Optical changes of porcine brain tissue after thermal coagulation

Hans-Joachim Schwarzmaier M.D.; Thomas Goldbach; Ilya V. Yaroslavsky; Frank Ulrich; Martin Bettag; Thomas Kahn M.D.; Raimund Kaufmann

doi:10.1117/12.209912

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22 May 1995 Optical changes of porcine brain tissue after thermal coagulation

Hans-Joachim Schwarzmaier M.D., Thomas Goldbach, Ilya V. Yaroslavsky, Frank Ulrich, Martin Bettag, Thomas Kahn M.D., Raimund Kaufmann

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Proceedings Volume 2391, Laser-Tissue Interaction VI; (1995) https://doi.org/10.1117/12.209912
Event: Photonics West '95, 1995, San Jose, CA, United States

Abstract

Porcine brain tissue is a model for human brain structures in laser induced thermo-therapy. However, its optical properties including possible heat-related changes were basically unknown so far. To simulate laser coagulation, 12 specimens (6 grey and 6 white matter) were heated in a saline bath (80°C, 2 hours) and compared to 11 untreated samples (5 grey and 6 white matter). The optical constants were obtained from transmission (total and collimated) and reflection (diffuse) measurements using the inverse Monte-Carlo method. The absorption coefficient ((mu) _a) of untreated grey substance decreased from 0.35 +/- 0.06/mm (340 nm) to 0.03 +/- 0.02/mm (800 nm). The scattering coefficient ((mu) _s) varied between 20.42 +/- 3.65/mm (340 nm) and 6.85 +/- 2.07/mm (800 nm). The anisotropy factor (g) increased from 0.848 +/- 0.013 (340 nm) to 0.889 +/- 0.009 (800 nm). Coagulation increased (mu) _a up to a factor of 2 (340-540 nm; p < 0.05), and (mu) _s by a factor up to 3 (340-800 nm, all data p < 0.001) while g was decreased up to 18% (340-560 nm; p < 0.05). White substance exhibited a (mu) _a between 0.24 +/- 0.07/mm (340 nm) and 0.04 +/- 0.02/mm (800 nm) while (mu) _s varied between 26.72 +/- 9.10/mm (340 nm) and 21.78 +/- 3.88/mm (800 nm). The g-value increased from 0.561 +/- 0.180 (340 nm) to 0.834 +/- 0.068 (800 nm). Coagulation increased (mu) _a by a factor up to 2 (340-800 nm; all data p < 0.05) while (mu) _s and g remained unchanged. Thermal denaturation changes the absorption and scattering properties of porcine brain significantly.

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Hans-Joachim Schwarzmaier M.D., Thomas Goldbach, Ilya V. Yaroslavsky, Frank Ulrich, Martin Bettag, Thomas Kahn M.D., and Raimund Kaufmann "Optical changes of porcine brain tissue after thermal coagulation", Proc. SPIE 2391, Laser-Tissue Interaction VI, (22 May 1995); https://doi.org/10.1117/12.209912

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