JP2003280119A - Image information reader - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To carry out with a simple configuration a highly accurate and efficient reading process in which vibration unevenness is hardly recognized visually. <P>SOLUTION: The material of a support which constitutes a stimulable phosphor sheet IP, the thickness of the support and a condition for fixing the stimulable phosphor sheet IP are set so that the natural frequency fn1 (Hz) of the stimulable phosphor sheet IP and the moving speed Vr (mm/s) of a scanner head 42 in a subdirection satisfy the relationship of fn1/Vr≥0.8 or fn1/Vr≤0.2. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention irradiates a stimulable phosphor sheet in which radiation image information of a subject is stored and recorded with excitation light in a main direction, and irradiates the stimulable light from the stimulable phosphor sheet. The present invention relates to an image information reading device that relatively conveys a reading unit that reads emitted stimulated emission light and the stimulable phosphor sheet in a sub-direction that is substantially orthogonal to the main direction.

[0002]

2. Description of the Related Art Conventionally, radiation (X-ray, α-ray, β-ray,
When gamma rays, electron beams, ultraviolet rays, etc.) are irradiated, a part of this radiation energy is accumulated, and when irradiation with excitation light such as visible light is then irradiated, stimulated emission is shown depending on the accumulated energy intensity. There is known a system that utilizes a phosphor (stimulable phosphor) to reproduce radiation image information of a subject such as a human body on a photographic light-sensitive material or to output it as a visible image on a CRT or the like.

Specifically, radiation image information of a subject such as a human body is once recorded on a stimulable phosphor sheet having a sheet-shaped stimulable phosphor layer, and the stimulable phosphor sheet is excited by a laser beam or the like. After generating stimulated emission light by irradiating the light, a recording medium such as a photographic light-sensitive material or a CRT is generated based on an image signal obtained by photoelectrically reading the stimulated emission light.
Various devices that output (reproduce) a radiation image of a subject as a visible image on a display device such as the above are adopted.

By the way, in the above-mentioned device, the vibration unevenness is visually recognized due to the vibration from the outside, the vibration from the driving portion in the device, etc., and the radiation image information carried on the stimulable phosphor sheet is highly accurately detected. It may not be readable. Therefore, for example, Japanese Patent Laid-Open No. 10-18655
As disclosed in Japanese Patent Publication No. 3, a photostimulable phosphor panel for recording radiation image information is provided, and when the photostimulable phosphor panel is integrated with the photostimulable phosphor panel, There is known a radiation image reading apparatus in which a vibration-proof plate having a higher natural frequency than that of the case is integrally provided with the stimulable phosphor panel.

Specifically, as shown in FIG. 6, this device has a vibration-proof plate 2 fixed to an inner casing 1, and the vibration-proof plate 2 is provided with a mounting member 3 to irradiate it. Fluorescent phosphor panel 4 is integrally attached. The anti-vibration plate 2 is configured by sandwiching a foamed acrylic 6 between a pair of carbon plates 5.

As described above, according to the conventional technique, the natural frequency when the vibration damping plate 2 in which the foamed acrylic 6 is sandwiched between the pair of carbon plates 5 is integrated with the panel 4 is the natural frequency of the panel 4 alone. By setting the number higher than the number, the vibration is absorbed, and when viewed by human eyes, the radiation image becomes less noticeable.

[0007]

However, in the above-mentioned prior art, since the panel 4 and the vibration-proof plate 2 are formed by different members, the panel 4 and the vibration-proof plate 2 cannot be replaced when the panel 4 is replaced. It is difficult to maintain a highly accurate mounting state on the vibration plate 2.

Further, when a light-collecting system using a CCD (charge coupled device) is used in order to downsize the device and speed up the reading process, the distance variation between the light-collecting system and the panel 4 is , It is necessary to keep the thickness within the plane, for example, 100 μm or less. However, when attaching and detaching the panel 4 to and from the vibration-proof plate 2 as described above, it is difficult to maintain the flatness of the panel 4 within a desired accuracy range (for example, within 100 μm). It has been pointed out.

The present invention solves this kind of problem, and effectively prevents visible unevenness of vibration with a simple structure, and replaces the stimulable phosphor sheet easily and highly accurately. An object is to provide a possible image information reading device.

[0010]

In the image information reading apparatus according to the present invention, the stimulable phosphor sheet in which the radiation image information of the subject is stored and recorded is irradiated with excitation light in the main direction, and the stimulable phosphor sheet is stored. The reading section for reading the stimulated emission light emitted from the sheet and the stimulable phosphor sheet are relatively conveyed in the sub-direction substantially orthogonal to the main direction.

