JP3726935B2 - Method and apparatus for acquiring image information for energy subtraction - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method and apparatus for acquiring image information for energy subtraction, and more particularly to a method and apparatus for acquiring image information for so-called two-shot energy subtraction, in which one type of image is obtained by two shootings. is there.
[0002]
[Prior art]
Reading a recorded radiation image to obtain an image signal, subjecting the image signal to appropriate image processing, and then reproducing and recording the image are performed in various fields. In addition, when the applicant of the present invention irradiates radiation (X-rays, α-rays, β-rays, γ-rays, electron beams, ultraviolet rays, etc.), a part of the radiation energy is accumulated, and when irradiated with excitation light such as visible light thereafter, it accumulates. Using a stimulable phosphor (stimulable phosphor) that exhibits photostimulated luminescence in response to the received energy, a radiation image of a subject such as a human body is once photographed and recorded on a sheet-like stimulable phosphor, and this accumulation is performed. The photosensitive phosphor sheet is scanned with excitation light such as laser light to produce stimulated emission light, and the obtained stimulated emission light is photoelectrically read to obtain image data. Based on this image data, a radiographic image of the subject Image recording / reproducing system that outputs a visible image on a recording material such as a photographic photosensitive material or a CRT has already been proposed (Japanese Patent Laid-Open Nos. 55-12429, 56-11395, 55-163472, 56-104645 and 55-116340).
[0003]
According to this system, it is possible to obtain a radiographic image having a wide latitude and excellent observation readability.
[0004]
Further, in the system using a radiation film, a stimulable phosphor sheet or the like as described above, after reading a plurality of recorded radiation images to obtain a plurality of image data, subtraction of the radiation image based on these image data Processing may be performed.
[0005]
Here, the subtraction processing of radiographic images refers to processing for obtaining an image corresponding to a difference between a plurality of radiographic images taken under different conditions. Specifically, the plurality of radiographic images are obtained at a predetermined sampling interval. A plurality of digital image data corresponding to each radiographic image is obtained by reading, and a subtraction process is performed for each corresponding sampling point (pixel) of the plurality of image data, whereby a specific subject portion (hereinafter referred to as a radiographic image) is obtained. , Which is also referred to as a shadow of a tissue or a structure).
[0006]
There are basically the following two types of subtraction processing. That is, by subtracting a radiographic image in which no contrast medium is injected from a radiographic image in which a specific part of the subject (for example, a shadow of a blood vessel or the like when the human body is used as a subject) is emphasized by injection of the contrast medium Using the so-called temporal subtraction to extract a specific part of a subject (shadows of blood vessels, etc.) and the fact that the specific part of the subject has different radiation absorption rates for radiation having different energy, On the other hand, radiations having different energies are irradiated to obtain a plurality of radiographic images of the respective radiations having different energies, and the plurality of radiographic images are appropriately weighted to calculate the difference (the following formula (1) And so-called energy subtraction to extract a specific part of the subject A.
[0007]
Sproc = Ka · H−Kb · L + Kc (1)
However, Sproc is subtraction image data obtained by subtraction processing, Ka and Kb are weighting coefficients, Kc is a bias component (hereinafter, Ka, Kb and Kc are collectively referred to as parameters of subtraction processing), and H is image data on the high-pressure side. , L means so-called low-pressure image data.
[0008]
There are also two types of energy subtraction processes. The first is a so-called two-shot energy subtraction process, and the other is a one-shot energy subtraction process.
[0009]
[Problems to be solved by the invention]
According to the two-shot method, a large energy difference between shots can be secured, so the range of image data obtained by subtraction processing is also large, and therefore the contrast of a reproduced image based on the subtraction signal is increased. Can do. However, in the two-shot method, image data obtained by two shootings must be accurately subtracted for each pixel, and the subject is a living body, particularly a chest image with a strong motion such as the heart, In practice, it was difficult to obtain two images having a temporal separation in which the positional relations matched with accuracy.
