JP2561297B2 - Radiation image information reader - Google Patents

Description

TECHNICAL FIELD The present invention relates to a radiation image reading apparatus used in a radiation image information recording / reproducing system.

<Prior art and its problems> As a method of obtaining a radiographic image as an image, a so-called radiographic system using a combination of a radiographic film having an emulsion layer made of a silver salt photosensitive material and an intensifying screen has been conventionally used. ing. Recently, a radiographic image conversion system using a stimulable phosphor has attracted attention as an alternative to the radiographic system.

Here, the stimulable phosphor means radiation (X-ray, α-ray, β-ray).
Ray, γ ray, electron beam, ultraviolet ray, etc.), some of the energy of this radiation is accumulated in the phosphor, and then excitation light such as visible light is irradiated, depending on the accumulated energy. It means a phosphor showing stimulated emission.

Using this stimulable phosphor, the radiation image information of a subject such as a human body is temporarily stored in a sheet having a layer of the stimulable phosphor (hereinafter referred to as "stimulable phosphor sheet" or simply "phosphor sheet"). After recording, this sheet is scanned with excitation light to cause stimulated emission, the generated stimulated emission light is read by a photoelectric conversion element and converted into an electric signal to obtain an image signal, and this image signal is processed to make a diagnosis appropriate. A radiation image information recording / reproducing system for obtaining a good radiation image of a subject has been proposed (for example, JP-A Nos. 55-12429, 56-11395, and 55-55).
163472, 56-104645, 55-116340, etc.).

In addition, according to this system, the radiation image information stored in the stimulable phosphor is converted into an electric signal and then subjected to appropriate signal processing, and the electric signal is used to display a recording material such as a photographic light-sensitive material or a CRT. The radiation image is output to the apparatus as a visible image, whereby a radiation image excellent in observation and interpretation suitability (diagnosis suitability) can be obtained.

By the way, in the radiation image information recording / reproducing system, a stimulable phosphor sheet on which radiation image information of a subject is stored and recorded is scanned by excitation light, and the stimulated emission light emitted from the phosphor sheet by this scanning is emitted. Prior to the reading of radiation image information (hereinafter referred to as "main reading"), which is read by the photoelectric reading means to obtain an electric image signal for reproducing a visible image for observation and interpretation, the excitation light used for this main reading is used in advance. "Pre-reading" that scans the phosphor sheet with low-level excitation light to read the outline of the radiation image information stored and recorded in this phosphor sheet
A system is known in which the reading conditions and the like for performing the main reading are determined based on the image information obtained by the pre-reading, and the main reading is performed according to the reading conditions. It is described in JP-A-58-67243, JP-A-58-67244 and JP-A-61-84958, which have been previously filed and published.

In the radiation image information reading device disclosed in the above-mentioned publication, in pre-reading, the beam diameter of the excitation light beam for scanning the stimulable phosphor sheet is expanded, and the light amount is reduced.
In addition, by operating the excitation light beam adjusting means for changing the optical path, the main reading optical system and the pre-reading optical system are shared. An example thereof is shown in FIG. In the radiation image information reading device 60 shown in FIG. 5, pre-reading is first performed on the stimulable phosphor sheet 20 on which radiation image information is stored and recorded.

The excitation light beam 22 emitted from the excitation light source 12 has its beam diameter adjusted by the beam expander 24, and enters the excitation light beam adjusting means 16. As shown in FIG. 6, the excitation light beam 22 is prevented from being enlarged in beam diameter by the concave lens 26 in the excitation light beam adjusting means 16 and part of the enlarged pre-reading light beam 30 being blocked by the light guide 44. Therefore, the optical path is changed in the direction away from the incident end surface of the light guide 44 (upward in FIG. 6).
This reduces the light amount.

Next, the pre-reading light beam 30 is one-dimensionally deflected by an optical deflector 32 such as a galvanometer mirror, and is lowered by a plane reflecting mirror 38 so that the stimulable phosphor sheet 20.
Scan the top one-dimensionally. Here, as shown in FIG. 7, the excitation light beam adjusting means 16 is actuated to interlock with the pre-reading light beam 30 so that the pre-reading light beam 30 is not blocked. The reflection mirror 48 has been moved.

