Apparatus for determining an image position, and method for adjusting read-out conditions and/or image processing conditions for a radiation image

• US 5,668,889 A
• Filed: 06/07/1995
• Issued: 09/16/1997
• Est. Priority Date: 04/19/1990
• Status: Expired due to Term

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fuji Photo Film Co Limited (Fujifilm Holdings Corporation)
• Inventors: Hara, Shoji
• Primary Examiner(s): Couso, Jose L.
• Application Number:
  US08/478,404
• Time in Patent Office: 832 Days
• Field of Search: 382/128, 382/130, 382/131, 382/132, 382/292, 382/294, 378/37, 378/99, 364/413.13, 364/413.26, 358/111, 358/167, 358/524
• US Class Current: 382/132
• CPC Class Codes: G06T 2207/10116 X-ray image
• CPC Class Codes: G06T 2207/30068 Mammography; Breast
• CPC Class Codes: G06T 7/12 Edge-based segmentation
• CPC Class Codes: G06T 7/174 involving the use of two or more images
• CPC Class Codes: G06T 7/73 using feature-based methods

Abstract

An apparatus for determining an image position obtains an image signal representing the whole image, which has been recorded approximately over the whole area of a recording medium, by carrying out an image read-out operation from approximately the whole area of the recording medium, at part of which an object image has been recorded. The position of the object image on the recording medium is determined on the basis of the image signal. A certainty operation device is provided to calculate the degrees of certainty, which indicate step-wise the levels of probability that the object image will be present in partial regions on said recording medium. The degree of certainty is calculated for each of the partial regions on the recording medium, in which partial regions the object image is expected as being recorded. A position determining device is provided to determine the position of the object image on the recording medium on the basis of a plurality of the degrees of certainty, which have been calculated for the respective partial regions on the recording medium.

Claims

1. A method for adjusting read-out conditions and/or image processing conditions for a radiation image, wherein a first image signal made up of a series of image signal components representing a radiation image, in which an object image is embedded at part, is obtained by exposing a stimulable phosphor sheet, on which the radiation image has been stored, to stimulating rays, which cause the stimulable phosphor sheet to emit light in proportion to the amount of energy stored thereon during its exposure to radiation, the emitted light being detected,

a second image signal representing the radiation image is thereafter obtained by again exposing the stimulable phosphor sheet to stimulating rays, the light emitted by the stimulable phosphor sheet being detected, and

read-out conditions, under which the second image signal is to be obtained, and/or image processing conditions, under which the second image signal having been obtained is to be image processed, are adjusted on the basis of the first image signal,

the method for adjusting read-out conditions and/or image processing conditions for a radiation image comprising the steps of:

i) detecting a change in said first image signal at an edge of said object image,

ii) thereby finding a plurality of points, which are spaced apart from each other and located at positions in the vicinity of the edge of said object image, said positions being slightly spaced apart from said object image,

iii) creating a probability density function of the image signal components of said first image signal corresponding to a region, which is surrounded by lines connecting the plurality of the thus found points and which approximately corresponds to said object image, and

iv) adjusting the read-out conditions and/or the image processing conditions on the basis of the results of an analysis of said probability density function.

2. A method for adjusting image processing conditions for a radiation image, wherein image processing conditions, under which an image signal is to be image processed, are adjusted on the basis of the image signal made up of a series of image signal components representing a radiation image, in which an object image is embedded at part,

the method for adjusting image processing conditions for a radiation image comprising the steps of:

i) detecting a change in said image signal at an edge of said object image,

ii) thereby finding a plurality of points, which are spaced apart from each other and located at positions in the vicinity of the edge of said object image, said positions being slightly spaced apart from said object image,

iii) creating a probability density function of the image signal components of said image signal corresponding to a region, which is surrounded by lines connecting the plurality of the thus found points and which approximately corresponds to said object image, and

iv) adjusting the image processing conditions on the basis of the results of an analysis of said probability density function.

3. A method for adjusting read-out conditions and/or image processing conditions for a mamma radiation image including a chest wall pattern, wherein a first image signal made up of a series of image signal components representing respective picture elements in a radiation image of an object is obtained by exposing a stimulable phosphor sheet, on which the radiation image has been stored, to stimulating rays, which cause the stimulable phosphor sheet to emit light in proportion to the amount of energy stored thereon during its exposure to radiation, the emitted light being detected, the radiation image being composed of:

a) an object image region constituted of a chest wall pattern, which extends along an edge of the stimulable phosphor sheet, and a mamma pattern projecting in an approximately semicircular shape from the chest wall pattern toward an edge of the stimulable phosphor sheet facing the edge, along which the chest wall pattern extends, and

b) a background region, which is adjacent to the object image region, and upon which the radiation impinged directly without passing through the object,

a second image signal representing the radiation image is thereafter obtained by again exposing the stimulable phosphor sheet to stimulating rays, the light emitted by the stimulable phosphor sheet being detected, and

read-out conditions, under which the second image signal is to be obtained, and/or image processing conditions, under which the second image signal having been obtained is to be image processed, are adjusted on the basis of the first image signal,

the method for adjusting read-out conditions and/or image processing conditions for a mamma radiation image including a chest wall pattern comprising the steps of;

i) detecting a change in said first image signal,

ii) thereby finding a plurality of boundary points between said object image region and said background region,

iii) finding the center of gravity on said stimulable phosphor sheet on the basis of the image signal components of said first image signal, which represent a plurality of picture elements located along a line connecting each said boundary point and said edge of said stimulable phosphor sheet, along which edge said chest wall pattern extends,

iv) finding a picture element spaced apart from the position, at which said center of gravity is located, in a direction heading away from each said boundary point by a distance equal to a value obtained by multiplying the distance between the position, at which said center of gravity is located, and said boundary point by a predetermined factor, and

v) adjusting the read-out conditions and/or the image processing conditions on the basis of the image signal components of said first image signal corresponding to the region surrounded by the plurality of said boundary points and a plurality of the picture elements, which have thus been found.

4. A method for adjusting image processing conditions for a mamma radiation image including a chest wall pattern, wherein an image signal made up of a series of image signal components representing respective picture elements in a radiation image of an object is obtained by photoelectrically reading out the radiation image from a recording medium, on which the radiation image has been recorded, the radiation image being composed of:

a) an object image region constituted of a chest wall pattern, which extends along an edge of the recording medium, and a mamma pattern projecting in an approximately semicircular shape from the chest wall pattern toward an edge of the recording medium facing the edge, along which the chest wall pattern extends, and

b) a background region, which is adjacent to the object image region, and upon which the radiation impinged directly without passing through the object, and

image processing conditions, under which the image signal is to be image processed, are adjusted on the basis of the image signal,

the method for adjusting image processing conditions for a mamma radiation image including a chest wall pattern comprising the steps of;

i) detecting a change in said image signal,

ii) thereby finding a plurality of boundary points between said object image region and said background region,

iii) finding the center of gravity on said recording medium on the basis of the image signal components of said image signal, which represent a plurality of picture elements located along a line connecting each said boundary point and said edge of said recording medium, along which edge said chest wall pattern extends,

iv) finding a picture element spaced apart from the position, at which said center of gravity is located, in a direction heading away from each said boundary point by a distance equal to a value obtained by multiplying the distance between the position, at which said center of gravity is located, and said boundary point by a predetermined factor, and

v) adjusting the image processing conditions on the basis of the image signal components of said image signal corresponding to the region surrounded by the plurality of said boundary points and a plurality of the picture elements, which have thus been found.