Article

Hyperspectral Imaging Assessment for Radiotherapy Induced Skin-Erythema: Pilot study

Authors:
  • Juravinski Cancer Centre
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Abstract

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.

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The ability to monitor changes in the concentration of hemoglobin in the blood of the skin in real time is a key component to personalized patient care. Since hemoglobin has a unique absorption spectrum in the visible light range, diffuse reflectance spectroscopy is the most common approach. Although the collection of the diffuse reflectance spectrum with an integrating sphere (IS) has several calibration challenges, this collection method is sufficiently user-friendly that it may be worth overcoming the initial difficulty. Once the spectrum is obtained, it is commonly interpreted with a log-inverse-reflectance (LIR) or "absorbance" analysis that can only accurately monitor changes in the hemoglobin concentration when there are no changes to the nonhemoglobin chromophore concentrations which is not always the case. We address the difficulties associated with collection of the diffuse reflectance spectrum with an IS and propose a model capable of retrieving relative changes in hemoglobin concentration from the visible light spectrum. The model is capable of accounting for concentration changes in the nonhemoglobin chromophores and is first characterized with theoretical spectra and liquid phantoms. The model is then used in comparison with a common LIR analysis on temporal measurements from blanched and reddened human skin. (C) 2015 Society of Photo-Optical Instrumentation Engineers (SPIE)
Article
AimTo assess the effectiveness of conventionally fractionated radiotherapy for local control and cosmesis in elderly patients (age 70 years or older) with non-melanoma skin cancer of the head.MethodsA retrospective review of 15 patients undergoing definitive radiation (11 patients) or postoperative radiation (4 patients) for squamous cell carcinoma (9 patients) and basal cell carcinoma (6 patients) of the head was undertaken. At each follow-up visit, a radiation oncology resident and/or medical student was requested to examine the patient's head and neck, and determine the initial location of the cancer without reviewing their medical record.ResultsNo patient developed a loco-regional recurrence. The residents and medical students were unable to determine the initial location of the cancer because of the skin normalcy.Conclusion Conventionally fractionated radiotherapy is effective for local control and provides excellent cosmesis for elderly patients with skin cancer of the head. Geriatr Gerontol Int 2014; ●●: ●●–●●.
Article
Hyperspectral imaging is an optical method that provides a large amount of information about the investigated object. Its medical applications are reviewed in this article, including tumor delimitation and identification, assessing tissue perfusion and its pathological conditions (including some complications like diabetic foot ulceration), making accurate surgical decisions, evaluating the health of dental structures, etc. Many of the articles show very promising results that required brief comments by the authors. It is clear that choosing the appropriate hyperspectral imaging system for each medical field, together with the most reliable hyperspectral image processing methods, are the main goals of future studies, before hyperspectral imaging becomes a widely applicable evaluation method in medicine. The authors try to answer some questions on this topic and set up some directions for future research.
Article
Abstract Noninvasive determinations of the amount of cutaneous blood in the superficial plexus are made from skin reflectance measurements after exposure of human skin to UV radiation. The approach considers the skin as consisting of multiple optically distinct layers, and utilizes a previously experimentally verified optical model that relates the optical properties of these skin layers to skin reflectance. When the UV erythema is concurrently graded by visual inspection, our results show that each subjective grade corresponds to a broad range of values of cutaneous blood, and a wide overlap in blood volumes occurs between different grades. The amount of cutaneous blood increases with the UV dose, and follows a sigmoid threshold relationship. Erythema fades with time, but the rate of decrease in cutaneous blood is volume dependent. The sharpest decrease occurs when the amount of cutaneous blood is within 1.5 - 2.5 times the pre-radiation volume. Slower decrease occurs when the volume of blood is outside of this range.
Article
In this work we address the subspace clustering problem. Given a set of data samples (vectors) approximately drawn from a union of multiple subspaces, our goal is to cluster the samples into their respective subspaces and remove possible outliers as well. To this end, we propose a novel objective function named Low-Rank Representation (LRR), which seeks the lowest-rank representation among all the candidates that can represent the data samples as linear combinations of the bases in a given dictionary. It is shown that the convex program associated with LRR solves the subspace clustering problem in the following sense: When the data is clean, we prove that LRR exactly recovers the true subspace structures; when the data are contaminated by outliers, we prove that under certain conditions LRR can exactly recover the row space of the original data and detect the outlier as well; for data corrupted by arbitrary sparse errors, LRR can also approximately recover the row space with theoretical guarantees. Since the subspace membership is provably determined by the row space, these further imply that LRR can perform robust subspace clustering and error correction, in an efficient and effective way.
