Simulation of Optical Response in Oral Tissue - Revision history

Sylc2: /* Measurable Results: Absorbance and Reflectance */

2025-12-11T18:40:09Z

Measurable Results: Absorbance and Reflectance

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	==== Measurable Results: Absorbance and Reflectance ====		==== Measurable Results: Absorbance and Reflectance ====
	~~<span id="Figure_6"></span>~~
	<span id="Figure_7"></span>		<span id="Figure_7"></span>
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Sylc2 at 18:39, 11 December 2025

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Sylc2: /* References */

2025-12-11T18:27:17Z

References

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	<li>Morgan, D. (2024). How does the VELscope work? ''VELscope''. [https://velscope.com/how-does-the-velscope-work/ Link]</li>		<li>Morgan, D. (2024). How does the VELscope work? ''VELscope''. [https://velscope.com/how-does-the-velscope-work/ Link]</li>

	<li>Johnson, E. (~~n.d.~~). VELscope Oral Cancer Detection Device. [https://www.drericjohnson.com/san-clemente-ca/velscope-oral-cancer-detection-device/ Link]</li>		<li>Johnson, E. (2025). VELscope Oral Cancer Detection Device. [https://www.drericjohnson.com/san-clemente-ca/velscope-oral-cancer-detection-device/ Link]</li>
	</ol>		</ol>

Sylc2: /* References */

2025-12-11T18:26:53Z

References

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	<li>Morgan, D. (2024). How does the VELscope work? ''VELscope''. [https://velscope.com/how-does-the-velscope-work/ Link]</li>		<li>Morgan, D. (2024). How does the VELscope work? ''VELscope''. [https://velscope.com/how-does-the-velscope-work/ Link]</li>

			<li>Johnson, E. (n.d.). VELscope Oral Cancer Detection Device. [https://www.drericjohnson.com/san-clemente-ca/velscope-oral-cancer-detection-device/ Link]</li>
	</ol>		</ol>

Sylc2 at 06:16, 11 December 2025

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	== Appendix ==		== Appendix I ==

	Our code can be found at https://github.com/Lisy13012/Simulation-of-Optical-Response-in-Oral-Tissue.		Our code can be found at https://github.com/Lisy13012/Simulation-of-Optical-Response-in-Oral-Tissue.

			== Appendix II ==
			Lise worked on the coefficient plot generations using MC simulations, literature review, and focused on fluence interpretations.
			Sylvia worked on geometry and absorbance/reflectance interpretations, literature review, and understanding MCMatlab.

Sylc2 at 06:11, 11 December 2025

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	==== Measurable Results: Absorbance and Reflectance ====		==== Measurable Results: Absorbance and Reflectance ====
			<span id="Figure_6"></span>
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	The results indicate that Absorbance is consistently higher at 415 nm compared to 450 nm, confirming the simulation correctly models the absorption peak of blood. Notably, Non-Keratinized (NK) tissue exhibits higher absorbance than Keratinized (K) tissue. This is due to the scattering properties of the keratin layer; in K tissue, photons are more likely to be scattered upward and exit the tissue before they can penetrate deep enough to be absorbed, resulting in a lower total absorbance value.		The results (see [[#Figure_6\|Figure 6]]) indicate that Absorbance is consistently higher at 415 nm compared to 450 nm, confirming the simulation correctly models the absorption peak of blood. Notably, Non-Keratinized (NK) tissue exhibits higher absorbance than Keratinized (K) tissue. This is due to the scattering properties of the keratin layer; in K tissue, photons are more likely to be scattered upward and exit the tissue before they can penetrate deep enough to be absorbed, resulting in a lower total absorbance value.

	Reflectance is defined as the total photon energy exiting the tissue surface in the upward direction (measured at the surface), calculated as:		Reflectance is defined as the total photon energy exiting the tissue surface in the upward direction (measured at the surface), calculated as:
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	The reflectance data reveals distinct trends based on wavelength and tissue structure. Reflectance at 415 nm (Blue markers) is consistently lower than at 450 nm (Red markers) for both tissue types, as the strong blood absorption at 415 nm prevents photons from surviving the return trip to the detector. Furthermore, Keratinized tissue (K, Circles) demonstrates significantly higher reflectance than Non-Keratinized tissue (NK, Diamonds). This confirms that the keratin layer acts as a scattering "mirror" or shield: its high scattering coefficient redirects light back toward the surface before it reaches the deep stroma, effectively masking the signal from underlying blood vessels.		The reflectance data (see [[#Figure_7\|Figure 7]]) reveals distinct trends based on wavelength and tissue structure. Reflectance at 415 nm (Blue markers) is consistently lower than at 450 nm (Red markers) for both tissue types, as the strong blood absorption at 415 nm prevents photons from surviving the return trip to the detector. Furthermore, Keratinized tissue (K, Circles) demonstrates significantly higher reflectance than Non-Keratinized tissue (NK, Diamonds). This confirms that the keratin layer acts as a scattering "mirror" or shield: its high scattering coefficient redirects light back toward the surface before it reaches the deep stroma, effectively masking the signal from underlying blood vessels.

