CA1175647A - Fluorescent compositions, x-ray intensifying screens, and processes for making same - Google Patents
Fluorescent compositions, x-ray intensifying screens, and processes for making sameInfo
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- CA1175647A CA1175647A CA000393825A CA393825A CA1175647A CA 1175647 A CA1175647 A CA 1175647A CA 000393825 A CA000393825 A CA 000393825A CA 393825 A CA393825 A CA 393825A CA 1175647 A CA1175647 A CA 1175647A
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- phosphor
- percent
- index
- refraction
- weight
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- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21K—TECHNIQUES FOR HANDLING PARTICLES OR IONISING RADIATION NOT OTHERWISE PROVIDED FOR; IRRADIATION DEVICES; GAMMA RAY OR X-RAY MICROSCOPES
- G21K4/00—Conversion screens for the conversion of the spatial distribution of X-rays or particle radiation into visible images, e.g. fluoroscopic screens
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
- C09K11/02—Use of particular materials as binders, particle coatings or suspension media therefor
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- General Engineering & Computer Science (AREA)
- High Energy & Nuclear Physics (AREA)
- Conversion Of X-Rays Into Visible Images (AREA)
- Radiography Using Non-Light Waves (AREA)
- Luminescent Compositions (AREA)
- Silver Salt Photography Or Processing Solution Therefor (AREA)
Abstract
Abstract of the Disclosure An x-ray intensifying screen comprises a support having thereon a fluorescent composition comprising:
a) from 50 to 90 percent by weight of a substantially isotropic phosphor which 15 excited by x-rays and substantially transparent to light emitted by said phosphor; and b) from 13 to 50 percent by weight of a polymer having an index of refraction within .02 of the index of refraction of said phosphor over at least 80 percent of the omission spectrum of said phosphor, said support having an index of refraction up to or equal to 0.05 units higher than the index of refraction of said phosphor and having a reflection optical density of at least 1.7 to light emitted by said phosphor.
The screen is highly transparent, and further exhibits improved contrast and resolution. A preferred fluorescent composition useful in the x-ray intensifying screen comprises:
a) from 50 to 93 percent by weight of a substantially isotropic phosphor which is excited by x-rays and substantially transparent to light emitted by said phosphor; and b) from 10 to 50 percent by weight of a polymer having an index of refraction within .02 of the index of refraction of said phosphor over at least 80 percent of the emission spectrum of said phosphor, said polymer com-prising:
i) from 5 to 99 mole percent of recurring units having the formula:
wherein:
R1 is H or alkyl; and R2 is alkyl, cycloalkyl, aryl, aralkyl or aryl substituted with alkyl, alkoxy or heterocyclic; and ii) from 1 to 95 mole percent of recurring units having the formula:
wherein:
Ar is arylene;
R1 is H or alkyl;
R3 is H, alkyl, aryl, or aralkyl; and R4 is H, alkyl, alkoxy, amino, halogen, sulfide, sulfoxide, sulfonate or heterocyclic.
a) from 50 to 90 percent by weight of a substantially isotropic phosphor which 15 excited by x-rays and substantially transparent to light emitted by said phosphor; and b) from 13 to 50 percent by weight of a polymer having an index of refraction within .02 of the index of refraction of said phosphor over at least 80 percent of the omission spectrum of said phosphor, said support having an index of refraction up to or equal to 0.05 units higher than the index of refraction of said phosphor and having a reflection optical density of at least 1.7 to light emitted by said phosphor.
The screen is highly transparent, and further exhibits improved contrast and resolution. A preferred fluorescent composition useful in the x-ray intensifying screen comprises:
a) from 50 to 93 percent by weight of a substantially isotropic phosphor which is excited by x-rays and substantially transparent to light emitted by said phosphor; and b) from 10 to 50 percent by weight of a polymer having an index of refraction within .02 of the index of refraction of said phosphor over at least 80 percent of the emission spectrum of said phosphor, said polymer com-prising:
i) from 5 to 99 mole percent of recurring units having the formula:
wherein:
R1 is H or alkyl; and R2 is alkyl, cycloalkyl, aryl, aralkyl or aryl substituted with alkyl, alkoxy or heterocyclic; and ii) from 1 to 95 mole percent of recurring units having the formula:
wherein:
Ar is arylene;
R1 is H or alkyl;
R3 is H, alkyl, aryl, or aralkyl; and R4 is H, alkyl, alkoxy, amino, halogen, sulfide, sulfoxide, sulfonate or heterocyclic.
Description
v~
FLUORESCENT COM~OSITIONS, X-RAY INTENSIFYING
SCREENS, AND PROCESSES FOR MAKING SAME
.
BACKGROUND OF THE INVENTION
Field of the Invention This invention relates to transparent x-ray intensifying screens and processes for making x-ray intensifying screens for use in radiography, and to fluorescent compositions comprising anlsotropic phosphor transparent to x-rays and a polymeric binder.
10 Description Relative to the Prior Art Transparent x-ray screens comprising alkali halide, alkaline earth halide, meta] sulfide, and metal selenide phosphors have been prepared by various methods. These transparent screens have been shown to be desirable, because they make moxe efficient use of impinging x-ray radiation than thick conventional scatter-ing screens, which ~<waste a material amount of the radiation in diffusion of the light emitted near the back of the screen and internal absorption. Thick transparent screens, having a decreased number of reflections permit this light to reach the 20 front surface of the screen with minimal deflection and to form a sharper image on the photographic film in contact with the screen~ A greater proportion of the x ray energy, absorbed by the phosphor and converted to light, is utilized in producing images without loss of sharpness.
Thin transparent screens, prepared by vapor-deposition and containing only a phosphor, have also been made and exhibit lower speeds than scattering screens with equal phosphor coverage. Further, lacking a protective binder, these transparent screens are fragile and highly susceptible to 30 physical damage~ Thicker screens have been made by hot pressing but other defects in the manufacture of these large plates render them expensive to prepare.
~$~
U.S. Patent No 3,023,313, issued February 27, 1962 to De La Mater et al discloses the use of a polymeric binder with a refractive index as close to -that of an alkali metal halide phosphor as possible in order to produce x-ray intensifying screens with improved speed. However, because of substantial differences between the refractive index of selected binders and the refractive index of the phosphor, reflecting pigments must be added to the mixture to prevent blurring of the image and improve resolution. Thus, these screens are not truly transparent to light, and some decrease in utilization of absorbed x-rays is observed. The screens of De La Mater comprise a support preferably having a highly reflective base coating.
Swank, Applied Optics, 12, 1865-1870 ~1973) describes the theoretical calculation of modulation transfer function (MTF), related to resolving power, of x-ray intensifying screens comprising transparent phosphors and a black backing.
Swank discloses that although the Ml'F :is enhanced when a black backing is used, 50% of the exposing radiation is absorbed by the backing. Thus, the speed of the x--ray intensifying screen is reduced.
Gasper, J. Opt. Soc. Am., 63, 71~-720 (1973) describes the computation of theoretical efficiencies and MTFs of various screen-receiver systems, and reports that if a dark antihalation undercoat is applied to the back surface of a transparent screen, the MTF is only slightly improved If, on the other hand, the back surface is made perfectly reflecting, there is degradation of~MTF, but the efficiency of the screen is advantageously doubled, as is shown in Figure 8 of Gasper.
Experimental verification of the Gasper calculations is provided by measuring the MTF of a trans-pa~ent hot-pressed zinc sulfide sc~een coated with a dyed gelatin undercoat. Excellent agreement was found between ~1 '7 the measured and computed MT~s. Gasper concludes that attempts to improve the MTF of a transparent screen res~lt in an undesirable loss o~ efficiency. Given a choice between slight increases in MTF coupled with undesirable losses in efficiency (with an absorbing under-coat), and great increases ln efficiency coupled with only slightly lower MTFs (reflective undercoat), the high efficiency screen with a reflectlve undercoat is clearly preferred by Gasper.
It is seen that transparent x-ray intensi-fying screens providing high resolution, while maintàining speed and efficiency, and which are resistant to physical damage and are easily and economically manu-factured, are extremely desirable.
.
I
SUMMA~Y OF THE INVENTION
_ _ .
An x-ray intensifying screen according to this invention comprises a support having thereon a fluorescent composition comprising:.
a) from 50 to 90 percent by weight of a substantially isotropic phosphor which is excited by x-rays and substantially transpa.rent to light emitted by said p~osphor; and b) from 10 to 50 percent by weig~t of a polymer havi~g an index of refraction within .02 of the index of refraction of said phosphor over at least 80 percent of the emission spectrum of said phosphor;
said support having an index of refraction equal to or up to 0.05 units hI~her than the index of refraction of said phosphor 15 and having a reflection optical, density of at least 1.7 to light emitted by said phosphor. Using this x-ray intensifying screen~ high resolution andhigh contrast are obtained, while maintaining high speed, efficieney and resistance to physical damage. ~urther, the screens can be easily manufactured and 20 do not require the addition of reflection pigments to prevent image blurring.
It has also been found that a particularly advantageous fluorescent composition eomprises:
a) from 50 to 90 percent by weight of a substantially isotropic phosphor which is exeited by x-rays and substantially transparent to light emitted by said phosphor; and b) from 10 to 50 percent by weight of a polymer having an index of refraction within .02 of the index of refraction of said phosphor over at least 80 percent of the emission spectrum of said phosphor, said polymer eomprising:
i) from 5 to 99 mole pe~eent of recurring units having the formuIa:
: 35 ~' (CH2 C) C=O
wherein:.
R is H or alkyl; and R is alkyl, cycloalkyl, aryl, aralkyl or aryl substituted with alkyl, alkoxy, or heterocyclic;
and ii) from l to 95 mole percent of recurring units having the the for~ula::
,R
( H2 C~
C=o S-CH-R
i Ar-R
wherein Ar is arylene;
R is H or alkyl;
R3 is H, alkyl, aryl, or aralkyl; and R4 is H, alkyl, alkoxy, amino, halogen, sulfide, sulfoxide, sulfonate or heterocyclic.
In a further embodiment of the invention, a process -for making an x-ray intensifying screen comprises the steps of:
a~ coating a mixture comprising:.
i) from 50 to 90 percent by weight of a substan-tially isotropi~ phosphor which is excited by x-rays and substantially transparent to light emitted by said phosphor; and ii~ from lO to 50 percent by weight of at least one copolymerizable monomer or mixture of monome~s, said monomer or mixture o;E monomers, , when polymerized, having an index of refxaction within .02 of the in,dex of refraction of said phosphor over a-t least 80 percent the emission spectrum of said phosphor, on a support having an index of refraction equal to or up to 0.05 units higher than the index of refraction of said phosphor and having a reflection optical, density of a-t least 1.7 to light emitted by said phosphor; and b) polymerizing said mixture coated on said support to produce a polymer comprising recurring units of said monomer or monomer mixture.
DETAILED DESCRIPTION OF'THE'PREFERRED'EMBODIMENTS
A novel x-ray intensifying screen comprises a support having thereon a fluorescent composition comprising:
a) from 50 to 90 percent by weight of a substantially isotropic phosphor which is excited by x-rays and substantially transparent to light emitted by said phosphor; and b) from 10 to 50 percent by weight of a polymer having an index of refraction within .02 of the index of refraction of said phosphor over at least ~0 percent of the emission spectrum oE said phosphor;
said support having an index of refraction equal to or up to 0.05 units higher than the index of refraction of said phosphor and having a reflection optical density of at least 1.7 to light
FLUORESCENT COM~OSITIONS, X-RAY INTENSIFYING
SCREENS, AND PROCESSES FOR MAKING SAME
.
BACKGROUND OF THE INVENTION
Field of the Invention This invention relates to transparent x-ray intensifying screens and processes for making x-ray intensifying screens for use in radiography, and to fluorescent compositions comprising anlsotropic phosphor transparent to x-rays and a polymeric binder.
10 Description Relative to the Prior Art Transparent x-ray screens comprising alkali halide, alkaline earth halide, meta] sulfide, and metal selenide phosphors have been prepared by various methods. These transparent screens have been shown to be desirable, because they make moxe efficient use of impinging x-ray radiation than thick conventional scatter-ing screens, which ~<waste a material amount of the radiation in diffusion of the light emitted near the back of the screen and internal absorption. Thick transparent screens, having a decreased number of reflections permit this light to reach the 20 front surface of the screen with minimal deflection and to form a sharper image on the photographic film in contact with the screen~ A greater proportion of the x ray energy, absorbed by the phosphor and converted to light, is utilized in producing images without loss of sharpness.
Thin transparent screens, prepared by vapor-deposition and containing only a phosphor, have also been made and exhibit lower speeds than scattering screens with equal phosphor coverage. Further, lacking a protective binder, these transparent screens are fragile and highly susceptible to 30 physical damage~ Thicker screens have been made by hot pressing but other defects in the manufacture of these large plates render them expensive to prepare.
~$~
U.S. Patent No 3,023,313, issued February 27, 1962 to De La Mater et al discloses the use of a polymeric binder with a refractive index as close to -that of an alkali metal halide phosphor as possible in order to produce x-ray intensifying screens with improved speed. However, because of substantial differences between the refractive index of selected binders and the refractive index of the phosphor, reflecting pigments must be added to the mixture to prevent blurring of the image and improve resolution. Thus, these screens are not truly transparent to light, and some decrease in utilization of absorbed x-rays is observed. The screens of De La Mater comprise a support preferably having a highly reflective base coating.
Swank, Applied Optics, 12, 1865-1870 ~1973) describes the theoretical calculation of modulation transfer function (MTF), related to resolving power, of x-ray intensifying screens comprising transparent phosphors and a black backing.
Swank discloses that although the Ml'F :is enhanced when a black backing is used, 50% of the exposing radiation is absorbed by the backing. Thus, the speed of the x--ray intensifying screen is reduced.
Gasper, J. Opt. Soc. Am., 63, 71~-720 (1973) describes the computation of theoretical efficiencies and MTFs of various screen-receiver systems, and reports that if a dark antihalation undercoat is applied to the back surface of a transparent screen, the MTF is only slightly improved If, on the other hand, the back surface is made perfectly reflecting, there is degradation of~MTF, but the efficiency of the screen is advantageously doubled, as is shown in Figure 8 of Gasper.
Experimental verification of the Gasper calculations is provided by measuring the MTF of a trans-pa~ent hot-pressed zinc sulfide sc~een coated with a dyed gelatin undercoat. Excellent agreement was found between ~1 '7 the measured and computed MT~s. Gasper concludes that attempts to improve the MTF of a transparent screen res~lt in an undesirable loss o~ efficiency. Given a choice between slight increases in MTF coupled with undesirable losses in efficiency (with an absorbing under-coat), and great increases ln efficiency coupled with only slightly lower MTFs (reflective undercoat), the high efficiency screen with a reflectlve undercoat is clearly preferred by Gasper.
It is seen that transparent x-ray intensi-fying screens providing high resolution, while maintàining speed and efficiency, and which are resistant to physical damage and are easily and economically manu-factured, are extremely desirable.
.
I
SUMMA~Y OF THE INVENTION
_ _ .
An x-ray intensifying screen according to this invention comprises a support having thereon a fluorescent composition comprising:.
a) from 50 to 90 percent by weight of a substantially isotropic phosphor which is excited by x-rays and substantially transpa.rent to light emitted by said p~osphor; and b) from 10 to 50 percent by weig~t of a polymer havi~g an index of refraction within .02 of the index of refraction of said phosphor over at least 80 percent of the emission spectrum of said phosphor;
said support having an index of refraction equal to or up to 0.05 units hI~her than the index of refraction of said phosphor 15 and having a reflection optical, density of at least 1.7 to light emitted by said phosphor. Using this x-ray intensifying screen~ high resolution andhigh contrast are obtained, while maintaining high speed, efficieney and resistance to physical damage. ~urther, the screens can be easily manufactured and 20 do not require the addition of reflection pigments to prevent image blurring.