[0010]
On the other hand, in the one-shot method, two detectors are overlapped and image data is recorded in each of the two detectors in one shooting. At this time, an energy separation plate or the like is interposed between the two detectors. The image data recorded in both detectors can have different energy states while maintaining the positional relationship with high accuracy. However, in the one-shot method, a large energy difference between the two detectors cannot be secured, and it is difficult to increase the contrast of the subtraction reproduced image obtained because the range of the image data obtained by the subtraction process is small. Met.
[0011]
Thus, in the conventional energy subtraction process, both the one-shot method and the two-shot method have advantages and disadvantages.
[0012]
The present invention has been made in view of the above circumstances, and a method for acquiring image information for energy subtraction processing, in which a large energy difference between two pieces of image data is ensured and the overlay position accuracy is sufficiently secured in practice. And an object of the present invention.
[0013]
[Means for Solving the Problems]
In the method and apparatus for acquiring image information for energy subtraction according to the present invention, a so-called double-sided condensing phosphor sheet is first irradiated with high-pressure radiation to record high-pressure image information, and then immediately, Only the high-pressure image information recorded on the subject side (front side) part of the sheet is mainly erased so that the high-pressure image information recorded on the side opposite to the subject (back side) is not erased. Immediately irradiate low-pressure radiation and record low-pressure image information on the surface side of the sheet, minimizing the time interval between two shots and suppressing misalignment between the two image data. Moreover, by switching between high-pressure radiation and low-pressure radiation within a short period of time and recording image information separately, two energy subtractions with sufficient energy difference are secured. It is intended to obtain a use image information.
[0014]
That is, the method for acquiring image information for energy subtraction according to the present invention provides high-pressure image information corresponding to high-pressure radiation in which high-energy components are relatively emphasized and low-pressure radiation in which low-energy components are relatively emphasized for the same subject. A method for acquiring image information for energy subtraction that respectively acquires corresponding low-pressure image information,
The high-pressure radiation is applied to the subject, and high-pressure image information corresponding to the high-pressure radiation transmitted through the subject is emitted from both the front surface and the back surface facing the subject. Recorded on a stimulable phosphor sheet for condensing on both sides,
Erasing image information recorded mainly on the surface side portion of the stimulable phosphor sheet,
Next, the low-pressure radiation is irradiated onto the subject, and low-pressure image information corresponding to the low-pressure radiation transmitted through the subject is recorded on the stimulable phosphor sheet (mainly the front side portion of the sheet),
In the stimulable phosphor sheet, the low-pressure image information is obtained from the portion on the front surface side, and the high-pressure image information is obtained from the portion on the back surface side.
[0015]
Here, the storage phosphor sheet for double-sided light collection is only required to be able to individually read the image information recorded in one photographing from the front and back surfaces, and as a mode thereof, a transparent support A laminate in which one stimulable phosphor layer is laminated on the body, or a laminate having a stimulable phosphor layer on both sides so as to sandwich a predetermined support can be applied.
[0016]
In addition, the support in the stimulable phosphor sheet having a structure in which the stimulable phosphor layers are laminated on both sides of the support is desirably formed of a material that can absorb a low energy component. The material that can absorb the low energy component does not require a material that completely absorbs the low energy component, and may be any material that has a higher ratio of absorbing the low energy component than the high energy component. Further, between the two storage phosphor layers, in addition to the support, or as the support also serves as an intermediate layer having a property of easily transmitting excitation light and less erasing light. desirable. Furthermore, it is desirable that this intermediate layer has a characteristic that does not transmit stimulated emission light. This is because it is possible to prevent the mixed emission light, which is signal light, from being mixed between the two storage phosphor layers of the sheet.
[0017]
To acquire image information, specifically, an electrical signal is obtained by scanning a stimulable phosphor sheet with excitation light such as laser light and photoelectrically detecting stimulated emission light emitted from each scanning point. And so on.
