工业用γ射线影像板的金属增感与色心研究
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摘要
上世纪80年代初，日本Fuji Film公司推出商用影像板。其曝光剂量低、影像灰度丰富，分辨率高，且图像可数字化处理并可储存于光盘中，易于存储和检查，影像板可反复使用上万次。上个世纪末，影像板以其优良的性能为人们所青睐并在医疗领域迅速推广。快速、清晰和数字化的射线探测不仅是医疗也是工业探伤所急切需要的。现在工业探伤仍然使用古老的荧光胶片来探测射线影像，探测时间长、影像质量差，很难满足人们对快速、高质影像探测的需求。影像板在低于胶片影像的1／7的曝光剂量就能得到清晰影像，尤其能显著改善荧光胶片γ射线探测时所需时间长的问题。
本文首先研究了影像板在工业探伤领域应用的可行性，然后研究了如何进一步缩短曝光剂量得到更清晰的影像，来突现影像板在工业探伤领域的优点，主要从增感和改善影像板材料性能两个方面研究。全文主要内容如下：
1、在国内，关于影像板在工业无损探伤方面的研究还未见报道。本文考察了影像板工业射线无损探测时的影像质量和探测条件。用我们新研制的光激励发光材料做成的影像板代替感光胶片使用，得到了清晰的X射线和γ射线的焊缝透射影像，这在国内还是首次。本文还考察了胶片和影像板的探测过程和影像处理工序，得出了目前影像板在工业探伤上的主要优势与障碍。
2、目前胶片使用增感法来提高其射线利用率，缩短曝光时间。对影像板的增感研究还未见报道。本文研究对比了应用于荧光胶片的两种增感方法。认为对高能γ射线探测时，金属增感法适用于影像板且能保证较好的影像清晰度。
3、研究比较了两种常用金属增感材料(钽和铅)的前屏增感系数。研究了不同厚度的前铅箔屏对影像板光激励发光强度的影响。用理论公式计算了加入前铅箔产生的各种二次能量对影像板的作用，分析了加入前铅箔对提高影像板光激励发光强度的原因。
4、研究了铅的后屏增感对影像板光激励发光强度的影响，确定后增感屏在提高影响板影像质量方面的作用。计算得出后铅屏主要屏蔽的是环境的特征X射线。
5、从结构原理上研究了材料陷阱结构对影像板的激励光波长和射线存储能力的影响。提出了掺杂杂质离子的价态是影像板激励光波长红移的主要因素。首次提出高价态主族杂质离子掺杂的色心结构的光激励波长红移量要高于低价态主族杂质离子掺杂色心结构的光激励波长红移量。首次提出掺杂高价态杂质离子也可能是提高影像板及其它光存储材料光激励发光强度的一个途径。
In the 80~(th), Fuji-Film Corporation invented the Imaging Plate (IP) for commercial use. IP has many merits over the traditional fluorescent film for its lower exposure dosage, richer grayness, easier digitalization and repeatable use. IP had been widely acknowledged and had gradually prevailed in medical fields in the end of last century.
Clear and low exposure dosage radiography is not only the need of medical fields but also of the industrial non-destructive detection. The traditional fluorescent film now used in the non-destructive detection cannot satisfy the need of modern radiography requests for its low image quality, long detection time and serous pollution problems. Imaging plate, especially used for the purpose of detecting thick work pieces, can obviously reduce the exposure duration and enhance the image quality for its excellent properties.
How to obtain clearer image by lower exposure dosage was emphasized in this paper. The feasibility of applying of IP in industrial non-destructive detection was firstly studied and the foil intensifying screen and F-centers were mainly focused on. The main works are listed as follows:
1. Newly developed phosphor was made to Imaging Plate and clear X-ray andγ-ray images were obtained, which is the first time in domestic country. Themain merits and barriers of IP were also discussed in its way of industrial appliance.
