Method for performing security screening at a security checkpoint, said method comprising: a) performing with a same X-ray imaging device an X-ray inspection on a hand carried baggage of a passenger and on a liquid product comprised of a container holding a liquid while the liquid product remains outside the baggage, the X-ray inspection generating X-ray image data of the hand carried baggage and X-ray image data of the liquid product, the liquid product having been removed from the hand carried baggage by the passenger prior to performing the X-ray inspection; b) processing the X-ray image data of the hand carried baggage to render an image of the hand carried baggage on a display to assist an operator in determining if the baggage contains illegal objects; c) processing with a computer the X-ray image data of the liquid product, the computer being programmed to: i) derive one or more characteristics of the container holding the liquid and path length information based at least in part on the X-ray image data of the liquid product, the path length information conveying a distance travelled by an X-ray through the liquid held in the container; ii) determine if the liquid held in the container is a security threat at least in part by using the derived path length information and one or more characteristics of the container holding the liquid to derive a parameter associated with the liquid held in the container. a) performing with a same X-ray imaging device an X-ray inspection on a hand carried baggage of a passenger and on a liquid product comprised of a container holding a liquid while the liquid product remains outside the baggage, the X-ray inspection generating X-ray image data of the hand carried baggage and X-ray image data of the liquid product, the liquid product having been removed from the hand carried baggage by the passenger prior to performing the X-ray inspection; b) processing the X-ray image data of the hand carried baggage to render an image of the hand carried baggage on a display to assist an operator in determining if the baggage contains illegal objects; c) processing with a computer the X-ray image data of the liquid product, the computer being programmed to: i) derive one or more characteristics of the container holding the liquid and path length information based at least in part on the X-ray image data of the liquid product, the path length information conveying a distance travelled by an X-ray through the liquid held in the container; ii) determine if the liquid held in the container is a security threat at least in part by using the derived path length information and one or more characteristics of the container holding the liquid to derive a parameter associated with the liquid held in the container. i) derive one or more characteristics of the container holding the liquid and path length information based at least in part on the X-ray image data of the liquid product, the path length information conveying a distance travelled by an X-ray through the liquid held in the container; ii) determine if the liquid held in the container is a security threat at least in part by using the derived path length information and one or more characteristics of the container holding the liquid to derive a parameter associated with the liquid held in the container.