JPH01178955A - Radiographic information recorder/reader - Google Patents

Abstract

PURPOSE:To quickly carry out energy subtraction by extracting only a part of a structure in an image out of image information obtained by accumulating and recording radiograph information on an accumulating phosphor layer and obtaining an image signal to be displayed. CONSTITUTION:First and second accumulating phosphor layers 26A and 26B are formed on one surface and the other of a flexible belt 26 acting as a radio active energy converting filter, whereby radiographic information for subtraction can be recorded (photographed) simultaneously on those layers. The accumulat ing phosphor layers 26A and 26B are provided with image reading parts 57 respectively: therefore radiograph information accumulated and recorded on the layers can be read out in parallel. Thus, subtraction can be carried out quickly, and especially the efficiency of diagnostic operation in a mass diagnosis can be improved considerably.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention accumulates and records radiation image information in a layer of stimulable phosphor, then irradiates this with excitation light, and responds to the accumulated and recorded image information. It relates to a radiation image information recording/reading device that detects light emitted by stimulated luminescence and reads image information as an electrical image signal. The present invention relates to a radiographic image information recording/reading device that can be used to record and read radiation image information.

(Prior art) When a certain type of phosphor is irradiated with radiation (X-rays, α-rays, β-rays, γ-rays, ultraviolet rays, electron beams, etc.), part of the energy of this radiation is accumulated in the phosphor. Then, when the phosphor is irradiated with excitation light such as visible light, the phosphor exhibits stimulated luminescence depending on the accumulated energy. A phosphor exhibiting such properties is called a stimulable phosphor (stimulable phosphor).

Using this stimulable phosphor, radiation image information of a subject such as a human body is recorded on a stimulable phosphor sheet (hereinafter referred to as a stimulable phosphor sheet), which is then scanned with excitation light and illuminated. A method has been proposed in which the stimulated emitted light is photoelectrically read to obtain an image signal, and the image signal is processed to obtain a radiographic image of a subject that is suitable for diagnosis (for example, Japanese Patent Application Laid-Open No. 1983-1981). No. 12429, No. 55-116340, No. 55-163472, No. 56-11395, No. 56-104645, etc.). This final image can be reproduced as a hard copy or on a CRT. In any case, in such a radiation image information recording and reproducing method, the stimulable phosphor sheet does not ultimately record image information, but temporarily stores image information in order to provide an image to the final recording medium as described above. Therefore, this stimulable phosphor sheet may be used repeatedly, and such repeated use is extremely economical.

In order to reuse the stimulable phosphor sheet as described above, the radiation energy remaining in the stimulable phosphor sheet after the stimulated luminescence light has been read can be absorbed by, for example,
As shown in No. 2, No. 56-12599, residual radiation images may be erased by irradiating the sheet with light or heat, and the stimulable phosphor sheet may be used again for recording radiation images.

On the other hand, subtraction processing of radiographic images has been conventionally known. This radiographic image subtraction is a process in which two radiographic images taken under different conditions are photoelectrically read out to obtain digital image signals, and then these digital image signals are subtracted by matching each pixel of both images. , is a method of obtaining a difference signal that extracts a specific structure in a radiographic image, and if the difference signal obtained in this way is used,
It is possible to reproduce a radiographic image in which only specific structures are extracted.

There are basically two methods for this subtraction process: That is, a specific structure is extracted by subtracting (subtracting) the image signal of a radiographic image in which no contrast medium has been injected from the image signal No. 7 of a radiographic image in which a specific structure has been emphasized by contrast medium injection. So-called temporal subtraction processing is used to irradiate the same subject with radiation having different energy distributions, or to change the energy distribution state of the radiation after passing through the subject.
The radiation is applied to two radiation detection means, thereby creating an image in which a specific structure differs between the two radiation images, and then subtracting (subtracting) the image signals of these two radiation images with appropriate weighting. ) to extract an image of a specific structure.

Since this subtraction processing is an extremely effective method, especially in medical diagnosis, it has attracted much attention in recent years, and its research and development are actively progressing by making full use of electronic engineering technology.

