Digital radiography(DR) systems have recently been developed and are substituting for conventional X-ray film. CsI scintillation screen coupled to amorphous silicon photodiode is one of the most promising systems of digital radiography. The CsI scintillation crystals, whose unit size is matched with that of the photodiode (~100 ㎛), were developed and their performance was measured.
The light collection efficiency of the newly developed type, simply called ideal column in this thesis, was calculated by Monte Carlo method. The X-ray energy deposition was simulated by MCNP code and the light collection efficiency for a certain position in scintillation layer was calculated with DETECT code. As a result, the ideal column type, in comparison with conventional CsI structure, was more efficient for light yield.
The performances of three kinds of structured CsI(Na) - ideal column, poly-crystal and thin column type - were measured. The ideal column type of CsI(Na) showed higher light yield than other structures when exposed to X-ray. The resolution of this type was also better than that of poly-crystal type but could not be compared with that of thin column type emitting very small light. The light transmission and confinement of ideal column were superior to those of other structure types.
