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调制激光作用牙齿组织发生散射形成光子密度波, 而由于光热效应产生热波, 基于一维介质辐射传输漫射近似方程与一维热传导方程建立了调制激光作用牙齿组织半透明混合介质的一维热波数学模型. 利用该模型仿真分析了牙齿龋损特性参数(牙釉质龋损层光吸收系数、散射系数、热扩散系数及龋损深度)对光热辐射动态响应特性的影响与规律. 利用红外探测器(HgCdTe, 212 m)记录808 nm半导体激光激发牙齿组织产生的热波信号, 由锁相放大器计算热波信号的幅值与相位. 通过频率扫描试验获得了牙齿组织的光热动态响应, 利用多参数最佳统计拟合方法得到了牙齿组织特性参数. 结果表明光热辐射测量对牙齿组织不均匀性和龋损特性均具有较高敏感性与特异性.The photon-density wave is generated in tooth tissue due to the scattering induced by modulated laser beams, and furthermore, thermal-wave will form because of photothermal effect. A one-dimensional thermal-wave model for three-layer tooth tissue using modulated laser stimulation is developed based on 1D diffusion approximation of the radiative transfer theory in combination with 1D heat conduction equation. Effects of photothermal properties (i.e. light absorption coefficient, scattering coefficient and thermal diffusivity coefficient), enamel depth and caries depth on the photothermal radiometry (PTR) dynamic responses are investigated based on the 1D thermal wave model coupling with photon-density wave. The PTR amplitude and phase delay (the phase difference between the PTR signal and reference signal) are strongly dependent on the photothermal parameters of the dental enamel caries layers (DECLs). PTR amplitude and phase delay increase with increasing DECL absorption coefficient, scattering coefficient and thermal diffusivity. Additionally, PTR amplitude may also increase due to the larger thickness of caries layer, and the PTR phase peak value is generated at low frequencies. The inhomogeneous photothermal properties of dental enamel healthy layer (DEHL) also have obviously influenced PTR amplitude and phase. Increasing DEHL scattering coefficient leads to the increase of PTR amplitude, but has no apparent effect on the PTR phase. While the PTR phase delay increases with increasing DEHL absorption coefficient. The delay of PTR amplitude and phase is enlarged at the high value of DEHL thermal diffusivity. However, the DEHL layer thickness has no apparent effect on the PTR amplitude and phase.The PTR signal of tooth tissue induced by the 808 nm diode laser is monitored using an infrared detector (HgCdTe, spectral width 2.012.0 m), and the PTR amplitude and phase response are obtained using lock-in amplifier (SR830). Through frequency-scanning experiments of dental tissue, PTR dynamic responses can be measured and employed to characterize the inhomogeneity and caries of the tooth tissue. The photothermal parameters and caries characteristic of the tooth issue can be simultaneously obtained by multi-parameters statistic best-fit.Simulation and experimental results show that the PTR dynamic response has the advantages of high sensitivity and high contrast for inhomogeneity and caries of the tooth tissue.
