Energy subtraction processing method for radiation images, stimulable phosphor sheet, stimulable phosphor sheet composite member and stimulable phosphor sheet-filter composite member used for the method

Claim 2

An energy subtraction processing method for radiation images comprising the steps of: i) exposing an object including a specific structure exhibiting radiation energy absorption characteristics different from the radiation energy absorption characteristics of the other structures to a radiation, ii) simultaneously exposing a plurality of stimulable phosphor sheets positioned in the condition overlaid one upon another in a composite member to the radiation passing through said object to have radiation images stored in the respective stimulable phosphor sheets so that image information containing, at the portion corresponding to said specific structure, the low energy component of the radiation in an amount smaller than the amount contained in the image information recorded in a stimulable phosphor sheet positioned closer to said object is recorded in a stimulable phosphor sheet positioned farther from said object, iii) scanning the respective stimulable phosphor sheets with stimulating rays to sequentially release the radiation energy stored in the stimulable phosphor sheets as light emission, iv) photoelectrically detecting the emitted light and converting it to digital image signals of the respective radiation images, v) on the basis of said radiation images converted to said digital image signals, obtaining at least two radiation images to be subtraction processed, and vi). extracting an image of said specific structure by conducting a subtraction processing of said digital image signals between the corresponding picture elements of said at least two radiation images to be subtraction processed.

Claim 3

A method as defined in Claim 1 wherein said composite member comprising a plurality of stimulable phosphor sheets comprises at least two stimulable phosphor sheets exhibiting different levels of characteristics of absorbing the low energy component of a radiation, said stimulable phosphor sheets being positioned in such a manner that a stimulable phosphor sheet exhibiting a higher level of characteristics of absorbing the low energy component of a radiation is closer to the object than a stimulable phosphor sheet exhibiting a lower level of said characteristics.

Claim 4

A method as defined in Claim 2 wherein said composite member comprises two stimulable phosphor sheets.

Claim 5

A method as defined in Claim 3 wherein different kinds of stimulable phosphors exhibiting different levels of characteristics of absorbing the low energy component of a radiation are used respectively in:said two stimulable phosphor sheets in such a manner that a stimulable phosphor exhibiting a higher level of said characteristics is used in the stimulable phosphor sheet positioned closer to the object, and a stimulable phosphor exhibiting a lower level of said characteristics is used in the stimulable phosphor sheet positioned farther from the object, whereby the level of said characteristics of the stimulable phosphor sheet positioned closer to the object is made higher than the level of said characteristics of the stimulable phosphor sheet positioned farther from the object.

Claim 6

A method as defined in Claim 3 wherein a material absorbing the low energy component of a radiation is dispersed in the stimulable phosphor layer of the stimulable phosphor sheet positioned closer to the object, whereby the level of characteristics of absorbing the low energy component of a radiation of the stimulable phosphor sheet positioned closer to the object is made higher than the level of said characteristics of the stimulable phosphor sheet positioned farther from the object.

Claim 7

A method as defined in Claim 3 wherein the stimulable phosphor sheet positioned closer to the object comprises a substrate and a stimulable phosphor layer provided thereon, and said substrate is made of a material absorbing the low energy component of a radiation, whereby the level of characteristics of absorbing the low energy component of a radiation of the stimulable phosphor sheet positioned closer to the object is made higher than the level of said characteristics of the stimulable phosphor sheet positioned farther from the object.

Claim 8

A method as defined in Claim 6 wherein said substrate is composed of said material absorbing the low energy component of a radiation, and another material for containing said material absorbing the low energy component of a radiation in the condition dispersed therein.

Claim 9

A method as defined in Claim 6 wherein said substrate is composed only of said material absorbing the low energy component of a radiation.

Claim 11

- 10. A method as defined in Claim 9 wherein said metal is at least one of Cu, W, Mo, Ni, Pb, Au, Ag, Ba, Ta, Fe, Al, Zn, Cd, Ti, Zr, V, Nb, Cr, Co, and Sn.