In the radiation image information recording and reproducing system using the stimulable phosphor sheet described above, the radiation image information recorded on the sheet is directly read in the form of an electrical image signal, so according to this system, It becomes possible to perform the above-mentioned subtraction treatment on the container. When performing energy subtraction processing using this stimulable phosphor sheet, if a radiation energy conversion filter made of a copper plate or the like is placed between two stimulable phosphor sheets, for example, the radiation transmitted through the subject can be By irradiating these two sheets simultaneously, images with different specific structures can be recorded on both sheets (so-called one-shot energy subtraction).

Therefore, in order to actually perform this one-shot energy subtraction processing, radiation image information recording (
The photographing) device is configured to record (photograph) radiation image information by arranging two stimulable phosphor sheets and an energy conversion filter as described above, and after recording the radiation image information. For the two stimulable phosphor sheets, reading processing similar to normal reading processing is sequentially performed to obtain two sets of image signals.

(Problem to be Solved by the Invention) However, if two stimulable phosphor sheets are sequentially read as described above, the time required for the reading process will naturally increase, so this is not practical, especially during mass medical examinations. It was difficult to perform energy subtraction as described above.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a radiation image information recording/reading apparatus that can quickly perform the above-mentioned energy subtraction using a stimulable phosphor.

(Means and effects for solving the problems) The radiation image information recording/reading device of the present invention includes a layer of stimulable phosphor as described above, one surface of the belt having the function of converting radiation energy, They are placed on the ground surface, and each specific structure receives two different radiation image information with one radiation exposure.
The stimulable phosphor layer records information on each of the two stimulable phosphor layers, and also includes an image reading unit that reads radiation image information stored and recorded in the stimulable phosphor layer, and erases residual radiation images on the stimulable phosphor layer as described above. It is characterized in that an erasing section is provided for each of the two stimulable phosphor layers so that two pieces of radiation image information can be read simultaneously in parallel.More specifically, the above-mentioned a band-shaped flexible belt made of a material such as copper that converts radiation energy, first and second stimulable phosphor layers formed on one surface of this belt and the ground surface, respectively; a belt feeding means for transporting the belt in the longitudinal direction while being stretched at a predetermined position while being able to freely return to the stretched position; an image recording unit that accumulates and records radiation image information on these stimulable phosphor layers by irradiating radiation having information; and a first stimulable phosphor layer after the radiation image information has been accumulated and recorded. a first image reading section which obtains an image signal by irradiating excitation light from an excitation light irradiation means and reading stimulated luminescence light emitted from the contact layer by the excitation light irradiation with a photoelectric reading means; a second image reading section that reads radiation image information from the second stimulable phosphor layer to obtain an image signal; and a first stimulable fluorescent light after the image reading is performed in the first image reading section. a first erasing section that releases radiation energy remaining in the stimulable phosphor layer prior to image recording in the body layer; a second erasing section that emits radiation energy, and subtracting each image signal obtained in the first and second image reading sections between the signals of corresponding pixels to obtain the image information. and a subtraction calculation unit that obtains an image signal for extracting a specific structure inside.

(Example) Hereinafter, the present invention will be described in detail based on an example shown in the drawings.

FIG. 1 shows a radiation image information recording/reading apparatus according to a first embodiment of the present invention. As an example, the apparatus of this embodiment includes a main body 20 and a radiation source storage section 30. As shown in the figure, a first winding shaft 22 and a second winding shaft 23 are arranged in parallel with each other with an interval between them within a casing 29 of the main body 20. These winding shafts 22.
23 are motors 2, which together with the shafts 22, 23 and rollers 27, 28 (to be described later) constitute belt feeding means.
4.25, they are rotated in the directions of arrows A and B, respectively. One end side of a strip-shaped flexible belt 26 made of a thin copper plate is wound around the first winding shaft 22 . This belt 26 is formed in the shape of a long belt with ends,
The other end is held by the second winding shaft 23, and is wound onto the second winding shaft 23 from this other end side. Moreover, this belt 26 is stretched between rollers 27.28 between both winding shafts 22.23.

