摘要
人体辐射健康危害取决于辐射能量在人体的沉积分布及后续复杂的生物学过程。依据辐射损伤机制经典学说--靶学说,DNA分子是辐射损伤最重要的靶,辐射能量在其内的沉积特点对辐射生物效应的解释具有重要意义。考虑到细胞是人体的基本功能单元且DNA分子受损后的各种生物学响应均与细胞环境有关,因此,在细胞水平开展辐射剂量学研究对辐射损伤机制的深入了解及其在辐射防护和放射治疗等方面的实用化具有重要意义。
目的:单细胞模型是辐射能量在细胞水平上沉积特点和规律获取的重要平台。本文旨在得到合理可行的单细胞模型建立方法,并据此建立更加接近真实细胞的Monte Carlo计算模型。
材料与方法:采用具有肿瘤细胞代表性的人口腔上皮癌细胞作为研究对象,基于生物学手段和计算机图形技术摸索模型的建立方法,并结合GEANT4蒙特卡罗模拟软件进行辐射照射下细胞内能量沉积规律的获取。
结果:成功建立了单细胞模型,并针对该模型进行了适用性和实用性的测试。在此基础上进行了剂量学计算,结果表明,在综合考虑计算时间和计算精度的情况下对7组数据进行分析,最终将图像分辨率设为0.3-0.4μm范围内,用200个3MeV的α粒子对单细胞模型进行照射,得到细胞核内单个粒子击中细胞的平均比能均值为0.209Gy;细胞质内单个粒子击中细胞的平均比能均值为0.044Gy。
本文得到的计算结果与已公布数据吻合,建立单细胞体素模型的方法切实可行且通用性强;细胞核的密度与细胞形态对模型计算结果有重要影响,建立不同细胞系的细胞库是对于放射生物学的研究非常有必要的。
The radiation damage to human are highly dependent on the energy distributionand a series biological and chemical process in body. Once DNA was established as themolecule that encodes the genetic instructions used in the development and functioningof all known living organism and many viruses, it was suggested as the critical target.This was the start of the target theory, which states that there is a critical point in the cellthat must be hit in order to induce cell death, and radiation damage outside of this targetshould not cause cell death. For many years it has been thought that DNA is the criticaltarget in a cell exposed to radiation, and although much evidence has accumulated tosuggest that there are other targets within the cell that can lead to significant damage,DNA is still of critical importance. Cell is the basic unit of human body and the innerenvironment of cell has influences on radiation effect. Thus, it’s necessary to study theradiation mechanism on cell level.
This paper is to establish a method to modeling a single cell, which can be appliedin Monte Carlo simulation.
Materials and Methods: KB cell, as being typically tumor cells, is chosen as ourresearch object. After the cells are cultured and stained, images are taken by confocalmicroscopy. Data is extracted from images and imported into Geant4for modeling.Mean specific energy in nucleus and cytoplasm is calculated separately.
Results:7single cells are analyzed. Considering calculating time and accuracy,the resolution scales are set in the range of0.3-0.4μm and the number of αparticle with3MeV energy is set to be200.The calculating results shows that by a single particle hit,the mean specific energy in nucleus is0.209Gy and that in cytoplasm is0.044Gy.
Conclusion: the modeling method we developed is practical and universal, inwhich the density of nucleus and cell shape effect the calculating results a lot.
This study is based on open-source software and the results are in agreement withpublished data.
引文
[1] Blau M. and Altenburger K.. Uber einige Wirkungen von Strahlen[J]. II. Z.Phys.1922.12:315-329.
[2] Lea, D.E.. Actions of Radiations on Living Cells[M]. Cambridge: CambridgeUniversity Press.1946.
