Category: Biomedical Diagnostic Instruments
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What is Single Photon Emission Tomography (SPECT)?
Single Photon Emission Tomography (SPECT) is a technique for producing 3D images from 2D images of injected radionuclide in the body. The 2D image is obtained by using a device such as a gamma camera. This comprises of a large (0.5 diameter) crystal of NAI, which emits flashes of light when γ-rays impinge on it.…
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Scintillation Counters: Operation & Application in Medical Imaging
Scintillation counters are basically made up of the following main components: a scintillation material (crystal), a photodetector (photomultiplier in this case) which is used to count flashes (scintillations) from the crystal and an electronic pulse forming and pulse height discriminating circuit. The scintillation crystal is typically sodium iodide. Operation of Scintillation Counter The energy from…
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Features of Modern MRI Scanners
Magnetic resonance imaging (MRI) is a medical imaging modality which employs magnetic fields and radio waves/radiofrequency (RF) energy to produces images of the body. This imaging technique is based on nuclear magnetic resonance (NMR), which is a quantum mechanical phenomenon exhibited by atoms having either an odd number of protons or neutrons. Such atoms have…
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What is Magnetoencephalography (MEG)?
Magnetoencephalography (MEG) is a form of neuroimaging that maps the tangential components of magnetic fields associated with scalp potentials produced by the brain. These potentials are similar to those that can be recorded as electroencephalograms (EEGs) however the dynamic magnetic components of these potentials contain different information with spatial sampling. Unlike fMRI or PET images…
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What is Functional MRI (fMRI)?
Functional MRI (fMRI) is the use of MRI to detect localized changes in brain activity, usually in the form of changes in cerebral metabolism, blood flow, volume, or oxygenation in response to task activation. In other words, Functional MRI provides images of brain activity in response to various stimuli. These changes are interrelated and may…
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The Principle & Applications of Confocal Imaging
Confocal imaging (CI) is based on illuminating a single point on the sample and collecting scattered light from the same point of the sample. The illumination point on the sample is the image of the illumination pinhole and is imaged into the detector pinhole, hence making both pinholes and the illuminated spot on the sample…
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Key Features of Modern ECG Systems
Modern diagnostic and monitoring ECG acquisition and analysis systems are equipped with modern-day computer technology. ECG monitoring devices constitute an important part of the patient monitoring systems. Patient monitoring systems are used to continuously or intermittently measure the vital signs (ECG, heart rate, pulse rate, blood pressure and temperature) and perform automatic analysis on them.…
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Basic Features of Teleradiology
Teleradiology is a subcategory of telemedicine operation focusing in remote diagnosis of medical images. Teleradiology uses computer, display and telecommunication technologies for radiologists to make remote diagnosis from radiological images generated at distant examination sites. The diagnostic report is sent to the examination site where a primary physician can provide suitable treatments to the patient…
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Optical Tomographic Imaging
The optical properties of normal and diseased tissues are usually different despite the large variation of values in optical properties of the normal tissues alone. A case in point is the cancerous tissues that manifest significant architectural changes at the cellular and subcellular levels, and the cellular components that cause elastic scattering have dimensions typically…
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What is Echocardiography?
Echocardiography is a diagnostic technique that employs ultrasound to produce an image of the beating heart in real time. A piezoelectric transducer element is used to emit short bursts of high frequency, low intensity sound through the chest wall to the heart and then detect the reflections of this sound as it returns from the…