UWB Microwave Imaging System with A Novel Calibration Approach For Breast Cancer Detection

Abstract

An apparatus and method for imaging a tissue. The method includes transmitting a first microwave frequency signal to and receiving a first total signal from the tissue at a first position. A second microwave frequency signal is transmitted to and a second total signal received from the tissue at a second position. The first total signal is calibrated with respect to the second total signal and an image is constructed from the calibrated signal.

1 . A method of imaging a tissue, the method comprising:
 transmitting a first microwave signal in a frequency range of 2 GHz to 8 GHz to the tissue at a first position;   receiving a first total signal reflected from the tissue at the first position;   transmitting a second microwave signal in a frequency range of 2 GHz to 8 GHz to the tissue at a second position;   receiving a second total signal reflected from the tissue at the second position;   calibrating the first total signal with the respect to the second total signal by subtracting the second total signal from the first total signal resulting in a calibrated signal; and   constructing an image of the tissue from the calibrated signal.   
     
     
         2 . The method of  claim 1 , wherein the second position is radially-spaced away from the first position by an angle that ranges from about 0.5 degrees to about 5 degrees. 
     
     
         3 . The method of  claim 1 , wherein the second position is linearly-spaced away from the first position by a distance that ranges from about 1 mm to about 20 mm. 
     
     
         4 . The method of  claim 1 , wherein the tissue comprises a glandular soft tissue and includes at least one mass located therein. 
     
     
         5 . The method of  claim 4 , wherein the first and total signals each include a first portion having reflections due to a tissue-air interface, a second portion having reflections due to a transmitter-receiver coupling, a third portion having reflections due to the at least one mass, and a fourth portion having reflections due to multiple scatterings. 
     
     
         6 . The method of  claim 1 , wherein transmitting each of the first and second total signals further comprises:
 generating an alternating signal;   mixing the alternating signal with an oscillating clock signal;   amplifying the mixed signal at a high-gain amplifier; and   transmitting the amplified, mixed signal to a transmitting antenna.   
     
     
         7 . The method of  claim 1 , wherein receiving each of the first and second total signals further comprises:
 amplifying received first and second total signals at a low-noise amplifier;   down-converting the amplified signal into two channels;   mixing the down-converted signal of each of the two channels with an oscillating clock signal; and   converting the mixed signal from each of the two channels to a respective digital signal.   
     
     
         8 . (canceled) 
     
     
         9 . The method of  claim 1 , wherein constructing the image further comprises: applying a delay and sum algorithm to the calibrated signal. 
     
     
         10 . The method of  claim 1 , wherein a first transducer transmits the first microwave frequency signal and receives the first total signal and a second transducer transmits the second microwave frequency signal and receives the second total signal. 
     
     
         11 . The method of  claim 1 , wherein a transducer transmits the first microwave frequency signal and receives the first total signal at the first position and is then moved to the second position for transmitting the second microwave frequency signal and receiving the second total signal. 
     
     
         12 .- 26 . (canceled) 
     
     
         27 . A method of reconstructing an image a tissue from a first microwave signal and second microwave signals, the method comprising:
 receiving the first microwave signal, in a frequency range of 2 GHz to 8 GHz, reflected from the tissue at a first position;   receiving the second microwave signal, in a frequency range of 2 GHz to 8 GHz, reflected from the tissue at a second position;   calibrating the first microwave signal received with the respect to the second microwave signal received by subtracting the second microwave signal received from the first microwave signal received resulting in a calibrated signal; and   constructing an image of the tissue from the calibrated signal.   
     
     
         28 . The method of  claim 1 :
 wherein, the first and second positions are separated by less than 20 mm.