[3] Marshell M, Gibson J. A., and Holt P.D.. An analysis of the target theory ofLea with modern data. Int J Radiat Biol Relat Stud Phys Chem Med.1970[J].18(2):127-38,
[4] Puck T T and Marcus P. I.. Action of Xrays on mammalian cells[J]. Journal ofExperimental Medicine.1956.103:653-666,
[5] Lett J.T,, Stacey K. A., and Alexander P.. Cross-linking of drydeoxyribonucleic acids by electrons[J]. Radiation Research.1961.14:349,
[6] Joiner M, Kogel A.V.临床放射生物学基础[M].北京:军事医学科学出版社.2010:13-19.
[7]刘树铮.医学放射生物学[M].北京:原子能出版社.2006:47-62.
[8]李士骏.电离辐射剂量学基础[M].苏州:苏州大学出版社.2008:22-47.
[9] ICRU. ICRU report No.85: Fundamental Quantities and Units for IonizingRadiation[R].Journal of the ICRU,Oxford University Press.2011.11(1).
[10] A.M.Kellerer. Microdosimetry:Reflections on Harald Rossi[J]. RadiationProtection Dosimetry.2002:99(1-4):17-22.
[11] ICRU. ICRU report No.36:Microdosimetry[R]. International Commission onRadioation Units and Measurements.1983.
[12] El Naqa I, Pater P, Seuntjens J.Monte Carlo role in radiobiological modellingof radiotherapy outcomes[J]. Phys Med Biol.2012.57(11):75-97.
[13]林辉,吴东升,徐元英,景佳,许良凤.单细胞模型微观剂量学的MonteCarlo模拟研究[J].辐射研究与辐射工艺学报,2010,28(6):339-344.
[14]田志恒.辐射剂量学[M].原子能出版社.1992.
[15] ICRU. ICRU report No.33:Radiation Quantities and Units[R]. InternationalCommission on Radioation Units and Measurements,1980.
[16] ICRU. ICRU report No.60:Fundamental Quantities and Units for IonizingRadiation[R]. International Commission on Radioation Units and Measurements.1998.
[17] ICRU. ICRU report No.51:Quantities and Units in Radiation ProtectionDosimetry[R]. International Commission on Radioation Units and Measurements.1993.
[18] H. Rabus,H. Nettelbeck. Nanodosimetry:Bridging the gap to radiationbiophysics[J]. Radiation Measurements.2011.46(9):893–897.
[19] H. Rossi and Zaider. Microdosimetry and Its Applications[M]. Heidelberg:Springer-Verlag.1996:53-60.
[20] L.Lindborg and H.Nikjoo. Microdosimetry and radiation qualitydeterminations in radiation protection and radiation therapy[J]. Radiation ProtectionDosimetry.2011.143(2-4):402-408.
[21] Wang CK.The progress of radiobiological models in modern radiotherapywith emphasis on the uncertainty issue[J].Mutat Res.2010.704(1-3):175-181.
[22] D.J.Brenner,L.R.Hlatky,P.J.Hahnfeldt, et. al. The Linear-Quadratic Modeland Most Other Common Radiobiological Models Result in Similar Predictions ofTime-Dose Relationships[J]. Radiation Research.1998.150(1):83-91.
[23] J. Fowler. The Linear-quadratic Formula and Progress in FractionatedRadiotherapy[J]. British Journal of Radiology.1989.62(740):679-694.
[24] Yaes R. J.,Patel P.,Maruyama Y. On using the linearquadratic model in dailyclinical practice[J]. Int J Radiat Oncol Biol Phys.1991.20(6):1353-1362.
[25]涂彧.放射治疗物理学[M].原子能出版社.2010.
[26] A.M. Kellerer,H. Rossi. A generalized formulation of dual radiation action[J].Radiation Research.1978.178(2):204-213.
[27] Hawkins. A microdosimetric-kinetic model of cell death from exposure toionizing radiation of any LET with experimental and clinical applications[J]. Int JRadiat Biol.1996.69(6):739-755.
[28] Kase Y,Kanematsu N,Kanai T. Biological dose calculation with Monte Carlophysics simulation for heavy-ion radiotherapy[J]. Phys Med Biol.2006.51(24):467-475.