Claim 12

An energy subtraction processing method for radiation images comprising the steps of: i) exposing an object including a specific structure exhibiting radiation energy absorption characteristics different from the radiation energy absorption characteristics of the other structures to a radiation, ii) exposing a stimulable phosphor sheet-filter composite member comprising: a) a plurality of stimulable phosphor sheets positioned in the condition overlaid one upon another, and b) a filter made of a material absorbing the low energy component of the radiation and interposed . in at least one position between the respective stimulable phosphor sheets among a plurality of said stimulable phosphor sheets, to the radiation passing through said object to have radiation images stored in the respective stimulable phosphor sheets so that image information containing, at the portion corresponding to said specific structure, the low energy component of the radiation in an amount smaller than the amount contained in the image information recorded in a stimulable phosphor sheet positioned on the object side with respect to the position in which said filter is interposed is recorded in a stimulable phosphor sheet positioned on the. side opposite to said object with respect to the position in which said filter is interposed, iii) scanning the respective stimulable phosphor sheets with stimulating rays to sequentially release the radiation energy stored in the stimulable phosphor sheets as light emission, iv) photoelectrically detecting the emitted light and converting it to digital image signals of the respective radiation images, v) on the basis of the radiation image converted to said digital image signal which is obtained from a stimulable phosphor sheet positioned in each block of said stimulable phosphor sheet-filter composite member divided into blocks in a number equal to the number of the positions in which said filter is interposed plus one with respect to the position in which said filter is interposed, obtaining one radiation image to be subtraction processed from each of said blocks, thereby obtaining,the radiation images to be subtraction processed in a total number equal to the number of the positions in which said filter is interposed plus one, and vi) extracting an image of said specific structure by conducting a subtraction processing of said digital image signals between the corresponding picture elements of said radiation images to be subtraction processed.

Claim 13

An energy subtraction processing method for radiation images comprising the steps of: i) exposing an object including a specific structure exhibiting radiation energy absorption characteristics different from the radiation energy absorption characteristics of the other structures to a radiation, ii) exposing a stimulable phosphor sheet-filter composite member comprising: a) a plurality of stimulable phosphor sheets positioned in the condition overlaid one upon another, and b) a filter made of a material absorbing the low energy component of the radiation and interposed . in at least one position between the respective stimulable phosphor sheets among a plurality of said stimulable phosphor sheets, to the radiation passing through said object to have radiation images stored in the respective stimulable phosphor sheets so that image information containing, at the portion corresponding to said specific structure, the low energy component of the radiation in an amount smaller than the amount contained in the image information recorded in a stimulable phosphor sheet positioned on the object side with respect to the position in which said filter is interposed is recorded in a stimulable phosphor sheet positioned on the. side opposite to said object with respect to the position in which said filter is interposed, iii) scanning the respective stimulable phosphor sheets with stimulating rays to sequentially release the radiation energy stored in the stimulable phosphor sheets as light emission, iv) photoelectrically detecting the emitted light and converting it to digital image signals of the respective radiation images, v) on the basis of the radiation image converted to said digital image signal which is obtained from a stimulable phosphor sheet positioned in each block of said stimulable phosphor sheet-filter composite member divided into blocks in a number equal to the number of the positions in which said filter is interposed plus one with respect to the position in which said filter is interposed, obtaining one radiation image to be subtraction processed from each of said blocks, thereby obtaining,the radiation images to be subtraction processed in a total number equal to the number of the positions in which said filter is interposed plus one, and vi) extracting an image of said specific structure by conducting a subtraction processing of said digital image signals between the corresponding picture elements of said radiation images to be subtraction processed.

Claim 14

A method as defined in Claim 11 wherein said stimulable phosphor sheet-filter composite member comprises two stimulable phosphor sheets and said filter interposed therebetween.

Claim 15

A method as defined in Claim 11 wherein said stimulable phosphor sheet-filter composite member comprises three stimulable phosphor sheets and said filter interposed between the stimulable phosphor sheet positioned closest to the object and the middle stimulable phosphor sheet.

Claim 16

A method as defined in Claim 11 wherein said stimulable phosphor sheet-filter composite member comprises three stimulable phosphor sheets and two filters, each of -said filters being interposed between two adjacent stimulable phosphor sh-ets among said three stimulable phosphor sheets.

Claim 19

17 . A method as defined in any of Claims 11 to 16 wherein said material absorbing the low energy component of a radiation is a metal.

Claim 20

A method as defined in Claim 17 wherein said metal is at least one of Cu, W, Mo, Ni, Pb, Au, Ag, Ba, Ta, Fe, Al, Zn, Cd, Ti, Zr, V, Nb, Cr, Co, and Sn.