	=== Influence of Blood Depth on the Optical Response ===		=== Influence of Blood Depth on the Optical Response ===

Sylc2: /* Measurable Results: Absorbance and Reflectance */

2025-12-11T06:10:36Z

Measurable Results: Absorbance and Reflectance

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	==== Measurable Results: Absorbance and Reflectance ====		==== Measurable Results: Absorbance and Reflectance ====
			<span id="Figure_9"></span>
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Sylc2: /* Measurable Results: Absorbance and Reflectance */

2025-12-11T06:10:08Z

Measurable Results: Absorbance and Reflectance

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	To quantify the impact of vascular depth on the optical signal, we analyzed the total absorbance and reflectance as a function of the blood carpet's position (varying from 200 μm to 800 μm).		To quantify the impact of vascular depth on the optical signal, we analyzed the total absorbance and reflectance as a function of the blood carpet's position (varying from 200 μm to 800 μm).

	Absorbance is defined here as the total amount of light energy lost (absorbed) inside the tissue volume. The graph above displays Absorbance vs. Vessel Depth, illustrating a trend similar to exponential decay. As the blood vessel is positioned deeper within the tissue, the total absorbance decreases. This occurs because the excitation light is attenuated by the overlying tissue layers before it reaches the blood; fewer photons reach the deep vessels, resulting in less energy absorption. The curve decays until it asymptotes to a final "control value," representing the baseline absorbance of bloodless tissue. The rate of this decay changes noticeably depending on whether the vessel is located in the epithelium or the stroma, reflecting the different attenuation properties of these tissue layers. Absorbance is consistently higher for 415 nm wavelength compared to 450 nm, confirming the higher sensitivity of the 415 nm wavelength to hemoglobin. Absorbance is higher in Non-Keratinized (NK) tissue than in Keratinized (K) tissue. In K-tissue, the highly scattering superficial layer reflects a significant portion of photons back out of the tissue before they can penetrate deep enough to be absorbed by the blood, effectively "shielding" the signal.		Absorbance is defined here as the total amount of light energy lost (absorbed) inside the tissue volume. The graph above (see [[#Figure_9\|Figure 9]]) displays Absorbance vs. Vessel Depth, illustrating a trend similar to exponential decay. As the blood vessel is positioned deeper within the tissue, the total absorbance decreases. This occurs because the excitation light is attenuated by the overlying tissue layers before it reaches the blood; fewer photons reach the deep vessels, resulting in less energy absorption. The curve decays until it asymptotes to a final "control value," representing the baseline absorbance of bloodless tissue. The rate of this decay changes noticeably depending on whether the vessel is located in the epithelium or the stroma, reflecting the different attenuation properties of these tissue layers. Absorbance is consistently higher for 415 nm wavelength compared to 450 nm, confirming the higher sensitivity of the 415 nm wavelength to hemoglobin. Absorbance is higher in Non-Keratinized (NK) tissue than in Keratinized (K) tissue. In K-tissue, the highly scattering superficial layer reflects a significant portion of photons back out of the tissue before they can penetrate deep enough to be absorbed by the blood, effectively "shielding" the signal.

	Reflectance is defined as the total photon energy exiting the tissue surface upward (i.e., the light that comes back out to the detector). It is measured at the surface. The graph demonstrates that Reflectance is consistently higher in Keratinized (K) tissue compared to Non-Keratinized (NK) tissue. This is driven by the high scattering coefficient (<math>\mu_s</math>) of the keratin layer, which acts like a diffusive mirror, redirecting photons back toward the surface. Reflectance generally follows an inverse trend to absorbance; where absorbance is high (e.g., shallow vessels in NK tissue), reflectance is low because the energy is trapped. As the vessel moves deeper and absorbs less light, the total reflectance recovers toward the baseline value.		Reflectance is defined as the total photon energy exiting the tissue surface upward (i.e., the light that comes back out to the detector). It is measured at the surface. The graph (see [[#Figure_10\|Figure 10]]) demonstrates that Reflectance is consistently higher in Keratinized (K) tissue compared to Non-Keratinized (NK) tissue. This is driven by the high scattering coefficient (<math>\mu_s</math>) of the keratin layer, which acts like a diffusive mirror, redirecting photons back toward the surface. Reflectance generally follows an inverse trend to absorbance; where absorbance is high (e.g., shallow vessels in NK tissue), reflectance is low because the energy is trapped. As the vessel moves deeper and absorbs less light, the total reflectance recovers toward the baseline value.

