传递函数在生物组织光传输问题中的应用_英文__cropped

传递函数在生物组织光传输问 题 快递公司问题件快递公司问题件货款处理关于圆的周长面积重点题型关于解方程组的题及答案关于南海问题 中的应用_英文__cropped 激 光 生 物 学 报 第 13 卷第 3 期 Vol . 13 No . 3 J un. 2004 2004 年 6 月ACTA LASER B IOLOGY SINICA ?组织光学? L ight Transport in Biological Tissues : Ξ Transfer Function ’s Introduction and its Appl ications WANG Chun2yong , LAI J ian2cheng , L I Zhen2hua , HE A n2zhi ()Department of Information Physics & Engineering , Nanjing University of Science & Technology , Nanjing 210094 , Jiangsu ,China Abstract : In this paper , the concept of transfer function in biological tissues is introduced , thus light distribution on the plane of certain depth in the biological tissues irradiated by surface light source can be obtained by transfer function theory simply. Combin2 ing Monte Carlo simulation obtaining the impulse response function , we calculate the light distribution on the emitting surface of a2r tificial biological tissue irradiated by different surface light sources. All theoretical calculating results are well matched with those obtained by the CCD2based experimental measurements. Our research verifies that Monte Carlo based transfer function theory is a direct and effective tool in dealing with light distribution and propagation in biological tissues irradiated by complex surface light sources. Key words : light propagation ; light distribution ; transfer function ; Monte Carlo simulation ; tissues optics CL C number : Q632 ; R318. 04 Document code : A () Article ID : 100727146 20040320173205 传递函数在生物组织光传输问题中的应用 王春勇 , 来建成 , 李振华 , 贺安之 ()南京理工大学理学院信息物理与工程系 ,中国江苏 南京 210094 摘 要 :本文将传递函数的概念引入生物组织光传输问题 ,并将传递函数理论用于面光源照射下生物组织内特定 深度层面上光场强度分布的理论计算 。结合 Monte Carlo 模拟获取脉冲相应函数 ,我们 分析 定性数据统计分析pdf销售业绩分析模板建筑结构震害分析销售进度分析表京东商城竞争战略分析 了不同面光源照射下层 状组织样品透射面上的光场强度分布 。理论计算结果与实验测试结果的一致性较好 ,这充分说明了本文建立的基 于 Monte Carlo 模拟的传递函数方法是一种处理面光源照射下生物组织内光场空间的直接而有效的手段 。 关键词 : 光传输 ;光分布 ;传递函数 ;Monte Carlo 模拟 ;组织光学 中图分类号 : Q632 ; R318. 04 文献标识码 : A () 文章编号 : 100727146 20040320173205 1 ,2 ,3( ) PDT, Photo Thermotherapy and Diaphanography . 0 Introduction A large number of papers have been published in the past The investigation of light propagation and distribution decade in which light propagation within turbid biological 2 ,3 in biological tissues is the foundation and prerequisite of media play an important role. Various theoretical ( ) Photodynamic Diagnosis PDD, Photodynamic Therapy treatments , such as Beer’s law , Kubelka2Munk models Ξ Foundation item : The research is sonsored by Youngster Science and Technology Foundation of Jiangsu province under grant ()BQ2000006 Received date : 2004201205 ( )( ) ( )()G u , v = F u , vH u , v 1 and diffusion approximation theory have been applied in + ?+ ? 4 ,5 the research. However , their accuracy is restricted to jux ivy 1 ()( ) ( ) 2 g x , y= G u , ve e d ud v2 certain conditions. Especially , they can not deal with the (π) ?? 2- ?- ? problems where the biological tissue is irradiated by a ( ) ( ) Where , F u , vand H u , vare light source dis2 complex surface source , which in fact has more practical tribution in the frequency domain and transfer function of significance. Though Monte Carlo method can simulate the biological tissue , 5 + ?+ ? light propagation in any cases theoretically, the huge - jux - ivy ( )()( ) F u , v 3 = G u , ve e d ud ycalculating capacity required in the simulation limits its ?? - ?- ? practical applications mostly on the 12D light distribution + ?+ ? - jux - ivy in terms of pencil light irradiating. In this paper , the ( )( ) ()H u , v = G u , ve e d ud y4 ?? - ?- ? concept of transfer function is introduced into the tradi2 ( ) ( ) Where , f x , y and h x , y represent the distri2 tional Monte Carlo method to deal with light propagation bution function of incident light source and the impulse through biological tissues that is regarded as a linear space response function respectively. displacement invariable system. This new model is named ( In our digital calculations , source distribution f x , Monte Carlo based transfer function theory. Typical simu2 ) yis obtained by experimental measurement . The impulse lation results of light distributions on the emitting surface response function is derived by using the Monte Carlo of artificial biological tissues irradiated by different surface method to calculate the light distribution on emitting sur2 light sources are presented in light of the new model . All face of artificial