It has also been found that a particularly advantageous fluorescent composition eomprises:
a) from 50 to 90 percent by weight of a substantially isotropic phosphor which is exeited by x-rays and substantially transparent to light emitted by said phosphor; and b) from 10 to 50 percent by weight of a polymer having an index of refraction within .02 of the index of refraction of said phosphor over at least 80 percent of the emission spectrum of said phosphor, said polymer eomprising:
i) from 5 to 99 mole pe~eent of recurring units having the formuIa:
: 35 ~' (CH2 C) C=O
wherein:.
R is H or alkyl; and R is alkyl, cycloalkyl, aryl, aralkyl or aryl substituted with alkyl, alkoxy, or heterocyclic;
and ii) from l to 95 mole percent of recurring units having the the for~ula::
,R
( H2 C~
C=o S-CH-R
i Ar-R
wherein Ar is arylene;
R is H or alkyl;
R3 is H, alkyl, aryl, or aralkyl; and R4 is H, alkyl, alkoxy, amino, halogen, sulfide, sulfoxide, sulfonate or heterocyclic.
In a further embodiment of the invention, a process -for making an x-ray intensifying screen comprises the steps of:
a~ coating a mixture comprising:.
i) from 50 to 90 percent by weight of a substan-tially isotropi~ phosphor which is excited by x-rays and substantially transparent to light emitted by said phosphor; and ii~ from lO to 50 percent by weight of at least one copolymerizable monomer or mixture of monome~s, said monomer or mixture o;E monomers, , when polymerized, having an index of refxaction within .02 of the in,dex of refraction of said phosphor over a-t least 80 percent the emission spectrum of said phosphor, on a support having an index of refraction equal to or up to 0.05 units higher than the index of refraction of said phosphor and having a reflection optical, density of a-t least 1.7 to light emitted by said phosphor; and b) polymerizing said mixture coated on said support to produce a polymer comprising recurring units of said monomer or monomer mixture.
DETAILED DESCRIPTION OF'THE'PREFERRED'EMBODIMENTS
A novel x-ray intensifying screen comprises a support having thereon a fluorescent composition comprising:
a) from 50 to 90 percent by weight of a substantially isotropic phosphor which is excited by x-rays and substantially transparent to light emitted by said phosphor; and b) from 10 to 50 percent by weight of a polymer having an index of refraction within .02 of the index of refraction of said phosphor over at least ~0 percent of the emission spectrum oE said phosphor;
said support having an index of refraction equal to or up to 0.05 units higher than the index of refraction of said phosphor and having a reflection optical density of at least 1.7 to light
2~ emitted by said phosphor.
Any substantially isotropic phosphor which is excited by x~-rays and substantially transparent to the light emitted by the excited phosphor is usefuI in preparing the fluorescent composition. The term substantially iso-tropic phosphor is 30 used herein to mean a crystalline phosphor having substantially the same optical properties in all ddrections of the crystal~
and that the crystalline phosphor is substantially free from defects! such as cracks and inclusion,s, which cause scattering of light. Useful phosphors include activated alkali metal halides, such as KCl:Sb, CsBr:Tl, KI:Tl, KBr:Tlt KCl:Tl, RbCl:Tl, RbBr:Tl and RbI:Tl; alkaline earth halides such as BaF2 and Ba~Cl; activated alkaline earth halides such as Ca~2:Eu, SrC12:Sm, SrF2:Eu, BaFCl:Sr, Eu, BaFCl:Eu and SrF2:Sm; activated metal silicates such as BaSiO3:Eu, CaSiO3:Mn and Zn2SiO~:Mn; mixed metal fluorides such as KCdF3:Mn and CsCdF3:Mn; metal sulfates such as lanthanide-activated metal sulfates such as BaSO4:Sr, Eu, SrSO4:Eu, BaSO4:Eu, ZnSO4:Mn and Cs3SO~:Ce; metal gallates such as ZnGa2O4:Mn; and phosphates such as lanthanide-activated phosphates such as Ba2P4O7:Eu and Ca3(PO4)2:Ce examples of phosphors are described in U.S. Patent Nos.
4,100,101, 2,303,g63, 3,163,610, 3~163,603 and 3,506,584 and in R.C. Pastor et al, Mat. Res. Bull., 15 469-475 (1980). Typical transparent phosphors include RbI:Tl;
KI:Tl; BaFCl:Sr, Eu; BaSO4:Sr, Eu; CsCdF3Mn; BaF2;
KCdF3:Mn; and SrF2. Preferred phosphors are RbI:Tl;
KI:Tl~; BaFCl:Sr, Eu; CsCdF3:Mn; BaSO4:Sr, Eu; and BaSO4:Pb.
The above-described phosphors are prepared by any conventional method for preparing isotropic phos-phors, such as by introducing the anions and cations which form the phosphor into a reaction solution,main-taining an excess of up to 1 molar of an anion or cation throughout the reaction mixture, preventing local excesses of cations or anions, and thus slowly growing crystals of the phosphor to at least 0.5 micron, as described in U.S. Patent No. 3,668,1l~2 issued June 6, 1972 to Luckey.
Other methods for preparing isotropic phosphors which are excited by x-rays and substantially transparent to the emitted light, include precipitation at elevated temperatures and super-atmospheric pressures described in ~uthruff, U.S. Patent No. 2,285,464; precipitation followed by firing, fusion, and grinding to the desired particle size; and ignition in the presence of a flux~
The method of U.S. Patent No. 3,668,142 is the preferred method for preparing the isotropic phosphors.
-7a-These screens can be modlfied so that they are useful in the apparatus and methods for producing images that are described in U.S.3,8599527~ U.S~
4,346,295 and U.S. 4,236,078. In this modification an essentially isotropic storage phosphor is eoated in a binder on a support that has the characteristics described below. The phosphor is excited by a pat-tern of radiation of a first wavelength. The phos-phor is then exposed to radia~ion of a second wave length which causes the said storage medium to emit a ~hird wavelength of radiation having an intensity pattern representative of ~he stored image. The binder used in making this screen matches the index of refraction of the phosphor at th~ second wave-length and the support for the screen is selected sothat it does not reflect the radiation at the second wavelength. The index of refraction of ~he binder at the third wavelength is preferably selected so that i~ does not match that of the phosphor and the sup-port of the screen may reflect the radiation at thethird wavelength. Thus, the radiation at the third wavelength, which is emitted when the phosphor is irradiated at the second wavelength, is not trapped by total internal reflection or by the support, but escapes from the screen and is efficiently collected by a photomultiplier tube with appropriate optics or by other photosensors which respond efficien~ly to the radiation at the third wavelength. Screens of this type are particularly useful for radiography and other applications in which a pattern of hi8h energy radiation is absorbed by the phosphor 9 then released by scanning the screen wlth a laser beam that has a wavelength equal to that where the index of refrac tion of the phosphor and binder are matched and where . ~
~7~
-7b-the support of the screen has minimum reflectance.
Ideally, the beam from the laser follows the path of the high energy radiation 60 that the resolution of the image from the screen i6 determined by ~he dimen-sions of the laser beam. The light released from thephosphor by the laser is collected by an appropriate photosensor, amplified, and the signal displayed on a cathode ray ~ube or recorded on an image recording medium to form the imageO Appropriate phosphors com-prise the barium alkaline earth metal fluorohalidesof U.S. 4,261,854 and U.S. 4,239,968, and other storage phosphors which have indices of refracti.on less than about 1.75 in the visible region of the spectrum.
, ~i ~ ne phosphor crystals are optionally activated to obta n the desired speed by any conventlonal method of activation. One method is the addition o~ a solution o~ a small amount (about .05 percent by weight) o~ the activating ion in a solvent, such as isopropanol 9 to a vigorously stirred solution of the lsotropic host in a solvent, such as water, at very low temperatures (-30 to ~20C), followed by collection of the precipitated activated phosphor.
The substantially isotropic phosphors Or the invention generally have crystalline morphologies which are cubic or substantially cubic. The substantially isotropic phosphors of the invention generally have crystal sizes in the range rrom about 1 to about 50 microns, with the size range from about 10 to about 20 micro~s bein~ preferred.
~ ne novel x-ray ~ntensifying screen includes an~ polymer having an index of refraction within .02 of the index of refraction of the phosphor over at least Bo percent of the emission spectrum.
The selection of the polymer for the novel x-ray intensifying screen is depenclent on the index of refract~on of the selected substantially isotropic phosphor at its emission wavelength. The index of 25 refraction of the phosphor is determined by measuring the transmission spectra of the phosphor mixed with a series of Cargille liquids~ as described in "~he Particle Atlas", McCrone, Dra~tz and Delly, Ann Arbor Science Publishers, Inc., 1967, and determining the 30 wavelength at ~nich the index of refraction of th~ phosphor and the liquid match. A phosphor dispersion curve is obtained by plotting the wavelengths o~ maximum transmission ror the series on the ~amily o~ Cargille dispersion curves publlshed in "The Particle Atlas" referred to above. The phosphor dispersion curve thus obtained is used directly to find the lndex of rerraction required for the polymer of the novel transparent x-ray intensi~ying screen.
l7~
~ he polymer havin~ the required index of rerrac-tion, i.e., an index of refraction within .02 of the refraction of the phosphor over at least 80 percent Or its emission spectrur,, comprises a single polymerized monomer, or the polymer comprises a mixture of two or more poly-merized copolymerizable monomers. Generally, the polymer comprises two copolymerizable polymerized monomers, one of which, when polymerized, provides a polymer o~ higher index of refraction than required, and one which~ when polymerized, provides a lower index of rerraction than required. The relative proportions of the two monomers are advusted to provide the required rerraction index.
Calculated formulations are verified by measuring the transmission curve ol a sample coating o~ the fluorescent composition of the novel intensifying screen on a spectro~
photometer. h wavelength of maximum transmission which is less ~han tha~ of the phosphor er.ission wavelen~th indicates that the refractive index of the polymeric b~nder is too low. A wavelength Or maximum transmission 2~ which is greater than that of the phosphor emission wave-leng~h indicates that the refractive index of the polymer is too high.
Morlomers which, when polymerized, provide an index of refraction higher than that o~ the phosphor selected generally ~rovide an index of refraction above 1.4 3 preferably in the range from 1.40 to 1.75. Examples of monomers which, when polymerized, provide an index of refraction higher than that of the pho~phor selected, and thus can be mixed with monomers having a lower index of refractlon to become useful herein, include S~
naphthyl carbinyl) thioacrylate, naphthyl acrylate, 1-bromo-2-nap~hylacrylate and naphthylmethacrylate. The pre~erred monomer is S-(l-naphthyl carbinyl)thioacrylate.
Monomers which, when polymerized, provide an index of re~raction lower than that of the pho~phor generally provide an index of refraction ranging from about 1.40 to about 1.75, preferably in the range from --10~
1.40 to 1.60. Examples of monomers which, when poly-merized, provide ~n index of refrackion lower than that Or the phosphor selected and thus are useful when mlxed with monomers having a higher index Or refraction~
include copolymerizable ethylenically unsaturated mono-mers such as acrylates and methacrylates such as methyl acrylate~ ethyl acrylate, propyl acrylate, bu~yl acrylate, butyl methacrylate and cyc]ohexyl methacrylate; vinyl ester~, amides, nitriles, ketones, halides, ethers, 13 olefins, and diolefins as exemplified by acrylonitrile, methacrylonitrile, styrene, ~-methyl ~tyrene, acrylamide~
methacrylamide, vinyl chloride, methyl vinyl ketone, fumaric, maleic and itaconic esters, 2-chloroethylvinyl ether, dimethylaminoethyl methacrylate, 2-hydroxyethyl 15 methacrylate, N-vinylsuccinamide, N vinylphthalimide, N-vinylpyrrolidone, butadiene and ethylene. Preferred monomers are acrylates and methacr~lates, with cyclohexyl methacrylate being most preferred.
The proportion in which the above-described high-20 index a~d low-index monomers are mixed varies widely to prov de a polymer having the required index of refraction.
The polymerized low-index monomer preferably comprises from 5 to 100 mole percent Or the :resulting polymerg with the range from 15 to 80 mole percent being most 25 preferred. ~he polymerized high index monomer preferably comprises from 0 to 95 mole percent of the resulting polymer, with the range from 20 to 85 mole percent bein~ most preferred.
In one embodiment, the polymer of the novel ; 30 intensifying screen comprises from 5 to 100 mole percent of recurring units having the formula:
; p~l -(CH2-C)-" C=O
O-R
:-~
~h~rei~:
R- is ~ or alkyl, preferably containing from about 1 to ab3ut 4 carbon atoms, such as methyl, ethyl, propyl, isopropyl, and butyl; and R2 is alkyl, prererably containing from about 1 to about l? carbon atoms, such as methyl, ethyl, propyl and butyl; cycloalkyl~ such as cyclopentyl and cyclohexyl;
aryï prererably containing from about 6 to about 22 carbon a+o."s, such as phenyl3 naphthyl, anthracene, perylene, acena~hthene and rubrene; aralkyl, preferably containing from about 5 to about 20 carbon atoms, such as benzyl, phenylethyl, phenylpropyl, phenylbutyl, tolylbutyl and nh~h~hylme;;nyl; or aryl substituted with alkyl, preferably containing fro~ about 1 to about 20 carbon atoms, such as 3_thyl, ethyl9 isopropyl and hexyl; alkoxy, preferably cor.~aining from about 1 to about 20 carbon atoms, such as methoxy and ethoxy; or heterocyclic, preferably a 5 to 7-membered ring which may be saturated, such as pyrrolidone, morpholine, piperidine, tetrahydrofurane, dioxane and quinaldine, or un~tur~ted, such as pyrrole, ~o~az~le, imidazole, isothiazole 9 furazan and pyrazoline.
A preferred polymer of the novel x-ray inter.sifying screen ~urther comprises from 0 to 95 mole percent of recurring units having the ~ormula:
Rl --(C~12--C)--C=O
Ar-R
wherein:
Ar is arylene, preferably containing from about 6 to about 22 carbon atoms, such as phenylene, naphthalene, anthracene; perylene, acenaphthene and rubrene;
Rl is H or alkyl as described for Rl above;
R3 is H, alkyl, aryl, or aralkyl as described for R above; and ~ -12-R is ~;, alkyl, pre~erably contalning ~rom about 1 to abou~ 23 carbo,. atoms, such as methylg ethyl, isopropyl, and hexyl; alko~y, preferably containing from about 1 to abolt 20 carbo~ atoms, such as methoxy and ethoxy, amino; haloger~ such as chloride and bromide; sul~ide;
sulfoxide~ sulfonate; or heterocyclic, preferably a 5 to 7 membered ring which may be saturatedl such as pyrrolidine~
morpholine, ~iperidine, tetrahydrofurane, dioxane and quinaldine, or unsaturated, ~uch AS pyrrole, isoxazole.
im dazole, isothia7ole, furazan and pyrazoline.
I~is noted that throughout the specification and clai~.s the terms "alkyl", "aryl" and 1'arylene"
incl~de substituved alkyl, aryl and arylene, such as methoxy e'hyl, chlorophenyl and bromonaphthyl.
Exa~les of polymers useful for the novel x-ray intensi~ying screen include:
pGly~l-naph~hyl carbinyl ~ethacrylate-co-S-(l-na~hthyl carbinyl) thioacrylate];
2r poly~l-naphthyl cPrbinyl methacrylate-co-l-bromo-2-naphthylacrylate];
poly[S-(l-naph~hyl carbinyl) thioacrylate-co-benzyl methacrylate~;
poly[S-(2-naphthyl carbinyl) thioacrylate-co-benzyl ~ethacrylate]; and poly[t-butyl methacrylate].
