Visualization of body parts in motion by projecting x-rays on a luminous fluorescent screen is known asGroup of answer choicesConventional RadiographyComputerized tomographyFluoroscopyUltrasonography

visualization through x-ray beam

Computed Tomography (CT) is a medical imaging technique that uses X-rays to obtain structural and functional information about the human body.The digital geometry processing can be used to generate a three-dimensionalimage of the internal structures of the human body from a large series oftwo-dimensional X-ray images taken around a single axis of rotation

Which of the following techniques estimates body composition by scanning the body with the two low-energy x-rays?Multiple ChoiceAir displacementBIAUnderwater weighingDXA

Tomography is imaging by sections. By aquiring multiple 2-D images from multiple , a 3-D image may be reconstructed with the aid of a tomographic reconstruction applied by a computer. The device used to produce the images is called a tomograph, while the image produced is a tomogram. Several different tomographic methods are used in modern medicine for purposes. Of particular interest to us are techniques which use radionuclides. In SPECT ( photon computed tomography), the patient is injected with a that decays by gamma-ray emission. These gamma rays are detected by a camera, forming an image of the distribution of the in the body of the patient. Another tomographic method that uses radionuclides is PET ( emission ). In this method, the radionuclide which is injected decays by (positive beta-particle) emission. It does not take long for the positron to collide with an , anihiliating each other, producing two that travel off in (generally) opposite directions. These of gamma-rays are then detected by the PET scanner.

X-ray imaging requires the use of harmful ionizing radiation to image structures inside the body.  An x-ray image intensifier, shown in Figure 1, allows high-quality imaging with very low radiation exposure to the patient.Figure 1  Schematic of an x-ray image intensifierThe x-ray image intensifier amplifies the imaging signal by approximately 300,000 times.  The intensifier converts the image data from x-ray photons to visible light, then to electrons, and back to visible light.  At each conversion stage, the signal is amplified up to 1,000 times.The x-ray image intensifier consists of a vacuum chamber that contains an input phosphor, a photocathode, focusing electrodes (not shown in Figure 1), an anode, and an output phosphor.  The anode voltage is 25 kV higher than the photocathode, generating a strong electric field in the vacuum.  The input phosphor converts x-ray photons into visible light, which then ejects electrons from the photocathode.  Even with an anode voltage of 25 kV, no current will flow through the vacuum unless electrons are ejected from the photocathode.  Ejected electrons are accelerated toward the anode and focused onto the output phosphor.  At the output phosphor, the electrons are converted back into visible light, allowing image data to be recorded with a camera or video system.  (Note:  Use c = 3 × 108 m/s in a vacuum, if needed.)Question 30Is the vacuum chamber in an x-ray image intensifier an electrical insulator?A.Yes, because only electrons ejected from the photocathode can travel through the vacuum chamberB.Yes, because no electrons can travel through the vacuum chamberC.No, because electrons can travel through the vacuum chamber even without x-rays at the input phosphorD.No, because electrons in the vacuum chamber are not exposed to a voltage difference