
Jean Shubert Nelson- Université du Québec en Abitibi-Témiscamingue
Jean Shubert Nelson
- Université du Québec en Abitibi-Témiscamingue
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125
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Introduction
Current institution
Publications
Publications (125)
Time-resolved infrared images are used to form tomographic reconstructions of laser-heated cutaneous chromophores. In-vitro and in-vivo experiments are reported and discussed.
Erythrocyte-based nanoparticle platforms can offer long circulation times not offered by traditional drug delivery methods. We have developed a novel erythrocyte-based nanoparticle doped with indocyanine green (ICG), the only FDA-approved near-infrared chromophore. Here, we report on the absorption and fluorescence emission characteristics of these...
We propose a novel application of optical coherence tomography (OCT) to monitor pit formation in laser-irradiated optical storage materials. A multilayer optical storage recordable compact disk is composed of multiple layers, each of different structure. The disks were irradiated with a Q-Switched Nd:YAG laser with an energy of 373 mJ. Post-irradia...
Optical coherence tomography (OCT) is a new modality capable of cross sectional imaging of biological tissue. Due to its many technical advantages such as high image resolution, fast acquisition time, and noninvasive capabilities, OCT is potentially useful in various medical applications. Because OCT systems can function with a fiber optic probe, t...
We simulate temperature depth profiling in human skin using pulsed photothermal radiometry (PPTR). By taking into account blackbody emission characteristics, spectral variation of human skin IR absorption coefficient, detectivity of available radiation detectors, and shot noise, we compute realistic PPTR signals for a test temperature profile, repr...
We describe a novel scheme for complete suppression of polarization-dependent loss/gain (PDL, PDG) for transmission-type optical devices (LPG, SOA) via a λ/2-shifted all-fiber Sagnac loop interferometer. The results are explained theoretically and demonstrated experimentally.
The accurate noninvasive assessment of traumatic wound depth and serial evaluation of wound healing is an active and ongoing research goal. A large number of noninvasive modalities have been evaluated including the use of vital dyes, indocyanine green dye fluorescence, fluorescein fluorometry, laser Doppler flowmetry (LDF), thermography, ultrasound...
In cutaneous vascular laser surgery, hemoglobin and melanin are important skin chromophores that influence treatment of port wine stain (PWS) birthmarks. A potential problem in quantitative chromorphore evaluaton is the error in image analysis associated with a number of factors, including nonuniform illumination and skin curvature. In this study,...
Monitoring dynamic changes during laser induced photothermolysis of vascular skin lesions is essential for obtaining an optimal therapeutic result. Rapid photoinduced thermal damage occurs at a threshold temperature of about 70 degrees C. It is therefore, relevant to identify markers to indicate if this threshold temperature has been reached. Methe...
Cryogen spray cooling (CSC) is a spatially selective heat transfer technique that provides epidermal protection dur- ing laser treatment of selected dermatoses, such as port wine stain (PWS) birthmarks. Most numerical studies of CSC-assisted PWS therapies to date assume constant cooling conditions at the skin surface. In the present study, however,...
A novel polarization-sensitive optical coherence tomography (PS-OCT) system was developed using polarization maintaining (PM) optical fibers and fiber coupler to measure birefringence properties of samples. Polarization distortion due to PM fibers and coupler can be calibrated with different polarization states during two consecutive A-scans. By pr...
The purpose of this study was to evaluate the ability of single and dual wavelength excitation pulsed photothermal radiometry (SWE- and DWE-PPTR, respectively) to profile port wine stain (PWS) skin. To this end, a numerical optical-thermal model was developed, incorporating a digitized PWS biopsy as the input skin geometry. Both SWE and DWE reconst...
The influence of depth dependent dispersion by the main component of biological tissues, water, on the resolution of OCT was studied. Investigations showed that it was possible to eliminate the influence of depth dependent dispersion by water in tissue by choosing a light source with a center wavelength near 1.0 µm. Ultrahigh resolution ophthalmic...
We demonstrate a novel application of optical coherence tomography (OCT) to monitor post-laser irradiation collagen injury in model skin. An artificial skin model (RAFT), which closely approximates human skin, was irradiated with a Perovskite laser (λ=1341 nm), which is under investigation for potential use as a nonablative laser skin rejuvenation...
Cryogen spray cooling (CSC) is used extensively for epidermal protection during laser-induced photothermolysis of port wine stains and other vascular skin lesions. The efficacy of CSC depends critically on the heat transfer coefficient (H) at the skin surface for which, however, no reliable values exist. Reported values for H, based on tissue phant...
YM Wang YH Zhao Hongwu Ren- [...]