Article
This paper proposes an innovative algorithm named 2D-LDA, which directly extracts the proper features from image matrices based on Fisher’s Linear Discriminant Analysis. We experimentally compare 2D-LDA to other feature extraction methods, such as 2D-PCA, Eigenfaces and Fisherfaces. And 2D-LDA achieves the best performance.
Article
Radiation-induced normal-tissue toxicities are common, complex, and distressing side effects that affect 90% of patients receiving breast-cancer radiotherapy and 40% of patients post radiotherapy. In this study, the authors investigated the use of spectrophotometry and ultrasound to quantitatively measure radiation-induced skin discoloration and subcutaneous-tissue fibrosis. The study's purpose is to determine whether skin discoloration correlates with the development of fibrosis in breast-cancer radiotherapy. METHODS : Eighteen breast-cancer patients were enrolled in our initial study. All patients were previously treated with a standard course of radiation, and the median follow-up time was 22 months. The treated and untreated breasts were scanned with a spectrophotometer and an ultrasound. Two spectrophotometer parameters-melanin and erythema indices-were used to quantitatively assess skin discoloration. Two ultrasound parameters-skin thickness and Pearson coefficient of the hypodermis-were used to quantitatively assess severity of fibrosis. These measurements were correlated with clinical assessments (RTOG late morbidity scores). Significant measurement differences between the treated and contralateral breasts were observed among all patients: 27.3% mean increase in skin thickness (p < 0.001), 34.1% mean decrease in Pearson coefficient (p < 0.001), 27.3% mean increase in melanin (p < 0.001), and 22.6% mean increase in erythema (p < 0.001). All parameters except skin thickness correlated with RTOG scores. A moderate correlation exists between melanin and erythema; however, spectrophotometer parameters do not correlate with ultrasound parameters. Spectrophotometry and quantitative ultrasound are objective tools that assess radiation-induced tissue injury. Spectrophotometer parameters did not correlate with those of quantitative ultrasound suggesting that skin discoloration cannot be used as a marker for subcutaneous fibrosis. These tools may prove useful for the reduction of radiation morbidities and improvement of patient quality of life.
Article
The development of acute radiation erythema is a common phenomenon among patients under-going radiotherapy treatment. Because of the absence of reliable objective classification methods, the degree of skin reaction can at present mainly be judged subjectively in the clinic. This has motivated the present preliminary study,concerning the first steps in the development of an objective method for skin reaction classification. Three non-invasive techniques were used:near-infrared (NIR) spectroscopy, laser Doppler perfusion imaging and digital photography. The NIR spectra were analysed with principal component analysis (PCA), and the results from the other two with traditional univariate methods. Measurements were made on breast cancer patients who had been exposed to different irradiation doses. A total of 28 breast cancer patients participated one to three times each; 12 were treated with photons at 4 or 6MeV and 16 were treated with high-energy electrons between 10 and 20 MeV to a maximum dose of 50 Gy. PCA of NIR spectra shows that information on radiation dose lies mainly in the first principal component. It is observed that the higher the dose the higher the score value. The results from the laser Doppler measurements show that in 79% of the cases the perfusion increases significantly with radiation dose. Analysis of the digital photography shows that a proposed skin redness index(SRI), increases with a higher radiation dose. However,the increase in most cases is not significant. By combining all data, correlation to radiation doses was seen for 74% of the patients who participated more than once. All three non-invasive methods correlate with the radiation dose but to various degrees. NIR spectroscopy, laser Doppler and a combination of the three techniques are the most promising methods for characterising erythema.
