After exposure the stored image is read-out using red He-Ne laser light. The laser light induces PSL in the phosphor which in turn emits characteristic blue light, the intensity of which is proportional to the number of absorbed incident X-ray photons. The luminescence is detected by a photomultiplier tube and then converted to a digital signal.
The raw spiral image is then corrected against a calibration image and converted
to a Cartesian coordinate system. A separate calibration image is set up for each
plate using a flood field from an 
radioactive source and is used to
correct all images recorded by the plates. After read out the plate is erased
more thoroughly by Tungsten lamps.