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The measured (symbols) and calibrated (lines) reflectance spectra for a set of four colored diffuse reflectance standards: red ( • ), yellow (□), green (▴), and blue (⋄). Correction for the singlebeam substitution error brought the measured reflectance values to within 0.01 of the calibrated reflectance specified by the supplier.

The measured (symbols) and calibrated (lines) reflectance spectra for a set of four colored diffuse reflectance standards: red ( • ), yellow (□), green (▴), and blue (⋄). Correction for the singlebeam substitution error brought the measured reflectance values to within 0.01 of the calibrated reflectance specified by the supplier.

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Article
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The measurement of changes in blood volume in tissue is important for monitoring the effects of a wide range of therapeutic interventions, from radiation therapy to skin-flap transplants. Many systems available for purchase are either expensive or difficult to use, limiting their utility in the clinical setting. A low-cost system, capable of measur...

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... applied to the modified total diffuse reflectance, resulting in a corrected total diffuse reflectance (R m ). A set of colored diffuse reflectance standards (CSS-04-010, Labsphere, North Sutton, New Hampshire) were measured and, following correction, the measured reflectance was within 0.01 of the calibrated reflectance specified by the supplier (Fig. ...

Citations

... En este trabajo se utilizó la aproximación propuesta por Glennie et Al. [323] para determinar el Indice del Eritema de Dawson a partir de mediciones de DRS. Este parámetro se calcula como elárea bajo la curva del negativo del logaritmo base 10 del espectro de la reflectancia difusa (conocido como la absorbancia aparente y expresado por la ecuación 4.6 en un rango de 650 − 700nm, y de igual forma que para el indice de melanina, descartando las contribuciones de la deoxy-Hb y la oxy-Hb. ...
... However, visual assessment is far from ideal, since it is subjective and strongly dependent on observer experience and human factors including visual acuity. Two assessment techniques, Diffuse reflectance spectroscopy (DRS) [30][31][32] and digital imaging [33][34][35] were studied as objective alternatives to VA. Yet, both were found unsatisfactory by clinicians. ...
Article
Skin cancer (SC) is a widely spread disease in the USA, Canada, and Australia. Skin cancer patients are mostly of advanced age and therefore more likely to be treated with radiation therapy as many are comorbid and not surgical candidates. However, radiation therapy has side effects, which may range from skin erythema to skin necrosis. As erythema is the early evidence of exposure to radiation, monitoring erythema is important to prevent more severe reactions. Visual assessment (VA) is the gold standard for evaluating erythema. Nevertheless, VA is not ideal, since it depends on the observer’s experience and skills. Digital photography and hyperspectral imaging (HSI) are optical techniques that provide an opportunity for objective assessment of erythema. Erythema indices were computed from the spectral data using Dawson’s technique. The Dawson relative erythema index proved to be highly correlated (97.1%) with clinical visual assessment scores. In addition, on the 7th session of radiation therapy, the relative erythema index differentiates with 99% significance between irradiated and non-radiated skin regions. In this study, HSI is compared to digital photography for skin erythema statistical classification.
... Each EMW band has an exposure threshold or 'minimal erythema dose' (MED) [6]; if reached, skin erythema is directly induced [7]. In addition to EMW exposure, physical pressure [8], skin ulceration [9,10], application of cosmetic and medical topical agents, and electrical stimulation [11][12][13][14] are all external stimuli of skin erythema. Over and above, burns induce erythema around resultant scars [15]. ...
... For instance, a recent study proved that IS-DRS system can be built with low costs while being efficient and simple to construct as shown in Fig. 3 [14]. The same setup was used in a clinical study to detect the temporal development of skin erythema via computing the erythema index. ...
... The study displayed the computed erythema indices based on the measurement of the daily skin diffuse reflectance in cancer patients. Based on the computed erythema index, DRS was able to detect the patients' skin color change earlier than visual assessment, however, both techniques were done synchronously [14]. In addition, the acquired DRS data were able to quantify skin erythema via estimating the apparent concentrations of skin chromophores during radiation treatment [14]. ...