Article
To evaluate nursing practice in Flanders (Belgium) regarding skin care during radiotherapy and the effect of the introduction of an evidence based protocol on daily nursing practice. Nurses working at radiotherapy departments in Flanders were invited to complete a 58-item questionnaire. The survey was undertaken in 2001 (n=67) and end of 2006 (n=89). Following the survey in 2001 an evidence based skin care protocol was made available for radiotherapy nurses and presented at their respective radiotherapy services. The questionnaire asked to what extend they advised their patients about skin care topics grouped in four sections: prevention, erythema, dry desquamation, moist desquamation. The surveys revealed large varieties in the management of skin reactions although there seems to be less variety and more consensus in the 2006 survey. Regarding preventive advice and the advice in case of erythema, dry desquamation and/or moist desquamation a major improvement was observed in the adoption of key principles such as washing and hydrating the irradiated site and the use of occlusive dressings and the omission of outdated techniques such as talcum powder, Eosin 2% and Gentian violet. The management of skin reactions does not always correspond with current scientific knowledge. However, the results of this study show that the dissemination and implementation of a skin care protocol enhanced standardization in Flanders, improved adheration to evidence based guidelines and lead to the disappearance of outdated ritualistic practices.
Article
The Wiener filter can be used in place of the matched filter in correlation based pattern recognition. It has been shown to be capable of detecting a target in severe clutter backgrounds provided the clutter power spectrum is included in the filter transfer function. It is shown here that the performance degrades very markedly if a different background from that used to create the filter is present at the input. However, multiple input scene power spectrum averaging is shown to considerably improve the performance, even when....
Article
The response of the skin to ionizing radiation has important implications both for the treatment of malignant disease by radiation and for radiological protection. The structural organization of human skin is described and compared with that of the pig, with which it shows many similarities, in order that the response of the skin to ionizing radiation may be more fully understood. Acute radiation damage to the skin is primarily a consequence of changes in the epidermis; the timing of the peak of the reaction is related to the kinetic organization of this layer. The rate of development of damage is independent of the radiation dose, since this is related to the natural rate of loss of cells from the basal layer of the epidermis. Recovery of the epidermis occurs as a result of the proliferation of surviving clonogenic basal cells from within the irradiated area. The presence of clonogenic cells in the canal of the hair follicle is important, particularly after non-uniform irradiation from intermediate energy beta-emitters. The migration of viable cells from the edges of the irradiated site is also significant when small areas of skin are irradiated. Late damage to the skin is primarily a function of radiation effects on the vasculature; this produces a wave of dermal atrophy after 16-26 weeks. Dermal necrosis develops at this time after high doses. A second phase of dermal thinning is seen to develop after greater than 52 weeks, and this later phase of damage is associated with the appearance of telangiectasia. Highly localized irradiation of the skin, either to a specific layer (as may result from exposure to very low energy beta-emitters) or after exposure to small highly radioactive particles, 'hot particles', produces gross effects that become visibly manifest within 2 weeks of exposure. These changes result from the direct killing of the cells of the skin in interphase after doses greater than 100 Gy. Dose-effect curves have been established for the majority of these deterministic endpoints in the skin from the results of both experimental and clinical studies. These are of value in the establishment of safe radiation dose limits for the skin.
Article
The design and performance of an instrument for quantifying ultraviolet-induced cutaneous erythema are discussed. If the instrument is used to record an 'erythema index' at a site on the skin before and after irradiation, the difference between those two readings is essentially related to an increase in vasodilation and is largely independent of the melanin content of the epidermis.
Article
A theoretical treatment has been developed for the optical properties of a layered structure which absorbs and scatters light. This theory predicts that the logarithm of the inverse of reflectance (LIR) of the surface should be a useful parameter for the examination of that structure. This approach has been applied to a study of skin in vivo. An instrument was constructed for use in clinical situations to measure the LIR spectrum of skin over the visible region of the spectrum (450-760 nm). The contributions to the observed spectra made by pigments and the skin structure were deduced by reference to the theoretical model. Numerical indices were used to quantify the changes in skin haemoglobin content following the application of vasoconstricting preparations. The indices also provided a means of measuring erythema and melanin pigmentation induced in the skin by exposure to ultraviolet radiation. The assessments made using this instrument were more reproducible and sensitive than judgments made by eye.
