PROTECTING STAFF AND PATIENTS USING PROPER RADIATION SHIELDING FROM SCATTER
X-rays Improve Patient Outcomes but Safety Measures Required to Reduce Radiation Exposure for Patients and Staff
X-rays have been a boon to medical science, providing detailed diagnostic and therapeutic value to practitioners that improve patient outcomes dramatically. However, the harmful effects of radiation exposure to the human body cannot be overemphasized. Medical practitioners, dental professionals, radiologists, technicians, and other healthcare workers who administer ionizing radiation, especially in the form of X-rays, are commonly exposed to radiation directly or indirectly during the procedure. Despite the inherent hazards, the benefits outweigh the risks considerably. It is important to be familiar with the magnitude of radiation exposure and the measures that can be taken to safeguard staff and patients, including wall shielding, room shielding such as mobile barriers and curtains and wearable protection.
Dental Offices Perform Nearly Half a Billion X-rays Annually Exposing Patients and Staff to High Levels of Radiation
Dental X-rays are used to detect and diagnose a wide range of oral conditions from periodontal disease and decay to TMJ, cysts and tumors. Digital imaging has indeed revolutionized dentistry by providing the ability to quickly diagnose a condition and formulate a treatment plan.
However, it comes at a heavy cost in the form of increased exposure to ionizing radiation for both patients and staff. According to the report of The United Nations Scientific Committee on Effects of Atomic Radiation, approximately 480 million diagnostic radiographs are performed in dentistry alone worldwide every year, which comprise 15% of all diagnostic X-rays in healthcare. Radiation doses are low for individual examinations, however, the cumulative effect for patients and staff can reach dangerous levels. It is important to employ methods that can attenuate exposure and decrease radiation dosage, especially from scattered radiations.
Annual Radiation Exposure Should Be Kept to As Low As Reasonably Achievable
The National Council on Radiation Protection(NCRP) and International Commission on Radiological Protection (ICRP) have stipulated that for whole-body radiation, exposure of not more than 12.5mSv (1,250 mRem) ionizing radiation dose per quarter, or 50mSv (5,000 mRem) per year can be considered to present minimal risk and must not be exceeded. Pregnant women should not exceed 5mSv(500 mrem) during her entire gestational period.
However, every effort should be made to keep the dose of ionizing radiation to all individuals as low as possible. All unnecessary radiation exposure should be avoided. This philosophy of radiation protection is based on the ALARA principle which translates as- As Low As Reasonably Achievable, and emphasizes the possibility that no matter how small the dose, some adverse health effects may occur.
According to the American Dental Association, the effective radiation dose for dental radiographic examinations is 0.005-0.171mSv, depending on the type of exam and number of images captured. While this amount is well below the maximum exposure of 12.5mSv, all precautions should be exercised to follow the ALARA principle to minimize the risk of exposure to ionizing radiation.
Ionizing Radiation Exposure Linked to Cancer, Birth Defects and Leukemia
X-Rays cause biological changes in living cells and adversely affect all living tissues. The effects of ionizing radiation can be extremely damaging. Various hereditary effects and serious diseases are linked to exposure from medical imaging procedures including, but not limited to, leukemia, breast, lung, thyroid and other cancers, and irradiation in utero leading to birth defects, mental retardation and childhood cancer.
Radiation Protection Guards Patients and Staff from Unsafe Doses
To minimize the radiation exposure, the as low as reasonably achievable (ALARA) principle should be strictly followed along with continuous monitoring of radiation exposure with radiation badges or dosimeters. The International Commission on Radiological Protection (ICRP) recommends a maximum safe limit for an effective dose of 20 mSv/year (averaged over a defined 5-year period with no single year exceeding 50 mSv) for the whole body.
With the use of proper patient protection techniques, the amount of X-ray received by the patient can be minimized. In dental radiography, clinicians must use every means to reduce unnecessary exposure to their patients, themselves and staff. This can be done with the help of wall shielding, room shielding such as mobile barriers and curtains and wearable protection in the form of lead aprons, collars, etc.
Lead aprons offer considerable protection from radiation exposure, but this personal protective equipment may not cover the entire body. The weight of lead aprons can be a cause of discomfort and may cause occupational injuries with prolonged use.
Lead and Lead-Free Room Shielding is the Most Effective Radiation Barrier
Lead radiation barriers are a highly effective way to provide a full-body shielding barrier. X-Ray room shielding in various forms is considered to be the most effective way of limiting scattered radiation in a dental office. Shielding, as the name suggests, is a means to have a barrier that absorbs radiation present between the source of the radiation and the area to be protected. Hence, radiation shielding provides a barrier between the operator and the source of the radiation.
Radiation shielding is based on the principle of attenuation, which is the gradual loss in intensity of any energy through a medium. Whenever an x-ray beam passes through matter the intensity of the beam decreases and is absorbed by the material. Lead performs this beam attenuation perfectly, acting as a barrier to reduce the scattered radiation by blocking the x-ray photons when they collide with lead. The greater the thickness of lead shielding around a radiation source, the smaller the exposure. A heavy and dense lead shield is necessary to absorb high-energy radiation, decreasing scatter and protect against the energy emitted from x-rays.