The upper surface and the lower surface in the figure of the flexible belt 26 are respectively provided with a first stimulable phosphor layer 28A and a second stimulable phosphor layer capable of storing and recording radiation image information as described above. Layer 26B is formed.

A photographing stand 32 is provided at a position facing the belt 26 stretched between the rollers 27 and 28.

The radiation source storage section 30 described above stores therein a radiation source 33 such as an X-ray tube, and this radiation source 33 faces the imaging table 32 . When radiographically photographing a subject (subject) 34, the subject 34 is placed, for example, on his back on the imaging table 32, and the radiation source 33 is activated in this state. As a result, the radiation 35 that has passed through the subject 34 is irradiated onto the stretched belt 26, and the radiation image information of the subject 34 is transferred to the first stimulable phosphor layer 26A carried by the belt 26. is accumulated and recorded.

Further, the radiation 35 transmitted through the first stimulable phosphor layer 26A and the belt 26 is irradiated to the second stimulable phosphor layer 26B on the back side of the belt 26, so that the radiation 35 is transmitted to the stimulable phosphor layer 211iB. Radiographic image information of the subject 34 is also accumulated and recorded. In this case, both stimulable phosphor layers 26A and 26B
Since the belt 26, which has the function of converting radiation energy as described above, is located between them, the first stimulable phosphor layer 28A is exposed to radiation that includes so-called soft wires, thereby reducing the stimulability of the second option. Radiation image information is accumulated and recorded in the phosphor layer 26B by the radiation from which this soft line is removed.

As a result, a specific structure of the subject 34 is recorded in different states on these stimulable phosphor layers 28A and 28B.

As is clear from the above description, in the apparatus of this embodiment, the image recording section 40 is composed of the imaging table 32 and the radiation source 33. Note that in this embodiment, the photographing table 32
A grid 91 for removing scattered radiation is arranged between the flexible belt 2B and the flexible belt 2B.

The radiation image information accumulated and recorded in the first stimulable phosphor layer 2i3A and the second stimulable phosphor layer 28B is converted into an electrical image signal by a first image reading section and a second image reading section, respectively. be read. The first image reading unit includes a laser light source 51, a light deflector 53 such as a polygon mirror that reflects and deflects a laser light 52 as excitation light emitted from the laser light source 51, and a light deflector 53 that reflects the deflected laser light 52. First stimulable phosphor layer 2B on the upper surface side of the flexible belt 2B
A long mirror 59A that scans one-dimensionally on A
, 59B and 59C, are arranged between the mirror 59A and the optical deflector 53, and direct the laser beam 52 to the first stimulable phosphor layer 2.
A scanning lens 58 for focusing on a small spot of a predetermined diameter at every scanning position on the 11iA, and a flexible belt 2
A motor 25 or 24 as a sub-scanning means that rotates at a constant speed while winding up the stimulable phosphor belt 26 is arranged so that the light-receiving surface extends along the scanning line (main scanning line) on the stimulable phosphor belt 26 by the laser beam 52. In addition, a long photomultiplier 54 as a photoelectric reading means, a long light guide 55 optically coupled to the light receiving surface of the long photomultiplier 54, and a light guide 55. and a long photomultiplier 54, which includes a filter (not shown) that cuts excitation light and transmits emitted light. The subject 3 is applied to the first stimulable phosphor layer 26A as described above.
After the radiation image information No. 4 is accumulated and recorded, the motor 25
By rotating the belt 2G, the belt 2G is transferred to the left in the figure at a constant speed. At this time, the second winding shaft 23 is rotated and the belt 2B is wound around the shaft 23. Further, an appropriate load is applied to the first winding shaft 22 side by a known means, so that the belt 26 is always maintained in a tensioned state. As the belt 26 is transported, the laser light source 51 and the optical deflector 53 are activated, and the laser light 52 scans over the first stimulable phosphor layer 2eA. This stimulable phosphor layer 26
From the part of A that was irradiated with the laser beam 52, the scraps 2
Stimulated luminescence light 56 carrying radiation image information stored and recorded in 6A is emitted. This stimulated luminescence light 5G is guided by a light guide 55 and efficiently detected by a long photomultiplier tube 54. While the main scanning of the laser beam 52 is performed as described above, the belt 26 (that is, the stimulable phosphor layer 26A) is transported as described above and sub-scanning is performed, so that the first stimulable phosphor layer 2[iA generates the stimulated luminescent light 56 (i.e., radiation image information) two-dimensionally.
is read. The output S1 of the long photomultiplier tube 54 is sent to a reading circuit 57.

