Radiation Hazards – Dental radiographs are considered specific area radiographs as they are taken of small areas and not the whole body. There is no absolutely safe dose of radiation; any amount causes damage. The amount of radiation hazards received affects the severity of the damage done—the higher the dose, the more damage. The effects of radiation are cumulative. Today’s effect is added to yesterday’s effect, and tomorrow’s effect will be added to today’s effect, and so forth throughout life. The radiation hazards due to Overexposure is known to be a consistent cause of cancer. Naturally occurring radiation exposure is added to medical/dental exposure.
All radiations are ionizing in nature. All cells in body grow and divide, forming new cells. When a change happens, the cells work together over time to bring everything back into balance. Ionizing radiation hazards breaks the cell bonds and disturbs the balance of the cell. In an effort to regain normalcy, atoms combine with other disturbed atoms, thereby forming a new substance. This substance may be harmful to the cell or organ that was struck by the X-rays. The amount of radiation hazards that’s done is directly related to two factors: the time in the life of the cell that exposure occurs and the type of cell or tissue involved in the exposure.
The most sensitive time for a cell is when it is dividing to form two new cells. This cell division is called mitosis. Radiation hazards are severe when it is done to the cell if it is irradiated during mitosis. The type of tissue involved in the exposure is important because each cell has a different rate of mitosis. Radiosensitive and radioresistant are the terms used to describe the degree of sensitivity each type of tissue has. Tissues that have a fast rate of reproduction are said to be radiosensitive, or more sensitive to radiation. Those that have a slower rate of change are said to be radioresistant, or more resistant to damage. Cells that reproduce rapidly, such as the human embryo and reproductive cells, are most radiosensitive and least radioresistant. Cells that do not change very much after they have fully formed, such as enamel or bone cells, are least radiosensitive and most radioresistant.
Radiation hazards has two effects on tissue or cells: the direct effect and the indirect effect. The direct effect occurs when the nucleus of the cell is directly hit by radiation, making the cell to die immediately. In the treatment of cancer, the aim of radiation hazards is to have a direct effect on the cancer cells so they die quickly before spreading. The indirect effect occurs when cells are changed in a destructive manner. This often occurs in the case of the reproductive cells. Unfortunately, damage may not be evident for a long time. The number of cells indirectly affected or killed determines the amount of damage done and how much the function of the cells or organ is altered.
Radiation hazards can be somatic or genetic. Somatic effects are seen in all areas of the body except in the genetic tissue. Remember, radiation hazards accumulate in the body. The first signs of radiation ifiness are changes in the blood. For changes in the blood to occur, the entire body would have to be overexposed to radiation. It would take a large dose at one time for this to occur. Dental X-rays cover specific small areas. The whole body is not directly exposed, and the dental machine is not capable of producing the amount of radiation hazards necessary for somatic effects.
Genetic effects include damage done to reproductive cells that can be passed on and may not be evident for several generations. For this reason, it is important to follow all the safety measures and never overexpose your patients or yourself to radiation hazards.
Effects of overexposure are short term or long term. Short-term effects occur with high doses of radiation hazards over a short period of time, such as in cancer therapy. The long-term effects occur with both high doses over a short term and small doses over a long term. Genetic diseases are the effect of small doses over a long term. The radiation worker must be protected from small doses over a long period of time.
STAGES OF EFFECT OF radiation hazards
There are three stages of radiation hazards:
1. Latent period. It is the period from the time of exposure until the effect is seen. The first sign of overexposure to radiation is erythema or redness of the skin.
2. Short-term effects. Seen within a week of exposure.
3. Long-term effects. Seen in years or decades or even in the next generation.
The radiation hazards on cells are cumulative. Whatever damage is done during a first exposure is added to damage from the next exposure, and so on. if exposures are extensive (cover a large area) and not much time passes between exposures, the cells do not have time to correct themselves. In the case of the cancerous tumor, this is good because it is eventually destroyed. if good tissue around the tumor is also destroyed, it is not good. The destruction of tissue is both the benefit and hazard of radiation hazards.
Between exposures, the body tries to return to normal. Seventy-five percent of the cell damage is repaired within 24 hours. Repair continues over time at this same rate. So on the first day, 75 percent of the whole damage is repaired; on the second day, 75 percent of the remaining 25 percent of damage is repaired; and by the third day, 75 percent of the remaining 6.25 percent of damage is repaired; and so on. This is assuming that the cells are not subjected to more radiation hazards. There have been only few incidents reported about radiation hazards caused by dental X-rays. There are always minor risks, but the information gained in the diagnosis of dental disease or even medical conditions in oral tissues far outweighs the risks. Today, better equipment and other innovations allow very little radiation hazards.
MEASUREMENTS OF RADIATION EXPOSURE
Several different terms are used to measure ionizing radiation hazards. Researchers have defined a unit of radiation exposure as 1 roentgen, or 1 R. One R involves the scientific measurement of the amount of X-radiation hazards required to change a very tiny amount of air at standard conditions of temperature and pressure. A unit of radiation that enters the body is called a radiation absorbed dose (rad). The effect of that unit on the body is called relative biological effect (RBE). Scientists combined these measurements to describe the roentgen equivalent in man (rem), which is the physical and biological effect of various amounts of radiation on tissue. Using rem measurement, scientists have been able to adopt a maximum permissible dose (MPD) for the purpose of radiation hazards safety.
The National Council on Radiation Protection and Measurements (NCRPM) in the United Sates and similar organizations in most of other countries, have established limits on how much radiation hazards an operator can be exposed to. The recommended limits are 0.3 R per week, 3.0 R per 13 week period, and 5.0 R per year.
Dental offices or hospital are supposed to provide all the auxiliary staff involved with radiology process, a monitoring badge called Dosimeter badge, which measures any exposure to X-rays so that the limits won’t be exceeded. The badges are collected every 13 weeks and sent to a radiology laboratory for processing, and then a report is sent back. If there is any evidence of exposure, corrective measures in radiation hazards safety techniques should be taken. Equipment should also be inspected to see if there is a leak in the area of the machine where radiation hazards is produced.
Radiation hazards SAFETY
Manufacturers built safety measures into the modem x-ray machines. These include aluminum filters and a lead lining, which are used to absorb rays that could harm tissue. A lead shield is also added to the x-rays films. Older units should be inspected to be sure there are no leaks in the tube head or elsewhere.
In addition of the above mentioned safety measures, some precautions taken while exposing the radiographs can restrict the amount of radiation hazards harm for both the patients and the operator.
PROTECTING THE X-RAY MACHINE OPERATOR
• Never hold the film in the patient’s mouth.
• Never stand in the path of the primary beam used to take the radiograph.
• Stand six feet behind the tube head, behind a lead screen, or out of the room.
• Have equipment inspected regularly.
• Wear a monitoring badge (Dosimeter Badge).
SAFETY MEASURES TO PROTECT THE PATIENT FROM RADIATION
Sufficient protection of the patient from the radiation hazards is also of great importance in modem dental offices. Some of the safety measures, which should be followed in all the dental offices, while exposing the patients to radiation hazards, during the process of taking the radiographs, are as follows:
• Use of a lead apron with a cervical collar.
• Ask the patient about any recent medical radiation therapy.
• Make sure that unnecessary radiographs are not being taken.