Article
Dose-response relationships have been studied using an ordinal visual scale and reflectance spectrophotometry data from 123 treatment sites on 110 patients treated with 10 dose fractions over 12-14 days. Dose rates varied between 3 and 240 Gy/h and total doses of between 25 and 41 Gy were given using teletherapy apparatus. We found qualitative scoring of erythematous skin reactions to be subject to considerable inter- and intra-observer variation. Reflectance spectrophotometry provided more reproducible information, some of which was undetectable by naked eye. Baseline erythema readings were significantly higher in male patients and at anatomical sites of previous heavy UV exposure. In addition, a pronounced decline in erythema readings during the second week of therapy and 'reciprocal vicinity' (abscopal) effects adjacent to the field, undetected by the eye, were observed in a subset of patients. Meaningful dose-response relationships could be derived only from reflectance data with peak change from the pretreatment baseline measure providing the best discrimination. Peak erythema measures following treatment were found to depend on the age and gender of the patient as well as the treatment site and its baseline erythema measurement. This was independent of the total dose administered or the instantaneous dose rate at which it was delivered. The rate of erythema development was also dose rate dependent but only weakly dependent on the biological dose intensity (Gy equiv./day) of the treatment course. The data raise the question of whether irradiation-induced erythema is exclusively a secondary phenomenon occurring as a result of basal cell killing. The short repair half time value of 0.06 h obtained by direct analysis is perplexing and may reflect a dose rate-dependent physiological vasodilatory response to irradiation and/or a multi-component cellular repair process.
Article
To evaluate the long term clinical significance of tumor oxygenation in a population of head and neck cancer patients receiving radiotherapy and to assess changes in tumor oxygenation during the course of treatment. Patients with head and neck cancer receiving primary RT underwent pretreatment polarographic tumor oxygen measurement of the primary site or a metastatic neck lymph node. Treatment consisted of once daily (2 Gy/fraction to a total dose of 66-70 Gy) or twice daily irradiation (1.25 Gy/fraction to 70-75 Gy) to the primary site. Twenty-seven patients underwent a second series of measurements early in the course of irradiation. Sixty-three patients underwent pretreatment tumor oxygen assessment (primary site, n = 24; nodes, n = 39). The median pO2 for primary lesions was 4.8 mmHg, and it was 4.3 mmHg for cervical nodes. There was a weak association between anemia and more poorly oxygened tumors, but many non-anemic patients still had poorly oxygenated tumors. Repeat assessments of tumor oxygenation after 10-15 Gy were unchanged compared to pretreatment baselines. Poorly oxygenated nodes pretreatment were more likely to contain viable residual disease at post-radiation neck dissection. Median follow-up time for surviving patients was 20 months (range 3-50 months). Hypoxia (tumor median pO2 <10 mmHg) adversely affected 2 year local-regional control (30 vs. 73%, P = 0.01), disease-free survival (26 vs. 73%, P = 0.005), and survival (35 vs. 83%, P = 0.02). Tumor oxygenation affects the prognosis of head and neck cancer independently of other known prognostic variables. This parameter may be a useful tool for the selection of patients for investigational treatment strategies.
Article
Radiation skin reactions occur in the majority of cases of patients undergoing radiotherapy for breast cancer with varying degrees of severity. Guidelines for skin care and for the use of topical agents and dressings have developed over the years of practice but there is little empirical evidence on which to base a decision for best practice. This paper describes the incidence of radiation skin reactions in a sample of 126 women treated for breast cancer post-lumpectomy. The results show that by the end of whole breast irradiation between 4-8% of patients will have no reaction and less than 10% will have moist desquamation as measured by the RTOG acute scoring system. The majority of patients did not require application of a topical agent during the treatment period. Statistical analysis of relationships between the severity of radiation skin reaction and the use of topical agents found no support for additional healing or preventative benefit. However, these topical agents were found to promote comfort. The use of Fixomull as a protector and potential preventive measure for moist desquamation is described.