On the other hand, the second image reading section reads the second stimulable phosphor layer 26B.
Read the radiation image information recorded in the. This second
The elements constituting the image reading section are basically the same as those in the first image reading section described above, so in FIG.
(dash) is added and the explanation thereof will be omitted.

Note that the sub-scanning means of the second image reading section is also used as that of the first image reading section.

That is, by rotating the motor 25 or 24 and transporting the belt 26, the second stimulable phosphor layer 26B is sub-scanned by the laser beam 52'. Further, in this second image reading section, a single long mirror 59'' is provided to reflect the deflected laser beam 52' toward the second stimulable phosphor layer 26B. The output Sz of the elongated photomultiplier tube 54° of the second image reading section (that is, the information indicating the radiation image recorded on the second stimulable phosphor layer 28B) is also sent to the reading circuit 57. The elongated photomultiplier tube is described in detail in, for example, Japanese Patent Laid-Open No. 16666/1983.

Next, the processing in the reading circuit 57 will be explained with reference to FIG. 2, which schematically shows its configuration. Long photomultiplier tube 5
4 is logarithmically amplified by a logarithmic amplifier 8o, and then digitized by an A/D converter 81. The digital read image signal logs1 obtained in this way is temporarily stored in the frame memory 82, and then read out from there and input to the subtraction calculation circuit 83.

Similarly, the output S2 of the long photomultiplier tube 54' is logarithmically amplified by a logarithmic amplifier 84 and then digitized by an A/D converter 85. The digital read image signal +ogs2 thus obtained is also temporarily stored in the frame memory 82, and then read out from there and input to the subtraction calculation circuit 83.

The subtraction calculation circuit 83 subjects the two input image signals 10g5l and IogSz to appropriate weighting and subtracts them for each corresponding pixel to generate a digital difference signal 5sub -a φlogs1-b ・IogSz -
c [a-b is a weighting coefficient, C is a bias component]. After this difference signal Ssub undergoes image processing such as gradation processing and frequency processing in the image processing circuit 87,
It is sent to an image reproducing device 88 outside the recording/reading device and used for reproducing the radiation image. This playback device 88 is a CRT
It may be a display means such as, a recording device that performs optical scanning recording on a photosensitive film, or it may be replaced with a device that temporarily stores the image signal in an image file such as an optical disk or a magnetic disk. .

When performing the above-mentioned subtraction operation, the coefficient a
When Sb is appropriately determined, signal components for portions other than the specific structure are eliminated in the obtained difference signal Ssub. Therefore, this difference signal S s
By performing image reproduction based on ub, it is possible to obtain a radiation image in which only the above-mentioned specific structure is extracted. When performing this subtraction operation, it is necessary to perform subtraction between corresponding pixels as described above. To do this, for example, as shown in FIG. 1, a marker 92 is placed near the subject 34, and both image signals logS1
, +ogs2, positioning may be performed using the signal indicating this marker 92 as a reference signal. However, since the relative positional relationship between the phosphor layers 26A and 26B is fixed, if the readout position is always fixed, it is not necessarily necessary to use a marker to make the pixels correspond.

Note that it is also possible to reproduce a normal radiographic image based on these signals 10g5l or +ogsz without specifically sending the read image signals 1o, gSl, or logsz to the subtraction calculation circuit 83, and for that purpose, these image signals 1ogs1 , logS2 may be recorded and accumulated in an image file such as an optical disk.