2. Foil intensifying manner used on films was studied to intensify IP. No such work has been done before.
3. Intensifying coefficients of several fore- intensifying foils were measured. The relationship between the thickness of the foils and the photo-stimulated luminescence intensity was studied. Quantitative calculation of the secondary radiation on imaging plate after adding the foil was made by the interaction theories of the matter and radiation.
4. The effect of back-intensifying foil on the PSL was studied, and the effect of back-screen on the imaging quality of the imaging plate was also discussed. The main factor of reducing the quality of image was sure to be the characteristic X-ray of the surroundings but not the back-scattering radiations.
5. The effect of electron traps on the radiation storage and the PSL intensity was systematically studied. The theory that the PSL of high valent cations doped electron traps is always higher than the lower valent cations doped ones was put forth for the first time. It is also the first time to propose that the doped high valent cation impurities might be a factor of PSL enhancement of IP.
本文首先研究了影像板在工业探伤领域应用的可行性，然后研究了如何进一步缩短曝光剂量得到更清晰的影像，来突现影像板在工业探伤领域的优点，主要从增感和改善影像板材料性能两个方面研究。全文主要内容如下：
1、在国内，关于影像板在工业无损探伤方面的研究还未见报道。本文考察了影像板工业射线无损探测时的影像质量和探测条件。用我们新研制的光激励发光材料做成的影像板代替感光胶片使用，得到了清晰的X射线和γ射线的焊缝透射影像，这在国内还是首次。本文还考察了胶片和影像板的探测过程和影像处理工序，得出了目前影像板在工业探伤上的主要优势与障碍。
2、目前胶片使用增感法来提高其射线利用率，缩短曝光时间。对影像板的增感研究还未见报道。本文研究对比了应用于荧光胶片的两种增感方法。认为对高能γ射线探测时，金属增感法适用于影像板且能保证较好的影像清晰度。
3、研究比较了两种常用金属增感材料(钽和铅)的前屏增感系数。研究了不同厚度的前铅箔屏对影像板光激励发光强度的影响。用理论公式计算了加入前铅箔产生的各种二次能量对影像板的作用，分析了加入前铅箔对提高影像板光激励发光强度的原因。
4、研究了铅的后屏增感对影像板光激励发光强度的影响，确定后增感屏在提高影响板影像质量方面的作用。计算得出后铅屏主要屏蔽的是环境的特征X射线。
5、从结构原理上研究了材料陷阱结构对影像板的激励光波长和射线存储能力的影响。提出了掺杂杂质离子的价态是影像板激励光波长红移的主要因素。首次提出高价态主族杂质离子掺杂的色心结构的光激励波长红移量要高于低价态主族杂质离子掺杂色心结构的光激励波长红移量。首次提出掺杂高价态杂质离子也可能是提高影像板及其它光存储材料光激励发光强度的一个途径。
In the 80~(th), Fuji-Film Corporation invented the Imaging Plate (IP) for commercial use. IP has many merits over the traditional fluorescent film for its lower exposure dosage, richer grayness, easier digitalization and repeatable use. IP had been widely acknowledged and had gradually prevailed in medical fields in the end of last century.
Clear and low exposure dosage radiography is not only the need of medical fields but also of the industrial non-destructive detection. The traditional fluorescent film now used in the non-destructive detection cannot satisfy the need of modern radiography requests for its low image quality, long detection time and serous pollution problems. Imaging plate, especially used for the purpose of detecting thick work pieces, can obviously reduce the exposure duration and enhance the image quality for its excellent properties.
How to obtain clearer image by lower exposure dosage was emphasized in this paper. The feasibility of applying of IP in industrial non-destructive detection was firstly studied and the foil intensifying screen and F-centers were mainly focused on. The main works are listed as follows:
1. Newly developed phosphor was made to Imaging Plate and clear X-ray andγ-ray images were obtained, which is the first time in domestic country. Themain merits and barriers of IP were also discussed in its way of industrial appliance.