Claim 21

An energy subtraction processing method for radiation images comprising the steps of: i) exposing an object including a specific structure exposing an object including a specific structure exhibiting radiation energy absorption characteristics different from the- radiation energy absorption characteristics of the other structures to a radiation, ii) exposing a stimulable phosphor sheet comprising: a) a substrate made of a material absorbing the low energy component of the radiation, and b) two stimulable phosphor layers formed on opposite surfaces of said substrate, to the radiation passing through said object to have radiation images stored in the respective stimulable phosphor layers so that image information containing, at the portion corresponding to said specific structure, the low energy component of the radiation in an amount smaller than the amount contained in the image information recorded in the stimulable phosphor layer formed on the object side surface of said substrate of said stimulable phosphor sheet is-recorded in the stimulable phosphor layer formed on the substrate surface opposite to said object, iii) scanning the respective stimulable phosphor layers with stimulating rays to sequentially release the radiation energy stored in the stimulable phosphor layers as light emission, iv) photoelectrically detecting the emitted light and converting it to digital image signals of the respective radiation images, and v) extracting an image of said specific structure by conducting a subtraction processing of said digital image signals between the corresponding picture elements of the two radiation images converted to said digital image signals.

Claim 22

An energy subtraction processing method for radiation images comprising the steps of: i) exposing an object including a specific structure exposing an object including a specific structure exhibiting radiation energy absorption characteristics different from the- radiation energy absorption characteristics of the other structures to a radiation, ii) exposing a stimulable phosphor sheet comprising: a) a substrate made of a material absorbing the low energy component of the radiation, and b) two stimulable phosphor layers formed on opposite surfaces of said substrate, to the radiation passing through said object to have radiation images stored in the respective stimulable phosphor layers so that image information containing, at the portion corresponding to said specific structure, the low energy component of the radiation in an amount smaller than the amount contained in the image information recorded in the stimulable phosphor layer formed on the object side surface of said substrate of said stimulable phosphor sheet is-recorded in the stimulable phosphor layer formed on the substrate surface opposite to said object, iii) scanning the respective stimulable phosphor layers with stimulating rays to sequentially release the radiation energy stored in the stimulable phosphor layers as light emission, iv) photoelectrically detecting the emitted light and converting it to digital image signals of the respective radiation images, and v) extracting an image of said specific structure by conducting a subtraction processing of said digital image signals between the corresponding picture elements of the two radiation images converted to said digital image signals.

Claim 23

A method as defined in Claim 19 wherein said substrate is composed of said material absorbing the low energy component of a radiation, and another material for containing said material absorbing the low energy component of a radiation in the condition dispersed therein.

Claim 24

A method as defined in Claim 19 wherein said substrate is composed only of said material absorbing the low energy. component of a radiation.

Claim 26

23 . A method as defined in Claim 22 wherein said metal is at least one of Cu, W, Mo, Ni, Pb, Au, Ag, Ba, Ta, Fe, Al, Zn, Cd, Ti, Zr, V, Nb, Cr, Co, and Sn.

Claim 27

A stimulable phosphor sheet composite member for use in an energy subtraction processing method for radiation images, which comprises at least two kinds of stimulable phosphor sheets exhibiting different levels of characteristics of absorbing the low energy component of a radiation, said stimulable phosphor sheets being overlaid one upon another in the order of the higher (or lower) level of said characteristics. :

Claim 28

A stimulable phosphor sheet composite member for use in an energy subtraction processing method for radiation images, which comprises at least two kinds of stimulable phosphor sheets exhibiting different levels of characteristics of absorbing the low energy component of a radiation, said stimulable phosphor sheets being overlaid one upon another in the order of the higher (or lower) level of said characteristics. :

Claim 29

A composite member as defined in Claim 24 wherein said composite member comprises two stimulable phosphor sheets exhibiting different levels of said characteristics.

Claim 30

A composite member as defined in Claim 25 wherein different kinds of stimulable phosphors exhibiting different levels of said characteristics are used respectively in said two stimulable phosphor sheets, whereby the levels of said characteristics of said two stimulable phosphor sheets are made different from each other.

Claim 31

A composite member as defined in Claim 25 wherein a material absorbing the low energy component of a radiation is dispersed in the stimulable phosphor layer of one or the other of said two stimulable phosphor sheets, whereby the levels of said characteristics of said two stimulable phosphor sheets are made different from each other.