Article
Clinical evaluation of acne is usually based on direct visual assessment and ordinary flash photography, both of which are compromised by viewer subjectivity. It is difficult to accurately assess individual acne lesions and to observe early response to therapy. Standard flash photography has inherent limitations owing to the physics of light; it does not permit consistent visualization of subtle cutaneous characteristics like erythema or microcomedones, and it tends to blur distinctions between active inflammatory lesions and older hyperpigmented macules. Over the last decade there has been increasing interest in newer techniques aimed at increasing the accuracy and objectivity of acne evaluation. These include parallel-polarized light photography, cross (or perpendicular)-polarized light photography, videomicroscopy, and fluorescence photography. This article will review the advances of the past decade and summarize new techniques to evaluate acne lesions. Moreover, findings of a study that evaluated the course of individual acne lesions and the effects of adapalene gel 0.1% on inflammatory and non-inflammatory acne lesions will be viewed. In this study, the use of parallel-polarized and cross-polarized photography, in combination with videomicroscopy and sebum production measurement, provided objective, detailed information on the evolution of different variable acne lesions and their response to adapalene gel 0.1%. Adapalene treatment produced rapid resolution of inflammatory and non-inflammatory lesions, and inhibited formation of new lesions. Sebum secretion rates also declined during treatment. Use of the new assessment techniques proved to be a valuable, non-invasive and reliable method of assessing acne vulgaris and its response to treatment.
Article
Background/purpose: Colour measurements obtained from digitized images have been proposed as a simple and cost-effective way to evaluate skin colour and the activity of treatments. The main disadvantage of the method is the fact that it is highly dependent on ambient light: even if an accurate control of subjects' illumination is provided, readings remain not comparable among different laboratories. The purpose of this study was to develop a highly reproducible system for computerized colour image analysis of skin erythema, making it possible to compare readings from different environmental light conditions. Patients and methods: Three hundred and forty-eight Caucasian adult healthy subjects (age range: 18-60 years) of both sexes (14% males, 86% females), were enrolled in the study by 49 dermatologists distributed all over Italy. They were recruited among patients who required aesthetic treatments involving skin erythema, like chemical peeling and laser epilation. Once the treatment was administered, clinical evaluations and pictures were taken at the level of treated areas. Visual assessment of erythema was done on the basis of conventional clinical grades (0 = absent; 1 = slight; 2 = moderate; 3 = intense). The clinicians participating in the study were asked to put a standard colour marker (red, green and blue coloured self-adhesive ring) in the photographed skin area. The difference between r, g, b values of photographed colour markers on the skin of single patients participating in the study and the r, g, b values obtained photographing the colour marker in fixed illumination conditions was used to adjust skin colour measurements. Then erythema index (E.I) on digitized images was calculated subtracting red value to green one by averaging procedure of different pixels. Results: Erythema index. average value among the groups divided according to the conventional clinical score increased progressively from score 0-2, while it decreased from score 2 to score 3. The differences in E.I. mean values among the score groups (0 vs. 1, 1 vs. 2, 2 vs. 3) were statistically significant (P < 0.05). Conclusion: We developed a method for the measurement of skin erythema using digital camera, normalized r, g, b colour co-ordinate system and computerized calculation of E.I. Clinical usefulness of our method for absent, slight and moderate erythema, was demonstrated. For intense erythema lesions we did not find a correspondence between clinical and computerized evaluation, probably due to other factors involved in skin inflammation (e.g. oedema).
Article
To investigate the cause of acute skin toxicity observed in the treatment of head-and-neck cancer with extended-field intensity-modulated radiotherapy (EF-IMRT). EF-IMRT was used to treat head-and-neck cancer, with the gross target volume receiving 70 Gy and the clinical target volume 60 Gy. A thermoplastic mask covering the head, neck, and shoulder was used for immobilization. Dosimetric studies were conducted to investigate the possible causes of the skin reactions, such as the bolus effect of the mask, the use of multiple tangential beams with IMRT plans, and the way in which the physicians contoured the lymph nodes. The dose-volume histograms of conventional opposed-lateral fields were compared with that of the multiple tangential EF-IMRT fields. IMRT plans with neck nodes contoured up to and including the skin surface were compared with plans that contoured the neck nodes 5 mm away from the skin surface. In addition, IMRT plans defining the skin as a sensitive structure were compared with plans that did not define the skin as a sensitive structure. All plans were created using an anthropomorphic Rando phantom, and the skin doses were measured with and without the mask. In each measurement, 6 thermoluminescent dosimeters (TLDs) were placed at the lateral and medial surfaces of the neck. For all four plans, the measured skin doses with the mask were consistently higher than those without the mask. The average dose increase was about 18% owing to the bolus effect of the mask. Multiple tangential fields used in IMRT plans contributed to an increase in skin dose by about 19% and 27%, with and without the mask, respectively. If the skin of the neck was contoured as a sensitive structure for dose optimization, the volume of skin that received >45 Gy was further reduced by about 20%. Five patients immobilized with head and shoulder masks were treated with EF-IMRT plans with the neck nodes carefully delineated away from the skin surface. The neck skin was identified as a sensitive structure for dose optimization. Grade 1 toxicity was observed in 3 patients, Grade 2 in 1 patient, and Grade 3 in 1 patient toward the end of treatment. Multiple factors contributed to the observed acute skin reaction for head-and-neck cancer patients treated with EF-IMRT. By taking into consideration the skin as a sensitive structure during inverse planning, it was possible to reduce the skin dose to a tolerable level without compromising tumor target coverage.
