Figure 1.

Procedure workflow. Patients undergo non-invasive visualization with computed tomography, echocardiography, and cardiovascular magnetic resonance according to clinical routine. Anatomical information obtained from the above imaging procedures is used to develop the radiation volume, which is called ‘multi-image matching’. The target volume is transferred by the radiation oncologist onto a respiratory-correlated, four-dimensional computed tomography scan, which allows an assessment of the total cardiac and pulmonary motion. In this example, a dose of 25 Gy in a single fraction is prescribed for delivery to the target volume, with the goal of achieving maximal coverage inside the volume while avoiding exposure to the surrounding organs at risk. The target volume is indicated in a red cube in the figure panel showing the treatment plan; a green dot indicates the His bundle. The patient is immobilized with the use of a vacuum-assisted device, and stereotactic radiation is performed by means of an image-guided, radiotherapy-equipped linear accelerator. After treatment, the clinical and haemodynamic conditions are monitored by electrocardiogram, echocardiography, or cardiovascular magnetic resonance during 12 months follow-up.