precautions while using x rays

Precautions while using X Rays

X-rays are forms of radiant energy,medical procedures, x-rays are safe when used with care.
41. SHEILDING
On installation, primary consideration should be given to ensure each tube is protected by fixed shielding. Reliance should not be placed on protective aprons and other shielding worn by the person using the system. Emplaced shielding is the most effective mechanism of protecting workers from unnecessary x ray exposure. Always operate these systems with all shielding and safety components in place; never tamper with system interlocks.
42. Analytical X ray Systems
Analytical x ray machines (e.g., x ray diffraction, etc.) are used extensively for microstructure analysis in various research and teaching activities. Tubes for this purpose usually operate about 35 40 kV and 10 40 mA. In such equipment, the primary x ray beam is permitted to impinge on the specimen and the scattered radiation is measured by a radiation detector located at various angles with respect to the sample.
43. Precautions and Guidelines
Get proper training/instruction from the person in control before operating x ray producing machines. Never assume the unit was left in a safe working condition by the previous user, check the shielding before turning the unit on. Unless a pre operational check was made, do not trust the warning lights when they are not lit. To check the light s operability, set the unit to its lowest kV and mA setting and check the warning lights and interlocks. Do not bypass any safety device or interlock without the approval of the person in control of the machine. In such cases, post a sign stating Safety Device Not Working. Return the system to its unmodified state with all interlocks operational as soon as possible.
44. Shielding should always be adequate
Shielding should always be adequate so other factors need not be required for safety. However, exposure reduction techniques include, increasing your distance from the x ray source, increasing shielding, and decreasing the time spent near the x ray source. Do not work near the open, unshielded beam. However, if it is necessary to work near the unshielded radiation beam (e.g., for system alignment): Reduce the beam current (mA) and the beam energy (kV) to the lowest settings possible to reduce exposure rates. Keep hands and body at a safe distance from the beam by using appropriate alignment tools.
45. Analytical X ray Equipment Radiation Safety Requirements
X ray producing devices at UWM are regulated by the State of Wisconsin, Department of Health and Family Services (DHFS), Radiation Protection Section. All applicable regulations and safety requirements should be adhered to whenever working with x ray producing equipment. Some of the most important safety requirements are: A safety device must be provided which prevents entry of any part of an individual s body into the primary x ray beam path or which causes the beam to be shut off immediately upon such entry.
46. Properties
X ray photons carry enough energy to ionize atoms and disrupt molecular bonds. This makes it a type of ionizing radiation, and therefore harmful to living tissue. A very high radiation dose over a short amount of time causes radiation sickness, while lower doses can give an increased risk of radiation induced cancer. In medical imaging this increased cancer risk is generally greatly outweighed by the benefits of the examination. The ionizing capability of X rays can be utilized in cancer treatment to kill malignant cells using radiation therapy. It is also used for material characterization using X ray spectroscopy.
47. Interaction with matter
X rays interact with matter in three main ways, through photoabsorption, Compton scattering, and Rayleigh scattering. The strength of these interactions depend on the energy of the X rays and the elemental composition of the material, but not much on chemical properties since the X ray photon energy is much higher than chemical binding energies. Photoabsorption or photoelectric absorption is the dominant interaction mechanism in the soft X ray regime and for the lower hard X ray energies. At higher energies, Compton scattering dominates.
48. Photoelectric absorption
The probability of a photoelectric absorption per unit mass is approximately proportional to Z3/E3, where Z is the atomic number and E is the energy of the incident photon. This rule is not valid close to inner shell electron binding energies where there are abrupt changes in interaction probability, so called absorption edges. However, the general trend of high absorption coefficients and thus short penetration depths for low photon energies and high atomic numbers is very strong. For soft tissue photoabsorption dominates up to about 26 keV photon energy where Compton scattering takes over. For higher atomic number substances this limit is higher. The high amount of calcium (Z=20) in bones together with their high density is what makes them show up so clearly on medical radiographs.
49. Compton scattering
Compton scattering is the predominant interaction between X rays and soft tissue in medical imaging. Compton scattering is an inelastic scattering of the X ray photon by an outer shell electron. Part of the energy of the photon is transferred to the scattering electron, thereby ionizing the atom and increasing the wavelength of the X ray. The scattered photon can go in any direction, but a direction similar to the original direction is a bit more likely, especially for high energy X rays. The probability for different scattering angles are described by the Klein
50. Rayleigh scattering
Rayleigh scattering is the dominant elastic scattering mechanism in the X ray regime.The inelastic forward scattering is what gives rise to the refractive index, which for X rays is only. X rays can be very penetrating. The voltage of the system indicates how penetrating the x rays will be. The higher the voltage of the generator, the more penetrating the radiation. Just like gamma rays, x rays interact with molecules in the body to produce ion pairs.