Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Reexamination Certificate
2001-08-28
2004-05-18
Bennett, Henry (Department: 3742)
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
C600S407000, C600S476000, C600S473000
Reexamination Certificate
active
06738659
ABSTRACT:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
None
FIELD OF THE INVENTION
This invention is in the field of non-intrusively analyzing variations or changes in the different scattering mediums within a non-homogeneous body, by the use of collimated light pulse with a pre-determined pulse duration to illuminate the mediums and by detection of the varying scattering effects on the light produced by the variations in the mediums scattering characteristics.
BACKGROUND OF THE INVENTION
There exist many systems using collimated light from a laser source to illuminate a subject and then by analyzing the light as affected by subject, to determine one or several properties or characteristics of the subject. For example, as shown in U.S. Pat. No. 5,995,866, a short pulse of laser radiation is directed at a subject, which may be tissues, liquids, gases, or solid particles in a suspension, and light reflected or scattered from the subject is scanned by an electro-optical imaging means to generate image signals. Light from the subject causing variable fluorescence or spectral radiation, is detected as varying signals which are processed to detect cancerous cells, to quantize the cells as to number, shape or distribution, and to the stage of development.
U.S. Pat. No. 6,205,353 uses a group of sources of light at different wavelengths and detectors to generate a plurality of time resolved intensity data of back-scattered light from a highly scattered turbid medium and a reconstruction algorithm to reconstruct an image of the medium.
U.S. Pat. No. 5,949,077 shows how cancerous tissue within healthy tissue may be illuminated with collimated light from a laser source so the portion of the light transmitted though the cancerous tissue is captured as a shadow due to the varying absorption and scattering properties of the cancerous tissue relative to the healthy tissue. In the disclosed system, a light wavelength is chosen so an image is formed from the luminescent light from the subject and the light scattered by the scattering medium.
U.S. Pat. No. 5,813,988 uses a laser light source to illuminate a highly scattering turbid medium with a pulse of light. Light from the medium is received by a plurality of intersecting source/detecting sets in combination with time resolving equipment to produce a number of time-resolved intensity curves for the diffusive component of the light emerging from the medium over a relatively long period of time. Each of curves is processed according to an inverse reconstruction algorithm to form an image of the subject.
U.S. Pat. No. 5,140,463 discloses a system for improving the signal to noise ratio of an image signal produced by directing collimated light to an image hidden within a highly scattering semi opaque disordered medium by using space gated imaging or time gated imaging.
U.S. Pat. No. 5,799,656 produces an image of a subject located in or behind a turbid media, such as for example, in the cancer screening of breasts. It utilizes a special property of calcification in breast tissues that are suggestive of cancers and which can be discovered using optical imaging, with time and space gating of the light emerging from the illuminated medium.
U.S. Pat. No. 5,735,276 is similar to U.S. Pat. No. 5,995,866 in its use of collimated light and computer analysis of reflected and fluorescent light from the illuminated subject.
In addition to the patented systems described above, other methods and systems have attempted to use light in different diagnostic methodologies because of its low cost and its non-intrusive and non-ionizing radiation effects. While short pulse lasers were used, the focus of these systems was on analysis of the effect of the subject or probed material on the long term or diffusive component of emerging light or steady state light transmitted through the illuminated material or on the effect of the subject or probed material on the light altered by the transmittance characteristics of the subject material. A disadvantage of these systems is the derived transmittance signal lacks a direct precise correlation between the property of the light illuminating the subject scattering and absorbing medium, for example a tumor, with different transmittance characteristics relative to its surrounding normal tissue, and the different effects or the varying effects on the radiated light produced by the related varying characteristics of the tumor and normal tissue, requiring a complex inverse analysis algorithm to reconstruct the Image.
In the case of scattered or reflected light, relative to the incident light, the temporal profile of the different reflectance signals produced by the different effects of materials with varying scattering characteristics such as a tumor inclusion, and the surrounding medium such as normal tissue, on the light radiation, can be correlated with the spatial distribution of the inclusion. However, there is no capability for processing the reflected signal received from scattering mediums and comprised substantially of the ballistic light photons, traversing the shortest path and carrying the most information, about the scattering mediums, for example a tumor within healthy tissue, with the varying reflectance characteristics of the mediums.
While short pulse width lasers have been used in an attempt to detect enclosed or materials surrounded by partially opaque or turbid mediums, such as a tumor within healthy tissue, the short pulse width laser has not been used in a way that optimizes the recovery of information from the directly reflected signal and provides a detectable signal capable of producing more accurate and precise information at small material sizes, such as the initial growth stages of a cancerous tumor in healthy tissue.
SUMMARY OF THE INVENTION
This invention overcomes the disadvantages of prior art systems that use radiation, such as collimated light from a laser to illuminate a non-homogeneous body, comprising materials with varying light reflectance or transmission or scattering, characteristics, relative to each of the other materials, for producing data indicative of the size, location or image, of the materials enclosed or hidden by the scattering turbid medium of another of the non-homogeneous body's materials. This invention overcomes the prior art systems' disadvantages by illuminating the materials with a radiation pulse having a temporal pulse width minimized, relative to a combined factor t
p
* related to the materials absorption coefficient and speed of propagation for the radiation.
Accordingly, it is an object of this invention, to detect the presence of at least one subject material or subject body or probed body located within or hidden or enclosed by another enclosing material or hiding material, and where the materials are of varying or different light scattering or reflective characteristics so the variations produced by the varying scattering mediums of the respective materials on the radiation, may be detected, analyzed or processed to produce at least one indicator comprising data or displays of the location or size or image, or other measurable indicia of the materials.
It is another object of this invention, to increase the accuracy and precision of the of the reflected signals in detecting an enclosed subject material, enclosed or hidden from the source of radiation, by an enclosing material or layer of material, between the subject material and the source of radiation, by selecting a temporal pulse width t
p
so the combined factor, t
p
* as described below, of the light pulse width t
p
, the extinction coefficient &kgr; for the materials comprised by the materials in a non-homogeneous body, and the propagation speed c of the radiated light through the materials, is selected to minimize combined factor t
p
* or to a value no larger than about 1.
It is another object of this invention to employ a data acquisition system to receive and process perspective related reflected radiation from a non-homogeneous body and the materials within, to construct a two or thr
Bennett Henry
Dahbour Fadi H.
Rosenblatt Joel I.
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