Effect of Magnetic Endoscopic Imaging on Patient Pain During Colonoscopy

In the first part,patients would be randomly assigned to have colonoscopy examination performed by one inexperienced colonoscopist (having performed less than 200 procedures) with the assistance of magnetic scope navigation system In the second part colonoscopist would be randomized to perform conventional colonoscopy on a colon model with an MEI view while the force measurement device being used to collect data of colon force variation meanwhile. No patients would be involved in this part. All force variation data would be recorded by a image storage device.