biological tissues irradiated by pencil the simulation results are well matched with those of the light , and the transfer function is obtained by impulse re2 experimental measurements , which shows that the Monte sponse function ’s Fourier transformation. The transfer Carlo based transfer function theory is an effective tool to function on the emitting surface of the artificial biological deal with light distribution and propagation in biological tissue is demonstrated in Fig. 1 . The corresponding opti2 tissues irradiated by complex surface light sources. cal parameters of the artificial biological tissue adopted in Theoretical model 1 the calculation are given in table 1 . In clinical applications of laser diagnosis and treat2 ment , the transverse size of biological tissues is generally much lager than the diameter of the irradiating laser beam. The biological tissue can generally be regarded as a linear space displacement invariable system. A photon () packet of light energypropagating in the tissue will form an energy distribution in the tissue , i . e . , the im2 pulse response function and its Fourier transformation called transfer function , which can characterize the light transport property of the tissue . According to the theory of Linear System , light distribution in certain depth or on 2 Fig. 1 Transfer function on the emitting surface of ar ( ) the transmission plane of the biological tissue , g x , y , tificial biological tissue can be obtained simply by the following calculations : Tab. 1 Optical parameters of the tissue used in this paper Absorption Scattering Index of Anisotropy factor Thickness - 1 - 1 ()()refraction ()()g cm coefficient cm coefficient cm 1 . 37 1 . 0 23 0. 71 0 . 3 No . 3 WANG Chun2yong , et al :Light Transport in Biological Tissues : Transfer Function’s Introduction and its Applications 175 Tab. 2 Optical parameter of the intralipid and ink at 2 Description of experimental system 633nm - 1 2 . 1 The fa brication of the artif icial biological tissue μIntralipid Scattering coefficient= 377cm s - 1 Biological tissues could be regarded as a dual2parts μAbsorption coefficient= 1449cm Ink a system in terms of its optical property. The phantom me2 2 . 2 Experimental setup dium used in our experiment is an aqueous mixture of In2 In our experiment , a 5mW output He2Ne laser is tralipid and black india ink. Intralipid is almost purely served as the laser source and it is expanded and collimat2 scattering , while the ink is an effective pure absorber . ed in parallel beam with diameter 0 . 5cm. Aperture re2 The phantom medium was selected by varying the relative strictores with different shapes are fixed on the front plane concentrations of ink and Intralipid. The optical proper2 of the sample cell to form typical surface light sources. ties of Intralipid are widely investigated in the Tissue Light distributions on emitting surface of artificial biologi2 6 Optics, whose optical parameters at 633nm are listed in cal tissues are recorded by a CCD camera . The experi2 the table 2 . mental setup is illustrated in Fig. 2 . Fig. 2 The experimental setup of light intensity distribution measurement () 1 : He2Ne laser ; 2 :Normalizing lens ; 3 :Aperture stop ; 4 : Aperture restrictores ; 5 : Sample cell 0 . 3cm in depth; ( ) 6 : Ground glass ; 7 : Beam profiler Photon Inc . Model 2350. Fig. 7, Fig. 10 illustrate the influence of the round 3 Typical simulating and experimental results shield to the result of the light distribution on the emitting surface of the tissue . As it is expected , the round shield 3 . 1 L ight distribution on the emitting surface of the whose diameter is 1Π2 of the diameter of the laser beam tissue irra diated by Ga uss bea m induces a sunk in the center of the light distribution on Fig. 3 is the gray image of the incident laser beam the emitting surface of artificial biological tissue in Fig. 8 and Fig. 4 and Fig. 5 are the results of light distribution and Fig. 9 . Reviewing the curves in Fig. 10 , that are the on the emitting surface of the artificial tissue obtained by light distribution over radius on the emitting surface of the the Monte Carlo based transfer function theory and the artificial tissue irradiated by typical Gauss beam blocked CCD based measurement setup respectively. Fig. 6 illus2 with a round shield in the center , one can conclude that trates that Light distribution over radius on the