Synchronized in vivo measurements of skin hydration and trans-epidermal water loss. Exploring their mutual influences.

OBJECTIVE: To explore the relationship between skin surface hydration and Trans-Epidermal Water Loss (TEWL) when simultaneously measured. METHODS: Six circular skin areas of the forearms (3 per forearm, 3 cm in diameter) of 12 Caucasian women were used as models. 4 prototypes of formulae of different compositions containing glycerol at different concentrations 7%, 10% and 40% were used as models of hydrating products. One formula (glycerol-free) was used as control vehicle. Standardized applications of formulae (2 mg/cm2 ) were performed on 5 skin sites chosen at random, the other being left as bare/control. A recently marketed instrumental device that records the skin surface hydration and TEWL on a small skin area in a simultaneous manner was used. Measurements were carried out at T0 (pre-application), at 1 h (T1) and 5 h (T5) post applications on two close sites within the 6 defined areas of both forearms. RESULTS: The new instrumental device allowed to clearly differentiate the 5 formulae (i.e. 7% vs. 10%) with regard the dose effect brought by glycerol (7%, 10%, 40%) and to record their lingering effects at T1 and T5. Both parameters were found significantly and negatively correlated, i.e. the higher the skin hydration, the lower the TEWL. The 40% concentration of glycerol, that leads to the highest skin hydration, brings a drop in the TEWL by about a two-fold factor. Skin hydration of bare skin and control/vehicle sites showed minor and non-significant changes along 5 h. Instead, the control/ vehicle slowed down the TEWL to a slight extent. CONCLUSION: The use of this new instrumental device shed a new light on the mutual and inverse relationships between skin hydration and TEWL. Results suggest that, at high concentration, glycerol leads to largely increase the water content of both epidermal and dermal compartments, possibly leading to structural changes in the skin relief.

OBJECTIF: D'explorer les relations mutuelles entre l'hydratation cutanée et la perte insensible en eau (PIE) quand elles sont mesurées simultanément. MÉTHODES: 6 zones circulaires des avant-bras (3 par zone, diamètre 3 cm) de 12 femmes Caucasiennes ont été utilisées comme modèles. 4 prototypes de formules, de compositions différentes contenant du glycérol à différentes concentrations (7%, 10%, 40%) furent réalisés et utilisés comme modèles de produits hydratants. Une formule sans glycérol fut utilisée en tant que contrôle. Des applications standardisées (2 mg/cm2 ) ont été effectuées sur 5 zones de façon aléatoire, la sixième restant nue en tant que contrôle. Un appareil nomade récemment disponible sur le marché qui enregistre l'hydratation et la PIE simultanément sur une petite surface cutanée a été utilisé. Deux mesures à deux endroits voisins de chaque zone ont été conduites à T0 (avant applications), 1 heure (T1) et 5 heures (T5) après. RÉSULTATS: Ce nouvel instrument permet de clairement différencier les 5 formules dans l'effet dose apporté par le glycérol (0, 7%, 10%, 40%) et de suivre leur rémanence dans le temps (T5 vs. T1). Les deux paramètres ont été trouvés négativement corrélés de manière significative, c'est-à-dire qu'une plus forte hydratation correspondant à une plus faible PIE. La formule à 40% de glycérol, qui a conduit à la plus forte hydratation, a ainsi entrainé une chute de la PIE d'environ 50%. La peau nue comme celle de la formule contrôle n'ont pas conduit à de modifications notables et significatives de l'hydratation. La formule contrôle a conduit à une légère chute de la PIE. CONCLUSION: L'utilisation de ce nouvel instrument semble apporter un éclairage nouveau sur les relations mutuelles (et inverses) entre l'hydratation cutanée et la PIE. Les résultats suggèrent qu'à forte concentration, le glycérol conduit à un fort accroissement de la teneur en eau de l'épiderme et du derme, avec de possibles conséquences structurelles du relief cutané.

Morphological criteria of feminine upper eyelashes, quantified by a new semi-automatized image analysis: Application to the objective assessment of mascaras.

