Batteries: thermoelectric and photoelectric – Thermoelectric – Processes
Reexamination Certificate
1999-09-13
2001-01-30
Gorgos, Kathryn (Department: 1741)
Batteries: thermoelectric and photoelectric
Thermoelectric
Processes
C136S213000, C136S233000, C374S179000
Reexamination Certificate
active
06180867
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to thermal sensors and more particularly to thermal sensors for thermography.
2. Description of the Related Art
Conventional breast cancer screening techniques are based on detection and evaluation of tissue mass structure. X-Ray mammography is commonly uses for breast cancer screening. Several drawbacks of X-Ray mammography include: (a) exposure of a population to systematic doses of radiation; (b) reduced effectiveness of X-Ray mammography in the case of dense breasts (a relatively common condition among young women); (c) reluctance of some women to undergo the uncomfortable procedure; and (d) inability of X-Ray mammography to detect early tumors of small size. For detection, the mass must be of a minimum size.
It has been shown that angiogenesis (the recruitment of new blood vessels from existing vessels) is a necessary condition for all solid tumors to grow beyond a diameter of several millimeters (J. Folkman, New England J. of Medicine, 285:1182-1186, 1971; N. Weidner et. al. , New England J of Medicine, 324:1-8,1991). The increased blood vasculature and blood perfusion associated with early tumor growth together with the increased metabolic output of tumors that are growing are hypothesized to lead to higher tumor temperatures than found for surrounding tissues. This hypothesis has been verified in a qualitative manner for tumors that are near the surface of skin in the case of breast cancer. Thus, thermographic sensing with an appropriate technique that is sensitive enough and is free of errors caused by other environmental factors would be useful as a screening method for cancer, particularly for breast cancer.
In applications such as aforementioned U.S. Pat. No. 5,909,004, thermographic sensors are used to measure thermal temperature gradients. To minimize the perturbation of the thermal temperatures being measured, the sensor must have minimal lateral thermal conductivity. In addition, the thermal time constant and mass must be minimized so that rapid reading of the temperatures can be accomplished. In the field of thermography, the surface temperature of the human body is mapped to provide information that is indicative of early tumor growth.
Infrared (IR) cameras or imagers have been used to attempt to measure small temperature gradients. An example of a thermoelectric infrared detector array can be found in Sclar, U.S. Pat. No. 4,558,342. Measurements of temperature distributions in human tissue to detect tumors must map the surface temperature accurately so that any contribution from internal tumors can be properly detected. Infrared sensors (which cannot be in direct contact with skin) can yield unreliable temperature data due in part to effects of ambient air flow on the skin surface and due to variations in skin emissivity and orientation relative to the infrared sensor. Skin emissivity can be a particularly insidious problem in practice and varies due to the presence of a variety of substances on the skin such as oil, water or particulate debris. Variations in emissivity cause apparent changes in temperature as sensed by the infrared camera that mask the underlying true temperature gradients on the skin.
SUMMARY OF THE INVENTION
Thus, there is a need of a noninvasive, harmless method and apparatus for measuring spatial and/or temporal temperature gradients in biological tissue for screening for angiogenesis and metabolic changes associated with very early tumor development and for monitoring changes in tumor size.
It would additionally be desirable to provide improved thermal sensors while minimizing sensor effects on the thermal field being measured.
It would further be desirable to provide improved detection systems that measure other parameters than the emissive characteristics of the surface and also have a reduced need for calibration and tight environment control, to process resulting data digitally to improve the detection sensitivity, and to provide fixturing devices to help stabilize data acquisition and localize signal position.
In one embodiment of the present invention, an array of temperature sensors is interconnected using thin film interconnects and attached to a low thermal conductivity, low thermal mass material to provide a sensor array with reduced lateral thermal conductivity and losses. In contrast to IR imaging techniques which measure IR and infer temperature while taking emissivity into account (temperature T=function of emissivities and detected IR signals), the present invention can be used to provide direct contact voltage measurements that can be converted to corresponding temperature values with less complexity and likelihood of error (T=voltage signal V * constant K).
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Hedengren Kristina Helena Valborg
Kornrumpf William Paul
Miller Mark Lloyd
Opsahl-Ong Beale Hibbs
Uzgiris Egidijus Edward
Agosti Ann M.
Breedlove Jill M.
General Electric Company
Gorgos Kathryn
Parsons Thomas H.
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