Silicon CCD:s are used for X-ray imaging in fields as dentistry and ma
terials testing. Due to the low X-ray absorption in silicon the CCD is
generally coated with a scintillating layer. In order to evaluate the
response for different combinations of scintillator material, scintil
lator geometry and detector we have developed a simulation program. Th
e program calculates the signal to noise ratio and spatial resolution
based on both the signal from the scintillating layer and the signal f
rom direct detection of Xrays in the detector. Results obtained with t
his program indicate that the signal to noise ratio in the system is o
ptimized by using a scintillator with high X-ray absorption and high l
ight output while minimizing the signal from direct detection in the C
CD. The spatial resolution can be increased by defining pixels in the
scintillator.