The portion of the belt 26 carrying the first and second stimulable phosphor layers 28A and 26B whose images have been read as described above is wound around the second winding shaft 23 and stored there. . At the same time, another part of the belt 26 that had been wound around the first winding shaft 22 is stretched between the rollers 27 and 28, so that the stimulable phosphor layer 26A and the stimulable phosphor layer 26A carried on this part Radiographic image information can be recorded on 26B in the same manner as described above. In this way, radiographic image information is recorded over almost the entire length of the belt 26, and all of the belt 26 that has been wound and stored around the first winding shaft 22 is sent out to the second winding shaft 23. , the motor 24 is driven, and the first winding shaft 22 moves in the direction of arrow A.
rotated in the direction As a result, the belt 26 that had been wound around the second winding shaft 23 is all returned to the first winding shaft 22 side, but at this time, the belt 26 that was wound around the second winding shaft 23 is returned to the first winding shaft 22 side.
The belt 26 passes through the erasing section 60 and the second erasing section 60'', and the first and second stimulable phosphor layers 26A and 26B carried on the belt undergo image (afterimage) erasure. As an example, the erasing section 60, 60' is composed of erasing light sources 61, 81' arranged above and below the stretched belt 26. These erasing light sources 61, 61' are, for example, fluorescent lamps. It mainly emits light in the excitation wavelength range of the stimulable phosphor, and is turned on when the belt 26 is returned to the first winding shaft 22 side.After reading the image, the first and second The radiation energy remaining in the stimulable phosphor belt layers 26A and 28B is removed by the irradiation with the above-mentioned light, and the radiation energy is removed from the stimulable phosphor belt layers 26A and 28B.
.

Emitted from 26B.

In this way, the belt 26 carrying the stimulable phosphor layers 2GA and 26B, whose images (afterimages) have been erased to the extent that radiation image information can be recorded again, is mounted on the first winding shaft 22.
Since the images are stored, it becomes possible to repeat the above-described image recording (photographing) and reading using this belt 26. As the erasing light source 61, 61', in addition to the above-mentioned fluorescent lamp, for example, a tungsten lamp, a halogen lamp, an infrared lamp, a xenon flash lamp, etc. as shown in JP-A No. 56-11392 can be arbitrarily selected and used. .

Further, the erasing section 60.60'' is configured from the above-mentioned erasing light source, and also includes, for example, an LED (Light Emi).
ttlng D 1ode) may be constructed from a planar light source such as a panel or an EL (electro-luminescence) plate in which light beams (ttlng D 1ode) are two-dimensionally arranged.

In the above, a case has been described in which the radiation image information is stored and recorded in the stimulable phosphor layers 28A and 26B and then immediately read by the image reading unit.
The present device can also be used so that image reading in the image reading unit is postponed and multiple image recordings (photographs) are performed one after another.

In other words, in this case, the entire portion of the belt 2G carrying the stimulable phosphor layers 26A and 26B on which images have been recorded is wound around the second winding shaft 23, and after a series of image recording is completed, , the belt 26 may be returned from the second winding shaft 23 to the first winding shaft 22 side, and at that time, the image reading section may read the image.

Next, a second embodiment of the present invention will be described with reference to FIG. Note that in FIG. 3, elements equivalent to those in FIG. 1 are given the same numbers, and explanations thereof will be omitted unless particularly necessary. In the apparatus shown in FIG. 3, the belt 126 is an endless belt, which is stretched in an annular manner between a pair of rollers 122 and 123, and the driving roller 123 is rotated by the motor 25, so that the image recording section, The images are sequentially sent to the image reading section and the erasing section. In this example, the laser light source 51°, the optical deflector 53°, etc. that constitute the second image reading section that reads radiation image information from the second stimulable phosphor layer 26B are arranged inside the belt 126. There is.

