JP2842475B2 - Digital X-ray equipment - Google Patents

Description

The present invention relates to an X-ray imaging apparatus for obtaining a video signal of an X-ray transmission image, and more particularly, to a digital X-ray which digitizes a video signal and performs various processes. Related to the device. (B) Conventional technology Conventionally, X-rays are emitted from an X-ray tube toward a subject,
X-rays transmitted through the subject are incident on an image intensifier (II), and a TV camera is coupled to the X-rays II to obtain a video signal of an X-ray transmission image, which is displayed as a fluoroscopic image on a TV monitor or the like. It has been used to aid in medical diagnosis. In a digital X-ray apparatus, this video signal is digitized and recorded, and various processes are performed, or the video signal is converted back to an analog video signal and displayed on a TV monitor or the like. (C) Problems to be Solved by the Invention By the way, in a subject such as a chest having a wide dynamic range, X-ray absorption in a lung field is small, and in a heart, it is very large. Therefore, when low tube voltage imaging is performed on a chest with a wide dynamic range in which the X-ray absorption difference differs greatly, the contrast in the lung field is good, but fine shadows are completely lost in the heart. On the other hand, when high tube voltage imaging is performed, the fine structure of the heart is conversely extracted, but the contrast in the lung field becomes very poor. In the conventional imaging method, the tube voltage is set according to the purpose of diagnosis for the chest where the lung field and the heart overlap in this way,
You have to choose one image and sacrifice the other. In particular, blood vessels, bronchi, and intestines are present in the lungs,
These shadows need to be diagnosed in relation to the heart, and it is required for image interpretation that both the lung and the heart are displayed on a single image without loss of fine structure. An object of the present invention, as exemplified above, is to provide an X-ray digital apparatus capable of obtaining an image having high diagnostic value including fine information over all parts of a subject having a wide dynamic range. (D) Means for Solving the Problems In order to achieve the above object, a digital X-ray apparatus according to the present invention uses an X-ray tube for irradiating an X-ray to a subject and an X-ray image transmitted through the subject. Imaging means for converting to a signal, A / D conversion means for converting the video signal to a digital signal,
X-ray control means for applying a high tube voltage at the time of high tube voltage photographing and a low tube voltage at the time of low tube voltage photographing to the X-ray tube, and a digital video signal for both high and low photographing stored as image data. A coefficient K is applied to data read from the frame memory and one frame memory, and a coefficient 1-K (where K + (1-
K) = 1), and an adder for adding the outputs of both multipliers is provided. (E) Operation The X-ray control means applies a high tube voltage to the X-ray tube during high tube voltage imaging, and applies a low tube voltage to the X-ray tube during low tube voltage imaging. The X-ray image transmitted through the subject at the time of both high and low tube voltage imaging is converted into a video signal by the imaging means, and is converted into a digital video signal by the A / D conversion means. Digital video signals at the time of high / low tube voltage photographing are stored as image data in respective frame memories, and the read data is subjected to respective multiplication means.
, But the other is multiplied by a factor 1-K. The adding means adds the outputs of the two multiplying means, and the added output is converted back to an analog video signal and displayed on a TV monitor or the like as a fluoroscopic image. Therefore, by setting the multiplication coefficient K of the multiplication means, both the high tube voltage photographed image and the low tube voltage photographed image can be made clear, that is, an image containing minute information on all parts of the subject having a wide dynamic range can be obtained. Can be. The multiplying means can change the multiplication coefficient K in a range of K + (1−K) = 1. (F) Embodiment Preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of a main part of the first embodiment. In the figure, an X-ray tube 10 irradiates an X-ray to a subject 11, and the X-ray passing through the subject 11 is incident on an image intensifier (II) 12. An optical image corresponding to the X-ray transmission image is output from the II 12, and the optical image is sent to the TV camera 13 via an optical system (not shown), and the TV camera 13 outputs a video signal representing the X-ray transmission image. can get. The video signal obtained from the TV camera 13 is converted into a digital signal by the A / D converter 1. The converted digital signal is stored as image data in the frame memory 2 at the time of high tube voltage shooting, and is stored as image data in the frame memory 3 at the time of low tube voltage shooting. The image data read from the frame memories 2 and 3 are led to multipliers 4 and 5 capable of varying a multiplication coefficient and multiplied by the coefficients. The outputs of the multipliers 4 and 5 are added by an adder 6. You. The output of the adder 6 is sent to a D / A converter 7 to be converted back to an analog video signal, sent to a TV monitor 8 and displayed. In the embodiment, the multiplier 4 multiplies the coefficient K, and the multiplier 5 multiplies the coefficient 1-K. However, the inverse may be used, and the coefficient K is K + (1-K) = 1. Can be set arbitrarily within the range. Next, the operation of the device configured as described above will be described. Switching the applied voltage of the X-ray tube between the high tube voltage and the low tube voltage
High tube voltage photographing and low tube voltage photographing are performed by one X-ray exposure. Switching of the tube voltage between the high tube voltage imaging and the low tube voltage imaging is controlled by an X-ray control device (not shown). Of the two images obtained by the two X-ray exposures,
The image of the high tube voltage is stored in the frame memory 2 and the image of the low tube voltage is stored in the frame memory 3 as image data. For example, as for the chest radiograph, in the high tube voltage radiographed image, the contrast in the lung field A is reduced as shown in FIG. 2A, but the fine structure is well extracted in the heart B. In the low tube voltage photographed image, as shown in FIG. 2 (b), the heart B is crushed at the entire black level, but the lung field A is crushed.
Then, the fine structure is well extracted. According to this embodiment, both image data read from the frame memories 2 and 3 are multiplied by K and (1−K) by the multipliers 4 and 5 and then added by the adder 6. You. The added output is converted into an analog signal by the D / A converter 7 and displayed on the TV monitor 8. Accordingly, an image obtained by simply adding the two images at a ratio of 1: 1 is displayed as an image uniformly including the fine structures of both parts as shown in FIG. 2 (c). FIGS. 2 (d), (e) and (f) show the level values of FIGS. 2 (a), (b) and (c), respectively. In the embodiment of the present invention, two images are weighted and added, respectively.
The same applies to the above images. (G) Effect According to the digital X-ray apparatus of the present invention, an image having a high diagnostic value can be obtained for a subject having a large dynamic range having a large X-ray absorption difference, including fine shadow information over all parts.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of one embodiment of the present invention, and FIG. 2 is a diagram for explaining the operation. 1: A / D converter, 2, 3: Frame memory 4, 5: Multiplier, 6: Adder 10: X-ray tube, 11: Subject 12, Image intensifier (II) 13: TV camera

Claims (1)

(57) [Claims] An X-ray tube that irradiates an X-ray toward a subject; an imaging unit that receives an X-ray transmitted through the subject and converts the X-ray image into a video signal; and an A / A that converts the video signal into a digital signal.
D conversion means, X-ray control means for applying a high tube voltage at the time of high tube voltage imaging and a low tube voltage at the time of low tube voltage imaging to the X-ray tube, and a digital video signal at the time of high and low tube voltage imaging. Each frame memory to be stored as image data, a coefficient K for the data read from one frame memory, and a coefficient 1- for the data read from the other frame memory.
A digital X-ray apparatus, comprising: multiplying means for multiplying K (where K + (1−K) = 1); and multiplying means for adding outputs of both multiplying means.