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Keywords:
- photothermal radiometry /
- tooth tissue /
- optical parameter /
- laser
[1] Shen H, Hu D Y 2013 Stomatology 33 148 (in Chinese) [沈红, 胡德渝 2013 口腔医学 33 148]
[2] Bao W, Ding Z H, Wang C, Mei S T 2013 Acta Phys. sin. 62 114202(in Chinese) [鲍文, 丁志华, 王川, 梅胜涛 2013 62 114202]
[3] Yang Y L, Ding Z. H, Wang K, Wu L, Wu L 2009 Acta Phys. sin. 58 1773(in Chinese) [杨亚良, 丁志华, 王凯, 吴凌, 吴兰 2009 58 1773]
[4] Hriasuna K, Fried D, Darling C L 2008 Proc. J. Biomed. Opt. 13 044011
[5] Meng Z, Yao X T, Lan S F, Yao H, Liu T G, Li Y N, Liang Y, Wang G H 2010 Acta Laser Biology Sinica 19 121 (in Chinese) [孟卓, 姚晓天, 兰寿锋, 姚辉, 刘铁根, 李燕妮, 梁燕, 王冠华 2010 激光生物学报 19 121]
[6] Tang J, Liu L, Li S Z 2009 Acta Optica sin. 29 454 (in Chinese) [唐静, 刘莉, 李颂战 2009 光学学报 29 454]
[7] Mandelis A, Nicolaides L, Feng C, Abrams S H 2000 Proc. SPIE 3916 130
[8] Nicolaides L, Mandelis A, Abrams S H 2000 J. Biomed. Opt. 5 31
[9] Mandelis A 2002 Proc. SPIE 4710 373
[10] Matvienko A, Mandelis A, Jeon R J, Abrams S H 2009 J. Appl. Phys. 105 102022
[11] Jeon R J, Hellen A, Matvienko A, Mandelis A 2008 J. Biomed. Opt. 13 034025
[12] Mandelis A, Feng C 2002 Phys. Rev. E 65 021909
[13] Ishimaru A 1983 J. Opt. Soc. 73 131
[14] Marleen K, Star W M, Pascal R M Storchi 1988 Appl. Opt. 27 1820
[15] Matvienko A, Mandelis A, Hellen A, Jeon R, Abrams S, Amaechi B 2009 Proc. SPIE 7166 8
[16] Hellon A 2010 MS Thesis (Toronto: University of Toronto)
[17] Matvienko A, Mandelis A, Abrams S 2009 Appl. Opt. 48 3197
[18] Brown W S, Dewey W A, Jacob H R 1970 J. Dent. Res. 49 752
[19] Smitch T M, Olejniczak A J, Reid D J 2006 Oral Biol. 51 974
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[1] Shen H, Hu D Y 2013 Stomatology 33 148 (in Chinese) [沈红, 胡德渝 2013 口腔医学 33 148]
[2] Bao W, Ding Z H, Wang C, Mei S T 2013 Acta Phys. sin. 62 114202(in Chinese) [鲍文, 丁志华, 王川, 梅胜涛 2013 62 114202]
[3] Yang Y L, Ding Z. H, Wang K, Wu L, Wu L 2009 Acta Phys. sin. 58 1773(in Chinese) [杨亚良, 丁志华, 王凯, 吴凌, 吴兰 2009 58 1773]
[4] Hriasuna K, Fried D, Darling C L 2008 Proc. J. Biomed. Opt. 13 044011
[5] Meng Z, Yao X T, Lan S F, Yao H, Liu T G, Li Y N, Liang Y, Wang G H 2010 Acta Laser Biology Sinica 19 121 (in Chinese) [孟卓, 姚晓天, 兰寿锋, 姚辉, 刘铁根, 李燕妮, 梁燕, 王冠华 2010 激光生物学报 19 121]
[6] Tang J, Liu L, Li S Z 2009 Acta Optica sin. 29 454 (in Chinese) [唐静, 刘莉, 李颂战 2009 光学学报 29 454]
[7] Mandelis A, Nicolaides L, Feng C, Abrams S H 2000 Proc. SPIE 3916 130
[8] Nicolaides L, Mandelis A, Abrams S H 2000 J. Biomed. Opt. 5 31
[9] Mandelis A 2002 Proc. SPIE 4710 373
[10] Matvienko A, Mandelis A, Jeon R J, Abrams S H 2009 J. Appl. Phys. 105 102022
[11] Jeon R J, Hellen A, Matvienko A, Mandelis A 2008 J. Biomed. Opt. 13 034025
[12] Mandelis A, Feng C 2002 Phys. Rev. E 65 021909
[13] Ishimaru A 1983 J. Opt. Soc. 73 131
[14] Marleen K, Star W M, Pascal R M Storchi 1988 Appl. Opt. 27 1820
[15] Matvienko A, Mandelis A, Hellen A, Jeon R, Abrams S, Amaechi B 2009 Proc. SPIE 7166 8
[16] Hellon A 2010 MS Thesis (Toronto: University of Toronto)
[17] Matvienko A, Mandelis A, Abrams S 2009 Appl. Opt. 48 3197
[18] Brown W S, Dewey W A, Jacob H R 1970 J. Dent. Res. 49 752
[19] Smitch T M, Olejniczak A J, Reid D J 2006 Oral Biol. 51 974
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