Method for forming energy subtraction images

A method for forming an energy subtraction image comprising the steps of:

• i) after two kinds of radiation images of an object are formed with two kinds of radiation having different energy levels, the object being constituted of a plurality of tissues exhibiting different levels of radiation absorptivity with respect to the two kinds of radiation having different energy levels,
• irradiating said two kinds of radiation images with image detection signals and detecting first and second original image signals based on said image detection signals and representing the two kinds of said radiation images,
• ii) generating a superposition image signal by carrying out a weighted addition expressed as
• S=(N2.sup.2 /N1.sup.2 +N2.sup.2)).times.SO1+(N1.sup.2 /N1.sup.2 +N2.sup.2)).times.SO2
• wherein SO1 represents said first original image signal, N1 represents noise contained in said first original image signal, SO2 represents said second original image signal, and N2 represents noise contained in said second original image signal,
• iii) carrying out a first process for generating a first image signal, which represents a first image primarily composed of patterns of first tissues of said object, by subtracting said first original image signal and said second original image signal from each other,
• iv) thereafter carrying out a second process, which comprises the steps of:
• a) generating a first smoothed image signal by smoothing said first image signal, said first smoothed image signal representing a first smoothed image in which noise components of said first image have been reduced, and
• b) generating a second image signal by subtracting said superposition image signal and said first smoothed image signal from each other, said second image signal representing a second image primarily composed of patterns of second tissues of said object, and
• v) thereafter carrying out a third process, which comprises the steps of:
• a) generating a second smoothed image signal by smoothing said second image signal, said second smoothed image signal representing a second smoothed image in which noise components of said second image have been reduced, and
• b) generating a new first image signal by subtracting said superposition image signal and said second smoothed image signal from each other, said new first image signal representing a new first image primarily composed of the patterns of said first tissues of said object.

A superposition processing method for radiation images, comprising the steps of:

• irradiating two kinds of radiation images of a single object, each present on a medium, with image detection signals and detecting, based on said image detection signals, first and second image signals, each of which comprising a series of image signal components and which represent corresponding picture elements in said radiation images;
• and
• adding the image signal components of the first and second image signals to each other in accordance with the following equation:
• S=(N2.sup.2 /N1.sup.2 +N2.sup.2)).times.S1+(N1.sup.2 /N1.sup.2 +N2.sup.2)).times.S2
• wherein S1 represents the first image signal, N1 represents noise contained in the first image signal, S2 represents the second image signal, N2 represents noise contained in the second image signal, and S represents the addition signal.

A superposition processing apparatus for radiation images comprising:

• means for irradiating two kinds of radiation images of a single object, each present on a medium, with image detection signals and detecting, based on said image detection signals first and second image signals, each of which is made up of a series of image signal components and which represent corresponding picture elements in said radiation images;
• and
• addition means for adding the image signal components of the first and second image signals to each other in accordance with the following equation:
• S=(N2.sup.2 /N1.sup.2 +N2.sup.2)).times.S1+(N1.sup.2 /N1.sup.2 +N2.sup.2)).times.S2
• wherein S1 represents the first image signal, N1 represents noise contained in the first image signal, S2 represents the second image signal, N2 represents noise contained in the second image signal, and S represents the addition signal.

A superposition processing method for radiation images, comprising the steps of:

• irradiating two kinds of radiation images of a single object, each present on a medium, with image detection signals and detecting, based on said image detection signals, first and second image signals, each of which comprising a series of image signal components and which represent corresponding picture elements in said radiation images;
• and
• adding the image signal components of the first and second image signals to each other in accordance with the following equation:
• S=(Sk2/(Sk1+Sk2)).times.S1+(Sk1/(Sk1+Sk2)).times.S2
• wherein S1 represents the first image signal, Sk1 represents a sensitivity of the first image signal, S2 represents the second image signal, Sk2 represents a sensitivity of the second image signal, and S represents the addition signal.

