Lead shielding refers to the use of lead as a form of radiation protection to radiation shield people or objects from radiation so as to reduce the effective dose. Lead can effectively attenuate certain kinds of radiation because of its high density and high atomic number; principally, it is effective at stopping and .
Because of lead's density and large number of electrons, it is well suited to scattering x-rays and gamma-rays. These rays are , a type of boson, which impart energy onto electrons when they come into contact. Without a shield, the electrons within a person's body would be affected, which could damage their DNA. When the radiation attempts to pass through lead, its electrons absorb and scatter the energy. Eventually though, the lead will degrade from the energy to which it is exposed. However, lead is not effective against all types of radiation. High energy electrons (including beta radiation) incident on lead may create bremsstrahlung radiation, which is potentially more dangerous to tissue than the original radiation. Furthermore, lead is not a particularly effective absorber of neutron radiation.
Protection of the reproductive organs with a lead rubber apron is considered important because DNA changes to sperm or egg cells of the patient may pass on genetic defects to the offspring of the patient, causing serious and unnecessary hardship for child and parents.
The thyroid gland is especially vulnerable to x-ray exposure. Care should be taken to place a lead apron over the thyroid gland before taking Dentistry radiographs.A Patient's Guide to Medical Imaging By Ronald Eisenberg, JD, MD, FACR, Alexander Margulis, MDCurrent oral and maxillofacial imaging,Thomas F. Razmus, Gail F. Williamson, Page 107 Aprons used for dental imaging should include thyroid collars. However, in poorer or loosely regulated countries, possibly due to the cost of such equipment (approx. 40 USD), no such lead protection is given to the patients themselves, though the operators do get out of the x-ray room for their own safety.
The correct thickness of lead-equivalent (Pbeq) wear will depend on how long and how often the person is working in an exposed environment. The minimum requirement is to wear 0.25 mm Pbeq when not behind lead shielding. In a theatre using fluoroscopy (e.g. orthopaedics, cardiology or interventional radiology) 0.35 or 0.5 mm lead may be appropriate because of the higher KV employed, and on proximity to the primary beam.Livingstone RS, Varghese A, Keshava SN. A Study on the Use of Radiation-Protective Apron among Interventionists in Radiology. J Clin Imaging Sci 2018;8:34
Determining the correct shielding thickness is guided by several factors, including radiation energy levels, equipment type, room layout, and adjacent occupancy. National and international standards (such as those from the NCRP and ICRP) provide calculations and guidelines for required lead equivalency.
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