[0018]
Further, the image information on the surface side portion of the sheet is erased by providing a flat erasing light source having a substantially uniform structure over the entire surface facing the surface of the stimulable phosphor sheet. May be emitted. In this case, the erasing light source can be an EL (electroluminescent) panel, erasing light and a flat light guide for guiding the erasing light. It is desirable that the thickness in the direction is also thin.
[0019]
As the radiation, a single predetermined radiation is used as the low-pressure radiation, and the predetermined radiation is transmitted through the low-pressure component absorbing member whose absorption rate for the low energy component is higher than that for the high energy component. One may be used as the high-pressure radiation, or the high-pressure radiation and the low-pressure radiation may be selectively switched and emitted from a single radiation source. In the type of obtaining high-pressure radiation by transmitting the low-pressure component absorption member, the high-pressure radiation is obtained by moving the low-pressure component absorption member between the radiation source and the subject at high speed in the very vicinity of the radiation source. And low-pressure radiation can be switched at high speed.
[0020]
Further, it is desirable to irradiate low-pressure radiation within 100 milliseconds after the irradiation of high-pressure radiation, and it is more desirable to irradiate low-pressure radiation within 50 milliseconds.
[0021]
Further, the phrase “erasing image information recorded mainly on the front side portion” means that image information recorded on the back side portion is not erased as much as possible.
[0022]
The above description also applies to the following inventions.
[0023]
The apparatus for acquiring image information for energy subtraction according to the present invention supports high-pressure image information corresponding to high-pressure radiation in which high-energy components are relatively emphasized and low-pressure radiation in which low-energy components are relatively emphasized for the same subject. An apparatus for acquiring image information for energy subtraction that respectively acquires low-pressure image information.
A radiation source capable of selectively switching between the high-pressure radiation and the low-pressure radiation; and
Accumulation for double-sided condensing that can detect light emission from both the front surface and the back surface of the object that are irradiated to the subject and receive radiation transmitted through the object. Fluorescent sheet,
The stimulable phosphor sheet is provided opposite to the surface and has a substantially uniform structure over the entire surface, and mainly emits erasing light for erasing image information recorded on the surface side portion. A flat erase light source;
The high-pressure radiation is emitted from the radiation source to record the high-pressure image information on the stimulable phosphor sheet, and then the erasing light is emitted from the erasing light source to be recorded mainly on the surface side portion. Next, the low-pressure radiation is emitted from the radiation source to record the low-pressure image information on the stimulable phosphor sheet (mainly the front side portion of the sheet), and the front side of the stimulable phosphor sheet Control means for obtaining the low-pressure image information from the portion and obtaining the high-pressure image information from the back side portion.
[0024]
The radiation source includes a radiation tube that emits a single radiation, and an absorptivity for the low energy component of the radiation that is provided between the tube and the subject so as to freely enter and exit the high energy component. Using a structure comprising a low-pressure component absorbing member having a higher absorption rate and driving means for driving the low-pressure component absorbing member between the tube and the subject in accordance with a predetermined instruction signal. Alternatively, a single radiation tube that can be emitted by switching between high-pressure radiation and low-pressure radiation according to a predetermined instruction signal may be used.
[0025]
The time from the high-pressure radiation irradiation to the low-pressure radiation irradiation by the control means is preferably within 100 milliseconds, and more preferably within 50 milliseconds.
[0026]
【The invention's effect】
According to the method and apparatus for acquiring image information for energy subtraction according to the present invention, a high-pressure image information is first recorded by first irradiating a so-called double-sided condensing phosphor sheet with high-pressure radiation. In order to prevent the high-pressure image information recorded on the back side portion of the sheet from being erased, only the image information recorded on the front-side portion of the sheet is erased, and the low-pressure radiation is immediately irradiated to obtain the low-pressure image information on the sheet (mainly the sheet By recording on the front side), the time interval between the two shots is minimized, the positional deviation between the two image data is suppressed, and the high-pressure radiation and the low-pressure radiation are selectively used. Two pieces of energy subtraction image information with sufficient difference can be obtained.
