32 2 2013 4 Chinese Journal of Biomedical Engineering Vol. 32 No. 2 April 2013 1 1* 2 1 300072 2 300052 Agilent 4294A 100 Hz ~ 100 MHz Cole-Cole 3 ~ 5 1. 6 ~ 3. 3 R α τ f c P < 0. 05 EIT R318 A 0258-8021 2013 02-0178-06 Experimental Study of Dielectric Properties on Human Lung Tissue WANG Jie-Ran 1 WANG Hua-Xiang 1* XU Xiao 2 1 Institute of Electrical Engineering and AutomationTianjin UniversityTianjin 300072China 2 Department of RadiotherapyGeneral Hospital of Tianjin Medical UniversityTianjin 300052China Abstract This study is aim to investigate the differences of dielectric properties between lung cancer tissue and the normal tissue in vitro and establish the dielectric parameter frequency spectrum of human lung tissue which provide the basic theory and reference data for medical research and clinical diagnosis of lung cancer. Two main categories of tissues were considered as specimens the central part of the tumor and the normal tissue around the tumor. After operationspecimens was put into test chamber in which the temperature and humidity were controlled at expected values. Then the measurement of specimens dielectric properties was performed at frequency from 100 Hz to 100 MHz using 4294A impedance analyzer of Agilent Company. Finally the two categories of tissues characteristic parameters were extracted by using the least square curve fitting method based on Cole-Cole model. The relative permittivity of lung cancer tissue was 3 ~ 5 times larger than that of the normal tissue. The conductivity of lung cancer tissue was 1. 6 ~ 3. 3 times larger than that of the normal tissue. Impedance spectroscopy of lung cancer tissue moved apparently to low impedance direction. Among the characteristic parameters R α τandf c the difference of low frequency resistance between the two categories of tissues was statistically significant P < 0. 05. The differences of dielectric properties and low frequency resistance between lung cancer tissue and the normal tissue are significantwhich provide basic data for human lung tissue s dielectric properties research and EIT measurement. Key words dielectric properties impedance spectroscopy lung cancer tissue characteristic parameters doi 10. 3969 / j. issn. 0258-8021. 2012. 02. 08 2012-09-30 2012-12-30 50937005 12JCYBJC19500 08JCYBJC03500 * E-mail hxwang@ tju. edu. cn
2 179 1 1 a R m C m R i C i X R e C e CT R m electrical impedance tomographyeit C i C e 1 b 2 EIT EIT 19 Gabriel 3-5 6-7 8-10 1. a 100 b Fig. 1 Equivalent circuit models of biological Hz ~ 100 MHz tissue. a The original one b The Cole-Cole simplified one 1 11 Z = R + - R 1 1. 1 1 + jωτ τ = R i + R e C m = R e 30 R i R e R = 2 R 30 i + R e Cole 30 min 30 Cole-Cole 12 R 14 0 - R Z = R + 3 1 + ( jωτ) 1 - α 1. 2 ω = 0 R 0 R ω = τ α 0 ~ 1 α = 0 2 f c f c = 1 /2πτ
180 32 Fig. 2 2 Cole-plot of biological tissue 1. 3 4 Fig. 4 Environment platform of the dielectric PC spectrum measurement system Agilent 1. 4. 2 42942A GPIB PC Matlab Labview 5 mm 12 mm C = - 1 /2πfX 4 ε r = Cd / ε 0 S 5 42942A 16092 σ = d / RS 6 3 d S R C X f ε 0 ε 0 = 8. 854 19 10-12 F / m SPSS Kruskal-Wallis 3 30 Fig. 3 Dielectric spectrum measurement Kruskalplatform of human lung tissues Wallis α = 0. 05 t P < 0. 05 4 1. 4. 3 1. 4 1. 4. 1 Cole-Cole x i y i i 2 N N x 0 y 0 r 37 90 % 100 Hz ~ 100 MHz Q x 0 y 0 r = N 槡 x i - x 0 2 + y i - y 0 - r 2 31 8
2 181 a = - 2x 0 b = - 2y 0 c = x 2 0 + y 2 0 - r 2 8 Q a b c = N x 2 i + c 2 9 a b c a = 0 b = 0 c = 0 10 9 ~ 10 a = N 2 x 2 i + c x i = 0 11 b = N 2 x 2 i + c y i = 0 12 c = N 2 x 2 i + c = 0 13 a b c x 0 = - a /2 y 0 = - b /2 r = 1 /2 槡 a 2 + b 2-4c 14 3 ~ 5 1 ~ 100 khz 2. 2 5 b 100 khz 100 Hz ~ 100 MHz 0. 08 ~ 0. 87 S / m 0. 26 ~ 1. 41 S / m 100 Hz ~ 1 khz 1 khz 3. 3 = x + r 2 2 槡 - y 15 R = x - r 2 2 槡 - y 16 α = 2 π arcsin ( y r ) 17 τ = 1 1 / 1 - α 1 - Z i ω i N N ω i ( Z i ω i - R ) 18 ω i 5 a 2 b Fig. 5 Dielectric spectrum properties of lung cancer tissue and the normal tissue. a Relative 14 30 permittivity b Conductivity Kruskal-Wallis 2. 3 P > 0. 05 Cole-Cole 1 khz ~ 10 MHz 2. 1 6 5 a 1 khz ~ 10 MHz 1 khz
182 32 1 ~ 2 1 2 R α τ f c 6 Fig. 6 Cole-plot of lung cancer tissue and 1 the normal tissues Tab. 1 Fitting circle parameters of lung tissue x y r 14 ~ 18 P > 0. 05 t P < 0. 05 716. 37 ± 253. 69 948. 82 ± 370. 55 1106. 31 ± 414. 84 317. 18 ± 71. 36 394. 95 ± 263. 33 473. 67 ± 260. 61 P 0. 005 0. 008 0. 005 Tab. 2 2 Characteristic parameters of lung tissue / Ω R / Ω α τ 10-7 f c / MHz 1280 ± 421 153 ± 69 0. 66 ± 0. 06 5. 70 ± 3. 71 0. 52 ± 0. 42 558 ± 143 76 ± 80 0. 64 ± 0. 08 6. 82 ± 0. 12 1. 04 ± 0. 62 P 0. 002 0. 102 0. 955 0. 831 0. 114 3 R α τ f c 42942A EIT 16092 100 1 Jemal ABray FCenter MMet al. Global cancer statistics J. CA Cancer J Clin201161 269-90. Hz ~ 100 MHz 2. J. 200827 3641-649. 3 Gabriel CGabriel SCorthout E. The dielectric properties of biological tissues I. Literature survey J. Phys Med Biol 199641 2231-2249. 4 Gabriel SLau RWGabriel C. The dielectric properties of biological tissues II. Measurements in the frequency range 10 Hz 3 ~ 5 to 20 GHz J. Phys Med Biol199641 11 2251-2269. 1. 6 ~ 3. 3 5 Gabriel SLau RWGabriel C. The dielectric properties of biological tissues III. Parametric models for the dielectric spectrum of tissues J. Phys Med Biol199641 2271 - EIT 2293. 6. 100 Hz ~ 10 MHz J. 199920 3220-222.
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