Method of and device for localizing a deviant region in a turbid medium

• US 6,718,195 B2
• Filed: 03/28/2001
• Issued: 04/06/2004
• Est. Priority Date: 03/31/2000
• Status: Expired due to Term

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: ʼT Hooft, Gert Wim, Van Der Mark, Martinus Bernardus, Wachters, Arthur Johannes Hubertus
• Primary Examiner(s): Bennett, Henry
• Assistant Examiner(s): DAHBOUR, HENRY
• Application Number:
  US09/819,282
• Publication Number:
  US 20010026848A1
• Time in Patent Office: 1,105 Days
• Field of Search: 600/473, 600/476, 600/407, 600/438, 600/458, 600/410, 600/310, 600/475, 600/477, 356/432, 356/433, 250/573, 250/341.1, 250/339.06, 250/330, 250/338.1, 250/358.1
• US Class Current: 600/473
• CPC Class Codes: A61B 5/0091 for mammography
• CPC Class Codes: A61B 5/1455 using optical sensors, e.g. spectral photometrical oximeters
• CPC Class Codes: A61B 5/4312 Breast evaluation or disorder diagnosis A61B5/0091 takes precedence
• CPC Class Codes: G01N 21/4795 spatially resolved investigating of object in scattering medium in vivo A61B

Abstract

The invention relates to methods of localizing a deviant region in a turbid medium. The invention also relates to devices for carrying out such methods. The methods can possibly be used in optical mammography where a breast of a female body is examined using light. Said methods produce images in which any deviations, for example tumors, can be clearly recognized. This is achieved inter alia by providing markers (10) in an image (9) of the turbid medium.

Claims

1. A method of localizing a deviant region in a turbid medium that is represented by a set of volume elements, which method includes

a first measuring step (1) in which the turbid medium is irradiated by means of light comprising radiation of mainly a first wavelength and in which intensities of a part of the light comprising radiation of mainly the first wavelength that is transported along a plurality of light paths through the turbid medium are measured,

and an imaging step (4) for reconstructing an image (9) of the turbid medium from the measured intensities,

characterized in that

the method also includes at least a second measuring step (2) in which the turbid medium is irradiated by means of light comprising radiation of mainly a second wavelength which is not equal to the first wavelength,

and in which intensities of a part of the light comprising radiation of mainly the second wavelength that is transported along a plurality of light paths through the turbid medium are measured,

and that the imaging step (4) includes the following steps:

a first calculation step (6) in which a value is assigned to at least a first parameter in dependence on the intensities measured for a volume element in the measuring steps, said first parameter representing a property of the turbid medium,

a second calculation step (7) in which a significance value is assigned to the volume element in dependence on the value of at least the first parameter,

a display step (8) for displaying in the image of the turbid medium (9) for a point in the image that corresponds to one of the volume elements, the significance value (10) of the corresponding volume element.

2. A method as claimed in claim 1, characterized in that the method includes a third measuring step (3) in which the turbid medium is irradiated by means of light comprising radiation of mainly a third wavelength that is not equal to the first wavelength or the second wavelength,

and in which intensities of a part of the light comprising radiation of mainly the third wavelength that is transported along a plurality of light paths through the turbid medium are measured,

and that in the first calculation step (6) a value is assigned to a second parameter in dependence on the intensities measured for a volume element in the measuring steps, said second parameter representing a property of the turbid medium that is not the same as that represented by the first parameter,

and that in the second calculation step (7) a significance value is assigned to the volume element in dependence on the value of the first parameter and on the value of the second parameter.

3. A method as claimed in claim 2, characterized in that the first wavelength has a value of between 830 nm and 900 nm, that the second wavelength has a value of between 750 nm and 830 nm, and that the third wavelength has a value of between 655 nm and 750 nm.

4. A method as claimed in claim 3, characterized in that the first parameter represents a quantity of blood in a volume in the turbid medium that corresponds to one of the volume elements,

and that the second parameter represents a deoxygenation ratio of blood in a volume in the turbid medium that corresponds to one of the volume elements.

