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Understanding Light in Optical Microscopy
Published in John Girkin, A Practical Guide to Optical Microscopy, 2019
At the core of all optical imaging methods is light, and the image seen through a microscope is a result of the way that light interacts with the sample. This chapter outlines the physical principles that underpin optical microscopy without the requirement for a high level of physics expertise. Initially the basic concepts of light are presented; this is followed by an explanation of how optical components manipulate light to provide high quality microscopy images. Optics are not always perfect, and some of the complications in manipulating light and how this can lead to images that are poor in quality, crucially lacking the detail required to understand the processes being studied, are also discussed. However, even the best possible optics will provide no suitable images without contrast, or the ability to highlight the areas of interest from the background. A range of standard contrast mechanisms is therefore explained, illustrating how the different properties of light presented earlier are used to enhance the features of interest in an image. The chapter then finishes by looking at the two ends of an optical microscopy system, the light source and the detector. Throughout the chapter as new terms are introduced these are explained with the minimal use of mathematical formulation. Where applicable the mathematical explanation for a specific process is provided in a text box, but this detail can be bypassed without the reader becoming lost in later explanations. The full physical details can be found in any standard optical textbook (Hecht 2015; Born and Wolf 1999).
Future Directions: Opportunities and Challenges
Published in Sarhan M. Musa, ®, 2018
On the other hand, optical imaging per se or in combination with other modalities such as positron emission tomography (PET), single-photon emission tomography (SPECT) magnetic resonance imaging would offer the potential for noninvasive or minimally invasive exploration of molecular targets inside the human body [73,74]. Optical imaging in combination with other modalities and appropriate nanotechnology tools would allow the characterization of a variety of diseases, such as breast cancer, skin cancer, lung cancer, cancer of the bladder; the study of drug effects on the target pathology and drug treatment effects; the development of biomarkers and molecular contrast agents indicative of disease and treatment outcomes; and the analysis of molecular pathways leading to diseases.
Advances in Patient Setup and Target Localization
Published in Siyong Kim, John Wong, Advanced and Emerging Technologies in Radiation Oncology Physics, 2018
Optical imaging tracks the patient surface movement using either infrared markers such as the Exactrac system (Brianlab, Inc), or optical surface imaging such as AlignRT (VisionRT, Inc), Catalyst (C-RAD), and Identify (humediQ). In the infrared marker–based system, several infrared markers are placed at noncoplanar locations on the patient surface. A set of infrared cameras mounted in the room tracks the locations of the markers to determine the patient motion and location. The optical-based surface imaging system uses three ceiling-mounted cameras and a patterned light in order to reconstruct 3D surface data of the patient’s body. During the treatment planning session, the system acquires a reference image when the patient is in the optimal position. When the patient is treated, a new image is taken and matched to the original reference image to determine the patient displacement in real time. Limitations of optical imaging techniques are that they require open skin surface, and they can only track the patient surface motion, which may not be fully correlated with the internal target motion (Figure 7.4).
Improving Three-Dimensional Near-Infrared Imaging Systems for Breast Cancer Diagnosis
Published in IETE Journal of Research, 2023
Yasser Noori Shirazi, Abdolreza Esmaeli, Mohammad Bagher Tavakoli, Farbod Setoudeh
The optical phenomena and its non-invasive properties have made optical imaging system as powerful tool in medical studies, including in the imaging of tissues. Light dispersion causes to increase the track length of light in the tissue, thus resulting in increasing absorption probability of light. All incidents are elastic, and the direction of reflected photons depends on the dimensions of scattered particles, wavelength, and refraction coefficient of medium that light travels in it. Amplitude modulation of light produced by laser diodes is used as light source whose wavelength is 800 nm. Carrier frequency of this signal is 100 MHz. It is found completely in simulations that by changing the location of the sources and the detectors, better results are obtained both observationally and quantitatively. In this paper, it is observed that by placing sources and detectors in our suggested location, abnormal area can be diagnosed 21% more accurate than previous work. Thus, obtaining a more accurate diagnosis and a higher-resolution image in 3-D images reconstruction of the breast tissue by near-infrared lights depends on the accurate location of the sources and the detectors. In addition, the correct diagnosis of two abnormal areas was examined where the coordinates of their locations in some axes were different. The use of this design can help significantly in better diagnosis of breast cancer by means of NIR Imaging. The considered subject in this research, namely type of placement of near-infrared light sources and detectors for more correct diagnosis of breast cancer can be extensively the field of other researchers in the future. Furthermore, researchers can perform valuable research studies from this approach in the field of diagnosis of bleeding, neural activity examination, and photographing the newborn baby’s head.