Lead-free alternatives are also available for radiation shielding, offering equal protection from scatter. Lead-free room shielding is lightweight, non-toxic and environmentally friendly.
Radiation Shielding Protects Patients, Staff and Surrounding Office Personnel from Exposure
Three sources of radiation must be shielded; (1) primary (the x-ray beam), (2) leakage (from the x-ray source or tube) and (3) scattered or secondary.
X-Ray room design and shielding are a critical consideration for any healthcare center that performs radiological procedures regularly. Dental offices should be designed and constructed to meet the minimal shielding requirements of The National Council on Radiation Protection (NCRP).
Using X-ray room shielding protects:
- Patients: Protect patients who are being examined and those in surrounding treatment areas or in the waiting area.
- Operating personnel: The technician or nurse positioning the x-ray and the operators. NCRP reiterates that every effort should be made so that the operator can leave the room or take position behind a lead barrier.
- Other staff, visitors and the general public present in the x-ray area.
- Where the x-ray room shares a wall with another office, shielding is essential.
X-Ray Shielding Guidelines
For intraoral x-rays in the dental office, a protected position behind a barrier or six-foot distance is required for the operator. NCRP recommendations state that walls must be of sufficient density or thickness that exposure to non-occupationally exposed individuals (e.g. someone occupying an adjacent office) is no greater than 100 mGy per week. Walls constructed of gypsum wallboard (drywall or sheetrock) are adequate for the average dental office.
Additional shielding (three thicknesses of drywall instead of two) is recommended when sharing a wall with another office or tenant. Double thicknesses of drywall should be used in the dental office when doing up to 100 exposures per week and triple thickness when performing up to 150 exposures per week. Leaded glass radiation protection windows can be installed in these walls to safely view patients while remaining behind a safe barrier.
Panoramic X-ray units which incorporate a film holder and a beamstop and do not normally require shielding. They may be placed in any location which allows the operator to maintain a four-foot distance from the patient while using the machine. Of course, access to the area must be limited while the unit is in use.
Dental machines shared by two rooms should have the pass-through opening located at the foot-end of the rooms so the primary radiation cannot pass directly through the opening. Doors on this pass-through are recommended, not as a specific regulation, but as an extension of the regulations requiring either distance or shielding.
Mobile Barriers, Lead Curtains and Leaded Glass Provide Protection from Scatter Radiation
When walls and lead barriers are not feasible, there are other options for shielding like leaded glasses and lead drapes, as well as mobile and stationary lead barriers between the patient and staff, reducing exposure to scatter radiation.
Mobile radiation barriers include lead barriers with or without leaded glass viewing windows. The advantage of a mobile barrier is that wheels on the bottom of the shield barrier allow easy movement of the shield. Portable barriers can be moved to any area where the X-ray is to be performed, saving space in the dental office.
Leaded X-ray glass permits doctors and technicians to watch the patient safely throughout procedures, while remaining behind the barrier, enabling safe shielding against X-ray radiation. The glass has high lead and barium content, providing optimum shielding against radiation from equipment operating in the 80 to 300 kV range.
Mobile lead shields of at least 0.25 mm lead equivalency are recommended to be used during radiology procedures. These come in a wide variety of shapes and sizes to suit your imaging needs. Research studies have shown that the amount of radiation reaching the personnel can be drastically reduced using a mobile shield barrier. Moreover, some studies also observed that there was no significant difference between radiation doses from the inside of the mobile shield barrier, and that reaching the inside and outside of the personal protective equipment. This proves that these radiation barriers can be equally effective in blocking radiation as that of lead aprons.
X-Rays curtains made from leaded rubber sheets are an effective solution for shielding healthcare workers against scattered radiation from X-ray devices while saving space. Being able to stand directly behind lead curtains will diminish the scattered radiation thus serving as a barrier between the healthcare worker and the radiation produced from the X-ray device. Although no direct comparison with other shielding devices has been performed, the theoretical advantage of a bigger size of any barrier like lead curtains (having greater surface area) is that it will be able to shield scattered waves from more diverse angles and ranges.
X-Ray curtains also provide privacy to the patient by separating the working area from the rest of the treatment area and office. They are particularly valuable in offices that do not have a separate X-ray room, helping you to separate the rest of the dental office and shield other staff and patients present and not working on radiographs, from unnecessary and inadvertent exposure to radiation. Since the curtains can be retracted at will, they help customize the X-ray room according to needs.
Protective equipment and shielding devices should be used appropriately to lower the radiation exposure by as much as possible. It is crucial to take every measure to reduce the potential hazards of working with radiation while designing your dental clinic. Investing in durable, state-of-the-art and effective radiation shielding can greatly improve the quality of care for your patients while offering protection and peace of mind to clinicians and staff.
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