Article
Abstract Background Skin erythema may present due to many causes. One of the common causes is prolonged exposure to sun rays. Other than sun exposure, skin erythema is an accompanying sign of dermatological diseases such as acne, psoriasis, melasma, post inflammatory hyperpigmentation, fever, as well as exposure to specific electromagnetic wave bands. Methods Quantifying skin erythema in patients enables the dermatologist to assess the patient’s skin health. Therefore, quantitative assessment of skin erythema was the target of several studies. The clinical standard for erythema evaluation is visual assessment. However, the former standard has some imperfections. For instance, it is subjective, and unqualified for precise color information exchange. To overcome these shortcomings, the past three decades witnessed various methodologies that aimed to achieve erythema objective assessment, such as diffuse reflectance spectroscopy (DRS), and both optical and non-optical systems. Discussion This review article revises the studies published in the past three decades where the performance, the mathematical tactics for computation, and the limited capabilities of erythema assessment techniques for cutaneous diseases are discussed. In particular, the current achievements and limitations of the current techniques in erythema assessment are presented. Conclusion The profits and development trends of optical and non-optical methods are displayed to provide the researcher with awareness into the present technological advances and its potential for dermatological diseases research. Keywords Skin pigments; Erythema assessment; Dermatological diseases; Skin inflammation; Optical diagnosis
... treatment plan, unless attentively monitored and precisely addressed (13). Erythema is not only accompanying radiation therapy treatment, but also photodynamic therapy and plastic surgery. ...
... This interest fueled the innovation of precise techniques for quantifying erythema. From most to least complex, the techniques are: spectroscopy, colorimetry/ photography, and visual assessment (VA) (13). VA is still the current gold standard for erythema assessment in dermatology clinics (14,15). ...
Conference Paper
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Surveillance and assessment of radiation-induced erythema is an important aspect of managing skin toxicity in radiation therapy treated patients. Upon receiving the early fractions of radiation, an inflammatory response and vascular dilation takes place due to damage of basal cells in the skin’s epidermal layer. This process of skin reddening known as erythema. The gold standard used for assessing and grading erythema is visual assessment (VA) by an experienced clinician/ radiotherapist using toxicity scoring tools. This method is limited by the assessor’s experience, vision acuity, and the subjectivity of qualitative scores. An alternative optical technique to VA, is diffuse reflectance spectroscopy (DRS). A comparison between both techniques performance in detecting radiation therapy-induced erythema is demonstrated in this pilot study. The results evidenced that DRS is capable of detecting skin erythema before an expert eye could do so.
... For that reason, melanin effect needs to be compensated in erythema index computation. For melanin correction factor, reflectance data at two wavelengths (650&700 nm) is used to compute Dawson melanin index (DMI) [40]. The former wavelengths were selected because melanin spectral absorbance is proportional to its concentration at these two spectral points, as well as the low absorbance of the hemoglobin in this spectral region [39]. ...
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Skin cancer (SC) is a widely spread type of cancer in USA, Canada, and Australia. Patients, in the senior age, of skin cancer is usually referred to radiation therapy, rather than surgery due to old age complications, for treatment. However, radiation therapy induces side effects that may vary between tissue necrosis down to skin erythema. As erythema is the primary evidence of skin health perturbation due to radiation exposure, it needs to be precisely assessed. Visual assessment (VA) is the gold standard for erythema evaluation. Nevertheless, VA is anything but ideal, due to being dependent on experience and varying human sensations. Hyperspectral imaging (HSI), far from human dependency, is an optical technique that provides an opportunity for objective investigation of erythema. HSI spectral data permitted the computation of erythema indices using Dawson's technique. Dawson relative erythema index proved to be highly correlated (97.1%) to clinically visual score in monitoring skin erythema. In addition, on the 7 th session of radiation therapy, relative erythema index differentiates with 99% significance between irradiated and non-radiated skin regions. In this study, HSI is compared to digital photography for skin erythema statistical classification.
... An intriguing example of MED is the transient flush erythema which takes place rapidly in people with fair skin, in the summer upon exposure to sunlight [10]. In addition to EMW exposure, physical pressure [11], skin ulceration [12], [13], application of cosmetic/medical topical agents, and electrical stimulation [14]- [17] are all external stimuli of skin erythema. Over and above, burns induce erythema around resultant scars [18]. ...
... Figure 5 displays the computed erythema indices in the study, based on the measurement of the daily skin diffuse reflectances in cancer patients. Based on the computed erythema index, DRS was able to detect the patients' skin color change earlier than visual assessment, however, both techniques were done synchronously [17]. Over and above, the acquired DRS data were able to quantify skin erythema via estimating the apparent concentrations of skin chromophores during radiation treatment [17]. ...
... Based on the computed erythema index, DRS was able to detect the patients' skin color change earlier than visual assessment, however, both techniques were done synchronously [17]. Over and above, the acquired DRS data were able to quantify skin erythema via estimating the apparent concentrations of skin chromophores during radiation treatment [17]. In sum, the simple and affordable IS-DRS system succeeded to properly detect and precisely quantify radiation dermatitis during cancer treatment before visual detection by radiotherapists was possible. ...
