Back to results
US 4,536,436 AGranted
Radiographic image conversion screens
AssigneeKasei Optonix, Ltd.
InventorsHidehiko Maeoka, Etsuo Shimizu, Yujiro Suzuki, Keiji Shimiya, Norio Miura
Life of this patent
Estimating the term…
Abstract
A radiographic image conversion screen comprises a support, a first fluorescent layer formed on the support and consisting essentially of a blue emitting phosphor and a second fluorescent layer formed on the first fluorescent layer and consisting essentially of a green emitting rare earth phosphor.
Claims8
A radiographic image conversion screen, having a speed and/or an image quality at least equal to that of a conventional radiographic image conversion screen which has only a green emitting rare earth phosphor layer, consisting essentially of:
- (a) a support;
- (b) a first fluorescent layer formed on said support and consisting essentially of a blue emitting phosphor which is selected from the group consisting of:
- (I) a yttrium or yttrium-gadolinium oxysulfide phosphor represented by the formula:
- (Y.sub.1-c-d-e, Gd.sub.c, Tb.sub.d, Tm.sub.e).sub.2 O.sub.2 S
- where c, d and e are numbers within the ranges of 0.ltoreq.c.ltoreq.0.60, 0.0005.ltoreq.d.ltoreq.0.02 and 0.ltoreq.e.ltoreq.0.01, respectively;
- and
- (II) a rare earth oxyhalide phosphor represented by the formula:
- (Ln'.sub.1-x-y-z, Tb.sub.x, Tm.sub.y, Yb.sub.z)OX
- where Ln' is at least one element selected from the group consisting of lanthanum and gadolinium, X is at least one element selected from the group consisting of chlorine and bromine, and x, y and z are numbers within the ranges of 0.ltoreq.x.ltoreq.0.01, 0.ltoreq.y.ltoreq.0.01, 0.ltoreq.z.ltoreq.0.005 and 0.ltoreq.x+y;
- and (c) a second fluorescent layer formed on said first fluorescent layer and consisting essentially of a green emitting rare earth oxysulfide phosphor represented by the formula:
- (Ln.sub.1-a-b, Tb.sub.a, Tm.sub.b).sub.2 O.sub.2 S
- where Ln is at least one element selected from the group consisting of lanthanum, gadolinium and lutetium, and a and b are numbers within the ranges of 0.0005.ltoreq.a.ltoreq.0.09 and 0.ltoreq.b.ltoreq.0.01, respectively, or the formula:
- (Y.sub.1-i-a-b, Ln.sub.i, Tb.sub.a, Tm.sub.b).sub.2 O.sub.2 S
- where Ln is at least one element selected from the group consisting of lanthanum, gadolinium and lutetium, and i, a and b are numbers within the ranges of 0.65.ltoreq.i.ltoreq.0.95, 0.0005.ltoreq.a.ltoreq.0.09 and 0.ltoreq.b.ltoreq.0.01, respectively.
11 more elements
A method of obtaining a radiographic image of a subject with a radiographic apparatus, comprising:
- obtaining a radiographic image of said subject with said radiographic device in which an image conversion screen, having a speed and/or an image quality at least equal to that of a conventional radiographic image conversion screen which has only a green emitting rare earth phosphor layer, consists essentially of:
- (a) a support;
- (b) a first fluorescent layer formed on said support and consisting essentially of a blue emitting phosphor which is selected from the group consisting of:
- (I) a yttrium or yttrium-gadolinium oxysulfide phosphor represented by the formula:
- (Y.sub.1-c-d-e, Gd.sub.c, Tb.sub.d, Tm.sub.e).sub.2 O.sub.2 S
- where c, d and e are numbers within the ranges of 0.ltoreq.c.ltoreq.0.60, 0.0005.ltoreq.d.ltoreq.0.02 and 0.ltoreq.e.ltoreq.0.01, respectively;
- and
- (II) a rare earth oxyhalide phosphor represented by the formula:
- (Ln'.sub.1-x-y-z, Tb.sub.x, Tm.sub.y, Yb.sub.z)OX
- where Ln' is at least one element selected from the group consisting of lanthanum and gadolinium, X is at least one element selected from the group consisting of chlorine and bromine, and x, y and z are numbers within the ranges of 0.ltoreq.x.ltoreq.0.01, 0.ltoreq.y.ltoreq.0.01, 0.ltoreq.z.ltoreq.0.005 and 0.ltoreq.x+y;
- and (c) a second fluorescent layer formed on said first fluorescent layer and consisting essentially of a green emitting rare earth oxysulfide phosphor represented by the formula:
- (Ln.sub.1-a-b, Tb.sub.a, Tm.sub.b).sub.2 O.sub.2 S
- where Ln is at least one element selected from the group consisting of lanthanum, gadolinium and lutetium, and a and b are numbers within the ranges of 0.0005.ltoreq.a.ltoreq.0.09 and 0.ltoreq.b.ltoreq.0.01, respectively, or the formula:
- (Y.sub.1-i-a-b, Ln.sub.i, Tb.sub.a, Tm.sub.b).sub.2 O.sub.2 S
- where Ln is at least one element selected from the group consisting of lanthanum, gadolinium and lutetium, and i, a and b are numbers within the ranges of 0.65.ltoreq.i.ltoreq.0.95, 0.0005.ltoreq.a.ltoreq.0.09 and 0.ltoreq.b.ltoreq.0.01, respectively.
12 more elements
Dependencies are inferred from the claim text.