Typically, 3 to 6 fiducial markers are placed around a tumor during an outpatient procedure called endoscopic ultrasound (EUS)
. A thin, flexible tube (endoscope) is inserted through the mouth, down the esophagus, past the stomach and into the area of the tumor. A thin needle is inserted through the tube into the tumor to place the fiducial markers. The endoscope contains a tiny camera, which transmits pictures to a monitor so a doctor can see inside as the markers are placed.
You must wait a week or so after having markers placed before beginning radiation therapy.