showing 33 related works from this author
Multispectral and autofluorescence RGB imaging for skin cancer diagnostics
2019
This paper presents the results of statistical clinical data, combining two diagnostic methods. A combination of two skin imaging methods – diffuse reflectance and autofluorescence – has been applied for skin cancer diagnostics. Autofluorescence (AF) and multispectral diffuse reflectance images were acquired by custom made prototype with 405 nm, 526 nm, 663 nm and 964 nm LEDs and RGB CMOS camera. Parameter p’ was calculated from diffuse reflectance images under green, red and infrared illumination, AF intensity (I’) was calculated from AF images exited at 405nm wavelength. Obtained results show that criterion p` > 1 gives possibility to discriminate melanomas and different kind of keratosis…
Melanoma-nevus differentiation by multispectral imaging
2011
A clinical trial on multi-spectral imaging of malignant and non-malignant skin pathologies comprising 22 melanomas and 59 pigmented nevi was performed in Latvian Oncology Center. Analysis of data obtained in the spectral range 450–950 nm using multispectral camera have led to a novel image processing algorithm capable to distinguish melanoma from pigmented nevi and different areas of activity of melanoma. The proposed methodology and potential clinical applications are discussed.
Evaluation of Skin Vascular Malformations’ Laser Treatment by RGB and Multi-spectral Imaging
2012
RGB imaging system for mapping and monitoring of hemoglobin changes in skin has been tested for evaluation of vascular malformations’ laser treatment. The multi-spectral imaging system was used as the reference.
Application of principal component analysis to multispectral imaging data for evaluation of pigmented skin lesions
2013
Non-invasive and fast primary diagnostics of pigmented skin lesions is required due to frequent incidence of skin cancer – melanoma. Diagnostic potential of principal component analysis (PCA) for distant skin melanoma recognition is discussed. Processing of the measured clinical multi-spectral images (31 melanomas and 94 nonmalignant pigmented lesions) in the wavelength range of 450-950 nm by means of PCA resulted in 87 % sensitivity and 78 % specificity for separation between malignant melanomas and pigmented nevi.
Multispectral autoflourescence detection of skin neoplasia using steady-state techniques
2019
In the current study were used excitation-emission matrices (EEMs) and synchronous fluorescence spectroscopy (SFS) steady-state techniques in a broad spectral regions (excitation at 220-500 nm and emission at 280-850 nm) to achieve the whole set of endogenous fluorophores, existed in normal and neoplastic cutaneous tissues. Several types of benign, dysplastic and malignant types of skin lesions were investigated ex vivo using both EEM and SFS modalities, namely the basal cell papilloma and carcinoma, pigmented nevi, dysplastic nevi, squamous cell carcinoma and malignant melanoma. Histological analysis was used as a “gold standard” for evaluation of clinical diagnosis of the lesions investig…
Image quality enhancement for skin cancer optical diagnostics
2017
The research presents image quality analysis and enhancement proposals in biophotonic area. The sources of image problems are reviewed and analyzed. The problems with most impact in biophotonic area are analyzed in terms of specific biophotonic task – skin cancer diagnostics. The results point out that main problem for skin cancer analysis is the skin illumination problems. Since it is often not possible to prevent illumination problems, the paper proposes image post processing algorithm – low frequency filtering. Practical results show diagnostic results improvement after using proposed filter. Along that, filter do not reduces diagnostic results’ quality for images without illumination de…
Towards noncontact skin melanoma selection by multispectral imaging analysis
2011
A clinical trial comprising 334 pigmented and vascular lesions has been performed in three Riga clinics by means of multispectral imaging analysis. The imaging system Nuance 2.4 (CRi) and self-developed software for mapping of the main skin chromophores were used. Spe- cific features were observed and analyzed for malignant skin melanomas: notably higher absorbance (especially as the difference of optical density relative to the healthy skin), uneven chromophore distribution over the lesion area, and the possibility to select the "melanoma areas" in the correla- tion graphs of chromophores. The obtained results indicate clinical potential of this technology for noncontact selec- tion of mel…
Rosacea assessment by erythema index and principal component analysis segmentation maps
2017
RGB images of rosacea were analyzed using segmentation maps of principal component analysis (PCA) and erythema index (EI). Areas of segmented clusters were compared to Clinician’s Erythema Assessment (CEA) values given by two dermatologists. The results show that visible blood vessels are segmented more precisely on maps of the erythema index and the third principal component (PC3). In many cases, a distribution of clusters on EI and PC3 maps are very similar. Mean values of clusters’ areas on these maps show a decrease of the area of blood vessels and erythema and an increase of lighter skin area after the therapy for the patients with diagnosis CEA = 2 on the first visit and CEA=1 on the …
<title>Amorphous chalcogenide semiconductor resists for holography and electron-beam lithography</title>
2001
The photo- and electron beam induced changes in solubility of amorphous chalcogenide semiconductor As-S-Se and As2S3 thin films have been studied. The possibilities of practical application of these materials as resists for the production of relief holograms and holographic optical elements are discussed. It is shown that the self-enhancement phenomenon of holographic recording in amorphous chalcogenide semiconductor films by light or thermal treatment can be used to increase the diffraction efficiency of the holograms.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Multi-spectral imaging analysis of pigmented and vascular skin lesions: results of a clinical trial
2011
A clinical trial comprising 266 pigmented lesions and 49 vascular lesions has been performed in three Riga clinics by means of multi-spectral imaging analysis. The imaging system Nuance 2.4 (CRI) and self-developed software for mapping of the main skin chromophores were used. The obtained results confirm clinical potential of this technology for non-contact quantitative assessment of skin pathologies.