Article
Radiotherapy is an important modality in the treatment of non-melanoma skin cancers. While the majority of patients will be adequately treated without the need for radiotherapy, there are factors that may favour a recommendation for radiotherapy. The established roles of modern radiotherapy include the definitive, adjuvant and palliative settings. It is important that clinicians treating skin cancers have an understanding and awareness of these roles. The aim of this article is to present an overview of radiotherapy in the current Australian setting.
Article
The possibility of treating skin carcinomas of the pinna with radiotherapy is somewhat under discussion and scarcely known. Therefore the aim of the study was to evaluate the effectiveness and safety of dermatologic radiotherapy in a series of patients affected by basal or squamous cell carcinoma of the pinna. A retrospective study was performed on 108 patients affected by 115 carcinomas of the pinna (99 basal cell carcinomas, 16 squamous cell carcinomas) without involvement of the external auditory canal. Radiotherapy was performed with kilovoltage techniques (55-120 kV) and the total doses administered ranged from 45 to 70 Gy (105 Gy in one case only), with different fractionations. The mean follow-up was 28.80 months. Complete remission was obtained in 111 lesions (96.52%) and partial remission in one (0.87%), as evaluated 1 month after the end of radiotherapy. No response was observed in two lesions (1.74%). The response was not evaluable in one lesion (0.87%). During follow up a relapse was observed in 12 lesions (all basal cell carcinomas): nine central and three marginal to the irradiation field. The 5-year cure-rate from the end of radiotherapy was 78%. The cosmetic results were evaluated as good or acceptable in 88.28% of lesions. No complications nor sequelae to the treatment were observed. The results obtained confirm the possibility of treating epithelial skin neoplasms of the pinna with dermatologic radiotherapy, which can afford high-remission percentages without damaging cartilaginous tissue.
Article
Background: The use of an adequate initial dose of ultraviolet A (UVA) radiation for photochemotherapy is important to prevent burns secondary to overdosage, meanwhile avoiding a reduced clinical improvement and long-term risks secondary to underdosage. The ideal initial dose of UVA can be achieved based on the phototype and the minimal phototoxic dose (MPD). The objective measurement of constitutive skin color (colorimetry) is another method commonly used to quantify the erythematous skin reaction to ultraviolet radiation exposure. The aim of this study was to determine variations in MPD and constitutional skin color (coordinate L(*)) within different phototypes in order to establish the best initial dose of UVA radiation for photochemotherapy patients. Methods: Thirty-six patients with dermatological conditions and 13 healthy volunteers were divided into five groups according to phototype. Constitutional skin color of the infra-axillary area was assessed by colorimetry. The infra-axillary area was subsequently divided into twelve 1.5 cm(2) regions to determine the MPD; readings were performed 72 h after oral administration of 8-methoxypsoralen (MOP) followed by exposure of the demarcated regions to increasing doses of UVA. Results: The majority of the participants were women (73.5%) and their mean age was 38.8 years. The MPD ranged from 4 to 12 J/cm(2) in phototypes II and III; from 10 to 18 J/cm(2) in type IV; from 12 to 24 J/cm(2) in type V and from 18 to 32 J/cm(2) in type VI. The analysis of colorimetric values (L(*) coordinate) and MPD values allowed the definition of three distinctive groups of individuals composed by phototypes II and III (group 1), types IV and V (group 2), and phototype VI (group 3). Conclusions: MPD and L(*) coordinate showed variation within the same phototype and superposition between adjacent phototypes. The values of the L(*) coordinate and the MPD lead to the definition of three distinct sensitivity groups: phototypes II and III, IV and V and type VI. Also, the MPD values bear a strong correlation to coordinate L(*) values. Mean MPD values described for each of the three major sensitivity groups were higher than the values commonly used in clinical settings for the different phototypes. Therefore, phototype alone is not a good parameter to define the initial UVA dose. MPD and colorimetry could be used in pre-treatment evaluation of patients who are to be submitted to photochemotherapy, in a non-invasive and more accurate way when compared with the classical phenotype clinical criteria.