[29] T Sato, Y Kase, R Watanabe,et al. Biological Dose Estimation forCharged-Particle Therapy Using an Improved PHITS Code Coupled with aMicrodosimetric Kinetic Model[J]. Radiation Research.2009.171(1):107-117.
[30]Koji Niita, T Sato, Hiroshi Iwase, et al. PHITS-a particle and heavy iontransport code system[J]. Radiation Measurements.2006.41(9-10):1080-1090.
[31] Thilo Els sser, Michael Kr mer, Michael Scholz. Accuracy of the LocalEffect Model for the Prediction of Biologic Effects of Carbon Ion Beams In Vitro and InVivo[J]. Int J Radiat Oncol Biol Phys.2008.71(3):866-872.
[32] MICROS2009. Book of Abstract and Scientific Programme[R]. RadiationProtection Dosimetry.2011.143(2-4):557-561.
[33]徐勇军,刘森林,陈超峰等.空间高能重带电粒子微剂量学基础研究[J].中国原子能科学研究院年报.2005.226.
[34]方美华,魏志勇,杨浩等.空间辐射场中高能Fe离子微剂量学分析[J].航天器环境工程.2008.25:129-133.
[35]田源.核医学微剂量估算系统[D].北京协和医院.2008.
[36]纪纲.中子辐射的微剂量学实验研究[J].国外医学放射医学核医学分册.2000.24(1):28-31
[37]李素云.从微剂量学角度探讨氡子体照射危险评价中的不确定性[J].辐射防护.2000.20(4):240-243.
[38]张文仲.电离辐射粒子在人体组织中能量沉积的微剂量学研究[D].中国人民解放军军事医学科学院.2003:1-19.
[39]马云志.电离辐射生物效应的理论研究[D].北京师范大学.2005:27-46.
[40]卢希庭.原子核物理[M].原子能出版社.2010.
[41] Hill MA. Radiation damage to DNA: the importance of track structure.RadiatMeas.1999.31(1-6):15-23.
[42] H.Nikjoo,S. Uehara,D. Emfietzoglou et al. Truck-structure codes in radiationresearch[J]. Radiation Measurements.2006.41(9-10):1052-1074.
[43] Tai, H, Bichsel, H, Wilson, J W, et.al. Comparison of stopping power andrange databases for radiation transport study[R].NASA technical paper3644.Washington, DC: NASA Headquarters,1997.
[44] F Ballarini,D Alloni,A Facoetti and A Ottolenghi. Heavy-ion effects: fromtrack structure to DNA and chromosome damage[J]. New Journal of Physics.2008.10:1-17.
[45] Francis A. Cucinotta,Hooshang Nikjoo,Dudley T. Goodhead. Applications ofamorphous track models in radiation biology[J]. Radiat Environ Biophys.1999.38(2):81-92.
[46] Agostinelli S., et al, GEANT4-a simulation tooldkot[J]. Nucl. Instr. Meth.2003.506:250-303.
[47] Allison J., et al. GEANT4Developments and Applications[J]. IEE Trans.Nucl. Sci.2006.53:270-278.
[48] Agostinellia S. Allisonas J., Amakoe K.. GEANT4—a simulation toolkit[J].Nuclear Instruments and Methods in Physics Research Section A: Accelerators,Spectrometers, Detectors and Associated Equipment.2003.503:250-303.
[49] Allison J., Amako K., Apostolakis J.. GEANT4developments andapplications[J]. IEEE TRANSACTIONS ON NUCLEAR SCIENCE.2006.53:270-278.
[50] Freudenber R., Wendisch M., Kotzerke J.. GEANT4-Simulations for cellulardosimetry in nuclear medicine[J]. Z. Med. Phys.2011.21:281–289.
[51] Beaton L.A., Burn T.A., Stocki T.J., Chauhan V., Wilkins R.C.. Developmentand characterization of an in vitro alpha radiation exposure system[J]. Phys. Med. Biol.2011.56:3645–3658.