[0027]
Therefore, it is possible to suppress the generation of noise due to positional deviation and obtain a high-contrast, high-quality energy subtraction image by improving energy separation.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, specific embodiments of an image information acquisition apparatus for energy subtraction according to the present invention will be described with reference to the drawings.
[0029]
FIG. 1 is a schematic diagram showing an embodiment of a radiographic image capturing apparatus as an image information acquiring apparatus for energy subtraction according to the present invention.
[0030]
Acquisition device energy subtraction image information shown is for one subject 50, high energy image information S _H and the low energy component corresponding to the high-pressure radiation L _H high energy component is relatively emphasized is emphasized relatively radiation a acquisition device energy subtraction image information for each acquires the low energy image information S _L, which can emit a high radiation L _H and the low-pressure radiation L _L selectively switched corresponding to the low-pressure radiation L _L was Both sides of the source 10 and a support 23 made of a material capable of absorbing the low energy component of the irradiated radiation L, disposed at a position where the subject 50 is irradiated and the radiation L ′ transmitted through the subject 50 is received. Are provided opposite to the stimulable phosphor layer 21 on the subject 50 side of the stimulable phosphor sheet 20 and the stimulable phosphor sheet 20, respectively. The EL panel 30 that has a substantially uniform structure over the entire surface and emits erasing light K that mainly erases image information recorded on the storage phosphor layer 21 on the subject 50 side, and radiation first source 10 brought record high energy image information S _H on both stimulable phosphor layer 21, 22 by emitting a high-pressure radiation L _H stimulable phosphor sheet 20 from and then allowed to emit erasing light K from the erase light source 30 mainly erase the recorded image information (high energy image information) S _H to the stimulable phosphor layer 21 of the object 50 side, then, from the radiation source 10 to emit the low radiation L _L of the stimulable phosphor sheet 20 subjects The low-pressure image information S _L is recorded on the 50-side stimulable phosphor layer 21, the low-pressure image information S _L is acquired from the stimulable phosphor layer 21 on the subject 50 side of the stimulable phosphor sheet 20, and the subject 50 control for acquiring high energy image information S _H from the stimulable phosphor layer 22 of the opposite side of The control means 40 is provided.
[0031]
Wherein said radiation source 10, more specifically the radiation tube 11 for emitting a single type of radiation L _0, provided freely in and out between the tube 11 and the object 50, the radiation L ₀ The low-pressure component absorbing member 12 whose absorption rate for the low energy component is higher than the absorption rate for the high energy component, and a drive for driving the low-pressure component absorbing member 12 between the tube 11 and the subject 50 in accordance with a predetermined instruction signal And means 13.
[0032]
In this embodiment, the tube voltage of the radiation tube 11 is 100 kV, and a 1 mm thick Cu (copper) filter is used as the low-pressure component absorbing member 12.
[0033]
Since the Cu filter 12 is provided in the immediate vicinity of the radiation tube 11, the size of the filter 12 for irradiating the entire sheet 20 with the radiation (high-pressure radiation) L _H through the filter 12 is accumulative. It may be very small compared to the phosphor sheet 20, and the amount of movement that must be moved to retract the filter 12 from between the tube 11 and the subject 50 is small and should be completed in about 10 milliseconds. Can do.
[0034]
Further, the emission time of the erasing light K for the EL panel 30 to erase the image information recorded on the stimulable phosphor layer 21 on the subject 50 side is 50 milliseconds.
[0035]
The time from the irradiation of the high-pressure radiation L _{H to} the irradiation of the low-pressure radiation L _L by the control means 40 is controlled within 100 milliseconds.
[0036]
Next, the operation of the image information acquisition apparatus for energy subtraction according to the present embodiment will be described.
