Conversion efficiency of the CsI∶Tl crystal excited by X-ray

The X-ray conversion material in radiophotography system plays a very important role. Its efficiency is a crucial factor to improve the system QDE(quantum detection efficiency). The luminescent efficiency of CsI∶Tl crystal excited by Xray is analyzed in detail and the efficiency formula of the system adopting CCD camera,CsI∶Tl crystal is derived. The formula shows that the output of such a radiophotography system is proportional to the irradiation flux of incident X-ray. The QDE of such a system can be easily improved by changing the CsI∶Tl crystal thickness. Some experimental data obtained from a 30MeV electron linear accelerator are given to prove the linear relationship．