JPH0813080B2 - Radiation image information reader - Google Patents

Description

TECHNICAL FIELD The present invention relates to an apparatus for reading image information of a stimulable phosphor panel recorded by irradiation with radiation such as X-rays.

[Prior art]

As an image reading device of this kind, a photostimulable phosphor panel in which image information of a human body or the like is previously recorded by irradiating X-rays is scanned and irradiated with excitation light to excite a phosphor, thereby causing photostimulated luminescence. An apparatus is known in which light is guided to a photoelectric conversion element by a photoconductor to read image information.

However, an ordinary photoconductor is a system in which stimulated emission light is incident on the end face thereof, and it is difficult to efficiently collect the generated stimulated emission light. In addition, a part of the stimulated emission light that is to be photoelectrically converted by being incident on the photoconductor may be emitted again from the photoconductor to the outside to be a so-called loss component, resulting in a reduction in light collection efficiency.

[Object of the Invention] An object of the present invention is to improve the light collection efficiency of photostimulated luminescence light generated from a photostimulable phosphor panel.

[Structure of Invention]

For this reason, the present invention is a radiation stimulable phosphor panel recording the radiation image information is scanned with excitation light, the radiation stimulating luminescence from there In the image information reading device, it has a rod shape, at least a part of which is arranged so as to face the panel along the scanning line of the scanning, transmits the excitation light, and contains a fluorescent substance for wavelength conversion inside. , A photoconversion conductor that emits light whose wavelength is converted by entering the stimulated emission light from the side surface, and reflects the stimulated emission light on the side opposite to the side surface of the light conversion conductor. And a reflecting member that transmits the excitation light.

〔Example〕

Examples of the present invention will be described below. FIG. 1 is a block diagram showing an outline of an entire apparatus for carrying out the present invention. In the present embodiment, an X-ray irradiator 2 is provided on the back of a subject 1 such as a human body, a grid 3, a photo timer 4, and a stimulable phosphor panel 5 are sequentially arranged in front, and the stimulable phosphor panel 5 is arranged. On the other hand, the X-ray transmission image of the subject 1 is recorded as fluorescence accumulated energy. Grid 3
Is for obtaining an accurate X-ray image by blocking X-rays incident (reflected or scattered by others) from other than from the direction of the X-ray irradiator 2, and the photo timer 4 is the irradiation accumulation amount of X-rays. Is detected to control the X-ray irradiator 2.
The X-ray irradiator 2, the grid 3, the photo timer 4 and the like described above constitute a recording portion.

On the other hand, the reading portion deflects (scans) the light beam from the beam light source 6 using a semiconductor laser or the like by the deflector 7, scans the stimulable phosphor panel 5 via the mirror 8 or the like, and scans the scanning. A filter 10 is provided which converts the stimulated emission light generated in the light spot portion into a wavelength that can be easily handled by the rod-shaped light conversion conductor 9 and removes the light generated in the light conversion conductor 9 from other light. Via PMT (photomultiplier) 11 via photoelectric conversion, after amplifying with amplifier 12, after converting into digital signal with A / D converter 13, the digital signal is sent to an image processing circuit (not shown) to obtain a read image I am trying. 14 is an erasing lamp, which is turned on to emit a stimulable phosphor panel 5.
By scanning, the energy remaining after the reading scan of the panel 5 is released / erased.

FIG. 2 is a structural block diagram showing the reading portion in more detail. The beam light source 6 is provided with a collimator lens, and the light beam from there is shaped into a beam shape by a beam shaper 15, passes through a mirror 16 and a filter 17, and is deflected by a deflector 7.
It is scanned by the galvano mirror 18 as. Then, the scanned beam passes through the fθ lens 19, the optical path is changed by the mirror 8, and the beam is incident on the stimulable phosphor panel 5 as excitation light. The above-mentioned light conversion conductor 9 has a rod shape arranged in a direction along the scanning direction of the excitation light and in parallel therewith so as to cover the scanning line on the stimulable phosphor panel 5, and its both ends. A PMT 11 is coupled to the filter via a filter 10. 20 is a power supply for PMT11. Reference numeral 21 is a current / voltage conversion circuit that converts the current signal obtained by the PMT 11 into voltage, and 22 is an adder that adds the voltage signals obtained by both current / voltage conversion circuits 21. Reference numeral 24 is a logarithmic amplifier for logarithmically amplifying the output of the amplifier 12, 25 is a filter for removing noise components, and 26 is a sampling and holding circuit for sampling the read image signal in pixel units. Further, an optical sensor 27 such as a photodiode for detecting the scanning beam light is arranged at one end of the stimulable phosphor panel 5, and a horizontal synchronizing signal obtained by the optical sensor 27 (one time of excitation light One pallet appears in the main scan.) Is input to the timing signal generation circuit 28 which determines the processing timing. This timing signal generation circuit
The signal from 28 is output to the sampling and holding circuit 26, the A / D converter 13, the driver 29 that controls the light beam generator 6, the galvanometer mirror driver 30, and the like.