2. Foil intensifying manner used on films was studied to intensify IP. No such work has been done before.
3. Intensifying coefficients of several fore- intensifying foils were measured. The relationship between the thickness of the foils and the photo-stimulated luminescence intensity was studied. Quantitative calculation of the secondary radiation on imaging plate after adding the foil was made by the interaction theories of the matter and radiation.
4. The effect of back-intensifying foil on the PSL was studied, and the effect of back-screen on the imaging quality of the imaging plate was also discussed. The main factor of reducing the quality of image was sure to be the characteristic X-ray of the surroundings but not the back-scattering radiations.
5. The effect of electron traps on the radiation storage and the PSL intensity was systematically studied. The theory that the PSL of high valent cations doped electron traps is always higher than the lower valent cations doped ones was put forth for the first time. It is also the first time to propose that the doped high valent cation impurities might be a factor of PSL enhancement of IP.
引文
[1] A. L. N. Sterels and T. Pingault, "BaFCI: Eu, a new phosphor for X-ray intensifying screens", Philips Res. Repts 1975, 30, 277-290
[2] 王振家《中国科学院理学博士论文》 (1995)
[3] Kenji Takahashi, Katsuhiro Kohda, Junji Miyahara, "Machanism of photostimulated luminescence inBaFX: Eu(X=Cl, Br) phosphors", Journal of Luminescence 31&32(1984), 266-268
[4] Yasuo Iwabuchi, Nobufumi Mori, et al. "Mechanism of Photo stimulated Luminescence Process in BaFBr: Eu~(2+) Phosphors", Jpn. J. Appl. Phys. 1994, 33: 178-185
[5] 李家伟、陈积懋编，《无损检测手册》2001，机械工业出版社，第一版，p44-150
[6] J. J. Munroll et al, Mobile Computed Topography System for Industrial Applications, Material Evaluation, May1990, Vol. 48, No. 5. pp. 568, 570-572
[7] P. Engler and W. D. Friedman, Review of Dual Energy Computed Topography Technique, ibid, May 1990, Vol. 48, No5. pp. 623-629
[8] Neutron Radiography Handbook, Edited by P. Von Der Hardt and H. Rotteger, D. Reidel Publishing Company, 1981
[9] A. M. Koehler and H. Berger, Proton Radiography, in Research Techniques in Nondestructive Testing. Vol. 2. Edited by R. S. Sharpen, Academic Press, 1973, pp. 1-30
[10] S Ekinci, N Bas and A Yildirim, Investigation of Thin objects by Electron Radiography, Insight, Sep 1995, Vol. 37, No. 9, pp. 695-697
[11] E. Borg, H. G. Grondahi. "On the dynamic range of different X-ray photon detectors in intra-oral radiography. A comparison of image quality in film, charge couples device and storage phosphor systems" Dentomxillofac. Radio. 1996 Vol. 25. No. 2, 82-88
[12] Miklos Z. Kiss, Dale E. Sayers, et al. "Comparison of X- ray detectors for a diffraction enhanced imaging system" Nuclear Instruments and Methods in Physics Research A 491(2002) 280-290
[13] M. Doyama, M. Inoue, et al "Imaging plate as position-sensitive detector of positron and γ ray" Nuclear Instruments and Methods in Physics Research A 448(2000)554-557
