the amplitude and phase of several harmonics within a range of frequencies creates a signature of the breast growths allowing differentiation of benign and malignant masses . our invention is novel in that it differentiates normal from abnormal tissue based on observing secondary effects of changes in dielectric properties due to increased numbers of cells based on phase and amplitude of multiple levels of harmonics without the necessity to measure absolute capacitance and resistance values . the invention allows differentiation of benign masses ( e . g ., tumor or infections ) versus malignant masses versus other cellular changes . our approach is not impacted by patient - to - patient differences . other impedance - related approaches ( e . g ., those referenced above from mirabel medical systems , biofield , and davies ) depend on measuring absolute capacitive and absolute resistive properties to compute the cole - cole function shape . measuring absolute values is difficult and inherently error prone , especially since they will vary from patient to patient . to analyze measurements by searching for simultaneous interactions between multiple frequencies , the obvious choice is to use fast fourier transform or discrete fourier transform . however there other transforms that may give very specific and different advantages . chirp - z transform has an advantage of having the ability to focus analysis on specific band of frequencies by performing spectra zooming . the range of data points does not have to be equal to 2 n and in its zoomed form it can be continuously moved to mark time information of the analyzed data . czt ⁡ ( x ⁡ [ n ] ) = ∑ n = 0 n - 1 ⁢ x ⁡ [ n ] · z k - n wavelet transform or discrete wavelet transform has an ability to resolve time and frequencies within the uncertainty principle . cwt x ψ ⁡ ( τ , s ) = 1  s  ⁢ ∫ x ⁡ ( t ) · ψ * ( t - τ s ) ⁢ ⅆ t fft / dft transforms show interactions between frequencies and the same interactions will be shown when using chirp - z or wavelet transform . the additional information these last two transforms bring , while testing tissue , could be used to further mark the signature of these cells for differentiation . an embodiment of a suitable device is shown in the block diagram of fig1 , which illustrates the block diagram of the invention for breast - mass detection . after the unit powers up through the use of user interface 100 , the microprocessor 110 will load the characteristics of the desired square wave to the generator 120 . if another wave type were used ( e . g ., sine or saw tooth ), generator 120 would generate that wave type . as commanded by the medical professional through the input interface 100 , the microprocessor 110 will start coherent sampling by synchronizing the waveform generation 120 and waveform capture 150 . output stage 130 assures proper voltage levels and their rising and falling edges . the output stage 130 also distributes the signal to multiple electrodes as shown in fig1 . microprocessor 110 controls the main frequency and triggers the current capture 150 . the biological tissue 140 is the breast under examination . the sampled current 150 is digitized by analog to digital converter ( adc ) 160 . a fast fourier transform ( fft ) is computed by microprocessor 110 on 2 n samples received from adc 160 . for practical considerations , the n should be equal or greater than 8 . typically it would be 12 , but with microprocessor advances this can be increased for better accuracy . the resulting fft data with its magnitude and phase are compared by the microprocessor 110 with the identifying references stored in it . the references may include markers identifying benign or malignant tumors including their relative position to a probes being tested . all the conclusions of testing by the microprocessor 110 are sent to the display 100 to inform the medical professional . the circuit requires coherent source and sampling conditions to achieve the spectral resolution needed to precisely identify changes in amplitudes and phases caused by masses , including growing cancer cells . coherent sampling is superior over any type of data windowing or interpolation . a wide spectral band is used from around 20 khz to several mhz with odd harmonics . the non - linearities in the tissue will contribute to generation of even harmonics at much smaller amplitude . our invention can be used in the ranges of 10 khz to 1 mhz , or from 1 mhz to approximately 100 mhz , and from 100 mhz to 10 ghz . in one embodiment , the square wave main frequency 200 in fig2 is set to 10 . 74219 khz . this satisfies the coherency condition of 11 cycles , 4096 samples and 250 ns sampling . it places the 93 rd 210 harmonic at 999 . 