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EPIDs: Pros and cons
Isocentric alignment: the
imaging beam is the
treatment beam (obs:
gravity)
The imaging dose to the
patient can be easily
calculated in the TPS
Verifies the field outline
with respect to the patient
anatomy
Can use the EPID for
transmission (in vivo)
dosimetry
Monoscopic: needs several
angles for 3D positioning
information
Considerable dose for large
FOV images outside the target
volume (1 to 5 MU per image)
Low contrast (bony structures
or markers)