... Diffuse reflectance spectroscopy (DRS) is a non-invasive method which can be used to quantify volumetric total hemoglobin concentration (THC), tissue oxygen saturation (StO 2 ), and tissue scattering at or within accessible tissue sites [1][2][3][4][5][6][7][8][9][10]. This technique has been adapted for studies of tumor perfusion and response to therapy, since THC and StO 2 can be used to differentiate therapeutic responders from non-responders over the course of treatment [11][12][13]. ...
Article
Diffuse reflectance spectroscopy (DRS) has been used in murine studies to quantify tumor perfusion and therapeutic response. These studies frequently use inhaled isoflurane anesthesia, which depresses the respiration rate and results in the desaturation of arterial oxygen saturation, potentially affecting tissue physiological parameters. However, there have been no controlled studies quantifying the effect of isoflurane anesthesia on DRS-derived physiological parameters of murine tissue. The goal of this study was to perform DRS on Balb/c mouse (n = 10) tissue under various anesthesia conditions to quantify effects on tissue physiological parameters, including total hemoglobin concentration, tissue oxygen saturation, oxyhemoglobin and reduced scattering coefficient. Two independent variables were manipulated including metabolic gas type (pure oxygen vs. medical air) and isoflurane concentration (1.5 to 4.0%). The 1.5% isoflurane and 1 L/min oxygen condition most closely mimicked a no-anesthesia condition with oxyhemoglobin concentration within 89% ± 19% of control. The time-dependent effects of isoflurane anesthesia were tested, revealing that anesthetic induction with 4.0% isoflurane can affect DRS-derived physiological parameters up to 20 minutes post-induction. Finally, spectroscopy with and without isoflurane anesthesia was compared for colon tumor Balb/c-CT26 allografts (n = 5) as a representative model of subcutaneous murine tumor allografts. Overall, isoflurane anesthesia yielded experimentally-induced depressed oxyhemoglobin, and this depression was both concentration and time dependent. Investigators should understand the dynamic effects of isoflurane on tissue physiological parameters measured by DRS. These results may guide investigators in eliminating, limiting, or managing anesthesia-induced physiological changes in DRS studies in mouse models. © 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement.
... Until now(?), visual assessment by a dermatologist [3], [4]is the gold standard for diagnosising and evaluating the treatment of skin diseases [1], [2],. However, visual assessment was criticized in many studies to be subjective, qualitative, temporally inconsistent, and invasive [5]- [10]. ...
... Within optical techniques, there are two main approaches for skin assessment: diffuse reflectance spectroscopic (DRS) measurements and color imaging. The spectroscopic-based-approach is well-known for detecting the spectral signature of the skin's signs with highly precise, inexpensive equipment [4]. Hence, it aids the dermatologist in differentiating between visibly similar skin conditions. ...
Conference Paper
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The incessant innovations of hyperspectral imaging (HSI) and data mining algorithms create necessity for developing reliable means of assessment and comparison. In medical applications of HSI, for instance, one of such means is tissue-equivalent phantoms. These phantoms are designed to mimic the spectral behavior of real living tissues. In this work, gel-based-phantoms were prepared with adjusted ingredients. The gel phantom's ingredients include India ink and Intralipid to provide absorption and scattering, respectively. Unlike visual assessment and photography, HSI was successful in identifying the various phantoms based on their spectral signature. In conclusion, we introduce a simple method of evaluating the performance of newly developed optical imaging techniques including HSI via affordable, inexpensive, and easy-to-make phantoms.
... The TRF spectroscopy measures fluorescence intensity and lifetime of fluorophores, providing information on biological composition of tissue [16,19,20]. DRS reveal optical properties that relay information on absorber concentration as well as scattering size, structure, and density of cells [17,21,22]. Although both techniques have been used separately to classify tissue types, the integration of both modalities allows the yield of higher sensitivity and specificity than each modality alone. ...
... The reduced scattering coefficient was also shown to increase as a result of increased nuclear size, DNA content and hyperchromasia [39]. Significantly higher reduced scattering coefficient was observed in tumor (22.162 cm À1 at 545 nm and 21.273 cm À1 at 575 nm) compared to the normal breast tissue (18.571 cm À1 at 545 nm and 17.826 cm À1 at 575 nm) as per Table 11 and Figure 8, which was consistent with findings from previous studies [3,22,40,41]. Zhu et al. [6] noted that the reduced scatter coefficient was inversely correlated to the amount of adipose tissue present as well as the patient body mass index (BMI). The observed increase in the reduced scatter coefficient observed in this study could be linked to increased fibro-connective and glandular tissue content and thus cancer development. ...