[0037]
First, a radiation L ₀ having a tube voltage of 100 kV is emitted from the radiation tube 11 through the Cu filter 12 for a short time toward the subject 50 disposed on the stimulable phosphor sheet 20 through the EL panel 30. The emitted radiation L ₀ is attenuated in the low energy component while passing through the Cu filter 12 and becomes the high pressure radiation L _H in which the relatively high energy component is emphasized, and the high pressure radiation L _H passes through the subject 50. The transmitted radiation L _H passes through the EL panel 30 and enters the stimulable phosphor sheet 20.
[0038]
Here, the transmitted radiation L _H incident on the stimulable phosphor sheet 20 is first incident on the stimulable phosphor layer 21 on the side close to the subject 50, and a relatively high energy component is incident on the stimulable phosphor layer 21. The high-pressure image information S _H of the subject emphasized is accumulated and recorded, and the transmitted radiation L _H is further attenuated in the low energy component while passing through the support 23, and the high energy component in which the higher energy component is emphasized. 'is a, high-pressure radiation L _H' L _H is incident on the stimulable phosphor layer 22 on the side far from the object 50, in the stimulable phosphor layer 22, of the subject higher energy component is emphasized High-pressure image information S _H ′ is accumulated and recorded.
[0039]
Immediately after this shooting is performed, specifically, within about 10 milliseconds after shooting, the driving means 13 is moved between the tube 11 and the subject 50 by the control action of the control means 40, the Cu filter 12 Move to evacuate.
[0040]
On the other hand, the EL panel 30 emits light by the control action of the control means 40 within 50 milliseconds immediately after photographing, and the high-pressure image information accumulated and recorded in the stimulable phosphor layer 21 on the side close to the subject 50 by this light emission. _SH is erased. However, this erasing does not need to be as strong as the storable phosphor sheet is reused, and it is sufficient if the high-pressure component is erased to some extent.
[0041]
Immediately after this erasure is made, specifically, within 100 milliseconds after the first image is taken, toward the subject 50 disposed on the stimulable phosphor sheet 20 via the EL panel 30, The radiation L ₀ with a tube voltage of 100 kV is emitted from the radiation tube 11 without passing through the Cu filter 12 for a short time. Since the emitted radiation L ₀ does not pass through the Cu filter 12, the low energy component is not attenuated as in the first imaging, and therefore, the low energy component is emphasized relative to the first imaging. is a low pressure radiation L _L (= L _0), the low-pressure radiation L _L irradiates the object 50, the transmitted radiation L _L is incident on the transmission to the stimulable phosphor sheet 20 EL panel 30.
[0042]
Here, the transmitted radiation L _L incident on the stimulable phosphor sheet 20 is first incident on the stimulable phosphor layer 21 on the side close to the subject 50, and a relatively low energy component enters the stimulable phosphor layer 21. The low-pressure image information S _L of the subject emphasized is accumulated and recorded, and the transmitted radiation L _L ′ attenuates the low energy component while passing through the support 23, and the relatively high energy component is emphasized. "is a, high-pressure radiation L _H" high radiation L _H is incident on the stimulable phosphor layer 22 on the side far from the object 50, in the stimulable phosphor layer 22, relatively high energy component is emphasized The high-pressure image information S _H ″ of the subject is stored and recorded.
[0043]
Here, on the side of the stimulable phosphor layer 21 closer to the subject 50, in terms of high energy image information S _H recorded in first imaging has been erased, the low energy image information S _L at the second-shooting recording will be made, in the end, in a state of low image information S _L is recorded.
[0044]
On the other hand, in the stimulable phosphor layer 22 on the side far from the subject 50, in addition to the high-pressure image information S _H ′ recorded in the first shooting, the high-pressure image information S _H ″ is recorded in the second shooting. As a result, the high-pressure image information S _H ′ and S _H ″ are finally recorded.
[0045]
Therefore, by reading out the image information separately from both sides 21 and 22 of these sheets 20, the energy separation from this sheet 20 is sufficient to the extent that the conventional one-shot method suitable for energy subtraction processing could not be obtained. The low-pressure image information S _L and the high-pressure image information S _H ′, S _H ″ thus obtained can be acquired.