Further, an fθ lens 36 is arranged between the light deflector and the plane reflection mirror 38 so that the one-dimensionally deflected light beam 30 scans the surface of the phosphor sheet 20 at a constant speed. ing. At this time, the stimulable phosphor sheet 20 is simultaneously indicated by the arrow A.
The sub-scanning conveyance mechanism 42 carries the sub-scanning in the direction indicated by. As a result, the pre-reading light beam 30 is applied to the entire surface of the phosphor sheet 20.

In this way, when the light beam 30 is irradiated, stimulated emission light of a light amount corresponding to the radiation energy accumulated and recorded in the stimulable phosphor sheet 20 is generated. This stimulated emission light is incident on the light guide 44. The light guide 44 has a linear entrance surface, is arranged adjacent to the main scanning line 40 defined on the stimulable phosphor sheet 20 so as to face the main scanning line 40, and has an annular exit end. Photodetector such as photomultiplier 46
Is connected to the light-receiving surface of the photodetector 46 and is configured so that the photostimulated luminescence light incident from the incident surface can be transmitted to the light-receiving surface of the photodetector 46 attached to the emission end.

A filter (not shown) is attached to the light receiving surface of the photodetector 46. This filter cuts the excitation light that has entered through the light guide 44 due to reflection or the like, and allows only the stimulated emission light to pass through.
Receives only the stimulated emission light and photoelectrically converts the radiation image information stored in the stimulable phosphor sheet 20 into an electric signal.

The electric signal detected by the photodetector 46 is amplified by the pre-reading amplifier 54, transmitted to the control circuit 56, and the amplification factor setting value a, which is the reading condition at the time of the main reading, according to the obtained radiation image information, The recording scale factor setting value b, the image processing condition setting value c, etc. are determined. In this way, prefetching is completed.

Next, the stimulable phosphor sheet 20 is reversely conveyed by the sub-scanning conveyance mechanism, returned to the main reading start position, and main reading is started. In this reading, excitation light beam adjusting means
16 does not act, and the condensing reflection mirror 48 linked to the excitation light beam adjusting means 16 is moved to the stimulated emission light reflection position shown by the solid line in FIGS. 5 and 7.

That is, the excitation light beam 22 emitted from the excitation light source 12
After the beam diameter is strictly adjusted by the beam expander 24, the light directly enters the optical deflector 32 and is one-dimensionally deflected. This one-dimensionally polarized excitation light beam 22 is f
After being adjusted by the θ lens 36 so that it is always at a constant speed regardless of the position on the surface of the stimulable phosphor sheet 20, it is lowered by the reflecting mirror 38 to one-dimensionally move on the phosphor sheet 20. Scan. Also at this time, the phosphor sheet 20 is simultaneously sub-scanned and conveyed by the sub-scanning and conveying mechanism 42 in the direction indicated by the arrow A, and as a result, the excitation light beam 22 is applied to the entire surface of the phosphor sheet 20.

Storage phosphor sheet 20 irradiated with excitation light beam 22
Emits stimulated emission according to the energy level of the stored and recorded radiation image information, and this stimulated emission light enters the light guide 44 as in the case of the pre-reading. Since stimulated emission is omnidirectional and is weak light, it is for condensing light having the same length as the incident end face of the light guide 44 on the opposite side of the incident end face with respect to the main scanning line. A reflection mirror 48 is arranged so as to face the incident end face, and the reflection mirror 48 enhances the efficiency of collecting the stimulated emission light. In order to improve the light collection efficiency, the clearance between the light guide 44 and the light collection reflection mirror 48 should be as narrow as possible if the excitation light beam 22 can pass through. As described above, the condensing reflection mirror 48 is separated from the optical path so as not to block the large-diameter pre-reading light beam during pre-reading, and can be moved so that it only works during main reading. Is configured.