[14] Saito K., Baba M., et al "Fast neutron profiling with imaging plate" CYRIC Annual Report 1996
[15] N. Niimura. "Neutron structural biology" J. phy. chem. Sol. 60, (1999) 1265-1271
[16] C. Thilmann, I. A. Adamietz, el al "In VIVO Dose Increase in the Presence of Dental Alloys During 60Co-Gamma-ray Therapy of the Oral Cavity" Medical Dosimetry, 1996. Vol. 21. No. 3. pp149-154
[17] Ulku Bulubay and A. Beril Tugrul "Quantitative evaluation of intensifying screens materials inCO-6Oradiography for steel parts" NDT&E International. 1998. Vol. 31, No. 3. pp193-199,
[18] 日本无损检测协会编 《射线探伤A》李衍译．1988，第一版，机械工业出版社出版p18-20
[19] 王振家 《中国科学院理学博士论文》(1995)
[20] A. L. N. Sterels and T. Pingault, "BaFCI:Eu, a new phosphor for X-ray intensifying screens", Pbilips Res. Repts 30, 1975, 277-290
[21] 李新作《无损检测原理和方法》1989，第一版，云南大学出版社p148-150
[22] Yi Wang, Jingjin Wang, Kuilu Wang et. al "Monte Carlo simulation of image properties of an X-ray intensifying screen" Nuclear Instruments and Methods in Physics Research A 448(2000) 567-570
[22] 日本无损检测协会编 《射线探伤B》李衍译．1988，第一版，机械工业出版社出版p165-166
[23] 李新作《无损检测原理和方法》1989，第一版，云南大学出版社 p155-159
[24] 张丽平《天津理工学院硕士论文》2004年6月
[25] 刘运祚主编《常用放射性核素衰变纲图》，1982，第一版，原子能出版社P447-521
[26] 方书淦，张启仁《晶体色心物理学》1988，第一版，上海交通大学出版社 p8-87
[27] Luty. F., "Physics of Color Centers" Ed. by Flowler, W. B., Acad., Press1968
[28] Rosenberger, F., Luty, F.: Sol. Stat. Commum., 7(1969)249
[29] Kleefstra, M.: J. Phys. Chem. Sol. 24, (1963) 1567
[30] Hartel, H., Luty, F.: Z. Phys. 182, (1964) 111
[31] Bushnell, J. C.: PH. D. Thesis Univ of Illinois, Urbrara(1964)
[32] Fuji photo film Co. Ltd. "Tetradecahedral rare earth activated alkaline earth metal fluoride halide-based stimulable phosphor and radiographic image converting panel", 16.01.2001. Japan: 2001-011439
[33] Fuji photo film Co. Ltd. "Europium activated alkaline earth metal fluoride halide-based phosphor and radiation image converting panel", 12.12.2001, Japan: 2001-345151
[34] Fuji photo film Co. Ltd. "Tetra-decahedral rare earth activated alkaline earth metal fluoride halide accelerated phosphor and radiation image converting panel" , 19.05.1998, Japan: 10-130640
[35] Konica Corp. "Stimulable phosphor and its production and panel for converting radiation image and its production", 26.05.2000. Japan: 2000-144128
[36] Agfa-Geraert, N. Y. "photostimulable phosphor screen suited for dual energy recording", 01.30.2001, USA: 6180949
[37] Kiyoshi Inoue, Yasuhiro Kondoand Nobufumi Mori; "F (Br) center inNa-doped BaFBr: Eu~(2+)" [J]. Jpn. J. Appl. Phys, (2000) 39(12): 6606-6607
[38] S. Schweizer, P. Willems and P. J. Leblans; "Electron traps in Ca~(2+) or Sr~(2+)— doped BaFBr: Eu~(2+) x-ray storage phosphor". [J]. Appl. Phys, 1996, 79 (8): 4157-4165
[39] 余华《天津理工学院硕士论文》2002年7月
[40] 熊光楠，娄素云等《BaFBr：Eu~(2+)中电子陷阱的研究》天津理工学院报Sep 1998，Vol14．No3
[41] HuaYu, GuangnanXiong, et. al; "Properties of F (Br-) centers inBaFBr: Eu~(2+) doped with Al~(3+)" [J]. Chin. J. Lumin, 2002, 23(6): 599-602