A review on synthesis and applications of versatile nanomaterials
Published in Inorganic and Nano-Metal Chemistry, 2022
G. N. Kokila, C. Mallikarjunaswamy, V. Lakshmi Ranganatha
Diagnosis in the medical field is the process of determining which disease or condition explains a patient’s symptoms and signs. Many diseases like Parkinson disease, Creutzfeldt-Jakob disease, Alzheimer’s diseases, Amyotrophic Lateral Sclerosis, Atherosclerosis, cancer, and other prion diseases are diagnosed by different techniques such as magnetic resonance imaging (MRI), computed tomography (CT), ultrasound (US), optical imaging (OI), and photoacoustic imaging (PAI), as well as positron emission tomography (PET) and single-photon emission computed tomography (SPECT). These diagnosis techniques are performed on their unique principles and strategies and also have certain disadvantages. Diagnosis using MRI has some disadvantages like low sensitivity to contrast agents, require high costs, and consume more time. CT shows insufficient soft tissue contrast without injection of contrast agents, exposure to radiation may bring health issues and it also shows low sensitivity to contrast agents. Ultrasound diagnosis is user-dependent and not usually used to whole-body imaging. Optical imaging has drawbacks like low penetration depth, show high background signal, and sensitivity to artifacts. PET and SPECT have limitations as they have a low spatial resolution, low anatomical information, radiation exposure leads to health complications, and requires high cost.[265] Therefore, new diagnosis methods or improved existing diagnostic tools are be developed to overcome the above problems.[266,267] Sometimes traditional diagnostic tools can not differentiate between infected tissue and healthy tissue and cannot detect the early stages of the disease. This may increase the patients’ health risk and mortality. The diagnostic demands on nanoparticles rely on a rapid and highly site-specific contrast enhancement. Diagnostic nanoparticles focus on detecting pathogens, infectious tissue, and help to grasp the disease symptoms mechanism, assist in their proper treatment, and offer early stopping of disease. Using a small number of patient samples gives increased sensitivity and selectivity to detect small local, distant diseases cells compared to conventional assay using nanotechnology in diagnosis.
Overview of the application of inorganic nanomaterials in breast cancer diagnosis
Published in Inorganic and Nano-Metal Chemistry, 2022
Asghar Ashrafi Hafez, Ahmad Salimi, Zhaleh Jamali, Mohammad Shabani, Hiva Sheikhghaderi
Optical imaging is a wide keyword that covers all imaging with ultraviolet, non-ionized visible as well as infrared electromagnetic waves.[75] This is a noninvasive imaging technique that is currently using visible light (400–700 nm) and near infrared (NIR) wavelengths (700–1000 nm) to probe morphological, molecular, and functional information of the tissue and for scattering, fluorescence, and absorption properties. Achieve information at the metabolic and molecular levels. In other words, optical imaging modalities can produce images of both tissue function and microscopic structures is one of the advantages of optical imaging.[76–78] Additionally, some methods in OI technique involve endoscopy, optical coherence tomography (OCT),[79–81] photoacoustic imaging, diffuse of optical tomography (DOT),[82,83] Raman spectroscopy (RS),[84,85] super resolution microscopy (SRM)[86,87] and terahertz tomography (TT).[88] To point out, OI technique can measure various phenomena such as scattering, adsorption, auto-fluorescence, fluorescence and photoacoustic.[78]Figure 1 illustrated some specific molecular reagents utilized as the contrast agent in OI technique. Significantly, those agents comprise besides the endogenous tissue optical contrast, exogenous tissue contrast agents, non-targeted optical contrast agents, cancer biomarkers and targeted probes.[89] The contrast agent was employed in OI technique for imaging of the cancer cells because the light absorption and propagation properties in the tissues depended on this contrast agent. The contrast agent was employed in OI technique for imaging of the cancer cells because both light absorption and propagation properties in tissues depended on it.[7] On the positives side, OI approach was carried out not only without the use of destructive ionizing radiation but also in the least time possible and it was applied wildly for the detection of the soft tissues as they could either adsorption light or scatter. Finally, as OI is compared with others, radiological imaging techniques have a several capabilities e.g., this technique is able to take the image structure in the broad range of the type and size of IO technique, so that it can couple with other techniques.[89]