Method for automatic detection of glandular tissue

• US 6,556,655 B1
• Filed: 11/29/1999
• Issued: 04/29/2003
• Est. Priority Date: 11/27/1998
• Status: Expired due to Term

• Current Assignee: GE Medical Systems Norway AS (General Electric Company)
• Original Assignee: GE Medical Systems Norway AS (General Electric Company)
• Inventors: Bossaert, Jean, Chichereau, Claire
• Primary Examiner(s): Kim, Robert H.
• Assistant Examiner(s): Ho, Allen C.
• Application Number:
  US09/450,918
• Time in Patent Office: 1,247 Days
• Field of Search: 378/37, 378/62, 378/108
• US Class Current: 378/108
• CPC Class Codes: A61B 6/502 for diagnosis of breast, i.e. mammography
• CPC Class Codes: G01N 2223/419 computed tomograph
• CPC Class Codes: G01N 23/046 using tomography, e.g. computed tomography [CT]
• CPC Class Codes: H05G 1/22 with single pulses
• CPC Class Codes: H05G 1/46 Combined control of different quantities, e.g. exposure time as well as voltage or current

Abstract

The method consists of subjecting the organ to pre-exposure with a low dose of rays, creating in the field of the pre-exposure image a multi-cellular image in which each cell represents the mean signal level of a predetermined number of pixels of the detector, selecting from the columns the cell of minimum signal level most distant from a reference point, establishing about this cell a band parallel to the reference point and selecting from the band the cell having the absolute minimum signal level. The parameters of exposure may then be set from this absolute minimum

Claims

1. A method for automatic detection of a tissue of predetermined nature in an organ part examined by digital X-ray radiography, comprising the steps of:

a) establishing parameters of pre-exposure from a table of automatic optimization of parameters, a given theoretical composition and an estimated radiologic thickness of the organ part examined and for a low but sufficient dose of X-rays to obtain a pre-exposure image of sufficient quality for the differentiation of tissues of the organ part examined;

b) establishing a minimum dose level and of a maximum dose level from a predetermined mechanical thickness of the organ part examined and conversion of these dose levels into a minimum threshold signal level and a maximum signal threshold level, readable by a detector;

c) pre-exposing the organ part examined to obtain a pre-exposure image;

d) creation in a zone of interest of the field of the pre-exposure image of a multi-cellular image of columns in which each cell indexed with regard to a reference point represents the logarithmic mean of the signal levels between the minimum threshold level and the maximum threshold level of a predetermined number of pixels of the detector;

e) determination in each column of the position, with respect to the reference point, of the cell having the minimum signal level to obtain a set of retained cells;

f) selection from the set of retained cells of the one whose position is most distant from the reference point;

g) determination of a band, parallel to the reference point, including the retained cell, the width of which is proportional to the distance of the cell selected with respect to the reference point and search in this band for the cell having the absolute minimum signal level; and

h) using the absolute minimum signal level to establish the parameters of exposure of the organ part examined by X-rays.

2. The method according to claim 1, wherein after step (d) and before steps (e) to (h), the method additionally includes:

(1) elimination of all cells having a signal level below the minimum threshold signal level established in step (a);

(2) establishing the minimum position and a maximum position in depth, determined from the reference point, of a device which may perhaps be present for compression of the organ part examined;

(3) establishing a threshold value;

(4) establishing a line situated between the minimum and maximum positions in depth of any possible compression device and parallel to the reference point;

(5) comparing the threshold value of the variation in signal level between two consecutive cells along the line, and for all the cells on the line;

(6) recording two positions, if they exist, along the line for which variations in signal level have passed from a value greater than the threshold value to a value lower than the inverse of the threshold value;

(7) verifying the distance between the two recorded positions, when they exist, is greater than a predetermined value, satisfaction of the conditions of steps (6) and (7) determining the presence of the compression device; and

(8) carrying out of steps (e) to (h) in a zone delimited by the two positions recorded in step (6) and the minimum and maximum positions in depth established in step (2).

3. The method according to claim 1, wherein the organ part examined is a breast.

4. The method according to claim 2, wherein the organ part examined is a breast.

5. The method according to claim 3, wherein the zone of interest consists of the glandular tissue of the breast.

6. The method according to claim 4, wherein the zone of interest consists of the glandular tissue of the breast.

7. The method according to claim 3, wherein the reference point consists of the chest wall.

8. The method according to claim 4, wherein the reference point consists of the chest wall.