In an especially preferred embodiment, the poly-mer of the novel intensifying screen comprises rro~ 5 to 100 mole percent o~ a polymerlzed co-polymerizable naphthyl carbinyl methacrylate monomer, and fro~. O to 95 mole percent of a polymerized copolymerizable naphthyl car-binyl thioacrylate monomer. In a still further embodiment, the polymer comprises from 5 to lO0 mole percent Or poly-merized l-naphthyl carbinyl methacrylate and from 0 to 95 mole percent of polymerized S-(l-naphthyl carbinyl) thio-acrylate.
The x-ray intensi~ying screen of the in~ention, comprising a substantially isotropic phosphor,which is excited by x-rays and substantially transparent to light emitted by the phosphor, and a polymeric binder carerully seiected so as to ma~ch, within .02, the index of refraction Or the phosphor, is highly transparent. The intensifying screens of the invention generally exhibit a mean free path for li~h' scatter greater than one millimeter~ pre~erably greater than 3 millimeters, for phosphor:binder ratios of 2.5 or larger. This highly transparent screen material allows the use of relatively thick screens wh~ch absorb more of the incident x-ray beam~ and thus results in higher speed. Further, the increased absorption of x-rays decreases quanturi mottle and allows improvement in overall image quality. Further still~ the polymeric binder pro-tects the fragile phosphors from physical damage.
~ he support for the x-ray intensifying screen of the invention includes any material having an index Or relraction equal to or up to 0.05 units higher than the index of refraction of the phosphor of the invention, and ha~r-ng a reflection optical density of at least 1.7 to light emitted by the phosphor. Suitable support materials include polymeric mate,ials such as Lucite~ (poly(methyl methacrylate); Elbite (tourmaline); Formica~ (poly(urea)-for~,aldehyde res n); polyolefins such as polyethylene and polypropylene; pclycarbonates; cellulose acetate; cellulose acetate butyrate; poly(ethylene terephthalate); glass such as Corning Fotoform~ glass having 80 percent of its area covered with holes .015 inch deep and .005 inch in diameter;
and metal such as black anodized aluminum.
The required re~lection optical density o~ 1.7 to light emitted by the phosphor is provided by the use of support materials which are inherently darkly colored, materials which have been dyed or pigmented during manu~;facture to provide a uni~orm dark color throughout, or materials which have undergone a sur~ace treatment such as coating with a dye, pigment or dyed or pigmented material, anodizing in the case of metals, or a combina-tion of the above surface treatments.
The support of the invention also has an indexof refraction equal to or up to 0.05 units higher than the index o~ refraction of the phosphor at its wavelength of maximum emissior.. Ir. one embodiment, a preferred support having botn the required optical densi~y and the required index of refra^tion comprises a conventional support materiai having a thin polymeric layer on the surface on which the fluorescent composition is to be applied. This thin polymeric layer comprises a polymer havlng an index of refraction equal to or up to 0.05 units higher than the index of refraction of` the phosphor at its wavelength of maxi.mum eDission, and a finely divided pigment such as carbon in an a~.ount suffjcient to produce an optical density of 1.7 to light emitted by the phosphor.
The x-ray intensifying screen of the invention compris~ng a highly transparent screen material having high speed and a light-absorbing support having the required reflection optical density, gives high contrast and resolu'ion. The use of a support which has the same or ver~- sligh~ly higher (up to 0.05 higher) index of refraction as that of the phosphor layer decreases the flare of the ima~e and increases contrast.
Tn another em,bodiment of the invention, a particu-larly a~vansagQous f'luorescent composition comprises:
a) from 50 to 90 percent ~y weight of a subs~antially isotropic phosphor which is excited by x-rays and substantially transparent to light emitted by said phosphor; and b) from 10 to 50 percent by weight of a polymer having an index of ref'raction within .02 of the index of refraction Or said phosphor over at least 80 percent of the emission spectrum of said phosphor, said polymer comprising:
i) from 5 to 99 mole percent of recurring units having the formula:
r~l r~
-(CH2-C)-C=02 wherein:
Rl and R2 are as described ~or the polymer of the novel x-ray intensifying screen;
. and ii) from l to 95 mole percent of recurrin~ uniks having the formula:
Rl -(CH2 C)-C=O
Ar-R
wherein:
Ar, Rl, R3 and R are as described for 13 the polymer of the novel x-ray intensirying screen.
Examples of polymers useful in the novel fluores cent composition include:
poly[l-naphvhyl carbinyl methacrylate-co-S-~-naphthyl carbinyl~thioacrylate];
poly[S~ naphthyl carbinyl)thîoacrylate-co-benzyl methacrylate~, and poly~S-(2-naphthylcarbinyl)thioacrylate-co-benzyl methacrylate].
Pre~erred polymers which are useful in the novel fluorescent composition include polymers comprising from 5 to 99 mole percent of a polymerized co-polymerizable naphthyl carbinyl methacrylate monomer, and from l to 95 mole percent of a polymerized copolymerizable naphthyl carbinyl thi0acrylate monomer. ~specially preferred is a polymer comprising from 5 to 99 mole percent Qf recurring units having the ~ormula: CH
-(CH2-C)-C=O
-ÇH2 ~ ; and ~rom 1 to ~5 r..ole percent o~ recurrin~ uni~s having the formul~:
( ~H2 C~ ) C=O
S-ÇH2 The recurring units ~or the polymer and their relative pro~ortions are generally selected to achieve the index ol re~ractior. previously described.
In a further embodiment of the invention, a process for making an intensifying screen comprises the steps o~
a) coa+ing a mixture comprising:
i) from 50 to 90 percent by weignt Or â sub-stantially isotropic phosphor which is excited b~ x-rays and substantially trans-parent to light emitted by said phosphor; and ii) .fror. 10 to 50 percent by wei~ht of at least one copDlymerizable monomer or mixture Or mono~ers, sâid monomer or mixture of monomers, when polymerized~ having an index of refrac-tion within .02 of the index of refraction Or said phosphor over at least 8Q percent of the emission spectrum of said phosphor~
on a support having an index of refraction equal to or up to 0.05 units higher than the index Or refraction of said phosphor and havlng a 2~ reflection optical density of at least 1.7 to light emitted by said phosphor, and b) polymerizing said mixture coâted on said support to produce a polymer comprising recurring units o~ said monomer or monomer mixture~
30 - The mixture comprising the fluorescent compositlon o~ the novel lntensifying screen is preferably prepared by combining a substantially isotropic phosphor in the form Or â free-flowing powder with a polymerizable monomer or mi~;~ure o~ copolymerizable monomers which, when polymerized, exhibit the required index of refraction. The useful phosphGr to monomer ratio varies widely, but prererable ranges are fro~. 50:50 to 90:10 by weight, and more pre-~erably in the range ~ro~, 70:30 to 80:20 by ~eight. ~eneral-ly, the phosphor to monomer ratio is maximized, resulting in a honey~like, viscous mixture, whlch is capable Or being poured. The resulting mixture is optionally de-gassed to remove trapped air bubbles.
- The mixture optionally further comprises from .001 to 1.0 percent by weight~ preferably ~rom 0.1 to 0.5 percent by weight Or a photoinitiator such as 4,4'-bis-chloromethyl benzophenone, benzoin methyl ether, and benzoyl peroxide. It is noted that further additional components are optionally included in the mixtures of the novel process. For exam~le, resins, stabilizers, surface active agen s an~ mold release agents serve to improve ~ilm formation, coating properties, adhesion of the mixture to the support, separability of the mixture from non-support r.aterials, mechanical strength and chemical resistance.
~ he miY.ture of the novel process is coated onto the support to a pre-determined thickness by techniques well-known in the art, such as roll coat~ng, brush coating, solvent coating or x-hopper co~ting. One method of coating the mixture comprises pouring the mixture onto the desired support, covering it with a cover shee~, such as a glass cover sheet~ having appropriate spacers to produce a predetermined coating thickness, and spread~ng the mlxture by applying pressure to the cover sheet to the limit of the spacers.
The optimum coating thickness of the phosphor-monomer mixture depends upon such ~actors as the use to which the coating will be put, the speed desired, the degree o~ image quality deslred, the phosphor selected, the monomer or monomer mixture employed, the phosphor to monomer ratio and the nature o~ other components which may be present in the coating. Useful coating ~:3L7~
th ~X.r.ess^s fcr use in preparing x-ray intenslrying screens ~ - ~ro~J 25 ~G ~5~G microns, with coating thicknesses of from 400 to 120v ~.icrons being preferred. The preferred coa~ing coverage likewise varies widely between about 10 g and about 530 g/ft2, with the range from 50 to 200 G/ft being preferred.
The coating, co~.prising a monomer or mixture Or mono~ers and a phosphor, is preferably polymerized at a temperature of 20-30C by irradiation with a near-ultra-1~ violet la~. Other me~hods of polymerization are similarlyused. Such methods include thermal polymerization, poly-merization by election beam radiation and polymeriz~tion by high energy ga~-.ia irradiation.
After pclymerization, the polymerized mlxture is preferably cooled to room temperature or below, and ar.y cover sheet used to spread the coated mixture and es a~lish coa~ing th.ickness is re~oved. In some cases, release ~s gen~ly initiated, by inserting a blade between the support and the cover sheet to separate the support from the coated polymerized mixture, until Newton's rings are observed a~ the initiation site. The cover sheet is then lifted away, optionally further cooling the cover sheet briefly, for example, with powdered dry ice. Further cooling should be carefully undertaken, however, as over-coolinG the cover sheet is likely to shatter the poly-merized, coated screen mixture.
The resulting polymer has an index of refraction within .02 of the index of refraction of the phosphor over 80 percent of its emission spectrum, thus maintaining a high degree of trar,sparency to the light emitted by the exclted phosphor. The polymer protects the phosphor from mechanical damage, and, if hydrophobic, from damage caused by moisture.
` The process of the invention thus provides a highly transparent ~-ray intensifying screen having satisfactory speed, high contrast and high resolution.
Further the process as described provides a relatively ~7~
inexpensive and straightforward method of manufacturing high speed~ high resolution x-ray intensifying screens without the addition of reflecting pigments.
The following preparations and examples are lncluded for a furth2r understanding of the invention.
Preparation 1 --The phosphor RbI:Tl (.0004) was prepared by add-ing a solution of 0.33 g of thallous acetate ln 500 ml of isopropanol at a rate of 36 ml/min to a vigorously stirred solution of 636 g rubidium iodide in 460 g of water. The temperature of the isopropanol solution was maintained at -29C, and the temperature of the aqueous solution was maintained at about 15C. 200 g of the precipitated rubidium iodide phosphor was collected, carefully remov-ing all of the gupernatan~ lsopropanol water mixture, which was reserved for recovery of unprecipitated rubidium iodide to be used in subsequent preparations. (Any BUp~r-natan~ isopropanol-water mixture remaining with the pre-cipitated phosphor can contaminate the precipitated phosphor with further precipitatlon o~ a phosphor di~fering in composition, and cause unwanted scattering of light in the resulting fluorescent composition.) The precipitated *hallium-activated RbI phosphor, being free Of ~upernatant isopropanol-water mixture 9 was then washed twice with isopropanol in a high speed, ~ood-processing blender, and the precipitate collected on glass filter paper after each washing. The phosphor was vacuum dried and bottled.
The speed of the RbI:Tl (.0004) thus prepared was about equal to that of ~ l, and speeds between 6 and 7 times greater than that o~ DuPont No. 501 commercial CaW04 phosphor were obtained ln the x~ray powder test described in U.S. Patent No. 3,668,142, previously referred to hereln.
Preparatlon 2 --The phosphor KI:Tl (.0003) was prepared by adding a solutlon of 0.4 g thallous acetate ln 1.6 liters of lsopropanol at -29C to a solution of 800 g potassium lodlde in 600 g distllled water at 15C with vigorous stirrlng. The temperature of the ~pernatant solution was ma nta~ned av about 14~C. The rate o~ addition was 35 ml/min. The crystals of the precipitated phosphor were free from defects and had cubic morphology with crystal sizes in the range from about 10-20 microns. The speed of the phosphor, measured after precipitation, washing, and drying, by the method used in U.S. 3,66~9142 was about seven times that of commercial calclum tungstate.
Preparation 3 A mixture of 66 g of cyclopentadiene and 500 ml 13 o, methylene chloride was stirred with 90 g of acryloyl chloride at dry ice temperature (-78.5DC) and allowed to warm slowly to room temperature over 24 hours. The reaction product was then distilled. The resulting bicycloheptane carbonyl chloride thus obtained was allowed to react with l-(naphthylcarbinyl)rnercaptan and rerluxed in methylene chloride (b.p. 40-41C) while one equivalent of d isocro~ylethylamine was slowly added to the mixture.
The product was vacuum distilled, using a 250C oil bath, un~er which conditions the cyclopentad~ene split o~, giving S~ naphthylcarblnyl)thioacrylate in good yield.
thin-layer chromatograph (50:50 hexane/e'her, silica gel) of the resulting product indicated an ~f value of 0.59 to 0.72.
Preparation 4 l-naphthyl carbinyl methacr~late was prepared by catalytic transesterification of an excess quantity of methyl methacrylate with the alcohol l-naphthyl carbinol.
The by-product, methanol, was conkinuously removed by azeotropic dist~llation and/or use o~ molecular sleves~
thus pulling the reversible reaction towards completion.
When the reaction was essentially complete, the excess methyl methacrylate was removed by distillation at atmospheric pressure. A small amount (~rom 5 to 25%) of the unreacted higher alcohol l--naphthyl carbinol remained in the resultlng l-naphthyl carbinyl methacrylate.
~ ,~ ~oe Preparation~
In an alternative synthesis o~ l~naphthyl carbinyl methacrylate, l-~chloromethyl)naphthalene is treated with one equivalent o~ potassium methacrylate ~n dimethyl sulfoxide. m e pota~sium methacrylate employed is either previously isolated or formed in situ from potassium hydroxide and methacrylic acid.
The reaction is continued at 70~C for 30 minutes. The resulting l-naphthylcarbinyl methacrylate is isolated in 93-98% yield, virtually ~ree from c~ntaminants.
Preparation 6 Aluminum plates were anodized in 12-15 percent H2S04 at 70~ and 12-14 amperes/ft2. The porous deposit was treated with aluminum Black B ~ dye (a registered trademark of Sandoz Colors and Chemicals) and then sealed with hot water or nickel acetate solution. The resulting support exhibited a~ optical density of 2.34 when over-coated with a mLxture of rubidium iodide and polymer havin~ matched indexes of refraction. Al~hough the index of re~raction o~ anodized aluminum is not pre-cisely know." it is thought to be about 1.76, which is less than 0.05 un~ts higher than that of rubidium iodide at 425 nm, the region of maximu~. emission.
