Tag: Medical imaging
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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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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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The Function of a PET scan in Biomedical Diagnostics
The radionuclides that are employed in a PET scan as part of radiopharmaceuticals work best when used for imaging certain physiological properties. Combined with a CT scan or an MRI, a PET scan is good for locating things such as tumours. As a matter of fact, a PET scan can light up for the brain,…
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Comparison of Imaging Modes – Ultrasound, CT & MRI
How the three imaging modalities compare? We examine each of the three diagnostic imaging methods as discussed in the following sections: Ultrasound Imaging Unlike other imaging modalities, ultrasound resolution and penetration depends on the center frequency and type of frequency selected. The resolution is spatially variant and depends on both the size of the active…
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The Process of Setting up a PET scan
The ability of a PET scanner to target specific functions or objects e.g. tumour makes it a very effective tool in non-invasive medical imaging and diagnostics. The process involves using radionuclides, so PET scanners aren’t available at every medical facility. Related: Radionuclide Imaging Techniques The process of setting a PET scan involves the following steps:…