Towards combined multispectral, FLIM and Raman imaging for skin diagnostics
2020
To explore challenges for further improvement of diagnostic performance, a project aimed at development of technology for tri-modal skin imaging by combining multispectral, fluorescence lifetime and Raman band imaging was initiated. In this study, each of the mentioned imaging modalities has been preliminary tested and updated. Four different multispectral imaging devices were tested on color standards. Picosecond laser-excited fluorescence lifetime imaging equipment was examined on ex-vivo skin samples. Finally, a new Raman spectroscopy setup with 785 nm laser was launched and tested on cell cultures and ex-vivo skin. Advantages and specific features of the tri-modal skin imaging are discu…
Noncontact monitoring of vascular lesion phototherapy efficiency by RGB multispectral imaging.
2013
A prototype low-cost RGB imaging system consisting of a commercial RGB CMOS sensor, RGB light-emitting diode ring light illuminator, and a set of polarizers was designed and tested for mapping the skin erythema index, in order to monitor skin recovery after phototherapy of vascular lesions, such as hemangiomas and telangiectasias. The contrast of erythema index (CEI) was proposed as a parameter for quantitative characterization of vascular lesions. Skin recovery was characterized as a decrease of the CEI value relative to the value before the treatment. This approach was clinically validated by examining 31 vascular lesions before and after phototherapy.
Contact and contactless diffuse reflectance spectroscopy: potential for recovery monitoring of vascular lesions after intense pulsed light treatment.
2011
Optical fiber contact probe diffuse reflectance spectroscopy and remote multispectral imaging methods in the spectral range of 400 to 1100 nm were used for skin vascular malformation assessment and recovery tracing after treatment by intense pulsed light. The results confirmed that oxy-hemoglobin relative changes and the optical density difference between lesion and healthy skin in the spectral region 500 to 600 nm may be successfully used for objective appraisal of the therapy effect. Color redness parameter a* = 2 is suggested as a diagnostic border to distinguish healthy skin and vascular lesions, and as the indicator of phototreatment efficiency. Valuable diagnostic information on large…
Analysis of skin basalioma and melanoma by multispectral imaging
2012
A clinical trial involving multi-spectral imaging of histologically confirmed 8 basaliomas and 30 melanomas was performed. Parametric maps of the melanin index, erythema index and melanoma-nevus differentiation parameter have been constructed and mutually compared. Specific features of basalioma and melanoma images were analyzed and discussed.
RGB imaging system for monitoring of skin vascular malformation's laser therapy
2012
A prototype RGB imaging system for mapping of skin chromophores consists of a commercial RGB CMOS sensor, RGB LEDs ring-light illuminator and orthogonally orientated polarizers for reducing specular reflectance. The system was used for monitoring of vascular malformations (hemagiomas and telangiectasias) therapy.
<title>Bragg and asymmetric-relief reflection gratings in As-S-Se thin films</title>
2005
Bragg and asymmetric-relief gratings and their formation in the amorphous As-S-Se films are discussed. Due to the high refractive index and its photoinduced change, the films are useful in holography. The thickness of the As0.4S0.15Se0.45 and As0.4S0.3Se0.3 films used in the Bragg gratings is optimized. The dependence of the dimaction efficiency of the asymmetric-relief gratings on the conditions of recording, chemical treating, and reading out (polarization and angle) is studied.© (2005) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
<title>Compact multi-functional skin spectrometry set-up</title>
2006
A portable fibre-optic spectrometry set-up has been assembled and tested for applications in skin diffuse reflectance spectrometry, laser fluorescence spectrometry and multi-wavelength reflection photoplethysmography (multi-PPG) studies. The spectrometry set was tested by diffuse reflectance and fluorescence measurements for diagnostics of skin vascular malformations and pigmented diseases such as nevi and melanoma . In addition, studies of microcirculation in blood vessels located at different depths from the skin surface were performed by the multi-PPG method. The results of skin diffuse reflectance and autofluorescence showed differences in spectra of healthy and pathologic skin. The par…
Study of smartphone suitability for mapping of skin chromophores.