At that time, the natural frequency fn1 (Hz) of the stimulable phosphor sheet and the conveying speed Vr (mm / s) in the sub direction.
And fn1 / Vr ≧ 0.8 or fn1 / Vr ≦ 0.
The material of the support that constitutes the stimulable phosphor sheet, the thickness of the support, and the fixing condition of the stimulable phosphor sheet are set so as to satisfy the relationship of 2.

It is generally known that the visibility varies depending on the spatial frequency, and it is necessary to reduce the visibility of the vibration unevenness in order to perform a highly accurate reading process. Therefore, the natural frequency fn1 (Hz) of the stimulable phosphor sheet
And the conveyance speed Vr (mm / s) in the sub-direction are used to set a relationship in which vibration unevenness is hard to be visually recognized. Specifically, in the range of 0.2 <fn1 / Vr <0.8, the vibration unevenness is easily visible, and the relationship of fn1 / Vr ≧ 0.8 or fn1 / Vr ≦ 0.2 must be satisfied. As a result, it becomes difficult for the uneven vibration to be visually recognized. This makes it possible to perform highly accurate and efficient reading processing with a simple configuration.

Further, the reading section is provided with a light collecting system provided with a CCD, so that the size of the whole apparatus can be reduced and the reading process can be speeded up easily. Where CCD
Therefore, it is necessary to suppress the variation in the distance between the stimulable phosphor sheet and the light collecting system to be small. At that time, fn1 / V
By satisfying the relation of r ≧ 0.8, the flatness of the stimulable phosphor sheet can be maintained by the rigidity of the stimulable phosphor sheet itself. Therefore, the replacement work of the stimulable phosphor sheet can be easily and favorably performed.

[0014]

1 is a schematic configuration diagram of a radiation image information recording / reading apparatus (image information reading apparatus) 10 according to a first embodiment of the present invention.

The radiation image information recording and reading apparatus 10 temporarily records a radiation image of a subject H such as a human body on the stimulable phosphor sheet IP, and a main direction (with respect to the stimulable phosphor sheet IP). A reading unit (scanning unit) 14 that irradiates excitation light L such as laser light in the X direction) and photoelectrically reads stimulated emission light R emitted according to the intensity of the radiation.
A sub-scanning system 16 that conveys the reading unit 14 in a sub-direction (direction of arrow Y) substantially orthogonal to the main direction; 18 and. The stimulable phosphor sheet IP is basically composed of a support, a phosphor layer and a protective film.

The radiation recording section 12 is provided with a radiation source 20 for generating the radiation S, and a radiation transmissive imaging table 22 for holding the subject H at a predetermined position. 1 and 2
As shown in FIG.
3 and a grid 24 for removing scattered radiation are arranged. Further behind the grid 24, the stimulable phosphor sheet IP is held at a predetermined photographing position via a fixing portion 26.

As shown in FIG. 2, the frame member 28 constituting the fixed portion 26 is arranged in the arrow Y direction which is a sub direction (sub scanning direction) substantially orthogonal to the main direction of the excitation light L (arrow X direction). A pair of support bases 30 that extend and are located on both ends of the stimulable phosphor sheet IP in the arrow X direction and arranged in parallel with each other are fixed. As shown in FIG. 3, each support base 30 is provided with a reference surface 30a extending in the arrow Y direction, and both ends in the lateral direction of the stimulable phosphor sheet IP are arranged on the reference surface 30a. A predetermined escape T is formed between both end faces of the stimulable phosphor sheet IP and each support base 30 in consideration of expansion of the stimulable phosphor sheet IP.

On each support base 30, in order to press and support both end portions of the stimulable phosphor sheet IP on the reference surface 30a,
A plurality of (for example, 6 each) leaf springs 32 are mounted corresponding to predetermined positions. Incidentally, the stimulable phosphor sheet I
The structure is not limited to the leaf spring 32 as long as it can hold both ends of P, and various structures can be adopted.

As shown in FIGS. 1 and 2, the reading section 14 includes an excitation system 36 and a CCD line sensor (photoelectric conversion means) 40 provided with a condenser lens array 38. Optical lens array 38 and the C
The CD line sensor 40 extends in the main direction and is attached to the scanner head 42.

The pumping system 36 comprises a plurality of laser diodes 44 arranged in the main direction (direction of arrow X). The laser diode 44 is arranged such that the excitation light emission side is away from the stimulable phosphor sheet IP, and the excitation light in the divergent light state emitted from the laser diode 44 is reflected by the cylindrical mirror 46 and excited. As the light L, the stimulable phosphor sheet IP is linearly irradiated in the main direction.