[52] Chauvie S., Francis Z., Guatelli S., Incerti S., Mascialino B., et al.. GEANT4physics processes for microdosimetry simulation: design foundation andimplementation of the first set of models[J]. IEEE Trans. Nucl. Sci.2007.54:2619-2628.
[53] Incerti S., Barberet Ph., Villeneuve R., Aguer P., Gontier E., et al.. Simulationof cellular irradiation with the CENBG microbeam line using GEANT4[J]. IEEE Trans.Nucl. Sci.2004.51:1395-1401.
[54] Incerti S., Seznec H., Simon M., Barberet Ph., Habchi C., Moretto Ph.. MonteCarlo dosimetry for targeted irradiation of individual cells using a microbeam facility[J].Rad. Prot. Dos.2009.133:2-11.
[55] Karamitros M., Mantero A., Incerti S.. Modeling Radiation Chemistry in theGEANT4Toolkit. Progress in nuclear science and technology[J].2011.2:503-508.
[56] Miller J.H., Resat M. S., Metting N.F., Wei K.,Wilson W.E. Monte Carlosimulation of single-cell irradiation by an electron microbeam[J].Radiat EnvironBiophys.2000.39:173–177.
[57] Radford IR, Hodgson GS, Matthews JP. Critical DNA target size model ofionizing radiation-induced mammalian cell death[J]. Int J Radiat Biol.1988.54(1):63-79.
[58] Greenstock CL, Whitehouse RP. Radiosensitizers as probes of DNA damageand cell killing[J]. Int. J. Radiat. Biol. Relat. Stud. Phys. Chem. Med..1985.48(5):701-10.
[59] Matile, P.. Vacuoles, lysosomes of Neurospora[J]. Cytobiologie.1971.3:324-330.
[60] Incerti S., Gault N., Habchi C., Lefaix J.L., Moretto Ph., et al.. A comparisonof cellular irradiation techniques with alpha particles using the GEANT4Monte Carlosimulation toolkit[J]. Rad. Prot. Dos.2006.122(1-4):327-329.
[61Archambault L., Beaulieu L., Carrier J. F.. Overview of GEANT4applicationsin medical physics[J]. Nuclear Science Symposium Conference Record.2003.3:1743-1745.
[62] Rademakers F., Brun R.. ROOT: An Object-Oriented Data AnalysisFramework[J]. Nuclear Instruments and Methods in Physics Research Section A:Accelerators, Spectrometers, Detectors and Associated Equipment.1998.389:81-86.
[63] Collins T.J.. ImageJ for microscopy[J]. BioTechniques.2007.43:25-30.
[64]宋玉丹,容幸福,秦志钰.利用ImageJ提取目标物平面图像外轮廓昀方法[J].中国高新技术企业.2008(1):104.
[65]盛骤,谢式千,潘承毅.概率论与数理统计[M].北京:高等教育出版社.2008:178-218.
[66] Tea-Yuan H., Chin-Yuan H..On the joint distribution of Grubbs' statistics[J].Annals of the Institute of Statistical Mathematics.1994.46:769-775.
[67] Incerti S., Baldacchino G., Bernal M.,et al.the GEANT4-dna project[J]. Int. J.Model. Simul. Sci. Comput.2010.1:157-158.
[68] Antcheva I., Ballintijn M., Bellenot B.. ROOT—A C++framework forpetabyte data storage, statistical analysis and visualization[J]. Computer PhysicsCommunications.2011.182:1384-1385.
[69] Arne M..Dosimetry for radiation processing. International Journal ofRadiation Applications and Instrumentation[J]. Part C. Radiation Physics and Chemistry.1986.28:521-529.
[70] Sutton M. L., Hendry J. H.. The Radiotherapy of Malignant Disease[M].1991:33-55.
[71] Ivanov V. I..II All-Union Conference on Microdosimetry[M]. Soviet AtomicEnergy.1973.35:954-955.