JPS58121874A - X-ray image converter - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an X-ray image converter equipped with a scanning excitation device and a device for converting an image signal sequence obtained by scanning into visible 1'l. This type of X-ray image reproducing device is, for example, a patent issued in Europe 15Ji@Qo225a.
It is known by No. a.

A two-dimensional X-ray image with high contrast and spatial resolution, which is limited primarily by the X-ray dose, is produced primarily by the following two methods. One of these is an X-ray photography method that uses a computer, and the other methods include, for example, five methods in which an X-ray distribution image stored in a phosphorescent material is excited to emit light. In the first method, the object is irradiated with a fan-shaped beam;
The generated signal is recorded on a linear detector array f. This requires expensive equipment containing about 500 to 1000 detectors and amplifiers. Moreover, the scanning time of the area to be inspected is about 10 seconds, which is significantly longer than the normal imaging time (about milliseconds). Furthermore, due to the long scanning time, the 9 load of the X-ray tube becomes significantly higher, and the movement of the extraneous object may cause blurring of the image. Moreover, the spatial resolution expressed in terms of the number of cycles per fermentation is 0.5 to 0.05 per/, tm, which is lower than 4 to 8 per/8 #l for normal imaging.

In the second method of exciting the luminescent screen to emit light, a large optical loss occurs between the luminescent screen and the recording system connected thereto due to the electron multiplier tube. Therefore, it is absorbed at the input end of the intensifier tube, which fixes the luminescent screen and the intensifier tube and moves the scanning beam. The number of photons per X gland quantum decreases.

When the photomultiplier tube is brought close to the luminescent screen, the solid angle between the luminescent element and the electron multiplier tube will increase depending on the location unless the luminescent screen or electron multiplier tube is moved.
The signal becomes unclear. In this case, it would be more effective to move the luminescent screen. To do this, the luminescent screen is wound around a drum, for example, and this drum is rotated and simultaneously moved in the axial direction. Even with this configuration, a significant portion of the signal is lost and additional mechanical separation is added.

The object of the invention is to improve the X-ray image converter mentioned at the outset so that a high signal yield can be achieved with a simple construction. This purpose is the first claim.
This is achieved by adopting the structure listed as the feature in section 2. Advantageous embodiments of the invention are indicated in the following claims.

It consists of an X-ray transparent electrode, an X-ray excited luminescent layer (a layer that retains photoelectrons generated by X-ray irradiation) provided thereon, a photoconductive semiconductor layer that is sensitive to the generated light, and an electrode following this layer. If you use a device in which at least one electrode and possibly the semiconductor layer following it are transparent to the light emitting layer excitation light, the semiconductor layer will be in direct contact with the light emitting layer, so the light will be emitted in the gap between the light receiving device and the light emitting layer. No loss of light occurs. Moreover, this device is easy to manufacture since it is made by simply superposing layers. The storage layer material is, for example, barium fluoride chloride (BaFCI:Eu) activated with Eu.
) is used. The photoconductive semiconductor can be selected from a group of perforated semiconductors. Oxides, sulfides and selenides of zinc and arsenic are also used, and silicon and gallium arsenide can also be used. The thickness of the storage layer needs to be a few multiples of 100 μm in order to achieve sufficient XS conversion, but since the semiconductor layer only needs to absorb light, the thickness may be 10 to 20 μm.

To reproduce the X41 image stored in the light emitting layer, a combination of the light emitting layer and an infrared transparent flat photoconductive semiconductor is used. This combination can be made, for example, by precipitating the luminescent material together with a binder onto the photoconductor. After accumulating a XiI image on this combination, it is scanned with a laser beam, and the resulting image signal train is taken out from the electrodes. Visualization of this signal train is performed by a known XW television device.

In addition to the laser beam scanning type, a type in which an appropriate light emitting diode array is used and the light emitting diodes are sequentially scanned can be used for light emission excitation. If the photoconductive semiconductor layer has a large capacitance and causes additional noise, the transparent electrode above it can be divided, for example into parallel strips.

The invention will be explained in more detail with reference to the embodiments shown in the drawings.

In FIG. 1, 1 is an X-ray source, which is shown in the form of an X-ray tube. The X-ray beam 2 emitted from this X-ray source passes through the receiver 3 and hits the imaging layer 4 . This imaging layer is composed of an X-ray transparent support plate 5, an Eu-activated barium fluoride chloride (BaF, C1:Eu) layer 6 (thickness about 100 μm thick) and a semiconductor layer 7 attached thereon. Light-transmissive electrodes 8 and 9 are provided on both sides. The electrodes 9 face the laser light beam scanning device 10 with a certain spacing therebetween. Conductive wires 11 a and '1 l b are connected to the electrode 8.9,
These conductors are connected to a DC power source 13 through a resistor 12. The conductors 1xa, xxb are further connected to an amplifier 14 of a television reproduction device 15.

The X-ray beam 2 from the K-ray source 1 is transmitted through the phosphorescent layer 6, and an energy distribution image corresponding to the perspective image is accumulated in the phosphorescent layer 6. When the voltage of the power source 13 is applied through the conductors tla and llb, the light beam 16 emitted from the light source 0 is guided through the transparent heavy layer 9 to scan the semiconductor layer 7 and release the energy stored in the layer into the light. be rescued in the form of This light changes the electrical conductivity of the layer depending on its intensity, so an electrical signal is created depending on the applied voltage. This electrical signal is transmitted to amplifier 1
4 to a television receiver, creating a visible image on its screen. Since the television device 17 is provided with adjustment means for brightness, contrast, trust, etc., the projected image can be adapted to specific requirements.

FIG. 2 shows an embodiment in which a light emitting diode array (20) is used in place of the scanning light source IO.

Each light emitting diode 21 of this array is controlled by a control device 23 through a conductor system 22 so that it sequentially emits light. Other operations correspond to those of the embodiment of FIG.

[Brief explanation of the drawing]

1 and 2 each show a different embodiment of the invention. DESCRIPTION OF SYMBOLS 1... X-ray source, 5... Support plate, 6... Phosphorescent layer, Ma... Semiconductor layer, 8 and 9... Transparent type -
pole, 10... scanning light beam device, 20...
- Light emitting diode array.

Claims (1)

[Claims] ]) A light-emitting screen is placed on a photoconductive semiconductor layer which is sensitive to the emitted light, and this photoconductive semiconductor layer is placed between two electrodes. A stratified structure containing F ei #I originating from at least one side
1. An X-ray image converter equipped with an X-ray image converter and a device that converts an image signal sequence obtained by scanning into a visible image. 2) Light Emission - An X-ray image converter mounted on a self-mounted X-ray image converter, characterized in that the electrode in contact with the barrel is transparent to scanning light. 3) The xi image computer according to claim 1, wherein the photoconductive semiconductor layer and the electrode in contact with the outside thereof are substantially transparent. 4) The X-ray image converter according to claim 1, characterized in that a light emitting diode array is provided as a layered structure including a light emitting screen of the excitation tail generator.