BACKGROUND: Photobiomodulation therapy (PBMT) is recommended for the prevention of oral mucositis (OM) in cancer patients. Transcutaneous, extraoral delivery of PBMT with LED arrays, versus intraoral delivery with laser, may be more effective for treatment of at-risk sites and better tolerated by patients. The objective was to develop an evidence-based extraoral PBMT treatment protocol.
METHODS: We previously demonstrated that Monte Carlo modeling accurately simulates in vivo transmittance measurements. Archival MRI studies (n=18) were used to determine anatomical structures along the trajectories of 850 nm light through the cheek, lip, mandible angle and neck. Optical properties of skin, fat, muscle, cartilage, and blood were obtained from literature, and Monte Carlo modeling was performed for skin types I and VI. Simulation results were used to determine the treatment time needed to deliver a median dose between 1 and 6 J/cm2 to the mucosa.
RESULTS: Cheek had greatest variability in thickness (13-29 mm) corresponding to a 25-fold difference in the mucosal fluence rate. Despite tissue differences, fluence attenuation is primarily determined by the overall thickness of all tissue
The goal of this study was to investigate how nano-channels created by laser irradiation can affect the diffusion properties of cartilage. Nano-channels were created using a 400 µm fiber optic and a 1550 nm laser. Optical polarization images confirmed the creation of nano-channels. Samples were placed in a homemade diffusion chamber, containing CuSO4 solution and distilled water in the donor and recipient chambers, respectively. T1 weighted MR images were taken over several time points and processed to analyze the rate of diffusion through each sample. Peak diffusion occurred at 24 hours for treated samples and 48 hours for native samples. At 24-hours, diffusion rate was approximately 50% higher in treated samples. At 72-hours, diffusion rate was 9% higher in treated samples. Our results highlight that laser treatment could improve treatment of diseases and injuries of cartilage. Optical confocal imaging is underway to investigate the microscopic morphology of the treated samples.
In this work, we evaluated the acoustic and optical properties of silk protein-based hydrogels to investigate its potential as a phantom material. Acoustic properties include the speed of sound and acoustic attenuation of silk scaffolds at various concentrations. Optical properties include optical absorption and reduced scattering measured between 400 nm to 1200 nm to coincide with common photoacoustic imaging bandwidths. The results indicate that silk is an acceptable phantom material for ultrasound and photoacoustic systems as it inherently displays similar acoustic properties and reduced scattering as various tissue types while displaying low absorption.
The goal of this study was to analyze temperature dependent changes in NIR reflectance of ex vivo freshly excised human skin. A broadband halogen lamp was used as a light source. Remitted light was collected using an optical fiber and analyzed by a grating spectrometer. Samples were heated to and maintained at temperatures up to 60°C using a temperature control unit. The temperature was also independently monitored using a thermal camera. Consistent changes found include blue shift in water absorption peaks. This method may prove to be useful for monitoring tissue temperature during clinical procedures in real time.
Skin cancer is the most common human malignancy. The goal of this pilot study was to validate a novel handheld optical polarization imaging (OPI) device for preoperative detection of basal cell carcinoma (BCC) margins. Ten patients with biopsy proven basal cell carcinoma (BCC) were imaged prior to Mohs surgery at UMASS Memorial Medical Center. Preliminary results from analysis of 10 BCC lesions show a strong correlation between optical imaging and histopathology. These findings indicate OPI may be a valuable tool for optimizing surgical treatment of skin cancer.
The goal of this study was to develop reliable technique for measuring optical properties of renal calculi. As the first step, the technique was tested on artificial (Bego) stones. Absorption coefficients and reduced scattering coefficients of samples at 1940 nm were evaluated from total transmittance and diffuse reflectance measurements using an Inverse Monte Carlo technique. Optical properties were determined before and after soaking samples in distilled water. Before soaking, samples had absorption coefficients of 0.12±0.03 /mm, and reduced scattering coefficients of 7.72±2.34 /mm. After soaking, absorption coefficients were 0.21±0.04 /mm, and reduced scattering coefficients were 8.53±3.90 /mm. Future studies aim to determine optical properties of natural stones.
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