0234 khz . this setting takes into computation 48 harmonics . research papers have indicated 100 khz to 1 mhz to be affected by growing tumor cells [ 4 ] [ 5 ]. the square wave rising and falling edges were set to 250 ns giving odd harmonic content . all harmonics in the band of the source square wave , as shown with their magnitude in fig2 and the phase in fig3 , are used in the computation . the results of magnitude and phase changes 300 in fig3 are compared with the set of the reference amplitudes and phases as they identify cancer cells [ 2 ] [ 6 ] [ 7 ] [ 8 ]. alternatively , a set of reference amplitudes and phases as they identify masses of benign cells can be used . fig4 shows an example of breast - tissue current with its magnitude response to the square - wave stimulus and fig5 with its phase response . the model of a tumor tissue includes a non - linear capacitor . the harmonic level 400 in fig4 is shifted to larger value . the phase plot 500 in fig5 has changed shape . fig6 and 7 respectively show examples of breast - tissue current in magnitude 600 in fig6 and phase responses to the square - wave stimulus for malignant breast tissue . fig7 compares healthy tissue response with tumor tissue response 700 . the phase and amplitude changes across multiple frequencies differentiate the tissue into healthy cells , benign mass , and malignant tumor . the amount of phase shift at particular frequencies creates a marker to be identified during clinical studies . having in excess of 40 harmonics , the cell signature makes the differentiation very visible . some of the scientific publications show analysis of dielectric properties of tumor cell in the frequency range up to 10 ghz . a modified saw tooth waveform 800 in fig8 with coherent ratio between its period 810 and sampling interval would cover this range . the plateau 820 in the saw tooth could be made variable to tune in into the response of specific tumor cells . the magnitude of fast fourier transform is shown on fig9 . the waveform shows both even and odd harmonics 900 . the phase response of the saw tooth waveform shown in fig1 exhibits small variations in the bandwidth of interest 1000 . the waveform sources 1100 are distributed around the breast 1150 at constant separation angles as shown in fig1 . the nipple is used to connect the detector 1110 . the connection can be made via a cap or other surface connection or via an inserted probe . generating waveforms and collecting data are done by stand - alone device 1120 . the resulting data are transferred to a computer 1130 for visual and mathematical analysis . the receiving electrode 1110 in fig1 may be one covering the nipple , or for increased localization capability may be an electrode made of insulated wire with a bare conducting tip inserted into one of the ( typically on the order of nine ) milk ducts . the localization is in three dimensions . for differentiated signatures , this approaches permits greater localization . in another embodiment the source and receiving electrodes are incorporated in a brassiere . this electrode configuration can be effectively employed for screening where a mass is not palpable or the situation where a mass is palpable . the ecg / ekg pads are distributed in the area where breast attaches to the chest wall . the ecg / ekg pads can be replaced with 30 gauge needles to achieve a higher degree of accuracy . the system is not limited to the use of a square wave . a sine wave can be used with the same coherent setting for multiple frequencies covering similar or the same harmonics . there could be one sine wave source with a non - linear gain element creating harmonics without need to step the frequencies . analyzing magnitude and phase for over 40 harmonics in frequency span from 10 khz to 1 mhz will be a substantial source for the signature differentiating dielectric properties of healthy tissues versus tumor tissue . many publications show cole - cole charts with significant changes when tumor cell start to grow in this frequency span . in other embodiments , the number of source electrodes is varied . the larger the number of source electrodes , the higher the resolution of localization . for example having eight source electrodes arranged around the perimeter of the breast will double the localization capability since the area of the breast will be divided into eight regions as opposed to quadrants . where in some applications of the device , one only wants to do screening to know whether a lesion is likely present or not , in others being able to localize would be important . this may occur , for example , if one is tracking changes in the lesion . tracking can be done by taking a base measurement , instilling a therapeutic agent in one or a plurality of milk ducts , and assessing the progress of treatment via follow - up measurements . an alternative source electrode configuration is shown in fig1 for breast 1250 . this has a single source probe electrode 1205 with receiving electrode 1210 . generating waveforms and collecting data is done by stand - alone device 1220 . the resulting data is transferred to a computer 1230 for visual and mathematical analysis . the configuration of fig1 shows the configuration of fig1 in conjunction with breast 1350 containing an example lump 1315 characterized by employing source electrode ( probe ) 1305 and receiving electrode 1310 . generating waveforms and collecting data are done by stand - alone device 1320 . the resulting data are transferred to a computer 1330 for visual and mathematical analysis . in this configuration , three - dimensional reconstruction is not required because the impedance characteristics would be determined for a single palpable mass over which the electrode is placed . in this mode , the device is used for evaluation of a given mass as opposed to screening for a non - palpable breast mass . fig1 demonstrates a variation of configurations of fig1 and 13 in conjunction with breast 1450 in which source probe electrode 1405 is moved around