In this way, the stimulated emission light is efficiently guided by the light.
It is made incident on 44 and transmitted inside it, and photodetector 46
The light is received by and photoelectrically converted into an electric signal. The electric signal is amplified to an electric signal of an appropriate level by the main reading amplifier 62 whose sensitivity is set based on the amplification factor setting value a determined in the pre-reading. The amplified electrical signal is
It is input to the A / D converter 64 and is converted into a digital signal with a scale factor suitable for the signal fluctuation width based on the recording scale factor setting value b determined in the pre-reading.
This digital signal is input to the signal processing circuit 66, signal processing is performed based on the reproduction image processing condition set value c determined in the pre-reading so as to obtain a radiation image excellent in observation and interpretation, and the radiation image is visualized. The image is transmitted to a reproducing device which outputs the image.

By the way, as shown in FIG. 6, when the concave lens 26 is used as the excitation light beam adjusting means 16 which is conventionally operated at the time of pre-reading, the concave lens 26 is applied to the excitation light beam 22 from the center of the lens. By inserting it so as to be eccentric, the beam diameter is expanded and the read main scanning line position is moved. However, if the excitation light beam is displaced due to beam wandering or the like, the pre-reading light beam cannot define the main scanning line at a predetermined position at the reading position, and the light guide or converging reflection mirror partially causes the main scanning line. Is blocked, a part of the light beam deviates from the deflection surface of the optical deflector, and the incident position of the light beam on the concave lens fluctuates, so that a predetermined beam diameter cannot be obtained. there were.

Therefore, even if the excitation light beam is displaced due to beam wandering or the like, the mirror area of the galvanometer mirror can be increased so that the light beam can be used, or the light guide and focusing reflection at the reading position can be performed. There was a problem such as having to deal with it by increasing the clearance with the mirror.

<Object of the Invention> An object of the present invention is to solve the above-mentioned problems of the prior art, and to adjust the amount of adjustment of the excitation light beam adjusting means that acts on the optical path of the excitation light beam of the reading device for pre-reading. Is adjusted according to the excitation light beam information at the scanning position of the stimulable phosphor sheet on which the radiation image information is stored and recorded, whereby a pre-reading scanning position shift caused by beam wandering or the like can be avoided. It is to provide an information reading device.

<Brief Description of the Invention> In order to achieve the above object, the present invention provides an excitation light source that emits an excitation light beam that scans a stimulable phosphor sheet that stores and records radiation image information, and a scan by the excitation light beam. A photoelectric reading unit that photoelectrically reads stimulated emission light emitted from the stimulable phosphor sheet, and acts on the excitation light beam to expand the beam diameter on the surface of the stimulable phosphor sheet and to Changing the optical path, having an excitation light beam adjusting means capable of advancing and retreating to and from the optical path of the excitation light beam, prior to the main reading for reading the radiation image information stored and recorded in the stimulable phosphor sheet, The pre-reading is performed by causing the excitation light beam adjusting means to act on the excitation light beam optical path to read the outline of the radiation image information accumulated and recorded in the stimulable phosphor sheet. In the radiation image information reading apparatus, the excitation light beam adjusting means is positionally adjustable on the excitation light beam route, and the excitation light beam detecting means detects the excitation light beam at the scanning position of the stimulable phosphor sheet. And, in the pre-reading, so that the excitation light beam for pre-reading is incident on a predetermined position of the stimulable phosphor sheet, according to the excitation light beam information detected by the excitation light beam detection means In addition, the radiation image information reading device is configured to adjust the position of the excitation light beam adjusting means.

<Specific Configuration of the Invention> The radiation image information reading apparatus according to the present invention will be described below in detail with reference to the preferred embodiments shown in the accompanying drawings.

FIG. 1 is a perspective view conceptually showing a radiation image information reading apparatus 10 according to the present invention.

As shown in FIGS. 1 and 2, the radiation image information reading device 10 has an excitation light source 12, a photoelectric reading means 14, an excitation light beam adjusting means 16, and an excitation light beam detecting means 18.

