CT colonography is known in full as computed tomography colonography (sometimes the word computerised is used instead of computed). It is a test that uses a CT scanner to produce pictures of the inside of the colon and rectum (the colon, or large intestine, is the last part of the intestines or guts, the rectum is the passage between the colon and the anus).
This is a companion discussion topic for the original article at https://patient.info/cancer/colon-rectal-bowel-cancer-colorectal/ct-colonography