Claim 32

A composite member as defined in Claim 25 wherein one or the other of said two stimulable phosphor sheets comprises a substrate and a stimulable phosphor layer provided thereon, and said substrate is made of a material absorbing the low energy component of a radiation, whereby the levels of said characteristics of said two stimulable phosphor sheets are made different from each other.

Claim 33

A composite member as defined in Claim 28 wherein said substrate is composed of said material absorbing the low energy component of a radiation, and another material for containing said material absorbing the low energy component of a radiation in the condition dispersed therein.

Claim 34

A composite member as defined in Claim 28 wherein said substrate is composed only of said material absorbing the low energy component of a radiation.

Claim 35

A composite member as defined in any of Claims 27 to 30 wherein said material absorbing the low energy component of a radiation is a metal.

Claim 36

A composite member as defined in Claim 31 wherein said metal is at least one of Cu, W, Mo, Ni, Pb, Au, Ag, Ba, Ta, Fe, A1, Zn, Cd, Ti, Zr, V, Nb, Cr, Co and Sn.

Claim 37

A stimulable phosphor sheet-filter composite member for use in an energy subtraction processing method for radiation images, which comprises: a) a plurality of stimulable phosphor sheets positioned in the condition overlaid one upon another, and b) a filter made of a material absorbing the low energy component of a radiation and interposed in at least one position between the respective stimulable phsphor sheets among a plurality of said stimulable phosphor sheets.

Claim 38

A stimulable phosphor sheet-filter composite member for use in an energy subtraction processing method for radiation images, which comprises: a) a plurality of stimulable phosphor sheets positioned in the condition overlaid one upon another, and b) a filter made of a material absorbing the low energy component of a radiation and interposed in at least one position between the respective stimulable phsphor sheets among a plurality of said stimulable phosphor sheets.

Claim 39

A composite member as defined in Claim 33 wherein said composite member comprises two stimulable phosphor sheets and said filter interposed therebetween.

Claim 40

A composite member as defined in Claim 33 wherein said composite member comprises three stimulable phosphor sheets and said filter is interposed only in one position between any set of two adjacent stimulable phosphor sheets among said three stimulable phosphor sheets.

Claim 41

. A composite member as defined in Claim 33 wherein said composite member comprises three stimulable phosphor sheets and two filters, each of said filters being interposed between the two adjacent stimulable phosphor sheets among said three stimulable phosphor sheets.

Claim 42

A composite member as defined in any of Claims 33 to 36 wherein said filter is composed of said material absorbing the low energy component of a radiation, and another material for containing said material absorbing the low energy component of a radiation in the condition dispersed therein.

Claim 43

A composite member as defined in any of Claims 33 to 36 wherein said filter is composed only of said material absorbing the low energy component of a radiation.

Claim 44

A composite member as defined in any of Claims 33 to 38 wherein said material absorbing the low energy component of a radiation is a metal.

Claim 45

A composite member as defined in Claim 39 wherein said metal is at least one of Cu, W, Mo, Ni, Pb, Au, Ag, Ba, Ta, Fe, Al, Zn, Cd, Ti, Zr, V, Nb, Cr, Co and Sn.

Claim 46

A stimulable phosphor sheet for use in an energy subtraction processing method for radiation images, which comprises: a) a substrate made of a material absorbing the low energy component of a radiation, and b) stimulable phosphor layers formed on both surfaces of said substrate.

Claim 47

A stimulable phosphor sheet for use in an energy subtraction processing method for radiation images, which comprises: a) a substrate made of a material absorbing the low energy component of a radiation, and b) stimulable phosphor layers formed on both surfaces of said substrate.

Claim 48

A stimulable phosphor sheet as defined in Claim 41 wherein said substrate is composed of said material absorbing the low energy component of a radiation, and another material for containing said material absorbing the low energy component of a radiation in the condition dispersed therein.

Claim 49

A stimulable phosphor sheet as defined in Claim 41 wherein said substrate is composed only of said material absorbing the low energy component of a radiation.

Claim 50

A stimulable phosphor sheet as defined in any of Claims 41, 42 and 43 wherein said material absorbing the low energy component of a radiation is a metal.

Claim 51

A stimulable phosphor sheet as defined in Claim 44 wherein said metal is at least one of Cu, W, Mo, Ni, Pb, Au, Ag, Ba, Ta, Fe, A1, Zn, Cd, Ti, Zr, V, Nb, Cr, Co and Sn.