Intra-lumen polyp detection

An apparatus for detecting clinically-relevant features of a gastrointestinal (GI) tract of a subject, comprising:

• a capsule with a capsule housing, said capsule adapted to be swallowed by a subject, said capsule comprising:
• at least one radiation source emitting X-ray or gamma radiation;
• at least one radiation detector configured detect in a first energy window collimated X-ray fluorescence radiation from the X-ray contrast agent composition excited by the emitted radiation, and to detect a second energy window Compton-backscattered radiation from the X-ray contrast agent and the wall of the GI tract produced in response to the emitted radiation;
• and
• at least two electrodes spaced on the capsule, with at least one electrode emitting electromagnetic pulses and at least one other electrode detecting a response signal responsive to the emitted electromagnetic pulses;
• the apparatus further comprising a control unit configured to determine from the response signal a change in a relative position of the capsule in the GI tract and to derive from the Compton-backscattered radiation and the X-ray fluorescence radiation information regarding a clinically-relevant feature.