SGRT can accurately monitor VMAT DIBH breast radiotherapy patients. Camera occlusion may provide difficulties for SGRT systems, such as VisionRT’s AlignRT, during rotational imaging (CBCT) and treatments (VMAT). Therefore, appropriate regions of interest (ROIs) need definition to ensure robust monitoring. Equally, operators must know where camera occlusion most likely occurs to optimise workflows.

A CT scan of an anthropomorphic phantom was performed to mimic a breast patient’s DIBH treatment position. A VMAT plan was produced, and six ROIs drawn on an AlignRT terminal. An ROI sensitivity test was performed, and approximate percentage surface area of occlusion was determined for all ROIs. Postural video was also utilised to determine where camera occlusion is most likely to occur.

No full camera occlusion was demonstrated using the phantom. However, postural video demonstrated camera occlusion was more probable between 10 and 60 degrees for CBCT arcs due to lateral camera occlusion. Sensitivity test results showed ROIs were more sensitive to vertical and lateral translations when both lateral cameras are blocked at CBCT50. Larger ROIs may be less sensitive and more robust when cameras were occluded. Additionally, the greatest approximate percentage of occlusion occurred at the superior lateral aspects of ROIs.

Gantry angles at higher risk of camera occlusion have been described between 10 and 60 degrees for CBCT to assist operators with troubleshooting, and a clinical workflow proposed. An ROI for VMAT DIBH breast rotational imaging and treatment has also been suggested to reduce the impact of camera occlusion.

Surface-guided radiotherapy (SGRT) allows patient prepositioning based on a 3D surface instead of conventional skin marks. The primary aim was to investigate the feasibility of SGRT using ExacTrac Dynamic (ETD) for prepositioning patients receiving breast radiotherapy in free breathing compared to conventional skin-marker setup, secondary to assess intrafraction motion using surface data.

Twenty-one patients receiving whole- or partial-breast radiotherapy in free breathing were included. Each patient was set up using both skin marks and SGRT for different fractions in a non-systematic order. The setup offset was evaluated using 3D couch shifts from subsequent image guidance. Intrafraction motion was analysed for all monitor units (MU) delivered, and systematic patient movement was assessed by analysing the average surface shift per main tangential field compared to baseline. The shift between main fields represented the intrafraction movement.

No significant difference was found in mean population setup offset between SGRT and skin-marker setup. SGRT demonstrated reduced random errors in vertical and longitudinal direction and reduced systematic errors in lateral direction. Intrafraction motion was limited with a vector displacement of 0·9 mm. A small but significant inter-field movement of −0·3 mm was, however, detected vertically.

Surface-guided setup using ETD is a viable alternative for prepositioning patients receiving breast radiotherapy in free breathing compared to conventional skin-marker setup. It is, however, advisable to use subsequent IGRT for final positioning. Patient motion can be tracked effectively using ETD surface monitoring.

Accurate delivery of radiotherapy to head, neck and brain cancer relies on the use of sophisticated immobilisation devices, usually using a restrictive thermoplastic mask. These masks can cause anxiety and can make treatment difficult for many patients. Open-face or maskless techniques are alternatives which can improve the patient experience. This systematic review aimed to compare the effectiveness of open-face (OF) masks and maskless surface guided radiotherapy (SGRT) with conventional masks.

Primary research papers from the last 10 years were gathered from Scopus, PUBMED, Web of Science and OVID databases. Quantitative data reporting interfractional set-up errors and intrafractional patient motion were extracted from included studies and subjected to descriptive statistical analysis. Additional qualitative data relating to patient tolerance were also extracted to inform discussion.

Ten studies were identified for inclusion. The data identified that OF masks can reproduce patient set-up with an accuracy of <2 mm and <1° and can restrict movement to <1 mm and 0·4°, while maskless SGRT can achieve accuracy to within 0·05 mm and 0·1°.

This review indicates comparable reduction of intrafractional motion between conventional masks, Open-Face masks and maskless SGRT techniques. More research is needed into the impact of maskless SGRT techniques on translational and rotational motions compared to traditional masks.