The radiation image information reading device 10 shown in FIG. 1 has the same configuration as the radiation image reading device shown in FIG. 5 except for the light beam detecting means 18 and the like, that is, only the configuration in the pre-reading differs. Since the configuration in this reading is the same, the same components are denoted by the same reference numerals, detailed description and action thereof will be simplified, and the characteristic part of the radiation image information reading device 10 of the present invention will be described below.

Although the radiation image information reading apparatus 10 shown in FIG. 1 is adjusted for pre-reading, it is emitted from an excitation light source 12 that emits an excitation light beam that scans a stimulable phosphor sheet 20 on which radiation image information is stored and recorded. The excitation light beam 22 is configured such that the beam diameter thereof is strictly adjusted by the adjacent beam expander 24 and is incident on the excitation beam adjusting means 16.

As shown in FIG. 2, the exciting light beam adjusting means 16 acts on the exciting light beam 22 to increase the beam diameter on the surface of the phosphor sheet 20, and the acting light beam 22 to act on the light beam 22. A concave lens 26 that also serves as an optical path changing unit that changes the optical path of 22 and a light amount reducing unit that acts on the light beam 22 to reduce the light amount of the light beam 22.
The ND filter 28 is used to direct the light beam 22 as a pre-read light beam 30 to the light deflector 32. Further, the light beam adjusting means 16 has a driving means 34, and the driving means 34 is composed of a driving device 34a such as a motor and a drive control system 34b, and the pre-reading light beam from the excitation light beam detecting means 18 at the time of pre-reading.
The movement amount can be finely adjusted based on the information (position, beam diameter, etc.) of 30 and the light beam 22 can be largely moved so as not to affect the light beam 22 during the main reading.

The optical deflector 32 drives a galvanometer mirror, a rotary polygon mirror, or the like to drive the pre-read light beam 30 or the light beam 22.
(At the time of actual reading) is deflected in a one-dimensional direction by a predetermined angle, and the deflected light beam 30 or 22 passes through the fθ lens 36 and is lowered by the plane reflection mirror 38, and the stimulable phosphor sheet 20. The main scanning is performed one-dimensionally on the surface to define the pre-reading main scanning line 40 or the main reading main scanning line 41, respectively. The fθ lens 36 is configured so that the one-dimensionally polarized excitation light beam 22 or pre-reading light beam 30 is always at a constant velocity in the main scanning direction, regardless of the position on the surface of the phosphor sheet 20. There is. By the way, the plane reflection mirror 38 is usually composed of a half mirror, a synchronization signal generator (not shown) is arranged behind the plane reflection mirror 38, and the plane reflection mirror 38 is arranged on the grid of the synchronization signal generator.
The scanning position of the light beam 22 is detected by injecting the light beam that has passed through.

On the other hand, the phosphor sheet 20 is at the same time as the one-dimensional main scanning,
It is configured to be sub-scanned and transported by the sub-scanning transport mechanism 42 in the direction indicated by arrow A, and as a result, the entire surface of the phosphor sheet 20 is irradiated with the light beam 22 or 30.

When the light beam 22 or 30 is irradiated in this manner, stimulated emission light of a light amount corresponding to the radiation energy accumulated and recorded in the stimulable phosphor sheet 20 is generated. Read photoelectrically by 14. The photoelectric reading unit 14 includes a light guide 44 having a linear incident end and an annular emitting end that are adjacent to each other facing the main scanning line 40 or 41, and a photomultiplier attached to the emitting end. The photodetector 46 is constituted, and the stimulated emission light incident on the light guide 44 is transmitted to the emission end, and the excitation light incident on the light guide 44 together with the stimulated emission light is cut off by the filter. The radiation image information incident on the light receiving surface and accumulated and recorded in the stimulable phosphor sheet 20 is photoelectrically converted into an electric signal.

