JPH04186484A - Radiation image reader - Google Patents

Abstract

PURPOSE:To prevent the reproducibility of a radiation image from being lost even if uneven sensitivity or uneven radiation exists by previously storing image unevenness information and correcting radiation image information read out from a radiation image converting panel based upon its corresponding image unevenness information. CONSTITUTION:The correction data of sensitivity unevenness of each stimulable phosphor plate 5 are previously stored in a magnetic tape 21 corresponding to an image unevenness information storing means. Data for correcting the unevenness of X ray radiation quantity of each X-ray radiator 3 are previously stored in a non-volatile memory built in a radiation image processor 9. The processor 9 corrects the radiation image data of each image unit read out from a plate 5 based upon these correction data in accordance with two kinds of correction data corresponding to each picture element. Consequently the accuracy of a radiation image can be prevented from being lost due to sensitivity unevenness and dosage unevenness.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a radiation image reading device, and more particularly to a technique for correcting image unevenness in a device for reading radiation image information stored and recorded in a stimulable phosphor.

<Conventional technology> Radiographic images such as X-ray images are often used for disease diagnosis. irradiate,
This generated visible light, which was then irradiated onto a film using silver salt to develop the film, similar to ordinary photography.
So-called radiography has been widely used.

However, in recent years, methods have been devised to read images directly from the phosphor layer without using a film coated with silver salt.

In this method, the radiation transmitted through the subject is absorbed by the stimulable phosphor, and then the stimulable phosphor is excited with light or thermal energy, so that the stimulable phosphor is The radiation energy (radiation image information) accumulated through absorption is converted into fluorescence and stimulated to emit light.
There is a method of photoelectrically converting this stimulated luminescent light to obtain an image signal.

Specifically, for example, U.S. Pat. It is shown. This method uses a radiation image conversion panel in which a stimulable phosphor layer (stimulable layer) is formed on a support, and radiation transmitted through the object is applied to the stimulable phosphor layer of this conversion panel. , accumulates radiation energy corresponding to the radiation transparency of each part of the subject to form a latent image,
Thereafter, by scanning this photostimulation layer with photostimulation excitation light, the accumulated radiation energy is emitted and converted into light, and this optical signal is photoelectrically converted to obtain a radiation image signal.

The radiographic image signals obtained in this way can be used as they are, or after being subjected to image processing, such as silver halide film, CR
In most cases, the image is output to a T or the like for visualization, or it is digitized for image processing by a computer.

In addition, the digitized radiation image signal is stored in an image storage device such as a semiconductor storage device, a magnetic storage device, an optical disk storage device, or a magneto-optical storage device, and then extracted from these image storage devices as necessary. printer, CR
In some cases, the data may be output to T or the like for visualization.

<Invention or Problem to be Solved> By the way, in the above-mentioned device for reading radiation image information stored and recorded in a stimulable phosphor, a plurality of radiation image conversion panels are selectively set and each When reading radiation images accumulated on a radiation image conversion panel, the stimulable phosphor layer of the radiation image conversion panel often has uneven sensitivity due to uneven coating or scratches during production. As this is unavoidable, it may not be possible to accurately reproduce a radiographic image due to the sensitivity unevenness of each radiographic image conversion panel used, which impairs the quality and quantitative nature of the radiographic image.

In other words, if the radiation image conversion panel has uneven sensitivity, shadows unrelated to the transmitted dose of the subject may appear in the reproduced image, worsening the reproducibility of the radiation image (diagnosis in medical applications). It had become.

If there are multiple radiation image conversion panels that can be selectively set in a radiation image reading device, each of them has different characteristics of sensitivity unevenness, so the radiation image can be changed in response to the multiple types of sensitivity unevenness patterns. It was difficult to reproduce accurately.

In addition to the uneven sensitivity of each radiation image conversion panel, X-ray generators also have uneven doses due to the heel effect (dose unevenness). When radiographic images are stored and recorded in two separate radiographs, and the radiographic images taken at each are read by a single radiographic image reading device, each X-ray generating device has a different pattern of radiation unevenness, so the reading device cannot detect such unevenness in the radiation dose. However, in this case as well, the reproducibility of radiographic images was impaired due to the unevenness of the dose caused by the X-ray generator.