In this embodiment, a plurality of erasing light sources 61' constituting the second erasing section 60' are arranged inside the belt 126, and the erasing light sources 61' are e.g.
Image-recordable stimulable phosphor layer 2G supported on 6
It is turned on when the part B is fed into the image recording section 40. Erasing light source 6 constituting the erasing unit 60 of solution 1
1 is turned on while the image-recordable stimulable phosphor layer 26A carried by the belt 126 is being conveyed toward the image recording section 40. During this period, image reading is generally performed, so using a suitable light shielding plate or a pair of nip rollers (not shown), the light emitted by the erasing light source 6I is irradiated onto the stimulable phosphor layers 26A and 26B before image reading. to avoid being

(Effects of the Invention) As described above in detail, in the radiation image information recording/reading device of the present invention, the first
By forming the second stimulable phosphor layer, radiation image information for subtraction can be simultaneously recorded (photographed) on these layers, and an image reading section is provided for each stimulable phosphor layer. With this structure, the radiographic image information stored in each layer can be read in parallel.
With this device, it is possible to perform subtraction quickly, and the efficiency of diagnostic work, especially in group medical examinations, etc., can be significantly improved.

[Brief explanation of the drawing]

FIG. 1 is a schematic side view showing a first embodiment of the present invention; FIG. 2 is a block diagram showing the configuration of a radiation image information reading circuit of the above embodiment; FIG. 3 is a second embodiment of the present invention. FIG. 2 is a schematic side view showing the device. 20... Main body 22... First winder 23... Second winder 241.25...
Motor 2G, 126... Flexible belt 26A... First stimulable phosphor layer 26B... Second stimulable phosphor layer 27... Roller 28... Drive roller 30... Radiation source storage section 32...imaging table 3
3... Radiation source 34... Subject 35.
...Radiation 40...Image recording section 51.
51°...Laser light source 52.52'...Laser light 53.53''...Light deflector 54.54°...
・Photomultiplier tube 56.56″...stimulated luminescent light 57
...reading circuit 60.60' ...erasing section 6
1.61'... Erasing light source 80.84... Logarithmic amplifier 81. , 85... A/D converter 82.86.
...Frame memory 83...Subtraction calculation circuit 122...Roller 123...Drive roller 10g5l, IogS2...Read image signal S
sub...difference signal

Claims (4)

[Claims] (1) A band-shaped flexible belt made of a material that converts radiation energy, and first and second stimulable phosphors that are formed on one surface and the other surface of this belt to store and record radiation image information, respectively. a belt feeding means for transporting the belt in the longitudinal direction while the belt is stretched in a predetermined position while being able to return to the stretched position; and first and second accumulation properties in the stretched portion of the belt. an image recording section that accumulates and records radiation image information in the stimulable phosphor layer by irradiating the phosphor layer with radiation having image information; a first image reading unit that irradiates the stimulable phosphor layer with excitation light from the excitation light irradiation means and reads stimulated luminescence light emitted from the layer by the irradiation of the excitation light with the photoelectric reading means to obtain an image signal; and irradiating excitation light from an excitation light irradiation means to the second stimulable phosphor layer after the radiation image information has been accumulated and recorded, and irradiating stimulated luminescence light emitted from the layer by this excitation light irradiation. a second image reading unit that reads an image signal using a photoelectric reading unit; and an image is recorded on the first stimulable phosphor layer after the image is read in the first image reading unit; First, a first erasing unit releases radiation energy remaining in the stimulable phosphor layer, and a second stimulable phosphor layer after the image is read in the second image reading unit. Prior to image recording, a second erasing unit releases radiation energy remaining in the stimulable phosphor layer, and each image signal obtained in the first and second image reading units is , a subtraction calculation unit that obtains an image signal by subtracting between signals for corresponding pixels to extract a specific structure in the image information. (2) The flexible belt is formed into a belt shape with ends, and the belt feeding means for transporting the belt includes two winding shafts that wind one end and the other end of the belt, respectively. A radiation image information recording/reading device according to claim 1, characterized in that: (3) A patent claim characterized in that the flexible belt is formed in the shape of an endless belt, and the belt feeding means for transporting the belt includes a plurality of rollers that stretch the belt in an annular shape. The radiation image information recording/reading device according to item 1. (4) The radiation image information recording/reading device according to any one of claims 1 to 3, wherein the flexible belt is made of a thin copper plate.