Here, as shown in FIG. 2 and FIG. 3, during the pre-reading, the excitation light beam adjusting means 16 is operated to increase the beam diameter of the pre-reading light beam 30, but at that time, the light beam 30 The light beam 30 is moved from the scanning position 41a in the main reading to the scanning position 40a in the pre-reading so that the light beam 30 is not blocked by the end surface of the light guide 44. Therefore, the condensing reflection mirror 48 provided for improving the condensing efficiency of the stimulated emission light during the main reading is also configured to be moved so as not to block the pre-reading light beam 30. Incidentally, the excitation light beam detection means 18 for detecting the position and the beam diameter of the pre-reading light beam 30 is provided in correspondence with the correct scanning position 40a of the pre-reading light beam 30. The excitation light beam detecting means 18 is a beam sensor 50 having a light receiving element which is arranged on the scanning line of the pre-read light beam 30 and receives the light beam 30.
And a processing device 52 for processing the light beam information detected by the beam sensor 50. As the light receiving element, a known position sensor such as a two-dimensional array of photoelectric conversion elements such as photodiodes and phototransistors can be used. The light beam information (position and beam diameter) of the pre-read light beam 30 detected by the beam sensor 50 of the light beam detection means 18 is transmitted to the drive control system 34b so that the processing device 52 can obtain a necessary movement amount, By driving the driving device 34a, the excitation light beam adjusting means 16 is constantly adjusted so as to obtain a desired light beam position and beam diameter.

The electric signal of the radiation image information detected by the photodetector 46 as the pre-reading is amplified by the pre-reading amplifier 54, transmitted to the control circuit 56, and the amplification which is the reading condition at the time of the main reading according to the obtained radiation image information. The rate setting value a, the recording scale factor setting value b, the image processing condition setting value c, etc. are determined.

In this way, the pre-reading ends and the main reading is performed next. Since the radiation image reading apparatus 10 shown in FIG. 1 and the radiation image reading apparatus 60 shown in FIG. 5 have the same configuration in the main reading, each of the main readings Since the details and operation of the constituent elements have been described above, the description thereof will be omitted.

In the example shown in FIG. 2, the light beam diameter expanding means and the optical path changing means are constituted by one concave lens 26, and the light amount reducing means is constituted by the ND filter 28 to form the excitation light beam adjusting means 16. Is not limited to this,
The excitation light beam adjusting means 16 may be composed of the light beam diameter expanding means, the optical path changing means, and the light quantity reducing means.

As the light beam diameter expanding means, any means can be used as long as it can expand the beam diameter on the surface of the phosphor sheet 20 to a desired diameter, for example, about 3 mm, and a convex lens may be used.

The optical path changing means may be any as long as the enlarged pre-reading light beam 30 can be moved to a position not blocked by the light guide 44, or the condensing reflection mirror 48 moved to a position where it does not act, and a convex lens is used. It may be eccentrically used, a prism may be used, or a tilted transparent plane-parallel plate 58 like the excitation light adjusting means 16 'shown in FIG. 4 may be used. In the excitation light adjusting means 16 'shown in FIG. 4, the concave lens 26 allows the excitation light beam 22 to enter the center of the optical axis without decentering the optical axis with respect to the light beam, and only enlarges the beam diameter. The action of
The parallel plane plate 58 is tilted with respect to the light beam 22 to change the optical path, and the ND filter 28 is used to reduce the amount of light. Therefore, the excitation light beam adjusting means shown in FIG.
As in the case of 16, the beam diameter is enlarged and the optical path is changed without causing aberration as in the case where the light beam 22 is made incident on a portion of the concave lens 26 which is deviated from the optical axis center. It is not necessary to set the action (incident) position strictly.

As the light quantity reducing means, any means can be used as long as it can reduce the light quantity of the excitation light beam 22 adjusted for the main reading to the energy level for prereading with the increase of the beam diameter, but the ND filter is preferable. Of course, the parallel plane plate used as the above-mentioned optical path changing means may be processed and used as a filter.

In the example shown in FIGS. 2 and 4, the excitation light beam adjusting means 16 and 16 'having the above-mentioned light beam diameter enlarging means, optical path changing means and light quantity reducing means are integrally combined with each other, and the driving means 34 is used. However, the present invention is not limited to this, and each of the above-mentioned means may be separately arranged and each of the means may be separately adjusted for movement. .

