Applying the ALARA Principle in Everyday Dentistry Practices
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ALARA is an acronym for “As Low As Reasonably Achievable” as defined by the Code of Federal Regulations 10 CFR 20.1003. This principle refers to the efforts taken to ensure that exposure to ionizing radiation is minimized, and is often referenced when determining the appropriate dosing limitations for radiation workers and patients. The National Council on Radiation Protection and measurements set specific guidelines for dental practices in 2003. These requirements were updated in 2009 to better protect patients and staff from the potential cancer risks indicated to stem from cumulated low doses of ionizing radiation over long periods of time. Features of the ALARA Principle The specific principles of the ALARA system will vary based on the nature of the work that is to be done. The general philosophy requires that any office that regularly uses radiation technology during examinations actively seek out methods to minimize the dosing and exposure for patients, doctors and staff. Altering everyday practices while handling any radiation sources or materials can help to bring an office within the requirements of the ALARA principle. How the ALARA Principle is Utilized This philosophy is the backbone of the Linear No Threshold Hypothesis that determines that there is no type of radiation which is safe. Given this assumption, the harmful effects of radiation increase with the dose. As a result of this it is strongly encouraged that all populations that are regularly exposed to radiation be protected from as much of this exposure as possible. Exceptions are made within reason if radiation exposure is necessary for medical procedures such as X-rays or if exposure is simply unavoidable. • Dental schools are required to include reticular collimation in training and student teaching courses to meet requirements of the ALARA principle. • Any positioning devices should reduce the chances of cone cutting during the procedure. Interactive Diagnosing Imaging is recommended for X-ray procedures. • Specific dental practices will need to follow regulations set by national and regional safety organizations in order to remain licensed and certified in the field. Social, Technical and Economic Considerations If unlimited funding were available it would be possible to further decrease radiation dosing. However, limitations in funding and technology limit the feasibility of many of these techniques. Other options such as forbidding potentially life-saving examinations because of the potential radiation exposure would not be acceptable to society. These considerations are taken into account when any ALARA requirements are imposed on industry standards. ICRP Regulations The International Commission on Radiological Protection (ICRP) recommends implementing the ALARA principle in three phases. • Any proposed activity that may expose persons to radiation must offer benefits that outweigh the potential risks. This is also known as the linear, nonthreshold hypothesis (LNT). • Any radiation used during a procedure must be optimized, or implemented in the lowest doses reasonably achievable. Most licensing agencies including the Nuclear Regulatory Commission (NRC) require the ALARA principle to be implemented in this manner. • Finally, an upper limit on dosing must be set for any member of the public that will in contact with man-made exposures to radiation. NCRP Regulations The NCRP has established a mandatory six step process that allows dental practices to conform to radiation guidelines. • All round X-ray collimators must be replaced with rectangular collimators to reduce the effective radiation dosage for patients without negatively impacting the image quality during the examination. • The fastest speed film possible must be used during all imaging tests along with the fasted image receptors available. • All patients exposed to radiation must be shielded with a leaded apron. Children must always be provided a thyroid shield and adults must be offered this shield when it will not interfere with the examination. • Personal dosimeters must be worn by all pregnant employees and carefully monitored to ensure their safety while X-ray equipment is in use. • Any shielding devices used in a dental office must be certified by the existing state regulatory departments. These must allow the doctor to maintain communication and visual contact with the patient and allow the doctor to maintain a 2-meter distance from the tube head during radiation exposure. If a 2-meter distance cannot be maintained, you must install a barrier shield. Implementation Recommendations Dental regulations set by the National Council on Radiation Protection and Measurements note that dentists have a legal, professional and moral obligation to limit the exposure of their patients and staff to ionizing radiation as much as possible. There are two mandatory steps that must be taken in order to comply with the minimum requirements for dental practices. • All X-ray collimators (cones) should be replaced with rectangular collimators. This will not have an effect on the image quality these machines can produce, but will reduce the effective dose of radiation the patient would be exposed to by four to five. • Dental practices must use the fastest imaging receptors available. Any means of reducing radiation dosage such as incorporating phosphor plate technology or direct digital sensors should be considered. If you are using traditional film, an F speed minimum can reduce radiation dosage by 20 percent and E speed film can reduce this dosage by 50 percent when compared to D speed film. Applying the ALARA Principle to Everyday Dental Work There are some general portions of the ALARA program which must be applied to any industry that uses radiation-producing machines or radioactivity. All facilities must display a strong commitment to managing radiation at all levels of the facility and throughout your organization. In layman’s terms this means that all individuals present in the facility must receive equal protection from radiation exposure. All program procedures including education and training programs must also meet the requirements of the Radiological Safety Committee. These practices will be regularly audited to ensure that the radiation reduction programs used in the office are sufficient and in line with current industry standards. ALARA Considerations During Equipment Decontamination Any internal or external methods applied to reduce radiation doses during decontamination of products must be in line with ALARA principles. They must also be able to reduce the waste produced during the decontamination process. While there are specific guidelines in this category, it is understood that not all methods will be appropriate for use on a particular surface or radionuclide. Annual auditing will allow dental practices to learn more about which decontamination methods will be most appropriate for their setup. The Validity of the “No Safe Dose” Assumption The idea that there is no safe dose of radiation is commonly debated throughout the scientific community. There is a great deal of evidence that suggests that radiation is quite dangerous, but it is implied that there may in fact be a safe dosing level for humans. However, until a safe dose can be accurately defined, the ALARA principle will remain in effect to minimize any potential risks. Radiation Source Reduction Radiation source reduction refers to the idea of reducing your dose rate that is administered over time. There are several methods available to help businesses such as dental practices that regularly use radiation as part of their work achieve these goals. Installing processing and filtration equipment that will help to capture radioactive sources before they will reach the patients or staff can be a means of achieving this goal. Removing any nonessential radioactive equipment or materials from the office is also a means to minimize radioactivity exposure. This will limit the amount of radioactivity that can deposit on surfaces. Flushing or draining systems that may contain radioactive fluids and ventilating areas where radioactivity may exist are also essential safety procedures. Other Source Reduction Methods If it is more practical, radionuclide sources can be allowed to decay through their half-life cycle. This is only applicable to materials that have a relatively short half-life. Containment, Ventilation and Filtration Subsets of the ALARA principle require practices to manage radiation exposure by controlling containment, ventilation and filtration options. • Controlled-opening or leak-tight enclosures must be used to prevent radioactive materials from migrating to unwanted areas. These enclosures may be temporary which will allow you to remove them after the job is complete if it would be less expensive or allow you to make better use of limited space. • Ventilating air flow and the flow of other cases through an area where there is airborne radioactive particles is necessary to remain ALARA compliant. This may require capturing gasses and pushing them through collection filters before they are released back into the atmosphere to allow the office to meet ventilation requirements. This helps to ensure that any people in the immediate area are exposed to a minimal dosage of radioactivity while radioactive machinery is in use. • Filtration or filtering specifically refers to capturing airborne radioactive particles on a medium such as a vacuum cleaner back so that they can be disposed of according to outstanding regulations. • Ventilated fume hoods, exhaust systems, glove boxes, water filtration systems, double-walled pipes or takes, leak-tight valves and other systems may be used to better confine radioactive materials.