X-ray image producing system

Claim 2

An X-ray image producing system comprising means (11) for producing a beam of X-rays to irradiate an object (12) to be examined, characterized by: means (13) for producing an X-ray shadow image of said object (12) caused by said X-rays that have passed through said object (12); means (14) for converting said X-ray image to a corresponding video signal; means (26; 26L, 26M) for storing the level of said video signal in each of the picture elements which constitute at least one frame; and means (25) for comparing in each of said picture elements the level of said video signal stored in said storing means (26; 26L, 26M) and the level of a succeeding vid.ao signal from said converting means (14) which forms a frame succeeding the frame formed by said stored video signal and causing that one of said video signals whose level satisfies a predetermined condition in magnitude relative to the other to be stored in each of the memory sections of said storing means (26; 26L, 26M) corresponding to said picture elements in place of the data previously recorded therein.

Claim 3

The system of claim 1, wherein said X-ray shadow image producing means (13) comprises an X-ray image intensifier.

Claim 4

The system of claim 1, wherein said converting means (14) comprises a TV camera.

Claim 5

The system of claim 1, further including an A/D converter (23) for digitizing said video signal to be applied to said comparing means (25).

Claim 6

The system of claim 1, further including a TV monitor (16) for displaying the image formed by said video signal from said comparing means (25).

Claim 7

An X-ray image producing system comprising means (11) for producing a beam of X-rays to irradiate an object (12) to be examined, characterized by means (13) for producing an X-ray shadow image of said object (12) caused by said X-rays that have passed through said object (12); means (13, 14) for converting said X-ray image to a corresponding analog video signal; means (23) for digitizing said analog video signal; means (25, 26M) for forming a mask image by the peak value of said digital video signal attained during a predetermined period of time in each of the picture elements of said X-ray image produced before injection of contrast material into said object, and storing said mask image; means (25, 26L) for forming a live image by the peak value of said digital video signal attained during a predetermined period of time in each of the picture elements of said X-ray image produced after injection of contrast material into said object; means (40)for subtracting the digital video signals of said mask image from the digital video signals of said live image; means (27) for converting the digital video signals resulting from said subtraction to a corresponding analog video signal ; and means (16) for displaying said converted analog video signal as a subtraction image.

Claim 8

The system of claim 6, wherein said live image forming means (25, 26L) operates so as to produce a new live image at predetermined time intervals.

Claim 9

The system of claim 5, wherein said peak value of said digital video signal is the highest level of said signal attained during said predetermined period of time.

Claim 10

The system of claim 5, wherein said peak value of said digital video signal is the lowest level of said signal attained during said predetermined period of time.