A superposition processing apparatus for radiation images comprising:

• means for irradiating two kinds of radiation images of a single object, each present on a medium, with image detection signals and detecting, based on said image detection signals first and second image signals, each of which is made up of a series of image signal components and which represent corresponding picture elements in said radiation images;
• and
• addition means for adding the image signal components of the first and second image signals to each other in accordance with the following equation:
• S=(Sk2/(Sk1+Sk2)).times.S1+(Sk1/(Sk1+Sk2)).times.S2
• wherein S1 represents the first image signal, Sk1 represents a sensitivity of the first image signal, S2 represents the second image signal, Sk2 represents a sensitivity of the second image signal, and S represents the addition signal.

A superposition processing method for radiation images, comprising the steps of:

• i) irradiating two kinds of radiation images of a single object, each present on a medium, with image detection signals and detecting, based on said image detection signals, first and second image signals, each of which comprising a series of image signal components and which represent corresponding picture elements in said radiation images;
• ii) calculating a sensitivity Sk1 of each of the image signal components of the first image signal and a sensitivity Sk2 of each of the image signal components of the second image signal on the basis of the first image signal S1 and the second image signal S2;
• and
• iii) adding the image signal components of the first image signal and the second image signal in accordance with the following equation to obtain an addition signal S:
• S=(Sk2/(Sk1+Sk2)).times.S1+(Sk1/(Sk1+Sk2)).times.S2.

A superposition processing apparatus for radiation images comprising:

• means for irradiating two kinds of radiation images of a single object, each present on a medium, with image detection signals and detecting, based on said image detection signals, first and second image signals, each of which comprising a series of image signal components and which represent corresponding picture elements in said radiation images;
• and
• means for generating an addition signal based on the image signal components of the first and second image signals, comprising:
• i) an operation device for calculating a sensitivity Sk1 of each of the image signal components of the first image signal and a sensitivity Sk2 of each of the image signal components of the second image signal on the basis of the first image signal S1 and the second image signal S2;
• and
• ii) an addition device for adding the image signal components of the first image signal and the second image signal in accordance with the following equation to obtain an addition signal S:
• S=(Sk2/(Sk1+Sk2)).times.S1+(Sk1/(Sk1+Sk2)).times.S2.

A superposition processing method for radiation images, comprising the steps of:

• i) irradiating two kinds of radiation images of a single object, each present on a medium, with image detection signals and detecting, based on said image detection signals, first and second image signals, each of which comprising a series of image signal components and which represent corresponding picture elements in said radiation images;
• ii) generating an unsharp signal of the first image signal S1 and an unsharp signal of the second image signal S2;
• iii) calculating a sensitivity Sk1 of each of the image signal components of the first image signal and a sensitivity Sk2 of each of the image signal components of the second image signal on the basis of said unsharp signal of the first image signal S1 and said unsharp signal of the second image signal S2;
• and
• iv) adding the image signal components of the first image signal and the second image signal in accordance with the following equation to obtain an addition signal S:
• S=(Sk2/(Sk1+Sk2)).times.S1+(Sk1/(Sk1+Sk2)).times.S2.

A superposition processing apparatus for radiation images comprising:

• means for irradiating two kinds of radiation images of a single object, each present on a medium, with signals image detection and detecting, based on said image detection signals, first and second image signals, each of which comprising a series of image signal components and which represent corresponding picture elements in said radiation images;
• and
• means for generating an addition signal based on the image signal components of the first and second image signals, comprising:
• i) an operation device for generating an unsharp signal of the first image signal S1 and an unsharp signal of the second image signal S2, and calculating a sensitivity Sk1 of each of the image signal components of the first image signal and a sensitivity Sk2 of each of the image signal components of the second image signal on the basis of said unsharp signal of the first image signal S1 and said unsharp signal of the second image signal S2;
• and
• ii) an addition device for adding the image signal components of the first image signal and the second image signal in accordance with the following equation to obtain an addition signal S:
• S=(Sk2/(Sk1+Sk2)).times.S1+(Sk1/(Sk1+Sk2)).times.S2.