the base of the breast 1450 with the single receiving electrode 1410 . generating waveforms and collecting data are done by stand - alone device 1420 . the resulting data are transferred to a computer 1430 for visual and mathematical analysis . in this configuration , movement of the single - source probe electrode 1405 around the base of breast 1450 in a roughly circular trajectory allows data collection of the type in fig1 in which a three - dimensional reconstruction and thus 3 - d localization of a breast mass can be accomplished . the position of the single - source probe and its movement can be shown on the computer screen so the program knows for which location data is collected . thus this configuration can be used for screening in which a breast mass can be detected and characterized through its signature , whether than mass was palpable or not . feedback to the user as to results may take multiple forms . in one embodiment , the presence an abnormality is a non - visual feedback . this is supplied by an auditory or vibratory cue . tone patterns can provide either a binary or relative magnitude , including level of probability . in another embodiment , the presence of an abnormality is indicated by a simple visual cue such as an led display , either binary or relative magnitude , including level of probability . in another embodiment , the presence of an abnormality is indicated by an intermediate visual display presenting text or graphical results , including level of probability and 3 - d location . in still another embodiment , the presence of an abnormality is indicate by a complex visual display presenting raw data and processed graphical information , including level of probability . the invention can be used as a screening device for initial , non - radiation involving , low - cost exam where , if the result is positive , a higher functionality version of the invention is used ( for example , one with full display capabilities ) and / or other techniques such as mammography , magnetic resonance imaging , positron emission tomography , and ultrasound . for screening purposes it is usually important to adjust the detection level so that the results are biased to having false positives and avoiding false negatives since the false positive tests can be followed up more intensively , or , in some cases , by repetition of the initial type of test . one can adjust relationships among true positives and negatives and false positives and negatives . specificity and sensitivity can be adjusted as well . an important approach to the testing of such devices is the ability of comparing the healthy tissue in one breast to a potential lesion in the other breast in the same patient . fig1 a and b show the test configurations for melanoma . fig1 a illustrates the test instrument applied to potential melanomas on the face with spring - action electrodes 1500 being applied with only the tips conductive and handle with wires 1510 . fig1 b shows the electrode pair used to confine skin lesions as illustrated in fig1 a . spring - action electrodes 1530 have exposed semicircular electrodes 1550 at the tips ( one of which is the source electrode and the other the receiving electrode and which one is which is arbitrary ). spring - action electrodes 1530 are covered by insulation 1540 and are connected to the electronic instrumentation by wires 1560 and become embedded in cable 1570 . in one embodiment , the semicircular electrodes are between 7 to 12 millimeters in diameter and separated up to 15 mm . the electrodes are insulated so they can touch each other if pushed together without shorting . fig1 shows the oral cavity with such structures as the upper lip 1600 , lower lip 1620 , tongue 1610 , tonsil 1630 , and uvula 1640 . the oral cavity is accessible and lesions often superficial . the impedance - measurement interface consists of a tweezers - style electrode pair 1650 insulated to the electrode active areas 1660 with source and receiving electrodes ( which one is which does not matter ) connected to cable 1670 . the impedance - measurement interface can be applied any of the mentioned structures but any other included structures such as the mucosa of the cheeks , the gingiva , or the oral pharynx . if an area such as the tongue is sensitive , the area being measured can first have an anesthetic topically applied . fig1 shows the testing configuration for the lung . measurements can be made on the anterior of the patient as shown in fig1 a or the posterior surface as shown in fig1 b . in fig1 a , source electrode 1700 can be preferentially located above the shoulder just posterior to clavicle or at position 1710 on the lateral surface of the side of the thorax being examined , in this case the left side of the patient . the receiving electrodes 1730 are located laterally to sternum 1720 located in the midline . any if the electrodes are to be placed in the intercostal spaces or other areas ( e . g ., posterior to the clavicle ) to minimize the interference of underlying cartilage or bone . fig1 b covers impedance measurements on the posterior surface of the patient . in fig1 b , source electrode 1750 can be preferentially located above the shoulder just posterior to clavicle or at position 1760 on the lateral surface of the side of the thorax being examined , in this case the left side of the patient . the receiving