1. A method of producing a double-doped scintillation crystal, comprising steps of:(A) growing a double-doped single crystal boule by Czochralski method, wherein said double-doped single crystal boule has a diameter of 70 mm and a length of 200 mm, said double-doped single crystal boule is a single crystal boule having general formula (I) or (II), and tetravalent cerium (Ce4+) become trivalent cerium (Ce3+) by charge compensation,
in the general formula (I) and (II), x is 0.003, y is more than 0.001 to less than 0.1, and z is equal to or greater than 0.05 to less than 1.898; and
(B) performing a thermal annealing process by placing the double-doped single crystal boule in a furnace, so as to form said double-doped scintillation crystal boule, wherein said thermal annealing process comprises:
a heating step, wherein the double-doped single crystal boule is heated from a room temperature to a temperature of 1400° C. 1600° C. in 480 minutes (mins)600 mins;
a temperature-sustaining step, wherein said temperature is maintained at 1400° C. 1600° C. for 50 hours (hrs)200 hrs and
a cooling step, wherein said double-doped single crystal boule is cooled down from 1400° C.1600° C. to a room temperature in 480 mins 720 mins.