Article
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Purpose: One of the major problems in breast cancer surgery is defining surgical margins and establishing complete tumor excision within a single surgical procedure. The goal of this work is to establish instrumentation that can differentiate between tumor and normal breast tissue with the potential to be implemented in vivo during a surgical procedure. Methods: A time-resolved fluorescence and reflectance spectroscopy (tr-FRS) system is used to measure fluorescence intensity and lifetime as well as collect diffuse reflectance (DR) of breast tissue, which can subsequently be used to extract optical properties (absorption and reduced scatter coefficient) of the tissue. The tr-FRS data obtained from patients with Invasive Ductal Carcinoma (IDC) whom have undergone lumpectomy and mastectomy surgeries is presented. A preliminary study was conducted to determine the validity of using banked pre-frozen breast tissue samples to study the fluorescence response and optical properties. Once the validity was established, the tr-FRS system was used on a data-set of 40 pre-frozen matched pair cases to differentiate between tumor and normal breast tissue. All measurements have been conducted on excised normal and tumor breast samples post surgery. Results: Our results showed the process of freezing and thawing did not cause any significant differences between fresh and pre-frozen normal or tumor breast tissue. The tr-FRS optical data obtained from 40 banked matched pairs showed significant differences between normal and tumor breast tissue. Conclusion: The work detailed in the main study showed the tr-FRS system has the potential to differentiate malignant from normal breast tissue in women undergoing surgery for known invasive ductal carcinoma. With further work, this successful outcome may result in the development of an accurate intraoperative real-time margin assessment system. Lasers Surg. Med. 50:236-245, 2018. © 2018 Wiley Periodicals, Inc.
... One depth sensitive technique that has demonstrated diagnostic efficacy is diffuse reflectance spectroscopy (DRS), a well-established method capable of non-invasively quantifying volume-averaged tissue optical parameters using simple probe designs [33][34][35][36][37][38][39] . Raw DRS data is given in terms of reflectance, that is, the percentage of light recovered from a detection fiber to light delivered by a source fiber. ...
... Several in vivo DRS studies have extracted other clinically relevant optical parameters including blood volume fraction, hemoglobin concentration, oxygen saturation, mean blood vessel diameter, nicotinamide adenine dinucleotide (NADH) concentration, and tissue thickness [34][35][36][37][48][49][50][51][52] . Furthermore, DRS is an appealing non-invasive screening technique because it is sensitive to optical changes beneath the apical tissue layer [33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52] . However, a drawback of DRS is inability to spatially resolve tissue architecture. ...
... Spectra were converted to absolute reflectance values by calibrating with a Spectralon ® 20% diffuse reflectance standard (SRS-20-010, Labsphere, USA) which was spectrally flat between 200-2600 nm. All spectra were corrected for background noise 33,34,40,47,49 . After acquiring absolute reflectance spectra at a resolution of 0.35 nm, the LUTs relating reflectance (R) to μ s ′ and μ a were generated using MATLAB. ...
Article
Full-text available
Intraepithelial dysplasia of the oral mucosa typically originates in the proliferative cell layer at the basement membrane and extends to the upper epithelial layers as the disease progresses. Detection of malignancies typically occurs upon visual inspection by non-specialists at a late-stage. In this manuscript, we validate a quantitative hybrid imaging and spectroscopy microendoscope to monitor dysplastic progression within the oral cavity microenvironment in a phantom and pre-clinical study. We use an empirical model to quantify optical properties and sampling depth from sub-diffuse reflectance spectra (450–750 nm) at two source-detector separations (374 and 730 μm). Average errors in recovering reduced scattering (5–26 cm−1) and absorption coefficients (0–10 cm−1) in hemoglobin-based phantoms were approximately 2% and 6%, respectively. Next, a 300 μm-thick phantom tumor model was used to validate the probe’s ability to monitor progression of a proliferating optical heterogeneity. Finally, the technique was demonstrated on 13 healthy volunteers and volume-averaged optical coefficients, scattering exponent, hemoglobin concentration, oxygen saturation, and sampling depth are presented alongside a high-resolution microendoscopy image of oral mucosa from one volunteer. This multimodal microendoscopy approach encompasses both structural and spectroscopic reporters of perfusion within the tissue microenvironment and can potentially be used to monitor tumor response to therapy.