Radiology

DENTAL X-RAY TUBE The dental X-ray tube is surrounded by a glass envelope that houses a vacuum. The glass prevents low-grade radiation from escaping. The vacuum insures the protection of the equipment from catastrophic failure. Production of X-rays generates enormous amounts of heat; the vacuum prevents the risk of combustion and ensures the proper environment for conduction of electrons. There are two separate energy sources, one that powers the energy poten…

RELATIVE RADIO SENSITIVITY OF THE TISSUES Radiosensitive (2500 r or less kills or seriously injures many cells) Lymphocytes and lymphoblasts Bone marrow (myeloblastic and erythroblastic cells) Epithelium Germ cells (testes and ovary) Radioresponsive (2500-5000 r kills or seriously injures many cells) Epithelium of skin and many appendages. Endothelium of blood vessels Salivary glands Growing bone and cartilage. Conjunctiva, cornea and lens of eye …

Radiation Biology -X- and g -rays are called sparsely ionizing because along the tracks of the electrons set in motion, primary ionizing events are well separated in space. Alpha-particles and neutrons are densely ionizing because the tracks consist of dense columns of ionization. X-rays, gamma rays, electrons, and protons are all low LET forms of radiation in that their density of ionization is sparse. In general, they penetrate tissues deeply and result i…

Digital Radiology Advances in computer and X-ray technology now permit the use of systems that employ sensors in place of X-ray ?lms (with emulsion). The image is either directly or indirectly converted into a digital representation that is displayed on a computer screen.  DIGITAL IMAGE RECEPTORS - charged coupled device (CCD) used - Pure silicon divided into pixels. - Electromagnetic energy from visible light or X-rays interacts with pixels to creat…