As shown in FIG. 2, the sub-scanning system 16 includes a rotary drive source 50 arranged at one end side in the arrow Y direction, and both ends of a rotary shaft 52 extending from the rotary drive source 50 in the arrow X direction. A drive pulley 54 is fixed to the. Each drive pulley 5
4, a driven pulley 56 is arranged at a predetermined distance in the direction of the arrow Y, and a belt 58 is stretched over the driven pulley 56 and the drive pulley 54. The scanner head 42 is fixed to the belt 58, and
2 is supported by a pair of guide rails 60 extending in the arrow Y direction.

The erasing light source section 18 comprises a stimulable phosphor sheet I.
It is arranged so as to face P with the reading unit 14 in between (see FIGS. 1 and 2). The erasing light source unit 18 irradiates the stimulable phosphor sheet IP with erasing light Q to release the radiation energy remaining in the stimulable phosphor sheet IP. The erasing light source unit 18 is a stimulable phosphor sheet IP.
Fluorescent lamp 68 having a length equal to or greater than the width direction (direction of arrow X) of the
Are arranged in the lengthwise direction of the stimulable phosphor sheet IP (direction of arrow Y), and the erasing light Q is applied to the entire image area of the stimulable phosphor sheet IP. .

The operation of the radiation image information recording / reading apparatus 10 thus constructed will be described below.

First, at the natural frequency fn1 (Hz) of the stimulable phosphor sheet IP and the conveyance speed Vr (mm / s) of the scanner head 42 in the sub-direction (direction of arrow Y),
FIG. 4 shows a nonuniformity visual recognition curve M regarding fn1 / Vr and subscanning conveyance nonuniformity. This unevenness visual recognition curve M indicates the boundary of whether or not the transport unevenness is visually recognized, and in practice, the uneven vibration is easily visible in the range of 0.2 <fn1 / Vr <0.8.

Therefore, in the first embodiment, fn1 / V
The material (Young's modulus or specific gravity) of the support that constitutes the stimulable phosphor sheet IP, the thickness of the support, and the storage so that the relationship r ≦ 0.2 or fn1 / Vr ≧ 0.8 is satisfied. Conditions for fixing the fluorescent phosphor sheet IP are set.

Therefore, for example, the transport speed Vr is 100 m.
In the case of m / s, the natural frequency fn1 ≧ 80 Hz or the natural frequency fn1 ≦ 20 Hz. At that time, in order to maintain the flatness of the stimulable phosphor sheet IP, fn1 ≧ 80
It is desirable to set to Hz. Furthermore, considering the influence of external vibration, for example, the vibration of a general motor that constitutes the rotary drive source 50 is often used at 100 Hz to 120 Hz, so the natural frequency fn1 ≧ 150 Hz.
It is desirable to set to.

On the other hand, as the support of the stimulable phosphor sheet IP, for example, glass (Young's modulus: 73 GPa, specific gravity: 2.5) is used. This stimulable phosphor sheet I
The dimension of P is 415 mm × 450 mm, and the fixed portion 2
On the other hand, a structure in which two long sides of both ends in the lateral direction of the stimulable phosphor sheet IP are held is adopted.

If the support of the stimulable phosphor sheet IP has a thickness of 5 mm, the stimulable phosphor sheet IP is
When the natural frequency fn1 of the above is 68 Hz and the thickness of this support is 13 mm, the stimulable phosphor sheet IP
The natural frequency fn1 of is 156 Hz. This allows
By using the stimulable phosphor sheet IP having a support having a thickness of 13 mm, it is possible to satisfy the condition of natural frequency fn1 ≧ 150 Hz.

Next, in order to record the radiation image information, as shown in FIG. 1, when the patient moves to the radiation recording section 12 side, the recording position is adjusted by raising or lowering the imaging table 22 by the operation of a doctor or the like. Be seen. Further, the radiation source 20 is driven by a doctor or the like in a state where the subject H, which is the affected part of the patient, is arranged corresponding to the imaging table 22. The radiation output from the radiation source 20 passes through the subject H and reaches the stimulable phosphor sheet IP, whereby radiation image information is recorded on the stimulable phosphor sheet IP.

After the radiation image information of the subject H is recorded on the stimulable phosphor sheet IP, the excitation system 36 constituting the reading section 14 is driven and the rotary drive source 50 constituting the sub-scanning system 16 is driven. To be done. In the excitation system 36, a plurality of laser diodes 44 arranged in the main direction (arrow X direction) of the stimulable phosphor sheet IP are driven, and the excitation light output from the laser diodes 44 and reflected by the cylindrical mirror 46 is excited. L is irradiated to the stimulable phosphor sheet IP along the arrow X direction.