electrodes 1780 are located laterally to spine 1770 located in the midline fig1 shows the test configuration for the liver . in fig1 , liver 1800 is contained within rib cage 1810 anchored by sternum 1820 with source electrode 1840 placed laterally on the side of the patient ( or with alternative position at the position of the receiving electrode 1850 ), typically also posteriorly , with receiving electrodes ( suggested to be ) the source electrode 1850 ( open - square symbols ) placed over the surface of the skin overlying liver 1800 . as was true for the lung above , the source and receiving electrodes are placed in the intercostal spaces or below the rib cage if the liver protrudes inferiorly to the rib cage to avoid interference by cartilage or bone . fig1 shows the test configuration for the colon or rectum . inside abdomen , 1900 is rectum 1910 and colon 1920 . specially outfitted colonoscope 1930 is threaded through the anus through rectum 1910 and the body of colon 1930 to the lesion of be assessed at location 1940 at which a semicircular electrode configuration of the type shown in fig1 b with one of the semicircular electrodes being the source electrode and the other the receiving electrode . the semicircular electrodes can be applied to lesions within the rectum as well as those within the colon . fig2 shows the test configuration for the cervix in the context of a cross section of the pelvis . the organs shown are the vagina 2000 , the uterus 2010 , rectum 2020 , bladder 2030 , and cervix 2040 . to analyze cervix 2040 , instrumented speculum 2050 is introduced through vagina 2000 and semicircular electrodes 2060 are applied to lesions on cervix 2040 with the electrodes connected to the impedance analyzer through wires 2070 . the same instrumentation can be applied to masses in the vaginal cavity other than the cervix . the vaginal cavity is accessible and lesions often superficial . fig2 shows test configurations for the prostate with fig2 a and fig2 b illustrating alternative electrode configurations . organs shown in the vertical section of fig2 a are rectum 2100 , bladder 2105 , testis 2110 , penis 2115 , urethra 2120 , and prostate gland 2125 . the source electrode 2130 provides one side of the impedance analysis circuitry and receiving electrode 2135 . alternatively , the receiving electrode could be located at a different position 2140 . source electrode 2130 and one or both of receiving electrodes 2135 and 2140 are connected with the impedance analysis instrument ( not shown ) by wires 2145 . fig2 b shows a vertical section through the male pelvic region demonstrating an alternative mechanism for doing the impedance measurement and analysis . the organs illustrated are the rectum 2160 , prostate 2165 , testis 2170 , penis 2175 , and urethra 2180 . in this embodiment , the source electrode 2185 is placed in urethra 2180 and the receiving electrode 2190 are both connected to the impedance analysis instrument ( not shown ) by wires 2195 . fig2 shows the test configuration for performing impedance analyses of biopsied tissue samples . the source electrode is a plate 2200 on which the tissue sample is placed and is connected to the impedance analysis instrument ( not shown ) by wire 2210 . plate 2200 is only conductive on the top surface ; the sides and bottom are insulated . the tissue sample has its bottom resting on source electrode plate 1900 and the top of the sample has a receiving electrode 2220 , typically a disk 7 to 15 mm in diameter pressed into it . receiving electrode 2220 is secured to insulated handle 2230 . wire 2240 connects receiving electrode 2220 to the impedance analysis instrument ( not shown ). the surfaces of the plate 2200 or receiving electrode 2220 may be flat , curved , or an arbitrary shape . while the approach described is applied to breast tissue , the same techniques with the same parameters can be applied for detecting abnormalities in other tissues , including , but not limited to , for example , lung and prostate tissue , using suitable source and receiving electrodes . it is noted that any embodiment described herein for exemplary purposes is , of course , subject to variations . because variations and different embodiments may be made within the scope of the inventive concept ( s ) herein taught , it is to be understood that the details herein are to be interpreted as illustrative and not in a limiting sense .
a device is described for measuring electrical characteristics of biological tissues with plurality of electrodes and a processor controlling the stimulation and measurement in order to detect the presence of abnormal tissue masses in organs . examples of suitable organs are the breast , skin , oral cavity , lung , liver , colon , rectum , cervix , and prostate and determine probability of tumors containing malignant cancer cells being present in tissue . the approach can also be applied to biopsied tissue samples . the device has the capability of providing the location of the abnormality . the method for measuring electrical characteristics includes placing electrodes and applying a voltage waveform in conjunction with a current detector . a mathematical analysis method is then applied to the collected data , which computes spectrum of frequencies and correlates magnitudes and phases with given algebraic conditions to determine mass presence and type .