2015
RGB (red-green-blue) technique for mapping skin chromophores by smartphones is proposed and studied. Three smartphones of different manufacturers were tested on skin phantoms and in vivo on benign skin lesions using a specially designed light source for illumination. Hemoglobin and melanin indices obtained by these smartphones showed differences in both tests. In vitro tests showed an increment of hemoglobin and melanin indices with the concentration of chromophores in phantoms. In vivo tests indicated higher hemoglobin index in hemangiomas than in nevi and healthy skin, and nevi showed higher melanin index compared to the healthy skin. Smartphones that allow switching off the automatic cam…
Autofluorescence imaging for recurrence detection in skin cancer postoperative scars
2020
This clinical study is a first attempt to use autofluorescence for recurrence diagnosis of skin cancer in postoperative scars. The proposed diagnostic parameter is based on a reduction in scar autofluorescence, evaluated in the green spectral channel. The validity of the method has been tested on 110 postoperative scars from 56 patients suspected of non-melanoma skin cancer, with eight patients (13 scars) available for the repeated examination. The recurrence diagnosis within a scar has been made after two subsequent autofluorescence check-ups, representing the temporal difference between the scar autofluorescence amplitudes as a vector. The recognition of recurrence has been discussed to r…
Application of amorphous chalcogenide thin films in optical recording technologies
2005
A solid immersion holographic method for the recording of refractive-index and surface-relief modulated gratings with a period of 0.2 µm–1 µm in amorphous films of chalcogenide semiconductors As2S3 and As-S-Se has been developed and studied. The angular selectivity of holographic recording in amorphous chalcogenide thin films can be improved significantly by a decrease of grating period. The possibility to use the amorphous chalcogenide films as a media for holographic recording and storage of information with high density is discussed. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Agar-based phantoms for skin diagnostic imaging
2020
Agar-based skin phantoms with different thicknesses and hemoglobin concentration were evaluated for diagnostics of skin lesions by RGB imaging. Scattering properties of the phantoms were simulated using intralipid, absorption properties – using lyophilized powder of human hemoglobin. RGB images of phantoms were captured by self-developed laboratory made devices. The algorithm for calculation of chromophore concentrations are based on Beer-Lambert law and includes the photon path length evaluated from the measured photon-time-of-flight signals. Optical properties and chromophore concentration maps of phantoms obtained from RGB images were analyzed. The influence of chromophore concentration …
<title>Amorphous chalcogenide thin films as a media for holographic recording</title>
2004
The amorphous As2S3 and As40S15Se45 films as a recording media for optical holography and lithography were studied. The results on research of the transmission, surface-relief and Bragg reflection grating holographic recording and readout conditions are presented. The recording of transmission holographic gratings in As40S15Se45 films was performed by He-Ne (0.6328 μm) laser beam, while the redout of the diffraction efficiency was made at Bragg agle using diode (0.805 μm) laser lines. The Bragg reflection gratings in As2S3 films were recorded and studied by Ar+ laser line 0.5145 μm. The surface-relief modulated gratings with a period of 0.15 μm - 1 μm were recorded.© (2004) COPYRIGHT SPIE--…
Evaluation of Skin Melanoma in Spectral Range 450-950 nm Using Principal Component Analysis
2013
Diagnostic potential of principal component analysis (PCA) of multi-spectral imaging data in the wavelength range 450-950 nm for distant skin melanoma recognition is discussed. Processing of the measured clinical data by means of PCA resulted in clear separation between malignant melanomas and pigmented nevi.
Clinical evaluation of melanomas and common nevi by spectral imaging
2012
A clinical trial on multi-spectral imaging of malignant and non-malignant skin pathologies comprising 17 melanomas and 65 pigmented common nevi was performed. Optical density data of skin pathologies were obtained in the spectral range 450-950 nm using the multispectral camera Nuance EX. An image parameter and maps capable of distinguishing melanoma from pigmented nevi were proposed. The diagnostic criterion is based on skin optical density differences at three fixed wavelengths: 540nm, 650nm and 950nm. The sensitivity and specificity of this method were estimated to be 94% and 89%, respectively. The proposed methodology and potential clinical applications are discussed.