Example 1 A mixture of 100 g of thallium-activated potassium iod de phosphor (.0003), as prepared in Preparation 2, and 40 g Gf a 4:1 mixture of S~ naphthyl carbinyl) thio-acrylate, as prepared in Preparation 3, and l-naphthyl carbinyl methacrylate, as prepared in Preparation 4, con-
Any substantially isotropic phosphor which is excited by x~-rays and substantially transparent to the light emitted by the excited phosphor is usefuI in preparing the fluorescent composition. The term substantially iso-tropic phosphor is 30 used herein to mean a crystalline phosphor having substantially the same optical properties in all ddrections of the crystal~
and that the crystalline phosphor is substantially free from defects! such as cracks and inclusion,s, which cause scattering of light. Useful phosphors include activated alkali metal halides, such as KCl:Sb, CsBr:Tl, KI:Tl, KBr:Tlt KCl:Tl, RbCl:Tl, RbBr:Tl and RbI:Tl; alkaline earth halides such as BaF2 and Ba~Cl; activated alkaline earth halides such as Ca~2:Eu, SrC12:Sm, SrF2:Eu, BaFCl:Sr, Eu, BaFCl:Eu and SrF2:Sm; activated metal silicates such as BaSiO3:Eu, CaSiO3:Mn and Zn2SiO~:Mn; mixed metal fluorides such as KCdF3:Mn and CsCdF3:Mn; metal sulfates such as lanthanide-activated metal sulfates such as BaSO4:Sr, Eu, SrSO4:Eu, BaSO4:Eu, ZnSO4:Mn and Cs3SO~:Ce; metal gallates such as ZnGa2O4:Mn; and phosphates such as lanthanide-activated phosphates such as Ba2P4O7:Eu and Ca3(PO4)2:Ce examples of phosphors are described in U.S. Patent Nos.
4,100,101, 2,303,g63, 3,163,610, 3~163,603 and 3,506,584 and in R.C. Pastor et al, Mat. Res. Bull., 15 469-475 (1980). Typical transparent phosphors include RbI:Tl;
KI:Tl; BaFCl:Sr, Eu; BaSO4:Sr, Eu; CsCdF3Mn; BaF2;
KCdF3:Mn; and SrF2. Preferred phosphors are RbI:Tl;
KI:Tl~; BaFCl:Sr, Eu; CsCdF3:Mn; BaSO4:Sr, Eu; and BaSO4:Pb.
The above-described phosphors are prepared by any conventional method for preparing isotropic phos-phors, such as by introducing the anions and cations which form the phosphor into a reaction solution,main-taining an excess of up to 1 molar of an anion or cation throughout the reaction mixture, preventing local excesses of cations or anions, and thus slowly growing crystals of the phosphor to at least 0.5 micron, as described in U.S. Patent No. 3,668,1l~2 issued June 6, 1972 to Luckey.
Other methods for preparing isotropic phosphors which are excited by x-rays and substantially transparent to the emitted light, include precipitation at elevated temperatures and super-atmospheric pressures described in ~uthruff, U.S. Patent No. 2,285,464; precipitation followed by firing, fusion, and grinding to the desired particle size; and ignition in the presence of a flux~
The method of U.S. Patent No. 3,668,142 is the preferred method for preparing the isotropic phosphors.
-7a-These screens can be modlfied so that they are useful in the apparatus and methods for producing images that are described in U.S.3,8599527~ U.S~
4,346,295 and U.S. 4,236,078. In this modification an essentially isotropic storage phosphor is eoated in a binder on a support that has the characteristics described below. The phosphor is excited by a pat-tern of radiation of a first wavelength. The phos-phor is then exposed to radia~ion of a second wave length which causes the said storage medium to emit a ~hird wavelength of radiation having an intensity pattern representative of ~he stored image. The binder used in making this screen matches the index of refraction of the phosphor at th~ second wave-length and the support for the screen is selected sothat it does not reflect the radiation at the second wavelength. The index of refraction of ~he binder at the third wavelength is preferably selected so that i~ does not match that of the phosphor and the sup-port of the screen may reflect the radiation at thethird wavelength. Thus, the radiation at the third wavelength, which is emitted when the phosphor is irradiated at the second wavelength, is not trapped by total internal reflection or by the support, but escapes from the screen and is efficiently collected by a photomultiplier tube with appropriate optics or by other photosensors which respond efficien~ly to the radiation at the third wavelength. Screens of this type are particularly useful for radiography and other applications in which a pattern of hi8h energy radiation is absorbed by the phosphor 9 then released by scanning the screen wlth a laser beam that has a wavelength equal to that where the index of refrac tion of the phosphor and binder are matched and where . ~
~7~
-7b-the support of the screen has minimum reflectance.
Ideally, the beam from the laser follows the path of the high energy radiation 60 that the resolution of the image from the screen i6 determined by ~he dimen-sions of the laser beam. The light released from thephosphor by the laser is collected by an appropriate photosensor, amplified, and the signal displayed on a cathode ray ~ube or recorded on an image recording medium to form the imageO Appropriate phosphors com-prise the barium alkaline earth metal fluorohalidesof U.S. 4,261,854 and U.S. 4,239,968, and other storage phosphors which have indices of refracti.on less than about 1.75 in the visible region of the spectrum.
, ~i ~ ne phosphor crystals are optionally activated to obta n the desired speed by any conventlonal method of activation. One method is the addition o~ a solution o~ a small amount (about .05 percent by weight) o~ the activating ion in a solvent, such as isopropanol 9 to a vigorously stirred solution of the lsotropic host in a solvent, such as water, at very low temperatures (-30 to ~20C), followed by collection of the precipitated activated phosphor.
The substantially isotropic phosphors Or the invention generally have crystalline morphologies which are cubic or substantially cubic. The substantially isotropic phosphors of the invention generally have crystal sizes in the range rrom about 1 to about 50 microns, with the size range from about 10 to about 20 micro~s bein~ preferred.
~ ne novel x-ray ~ntensifying screen includes an~ polymer having an index of refraction within .02 of the index of refraction of the phosphor over at least Bo percent of the emission spectrum.
The selection of the polymer for the novel x-ray intensifying screen is depenclent on the index of refract~on of the selected substantially isotropic phosphor at its emission wavelength. The index of 25 refraction of the phosphor is determined by measuring the transmission spectra of the phosphor mixed with a series of Cargille liquids~ as described in "~he Particle Atlas", McCrone, Dra~tz and Delly, Ann Arbor Science Publishers, Inc., 1967, and determining the 30 wavelength at ~nich the index of refraction of th~ phosphor and the liquid match. A phosphor dispersion curve is obtained by plotting the wavelengths o~ maximum transmission ror the series on the ~amily o~ Cargille dispersion curves publlshed in "The Particle Atlas" referred to above. The phosphor dispersion curve thus obtained is used directly to find the lndex of rerraction required for the polymer of the novel transparent x-ray intensi~ying screen.
l7~
~ he polymer havin~ the required index of rerrac-tion, i.e., an index of refraction within .02 of the refraction of the phosphor over at least 80 percent Or its emission spectrur,, comprises a single polymerized monomer, or the polymer comprises a mixture of two or more poly-merized copolymerizable monomers. Generally, the polymer comprises two copolymerizable polymerized monomers, one of which, when polymerized, provides a polymer o~ higher index of refraction than required, and one which~ when polymerized, provides a lower index of rerraction than required. The relative proportions of the two monomers are advusted to provide the required rerraction index.
Calculated formulations are verified by measuring the transmission curve ol a sample coating o~ the fluorescent composition of the novel intensifying screen on a spectro~
photometer. h wavelength of maximum transmission which is less ~han tha~ of the phosphor er.ission wavelen~th indicates that the refractive index of the polymeric b~nder is too low. A wavelength Or maximum transmission 2~ which is greater than that of the phosphor emission wave-leng~h indicates that the refractive index of the polymer is too high.
Morlomers which, when polymerized, provide an index of refraction higher than that o~ the phosphor selected generally ~rovide an index of refraction above 1.4 3 preferably in the range from 1.40 to 1.75. Examples of monomers which, when polymerized, provide an index of refraction higher than that of the pho~phor selected, and thus can be mixed with monomers having a lower index of refractlon to become useful herein, include S~
naphthyl carbinyl) thioacrylate, naphthyl acrylate, 1-bromo-2-nap~hylacrylate and naphthylmethacrylate. The pre~erred monomer is S-(l-naphthyl carbinyl)thioacrylate.
Monomers which, when polymerized, provide an index of re~raction lower than that of the pho~phor generally provide an index of refraction ranging from about 1.40 to about 1.75, preferably in the range from --10~
1.40 to 1.60. Examples of monomers which, when poly-merized, provide ~n index of refrackion lower than that Or the phosphor selected and thus are useful when mlxed with monomers having a higher index Or refraction~
include copolymerizable ethylenically unsaturated mono-mers such as acrylates and methacrylates such as methyl acrylate~ ethyl acrylate, propyl acrylate, bu~yl acrylate, butyl methacrylate and cyc]ohexyl methacrylate; vinyl ester~, amides, nitriles, ketones, halides, ethers, 13 olefins, and diolefins as exemplified by acrylonitrile, methacrylonitrile, styrene, ~-methyl ~tyrene, acrylamide~
methacrylamide, vinyl chloride, methyl vinyl ketone, fumaric, maleic and itaconic esters, 2-chloroethylvinyl ether, dimethylaminoethyl methacrylate, 2-hydroxyethyl 15 methacrylate, N-vinylsuccinamide, N vinylphthalimide, N-vinylpyrrolidone, butadiene and ethylene. Preferred monomers are acrylates and methacr~lates, with cyclohexyl methacrylate being most preferred.
The proportion in which the above-described high-20 index a~d low-index monomers are mixed varies widely to prov de a polymer having the required index of refraction.
The polymerized low-index monomer preferably comprises from 5 to 100 mole percent Or the :resulting polymerg with the range from 15 to 80 mole percent being most 25 preferred. ~he polymerized high index monomer preferably comprises from 0 to 95 mole percent of the resulting polymer, with the range from 20 to 85 mole percent bein~ most preferred.
In one embodiment, the polymer of the novel ; 30 intensifying screen comprises from 5 to 100 mole percent of recurring units having the formula:
; p~l -(CH2-C)-" C=O
O-R
:-~
~h~rei~:
R- is ~ or alkyl, preferably containing from about 1 to ab3ut 4 carbon atoms, such as methyl, ethyl, propyl, isopropyl, and butyl; and R2 is alkyl, prererably containing from about 1 to about l? carbon atoms, such as methyl, ethyl, propyl and butyl; cycloalkyl~ such as cyclopentyl and cyclohexyl;
aryï prererably containing from about 6 to about 22 carbon a+o."s, such as phenyl3 naphthyl, anthracene, perylene, acena~hthene and rubrene; aralkyl, preferably containing from about 5 to about 20 carbon atoms, such as benzyl, phenylethyl, phenylpropyl, phenylbutyl, tolylbutyl and nh~h~hylme;;nyl; or aryl substituted with alkyl, preferably containing fro~ about 1 to about 20 carbon atoms, such as 3_thyl, ethyl9 isopropyl and hexyl; alkoxy, preferably cor.~aining from about 1 to about 20 carbon atoms, such as methoxy and ethoxy; or heterocyclic, preferably a 5 to 7-membered ring which may be saturated, such as pyrrolidone, morpholine, piperidine, tetrahydrofurane, dioxane and quinaldine, or un~tur~ted, such as pyrrole, ~o~az~le, imidazole, isothiazole 9 furazan and pyrazoline.
A preferred polymer of the novel x-ray inter.sifying screen ~urther comprises from 0 to 95 mole percent of recurring units having the ~ormula:
Rl --(C~12--C)--C=O
Ar-R
wherein:
Ar is arylene, preferably containing from about 6 to about 22 carbon atoms, such as phenylene, naphthalene, anthracene; perylene, acenaphthene and rubrene;
Rl is H or alkyl as described for Rl above;
R3 is H, alkyl, aryl, or aralkyl as described for R above; and ~ -12-R is ~;, alkyl, pre~erably contalning ~rom about 1 to abou~ 23 carbo,. atoms, such as methylg ethyl, isopropyl, and hexyl; alko~y, preferably containing from about 1 to abolt 20 carbo~ atoms, such as methoxy and ethoxy, amino; haloger~ such as chloride and bromide; sul~ide;
sulfoxide~ sulfonate; or heterocyclic, preferably a 5 to 7 membered ring which may be saturatedl such as pyrrolidine~
morpholine, ~iperidine, tetrahydrofurane, dioxane and quinaldine, or unsaturated, ~uch AS pyrrole, isoxazole.
im dazole, isothia7ole, furazan and pyrazoline.
I~is noted that throughout the specification and clai~.s the terms "alkyl", "aryl" and 1'arylene"
incl~de substituved alkyl, aryl and arylene, such as methoxy e'hyl, chlorophenyl and bromonaphthyl.
Exa~les of polymers useful for the novel x-ray intensi~ying screen include:
pGly~l-naph~hyl carbinyl ~ethacrylate-co-S-(l-na~hthyl carbinyl) thioacrylate];
2r poly~l-naphthyl cPrbinyl methacrylate-co-l-bromo-2-naphthylacrylate];
poly[S-(l-naph~hyl carbinyl) thioacrylate-co-benzyl methacrylate~;
poly[S-(2-naphthyl carbinyl) thioacrylate-co-benzyl ~ethacrylate]; and poly[t-butyl methacrylate].
In an especially preferred embodiment, the poly-mer of the novel intensifying screen comprises rro~ 5 to 100 mole percent o~ a polymerlzed co-polymerizable naphthyl carbinyl methacrylate monomer, and fro~. O to 95 mole percent of a polymerized copolymerizable naphthyl car-binyl thioacrylate monomer. In a still further embodiment, the polymer comprises from 5 to lO0 mole percent Or poly-merized l-naphthyl carbinyl methacrylate and from 0 to 95 mole percent of polymerized S-(l-naphthyl carbinyl) thio-acrylate.
The x-ray intensi~ying screen of the in~ention, comprising a substantially isotropic phosphor,which is excited by x-rays and substantially transparent to light emitted by the phosphor, and a polymeric binder carerully seiected so as to ma~ch, within .02, the index of refraction Or the phosphor, is highly transparent. The intensifying screens of the invention generally exhibit a mean free path for li~h' scatter greater than one millimeter~ pre~erably greater than 3 millimeters, for phosphor:binder ratios of 2.5 or larger. This highly transparent screen material allows the use of relatively thick screens wh~ch absorb more of the incident x-ray beam~ and thus results in higher speed. Further, the increased absorption of x-rays decreases quanturi mottle and allows improvement in overall image quality. Further still~ the polymeric binder pro-tects the fragile phosphors from physical damage.
~ he support for the x-ray intensifying screen of the invention includes any material having an index Or relraction equal to or up to 0.05 units higher than the index of refraction of the phosphor of the invention, and ha~r-ng a reflection optical density of at least 1.7 to light emitted by the phosphor. Suitable support materials include polymeric mate,ials such as Lucite~ (poly(methyl methacrylate); Elbite (tourmaline); Formica~ (poly(urea)-for~,aldehyde res n); polyolefins such as polyethylene and polypropylene; pclycarbonates; cellulose acetate; cellulose acetate butyrate; poly(ethylene terephthalate); glass such as Corning Fotoform~ glass having 80 percent of its area covered with holes .015 inch deep and .005 inch in diameter;
and metal such as black anodized aluminum.
The required re~lection optical density o~ 1.7 to light emitted by the phosphor is provided by the use of support materials which are inherently darkly colored, materials which have been dyed or pigmented during manu~;facture to provide a uni~orm dark color throughout, or materials which have undergone a sur~ace treatment such as coating with a dye, pigment or dyed or pigmented material, anodizing in the case of metals, or a combina-tion of the above surface treatments.
The support of the invention also has an indexof refraction equal to or up to 0.05 units higher than the index o~ refraction of the phosphor at its wavelength of maximum emissior.. Ir. one embodiment, a preferred support having botn the required optical densi~y and the required index of refra^tion comprises a conventional support materiai having a thin polymeric layer on the surface on which the fluorescent composition is to be applied. This thin polymeric layer comprises a polymer havlng an index of refraction equal to or up to 0.05 units higher than the index of refraction of` the phosphor at its wavelength of maxi.mum eDission, and a finely divided pigment such as carbon in an a~.ount suffjcient to produce an optical density of 1.7 to light emitted by the phosphor.
