X-ray security inspection machine (10) comprising an X-ray tunnel (40); a
conveyor means (50) for conveying an article through the tunnel; an X-ray
source for irradiating the article; and an X-ray detection means for
detecting X-rays transmitted through the article. In one aspect, the
detection means comprises a photodetector array module (20) actuatable
between a first stowed configuration and a second deployed configuration.
In a second aspect, the detection means comprises a first unit having a
first photodetector array (22); and a second unit, having a second
photodetector array (24), offset with respect to the first unit. The
units are moveable relative to one another between a first arrangement
where the arrays overlap to a first degree and a second arrangement where
they overlap to a second, lower degree; preferably zero. Also, a conveyor
belt-tracking device (100) comprising a guide frame (104) to receive the
conveyor belt (116) and substantially to restrict its motion to a
predetermined direction.