If you use respiratory gating for liver SBRT, what is your preferred method?

What method do you prefer to use for respiratory motion management when doing liver SBRT?

• Respiratory gating, surface-based with a reflector (i.e. RPM)
• Respiratory gating with an internal or external marker (i.e. triggered imaging and automated beam hold)
• Breath hold with intrafractional motion tracking, e.g. with surface guidance or internal beacons
• Breath hold without intrafractional motion tracking
• Abdominal compression alone with or without an ITV or iGTV
• Free breathing with an ITV or iGTV
• Real time tumor tracking (i.e. Cyberknife)
• Other