One limitation of CT scanning technology is that bags from suspicious passenger are scanned too slowly. This means only bags from suspicious passengers are scanned. Since this is not that effective,newer high-tech systems have been developed that are capable of detecting chemical components in individual itiems. The X-ray scanners most people see in airports are for screening carry-on bags. But theses scanners are too small to scan all the luggage that goes into the cargo section of the plane. In busy airports,large trucks with built-in X-ray scanners(up to 5~7 meters long)al are used. These truck pull up beside containers that hold the suitcases,bags and other cargo. The entire container is scanned at once.