[42] Guangnan Xiong, Suhua Gao, et. al; "Red shift of PSL spectra by Al~(3+) doped in BaFBr: Eu~(2+)" [J]. Soc. Inform. Displ, 2000, 8(1): 23-25
[43] 余华，熊光楠等《无机晶体材料中色心的形成及其存储机理的研究》天津理工学院学报，Mar2001，Vol．17，No．1
[44] Zheng Zhen, Xiong Guang-nan "Electron Traps in Si~(4+) Doped BaFBr: Eu~(2+) X-Ray Storage Phosphor" J Opt electronics-Laser, 2004, Vol. 15. No. 1
[45] B Sundarakkannan, R Kesavamoorthy, N. Dharmarasu, et. al; Raman scattering investigation of surface modification in heat treated BaFC1 [J], Phys. Star. Sol. (a) 2000, 177: 567-573
[46] S. Munekawa and T. Higashi; "The Investigation Report about Imaging Plate, issued by Japan Synchrotron Radiation Research Institute, 1992, 235
[2] 王振家《中国科学院理学博士论文》 (1995)
[3] Kenji Takahashi, Katsuhiro Kohda, Junji Miyahara, "Machanism of photostimulated luminescence inBaFX: Eu(X=Cl, Br) phosphors", Journal of Luminescence 31&32(1984), 266-268
[4] Yasuo Iwabuchi, Nobufumi Mori, et al. "Mechanism of Photo stimulated Luminescence Process in BaFBr: Eu~(2+) Phosphors", Jpn. J. Appl. Phys. 1994, 33: 178-185
[5] 李家伟、陈积懋编，《无损检测手册》2001，机械工业出版社，第一版，p44-150
[6] J. J. Munroll et al, Mobile Computed Topography System for Industrial Applications, Material Evaluation, May1990, Vol. 48, No. 5. pp. 568, 570-572
[7] P. Engler and W. D. Friedman, Review of Dual Energy Computed Topography Technique, ibid, May 1990, Vol. 48, No5. pp. 623-629
[8] Neutron Radiography Handbook, Edited by P. Von Der Hardt and H. Rotteger, D. Reidel Publishing Company, 1981
[9] A. M. Koehler and H. Berger, Proton Radiography, in Research Techniques in Nondestructive Testing. Vol. 2. Edited by R. S. Sharpen, Academic Press, 1973, pp. 1-30
[10] S Ekinci, N Bas and A Yildirim, Investigation of Thin objects by Electron Radiography, Insight, Sep 1995, Vol. 37, No. 9, pp. 695-697
[11] E. Borg, H. G. Grondahi. "On the dynamic range of different X-ray photon detectors in intra-oral radiography. A comparison of image quality in film, charge couples device and storage phosphor systems" Dentomxillofac. Radio. 1996 Vol. 25. No. 2, 82-88
[12] Miklos Z. Kiss, Dale E. Sayers, et al. "Comparison of X- ray detectors for a diffraction enhanced imaging system" Nuclear Instruments and Methods in Physics Research A 491(2002) 280-290
[13] M. Doyama, M. Inoue, et al "Imaging plate as position-sensitive detector of positron and γ ray" Nuclear Instruments and Methods in Physics Research A 448(2000)554-557
[14] Saito K., Baba M., et al "Fast neutron profiling with imaging plate" CYRIC Annual Report 1996
[15] N. Niimura. "Neutron structural biology" J. phy. chem. Sol. 60, (1999) 1265-1271
[16] C. Thilmann, I. A. Adamietz, el al "In VIVO Dose Increase in the Presence of Dental Alloys During 60Co-Gamma-ray Therapy of the Oral Cavity" Medical Dosimetry, 1996. Vol. 21. No. 3. pp149-154
[17] Ulku Bulubay and A. Beril Tugrul "Quantitative evaluation of intensifying screens materials inCO-6Oradiography for steel parts" NDT&E International. 1998. Vol. 31, No. 3. pp193-199,
