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Revisiting Barrett's Esophagus || Endoscopic Treatments: Photodynamic Therapy
摘要： Photodynamic therapy (PDT) is a technique developed in 1990 for reducing the severity of tumor symptoms and cancer size. It acts through a non-thermal mechanism utilizing the activation of a photosensitizer—administrated by intravenous, topical, or oral route—with a specific wavelength of light. The excited photosensitizer generates oxygen radicals which induces localized necrosis and cellular damage in the site of photoactivation. Site and depth of injury depended on several factors, including oxygen concentration, type of sensitizing agent, waiting time between dosing and light stimulation, energy per unit area, intensity of light dosimetry, wavelength, and time of irradiation. PDT may be used in the tissues accessible to light exposure, such as skin, retina, bronchial tree, and the gastrointestinal tract, for either palliative approach (namely lumen obstruction by lung and esophageal tract cancer) or curative therapy. In the gastrointestinal tract, PDT is thought to be effective in the treatment of Barrett’s esophagus with high-grade dysplasia. Further investigational applications include palliative approach to unresectable cholangiocarcinoma and treatment of duodenal or colon adenomas associated to FAP syndrome. Finally, there are few data on ablation of gastric superficial tumors. This review focused on PDT tools, indications, limits, and contraindications in the treatment of Barrett’s esophagus.
关键词： Light,Barrett’s esophagus,Gastrointestinal tract,Photosensitizer,Photodynamic therapy
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Thin-Barrier Strained Quantum Well Superlattice Solar Cells
摘要： Cancer diagnosis is based on visual examination under a microscope of tissue sections from biopsies. But whereas pathologists rely on tissue stains to identify morphological features, automated tissue recognition using color is fraught with problems that stem from image intensity variations due to variations in tissue preparation, variations in spectral signatures of the stained tissue, spectral overlap and spatial aliasing in acquisition, and noise at image acquisition. We present a blind method for color decomposition of histological images. The method decouples intensity from color information and bases the decomposition only on the tissue absorption characteristics of each stain. By modeling the charge-coupled device sensor noise, we improve the method accuracy. We extend current linear decomposition methods to include stained tissues where one spectral signature cannot be separated from all combinations of the other tissues’ spectral signatures. We demonstrate both qualitatively and quantitatively that our method results in more accurate decompositions than methods based on non-negative matrix factorization and independent component analysis. The result is one density map for each stained tissue type that classifies portions of pixels into the correct stained tissue allowing accurate identification of morphological features that may be linked to cancer.
关键词： quantification,gastrointestinal tract,prostate,microscopy,image restoration,Blind source separation
更新于2025-09-19 17:13:59
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PET imaging in adaptive radiotherapy of gastrointestinal tumors
摘要： radiotherapy is a cornerstone in the multimodality treatment of several gastrointestinal (gi) tumors. Positron-emission tomography (PeT) has an established role in the diagnosis, response assessment and (re-)staging of these tumors. Nevertheless, the value of PeT in adaptive radiotherapy remains unclear. This review focuses on the role of PeT in adaptive radiotherapy, i.e. during the treatment course and in the delineation process.
关键词： gastrointestinal tract,Positron-emission tomography,radiotherapy
更新于2025-09-04 15:30:14