If such unevenness exists, the correspondence relationship between the X-ray dose and the signal value will shift, and the quantitative nature of the signal value with respect to the transmitted X-ray dose will be lost, causing inconveniences in bone fracture measurement.

The present invention has been made in view of the above-mentioned problems, and even if there is unevenness in the sensitivity of a radiation image conversion panel or unevenness in radiation generation in a radiation generating device, it is possible to prevent the reproducibility of radiographic images from being impaired due to such unevenness. The purpose is to provide an image reading device.

<Means for solving the problem> Therefore, the radiation image reading device according to the present invention has the following features:
It is configured as shown in the figure.

That is, the radiation image reading device according to the present invention uses excitation light to scan a radiation image conversion panel that stores and records radiation image information by absorbing radiation from a radiation generating device that has passed through a subject into a stimulable phosphor. By this, the radiation image information stored and recorded in the radiation image conversion panel is made to undergo stimulated luminescence, and the obtained stimulated luminescence light is read out photoelectrically. As shown in FIG. A radiation image information correction means is provided for correcting the read radiation image information based on the corresponding image unevenness information stored in the image unevenness information storage means.

<Operation> According to such a configuration, when there is uneven radiation generation in the radiation generating device or uneven sensitivity in each radiation image conversion panel, information on these image unevenness or radiation used in combination with the radiation image reading device can be used. It is stored in advance for each generation device and each radiation image conversion panel. and,
After photoelectrically reading out the image information stored in the radiation image conversion panel, the radiation generating device or the radiation image conversion panel used to obtain the current radiation image information among the previously stored image unevenness information is read out. Since the radiation image information is corrected based on the information of the corresponding image unevenness, it becomes possible to compensate for deterioration in the reproducibility of the radiation image information due to the radiation generation unevenness and sensitivity unevenness.

<Example> The present invention will be explained in detail below.

FIG. 2 showing one embodiment shows a radiographic image information recording/reading system including a radiographic image reading device 1 according to the present invention and an X-ray imaging device 2 using X-rays as radiation. An example in which the present invention is applied to imaging is shown, and this embodiment assumes a system in which a plurality of X-ray imaging devices 2 and one radiation image reading device 1 are combined.

In the X-ray imaging device 2, an X-ray generator (radiation generator) 3 irradiates X-rays toward a subject 4 (such as a human leg). On the side facing the X-ray generator 3 with the subject 4 in between, there is a photostimulable phosphor plate 1- (radiation image conversion panel).
5 is provided, and this stimulable phosphor plate 5 is
Energy according to the radiation transmittance distribution of the subject 4 with respect to the radiation dose irradiated by the radiation generator 3 is accumulated and recorded in the photostimulable layer, and a latent image of the subject 4 is formed there.

The stimulable phosphor plate 5 has a stimulable layer on a support,
The stimulable layer is provided by vapor phase deposition of a stimulable phosphor or coating of a stimulable phosphor paint, and the stimulable layer is shielded or covered with a protective member to prevent adverse effects and damage from the environment. As the stimulable phosphor material, for example, Japanese Patent Application Laid-Open No. 1982-72091 or Japanese Patent Application Laid-open No. 59-72
Materials such as those disclosed in Japanese Patent No. 75200 may be used.

On the other hand, the stimulable phosphor plate 5 on which the radiation image information of the subject has been accumulated and recorded as described above is set in the radiation image reading device 1, and the accumulated and recorded radiation image information is read out photoelectrically. For example, the stimulable phosphor plates 5 are sequentially automatically transported from each of the plurality of X-ray imaging devices 2, set on the radiation image reading device IH, and read one by one. . Here, it is assumed that a plurality of stimulable phosphor plates 5 are provided and are automatically transported between the radiation image reading device 1 and each X-ray imaging device 2 in turn.

In the radiation image reading device 1, a stimulated excitation light source (gas laser, solid-state laser, semiconductor laser, etc.) 6 generates an excitation light beam whose emission intensity is controlled, and the excitation light beam is used to store radiation image information of the subject. The recorded stimulable phosphor plate 5 is scanned, and the radiation energy (latent image) accumulated in the stimulable phosphor plate 5 is emitted as fluorescence (stimulated luminescence).

