365 / 1456
Online or offline?
Online
• Imaging each fraction
• More time on the linac
• Corrects random and
systematic errors
• Correction procedure needs to
be fast
• Correction usually only a
couch shift
• Smaller effect on margin
Offline
• Limited imaging
• Time efficient
• Only corrects systematic errors
• Correction procedure can take
a long time
• Correction can be a re-plan
• Largest effect on the margin