In collaboration with the University of Edinburgh, the University of Nottingham, the University of Southampton and the Engineering and Physical Sciences Research Council. InlightenUs is a medical imaging project that brings together a team of interdisciplinary scientists to develop treatment techniques/ options that fulfil the needs of healthcare in 2050.

The research will look to develop hand-held devices that can be used in GP Surgeries and on hospital wards which enable doctors and nurses to see inside a patient’s body and provide fast diagnoses and considerable savings for the NHS.

One of the projects being carried out is a review of the effect of skin color on optical properties and the implication of variation on optical medical technologies. In light of COVID-19 highlighted the importance of understanding of the interaction of light with different skin types, e.g., pulse oximetry (PO) unreliably determined oxygen saturation levels in people from Black and ethnic minority backgrounds. This project can hold significant impacts on the representation of medical devices and consequently its accuracy and reliability when utilised by all patients regardless of race and ethnicity.

A scale used to identify skin cancer risk by measuring the amount of melanin in the skin. The general consensus pushed by the Fitzpatrick Scale is that those with lower levels of melanin (types I and II) are at a higher risk of skin cancer. Most studies categorise the scale into Types: I, II, III, IV, V, VI.

Effect of skin color on optical properties and the implications for medical optical technologies: a review

Kerry Setchfield, Alistair Gorman, A. Hamish R. W. Simpson, Michael G. Somekh, Amanda J. Wright

Relevance and utility of the in-vivo and ex-vivo optical properties of the skin reported in the literature: a review

Kerry Setchfield, Alistair Gorman, A Hamish R W Simpson, Michael G Somekh, Amanda J Wright

EPSRC IN-LIGHTEN-US

Medical wearable devices, particularly those using photoplethysmography (PPG), are used to measure vital signs like heart rate, blood pressure, and oxygen levels. PPG employs light to monitor blood flow either in transmission (from opposite side of detection) or reflection (from same side).

Current PPG, especially pulse oximetry (PO), estimates oxygen saturation by comparing light absorption in oxygenated versus deoxygenated blood. However, skin pigmentation affects accuracy, particularly in darker skin tones, leading to overestimation of oxygen levels, which was evident during the COVID-19 pandemic, posing risks for undetected low oxygen levels, especially in Black patients.

The depth penetration of light in darker skin tones further contributes to this bias. There's concern that racial bias also affects other wearable healthcare devices, potentially worsening healthcare disparities. While some studies suggest no effect of skin color on device accuracy, others criticize these findings for small sample sizes and inaccurate skin color determination, indicating a need for further research and awareness in addressing healthcare inequalities.

Item descrPhotodynamic Therapy (PDT) is a treatment method employing light-sensitive drugs to destroy abnormal cells in various conditions such as skin diseases, eye disorders, and certain cancers. Effective PDT relies on understanding how light propagates through tissues, influenced by absorption and scattering coefficients.

PDT research predominantly involves light-skinned patients, there's a call for studies to include a broader range of skin types to accurately assess its efficacy and address disparities in skin cancer diagnosis and survival rates among different populations.

Different tissues absorb light differently, with substances like hemoglobin and melanin being strong absorbers. PDT can be applied superficially, invasively, or within cavities depending on the condition being treated. The process involves activating a photosensitive drug with light and oxygen to produce reactive oxygen intermediates that damage cells irreversibly. Selectivity in treatment is influenced by drug uptake, metabolism, and light penetration, which can be affected by tissue optical properties and Fitzpatrick Skin Type (FST). Inflammatory hyperpigmentation is a common side effect, particularly in darker skin types.

PDT utilizes various wavelengths, with blue light for optimal absorbance and longer wavelengths for better tissue penetration. Common photosensitizing drugs include aminolevulinic acid (ALA) and methyl aminolevulinate (MAL), activated by specific light wavelengths. PDT efficacy and adverse effects vary based on individual skin properties, necessitating personalized treatment approaches.iption

Optical imaging techniques are valuable for reducing patients' exposure to ionizing radiation, making them suitable for repeated use in monitoring disease progression and treatment outcomes. Among these techniques, Optical Coherence Tomography (OCT) stands out for its ability to provide high-resolution, noninvasive three-dimensional images of tissues. OCT utilizes interferometry to detect back-reflected light from biological tissues, enabling imaging at depths of up to 2 mm with resolution smaller than 10 μm.

OCT finds wide application in various medical fields, including ophthalmology, cardiology, gastroenterology, and dermatology. In dermatology, OCT is particularly useful for diagnosing skin disorders like basal cell carcinomas (BCCs) and monitoring therapy for conditions such as scleroderma and psoriasis. However, its accuracy in diagnosing malignant melanomas is limited. While OCT is effective in imaging skin layers and structures, its performance can be affected by factors like skin color and melanin absorption.

Studies on the impact of skin color on OCT imaging are limited, but there are indications that imaging quality may be slightly lower in individuals with darker skin due to melanin absorption, although the differences may not be significant across all skin types. Further research is needed to understand the effect of skin type on OCT imaging comprehensively. Despite using longer wavelengths that are presumed to be unaffected by melanin absorption, the influence of skin color on OCT imaging remains an area requiring more investigation.