The photoelectric conversion device 7 receives the fluorescence (stimulated luminescence) emitted by scanning the stimulable phosphor plate 5 with an excitation light beam through a filter 8 that allows only the fluorescence to pass, and converts the incident light into The radiation image information for each pixel is obtained by photoelectrically converting each pixel into a current signal corresponding to the current signal.

The radiation image information photoelectrically read by the photoelectric conversion device 7 is sent to the radiation image processing device 9, which converts the radiation image information obtained by photoelectric conversion into A/
The digital radiographic image information is converted into digital radiographic image information by a D converter, and the digital radiographic image information is subjected to various image processing (gradation processing, frequency processing, etc.) to form a form suitable for diagnosis, and then transferred to the radiographic image reproducing device 1o. Output.

The radiation image reproduction device 10 is a monitor such as a printer or a CRT', and inputs digital radiation image information processed by the radiation image processing device 9, and visualizes the photographed radiation image as a hard copy or a reproduction screen.

Note that a storage device (filing system) such as a semiconductor storage device may be provided together with the radiation image reproduction device 10 or in place of the radiation image reproduction device 10.

By the way, the radiation image processing device 9 has a function of correcting image unevenness unrelated to the transmitted dose of the subject before image processing such as gradation processing, and in this embodiment, the radiation image The processing device 9 also serves as radiation image information correction means.

The image unevenness is caused by variations in the amount of radiation irradiated to the subject within the image due to unevenness in the amount of X-rays generated by the X-ray generating device 3 of each This is because the energy accumulated for the same radiation dose varies depending on the location due to sensitivity unevenness in the plate 5.

In order to correct radiographic image information regarding such image unevenness, this embodiment includes the following configuration.

That is, for the stimulable phosphor plate 5, sensitivity unevenness is detected by irradiating the same dose of radiation to the entire light-receiving surface of the stimulable phosphor plate 5 in advance (for example, before shipping) and measuring the accumulated radiation energy. Then, correction data for correcting the radiation image information for each pixel read by the photoelectric conversion device 7 is obtained for each stimulable phosphor plate 5 based on the sensitivity unevenness.

On the other hand, the characteristics of unevenness in the amount of X-rays generated by the X-ray generating device 3 of the X-ray imaging device 2 are detected in advance for each of the X-ray generating devices 3 used, and data for correcting such unevenness in the dose is also collected. The pixel unit read by the photoelectric conversion device 7 is determined in correspondence with each X-ray generating device 3.

1. For example, data for correcting the sensitivity unevenness of each stimulable phosphor plate 5 is stored on a magnetic tape on the outside of the imaging area (frame of the cassette) for each stimulable phosphor plate 5. 21 is provided as shown in FIG. 3, and correction data for sensitivity unevenness for each stimulable phosphor plate 5 is stored on the magnetic tape 21 corresponding to the image unevenness information storage means.

Data for correcting unevenness in the amount of X-rays generated by each X-ray generating device 3 is stored in advance in a nonvolatile memory (image unevenness information storage means) built into the radiation image processing device 9. .

Furthermore, when the X-ray imaging device 2 takes an image, an identification number (ID number) indicating the X-ray generating device 3 used for the imaging is recorded on the magnetic tape 21 of the stimulable phosphor plate 5 by a magnetic recording/reading device. 22, and the radiation image reading device l reads the stimulable phosphor plate 5.
When photoelectrically reading the radiographic image stored in the magnetic tape 21, the magnetic reading device 23 reads out the correction data for the sensitivity unevenness recorded on the magnetic tape 21 and the identification number of the X-ray generator 3. Data for correcting uneven radiation generation of the device 3 is obtained by searching for data corresponding to the identification number of the X-ray generating device 3 read out from among the correction data stored in the radiation image processing device 9 in advance. Finally, data for correcting the sensitivity unevenness of the stimulable phosphor plate 5 and data for correcting the unevenness of the generated dose in the X-ray generator 3 are obtained.

The radiation image processing device 9 corrects the pixel-by-pixel radiation image data read out from the stimulable phosphor plate 5 based on these correction data based on two types of correction data corresponding to each pixel. , corrects image unevenness due to sensitivity unevenness and dose unevenness.

The stimulable phosphor plate 5 and the X-ray generator 3 used in combination with the radiation image information reading device 1 in this way
In a system in which there is a limitation, no matter which stimulable phosphor plate 5 or which X-ray generator 3 is used, corrections corresponding to each sensitivity unevenness and dose unevenness can be applied. Moreover, it is possible to prevent the accuracy of radiographic images from being impaired due to dose unevenness, and especially in medical systems, diagnostic performance is improved.