On the other hand, under the driving action of the rotary drive source 50 which constitutes the sub-scanning system 16, the drive pulley 5 is driven through the rotary shaft 52.
4 rotates, the drive pulley 54 and the driven pulley 56
Under the action of the belt 58 running around the
The scanner head 42 fixed to the belt 58 moves in the arrow Y direction. Therefore, the stimulable phosphor sheet IP on which the radiation image information is accumulated is two-dimensionally scanned by the excitation light L, and the stimulable phosphor sheet IP emits the stimulated emission light R according to the radiation image information. Emit.

This stimulated emission light R is collected by the condenser lens array 3
It is incident on the CCD line sensor 40 via 8. When the stimulated emission light R enters the CCD line sensor 40,
The stimulated emission light R is converted into an electric signal, and the radiation image information of the stimulable phosphor sheet IP is photoelectrically read.

Next, the erasing light source section 18 is applied to the stimulable phosphor sheet IP from which the radiation image information has been read.
The erasing light Q is emitted from the fluorescent lamp 68 constituting the above. Therefore, the radiation energy remaining on the stimulable phosphor sheet IP is released, and the stimulable phosphor sheet IP is used for the next imaging.

In this case, in the first embodiment, the stimulable phosphor sheet IP is supported at both ends in the main direction (arrow X direction) via the fixing portions 26 extending in the sub direction (arrow Y direction). In addition, the thickness of the glass support that constitutes the stimulable phosphor sheet IP is set to 13 mm.

When the scanner head 42 moves in the arrow Y direction at a reading speed of 100 mm / s, the natural frequency fn1 of the stimulable phosphor sheet IP is 156 Hz, which satisfies the condition of natural frequency fn1 ≧ 80. ing.
Therefore, even when vibration occurs in the stimulable phosphor sheet IP during reading by the scanner head 42, this vibration unevenness is not visually recognized (see FIG. 4).

As a result, a highly accurate and efficient reading process can be performed with a simple structure, and the stimulable phosphor sheet I can be read.
There is an effect that a clear image can be surely obtained from P. Moreover, by satisfying fn1 / Vr ≧ 0.8, the flatness of the stimulable phosphor sheet IP itself can be effectively maintained.

Therefore, as in the case of using the CCD line sensor 40, the stimulable phosphor sheet IP and the C
It can be effectively adopted even when the distance variation from the CD line sensor 40 is kept within 100 μm or less in the plane. Moreover, there is an advantage that the work of exchanging the stimulable phosphor sheet IP can be easily and favorably performed.
As the support for the stimulable phosphor sheet IP, ceramics, metals such as aluminum may be used in addition to glass.

FIG. 5 is a schematic perspective explanatory view of a fixed portion 80 which constitutes a radiation image information recording / reading apparatus (image information reading apparatus) according to the second embodiment of the present invention. The same components as those of the fixed unit 26 constituting the radiation image information recording / reading apparatus 10 according to the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

The fixed portion 80 is orthogonal to the support base 30,
The stimulable phosphor sheet IP is provided with a pair of support bases 82 located on both ends in the arrow Y direction and arranged parallel to each other. Each support base 82 is provided with a reference surface 82a extending in the arrow X direction, and both longitudinal ends of the stimulable phosphor sheet IP are arranged on the reference surface 82a. A predetermined escape T is formed between both end surfaces of the stimulable phosphor sheet IP and each support base 82 in consideration of expansion of the stimulable phosphor sheet IP.

In order to press and support both longitudinal ends of the stimulable phosphor sheet IP to the reference surface 82a, each of the support bases 82 corresponds to a substantially central portion of the stimulable phosphor sheet IP. A leaf spring 84 is attached. The stimulable phosphor sheet IP has two long sides held by the support base 30 and the leaf springs 32, and the support base 80.
The leaf spring 84 holds the two short sides.

Therefore, in the second embodiment, if the thickness of the support of the stimulable phosphor sheet IP is set to 8 mm,
The natural frequency fn1 of this stimulable phosphor sheet IP is 15
It becomes 5 Hz. Therefore, when the fixing portion 80 that holds the two long sides and the two short sides of the stimulable phosphor sheet IP is used, the stimulable phosphor sheet IP in which the thickness of the support is set to 8 mm is adopted. By doing so, the influence of external vibration caused by the rotary drive source 50 and the like that configures the sub-scanning system 16 is eliminated, so that it is difficult to visually recognize vibration unevenness. That is,
In the second embodiment, the same effects as those of the first embodiment can be obtained, such as a clear radiation image in which vibration unevenness is not noticeable can be reliably obtained.

