The clinician may then use the FastEEM4 and/or the POS systems. If the FastEEM4 and/or POS systems are used, you will have a FastEEM4 and/or POS probe(s) placed gently on the mouth lesion(s). Several measurements will then be taken by moving the probe(s) a short distance at a time, toward the edge of the lesion(s), until it measures what appears to be normal mouth tissue.