The conformal nature of intracranial stereotactic radiotherapy means that verification using electronic portal imaging is limited due to the inherent difficulties in analyzing small irregular non-coplanar fields. The use of orthogonal imaging protocols that compare portal images centred through the treatment isocentre to CT constructed DRR’s increases the radiation exposure to sensitive neighbouring structures. Other verification methods involving measurements from surface structures are time consuming and difficult to validate. AlignRT provides a method of verifying the treatment position of these patients without the need for radiation exposure.

CT
The patient is scanned as normal and the CT data may then be exported from the planning system to AlignRT as a DICOM RT structure to be used as a reference image. The reference image can be moved within AlignRT so that the isocentre is moved from the CT isocentre to the Isocentre position as defined by the planning process.

Treatment
The patient is positioned using conventional methods and a surface image is acquired. This is then matched directly to the CT reference image and coordinates are output in all six degrees of freedom.

< Back to AlignRT® in action