	== Discussion and Conclusions ==		== Discussion and Conclusions ==

Sylc2: /* Five Layer Model and Geometry */

2025-12-11T06:09:28Z

Five Layer Model and Geometry

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	In addition to the stratified epithelial layers, our simulation strategy evolved to address the spatial distribution of blood within the stroma. Initially, we considered modeling a single large blood vessel to represent blood spots. However, this approach proved unrealistic for capturing the optical effects of the diffuse microvasculature characteristic of the oral tissue. To address this limitation while maintaining a manageable simulation trade-off, we developed a "blood carpet" model.		In addition to the stratified epithelial layers, our simulation strategy evolved to address the spatial distribution of blood within the stroma. Initially, we considered modeling a single large blood vessel to represent blood spots. However, this approach proved unrealistic for capturing the optical effects of the diffuse microvasculature characteristic of the oral tissue. To address this limitation while maintaining a manageable simulation trade-off, we developed a "blood carpet" model.

	The blood carpet represents a continuous, dense layer of small blood vessels rather than a single discrete object. This configuration allows us to simulate the optical properties of a highly perfused vascular bed within the 3D geometry. This setup enables us to systematically vary the depth of the blood layer to determine how the "dark spot" signal changes as vessels are located deeper in the tissue. We generated several versions of the geometry where this blood carpet is positioned at specific depths ranging from the basal epithelium down to the deep stroma. ([[#Figure_4\|Figure 4]]) below illustrates this progression, showing the blood carpet at depths of 200, 300, 400, 500, 600, and 800 μm.		The blood carpet represents a continuous, dense layer of small blood vessels rather than a single discrete object. This configuration allows us to simulate the optical properties of a highly perfused vascular bed within the 3D geometry. This setup enables us to systematically vary the depth of the blood layer to determine how the "dark spot" signal changes as vessels are located deeper in the tissue. We generated several versions of the geometry where this blood carpet is positioned at specific depths ranging from the basal epithelium down to the deep stroma. [[#Figure_4\|Figure 4]] below illustrates this progression, showing the blood carpet at depths of 200, 300, 400, 500, 600, and 800 μm.

	<span id="Figure_4"></span>		<span id="Figure_4"></span>

Sylc2: /* Five Layer Model and Geometry */

2025-12-11T06:09:12Z

Five Layer Model and Geometry

← Older revision		Revision as of 06:09, 11 December 2025
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	In addition to the stratified epithelial layers, our simulation strategy evolved to address the spatial distribution of blood within the stroma. Initially, we considered modeling a single large blood vessel to represent blood spots. However, this approach proved unrealistic for capturing the optical effects of the diffuse microvasculature characteristic of the oral tissue. To address this limitation while maintaining a manageable simulation trade-off, we developed a "blood carpet" model.		In addition to the stratified epithelial layers, our simulation strategy evolved to address the spatial distribution of blood within the stroma. Initially, we considered modeling a single large blood vessel to represent blood spots. However, this approach proved unrealistic for capturing the optical effects of the diffuse microvasculature characteristic of the oral tissue. To address this limitation while maintaining a manageable simulation trade-off, we developed a "blood carpet" model.

	The blood carpet represents a continuous, dense layer of small blood vessels rather than a single discrete object. This configuration allows us to simulate the optical properties of a highly perfused vascular bed within the 3D geometry. This setup enables us to systematically vary the depth of the blood layer to determine how the "dark spot" signal changes as vessels are located deeper in the tissue. We generated several versions of the geometry where this blood carpet is positioned at specific depths ranging from the basal epithelium down to the deep stroma. ~~The figure~~ below illustrates this progression, showing the blood carpet at depths of 200, 300, 400, 500, 600, and 800 μm.		The blood carpet represents a continuous, dense layer of small blood vessels rather than a single discrete object. This configuration allows us to simulate the optical properties of a highly perfused vascular bed within the 3D geometry. This setup enables us to systematically vary the depth of the blood layer to determine how the "dark spot" signal changes as vessels are located deeper in the tissue. We generated several versions of the geometry where this blood carpet is positioned at specific depths ranging from the basal epithelium down to the deep stroma. ([[#Figure_4\|Figure 4]]) below illustrates this progression, showing the blood carpet at depths of 200, 300, 400, 500, 600, and 800 μm.

			<span id="Figure_4"></span>
	<gallery mode="packed" heights="150px" >		<gallery mode="packed" heights="150px" >
	File:Bloodcarpet200arrow.png\|Depth: 200 μm		File:Bloodcarpet200arrow.png\|Depth: 200 μm