[0046]
In addition, high-pressure radiation is irradiated to record high-pressure image information, and then immediately, the high-pressure image information recorded on the stimulable phosphor layer on the side opposite to the subject of the sheet is not erased. By erasing only the image information recorded on the stimulable phosphor layer, and immediately irradiating the low-pressure radiation to record the low-pressure image information on the stimulable phosphor layer on the subject side of the sheet, the conventional two-shot method In this case, image data for energy subtraction processing can be obtained in such a short time that it could not be acquired. Therefore, a positional shift between the two image data can be sufficiently suppressed.
[0047]
As described above, according to the energy subtraction image information acquisition apparatus of the present embodiment, the energy subtraction image information suppresses the positional deviation to a degree that cannot be acquired by the conventional two-shot method, and the conventional one-shot image information is obtained. Since image information with sufficient energy separation that could not be acquired by the law can be obtained, the energy subtraction image reproduced based on the image information acquired in this way is positioned as compared with the conventional one. Noise due to deviation is sufficiently suppressed and has sufficient contrast, and the image quality of the energy subtraction image can be improved.
[0048]
In the present embodiment, the high-pressure radiation L _H and the low-pressure radiation L _L are combined with a radiation tube that emits a single radiation, and a radiation tube that is provided between the tube and the subject. It comprises a low-pressure component absorbing member whose absorption rate for low energy components is higher than that for high energy components, and driving means for driving the low-pressure component absorbing member between the tube and the subject in accordance with a predetermined instruction signal. Although the aspect which was supposed to be output from the radiation source has been shown, the image information acquisition apparatus for energy subtraction according to the present invention is not limited to this aspect. For example, high-pressure radiation and low-pressure radiation are output according to a predetermined instruction signal. A radiation source consisting of a single radiation tube that can be switched and emitted may be used, or only a high-pressure radiation source that emits only high-pressure radiation and a low-pressure radiation. It is good also as a structure using two with the low-pressure radiation source to do.
[0049]
Further, as the low-pressure component absorbing member, it is possible to apply a member other than a Cu filter, and the above-described EL panel is the only means for erasing image information recorded on the storage phosphor layer on the subject side. Alternatively, it is possible to use an erasing light and a flat light guide that guides the erasing light.
[0050]
Furthermore, as the stimulable phosphor sheet for double-sided condensing, any storage information can be used as long as it can individually read image information recorded in one shooting from the front and back surfaces, and is applied in the above-described embodiment. Further, the present invention is not limited to the structure having the stimulable phosphor layers 21 and 22 on both surfaces of the support 23, and for example, a laminate in which one stimulable phosphor layer is laminated on a transparent support is also applicable. be able to.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing an embodiment of an apparatus for acquiring image information for energy subtraction according to the present invention.