Here, data for correcting the sensitivity unevenness of each stimulable phosphor plate 5 is stored in advance in a non-volatile memory (image unevenness information storage means) built in the radiation image processing device 9. It may be stored in correspondence with the identification number (ID number) of the stimulable phosphor plate 5.

In this case, the magnetic tape 2 of the stimulable phosphor plate 5
1, only the identification signal of the stimulable phosphor plate 5 is written in advance, and the identification signal of the X-ray imaging apparatus 2 is written together with the identification signal of the plate 5 at the time of imaging. .

The radiation image reading device I- then reads the identification signal of the stimulable phosphor plate 5 and the identification signal of the X-ray generator 3 written on the magnetic tape of the stimulable phosphor plate 5 into the magnetic reading device 23. The stimulable phosphor plate 5 and the stimulable phosphor plate 5 read out the radiation image from among the sensitivity unevenness correction data and dose unevenness correction data stored in advance based on these identification signals. The correction data corresponding to the X-ray generator 3 used when the radiation image information was stored and recorded is searched and obtained, and the read radiation image information is corrected pixel by pixel based on these correction data. You can also do it.

The state of image unevenness correction control in the radiation image processing device 9 of the radiation image reading device 1 shown above is shown in the flowchart of FIG.

In the flowchart of FIG. 4, if the radiation image processing device 9 stores the sensitivity unevenness correction data of each of the stimulable phosphor plates 5 in advance, first, from the stimulable phosphor plate 5, Plate 5 identification number (I
D number) is read, and the sensitivity unevenness correction data corresponding to the next 82 lever read identification number is searched.

On the other hand, if the sensitivity unevenness correction data of the stimulable phosphor plate 5 is directly stored, the S
3, the correction data may be read, and in this case, the identification number of the stimulable phosphor plate 5 is not required.

In addition, regarding the data for correcting the dose unevenness of the X-ray generator 3, the identification number (ID number) of the X-ray generator 3 used at the time of imaging is written on the stimulable phosphor plate 5. , this is first read in S4.

Then, in the next step 85, the dose unevenness correction data corresponding to the identification number taken in S4 is searched from among the dose unevenness correction data stored corresponding to each of the X-ray generators 3 used. .

In this way, when the correction data for each pixel for correcting the sensitivity unevenness and the dose unevenness is obtained, in S6, the radiation image information for each pixel read by photoelectric conversion of stimulated luminescence is corrected. By correcting each pixel based on the data, sensitivity unevenness of the stimulable phosphor plate 5 and
It is possible to obtain a radiographic image with accurate reproducibility that is not affected by dose unevenness of the radiation generator 3.

In addition, when the identification number of the stimulable phosphor plate 5 is read by the radiation image reading device 1 side, the magnetic tape 21
Instead, a barcode may be displayed on the fluorescent plate 5.

In the above embodiment, the stimulable phosphor plate 5 and the X-ray generator 3 used for imaging are identified through the magnetic tape 21 provided on the stimulable phosphor plate 5. 2. As shown in Figure 2, the radiographic image reading device 1 and a plurality of combined X-ray imaging devices 2 are connected online, and the identification number of the X-ray generating device 3 and the X-ray generating device 3 are used to take images. A set of imaging information including the identification number of the stimulable phosphor plate 5 may be sent from the X-ray imaging device 2 to the radiation image reading device l.

In this case, each of the stimulable phosphor plates 5 is arranged so that its identification signal can be read as described above, and when the X-ray imaging device 2 takes an image, the magnetic recording/reading device 22
The identification number of the stimulable phosphor plate 5 used for imaging is read, and the identification number of the stimulable phosphor plate 5 is read along with the identification number of the X-ray generator 3 to the radiation image processing device 9 of the radiation image reading device 1. Send directly to online.

On the other hand, in the radiation image processing device 9, correction data for correcting sensitivity unevenness for each stimulable phosphor plate 5 is stored in advance in correspondence with the identification number of the plate 5 (along with X Data for correcting dose unevenness of the X-ray generator 3 is stored in correspondence with the identification number of the X-ray generator 3.

