Table 1.
Overview of the technologies used for real-time motion monitoring.
| Technology (section) | Internal/external | Dimensions | Additional ionising radiation | Tissue/tumour/surrogate | Additional equipment to standard linac | Online solution (vendor) if applicable |
|---|---|---|---|---|---|---|
| Infrared (2.1.1) | External | 1D | No | Patient surface | No | RPM (Varian) respiratory gating (figure 1(a)) |
| 6 DoF | Fixation devices | Yes | IRLED (Brainlab) | |||
| Optical (2.1.2) | External | 6 DoF surface | No | Patient surface | Yes | Align RT (vision RT) (figure 1(b))/catalyst (C-RAD) |
| Spirometry (2.1.3) | External | 1D | No | Lung volume changes | Yes | ABC (Elekta) (figure 1(c)) |
| Pressure belt (2.1.3) | External | 1D | No | Abdomen perimeter | Yes | Anzai (Anzai Medical) (figure 1(d)) Bellows |
| Thermistor (2.1.3) | External | 1D | No | Airflow temperature | Yes | Thermistor (non commercial) |
| kV/MV (2.2.2) | Internal | 3D triangulated | Yes | Markers (prostate) | No | MSKCC (non commercial) |
| kV/kV (2.2.2) | Internal | 3D triangulated | Yes | Markers (multi-site), vertebrae, Cranium | Dedicated machine | CyberKnife® (Accuray) (figure 2(c) top) |
| Markers (multi-site) | Dedicated machine | Vero (figure 2(c) bottom) (Brainlab and Mitsubishi, discontinued) | ||||
| Markers (multi-site) | Yes | RTRT (non commercial) | ||||
| Lung and liver tumours | Yes | Stereoscopic markerless monitoring (non commercial) | ||||
| MV (2.2.3) | Internal | 2D beam’s eye view | No | Markers, lung tumour | No | No online solution |
| 3D inferred | Markers (prostate) | |||||
| kV (2.2.3) | Internal | 3D inferred | Yes | Markers (multi-site), vertebrae, bronchi, lung tumours | No | KIM (non commercial, online only for prostate) and sequential stereoscopic (non commercial, online only for vertebrae) |
| 6D inferred | Markers | KIM, not performed online | ||||
| Hybrid (2.3) | Internal with correlation model | 3D | Yes | Markers (multi-site), lung tumours | Dedicated machine | CyberKnife® Synchrony (Accuray) (figure 2(c) top) |
| Markers (multi-site) | Dedicated machine | Vero (figure 2(c) bottom) (Brainlab and Mitsubishi, discontinued) | ||||
| Markers (multi-site), cranium | Yes | ExacTrac (Brainlab) (figure 2(b)) | ||||
| Markers (lung) | Yes | RTRT + Anzai (non commercial) | ||||
| Markers (liver) | No | COSMIK (non commercial) | ||||
| Electromagnetic (2.4.1) | Internal | 3D | No | Markers (multi-site) | Yes | Calypso (Varian) and rayPilot (MicroPos Medical, only prostate) (figure 5) |
| Ultrasound (2.4.2) | Internal | 3D | No | Prostate, prostate bed | Yes | Clarity autoscan (Elekta) (figure 5(d)) |
| Soft tissues | Modified 4D ultrasound system (non commercial) | |||||
| MR (2.5) | Internal | 2D cine (any orientation) | No | Tissues | Dedicated machine | Unity (Elekta), MRIdian (ViewRay) (figure 2(d)) |