10 Radiation source
11 tube
12 Cu filter
13 Drive means
20 Storage phosphor sheet
21,22 Storage phosphor layer
23 Support
30 EL panel
40 Control means
50 Subject L _L Low pressure radiation L _H High pressure radiation

Claims (7)

Energy subtraction images for acquiring high-pressure image information corresponding to high-pressure radiation with relatively emphasized high-energy components and low-pressure image information corresponding to low-pressure radiation with relatively emphasized low-energy components for the same subject. A method for obtaining information,
By irradiating the subject with the high-pressure radiation, the high-pressure image information corresponding to the high-pressure radiation transmitted through the subject can be detected from both the front surface and the back surface of the subject. Record on the stimulable phosphor sheet for condensing on both sides,
Erasing light is emitted from a flat erasing light source having a substantially uniform structure over the entire surface of the stimulable phosphor sheet, which is provided facing the surface. Erase the image information recorded on the surface side part,
Next, the low-pressure radiation is applied to the subject, and low-pressure image information corresponding to the low-pressure radiation transmitted through the subject is recorded on the stimulable phosphor sheet,
A method of acquiring energy subtraction image information, wherein the low-pressure image information is acquired from the front side portion of the stimulable phosphor sheet, and the high-pressure image information is acquired from the back side portion. Using predetermined radiation as the low-pressure radiation, and using the predetermined radiation transmitted through the low-pressure component absorbing member having an absorption rate for a low energy component higher than that for a high energy component as the high-pressure radiation. method of obtaining the energy subtraction image information according to claim 1 Symbol mounting characterized. From the high-pressure radiation and extractable single radiation source by switching between low-pressure radiation, the method obtains of claim 1 Symbol placement energy subtraction image information, characterized in that it allowed to selectively emit the high radiation or low radiation . Method of obtaining the energy subtraction image information according to the 3 had Zureka 1 paragraphs 請 Motomeko 1 you and performs irradiation of the low-pressure radiation within 100 milliseconds after the irradiation of the high-pressure radiation. Energy subtraction images for acquiring high-pressure image information corresponding to high-pressure radiation with relatively emphasized high-energy components and low-pressure image information corresponding to low-pressure radiation with relatively emphasized low-energy components for the same subject. An information acquisition device,
A radiation tube that emits a single radiation, and a low pressure that is provided between the tube and the subject so as to freely enter and exit the low energy component of the radiation and has a higher absorption rate than the high energy component. The high-pressure radiation and the low-pressure radiation are selectively provided, comprising: a component absorbing member; and a driving unit that drives the low-pressure component absorbing member into and out of the tube and the subject according to a predetermined instruction signal. A radiation source that can be switched to
Accumulation for double-sided condensing that can detect light emission from both the front surface and the back surface of the object that are irradiated to the subject and receive radiation transmitted through the object. Fluorescent sheet,
The stimulable phosphor sheet is provided opposite to the surface and has a substantially uniform structure over the entire surface, and mainly emits erasing light for erasing image information recorded on the surface side portion. A flat erase light source;
The high-pressure radiation is emitted from the radiation source to record the high-pressure image information on the stimulable phosphor sheet, and then the erasing light is emitted from the erasing light source to be recorded mainly on the surface side portion. Then, the low-pressure radiation is emitted from the radiation source to record the low-pressure image information on the stimulable phosphor sheet, and the low-pressure image information from the surface-side portion of the stimulable phosphor sheet. And a control means for performing control for acquiring the high-pressure image information from the back side portion. Energy subtraction images for acquiring high-pressure image information corresponding to high-pressure radiation with relatively emphasized high-energy components and low-pressure image information corresponding to low-pressure radiation with relatively emphasized low-energy components for the same subject. An information acquisition device,
A radiation source consisting of a single radiation tube capable of switching and emitting the high-pressure radiation and the low-pressure radiation according to a predetermined instruction signal ;
Accumulation for double-sided condensing that can detect light emission from both the front surface and the back surface of the object that are irradiated to the subject and receive radiation transmitted through the object. Fluorescent sheet,
The stimulable phosphor sheet is provided opposite to the surface and has a substantially uniform structure over the entire surface, and mainly emits erasing light for erasing image information recorded on the surface side portion. A flat erase light source;
The high-pressure radiation is emitted from the radiation source to record the high-pressure image information on the stimulable phosphor sheet, and then the erasing light is emitted from the erasing light source to be recorded mainly on the surface side portion. Then, the low-pressure radiation is emitted from the radiation source to record the low-pressure image information on the stimulable phosphor sheet, and the low-pressure image information from the surface-side portion of the stimulable phosphor sheet. And a control means for performing control for acquiring the high-pressure image information from the back side portion. The apparatus for acquiring image information for energy subtraction according to claim 5 or 6 , wherein a time from the irradiation of the high-pressure radiation to the irradiation of the low-pressure radiation by the control means is set within 100 milliseconds.

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