The x-ray intensifying screen of the invention compris~ng a highly transparent screen material having high speed and a light-absorbing support having the required reflection optical density, gives high contrast and resolu'ion. The use of a support which has the same or ver~- sligh~ly higher (up to 0.05 higher) index of refraction as that of the phosphor layer decreases the flare of the ima~e and increases contrast.
Tn another em,bodiment of the invention, a particu-larly a~vansagQous f'luorescent composition comprises:
a) from 50 to 90 percent ~y weight of a subs~antially isotropic phosphor which is excited by x-rays and substantially transparent to light emitted by said phosphor; and b) from 10 to 50 percent by weight of a polymer having an index of ref'raction within .02 of the index of refraction Or said phosphor over at least 80 percent of the emission spectrum of said phosphor, said polymer comprising:
i) from 5 to 99 mole percent of recurring units having the formula:
r~l r~
-(CH2-C)-C=02 wherein:
Rl and R2 are as described ~or the polymer of the novel x-ray intensifying screen;
. and ii) from l to 95 mole percent of recurrin~ uniks having the formula:
Rl -(CH2 C)-C=O
Ar-R
wherein:
Ar, Rl, R3 and R are as described for 13 the polymer of the novel x-ray intensirying screen.
Examples of polymers useful in the novel fluores cent composition include:
poly[l-naphvhyl carbinyl methacrylate-co-S-~-naphthyl carbinyl~thioacrylate];
poly[S~ naphthyl carbinyl)thîoacrylate-co-benzyl methacrylate~, and poly~S-(2-naphthylcarbinyl)thioacrylate-co-benzyl methacrylate].
Pre~erred polymers which are useful in the novel fluorescent composition include polymers comprising from 5 to 99 mole percent of a polymerized co-polymerizable naphthyl carbinyl methacrylate monomer, and from l to 95 mole percent of a polymerized copolymerizable naphthyl carbinyl thi0acrylate monomer. ~specially preferred is a polymer comprising from 5 to 99 mole percent Qf recurring units having the ~ormula: CH
-(CH2-C)-C=O
-ÇH2 ~ ; and ~rom 1 to ~5 r..ole percent o~ recurrin~ uni~s having the formul~:
( ~H2 C~ ) C=O
S-ÇH2 The recurring units ~or the polymer and their relative pro~ortions are generally selected to achieve the index ol re~ractior. previously described.
In a further embodiment of the invention, a process for making an intensifying screen comprises the steps o~
a) coa+ing a mixture comprising:
i) from 50 to 90 percent by weignt Or â sub-stantially isotropic phosphor which is excited b~ x-rays and substantially trans-parent to light emitted by said phosphor; and ii) .fror. 10 to 50 percent by wei~ht of at least one copDlymerizable monomer or mixture Or mono~ers, sâid monomer or mixture of monomers, when polymerized~ having an index of refrac-tion within .02 of the index of refraction Or said phosphor over at least 8Q percent of the emission spectrum of said phosphor~
on a support having an index of refraction equal to or up to 0.05 units higher than the index Or refraction of said phosphor and havlng a 2~ reflection optical density of at least 1.7 to light emitted by said phosphor, and b) polymerizing said mixture coâted on said support to produce a polymer comprising recurring units o~ said monomer or monomer mixture~
30 - The mixture comprising the fluorescent compositlon o~ the novel lntensifying screen is preferably prepared by combining a substantially isotropic phosphor in the form Or â free-flowing powder with a polymerizable monomer or mi~;~ure o~ copolymerizable monomers which, when polymerized, exhibit the required index of refraction. The useful phosphGr to monomer ratio varies widely, but prererable ranges are fro~. 50:50 to 90:10 by weight, and more pre-~erably in the range ~ro~, 70:30 to 80:20 by ~eight. ~eneral-ly, the phosphor to monomer ratio is maximized, resulting in a honey~like, viscous mixture, whlch is capable Or being poured. The resulting mixture is optionally de-gassed to remove trapped air bubbles.
- The mixture optionally further comprises from .001 to 1.0 percent by weight~ preferably ~rom 0.1 to 0.5 percent by weight Or a photoinitiator such as 4,4'-bis-chloromethyl benzophenone, benzoin methyl ether, and benzoyl peroxide. It is noted that further additional components are optionally included in the mixtures of the novel process. For exam~le, resins, stabilizers, surface active agen s an~ mold release agents serve to improve ~ilm formation, coating properties, adhesion of the mixture to the support, separability of the mixture from non-support r.aterials, mechanical strength and chemical resistance.
~ he miY.ture of the novel process is coated onto the support to a pre-determined thickness by techniques well-known in the art, such as roll coat~ng, brush coating, solvent coating or x-hopper co~ting. One method of coating the mixture comprises pouring the mixture onto the desired support, covering it with a cover shee~, such as a glass cover sheet~ having appropriate spacers to produce a predetermined coating thickness, and spread~ng the mlxture by applying pressure to the cover sheet to the limit of the spacers.
The optimum coating thickness of the phosphor-monomer mixture depends upon such ~actors as the use to which the coating will be put, the speed desired, the degree o~ image quality deslred, the phosphor selected, the monomer or monomer mixture employed, the phosphor to monomer ratio and the nature o~ other components which may be present in the coating. Useful coating ~:3L7~
th ~X.r.ess^s fcr use in preparing x-ray intenslrying screens ~ - ~ro~J 25 ~G ~5~G microns, with coating thicknesses of from 400 to 120v ~.icrons being preferred. The preferred coa~ing coverage likewise varies widely between about 10 g and about 530 g/ft2, with the range from 50 to 200 G/ft being preferred.
The coating, co~.prising a monomer or mixture Or mono~ers and a phosphor, is preferably polymerized at a temperature of 20-30C by irradiation with a near-ultra-1~ violet la~. Other me~hods of polymerization are similarlyused. Such methods include thermal polymerization, poly-merization by election beam radiation and polymeriz~tion by high energy ga~-.ia irradiation.
After pclymerization, the polymerized mlxture is preferably cooled to room temperature or below, and ar.y cover sheet used to spread the coated mixture and es a~lish coa~ing th.ickness is re~oved. In some cases, release ~s gen~ly initiated, by inserting a blade between the support and the cover sheet to separate the support from the coated polymerized mixture, until Newton's rings are observed a~ the initiation site. The cover sheet is then lifted away, optionally further cooling the cover sheet briefly, for example, with powdered dry ice. Further cooling should be carefully undertaken, however, as over-coolinG the cover sheet is likely to shatter the poly-merized, coated screen mixture.
The resulting polymer has an index of refraction within .02 of the index of refraction of the phosphor over 80 percent of its emission spectrum, thus maintaining a high degree of trar,sparency to the light emitted by the exclted phosphor. The polymer protects the phosphor from mechanical damage, and, if hydrophobic, from damage caused by moisture.
` The process of the invention thus provides a highly transparent ~-ray intensifying screen having satisfactory speed, high contrast and high resolution.
Further the process as described provides a relatively ~7~
inexpensive and straightforward method of manufacturing high speed~ high resolution x-ray intensifying screens without the addition of reflecting pigments.
The following preparations and examples are lncluded for a furth2r understanding of the invention.
Preparation 1 --The phosphor RbI:Tl (.0004) was prepared by add-ing a solution of 0.33 g of thallous acetate ln 500 ml of isopropanol at a rate of 36 ml/min to a vigorously stirred solution of 636 g rubidium iodide in 460 g of water. The temperature of the isopropanol solution was maintained at -29C, and the temperature of the aqueous solution was maintained at about 15C. 200 g of the precipitated rubidium iodide phosphor was collected, carefully remov-ing all of the gupernatan~ lsopropanol water mixture, which was reserved for recovery of unprecipitated rubidium iodide to be used in subsequent preparations. (Any BUp~r-natan~ isopropanol-water mixture remaining with the pre-cipitated phosphor can contaminate the precipitated phosphor with further precipitatlon o~ a phosphor di~fering in composition, and cause unwanted scattering of light in the resulting fluorescent composition.) The precipitated *hallium-activated RbI phosphor, being free Of ~upernatant isopropanol-water mixture 9 was then washed twice with isopropanol in a high speed, ~ood-processing blender, and the precipitate collected on glass filter paper after each washing. The phosphor was vacuum dried and bottled.
The speed of the RbI:Tl (.0004) thus prepared was about equal to that of ~ l, and speeds between 6 and 7 times greater than that o~ DuPont No. 501 commercial CaW04 phosphor were obtained ln the x~ray powder test described in U.S. Patent No. 3,668,142, previously referred to hereln.
Preparatlon 2 --The phosphor KI:Tl (.0003) was prepared by adding a solutlon of 0.4 g thallous acetate ln 1.6 liters of lsopropanol at -29C to a solution of 800 g potassium lodlde in 600 g distllled water at 15C with vigorous stirrlng. The temperature of the ~pernatant solution was ma nta~ned av about 14~C. The rate o~ addition was 35 ml/min. The crystals of the precipitated phosphor were free from defects and had cubic morphology with crystal sizes in the range from about 10-20 microns. The speed of the phosphor, measured after precipitation, washing, and drying, by the method used in U.S. 3,66~9142 was about seven times that of commercial calclum tungstate.
Preparation 3 A mixture of 66 g of cyclopentadiene and 500 ml 13 o, methylene chloride was stirred with 90 g of acryloyl chloride at dry ice temperature (-78.5DC) and allowed to warm slowly to room temperature over 24 hours. The reaction product was then distilled. The resulting bicycloheptane carbonyl chloride thus obtained was allowed to react with l-(naphthylcarbinyl)rnercaptan and rerluxed in methylene chloride (b.p. 40-41C) while one equivalent of d isocro~ylethylamine was slowly added to the mixture.
The product was vacuum distilled, using a 250C oil bath, un~er which conditions the cyclopentad~ene split o~, giving S~ naphthylcarblnyl)thioacrylate in good yield.
thin-layer chromatograph (50:50 hexane/e'her, silica gel) of the resulting product indicated an ~f value of 0.59 to 0.72.
Preparation 4 l-naphthyl carbinyl methacr~late was prepared by catalytic transesterification of an excess quantity of methyl methacrylate with the alcohol l-naphthyl carbinol.
The by-product, methanol, was conkinuously removed by azeotropic dist~llation and/or use o~ molecular sleves~
thus pulling the reversible reaction towards completion.
When the reaction was essentially complete, the excess methyl methacrylate was removed by distillation at atmospheric pressure. A small amount (~rom 5 to 25%) of the unreacted higher alcohol l--naphthyl carbinol remained in the resultlng l-naphthyl carbinyl methacrylate.
~ ,~ ~oe Preparation~
In an alternative synthesis o~ l~naphthyl carbinyl methacrylate, l-~chloromethyl)naphthalene is treated with one equivalent o~ potassium methacrylate ~n dimethyl sulfoxide. m e pota~sium methacrylate employed is either previously isolated or formed in situ from potassium hydroxide and methacrylic acid.
The reaction is continued at 70~C for 30 minutes. The resulting l-naphthylcarbinyl methacrylate is isolated in 93-98% yield, virtually ~ree from c~ntaminants.
Preparation 6 Aluminum plates were anodized in 12-15 percent H2S04 at 70~ and 12-14 amperes/ft2. The porous deposit was treated with aluminum Black B ~ dye (a registered trademark of Sandoz Colors and Chemicals) and then sealed with hot water or nickel acetate solution. The resulting support exhibited a~ optical density of 2.34 when over-coated with a mLxture of rubidium iodide and polymer havin~ matched indexes of refraction. Al~hough the index of re~raction o~ anodized aluminum is not pre-cisely know." it is thought to be about 1.76, which is less than 0.05 un~ts higher than that of rubidium iodide at 425 nm, the region of maximu~. emission.
Example 1 A mixture of 100 g of thallium-activated potassium iod de phosphor (.0003), as prepared in Preparation 2, and 40 g Gf a 4:1 mixture of S~ naphthyl carbinyl) thio-acrylate, as prepared in Preparation 3, and l-naphthyl carbinyl methacrylate, as prepared in Preparation 4, con-
3~ taining 0.3 percent by weight of 4,4'-bis-chloromethyl benzoquinone was degassed under vacuum. A por~ion of the mixture was photopolymerized between two glass sheets to ~orm an unsupported screen, and released. The unsupported sçreen was placed ln a Cary ~ 17 spectrophotometer and its optical density was measured using an unsupported screen containlng only photopolymerized polymer (lacking the phosphor) as a reference. The optical density of the -22~ 7 unsupported screen was used to calculate the mean ~ree ~ath of light through the screen. The mean free path was calculated to be at least 2.3 mm.
Another portion of the mixture was coated at di~erent thicknesses on a black anodized aluminum support as prepared in Preparation ~ and photopolymerized under glass cover shee's. Radiographs were made by exposing Lo-Dose~ film in contact with these experimental supported screens as back screens wlth 70 kVp x-rays. A control radiograph was ~ade by likewise exposing Lo-Dose~ film in contac-~ with a DuPont~ Par Speed Inténsifying screen in order to obtain the relative speeds of the experimental screens. The di~ference in speed was calculated through the known density vs. lo~ exposure curve ~or Lo~Dose~
film ~rom the densities which resulted on the exposed and developed rilms. The following results were obtained.
Screen ~^Xness Screer C~verage Relative Speed 10 micron lead (mi ron~? (g/~t ) PAR = 100* bar test o~ect Resolution 20 405 61 17~ 3.15 lp/m.r, 7~0 113 26~ 2.24-2.5 1115 15Q 325 2.0 *~ont~ ~r $~ee~ Intens~yi~ Screen Example 2 . . .
A mixture of 35.5 g o~ the thallium-activated rubidium iodide phosphor (.0004) as prepared in Prepara-tion 1 and 10 g o~ a 60:40 mixture of l-naphthyl carbinyl methacrylate and l-bromo-2-naphthylacrylate containing 0.3 percent 4,4'-bis-chloromethyl benzophenone was spread on a black anodized aluminum support and covered with a glass sheet while being photopolymerized. When polymeri-zation was complete, the glass sheet was released. The resulting transparent screen was 500 microns thick and had a coverage o~ 89 g of phosphor per square foot.
Radiographs made with this screen as a back screen with Lo-Dos Film at 70 kVp gave a relatlve radiographic speed tcalculated as in Example 1) of 255 compared to 285 ror a DuPont Hi-Plus~ Screen with Lo-Dose~ Film. When a bone and bead test object was employed in -the same comparison, better image quality was obtained with the transparent screen.
_ample 3 A mixture of 250 g of the thallium-activated rubidium iodide and 65 g of a 3:1 mixture of l-naphthyl carbinyl methacrylate and S-(l-naphthyl carbinyl) thioacr~la-te which also contained 0.3 percent by weight of 4,4'-bis-chloromethyl benzophenone was degassed under vacuum and then coated three ways: (1) on black anodized aluminum support, (2) on reflective aluminum support on an optically flat surface, and (3) on no support (self-supporting film). All three coatings were of equal thickness and were photopolymerized. Radiographs were made with these three screens, along with the DuPont Hi-Plus~
screen, using Lo~Dose~ Film, 70 k~p x-rays and a 20 ,u lead bar test object. The resolution of the radiographs was as follows:
Hi-Plus~ Screen 4.0 lp/mm Black Aluminum Support 4.0 lp/mm Reflective Aluminum Support 1.8 lp/mm Unsupported 1.8 lp/mm The resolution of the screen having a black support showed a dramatic increase both over the resolution of the screen having a reflective support and over that of the unsupported screen.