In the example shown in FIGS. 1 and 3, the excitation light beam detection means 18 is composed of the beam sensor 50 and the processing device 52, and the information (position and beam diameter) of the pre-read light beam 30 is detected as an electric signal, Although it is configured to finely adjust the excitation light beam adjusting means 16 by transmitting it to the driving means 34, the information detected by the excitation light beam detecting means 18 can be visually displayed and manually finely adjusted. Good.

The radiation image reading apparatus according to the present invention is basically configured as described above, but the present invention is not limited to this, and is improved and designed within the scope not departing from the gist of the present invention. Of course, it is possible to change.

<Effects of the Invention> As described above in detail, according to the present invention, the excitation light beam information is detected at the reading position during the pre-reading, and the adjustment amount of the excitation light beam adjusting means is adjusted according to the information. With this configuration, the diameter of the light beam can be expanded and the optical path can be changed with high accuracy.

Therefore, according to the present invention, even if beam wandering occurs in the excitation light beam during pre-reading, fine adjustment can be performed by the excitation light beam adjusting means, so that the correct beam position is always maintained.
Radiation that can maintain the beam diameter, does not need to increase the rotating mirror of the optical deflector or the mirror area of the rotating mirror, and can narrow the clearance between the light guide and the condensing reflection mirror. An image information reading device can be provided.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a radiation image information reading apparatus according to the present invention. FIG. 2 is a schematic sectional view showing an embodiment of the excitation light beam adjusting means in FIG. FIG. 3 is a side view showing details of the reading portion in FIG. FIG. 4 is a schematic sectional view showing another embodiment of the pumping light beam adjusting means in FIG. FIG. 5 is a perspective view of a conventional radiation image reading apparatus. FIG. 6 is a schematic sectional view of the excitation light beam adjusting means in FIG. FIG. 7 is a side view showing details of the reading portion in FIG. Explanation of symbols 10, 60 ... Radiation image information reader, 12 ... Excitation light source, 14 ... Photoelectric reading means, 16, 16 '... Excitation light beam adjusting means, 18 ... Excitation light beam detecting means, 20 ... … Storing phosphor sheet, 22 …… Excitation light beam, 24 …… Beam expander, 26 …… Concave lens, 28 …… ND filter, 30 …… Look ahead light beam, 32 …… Optical deflector, 34 …… Drive means, 36 ... f.theta. Lens, 38 ... Planar reflection mirror, 40 ... Pre-read main scan line, 41 ... Main read main scan line, 42 ... Sub-scan transport mechanism, 44 ... Optical guide, 46 ... Photodetector, 48 ... Reflecting mirror for condensing, 50 ... Beam sensor, 52 ... Processor, 54 ... Preamplifier, 56 ... Control circuit, 58 ... Parallel plane plate, 62 ... For this reading Amplifier, 64 …… AD converter, 66 …… Signal processing circuit, A …… Transfer direction of stimulable phosphor sheet

Claims (1)

(57) [Claims] 1. An excitation light source that emits an excitation light beam for scanning a stimulable phosphor sheet that stores and records radiation image information.
A photoelectric reading unit that photoelectrically reads stimulated emission light emitted from the stimulable phosphor sheet by scanning with the excitation light beam, and a beam diameter on the surface of the stimulable phosphor sheet that acts on the excitation light beam. A radiation image accumulated and recorded on the stimulable phosphor sheet, which has an excitation light beam adjusting means that expands and changes the optical path of the light beam and that can advance and retreat to and from the optical path of the excitation light beam. Prior to the main reading for reading information, a radiation image information reading device for performing a pre-read for reading the outline of the radiation image information accumulated and recorded in the stimulable phosphor sheet by causing the excitation light beam adjusting means to act on the excitation light beam optical path In, while enabling position adjustment of the excitation light beam adjusting means on the excitation light beam optical path, at the scanning position of the stimulable phosphor sheet And an excitation light beam detecting means for detecting the excitation light beam, wherein during the pre-reading, the excitation light beam for pre-reading is incident on a predetermined position of the stimulable phosphor sheet, the excitation light beam A radiation image information reading device, characterized in that the position of the excitation light beam adjusting means is adjusted according to the excitation light beam information detected by the detecting means.