BACKGROUND: The wide diversity of feminine eyelashes in shape, length, and curvature makes it a complex domain that remains to be quantified in vivo, together with their changes brought by application of mascaras that are visually assessed by women themselves or make-up experts. METHODS: A dedicated software was developed to semi-automatically extract and quantify, from digital images (frontal and lateral pictures), the major parameters of feminine eyelashes of Mexican and Caucasian women and to record the changes brought by the applications of various mascaras and their brushes, being self or professionally applied. RESULTS: The diversity of feminine eyelashes appears as a major influencing factor in the application of mascaras and their related results. Eight marketed mascaras and their respective brushes were tested and their quantitative profiles, in terms of coverage, morphology, or curvature were assessed. Standard applications by trained aestheticians led to higher and more homogeneous deposits of mascara, as compared to those resulting from self-applications. CONCLUSION: The developed software appears a precious tool for both quantifying the major characteristics of eyelashes and assessing the making-up results brought by mascaras and their associated brushes.

A new tool to quantify the geometrical characteristics of facial skin pores. Changes with age and a making-up procedure in Caucasian women.

BACKGROUND: Facial skin pores (FSP) are common and benign signs that generate frequent esthetic concerns or complaints. Despite their worldwide prevalence, related literature remains scarce. Hence, a new device has been developed and applied to validating studies, aiming at best describing FSP as they are self-perceived, i.e. their anatomic features, their possible alterations with age and their appearance after application of a make-up product. METHODS: Dermascore+® is an imaging device dedicated to a direct observation and acquisition of various characteristics of the skin surface. Images are captured under a high magnification and under different lighting configurations, to highlight the skin relief, based upon parallel polarized images. Dedicated software allows FSP to being detected and their morphological parameters to being extracted and computed. By measuring each detected FSP in a given region of interest, a statistically significant impact of both age and an applied cosmetic product upon their morphological features can be observed and quantified. RESULTS: Although the size and density of FSP are not affected by aging, their shape becomes elongated. A few tested make up products show variable effects that closely correlate with visual assessments made by trained estheticians. CONCLUSION: The shape of FSP present on cheeks shows age-related changes, toward a more elongated aspect, likely linked to a progressively altered (more isotropic) skin surface micro-relief. The new tool Dermascore+® allows foundations to being rapidly differentiated and screened according to their variable effects upon the visual appearance through instrumental, objective depiction of FSP.

MicroRT-small animal conformal irradiator.

A novel small animal conformal radiation therapy system has been designed and prototyped: MicroRT. The microRT system integrates multimodality imaging, radiation treatment planning, and conformal radiation therapy that utilizes a clinical 192Ir isotope high dose rate source as the radiation source (teletherapy). A multiparameter dose calculation algorithm based on Monte Carlo dose distribution simulations is used to efficiently and accurately calculate doses for treatment planning purposes. A series of precisely machined tungsten collimators mounted onto a cylindrical collimator assembly is used to provide the radiation beam portals. The current design allows a source-to-target distance range of 1-8 cm at four beam angles: 0 degrees (beam oriented down), 90 degrees, 180 degrees, and 270 degrees. The animal is anesthetized and placed in an immobilization device with built-in fiducial markers and scanned using a computed tomography, magnetic resonance, or positron emission tomography scanner prior to irradiation. Treatment plans using up to four beam orientations are created utilizing a custom treatment planning system-microRTP. A three-axis computer-controlled stage that supports and accurately positions the animals is programmed to place the animal relative to the radiation beams according to the microRTP plan. The microRT system positioning accuracy was found to be submillimeter. The radiation source is guided through one of four catheter channels and placed in line with the tungsten collimators to deliver the conformal radiation treatment. The microRT hardware specifications, the accuracy of the treatment planning and positioning systems, and some typical procedures for radiobiological experiments that can be performed with the microRT device are presented.

Dose response explorer: an integrated open-source tool for exploring and modelling radiotherapy dose-volume outcome relationships.

