Search results for "Skin surface"
showing 8 items of 18 documents
SU-E-T-516: Limitations and Clinical Implications of the TG-43 Formalism for High-Dose-Rate Skin Brachytherapy
2013
Purpose: In high‐dose‐rate (HDR) skin brachytherapy, sources are located outside, in contact with, or implanted at some depth below the skin surface. Nowadays, most TPS use the TG‐43 formalism that is based on sources within an infinite water medium, without accounting for the scatter defect due to surrounding air. The purpose of the present study is to evaluate the limitations of the TG‐43 formalism in HDR skin brachytherapy. Methods: This study examined two HDR sources (Ir‐192 and Co‐60) together with a hypothetical Yb‐169 source. Dose distributions were obtained using Monte Carlo methods (i.e., GEANT4). The following configurations were investigated: 1)A typical clinical case consisting …
Subcutaneous Veins Depth Estimation Method Using Monte Carlo Simulations
2015
International audience; Subcutaneous veins localization is basic and important step for any intravenous medication administration. Due to different physiological characteristics, mainly darker skin tone, scars or dehydrated condition of patients, medical staff face difficulty in veins localization. Through near infrared imaging technology the veins can be visualized due to high contrast between veins and skin tissue in this modality. Information on the depth of veins is equally important for proper catheterization or venipuncture procedures. Patients have different veins depth due to the different amount of fat present in the subcutaneous layer. The depth of veins from the skin surface cann…
Dosimetry comparison between TG-43 and Monte Carlo calculations using the Freiburg flap for skin high-dose-rate brachytherapy
2012
Abstract Purpose The purpose of this work was to evaluate whether the delivered dose to the skin surface and at the prescription depth when using a Freiburg flap applicator is in agreement with the one predicted by the treatment planning system (TPS) using the TG-43 dose-calculation formalism. Methods and Materials Monte Carlo (MC) simulations and radiochromic film measurements have been performed to obtain dose distributions with the source located at the center of one of the spheres and between two spheres. Primary and scatter dose contributions were evaluated to understand the role played by the scatter component. A standard treatment plan was generated using MC- and TG-43-based TPS appl…
Remote photoplethysmography device with adaptive illumination for skin microcirculation assessment
2020
Measuring blood perfusion is important in medical care. However, currently available devices to measure blood perfusion are bulky, expensive and not easy-to-use. In this work a compact and portable low-cost prototype device for remote monitoring of palm skin microcirculation has been developed. Presented device consists of precisely controlled near-infrared illuminators (760nm peak wavelength) and video camera. The device with the custom designed software provides stable uniform illumination of curved skin surfaces, using feedback algorithm. Verification tests of this device showed improvements in the quality of skin blood perfusion maps in the case when the feedback system was used.
FPI Based Hyperspectral Imager for the Complex Surfaces : Calibration, Illumination and Applications
2022
Hyperspectral imaging (HSI) applications for biomedical imaging and dermatological applications have been recently under research interest. Medical HSI applications are non-invasive methods with high spatial and spectral resolution. HS imaging can be used to delineate malignant tumours, detect invasions, and classify lesion types. Typical challenges of these applications relate to complex skin surfaces, leaving some skin areas unreachable. In this study, we introduce a novel spectral imaging concept and conduct a clinical pre-test, the findings of which can be used to develop the concept towards a clinical application. The SICSURFIS spectral imager concept combines a piezo-actuated Fabry–Pé…
Melanin type and concentration determination using inverse model
2011
Abnormality of melanin production causes skin pigmentation disorders. Currently, assessment of treatment efficacy (under Physician's Global Assessment framework) only refers to visual conditions of skin surface and not the condition of the underlying skin layers and pigments. Albeit researches on models and simulations of light interaction with human skin have been reported, none has been specifically developed for pigmentation analysis of melanin types - eumelanin and pheomelanin. Therefore, our research objectives are to develop image analysis of skin pigmentation for classification and quantification of eumelanin and pheomelanin pigment types in human skin. In this research, the model is…
The influence of the C1-inhibitor BERINERT® and the protein-free haemodialysate ACTIHAEMYL20%® on the evolution of the depth of scald burns in a porc…
1997
Standardized deep partial-thickness burns were inflicted on domestic pigs by scalding 30 per cent of the skin surface for 25 s with 75 degrees C hot water. The animals (n = 18; weight 25-35 kg) were divided into three groups: I, control group (n = 6), Ringer's lactate only; II, haemodialysate group (n = 6), Ringer's lactate and a protein-free haemodialysate of calf-blood (ACTIHAEMYL20%; AH) and III, C1-inhibitor group (n = 6), Ringer's lactate and C1-inhibitor (C1-INH; BERINERT). Skin biopsies were taken at defined time points (4, 28, 52 and 76 h) and investigated histologically. Depth of burn was determined morphometrically after coloration with a modified MTT-staining on frozen sections o…
UV filters: From sunscreens to human body and the environment
2007
Recognition of the harmful effects of ultraviolet (UV) radiation on the skin has triggered development of organic chemicals (commonly referred as UV filters) that can absorb UV radiation and attenuate the negative effects of sunlight exposure. Depending on the properties and the intended degree of protection, a wide array of combinations is being marketed as delivering protection against most kinds of UV-induced skin damage. However, some UV filters have dermatological implications, so maximum applicable concentrations have been established. To monitor to what extent commercial products comply with the mandatory limits, several analytical methods have been used for their determination in co…