emitting the intensity of light in the center is not equal to zero , surface of the artificial tissue irradiated by typical Gauss which ascribes to the highly scattering characteristics of beam. the tissue . The consistence of the light distribution on the From Fig. 6 , one can see that light distribution on emitting surface obtained by experiment and the simula2 the emitting surface of the artificial tissue obtained by the tion verifies that Monte Carlo based transfer function theo2 Monte Carlo based transfer function theory is well matched ry adopted in this paper is an efficient and exact way of with that obtained by the experimental measurement . dealing with light distribution in biological tissues irradiat2 3 . 2 L ight distribution on the emitting surface of the ed by complex surface sources. tissue irra diated by the Ga uss bea m blocked with a round shield in the center Fig. 3 Gray distribution of light source Fig. 7 Gray distribution of light source Fig. 4 Gray distribution of light on the emitting sur2 2 Fig. 8 Gray distribution of light on the emitting sur face of face of the artificial tissue obtained by the transfer the artificial tissue obtained by the transfer function theory function theory Gray distribution of light on the emitting sur2 2 Gray distribution of light on the emitting surFig. 5 Fig. 9 face of the artificial tissue obtained by CCD based mea2 2 face of the artificial tissue obtained by CCD based measurement setup surement setup Fig. 6 Light distribution over radius on the emitting Fig. 10 Light distribution over radius on the emitting surface of the artificial tissue irradiated by typical gauss surface of the artificial tissue irradiated by typical gauss beam beam blocked with a round shield in the center No . 3 WANG Chun2yong , et al :Light Transport in Biological Tissues : Transfer Function’s Introduction and its Applications 177 References 4 Conclusion KENNEDY J C , POTTIER R H , PROSS D C. Photodynamic 1 therapy with endogenous protoporphyrin J . J Photochem In this paper , a new theoretical model for describing Photobiol B Biol , 1990 , 6 : 1432148. light distribution and propagation in biological tissues is 2 L IU D L , WANG I , ANDERSSON E S , et al . Intra2opera2 developed by introducing the transfer function to charac2 tive laser2induced photodynamic therapy in the treatment of terize the tissue’s light transport property. Light distribu2 experimental hepatic tumours J . Eur J Gastroenterol Hepa 2 tion on the plane of certain depth in the tissue is the prod2 tol , 1995 , 7 :107321080. uct of the distribution of incident light source in frequency 3 VERKRUYSSE W , PICKERING J W , BEEK J F , et al . domain and the tissue’s transfer function. The method is Modelling the effect of wavelength on the pulsed dye laser used to calculate the light distributions on the emitting treatment of port wine stains J . Appl Opt , 1993 , 32 : 393 2 surface of the artificial biological tissue , and the results 398. 4 ISHIMARU A. Wave propragation and scattering in random are well matched with that obtained by experiment . Our media M . New York : Academic , 1978. research illustrate that the Monte Carlo based transfer 5 WANG Li2hong. Monte Carlo modeling of light transport in function not only has the advantages of direct Monte Carlo multi2layered tissuesD . University of Texas M D Anderson method , i . e . , universality , precision , but also has Cancer Center , 1992. unique potential of high calculating efficiency , so it is a 6 FLOCK S T , JACQUES S L , WILSON B C. Optical proper2 preferred theoretical tool to deal with light distribution and ties of intralipid : a phantom medium for light propagation propagation in biological tissues irradiated by complex studiesJ . Lasers in Surgery and Medicine , 1992 , 12 :510 2 surface light sources. 519. 作者简介 王春勇 : 男 ,工程师 。1988 年毕业于长春光学精密机械学院 ,获“电子技术及应用”专业学士学位 ;1997 年在南京理工大学“自动控制原理及应用”专业获硕士学位 。现任南京理工大学理学院信息物理与工 程系教师 ,并在本系“光学工程”专业攻读博士学位 。现主要从事微弱光信号的检测 、信号的处理以及 组织光学等领域的研究工作 。 Biogra phy WANG Chun2yong : was born in 1967. He received his Bachelor’s degree from Changchun University of Science and Technology in 1988 and M. S. degree from Nanjing University of Science and Technology in 1997. He now is working in Department of Information Physics and Engineering in Nanjing University of Science and Technology. His interests are detection of small light signal , information processing and tissues optics.