Radiotherapy treatment outcome models are a complicated function of treatment, clinical and biological factors. Our objective is to provide clinicians and scientists with an accurate, flexible and user-friendly software tool to explore radiotherapy outcomes data and build statistical tumour control or normal tissue complications models. The software tool, called the dose response explorer system (DREES), is based on Matlab, and uses a named-field structure array data type. DREES/Matlab in combination with another open-source tool (CERR) provides an environment for analysing treatment outcomes. DREES provides many radiotherapy outcome modelling features, including (1) fitting of analytical normal tissue complication probability (NTCP) and tumour control probability (TCP) models, (2) combined modelling of multiple dose-volume variables (e.g., mean dose, max dose, etc) and clinical factors (age, gender, stage, etc) using multi-term regression modelling, (3) manual or automated selection of logistic or actuarial model variables using bootstrap statistical resampling, (4) estimation of uncertainty in model parameters, (5) performance assessment of univariate and multivariate analyses using Spearman's rank correlation and chi-square statistics, boxplots, nomograms, Kaplan-Meier survival plots, and receiver operating characteristics curves, and (6) graphical capabilities to visualize NTCP or TCP prediction versus selected variable models using various plots. DREES provides clinical researchers with a tool customized for radiotherapy outcome modelling. DREES is freely distributed. We expect to continue developing DREES based on user feedback.

A comparison of Monte Carlo dose calculation denoising techniques.

Recent studies have demonstrated that Monte Carlo (MC) denoising techniques can reduce MC radiotherapy dose computation time significantly by preferentially eliminating statistical fluctuations ('noise') through smoothing. In this study, we compare new and previously published approaches to MC denoising, including 3D wavelet threshold denoising with sub-band adaptive thresholding, content adaptive mean-median-hybrid (CAMH) filtering, locally adaptive Savitzky-Golay curve-fitting (LASG), anisotropic diffusion (AD) and an iterative reduction of noise (IRON) method formulated as an optimization problem. Several challenging phantom and computed-tomography-based MC dose distributions with varying levels of noise formed the test set. Denoising effectiveness was measured in three ways: by improvements in the mean-square-error (MSE) with respect to a reference (low noise) dose distribution; by the maximum difference from the reference distribution and by the 'Van Dyk' pass/fail criteria of either adequate agreement with the reference image in low-gradient regions (within 2% in our case) or, in high-gradient regions, a distance-to-agreement-within-2% of less than 2 mm. Results varied significantly based on the dose test case: greater reductions in MSE were observed for the relatively smoother phantom-based dose distribution (up to a factor of 16 for the LASG algorithm); smaller reductions were seen for an intensity modulated radiation therapy (IMRT) head and neck case (typically, factors of 2-4). Although several algorithms reduced statistical noise for all test geometries, the LASG method had the best MSE reduction for three of the four test geometries, and performed the best for the Van Dyk criteria. However, the wavelet thresholding method performed better for the head and neck IMRT geometry and also decreased the maximum error more effectively than LASG. In almost all cases, the evaluated methods provided acceleration of MC results towards statistically more accurate results.

Dependence of radiochromic film optical density post-exposure kinetics on dose and dose fractionation.

Radiochromic film (RCF) has been shown to be a precise and accurate secondary planar dosimeter for acute exposure radiation fields. However, its application to low dose-rate brachytherapy has been questioned because of possible dose-rate effects. To address this concern, we have measured the optical density (OD) of Model 55-2 RCF as a function of time (interval between the completion of irradiation and densitometry using a 633 nm laser scanner) following exposure (from less than 1 hour to 90 days) for single and split doses from 1 Gy to 100 Gy. Our work demonstrates that film darkening as a function of post-irradiation time depends significantly on total dose, with films exposed to lower doses developing faster than films given higher doses. At 1 Gy, the OD 90 days after exposure is 200% larger than that measured 1 h after exposure compared to a 20% increase over 90 days for doses larger than 20 Gy. An empirical model with time-independent, fast and slow growth terms was used to fit single exposure data. The dependence of the resulting best-fit parameters on dose was investigated. Splitting the dose into two fractions (20 Gy followed by doses of 1-80 Gy 24 h later) results in modest post-irradiation time-dependent changes in the total optical density (at most 15% at small doses), which dissipates within 20 hours following the second exposure. This experimental finding is consistent with the predictions of a simple cumulative dose superposition model. Overall, both experimental and empirical modeling suggest that dose-rate effects may be relatively small despite the strong dependence of film darkening kinetics on total dose. However, more experimental evaluation of radiochromic film response dependence on dose rate and dose-time-fractionation patterns is needed.