The radiation image processing device 9 stores imaging information consisting of the identification signals of the stimulable phosphor plate 5 and the X-ray generator 3, and reads the identification number of the set stimulable phosphor plate 5. The X-ray generating device 3 used to photograph the stimulable phosphor plate 5 is recognized, and the corresponding correction data for sensitivity unevenness and dose unevenness is stored in advance in correspondence with the identification number. search the data,
The read radiation image information is corrected based on the correction data.

The flowchart in FIG. 5 shows how the image unevenness correction control is performed when such an online system is used.

Here, the Sll stores input data sent via online from the X-ray imaging apparatus 2 for each imaging. The input data includes the identification number of the X-ray generator 3;
The radiation image information and the identification number of the stimulable phosphor plate 5 stored and recorded using the X-ray generator 3 are combined into one set.

In this way, the combination information of the X-ray generator 3 used for imaging and the stimulable phosphor plate 5 taken using this is stored, and the radiation image reading device 1 stores the stimulable phosphor When the stimulable phosphor plate 5 is set, S12 reads the identification number of the stimulable phosphor plate 5,
Based on the online information, the identification number of the X-ray generator 3 used when photographing the set stimulable phosphor plate 5 is recognized.

This enables the identification of the set stimulable phosphor plate 5 and the X-ray generator 3 used when photographing the plate 5.
(X-ray imaging device 2) can be identified, so the next step is S14.
In step S15, the correction data for the sensitivity unevenness corresponding to the identification signal of the stimulable phosphor plate 5 is searched and obtained.
Based on the identification signal of the radiation generator 2, correction data for dose unevenness is searched and obtained.

Then, in S16, the radiation image information read from the stimulable phosphor plate 5 is corrected based on the correction data for correcting the sensitivity unevenness and dose unevenness obtained in S14 and S15, respectively.

Here, the system configuration is not limited to the system configuration shown in FIG. 2, but as shown in FIG. The system may be configured such that the reading section is transported in the order of the erasing section. In the system shown in FIG. 6, the order of the stimulable phosphor plates 5 does not change, so there is no need to check the identification number of the stimulable phosphor plates 5 every time.
It is preferable to use the correction data sequentially in synchronization with the transport of the stimulable phosphor plate 5.

In this embodiment, both the sensitivity unevenness of each stimulable phosphor plate 5 and the radiation dose unevenness of each X-ray imaging device 2 are corrected, or only one of the unevenness characteristics is corrected. You can do it like this.

<Effects of the Invention> As explained above, according to the radiation image reading device according to the present invention, the radiation generation device used to accumulate and store radiation image information in the radiation image conversion panel may have an uneven generated dose, or Even if there is sensitivity unevenness in the radiation image conversion panel, this can be corrected for each X-ray generator or radiation image conversion panel, so that the accuracy of the radiation image information read due to the unevenness can be improved. It has the effect of preventing sexual damage.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the configuration of the present invention, Fig. 2 is a system block diagram showing an embodiment of the invention, and Fig. 3 is a block diagram showing the configuration of the present invention.
FIGS. 4 and 5 are a plan view showing a magnetic tape provided on the illustrated photostimulable phosphor plate (stimulable phosphor), and FIGS. FIG. 6 is a system configuration diagram showing another embodiment of the present invention. 1... Radiographic image reading device 2... X-ray imaging device 3... X-ray generating device 4... Subject 5...
- Stimulable phosphor plate (stimulable phosphor) 6... Stimulable excitation light source 7... Photoelectric conversion device 9... Radiation image processing device 10... Radiation image reproducing device 21.
...Magnetic tape 22...Magnetic recording/reading device
23...Magnetic reader

Claims (1)

[Scope of Claims] A radiation image is created by scanning a radiation image conversion panel with excitation light that stores and records radiation image information by absorbing radiation from a radiation generating device that has passed through the subject into a stimulable phosphor. In a radiation image reading device that causes radiation image information stored and recorded in a conversion panel to undergo stimulated emission and photoelectrically reads the obtained stimulated emission light, the radiation generation unevenness of each radiation generating device and the radiation image conversion panel an image unevenness information storage means that stores in advance image unevenness information that is at least one of sensitivity unevenness for each image; A radiation image reading device comprising: radiation image information correction means for correcting based on unevenness information.