ZP Chen
We developed an ultrahigh resolution optical coherence tomographic system utilizing broadband continuum generation from a photonic crystal fiber for high axial resolution. Longitudinal resolution of 1.3 gm has been achieved in a biological tissue by use of continuum light from 800 to 1400 run as the light source. The system employed a dynamic focus...
Cryogen spray cooling (CSC) has been used along with pulsed lasers for nearly a decade to irreversibly photocoagulate a variety of vascular lesions. However, the fundamental mechanisms that take place at the skin surface are still incompletely understood. In this work, we built a fast-response temperature sensor with the objective to determine the...
Cryogen spray cooling (CSC) is used to minimize the risk of epidermal damage during laser dermatologic surgery. During CSC, skin surface is cooled by a short spurt of refrigerant R134a with boiling point of −26.2°C. Since R134a is volatile in open atmospheric conditions, the atomized liquid droplets undergo continuous evaporation as they fly in air...
Cryogen spray cooling (CSC) has been used for selective epidermal
cooling of human skin during laser therapy of patients with port wine
stain (PWS) birthmarks. Unfortunately, current commercial CSC devices do
not provide optimal cooling selectivity and, therefore, provide
insufficient epidermal protection for some PWS patients. To assist in
the dev...
Phase-resolved optical Doppler tomography (ODT) has very high
sensitivity while maintaining a fast axial scanning rate, making it
possible to reconstruct blood flow in three dimensions. Here we
demonstrate an ODT system that employed novel signal-processing
techniques to remove aliasing effects and artifacts caused by lateral
scanning and target mo...
Cryogenic sprays are used for cooling human skin during selected laser treatments in dermatology. In order to optimize their cooling efficiency, a detailed characterization and understanding of cryogen spray formation is required. Various instruments and procedures are used to obtain mean size (D), velocity (V), and temperature (T) of tetrafluoroet...
Optical Doppler tomography (ODT) combines laser Doppler flowmetry with optical coherence tomography to obtain high-resolution images of blood flow in human skin in situ and in real time.
We present a case in which ODT was used on a patient with a port-wine stain (PWS) birthmark to document the change of blood flow in response to laser therapy. It m...
Recent studies have indicated that chondrocyte viability decreases with prolonged or repeated laser irradiation. To optimize laser-mediated cartilage reshaping, the heating process must be finely controlled. In this study, we use high-power Nd:YAG laser irradiation (lambda = 1.32 microm) combined with cryogen spray cooling (CSC) in an attempt to re...
. Port wine stains (PWS) are congenital vascular malformations for which lasers are the treatment of choice. This article
reviews laser optics in relation to PWS treatment and discusses the major laser and light source systems, including the flashlamp-pumped
pulsed dye laser (FLPDL), cryogen spray cooling in combination with the FLPDL, the potassiu...
Cryogenic sprays are of interest in dermatology for cooling human skin during pulsed laser treatment of port wine stain (PWS) birthmarks. In the present study, a Phase Doppler Interferometer (PDI) was used to obtain preliminary measure-ments of mean diameters and mean velocities of tetrafluoroethane (HFC-134a) spray droplets, generated by an atomiz...
A phase resolved OCT/ODT system was developed to image tissue microcirculation. This technique uses phase change between sequential scans to construct flow velocity images with high imaging speed, while maintaining high spatial resolution and velocity sensitivity
Summary form only given. Recent development of optical coherence tomography (OCT) has shown great promising applications for noninvasive and contactless imaging of subsurface soft tissues. However, better image quality and greater depth of penetration are always advantageous for clinical applications. A new 8-channel array detecting optical coheren...
To demonstrate feedback-controlled laser-mediated cartilage reshaping using dynamic measurements of tissue optical properties and radiometric surface temperatures.
Flat cartilage specimens were reshaped into curved configurations using a feedback-controlled laser device.
Fresh porcine nasal septum, stripped of perichondrium and cut into uniform str...
In many port wine stain (PWS) patients, successful clearing is not
achieved even after multiple laser treatments because of inadequate heat
generation within the targeted blood vessels. Use of higher radiant
exposures has been suggested to improve lesion clearing, but risk of
epidermal injury due to nonspecific absorption by melanin increases. It
h...
Laser radiation can be used to reshape cartilage tissue into new
morphologic configurations. When a critical temperature is attained,
mechanically deformed cartilage becomes malleable and may be reshaped
into new geometric configurations that harden as the tissue cools. This
temperature dependent process results in mechanical stress relaxation
and...
We demonstrate a method for infrared tomographic imaging of the
initial three-dimensional (3-D) temperature increase of in vivo blood
vessels following pulsed laser exposure. Using a time-sequence of
infrared images recorded by a fast focal plane array camera as input
data, a reconstruction algorithm is used to compute the initial 3-D
temperature i...