5. A method as claimed in claim 1, characterized in that the parameters define a parameter space (20), that in the second calculation step (7) the volume elements are assigned a position (23) in the parameter space (20) in dependence on the values assigned to the parameters for the relevant volume element,

and that the significance value assigned to a volume element is determined by the position of the volume element in the parameter space.

6. A method as claimed in claim 5, characterized in that the parameter space (20) is subdivided into at least a first sub-space (24) and a second sub-space, that the volume elements are assigned a first significance value when they occupy a position in the first sub-space,

and that the volume elements are assigned a second significance value when they occupy a position in the second sub-space.

7. A method as claimed in claim 5, characterized in that the significance value is determined at least by the distance between the position (23) assigned to the volume element and a selected position (26) in the parameter space.

8. A method as claimed in claim 7, characterized in that the significance value is determined inter alia by the situation of the position assigned to the volume element relative to the selected position.

10. Computer program comprising a set of instructions for carrying out the method according to claim 1 or 9.

9. A method of localizing a deviant region in a turbid medium that is represented by a set of volume elements, which method includes

a first measuring step (1) in which the turbid medium is irradiated by means of light comprising radiation of mainly a first wavelength,

and in which intensities of a part of the light comprising radiation of mainly the first wavelength that is transported along a plurality of light paths through the turbid medium are measured,

and an imaging step (4) for reconstructing an image of the turbid medium,

characterized in that

the method also includes at least a second measuring step (2) in which the turbid medium is irradiated by means of light comprising radiation of mainly a second wavelength which is not equal to the first wavelength,

and in which intensities of a part of the light comprising radiation of mainly the second wavelength that is transported along a plurality of light paths through the turbid medium are measured,

and that the imaging step (4) includes the following steps:

a first calculation step (6) in which a value is assigned to at least a first parameter in dependence on the intensities measured for a volume element in the measuring steps, said first parameter representing a property of the turbid medium,

a reconstruction step (13) for reconstructing an image (11) of the turbid medium from at least the value assigned to the first parameter for the volume element.

12. A device for imaging a deviant region in a turbid medium which is represented by a set of volume elements, which device includes

means for irradiating the turbid medium by means of light comprising radiation of mainly a first wavelength,

means for measuring intensities of a part of the light comprising radiation of mainly the first wavelength that is transported along a plurality of light paths through the turbid medium, and means for reconstructing an image of the turbid medium from the measured intensities,

characterized in that

the device also includes means for irradiating the turbid medium by means of light comprising radiation of mainly a second wavelength which is not equal to the first wavelength,

and also means for measuring intensities of a part of the light comprising radiation of mainly the second wavelength that is transported along a plurality of light paths through the turbid medium,

and means for assigning, in dependence on the measured intensities for a volume element a value to at least a first parameter which represents a property of the turbid medium,

and means for assigning a significance value to the volume element in dependence on the value of at least the first parameter,

and means for displaying the significance value of the corresponding volume element in the image of the turbid medium for each point in the image that corresponds to one of the volume elements.

11. Record carrier comprising the computer program according to claim 12.

13. A device for imaging a deviant region in a turbid medium which is represented by a set of volume elements, which device includes

means for irradiating the turbid medium by means of light comprising radiation of mainly a first wavelength,

means for measuring intensities of a part of the light comprising radiation of mainly the first wavelength that is transported along a plurality of light paths through the turbid medium,

and means for reconstructing an image of the turbid medium,

characterized in that

the device also includes means for irradiating the turbid medium by means of light comprising radiation of mainly the second wavelength that is not equal to the first wavelength,

means for measuring intensities of a part of the light comprising radiation of mainly the second wavelength that is transported along a plurality of light paths through the turbid medium,

means for assigning, in dependence on the measured intensities for a volume element, a value to at least a first parameter which represents a property of the turbid medium,

and means for reconstructing the image of the turbid medium from at least the value assigned to the first parameter for the volume element.