光学学报, 2007, 27 (11): 2091, 网络出版: 2007-11-12  

碘化汞材料固有空间分辨的蒙特卡罗模拟研究

Inherent Spatial Resolution of Mercuric Iodide by Monte Carlo Simulation
作者单位
1 华中科技大学光电子科学与工程学院, 武汉 430074
2 深圳大学光电工程学院, 深圳 518060
摘要
采用蒙特卡罗方法模拟了直接转换X射线探测材料HgI2在医用X射线范围的固有空间分辨性能,模拟基于最新版本的EGSnrc模拟软件的用户代码DOSRZnrc,模拟了HgI2材料对无限小锥束入射X射线的调制传递函数(MTF)。考虑到荧光光子和散射光子重吸收,高速电子射程扩展以及离轴X射线入射对空间分辨力的影响,把模拟结果和文献解析方法获得的结果做了对比,两者符合较好。模拟结果表明,初级高速电子射程和入射角度对材料固有空间分辨力影响很大,材料分辨对入射X光子能量很敏感,高能时分辨力特性急剧变差,而对材料厚度很不敏感。相对于非晶硒(α-Se),HgI2材料具有更好的固有空间分辨力,尤其在50 keV能量以上时。在fMTF=0.5时,能量为20 keV,50 keV和100 keV的X射线入射,HgI2和非晶Se固有空间分辨力分别为390 lp/mm,170 lp/mm,52 lp/mm和390 lp/mm,80 lp/mm,22 lp/mm。
Abstract
Mercuric iodide (HgI2), as a semiconductor detecting material directly absorbing X-ray, its inherent spatial resolution has been investigated for the medical diagnosis X-ray energy. The Monte-Carlo simulation is performed with an infinitesimal pencil-beam of X-ray incident on the HgI2 slab to determine its modulation transfer function(MTF). The simulation is based on the user code DOSRZnrc of the latest version of the EGSnrc, and these effects on HgI2 spatial resolution by the reabsorptions of fluorescence and scattered photons, expanded ranges of fast photoelectrons and off-axis incident angle, are considered and the simulated results accord with the literature analytic results well. The simulation results show that the ranges of primary fast photoelectrons and off-axis incident angle can affect the spatial resolution of the material greatly and the spatial resolution is sensitive to the incident X-ray energy since the modulation transfer function (MTF) decreases greatly with the increasing of X-ray energy, which however depends hardly on the thickness of the film. Compared with amorphous Se, HgI2 has a higher inherent spatial resolution, especially for above 50 keV X-ray energy. When fMTF=0.5, for X-ray photon energy of 20 keV, 50 keV and 100 keV, the inherent spatial resolutions of HgI2 and amorphous Se are 390 lp/mm, 170 lp/mm,52 lp/mm and 390 lp/mm, 80 lp/mm, 22 lp/mm, respectively.
参考文献

[1] . J. Davis, D. Gao, T. E. Gureyev et al.. Phase-contrast imaging of weakly absorbing materials using hard X-rays[J]. Nature, 1995, 373(6515): 595-598.

[2] . . Phase-contrast X-ray computed tomography for observing biological soft tissues[J]. Nature Med., 1996, 2: 473-475.

[3] . . Phase retrieval and differential phase-contrast imaging with low-brilliance X-ray sources[J]. Nature Physics, 2006, 2: 258-261.

[4] . Hartsough, Jan S. Iwanczyk, Bradley E. Patt et.al.. Imaging performance of mercuric iodide polycrystalline films[J]. IEEE Transactions on Nuclear Science, 2004, 51(4): 1812-1816.

[5] Robert A. Street, Marcelo Mulato, Steve E. Ready et al.. High resolution X-ray image sensors based on HgI2[C]. Proc. SPIE, 2000, 4142: 189~196

[6] . Zentai, M. Schieber, L. Partain et al.. Large area mercuric iodide and lead iodide X-ray detectors for medical and non-destructive industrial imaging[J]. J. Crystal Growth, 2005, 275: 1327-1331.

[7] . Que, J. A. Rowlands. X-ray imaging using amorphous selenium: Inherent spatial resolution[J]. Med. Phys., 1995, 22(4): 365-374.

[8] . Sakellaris, G. Spyrou, G. Tzanakos et al.. Monte Carlo simulation of primary electron production inside an a-selenium detector for X-ray mammography: physics[J]. Phys. Med. Biol., 2005, 50: 3717-3738.