Vascular responses were monitored to understand the role of the
microvasculature in tumor destruction as a result of photodynamic
therapy (PDT). Rats received an intravenous dose of 2 mg/kg
Benzoporphyrin Derivative (BPD), at 20 min, 4 h, or 7 h before laser
irradiation. With Photofrin (10 mg/kg), drug-light intervals were 20 min
or 8 h. Jejunal bl...
Optical Doppler tomography (ODT) is an imaging modality that takes
advantage of the short coherence length of a broad-band light sources to
perform micrometer-scale, cross-sectional imaging of tissue structure
and blood flow dynamics simultaneously. The authors review in this paper
the principal of ODT and its applications. Results from in vitro an...
A polarization-sensitive optical coherence tomography (PSOCT)
system was used to acquire depth-resolved images of the Stokes
parameters of light backreflected from ex vivo rabbit eyes. The light
backreflected from the eye interferes with that from the reference arm
and is coherently detected in two orthogonal polarization channels. The
two signals...
Summary form only given. Optical Doppler tomography (ODT) is a recently developed imaging modality that combines laser Doppler flowmetry with optical coherence tomography (OCT) to obtain high resolution tomographic images of static and moving constituents in highly scattering biological tissues. We have previously demonstrated noninvasive in vivo i...
Presents measurements of port wine stain skin radiometric surface temperature in response to laser irradiation in conjunction with cryogenic spray cooling, internal temperature reductions obtained within an epoxy-resin skin phantom, and temperature predictions within human skin
Real-time measurements of diffuse reflectance from backscattered HeNe laser light (λ=632.8 nm) and radiometric surface temperature can be used as input to a feedback procedure to control the process of laser mediated cartilage reshaping. A prototype device for reshaping cartilage was constructed using modulated laser irradiation emitted from an Nd:...
Burn depth assessment is a key step in guiding the treatment plan in patients who have sustained thermal injuries. We have developed a technique, polarization sensitive optical coherence tomography (PS-OCT), to provide the physician with a quantitative estimate of actual burn depth. We generated burns of various depths by contacting rats with a bra...
Carbon dioxide (CO2) laser resurfacing has been used as a method to treat rhytides and photodamaged skin. This laser offers several advantages over previously utilised modalities but its use has several inherent risks. This article will review important aspects of CO2 laser resurfacing including laser-skin interactions, patient selection, effective...
A three-dimensional Tomographic Reconstruction Algorithm (3D TRA) has been developed and implemented on a parallel machine at the Maui High Performance Computing Center (MHPCC). Given a time sequence of infrared images, this algorithm provides information to determine the location, physical dimensions, and initial space-dependent temperature increa...
Cartilage undergoes characteristic mechanical stress relaxation following laser irradiation below the ablation threshold. Porcine auricular cartilage (1–2 mm thickness) was irradiated with a Nd:YAG laser (=1.32 m) at two power levels (W/cm2). Surface temperature (S
c
(t) (C)) (monitored using a single element HgCdTe infrared detector, 10-14 m spec...
Progress is reported on the development of pulsed photothermal tomography (PPT) for determination of the initial three-dimensional temperature increase in biological materials immediately following pulsed laser irradiation. PPT uses a fast infrared focal plane array (IR-FPA) to detect temperature rises in a substrate, induced by pulsed radiation. T...
Block-detection and three-dimensional moment algorithms are applied to determine the presence and orientation of cylinders in a three-dimensional image. The proposed method detects blood vessels in a three-dimensional tomographic image constructed by infrared radiometry. Based on the moment principle, the method can be employed to determine the cen...
In the last decade, Q-switched lasers have expanded the clinician’s ability to treat decorative, cosmetic and traumatic tattoos
without scarring. Previous methods of gross tissue removal with resultant scarring have been replaced by the highly selective
removal of tattoo pigment with minimal changes in skin texture or pigmentation. This article rev...
The epidermal melanin content affects most dermatologic treatments involving light, and can limit the therapeutic success
significantly. Therefore, knowledge of the optical properties of skin is required. This study investigates how the concentration
of melanin influences visible reflectance spectra of skin and the relationship to threshold radiant...
A unique Monte Carlo program capable of accommodating an arbitrarily complex geometry was used to determine the energy deposition in a true port wine stain anatomy. Serial histologic sections taken from a biopsy of a dark red, laser therapy resistant stain were digitized and used to create the program input for simulation at wavelengths of 532 and...
A comparative study of human skin thermal response to (1) contact cooling with a sapphire window and (2) spray cooling with various cryogens is presented.