Example 4 A mixture of 136.8 g of thallium-activated rubidium iodide (.0004), 40.0 g of a 3:1 mixture of l-naphthyl carbinyl methacrylate containing up to 25 percent l-naphthyl carbinol and S~ naphthyl carbinyl) thioacrylate, and 0.3 percent by weight o~ 4,4'-bis-chloromethyl benzophenone was degassed under vacuum. The mixture was then coated on a support consisting of inlaid strips of black polished Formica~, black anodized aluminuzn, black Corning FotoEor glass having 80 percent of its area covered with holes, .005 inch in diameter and .015 inch deep, and dark blue ~.~'7~6~
-2~
tourmaline in a matrix of black Lucite~ plastic. The mixture was spread evenly across the support so thai the different types of support were coated with an equal thickness of the mi~ture. A glass cover sheet was placed on the mixture, and the mixture was photopolymerized. The cover sheet was removed, and the reflection optical densities of the dif~erent areas were measured. A 70 kVp radiograph of a 10 micron lead bar resolution test ob~ect was made using the screen as a back screen with DuPont Lo-Dos ~ film. The radiograph made using this transparent screen was compared with a control radiograph made with Lo-Dose~ film and using an opaque Hi-Plu ~ screen.
Radiographic speed was determined as in Example 1. The results obtained were as follows:
Refrac-tive Reflection Radiographic Resolution i5 Support Index nd_ optical Density Speed (lp/mn) Lucite~ 1.49 2.25 315 2.5-2.8 Fotofor ~
Glass - 1.87 250 3.15 tourmaline 1.64 2.57 250 3.15 20 Formica~ 1.65 2.17 245 3.15-3.55 Black anodized Aluminum 1.76 2.34 245 3.55 Hi-Plus~ Screen Control (opaque) - - 285 3.55 The results indicated that the optimum combination of speed and resolution were obtained when the fluoxescent composition mixture was coated on a black anodized aluminum surface for the particular transparent phosphor-polymer combination selected. Further, the results showed that the transparent screen having a black anodized aluminum support exhibited resolution equal to and radiographic speed nearly equal to the conYentional opaque control screen; however, the trans-parent screen of the invention displayed less quantum mottle than the conventional opaque screen.
Example 5 A mixture of 180 g of finely powdered Ba Sr 06FCl:Eu (.006) phosphor and 51 g of a blend of benzyl methacrylate and l~naphthylcarbinyl methacrylate ~approximately 50:50 by weight) was degassed under vacuum and spread on a black anodized aluminum support.
A glass cover sheet was placed on top of the layer and the mixture was polymerized by irradiation with an ultraviolet lamp with substantial emission at 365 nm through the glass. After the glass was removed, the area of the layer and the weight were recorded. Coverage of the screen was calculated as 85 g/ft of phosphor.
The mean free path for 380 nm radiation was measured spectropho~ometrically as 304 microns.
The screen was used as a back screen with a 58 g/ft Gd202S:Tb (on a highly reflecting support) front screen tc make 70 kVp radiographs of a standard "bone and bead" test object with KODAK X-OMAT ~ x-ray film.
The control for the image quality evaluations was made with both front and back Gd202S:Tb screens. The speed of the control was 400 and the resolution was 2.24 lp/mm.
The transparen~ back screen gave a speed of 350 and a resolution of 2,24 lp/mm, The mottle of both radiographs was judged about equal, but the sharpness and bead visi-bility were superior in the transparent screen radiograph.
The invention has been described in detail withparticular reference to certain embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.
Another portion of the mixture was coated at di~erent thicknesses on a black anodized aluminum support as prepared in Preparation ~ and photopolymerized under glass cover shee's. Radiographs were made by exposing Lo-Dose~ film in contact with these experimental supported screens as back screens wlth 70 kVp x-rays. A control radiograph was ~ade by likewise exposing Lo-Dose~ film in contac-~ with a DuPont~ Par Speed Inténsifying screen in order to obtain the relative speeds of the experimental screens. The di~ference in speed was calculated through the known density vs. lo~ exposure curve ~or Lo~Dose~
film ~rom the densities which resulted on the exposed and developed rilms. The following results were obtained.
Screen ~^Xness Screer C~verage Relative Speed 10 micron lead (mi ron~? (g/~t ) PAR = 100* bar test o~ect Resolution 20 405 61 17~ 3.15 lp/m.r, 7~0 113 26~ 2.24-2.5 1115 15Q 325 2.0 *~ont~ ~r $~ee~ Intens~yi~ Screen Example 2 . . .
A mixture of 35.5 g o~ the thallium-activated rubidium iodide phosphor (.0004) as prepared in Prepara-tion 1 and 10 g o~ a 60:40 mixture of l-naphthyl carbinyl methacrylate and l-bromo-2-naphthylacrylate containing 0.3 percent 4,4'-bis-chloromethyl benzophenone was spread on a black anodized aluminum support and covered with a glass sheet while being photopolymerized. When polymeri-zation was complete, the glass sheet was released. The resulting transparent screen was 500 microns thick and had a coverage o~ 89 g of phosphor per square foot.
Radiographs made with this screen as a back screen with Lo-Dos Film at 70 kVp gave a relatlve radiographic speed tcalculated as in Example 1) of 255 compared to 285 ror a DuPont Hi-Plus~ Screen with Lo-Dose~ Film. When a bone and bead test object was employed in -the same comparison, better image quality was obtained with the transparent screen.
_ample 3 A mixture of 250 g of the thallium-activated rubidium iodide and 65 g of a 3:1 mixture of l-naphthyl carbinyl methacrylate and S-(l-naphthyl carbinyl) thioacr~la-te which also contained 0.3 percent by weight of 4,4'-bis-chloromethyl benzophenone was degassed under vacuum and then coated three ways: (1) on black anodized aluminum support, (2) on reflective aluminum support on an optically flat surface, and (3) on no support (self-supporting film). All three coatings were of equal thickness and were photopolymerized. Radiographs were made with these three screens, along with the DuPont Hi-Plus~
screen, using Lo~Dose~ Film, 70 k~p x-rays and a 20 ,u lead bar test object. The resolution of the radiographs was as follows:
Hi-Plus~ Screen 4.0 lp/mm Black Aluminum Support 4.0 lp/mm Reflective Aluminum Support 1.8 lp/mm Unsupported 1.8 lp/mm The resolution of the screen having a black support showed a dramatic increase both over the resolution of the screen having a reflective support and over that of the unsupported screen.
Example 4 A mixture of 136.8 g of thallium-activated rubidium iodide (.0004), 40.0 g of a 3:1 mixture of l-naphthyl carbinyl methacrylate containing up to 25 percent l-naphthyl carbinol and S~ naphthyl carbinyl) thioacrylate, and 0.3 percent by weight o~ 4,4'-bis-chloromethyl benzophenone was degassed under vacuum. The mixture was then coated on a support consisting of inlaid strips of black polished Formica~, black anodized aluminuzn, black Corning FotoEor glass having 80 percent of its area covered with holes, .005 inch in diameter and .015 inch deep, and dark blue ~.~'7~6~
-2~
tourmaline in a matrix of black Lucite~ plastic. The mixture was spread evenly across the support so thai the different types of support were coated with an equal thickness of the mi~ture. A glass cover sheet was placed on the mixture, and the mixture was photopolymerized. The cover sheet was removed, and the reflection optical densities of the dif~erent areas were measured. A 70 kVp radiograph of a 10 micron lead bar resolution test ob~ect was made using the screen as a back screen with DuPont Lo-Dos ~ film. The radiograph made using this transparent screen was compared with a control radiograph made with Lo-Dose~ film and using an opaque Hi-Plu ~ screen.
Radiographic speed was determined as in Example 1. The results obtained were as follows:
Refrac-tive Reflection Radiographic Resolution i5 Support Index nd_ optical Density Speed (lp/mn) Lucite~ 1.49 2.25 315 2.5-2.8 Fotofor ~
Glass - 1.87 250 3.15 tourmaline 1.64 2.57 250 3.15 20 Formica~ 1.65 2.17 245 3.15-3.55 Black anodized Aluminum 1.76 2.34 245 3.55 Hi-Plus~ Screen Control (opaque) - - 285 3.55 The results indicated that the optimum combination of speed and resolution were obtained when the fluoxescent composition mixture was coated on a black anodized aluminum surface for the particular transparent phosphor-polymer combination selected. Further, the results showed that the transparent screen having a black anodized aluminum support exhibited resolution equal to and radiographic speed nearly equal to the conYentional opaque control screen; however, the trans-parent screen of the invention displayed less quantum mottle than the conventional opaque screen.
Example 5 A mixture of 180 g of finely powdered Ba Sr 06FCl:Eu (.006) phosphor and 51 g of a blend of benzyl methacrylate and l~naphthylcarbinyl methacrylate ~approximately 50:50 by weight) was degassed under vacuum and spread on a black anodized aluminum support.
A glass cover sheet was placed on top of the layer and the mixture was polymerized by irradiation with an ultraviolet lamp with substantial emission at 365 nm through the glass. After the glass was removed, the area of the layer and the weight were recorded. Coverage of the screen was calculated as 85 g/ft of phosphor.
The mean free path for 380 nm radiation was measured spectropho~ometrically as 304 microns.
The screen was used as a back screen with a 58 g/ft Gd202S:Tb (on a highly reflecting support) front screen tc make 70 kVp radiographs of a standard "bone and bead" test object with KODAK X-OMAT ~ x-ray film.
The control for the image quality evaluations was made with both front and back Gd202S:Tb screens. The speed of the control was 400 and the resolution was 2.24 lp/mm.
The transparen~ back screen gave a speed of 350 and a resolution of 2,24 lp/mm, The mottle of both radiographs was judged about equal, but the sharpness and bead visi-bility were superior in the transparent screen radiograph.
The invention has been described in detail withparticular reference to certain embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.
Claims
1. A fluorescent composition comprising:
a) from 50 to 90 percent by weight of a substantially isotropic phosphor which is excited by x-rays and substantially transparent to light emitted by said phosphor; and b) from 10 to 50 percent by weight of a polymer having an index of refraction within .02 of the index of refraction of said phosphor over at least 80 percent of the emission spectrum of said phosphor, said polymer comprising:
i) from 5 to 99 mole percent of recurring units having the formula:
wherein R1 is H or alkyl; and R2 is alkyl, cycloalkyl, aryl, aralkyl or aryl substituted with alkyl, alkoxy, or heterocyclic; and ii) from 1 to 95 mole percent of recurring units having the formula:
wherein:
Ar is arylene;
R1 is H or alkyl;
R3 is H, alkyl, aryl, or aralkyl; and R4 is H, alkyl, alkoxy, amino, halogen, sulfide, sulfoxide, sulfonate or heterocyclic.
2. The fluorescent composition of claim 1 wherein said phosphor is an alkali metal compound.
3. The fluorescent composition of claim 1 wherein said phosphor is selected from the group consisting of RbI:Tl and KI:Tl.
4. A fluorescent coating composition comprising:
a) from 50 to 90 percent by weight of a substan-tially isotropic phosphor which is excited by x-rays and substantially transparent to light emitted by said phosphor; and b) from 10 to 50 percent by weight of a polymer having an index of refraction within .02 of the index of refraction of said phosphor over at least 80 per-cent of the emission spectrum of said phosphor, said polymer comprising:
i) from 5 to 99 mole percent of a polymerized co-polymerizable naphthyl carbinyl methacrylate monomer; and ii) from 1 to 95 mole percent of a polymerized co-polymerizable naphthyl carbinyl thioacrylate monomer.
5. The fluorescent composition of claim 4 wherein said phosphor is an alkali metal compound.
6. The fluorescent composition of claim 4 wherein said phosphor is selected from the group consisting of RbI:Tl and KI:Tl.
7. A fluorescent composition comprising:
a) from 50 to 90 percent by weight of a substantially isotropic alkali metal phosphor which is excited by x-rays and substantially transparent to light emitted by said phosphor; and b) from 10 to 50 percent by weight of a polymer having an index of refraction within .02 of the index of refraction of said phosphor over at least 80 percent of the emission spectrum of said phosphor, said polymer comprising:
i) from 5 to 99 mole percent of recurring units having the formula:
; and ii) from 1 to 95 mole percent of recurring units having the formula:
8. The fluorescent composition of claim 7 wherein said phosphor is selected from the group consisting of RbI:Tl and KI:Tl.
9. In an x-ray intensifying screen comprising a support having thereon a fluorescent composition comprising at least one substantially isotropic phosphor which is excited by x-rays and substantially transparent to light emitted by said phosphor in a polymer having an index of refraction within .02 of the index of refraction of said phosphor over at least 80 percent of the emission spectrum of said phosphor, and wherein said support has an index of refraction up to or equal to 0.05 units higher than the index of refraction of said phosphor and a reflection optical density of at least 1.7 to light emitted by said phosphor.
10. The x-ray intensifying screen of claim 9 wherein said phosphor is an alkali metal compound.
11. The x-ray intensifying screen of claim 10 wherein said phosphor is selected from the group consisting of RbI:.Tl and KI:Tl.
12. The x-ray intensifying screen of claim 9 wherein said support comprises a black anodized aluminum surface.
13. An x-ray intensifying screen comprising a support having thereon a fluorescent composition comprising:
a) from 50 to 90 percent by weight of a substan-tially isotropic phosphor which is excited by x-rays and substantially transparent to the light emitted by said phosphor; and b) from 10 to 50 percent by weight of a polymer having an index of refraction within .02 of the index of refraction of said phosphor over at least 80 percent of the emission spectrum of said phosphor, said polymer comprising:
i) from 5 to 100 mole percent of a polymerized copolymerizable ethylenically unsaturated monomer; and ii) from 0 to 95 mole percent of recurring units having the formula:
wherein:
Ar is arylene;
R1 is H or alkyl;
R3 is H, alkyl, aryl, or aralkyl; and R4 is H, alkyl, alkoxy, amino, halogen, sulfide, sulfoxide, sulfonate or heterocyclic;
said support having an index of refraction equal to or up to 0.05 units higher than the index of refraction of said phosphor, and having a reflection optical density of at least 1.7 to light emitted by said phosphor.
14. The x-ray intensifying screen of claim 13 wherein said phosphor is an alkali metal compound.
15. The x-ray intensifying screen of claim 14 wherein said phosphor is selected from the group consisting of RbI:Tl and KI:Tl.
16. The x-ray intensifying screen of claim 13 wherein said support comprises a black anodized aluminum surface.
17. An x-ray intensifying screen comprising a support having thereon a fluorescent composition comprising:
a) from 50 to 90 percent by weight of a substan-tially isotropic phosphor which is excited by x-rays and substantially transparent to the light emitted by said phosphor; and b) from 10 to 50 percent by weight of a polymer having an index of refraction within .02 of the index of refraction of said phosphor over at least 80 percent of the emission spectrum of the phosphor, said polymer comprising:
i) from 5 to 100 mole percent of recurring units having the formula:
wherein:
R1 is H or alkyl; and R2 is alkyl, cycloalkyl, aryl, aralkyl-or aryl substituted with alkyl, alkoxy or heterocyclic; and ii) from 0 to 95 mole percent of recurring units having the formula:
wherein:
Ar is arylene;
R1 is H or alkyl;
R3 is H, alkyl, aryl, or aralkyl; and R4 is H, alkyl, alkoxy, amino, halogen, sulfide, sulfoxide, sulfonate or heterocyclic;
said support having an index of refraction equal to or up to 0.05 units higher than the index of refraction of said phosphor, and having a reflection optical density of at least 1.7 to light emitted by said phosphor.
18. The x-ray intensifying screen of claim 17 wherein said phosphor is an alkali metal compound.
19. The x-ray intensifying screen of claim 18 wherein said phosphor is selected from the group consisting of RbI:Tl and KI:Tl.
