U.S. Pat. No. 3,859,527 describes a method for recording and reproducing a high-energy radiation image using a panel for storing a radiation image comprising a stimulable phosphor which emits light when stimulated with visible or infrared radiations after exposure to such radiation (wherein high-energy radiation means an electromagnetic wave or corpuscular radiation such as X-rays, .alpha.-rays, .beta.-rays, gamma-rays, neutrons, ultraviolet rays, or the like).
U.S. Pat. No. 4,258,264 describes a method and apparatus for reproducing a radiation image by stimulating a storing phosphor with stimulating rays, the wavelengths of which are in the range from 600 to 700 nm, and detecting the stimulated light by means of a light detector, the detected light being in the range from 300 to 500 nm.
European patent application Ser. No. 159,726 describes an alkali earth metal halide phosphor activated with divalent europium having the formula: EQU M"X.sub.2 .multidot.aM"X'.sub.2 .multidot.bA:xEu.sup.2+
wherein M" is at least one alkali earth metal selected within the group consisting of Ba, Sr and Ca; both X and X' are at least a halogen selected within the group consisting of Cl, Br and I, X being different from X'; A is at least one oxide selected within the group consisting of SiO.sub.2 and P.sub.2 O.sub.5 ; a, b and x are numbers respectively satisfying the conditions 0.1.ltoreq.a.ltoreq.10; 10.sup.-4 .ltoreq.b.ltoreq.0.2 and 0&lt;x.ltoreq.0.2. In the above mentioned patent application there are also described a method for recording and reproducing a radiation image using said phosphor and a radiation image storing panel using such phosphor. The radiations stimulating said phosphor preferably have a wavelength in the range from 500 to 800 nm.
European patent application Ser. No. 107,192 describes a method for recording and reproducing a radiation image comprising the steps of (i) causing a stimulable phosphor to absorb radiation passing through an object, (ii) exposing said stimulable phosphor to an electromagnetic wave having a wavelength in the range from 450 to 800 nm to release the stored radiation energy as fluorescent light and (iii) detecting said fluorescent light, wherein said stimulable phosphor is a divalent europium activated complex halide having the formula: EQU M''FX.multidot.aM'X'.multidot.bM'''X".sub.2 .multidot.cM'''X'''.sub.3 .multidot.xA:yEu.sup.2+
wherein M'' is at least an alkali earth metal selected within the group consisting of Ba, Sr and Ca; M' is am alkali metal selected within the group consisting of Li, Na, K, Rb and Cs; M''' is at least a trivalent metal selected within the group consisting of Al, Ga, In and Tl; A is at least a metal oxide; X is at least a halogen selected within the group consisting of Cl, Br and I; each of X', X'' and X''' are at least a halogen selected within the group consisting of Cl, Br and I; a, b and c are numbers respectively satisfying the conditions 0.ltoreq.a.ltoreq.2; 0.ltoreq.b.ltoreq.0.01; 0.ltoreq.c.ltoreq.0.01 and a+b+c.gtoreq.10.sup.-6 ; x and y are numbers respectively satisfying the conditions 0&lt;x.ltoreq.0.5 and 0&lt;y.ltoreq.0.2. Such patent application describes also a radiation image storing panel used for such a method.
The phosphors described in the above cited European patent applications Ser. No. 159,726 and 107,192 give the best results, with respect to the emission efficiency, when they are stimulated with radiation having a wavelength in the range from 600 to 700 nm, in particular when they are stimulated with a He-Ne 633 nm laser beam. Such phosphors do not give such good results when they are stimulated with a radiation having a wavelength lower than 600 nm.
European patent application Ser. No. 111,893 describes a method for recording and reproducing a radiation image comprising the steps of (i) causing a radiation image storing panel to absorb a radiation passing through an object, such a panel containing a divalent europium activated barium fluorochloride phosphor, (ii) exposing said panel to an electromagnetic wave having a wavelength in the range from 400 to 550 nm to release the stored radiation energy as fluorescent light and (iii) detecting said fluorescent light.