As shown in FIG. 3, the above-mentioned light conversion conductor 9 has a property of generating light of another wavelength from the inside in the end face direction by the light incident from the side surface, and is a stimulable phosphor panel. By arranging the panel 5 so as to face it, the stereoscopic light receiving angle from the stimulated emission point of the panel 5 becomes extremely large, and the light collection efficiency becomes large. This light conversion conductor 9 is also called a fluorescent optocollector (trade name), and is made by mixing and mixing a special fluorescent substance in transparent plastic such as acrylite, polycarbonate, polystyrene under specific conditions. Most (80%) of the fluorescence generated inside due to light incident from the outside is guided to both end face portions according to the law of total internal reflection, and is emitted in a dense state. In this embodiment, the excitation light lambda ₂ emitted light lambda ₃ generated from the stimulable phosphor panel 5 is excited by _{(= 500nm~2,000nm, 700nm~800nm} in light of the semiconductor laser) ₍₌ 200 nm to 500 nm ) Is received from the side surface, converted into light of another wavelength λ ₄ (= 400 nm to 2,000 nm), emitted from both end surfaces, and passed through the filter 10.
It is incident on PMT11. FIG. 4 is a diagram showing wavelength conversion characteristics of the light conversion conductor 9, FIG. 4 (a) is an example of the spectrum of incident light, and FIG. 4 (b) is an example of the spectrum of emitted light. Facing the photostimulable phosphor panel 5, this light conversion conductor 9
, The excitation light component passes through the light conversion conductor 9, so that it does not enter the PMT 11 and the S / N is improved.

As shown in FIG. 5, if a mirror 31 is formed on one end surface of the light conversion conductor 9 by silver plating or the like, only one PMT 11 attached to the other end side can be used as shown in FIG. It is possible to collect the emitted light λ ₄ converted there with the same efficiency as.

As the light conversion conductor 9, as shown in FIG.
The core 9a having a high refractive index inside, the clad 9b having a low refractive index is provided outside the core 9a, and a composite structure of different media in which a fluorescent substance is mixed on the inner core 9a side of the core 9a, the cladding 9b As shown in FIG. 7, the output light λ ₄ after conversion can be led to both ends without being affected by dirt, scratches, etc.,
The light collection efficiency is significantly improved. In FIG. 7, 9c is a fluorescent substance.

In this case, n ₁ the refractive index of the core 9a, when the refractive index of the cladding 9b and n _2, the light receiving and emission angle and numerical aperture ^{_{NA, NA = (n 1 2 -n}} 2 2) 1/2 light and emitted Angle = 2sin ^-1 (NA).

In addition, as shown in FIG. 8, the light conversion conductor 9 has a linear portion at a position along the scanning direction of the excitation light of the stimulable phosphor panel 5, and has one end at each end. of
It may be bent so as to lead to the PMT 11, or as shown in FIG. 9, it may be similarly arranged as a focused light conversion conductor 9'in which a plurality of small diameter light conversion conductors are bundled.

On the other hand, as a method of making the excitation light λ ₂ incident, as shown in FIG.
In addition to the method of allowing the light to enter from an oblique direction as shown in (d) to (d), there is the method of making the light to enter from directly above as shown in the parts (e) to (h). In the former case, a gap for passing the excitation light λ ₂ is formed in a part of the light conversion conductors 9 and 9 ′, if necessary. In the latter case, two light conversion conductors 9 are arranged.
Alternatively, the excitation light is allowed to pass between the adjacent portions immediately above 9 '.

Further, in order to improve the incidence efficiency of the photostimulated luminescent light generated from the stimulable phosphor panel 5 to the light conversion conductor,
As shown in FIG. 11, the photostimulated luminescent light reflecting member 32 is attached to the back surface of the light conversion conductor (the side opposite to the side facing the stimulable phosphor panel 5) so as to be in close contact with or separated from it. This reflective member
When 32 is brought into close contact with a plurality of small-diameter focused light conversion conductors 9 ', it also functions as a bundle of the conductors 9'.
Further, the reflecting member 32 is made of a material having a transmissive property with respect to the excitation light, and the excitation light is prevented from being reflected there and returning to the stimulable phosphor panel 5, so that the read image quality interferes with the excitation light. So that it will not be deteriorated. FIG. 12 is a diagram showing an example of a light conversion conductor to which such a reflecting member 32 is attached.

