Since their discovery, the use of X-rays has always been indispensable in the field of medicine and dentistry. Radiological investigations play a pivotal role in diagnosis, management and treatment planning. Be it simple procedures like the diagnosis of caries or something complex like the placement of implants, radiographic examinations are of utmost importance. High radiation doses result in cell death, whereas low doses cause damage or alteration of the DNA of irradiated cells.
All healthcare professionals are trained for radiation hazards and the required safety measures are imparted, but it needs to be assessed as to how sincerely this knowledge is imparted towards the patients. No practice or source within the practice should be authorized unless the practice produces sufficient benefit to the exposed individuals or to society to offset the radiation harm that it might cause; that is: unless the practice is justified, taking into account social, economic and other relevant factors
All living things are exposed to ionising radiation from the natural (called background radiation) and man-made radiation sources. Ionising radiation may cause biological changes in the exposed person hence the doses to the occupational workers shall be kept “As Low As Reasonably Achievable” (ALARA) and doses to patients shall be optimized. Suitable control measures shall be employed to minimise radiation exposure so that maximum benefits are derived with minimum radiological risk. The normal exposure of individuals resulting from all relevant practices should be subject to dose limits to ensure that no individual is exposed to a risk that is judged to be unacceptable.
These particles are found in the atom, which is the smallest part of any material. When the energy of the radiation is high enough, it can remove electrons from the atoms or molecules of a substance and is called ionizing radiation. Not all electromagnetic radiation causes ionization. Ionizing radiation can pass through materials, and is also called penetrating radiation. X rays and gamma rays are high-energy ionizing EM radiations and may simply be called “radiation.”
Radiation causes ionization. Penetrating radiations are useful in the diagnosis and treatment of diseases and are part of the backbone of modern medicine. However, because radiation can ionize and excite molecules, it can cause damage to living tissues. Therefore, we must take precautions when using and working around it.
Not all radiation interacts with matter in the same way. Radiation that has enough energy to move atoms in a molecule around or cause them to vibrate, but not enough to remove electrons, is referred to as “non-ionizing radiation. Examples of this kind of radiation are sound waves, visible light, and microwaves.
Radiation that falls within the ionizing radiation range has enough energy to remove tightly bound electrons from atoms, thus creating ions. This is the type of radiation that people usually think of as ‘radiation.’ We take advantage of its properties in diagnostic imaging, to kill cancer cells, and in many manufacturing processes. Examples of non-ionizing radiation exposures in the clinical setting include: Magnetic resonance imaging (MRI), ultrasound and LASERS.
X rays are identical to gamma rays; however, they are produced by a different mechanism. X rays are an ionizing radiation hazard. A typical radiation dose from a chest x-ray is about 10 mrem. A typical radiation dose from a whole-body CT is about 1500 mrem.
Medical Sources of Radiation
Diagnostic sources include x-ray machines and radioactive materials. X-ray machines are used in radiography and fluoroscopy, and they may be permanently installed (“fixed”) or mobile. Radiation protection methods are employed to reduce radiation exposure to the patient and others. In radiography, the exposure time is very short, usually less than one second, and x rays are emitted from the machine only when the control switch to the unit is turned ON by the operator, Personnel is typically not in the x-ray room during the time the x rays are being emitted.
Fixed X-Ray Machines
These are primarily located in the X-Ray or Radiology Department, but they may be located in other areas of the hospital, such as operating rooms and emergency rooms. These x-ray machines are used in the diagnosis of disease. These are located in a specially shielded room and are typically operated by personnel trained in the proper use of the equipment.
Portable or Mobile X-Ray Machines
Mobile x-ray machines are similar in function to the fixed machines; however, they are mobile and are transported to the patients who cannot be moved. Mobile machines are typically used to examine patients in the Operating or Recovery Room during or after surgery, trauma victims in the Emergency Room, patients located in intensive care units, neonatal units, and other bedridden patients. Personnel and other patients may receive a small amount of exposure to x rays during the time that the x-ray machine is on. Personnel who assist in holding patients should wear protective aprons, as should the operator.
Radioactive materials used in nuclear medicine are radioactive liquids, capsules containing radioactive materials, or gases. These radioactive materials may be administered intravenously to patients, or are swallowed or inhaled by them, to obtain an image of a particular organ or body system. Radioactive materials continually emit radiation and cannot be turned off. The patient is temporarily radioactive until the radioactive material decays to an acceptable level or is eliminated naturally by the body. Consequently, body fluids from these patients also can be radioactive, and appropriate precautions should be taken in handling them (e.g., normal nursing procedures such as wearing rubber gloves).
Some laboratories use small amounts of radioactive material for “in vitro,” or test tube, diagnostic tracer studies. The amounts of radioactive material used are typically only a fraction of those used in nuclear medicine studies and generally do not pose any radiation risk as long as proper procedures are followed.
Radiation Therapy Machines
Radiation therapy machines are located in heavily shielded rooms in the radiation therapy or radiation oncology departments. These machines deliver high doses of radiation for the treatment of cancer and other diseases.
The Basic Principles of Radiation Protection
External contamination occurs when radioactive material, in the form of dust, powder, or liquid, comes into contact with a person’s skin, hair, or clothing. In other words, the contact is external to a person’s body. People who are externally contaminated can become internally contaminated if radioactive material gets into their bodies. Internal contamination occurs when people swallow or breathe in radioactive materials, or when radioactive materials enter the body through an open wound or are absorbed through the skin. Some types of radioactive materials stay in the body and are deposited in different body organs. Other types are eliminated from the body in blood, sweat, urine, and faeces.
Protection Against Radioactive Material Contamination
Contamination is the undesirable presence of radioactivity, such as a liquid spill on the floor, or clothing. It is a potential hazard whenever unsealed radioactive materials are present. Avoid contaminating an area. Contamination can spread radioactivity to outside areas, including cars and homes, and can result in the accidental ingestion or inhalation of radioactive materials. Prevent contamination by using the same precautions followed when handling infectious agents, and biological and chemical substances. Wear rubber gloves and protective clothing. Because the radioactive contamination emits radiation, one must practice the protection methods described in the previous section. Remember that radioactivity or contamination cannot be seen. Radiation detecting instruments are used to survey when contamination is suspected.