<title>Amorphous As-S-Se films for holographic recording</title>
2003
The amorphous As40S15Se45 films as recording media for optical holography were studied. The results on research of transmission and Bragg grating holographic recording and readout conditions are presented. The recording of transmission holographic gratings was performed by He-Ne (0.6328 μm) or Kr+ (0.6764 μm) laser beam, while the readout of the diffraction efficiency was made at Bragg angle using He-Ne (0.6328 and 1.15 μm) or diode (0.805 μm) laser lines. It is shown that self-enhancement of Bragg grating reflectors is possible. The influence of thin film interference conditions on holographic recording parameters is demonstrated.© (2003) COPYRIGHT SPIE--The International Society for Optic…
Towards direct measurements of remitted photon path lengths in skin: kinetic studies in the range 520-800 nm
2019
Skin-remitted picosecond laser pulses have been detected at variable input-output fiber distances (8 … 20 mm) in the spectral range 520-800 nm, with subsequent analysis of the pulse shape changes. Transfer functions representing the temporal responses of remitted photons to infinitely narrow δ-pulse excitation have been calculated. Parameters related to the photon path length in skin – input-output pulse peak delays, pulse FWHM, travel times of the “initial” photons and distributions of the remitted photon path lengths – are presented and analyzed. The measurement results are in general agreement with the photon propagation model expectations
Holographic recording optimization in amorphous As-Se-S films
2003
The holographic recording parameters of amorphous chalcogenide semiconductor (AChS) thin films under optimization depend on hologram type. So, using self-enhancement effect during recording and wet etching after recording enable possibility to decrease recording energy and increase of signal/noise ratio for embossed holograms. Choosing the appropriate light exposure permit us to achieve equal values of diffraction efficiency (DE) for different diffraction orders during fabrication of light splitting holographic optical elements (HOE). Changing film thickness and recording wavelength it is possible to find optimal conditions for high DE holographic gratings readable at infrared region of lig…
<title>Relief holographic recording in amorphous As-S-Se</title>
2003
The relief-phase holographic gratings in amorphous As-S-Se thin films were recorded and studied. The holographic recording was performed by He-Ne laser (0.6328 μm). The influence of etching and cohernet self-enhancement processes on the formation of surface relief in amorphous As-S-Se thin films was studied.© (2003) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Investigating different skin and gastrointestinal tract (GIT) pathologies ex vivo by autofluorescence spectroscopy and optical imaging
2017
The skin neoplasias are on a second place in the world statistics of cancer incidence, and gastrointestinal tract (GIT) tumours are also in the “top ten” list. For the most of cutaneous and gastrointestinal tumours could be obtained better prognoses for patients, if an earlier and precise diagnostics procedure is applied. One of the most promising approaches for development of improved diagnostic techniques, is based on optical detection, and analysis of the signatures of biological tissues for detecting the presence of pathological alterations in the investigated objects. It is important to develop and combine novel diagnostic techniques for an accurate early stage diagnosis to improve the…
Remitted photon path length in human skin, skin phantoms and cell cultures
2020
An experimental method for remitted photon path length measurements in scattering media has been developed and tested on human skin and skin neoplasms, skin phantoms and cell cultures. The photon time-of-flight (PTOF) measurement method was used in this study, where the photon travel time was converted into path length. Remitted light signals were obtained using a picosecond broadband laser and a set of narrowband interference filters in spectral rang 520 – 760 nm. Five different distances of 1, 8, 12, 16 and 20 mm between the source and detector fibers were used. Measurements were performed at different wavelengths and distance combinations; they were taken from human skin and skin malform…
Skin chromophore mapping from multi-spectral laser line images
2020
Skin chromophore maps can be used for assessment of various skin malformations and early cancer diagnostics. Commercially available devices are bulky and expensive. We present two portable proof-of-concept device prototypes for multi-spectral laser line imaging with three (448 nm, 532 nm and 659 nm) and four (450 nm, 523 nm, 638 nm and 850 nm) wavelength laser illumination. Laser modules and special optics that ensure uniform light distribution over the region of interest have been exploited. Skin chromophore maps were calculated using Beer-Lambert law, considering light scattering properties in the skin and including photon path length evaluated from the directly measured photon-time-of-fl…
Multispectral imaging of pigmented and vascular cutaneous malformations: the influence of laser treatment
2010
The paper investigates influence and efficacy of laser therapy on pigmented and vascular cutaneous malformations by multispectral imaging technique. Parameter mapping of skin pigmented and vascular lesions and monitoring of the laser therapy efficacy are performed by multispectral imaging in wavelength range 450-700nm by scanning step - 10nm. Parameter maps of the oxyhemoglobin deoxyhemoglobin and melanin derived from the images are presented. Possibility of laser therapy efficacy monitoring by comparison of the parameter maps before and after laser treatment has been demonstrated. As both cutaneous pigmented and vascular malformations are commonly found lesions, the parameter mapping would…
Kontakta un bezkontakta difūzās refleksijas spektrometrija ādas patoloģiju novērtējumam
2011
Elektroniskā versija nesatur pielikumus