Here, using the stimulable phosphor sheet IP in which the thickness of the support is set to 5 mm, each of the fixing portions 2 is used.
6 and 80, the fixed part 26 has a natural frequency f
While n1 is 68 Hz, the natural frequency fn1 of the fixed portion 80 is 126 Hz. Therefore, a support having a thickness of 5 mm cannot satisfy the condition of natural frequency fn1 ≧ 150 Hz, but by adopting the fixing portion 80, the natural frequency fn1 can be improved.

In the first and second embodiments, the stimulable phosphor sheet IP is held in a vertical posture and the radiation image information carried by the stimulable phosphor sheet IP is read vertically. Although the radiation image information recording and reading apparatus 10 of the type has been described, for example, a horizontal type apparatus that holds the stimulable phosphor sheet IP in a horizontal posture and performs the reading process of the radiation image information may be used.

In the first and second embodiments, the radiation image information recording / reading apparatus 10 is used as the image information reading apparatus.
However, the present invention is not limited to this,
The present invention can also be applied to an apparatus that reads a radiation image information by loading a stimulable phosphor sheet IP on which radiation image information is recorded by a radiation image information recording apparatus formed separately.

[0045]

In the image information reading apparatus according to the present invention, the natural frequency fn1 (Hz) of the stimulable phosphor sheet and the conveying speed Vr (mm / s) in the sub direction are fn1 / Vr ≧.
0.8 or fn1 / Vr ≦ 0.2, so that the material of the support constituting the stimulable phosphor sheet,
The thickness of the support and the conditions for fixing the stimulable phosphor sheet are set. As a result, it is possible to perform highly accurate and efficient reading processing with a simple configuration in which vibration unevenness is hard to be visually recognized.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a radiation image information recording / reading apparatus according to a first embodiment of the present invention.

FIG. 2 is an exploded perspective view of an internal structure of the radiation image information recording / reading device.

FIG. 3 is an enlarged cross-sectional explanatory view of a main part of a fixed part that constitutes the radiation image information recording / reading device.

FIG. 4 is an explanatory diagram of an unevenness visual recognition curve.

FIG. 5 is a perspective view for explaining a main part of a fixed part which constitutes a radiation image information recording / reading apparatus according to a second embodiment of the present invention.

FIG. 6 is a cross-sectional explanatory view of main parts of a radiation image information reading device according to a conventional technique.

[Explanation of symbols]

10 ... Radiation image information recording / reading apparatus 12 ... Radiation recording section 14 ... Reading section 16 ... Sub-scanning system 18 ... Erasure light source section 20 ... Radiation source 22 ... Imaging table 26, 80 ...
Fixed parts 30, 82 ... Support bases 30a, 82
a ... Reference planes 32 and 84 ... Leaf spring 36 ... Excitation system 40 ... CCD line sensor 42 ... Scanner head 44 ... Laser diode 50 ... Rotation drive source 68 ... Fluorescent lamp IP ... Accumulable phosphor sheet

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H04N 1/04 H04N 1/04 EF term (reference) 2G083 AA03 BB02 BB04 CC04 CC10 DD11 EE02 EE07 2H013 AC01 AC04 AC05 AC11 5B047 AA17 AB02 BA02 BB02 BC05 BC09 BC11 BC14 BC18 CA07 CB07 5C072 AA01 BA02 BA04 CA06 DA03 DA04 EA05 MB02 NA05 VA01

Claims (2)

[Claims] 1. A stimulable emission light emitted from the stimulable phosphor sheet by irradiating the stimulable phosphor sheet on which radiation image information of an object is stored and recorded in a main direction with the excitation light. An image information reading apparatus that relatively conveys a reading unit for reading the stimulable phosphor sheet and the stimulable phosphor sheet in a sub-direction substantially orthogonal to the main direction, wherein a natural frequency fn1 (of the stimulable phosphor sheet ( Hz)
And the conveyance speed Vr (mm / s) in the sub-direction are fn
The material of the support constituting the stimulable phosphor sheet, the thickness of the support, and the stimulable phosphor sheet so that the relationship of 1 / Vr ≧ 0.8 or fn1 / Vr ≦ 0.2 is satisfied. The image information reading device is characterized in that the fixed condition of is set. 2. The image information reading apparatus according to claim 1, wherein the reading unit includes a light collecting system provided with a CCD.