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## D9. CH-9-X-Ray-M.Phys. ### 3- What are contrast dye or agents for X-ray imaging? Radiocontrast dyes or agents are substances used to enhance the visibility of internal structures in X-ray imaging such as computed tomography (contrast CT), projectional radiography, and fluoroscopy. The contrast d...

## D9. CH-9-X-Ray-M.Phys. ### 3- What are contrast dye or agents for X-ray imaging? Radiocontrast dyes or agents are substances used to enhance the visibility of internal structures in X-ray imaging such as computed tomography (contrast CT), projectional radiography, and fluoroscopy. The contrast dye can be an iodine-based material, barium-sulfate, gadolinium, or saline-air mixture that can be swallowed or injected intravenously. Contrast distinguishes, or "contrasts," between organs, tissues, bones, or blood vessels during your imaging exam. ### 4- What are the 4 types of contrast media? Here are the four types of contrast media and relative contrast compounds: * Oral Contrast Media. * Intravenous Contrast Media. * Rectal Contrast (enema) Media. * Microbubble (intravenous) Contrast Media. ### 5- Where is contrast media used? Contrast media (sometimes called contrast agents or dye) are chemical substances used in medical X-ray, magnetic resonance imaging (MRI), computed tomography (CT), angiography, and occasionally ultrasound imaging. * **Penumbra:** is the amount of unsharpness of the image so penumbra is the area of partial shadow. * **Umbra:** is the area of total shadow and it exists only when the object absorb all X-rays. * **Grids:** are placed between the patient and the X-ray film to reduce the scattered radiation reaching the detector (produced mainly by the Compton effect) and thus improve image contrast. * **Intensifying screen:** converts the x-ray energy into light, which reaches the film and forms the latent image. In dentistry, this type of film is used in panoramic imaging and cephalometric radiography.