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Imaging Modalities in Medical Diagnostics

   

Added on  2020-04-13

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Running head: IMAGING MODALITIES1Imaging ModalitiesProfessor’s Name:Name:Date:
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IMAGING MODALITIES2X-RAYSDEFINITION: An imaging technique that uses ionizing x-rays radiation to create an image of the internal body structures of a patient.HISTORY: X-ray radiography is the oldest form of medical imaging. X-rays were discovered by Roentgen in 1895. He noticed that a cathode ray tube exposed a paper coated with barium compound placed at a distance. PHYSICAL PRINCIPLES: X-rays are generated in a cathode ray tube (x-ray tube). A beam of electrons generated from the cathode is accelerated towards a metal disk (anode) by a high voltage current. Upon impact, the kinetic energy of the electrons is transformed into x-rays. The X-rays are passed through the body and captured by a detector placed behind the patient. The detector is usually a photo-sensitive film or a digital detector. Absorption of x-rays in the body varies, with dense bones absorbing more radiation and soft tissue allowing most radiation to pass through. This variation produces a contrast in the image, giving a 2D representation of the internal structures of the patient.Medical Applications:Chest: to examine the lungsSkeletal: examination of bone structure and diagnosis of fractures, dislocations Abdomen: assessing abdominal obstruction, free fluid or free air within the abdominal cavity.Dental: to assess cavity and other dental pathologyAdvantages: it’s not invasive techniqueDisadvantage:organs may obscure each otherX-rays are ionizing and may damage tissues
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IMAGING MODALITIES3Computed Tomography (CT Scan)DEFINITION: Is a medical imaging technique that uses a rotating x-ray tube to take multiple x-ray projections from different angles to give detailed cross-sectional images of internal areas of the body.PHYSICAL PRINCIPLES: When an x-ray beam passes through body tissues, it is progressively weakened and the final intensity recorded on the detector. The attenuation dependson the type of tissues it passes through. For each probe, a summary effect of beam attenuation byall tissues can be obtained. Collecting many images enables the reconstruction of radiation absorption by a specific point and thus, CT scans are able to give precise identification of the examined tissues and also reconstructs organ shapes.Multiple scans of the same cross-section from different angles make it possible to create a 3-D visualization of the anatomic details of the patient.Clinical applications: imaging of soft tissues like brain,blood vessels, heart, lungs and abdomen, Diagnosis of tumorsPelvic scanAdvantages: non-invasive techniqueGives precise identification of examined body parts as there is no tissue obstruction (speedy diagnosis)Disadvantages: exposure to high doses of ionizing radiation (due to multiple scans) may damage tissues
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