20. The x-ray intensifying screen of claim 17 wherein said support comprises a black anodized aluminum surface.
21. An x-ray intensifying screen comprising a support having thereon a fluorescent composition comprising:
a) from 50 to 90 percent by weight of a substan-tially isotropic phosphor which is excited by x-rays and substantially transparent to light emitted by said phosphor; and b) from 10 to 50 percent by weight of a polymer having an index of refraction within .02 of the index of refraction of said phosphor over at least 80 percent of the emission spectrum of the phosphor, said polymer comprising:
i) from 5 to 100 mole percent of polymerzied co-polymerizable naphthyl carbinyl meth-acrylate monomer; and ii) from 0 to 95 mole percent of a polymerized copolymerizable naphthyl carbinyl thioacrylate monomer;
said support having an index of refraction equal to or up to 0.05 units higher than the index of refraction of said phosphor and having a reflection optical density of at least 1.7 to light emitted by said phosphor.
22. The x-ray intensifying screen of claim 21 wherein said phosphor is an alkali metal compound.
23. The x-ray intensifying screen of claim 22 wherein said phosphor is selected from the group consisting of RbI:Tl and KI:Tl.
24. The x-ray intensifying screen of claim 21 wherein said support comprises a black anodized aluminum surface.
25. An x-ray intensifying screen comprising a support having thereon a fluorescent composition comprising:
a) from 50 to 90 percent by weight of a substan-tially isotropic alkali metal phosphor which is excited by x-rays and substantially transparent to light emitted by said phosphor; and b) from 10 to 50 percent by weight of a polymer having an index of refraction without .02 of the index of refraction of said phosphor over at least 80 percent of the emission spectrum of said phosphor, said polymer comprising:
i) from 5 to 100 mole percent of a polymerized copolymerizable naphthyl carbinyl meth-acrylate monomer; and ii) from 0 to 95 mole percent of a polymerized copolymerizable naphthyl carbinyl thio-acrylate monomer;
said support comprising a black anodized aluminum surface having an index of refraction equal to or up to 0.05 units higher than the index of refraction of said phosphor and having a reflection optical density of at least 1.7 to light emitted by said phosphor.
26. The x-ray intensifying screen of claim 25 wherein said phosphor is selected from the group consisting of RbI:Tl and KI:Tl.
27. The x-ray intensifying screen of claim 25 wherein said naphthyl carbinyl methacrylate monomer is 1-naphthyl carbinyl methacrylate and wherein said naphthyl carbinyl thioacrylate monomer is S-(1-naphthyl carbinyl)-thioacrylate.
28. An x-ray intensifying screen comprising a support having thereon a fluorescent composition comprising:
a) from 50 to 90 percent by weight of a substantially isotropic alkali metal phosphor which is excited by x-rays and substantially transparent to light emitted by said phosphor, selected from the group consisting of RbI:Tl and KI:Tl; and b) from 10 to 50 percent by weight of a polymer having an index of refraction within .02 of the index of refraction of said phosphor over at least 80 percent of the emission spectrum of said phosphor, said polymer comprising:
i) from 5 to 100 mole percent of polymerized 1-naphthyl carbinyl methacrylate monomer; and ii) from 0 to 95 mole percent of polymerized S-(1-naphthyl carbinyl) thioacrylate monomer;
said support comprising a black anodized aluminum surface having an index of refraction equal to or up to 0.05 units higher than the index of refraction of said phosphor and having a reflection optical density of at least 1.7 to light emitted by said phosphor.
29. A process for making an x-ray intensifying screen comprising the steps of:
a) coating a mixture comprising:
i) from 50 to 90 percent by weight of a substantially isotopic phosphor which is excited by x-rays and substantially trans-parent to light emitted by said phosphor;
and ii) from 10 to 50 percent by weight of at least one copolymerizable monomer or mixture of monomers, said monomer or mixture of monomers, when polymerized, having an index of re-fraction within .02 of the index of refraction of said phosphor over at least 80 percent of the emission spectrum of said phosphor, on a support having an index of refraction equal to or up to 0.05 units higher than the index of refraction of said phosphor and having a reflection optical density of at least 1.7 to light emitted by said phosphor; and b) polymerizing said mixture coated on said support to produce a polymer comprising recurring units of said monomer or monomer mixture.
30. The process of claim 29 wherein said phosphor is an alkali metal compound.
31. The process of claim 30 wherein said phosphor is selected from the group consisting of RbI:Tl and KI:Tl.
32. The process of claim 29 wherein said support comprises a black anodized aluminum surface.
33. The process of claim 29 wherein said mixture further comprises from .001 to 1.0 percent of weight of a photoinitiator.
34. The process of claim 29 wherein said poly-merization step (b) is effected by irradiation with near-ultraviolet light.
35. A process for making an x-ray intensifying screen comprising the steps of:
a) coating a mixture comprising:
i) from 50 to 90 percent by weight of a substantially isotropic phosphor which is excited by x-rays and substantially trans-parent to light emitted by said phosphor; and ii) from 10 to 50 percent by weight of at least one copolymerizable monomer or mixture of monomers, said monomer or mixture of monomers, when polymerized, having an index of refraction within .02 of the index of refraction of said phosphor over at least 80 percent of the emission spectrum of said phosphor, said monomer or mixture of monomers comprising from 5 to 100 mole percent of a copolymerizable ethylenically unsaturated monomer, and from 0 to 95 mole percent of units having the formula:
wherein:
Ar is arylene;
R1 is H or alkyl;
R3 is H, alkyl, aryl, or aralkyl; and R4 is X, alkyl, alkoxy, amino, halogen, sulfide, sulfoxide, sulfonate or hetero-cyclic, on a support having an index of refraction equal to or up to 0.05 units higher than the index of refraction of said phosphor, and having a reflection optical density of at least 1.7 to light emitted by said phosphor; and b) polymerizing said mixture coated on said support to produce a polymer comprising recurring units of said monomeror monomer mixture.
35. The process of claim 35 wherein said phosphor is an alkali metal compound.
37. The process of claim 36 wherein said phosphor is selected from the group consisting of RbI:Tl and KI:Tl.
38. The process of claim 35 wherein said support comprises a black anodized aluminum surface.
39. The process of claim 35 wherein said poly-merization step (b) is effected by irradiation with near-ultraviolet light.
40. The process of claim 35 wherein said mixture further comprises from .001 to 1.0 percent by weight of a photoinitiator.
41. A process for making an X-ray intensifying screen comprising the steps of:
a) coating a mixture comprising:
i) from 50 to 90 percent by weight of a sub-stantially isotropic phosphor which is excited by x-rays and substantially trans-parent to light emitted by said phosphor;
and ii) from 10 to 50 percent by weight of at least one copolymerizable monomer or mixture of monomers, said monomer or mixture of monomers, when polymerized, having an index of refraction within .02 of the index of refraction of said phosphor over at least 80 percent of the emission spectrum of said phosphor, said monomer or mixture of monomers comprising from 5 to 100 mole percent of units having the formula:
wherein:
R1 is H or alkyl; and R2 is alkyl, cycloalkyl, aryl, aralkyl, or aryl substituted with alkyl, alkoxy or heterocyclic; and from 0 to 95 mole percent of units having the formula:
wherein:
Ar is arylene;
R1 is H or alkyl;
R3 is H, alkyl, aryl, or aralkyl; and R4 is H, alkyl, alkoxy, amino, halogen, sulfide, sulfoxide, sulfonate or heterocyclic;
on a support having an index of refraction equal to or up to 0.05 units higher than the index of refraction of said phosphor and having a reflection optical density of at least 1.7 to light emitted by said phosphor 7 and b) polymerizing said mixture coated on said support to produce a polymer comprising recurring units of said monomers or monomer mixture.
42. The process of claim 41 wherein said phosphor is an alkali metal compound.
43. The process of claim, 42 wherein said phosphor is selected from the group consisting of RbI:Tl and KI:Tl.
44. The process of claim 41 wherein said support comprises a black anodized aluminum surface.
45. The process of claim 41 wherein said poly-merization step (b) is effected by irradiation with near-ultraviolet light.
46. The process of claim 41 wherein said mixture further comprises from .001 to 1.0 percent by weight of a photoinitiator.
47. A process for making an x-ray intensifying screen comprising the steps of:
a) coating a mixture comprising:
i) from 50 to 90 percent by weight of a sub-stantially isotropic alkali metal phosphor which is excited by x-rays and substantially transparent to light emitted by said phosphor;
and ii) from 10 to 50 percent by weight of at least one copolymerizable monomer or mixture of monomers, said monomer or mixture of monomers, when polymerized, having an index of refrac-tion within .02 of the index of refraction of said phosphor over at least 80 percent of the emission spectrum of said phosphor, said monomer or mixture of monomers comprising from 5 to 100 mole percent of a naphthyl carbinyl methacrylate monomers and from 0 to 95 mole percent of a naphthyl carbinyl thioacrylate monomer; and iii) from .001 to 1.0 percent by weight of a photoinitiator;
on a support having an index of refraction equal to or up to 0.05 units higher than the index of refraction of said phosphor and having a reflection optical density of at least 1.7 to light emitted by said phosphor; and b) irradiating said mixture coated on said support with near-ultraviolet light.
48. The process of claim 47 wherein said phosphor is selected from the group consisting of RbI:Tl and XI:Tl.
49. The process of claim 47 wherein said support comprises a black anodized aluminum surface.
50. The process of claim 47 wherein said naphthyl carbinyl methacrylate monomer comprises 1-naphthyl carbinyl methacrylate and said naphthyl carbinyl thioacrylate mono-mer comprises S-(1-naphthyl carbinyl) thioacrylate.
51. The process of claim 47 wherein said photo-initiator is 4,4'-bis-chloromethyl benzophenone.
52. A process for making an x-ray intensifying screen comprising the steps of:
a) coating a mixture comprising:
i) from 50 to 90 percent by weight of a sub-stantially isotropic alkali metal phosphor which is excited by x-rays and substantially transparent to light emitted by said phosphor;
and ii) from 10 to 50 percent by weight of at least one copolymerizable monomer or mixture of monomers, said monomer or mixture of monomers;
when polymerized, having an index of re-fraction within .02 of the index of re-fraction of said phosphor over at least 80 percent of the emission spectrum of said phosphor, said monomer or mixture Or monomers comprising from 5 to 100 mole percent of 1-naphthyl carbinyl methacrylate and from 0 to 95 mole percent of S-(1-naphthyl carbinyl) thioacrylate; and iii) from .001 to 1.0 percent by weight of a photoinitiator, on a black anodized aluminum support having an index of refraction equal to or up to 0.05 units higher than the index of refraction of said phosphor and having a reflection optical density of at least 1.7 to light emitted by said phosphor;
and b) irradiating said mixture coated on said support with near-ultraviolet light.
53. The process of claim 52 wherein said photo-initiator is 4,4'-bis-chloromethyl benzophenone.
a) from 50 to 90 percent by weight of a substantially isotropic phosphor which is excited by x-rays and substantially transparent to light emitted by said phosphor; and b) from 10 to 50 percent by weight of a polymer having an index of refraction within .02 of the index of refraction of said phosphor over at least 80 percent of the emission spectrum of said phosphor, said polymer comprising:
i) from 5 to 99 mole percent of recurring units having the formula:
wherein R1 is H or alkyl; and R2 is alkyl, cycloalkyl, aryl, aralkyl or aryl substituted with alkyl, alkoxy, or heterocyclic; and ii) from 1 to 95 mole percent of recurring units having the formula:
wherein:
Ar is arylene;
R1 is H or alkyl;
R3 is H, alkyl, aryl, or aralkyl; and R4 is H, alkyl, alkoxy, amino, halogen, sulfide, sulfoxide, sulfonate or heterocyclic.
2. The fluorescent composition of claim 1 wherein said phosphor is an alkali metal compound.
3. The fluorescent composition of claim 1 wherein said phosphor is selected from the group consisting of RbI:Tl and KI:Tl.
4. A fluorescent coating composition comprising:
a) from 50 to 90 percent by weight of a substan-tially isotropic phosphor which is excited by x-rays and substantially transparent to light emitted by said phosphor; and b) from 10 to 50 percent by weight of a polymer having an index of refraction within .02 of the index of refraction of said phosphor over at least 80 per-cent of the emission spectrum of said phosphor, said polymer comprising:
i) from 5 to 99 mole percent of a polymerized co-polymerizable naphthyl carbinyl methacrylate monomer; and ii) from 1 to 95 mole percent of a polymerized co-polymerizable naphthyl carbinyl thioacrylate monomer.
5. The fluorescent composition of claim 4 wherein said phosphor is an alkali metal compound.
6. The fluorescent composition of claim 4 wherein said phosphor is selected from the group consisting of RbI:Tl and KI:Tl.
7. A fluorescent composition comprising:
a) from 50 to 90 percent by weight of a substantially isotropic alkali metal phosphor which is excited by x-rays and substantially transparent to light emitted by said phosphor; and b) from 10 to 50 percent by weight of a polymer having an index of refraction within .02 of the index of refraction of said phosphor over at least 80 percent of the emission spectrum of said phosphor, said polymer comprising:
i) from 5 to 99 mole percent of recurring units having the formula:
; and ii) from 1 to 95 mole percent of recurring units having the formula:
8. The fluorescent composition of claim 7 wherein said phosphor is selected from the group consisting of RbI:Tl and KI:Tl.
9. In an x-ray intensifying screen comprising a support having thereon a fluorescent composition comprising at least one substantially isotropic phosphor which is excited by x-rays and substantially transparent to light emitted by said phosphor in a polymer having an index of refraction within .02 of the index of refraction of said phosphor over at least 80 percent of the emission spectrum of said phosphor, and wherein said support has an index of refraction up to or equal to 0.05 units higher than the index of refraction of said phosphor and a reflection optical density of at least 1.7 to light emitted by said phosphor.
10. The x-ray intensifying screen of claim 9 wherein said phosphor is an alkali metal compound.
11. The x-ray intensifying screen of claim 10 wherein said phosphor is selected from the group consisting of RbI:.Tl and KI:Tl.
12. The x-ray intensifying screen of claim 9 wherein said support comprises a black anodized aluminum surface.
13. An x-ray intensifying screen comprising a support having thereon a fluorescent composition comprising:
a) from 50 to 90 percent by weight of a substan-tially isotropic phosphor which is excited by x-rays and substantially transparent to the light emitted by said phosphor; and b) from 10 to 50 percent by weight of a polymer having an index of refraction within .02 of the index of refraction of said phosphor over at least 80 percent of the emission spectrum of said phosphor, said polymer comprising:
i) from 5 to 100 mole percent of a polymerized copolymerizable ethylenically unsaturated monomer; and ii) from 0 to 95 mole percent of recurring units having the formula:
wherein:
Ar is arylene;
R1 is H or alkyl;
R3 is H, alkyl, aryl, or aralkyl; and R4 is H, alkyl, alkoxy, amino, halogen, sulfide, sulfoxide, sulfonate or heterocyclic;
said support having an index of refraction equal to or up to 0.05 units higher than the index of refraction of said phosphor, and having a reflection optical density of at least 1.7 to light emitted by said phosphor.
14. The x-ray intensifying screen of claim 13 wherein said phosphor is an alkali metal compound.
15. The x-ray intensifying screen of claim 14 wherein said phosphor is selected from the group consisting of RbI:Tl and KI:Tl.