[18] 日本无损检测协会编 《射线探伤A》李衍译．1988，第一版，机械工业出版社出版p18-20
[19] 王振家 《中国科学院理学博士论文》(1995)
[20] A. L. N. Sterels and T. Pingault, "BaFCI:Eu, a new phosphor for X-ray intensifying screens", Pbilips Res. Repts 30, 1975, 277-290
[21] 李新作《无损检测原理和方法》1989，第一版，云南大学出版社p148-150
[22] Yi Wang, Jingjin Wang, Kuilu Wang et. al "Monte Carlo simulation of image properties of an X-ray intensifying screen" Nuclear Instruments and Methods in Physics Research A 448(2000) 567-570
[22] 日本无损检测协会编 《射线探伤B》李衍译．1988，第一版，机械工业出版社出版p165-166
[23] 李新作《无损检测原理和方法》1989，第一版，云南大学出版社 p155-159
[24] 张丽平《天津理工学院硕士论文》2004年6月
[25] 刘运祚主编《常用放射性核素衰变纲图》，1982，第一版，原子能出版社P447-521
[26] 方书淦，张启仁《晶体色心物理学》1988，第一版，上海交通大学出版社 p8-87
[27] Luty. F., "Physics of Color Centers" Ed. by Flowler, W. B., Acad., Press1968
[28] Rosenberger, F., Luty, F.: Sol. Stat. Commum., 7(1969)249
[29] Kleefstra, M.: J. Phys. Chem. Sol. 24, (1963) 1567
[30] Hartel, H., Luty, F.: Z. Phys. 182, (1964) 111
[31] Bushnell, J. C.: PH. D. Thesis Univ of Illinois, Urbrara(1964)
[32] Fuji photo film Co. Ltd. "Tetradecahedral rare earth activated alkaline earth metal fluoride halide-based stimulable phosphor and radiographic image converting panel", 16.01.2001. Japan: 2001-011439
[33] Fuji photo film Co. Ltd. "Europium activated alkaline earth metal fluoride halide-based phosphor and radiation image converting panel", 12.12.2001, Japan: 2001-345151
[34] Fuji photo film Co. Ltd. "Tetra-decahedral rare earth activated alkaline earth metal fluoride halide accelerated phosphor and radiation image converting panel" , 19.05.1998, Japan: 10-130640
[35] Konica Corp. "Stimulable phosphor and its production and panel for converting radiation image and its production", 26.05.2000. Japan: 2000-144128
[36] Agfa-Geraert, N. Y. "photostimulable phosphor screen suited for dual energy recording", 01.30.2001, USA: 6180949
[37] Kiyoshi Inoue, Yasuhiro Kondoand Nobufumi Mori; "F (Br) center inNa-doped BaFBr: Eu~(2+)" [J]. Jpn. J. Appl. Phys, (2000) 39(12): 6606-6607
[38] S. Schweizer, P. Willems and P. J. Leblans; "Electron traps in Ca~(2+) or Sr~(2+)— doped BaFBr: Eu~(2+) x-ray storage phosphor". [J]. Appl. Phys, 1996, 79 (8): 4157-4165
[39] 余华《天津理工学院硕士论文》2002年7月
[40] 熊光楠，娄素云等《BaFBr：Eu~(2+)中电子陷阱的研究》天津理工学院报Sep 1998，Vol14．No3
[41] HuaYu, GuangnanXiong, et. al; "Properties of F (Br-) centers inBaFBr: Eu~(2+) doped with Al~(3+)" [J]. Chin. J. Lumin, 2002, 23(6): 599-602
[42] Guangnan Xiong, Suhua Gao, et. al; "Red shift of PSL spectra by Al~(3+) doped in BaFBr: Eu~(2+)" [J]. Soc. Inform. Displ, 2000, 8(1): 23-25
[43] 余华，熊光楠等《无机晶体材料中色心的形成及其存储机理的研究》天津理工学院学报，Mar2001，Vol．17，No．1
[44] Zheng Zhen, Xiong Guang-nan "Electron Traps in Si~(4+) Doped BaFBr: Eu~(2+) X-Ray Storage Phosphor" J Opt electronics-Laser, 2004, Vol. 15. No. 1
[45] B Sundarakkannan, R Kesavamoorthy, N. Dharmarasu, et. al; Raman scattering investigation of surface modification in heat treated BaFC1 [J], Phys. Star. Sol. (a) 2000, 177: 567-573
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