FIG. 13 is a view showing an example in which the photoconversion conductors 9 or 9'are arranged on both front and back surfaces of the stimulable phosphor panel 5. The stimulable phosphor panel 5 is not limited to the side irradiated with excitation light,
Since stimulated emission light is also generated from the opposite surface, by arranging the light conversion conductor on the opposite side, the light collection efficiency can be greatly improved.

〔The invention's effect〕

As described above, in the present invention, since the side surface of the light conversion conductor is arranged along the scanning line of the panel, the stereoscopic light receiving angle from the stimulated emission point of the panel becomes extremely large, and the light collection efficiency is large. Become.

In addition, this photoconversion conductor converts the wavelength of the stimulated emission light incident from the side surface thereof by the wavelength conversion fluorescent substance inside and emits it from the end face, so that the wavelength conversion fluorescent substance is set appropriately. As a result, the wavelength can be converted to a wavelength that makes the photoelectric conversion efficiency of the photoelectric conversion element provided on the end face favorable, and an electric signal corresponding to the generated stimulated emission light can be obtained with high efficiency.

Furthermore, since the excitation light that excites the panel passes through this light conversion conductor, it does not enter the photoelectric conversion element on the end face due to reflection or the like at this light conversion conductor, and S / N deterioration due to the excitation light occurs. Can be prevented.

Further, since the reflecting member reflects the stimulated emission light and transmits the excitation light, the efficiency of concentrating the stimulated emission light is further improved, and the S / N deterioration due to the reflection of the excitation light is also observed from this aspect. Can be prevented.

As described above, in the present invention, an extremely minute level of stimulated emission light generated from the stimulable phosphor panel by being excited by the excitation light, by using the light conversion conductor and the reflection member, high conversion efficiency It is possible to convert the signal into an electric signal at the same time, and at the same time, it is possible to effectively prevent the S / N deterioration due to the excitation light by preventing the excitation light from being reflected by the optical conversion conductor and the reflection member. Further, if the reflecting member is also used as a holding member for the photoconductor, space saving and low cost can be realized.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an image information recording / reading device showing the principle of the present invention, FIG. 2 is a more detailed block diagram of a reading device portion, FIG. 3 is an explanatory view of a light conversion conductor, and FIG. a),
(B) is a characteristic diagram of the light conversion, FIG. 5 is an explanatory diagram of another method of condensing light from the light conversion conductor, FIG. 6 is an explanatory diagram of a composite structure of the light conversion conductor, and FIG. The figure is an explanatory view of the operation of the light conversion conductor shown in FIG. 6, and FIGS. 8 and 9 are illustrations of connecting both ends of the light conversion conductor to one PMT, and FIGS.
11 (a) and 11 (b) are explanatory views of the excitation light irradiation, FIG. 11 (a) and FIG. 11 (b) are explanatory views in which a reflection member is attached to the light conversion conductor for improving the efficiency of concentrating stimulated emission light, and FIG. (A) to (h) are explanatory views in each case, and FIG. 13 is an explanatory view in which a photoconversion conductor is arranged on the upper and lower surfaces of the stimulable phosphor panel. 1 ... Subject, 2 ... X-ray generator, 3 ... Grid, 4
...... Photo timer, 5 ...... Photostimulable phosphor panel, 6 ......
Light beam generator, 7 ... Deflector, 8 ... Mirror, 9 ...
Optical conversion conductor, 10 …… filter, 11 …… PMT, 12 …… amplifier, 13 …… A / D converter, 14 …… erasing lamp, 15 …… beam shaper, 16 …… mirror, 17 …… Filter, 18 …… Galvano mirror, 19 …… fθ lens, 20 …… Power supply for PMT, 2
1 ... Current / voltage conversion circuit, 22 ... Adder, 24 ... Logarithmic amplifier, 25 ... Filter, 26 ... Sampling hold circuit, 27 ... Horizontal synchronization signal sensor, 28 ... Timing generation circuit, 29 ... … Light beam generator driver, 30 …… Galvano mirror driver, 31 …… Mirror, 32 …… Light reflecting member.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G06T 1/00 H04N 1/19 7517-2J A61B 6/00 303 K H04N 1/12 101 G06F 15 / 64 B

Claims (1)

[Claims] 1. A radiation image obtained by scanning a photostimulable phosphor panel having radiation image information recorded thereon with excitation light and collecting and stimulating the photostimulated luminescence light from the panel for photoelectric conversion. In the information reading device, a rod shape, at least a part of which is arranged to face the panel along the scanning line of the scanning, transmits the excitation light, and contains a fluorescent material for wavelength conversion inside, A light conversion conductor that emits light whose wavelength is converted by entering the stimulated emission light from a side surface, and reflects the stimulated emission light on the side opposite to the side surface of the light conversion conductor. A radiation image information reading device comprising: a reflecting member that transmits excitation light;