16. The x-ray intensifying screen of claim 13 wherein said support comprises a black anodized aluminum surface.
17. An x-ray intensifying screen comprising a support having thereon a fluorescent composition comprising:
a) from 50 to 90 percent by weight of a substan-tially isotropic phosphor which is excited by x-rays and substantially transparent to the light emitted by said phosphor; and b) from 10 to 50 percent by weight of a polymer having an index of refraction within .02 of the index of refraction of said phosphor over at least 80 percent of the emission spectrum of the phosphor, said polymer comprising:
i) from 5 to 100 mole percent of recurring units having the formula:
wherein:
R1 is H or alkyl; and R2 is alkyl, cycloalkyl, aryl, aralkyl-or aryl substituted with alkyl, alkoxy or heterocyclic; and ii) from 0 to 95 mole percent of recurring units having the formula:
wherein:
Ar is arylene;
R1 is H or alkyl;
R3 is H, alkyl, aryl, or aralkyl; and R4 is H, alkyl, alkoxy, amino, halogen, sulfide, sulfoxide, sulfonate or heterocyclic;
said support having an index of refraction equal to or up to 0.05 units higher than the index of refraction of said phosphor, and having a reflection optical density of at least 1.7 to light emitted by said phosphor.
18. The x-ray intensifying screen of claim 17 wherein said phosphor is an alkali metal compound.
19. The x-ray intensifying screen of claim 18 wherein said phosphor is selected from the group consisting of RbI:Tl and KI:Tl.
20. The x-ray intensifying screen of claim 17 wherein said support comprises a black anodized aluminum surface.
21. An x-ray intensifying screen comprising a support having thereon a fluorescent composition comprising:
a) from 50 to 90 percent by weight of a substan-tially isotropic phosphor which is excited by x-rays and substantially transparent to light emitted by said phosphor; and b) from 10 to 50 percent by weight of a polymer having an index of refraction within .02 of the index of refraction of said phosphor over at least 80 percent of the emission spectrum of the phosphor, said polymer comprising:
i) from 5 to 100 mole percent of polymerzied co-polymerizable naphthyl carbinyl meth-acrylate monomer; and ii) from 0 to 95 mole percent of a polymerized copolymerizable naphthyl carbinyl thioacrylate monomer;
said support having an index of refraction equal to or up to 0.05 units higher than the index of refraction of said phosphor and having a reflection optical density of at least 1.7 to light emitted by said phosphor.
22. The x-ray intensifying screen of claim 21 wherein said phosphor is an alkali metal compound.
23. The x-ray intensifying screen of claim 22 wherein said phosphor is selected from the group consisting of RbI:Tl and KI:Tl.
24. The x-ray intensifying screen of claim 21 wherein said support comprises a black anodized aluminum surface.
25. An x-ray intensifying screen comprising a support having thereon a fluorescent composition comprising:
a) from 50 to 90 percent by weight of a substan-tially isotropic alkali metal phosphor which is excited by x-rays and substantially transparent to light emitted by said phosphor; and b) from 10 to 50 percent by weight of a polymer having an index of refraction without .02 of the index of refraction of said phosphor over at least 80 percent of the emission spectrum of said phosphor, said polymer comprising:
i) from 5 to 100 mole percent of a polymerized copolymerizable naphthyl carbinyl meth-acrylate monomer; and ii) from 0 to 95 mole percent of a polymerized copolymerizable naphthyl carbinyl thio-acrylate monomer;
said support comprising a black anodized aluminum surface having an index of refraction equal to or up to 0.05 units higher than the index of refraction of said phosphor and having a reflection optical density of at least 1.7 to light emitted by said phosphor.
26. The x-ray intensifying screen of claim 25 wherein said phosphor is selected from the group consisting of RbI:Tl and KI:Tl.
27. The x-ray intensifying screen of claim 25 wherein said naphthyl carbinyl methacrylate monomer is 1-naphthyl carbinyl methacrylate and wherein said naphthyl carbinyl thioacrylate monomer is S-(1-naphthyl carbinyl)-thioacrylate.
28. An x-ray intensifying screen comprising a support having thereon a fluorescent composition comprising:
a) from 50 to 90 percent by weight of a substantially isotropic alkali metal phosphor which is excited by x-rays and substantially transparent to light emitted by said phosphor, selected from the group consisting of RbI:Tl and KI:Tl; and b) from 10 to 50 percent by weight of a polymer having an index of refraction within .02 of the index of refraction of said phosphor over at least 80 percent of the emission spectrum of said phosphor, said polymer comprising:
i) from 5 to 100 mole percent of polymerized 1-naphthyl carbinyl methacrylate monomer; and ii) from 0 to 95 mole percent of polymerized S-(1-naphthyl carbinyl) thioacrylate monomer;
said support comprising a black anodized aluminum surface having an index of refraction equal to or up to 0.05 units higher than the index of refraction of said phosphor and having a reflection optical density of at least 1.7 to light emitted by said phosphor.
29. A process for making an x-ray intensifying screen comprising the steps of:
a) coating a mixture comprising:
i) from 50 to 90 percent by weight of a substantially isotopic phosphor which is excited by x-rays and substantially trans-parent to light emitted by said phosphor;
and ii) from 10 to 50 percent by weight of at least one copolymerizable monomer or mixture of monomers, said monomer or mixture of monomers, when polymerized, having an index of re-fraction within .02 of the index of refraction of said phosphor over at least 80 percent of the emission spectrum of said phosphor, on a support having an index of refraction equal to or up to 0.05 units higher than the index of refraction of said phosphor and having a reflection optical density of at least 1.7 to light emitted by said phosphor; and b) polymerizing said mixture coated on said support to produce a polymer comprising recurring units of said monomer or monomer mixture.
30. The process of claim 29 wherein said phosphor is an alkali metal compound.
31. The process of claim 30 wherein said phosphor is selected from the group consisting of RbI:Tl and KI:Tl.
32. The process of claim 29 wherein said support comprises a black anodized aluminum surface.
33. The process of claim 29 wherein said mixture further comprises from .001 to 1.0 percent of weight of a photoinitiator.
34. The process of claim 29 wherein said poly-merization step (b) is effected by irradiation with near-ultraviolet light.
35. A process for making an x-ray intensifying screen comprising the steps of:
a) coating a mixture comprising:
i) from 50 to 90 percent by weight of a substantially isotropic phosphor which is excited by x-rays and substantially trans-parent to light emitted by said phosphor; and ii) from 10 to 50 percent by weight of at least one copolymerizable monomer or mixture of monomers, said monomer or mixture of monomers, when polymerized, having an index of refraction within .02 of the index of refraction of said phosphor over at least 80 percent of the emission spectrum of said phosphor, said monomer or mixture of monomers comprising from 5 to 100 mole percent of a copolymerizable ethylenically unsaturated monomer, and from 0 to 95 mole percent of units having the formula:
wherein:
Ar is arylene;
R1 is H or alkyl;
R3 is H, alkyl, aryl, or aralkyl; and R4 is X, alkyl, alkoxy, amino, halogen, sulfide, sulfoxide, sulfonate or hetero-cyclic, on a support having an index of refraction equal to or up to 0.05 units higher than the index of refraction of said phosphor, and having a reflection optical density of at least 1.7 to light emitted by said phosphor; and b) polymerizing said mixture coated on said support to produce a polymer comprising recurring units of said monomeror monomer mixture.
35. The process of claim 35 wherein said phosphor is an alkali metal compound.
37. The process of claim 36 wherein said phosphor is selected from the group consisting of RbI:Tl and KI:Tl.
38. The process of claim 35 wherein said support comprises a black anodized aluminum surface.
39. The process of claim 35 wherein said poly-merization step (b) is effected by irradiation with near-ultraviolet light.
40. The process of claim 35 wherein said mixture further comprises from .001 to 1.0 percent by weight of a photoinitiator.
41. A process for making an X-ray intensifying screen comprising the steps of:
a) coating a mixture comprising:
i) from 50 to 90 percent by weight of a sub-stantially isotropic phosphor which is excited by x-rays and substantially trans-parent to light emitted by said phosphor;
and ii) from 10 to 50 percent by weight of at least one copolymerizable monomer or mixture of monomers, said monomer or mixture of monomers, when polymerized, having an index of refraction within .02 of the index of refraction of said phosphor over at least 80 percent of the emission spectrum of said phosphor, said monomer or mixture of monomers comprising from 5 to 100 mole percent of units having the formula:
wherein:
R1 is H or alkyl; and R2 is alkyl, cycloalkyl, aryl, aralkyl, or aryl substituted with alkyl, alkoxy or heterocyclic; and from 0 to 95 mole percent of units having the formula:
wherein:
Ar is arylene;
R1 is H or alkyl;
R3 is H, alkyl, aryl, or aralkyl; and R4 is H, alkyl, alkoxy, amino, halogen, sulfide, sulfoxide, sulfonate or heterocyclic;
on a support having an index of refraction equal to or up to 0.05 units higher than the index of refraction of said phosphor and having a reflection optical density of at least 1.7 to light emitted by said phosphor 7 and b) polymerizing said mixture coated on said support to produce a polymer comprising recurring units of said monomers or monomer mixture.
42. The process of claim 41 wherein said phosphor is an alkali metal compound.
43. The process of claim, 42 wherein said phosphor is selected from the group consisting of RbI:Tl and KI:Tl.
44. The process of claim 41 wherein said support comprises a black anodized aluminum surface.
45. The process of claim 41 wherein said poly-merization step (b) is effected by irradiation with near-ultraviolet light.
46. The process of claim 41 wherein said mixture further comprises from .001 to 1.0 percent by weight of a photoinitiator.
47. A process for making an x-ray intensifying screen comprising the steps of:
a) coating a mixture comprising:
i) from 50 to 90 percent by weight of a sub-stantially isotropic alkali metal phosphor which is excited by x-rays and substantially transparent to light emitted by said phosphor;
and ii) from 10 to 50 percent by weight of at least one copolymerizable monomer or mixture of monomers, said monomer or mixture of monomers, when polymerized, having an index of refrac-tion within .02 of the index of refraction of said phosphor over at least 80 percent of the emission spectrum of said phosphor, said monomer or mixture of monomers comprising from 5 to 100 mole percent of a naphthyl carbinyl methacrylate monomers and from 0 to 95 mole percent of a naphthyl carbinyl thioacrylate monomer; and iii) from .001 to 1.0 percent by weight of a photoinitiator;
on a support having an index of refraction equal to or up to 0.05 units higher than the index of refraction of said phosphor and having a reflection optical density of at least 1.7 to light emitted by said phosphor; and b) irradiating said mixture coated on said support with near-ultraviolet light.
48. The process of claim 47 wherein said phosphor is selected from the group consisting of RbI:Tl and XI:Tl.
49. The process of claim 47 wherein said support comprises a black anodized aluminum surface.
50. The process of claim 47 wherein said naphthyl carbinyl methacrylate monomer comprises 1-naphthyl carbinyl methacrylate and said naphthyl carbinyl thioacrylate mono-mer comprises S-(1-naphthyl carbinyl) thioacrylate.
51. The process of claim 47 wherein said photo-initiator is 4,4'-bis-chloromethyl benzophenone.
52. A process for making an x-ray intensifying screen comprising the steps of:
a) coating a mixture comprising:
i) from 50 to 90 percent by weight of a sub-stantially isotropic alkali metal phosphor which is excited by x-rays and substantially transparent to light emitted by said phosphor;
and ii) from 10 to 50 percent by weight of at least one copolymerizable monomer or mixture of monomers, said monomer or mixture of monomers;
when polymerized, having an index of re-fraction within .02 of the index of re-fraction of said phosphor over at least 80 percent of the emission spectrum of said phosphor, said monomer or mixture Or monomers comprising from 5 to 100 mole percent of 1-naphthyl carbinyl methacrylate and from 0 to 95 mole percent of S-(1-naphthyl carbinyl) thioacrylate; and iii) from .001 to 1.0 percent by weight of a photoinitiator, on a black anodized aluminum support having an index of refraction equal to or up to 0.05 units higher than the index of refraction of said phosphor and having a reflection optical density of at least 1.7 to light emitted by said phosphor;
and b) irradiating said mixture coated on said support with near-ultraviolet light.
53. The process of claim 52 wherein said photo-initiator is 4,4'-bis-chloromethyl benzophenone.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US23840481A | 1981-02-26 | 1981-02-26 | |
| US238,404 | 1981-02-26 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1175647A true CA1175647A (en) | 1984-10-09 |
Family
ID=22897750
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000393825A Expired CA1175647A (en) | 1981-02-26 | 1982-01-08 | Fluorescent compositions, x-ray intensifying screens, and processes for making same |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPS57159873A (en) |
| CA (1) | CA1175647A (en) |
| DE (1) | DE3206776A1 (en) |
| FR (1) | FR2500467B1 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4762998A (en) * | 1987-05-12 | 1988-08-09 | Eastman Kodak Company | Method for reading out an image signal stored in a transparent photostimulable phosphor |
| US4778995A (en) * | 1987-05-12 | 1988-10-18 | Eastman Kodak Company | Stimulable phosphor imaging apparatus |
| US4999505A (en) * | 1990-02-08 | 1991-03-12 | Eastman Kodak Company | Transparent radiation image storage panel |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0128384B1 (en) * | 1983-05-16 | 1989-09-20 | Fuji Photo Film Co., Ltd. | Radiation image storage panel |
| US4608301A (en) * | 1983-08-02 | 1986-08-26 | Fuji Photo Film Co., Ltd. | Radiographic intensifying screen |
| JPH0794659B2 (en) * | 1986-03-11 | 1995-10-11 | コニカ株式会社 | Radiation image conversion method and radiation image conversion panel used therefor |
| US5569485A (en) * | 1994-10-07 | 1996-10-29 | Minnesota Mining And Manufacturing Company | Method for the manufacture of a radiographic intensifying screen with antistat |
| US5411806A (en) * | 1994-10-07 | 1995-05-02 | Minnesota Mining And Manufacturing Company | Method for the manufacture of a phosphor screen and resulting article |
| DE19859880A1 (en) | 1998-12-23 | 2000-07-06 | Duerr Dental Gmbh Co Kg | Flat storage element for an X-ray image |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3023313A (en) * | 1958-10-13 | 1962-02-27 | Mallinckrodt Chemical Works | Method of making an X-ray image intensifying screen and resulting article |
| US3043710A (en) * | 1959-02-20 | 1962-07-10 | Du Pont | Fluorescent screens |
| GB1518613A (en) * | 1976-03-18 | 1978-07-19 | Agfa Gevaert | Radiographic intensifying screens |
| GB1587206A (en) * | 1977-05-06 | 1981-04-01 | Agfa Gevaert | Fuorescent x-ray image intensifying screen |
| JPS5923400B2 (en) * | 1979-06-07 | 1984-06-01 | 富士写真フイルム株式会社 | Radiographic image conversion panel |
-
1982
- 1982-01-08 CA CA000393825A patent/CA1175647A/en not_active Expired
- 1982-02-25 DE DE19823206776 patent/DE3206776A1/en not_active Ceased
- 1982-02-26 JP JP3044982A patent/JPS57159873A/en active Granted
- 1982-02-26 FR FR8203192A patent/FR2500467B1/fr not_active Expired
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4762998A (en) * | 1987-05-12 | 1988-08-09 | Eastman Kodak Company | Method for reading out an image signal stored in a transparent photostimulable phosphor |
| US4778995A (en) * | 1987-05-12 | 1988-10-18 | Eastman Kodak Company | Stimulable phosphor imaging apparatus |
| US4999505A (en) * | 1990-02-08 | 1991-03-12 | Eastman Kodak Company | Transparent radiation image storage panel |
Also Published As
| Publication number | Publication date |
|---|---|
| DE3206776A1 (en) | 1982-10-28 |
| JPS57159873A (en) | 1982-10-02 |
| FR2500467B1 (en) | 1983-12-23 |
| FR2500467A1 (en) | 1982-08-27 |
| JPH055873B2 (en) | 1993-01-25 |
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Legal Events
| Date | Code | Title | Description |
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| MKEC | Expiry (correction) | ||
| MKEX | Expiry |