealand

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