Article
Photography has been used in human skin research for some time. With the advent of digital photography in recent years, its use has increased. However, the focus has now turned from documentation to actual analysis and quantification of skin color changes. The advantages of digital photography outweigh any shortcomings as long as consistent, standardized procedures are followed and quality control is implemented. We present a simple procedure to standardize images and discuss a computer-assisted digital image evaluation (CADIE) technique to quantify skin color changes following UV exposure. The CADIE approach is illustrated with examples from two different studies on UV responses in human skin. Using the Commission Internationale de l'Eclairage L*a*b* color coordinate system in combination with a personal computer and image-editing software, we analyzed digital images obtained in these two studies. We demonstrate the feasibility of using digital photography for objective evaluation of UV erythema in different racial/ethnic groups and for measuring pigmentation changes caused by repeated exposures over a period of several weeks. Our results indicate how objective assessment using CADIE can be an adjunct to visual and optical observation in clinical and scientific evaluations.
Article
Visual assessment remains one of the "gold standard" methods of assessing skin color and a number of tools are currently available to reduce the interobserver variability. Ultraviolet light examination remains a mainstay of the assessment of pigmentary disorders, while polarized light photography is useful for the appraisal of dermal changes, in particular those related to vascularity. With the introduction of modern instruments, reflectance spectroscopy using tristimulus colorimeters or narrowband spectrophotometers provides a convenient, objective, and reproducible methodology for the evaluation of pigmentation and skin color. In vivo confocal scanning laser microscopy is a powerful technique for the examination of pigmented lesions, which shows promise in the detection and diagnosis of early melanoma. Dermoscopy is also useful for the differential diagnosis of benign melanocytic lesions and melanoma, and its use has been shown to significantly improve diagnostic accuracy.
Article
Evoked potentials (EPs) typically contain components that last up to several seconds. In order to save time and study adaptation effects, stimuli are often presented at high stimulation rates. Unfortunately, such protocols often suffer from a response overlap problem. Techniques based on Continuous Loop Averaging Deconvolution (CLAD) have been developed to formulate circular convolution to restore the source EP. These techniques, however, are sensitive to the additive noise and do not perform well when stimulus sequences with poor noise attenuation properties are chosen. This study offers a solution to this problem by applying Wiener theory to obtain an optimal filter that adapts the ratio of noise-to-signal by estimating the power spectra of both noise and signal using non-parametric or parametric methods. Experiments are conducted on simulation data and Auditory Evoked potentials (AEPs) acquired from human subjects to demonstrate the validity of the proposed theory. The results show that the Wiener deconvolution method improves the quality of the responses acquired with sequences with poor noise attenuation in the presence of high noise levels compared to the straight CLAD method. The results are comparable to responses obtained by conventional and Maximum Length Sequence (MLS) methods.
Article
To review published studies evaluating interventions for the prevention and management of radiation skin reactions/dermatitis. Research studies, review articles, and clinical practice guidelines. There is insufficient evidence in the literature to recommend specific topical or oral agents in the prevention or management of skin reactions. Recent limited evidence suggests that the use of calendula cream may reduce the incidence of grade 2 and 3 reactions in women with breast cancer. Additionally, early studies evaluating the use of barrier films or creams may improve moist desquamation. Oncology nurses need to increase their awareness of the evidence or lack of evidence when recommending interventions to their patients. Further research is required to evaluate interventions in the prevention and management of radiation dermatitis.