[9] . Hoheisela, J. Gierschb, P. Bernhardta. Intrinsic spatial resolution of semiconductor X-ray detectors: a simulation study[J]. Nuclear Instruments and Methods in Physics Research A, 2004, 531: 75-81.

[10] . Rossi, M. Sanchez del Rio, P. Fajardo et al.. Monte Carlo simulation of the X-ray response of a germanium microstrip detector with energy and position resolution[J]. Nuclear Instruments and Methods in Physics Research A, 1999, 432: 130-137.

[11] I. Kawrakow, D. W. O. Rogers. The EGSnrc code system: Monte Carlo simulation of electron and photon transport[R]. Technical Report PIRS-701, National Research Council of Canada, Ottawa, 2000

[12] . Kawrakow. Accurate condensed history Monte Carlo simulation of electron transport. I: EGSnrc, the new EGS4 version[J]. Med. Phys., 2000, 27(3): 485-498.

[13] . Hoheisela, A. Korn, J. Giersch. Influence of backscattering on the spatial resolution of semiconductor X-ray detectors[J]. Nuclear Instruments and Methods in Physics Research A, 2005, 546: 252-257.

[14] Alexander Korn, Juergen Gierscha, Martin Hoheisel. Simulation of internal backscatter effects on MTF and SNR of pixelated photon-counting detectors[C]. Proc. SPIE, 2005, 5745: 292~298

[15] Wei Biao, Zhou Mi, Feng Peng et al.. Study on CsI(Tl) scintillating crystal for X-ray high-resolution detection with Monte Carlo method[J]. Acta Optica Sinica, 2006, 26(9): 1429~1434 (in Chinese)
魏彪,周密, 冯鹏 等. X光高分辨探测用CsI(Tl)晶体的蒙特卡罗模拟研究[J]. 光学学报, 2006, 26(9): 1429~1434

[16] Shao Junming, Lu Hongnian, Cai Hui. A piont spread function model for X-ray imaging[J]. Acta Optica Sinica, 2005, 25(8): 1148~1152 (in Chinese)
邵军明,路宏年,蔡 慧. X射线成像的一种点扩展函数模型[J]. 光学学报, 2005, 25(8): 1148~1152

[17] Guo Jinchuan, Niu Hanben, Zhou Bin. Influence of conglutination of CsI∶Na columns on the resolution properties[J]. Acta Photonica Sinica, 2001, 30(10): 1214~1217(in Chinese)
郭金川,牛憨笨,周彬. 晶柱粘连对CsI∶Na转换屏分辨特性的影响[J]. 光子学报, 2001, 30(10): 1214~1217

[18] Mu Weibing, Chen Panxun. Simulative calculation of the dose enhancement factor of W-SiO2 and Ta-SiO2 interface[J]. High Power Laser and Particle Beams, 2001, 13(1): 15~18 (in Chinese)
牟维兵,陈盘训. X射线在重金属二氧化硅界面的剂量增强的模拟计算[J]. 强激光与粒子束, 2001, 13(1): 15~18

[19] . . Primary study of Monte Carlo simulation on CdZnTe nuclear detector[J]. High Energy Physics and Nuclear Physics, 2004, 28(2): 191-195.

[20] . Kirk, A. Haghigat, R. Jeraj et al.. SU-FF-T-378: Radiation transport software for medical physics studies[J]. Med. Phys., 2006, 33(6): 2132-2133.

桂建保, 郭金川, 杨勤劳, 刘鑫, 牛憨笨. 碘化汞材料固有空间分辨的蒙特卡罗模拟研究[J]. 光学学报, 2007, 27(11): 2091. 桂建保, 郭金川, 杨勤劳, 刘鑫, 牛憨笨. Inherent Spatial Resolution of Mercuric Iodide by Monte Carlo Simulation[J]. Acta Optica Sinica, 2007, 27(11): 2091.

关于本站 Cookie 的使用提示

中国光学期刊网使用基于 cookie 的技术来更好地为您提供各项服务,点击此处了解我们的隐私策略。 如您需继续使用本网站,请您授权我们使用本地 cookie 来保存部分信息。
全站搜索
您最值得信赖的光电行业旗舰网络服务平台!