Time: Show “Time” simply refers to the amount of time you spend near a radioactive source. Minimize your time near a radioactive source to only what it takes to get the job done. If you are in an area where radiation levels are elevated,
There is no reason to spend more time around it than necessary. For an example of minimizing time, click here Distance:“Distance” refers to how close you are to a radioactive source. Maximize your distance from a radioactive source as much as you can. If you increase your distance, you decrease your dose. For an example of maximizing distance, click here Shielding:To shield yourself from a radiation source, you need to put something between you and the radiation source. The most effective shielding will depend on what kind of radiation the source is emitting. Some radionuclides emit more than one kind of radiation. For an example of using shielding, click here You can see how these principles work together when you have an x-ray at your doctor’s office or clinic. The radiation technician goes behind a barrier while taking the x-ray image. The barrier protects them from repeated daily exposure to radiation. If there is a radiation emergency, use time, distance, and shielding to protect yourself and your family. Time If a radiation emergency happens, get inside a stable building as quickly as possible. Distance How long you need to stay inside will depend on
Emergency officials will instruct you when it is safe to leave the area. Shielding If you are in a multistory building, move to the center floors. If you are in a single story building, stay in the center away from windows, doors, and exterior walls. You can also take shelter in a basement. If you are a first responder or radiation worker, you can use personal protective equipment (PPE) to minimize your exposure.
If radioactive material gets on skin, clothing, or hair, it’s important to get it off as quickly as possible. For information on decontaminating yourself, click here Anybody who works with radiation should work with their safety officers and radiation safety professionals. They should work together to determine PPE and instrumentation needed to stay safe. Control & PreventionThis section provides information on controlling ionizing radiation hazards and preventing dose. This section does not address the range of non-radiological safety and health hazards for workers in occupational settings with ionizing radiation hazards. For example, these non-radiological safety and health hazards may include electrical hazards from associated electrical equipment and extension cords, shift work and long work hours, worker ingress (entry) into and egress (exit) from shielded enclosures (e.g., at fixed industrial radiography facilities), and laser hazards if lasers are incorporated into radiation-emitting equipment (e.g., lasers are sometimes used to align an external beam with the target).
Radiation Protection Program Developing and implementing a radiation protection program is a best practice for protecting workers from ionizing radiation. A radiation protection program is usually managed by a qualified expert (e.g., health physicist), who is often called a radiation safety officer (RSO). Another best practice is designating a radiation safety committee, which includes the RSO, a management representative, and workers who work with radiation-producing equipment, radiation sources, or radioactive materials (or who are otherwise at risk of exposure on the job). A radiation protection program should include, at a minimum: Equipment Registration/Licensing Federal and state regulatory agencies require some types of radiation-producing equipment or radiation sources to be registered or licensed by manufacturers and/or users. Registration or licensing requirements apply to many specific radiation sources and occupational settings (e.g., medicine, manufacturing and construction). Equipment registration or licensing helps ensure that radiation sources emitting ionizing radiation do not pose radiation hazards for workers (and the public). Some radiation sources, such as most X-ray equipment and some accelerators, must be registered with a state agency (e.g., state radiation control agency, state health department) or local agency (e.g., health department) and different registration requirements may apply, depending on the agency. Registrants may be required to perform equipment tests or allow state or local inspectors to perform equipment tests. In some states, equipment registration requirements may include regular inspections, shielding, or signage.
NRC (U.S. Nuclear Regulatory Commission) regulations for radiation protection programs (10 CFR 20.1101) or state regulations for such programs apply to some specific radiation sources and occupational settings. OSHA's Ionizing Radiation standards apply where they are not pre-empted, and, in those cases, require certain elements of a radiation protection program. ALARAA key concept underlying radiation protection programs is keeping each worker's occupational radiation dose As Low As Reasonably Achievable (ALARA). An ALARA program usually involves maintaining radiation doses to workers as far below the federal and state regulatory occupational dose limits as is reasonably achievable taking into consideration the state of technology, economics, and social factors. ALARA in the workplace minimizes radiation doses and releases of radioactive materials using all reasonable methods available. ALARA procedures are typically developed for working with specific radiation sources, for example, diagnostic radiography (e.g., medical X-rays), fluoroscopy in medicine, or industrial radiography. Time, Distance, and Shielding When it comes to ionizing radiation, remember time, distance, and shielding:
Time, Distance, and Shielding for Radiation Protection Source: NRC Engineering Controls Employers should use engineering controls to maintain occupational radiation doses (and doses to the public) ALARA is applied after determining that radiation dose will not exceed applicable regulatory dose limits. To the greatest extent possible, administrative controls should not be used as substitutes for engineering controls. Engineering controls, in some cases, may be incorporated into facility design. Some examples of engineering controls are discussed below, including shielding and interlock systems. In addition, radioactive material containment is sometimes incorporated into shielding, such as in gamma cameras used for nuclear medicine or industrial radiography devices containing a radioactive source. Shielding The need for shielding depends on the type and activity of the radiation source. Uses in adjacent areas, including the areas above and below the room or facility, should also be considered. For shielding of rooms containing medical X-ray equipment or rooms with other medical X-ray imaging devices, the National Council on Radiation Protection and Measurements (NCRP) recommends that the shielding design goal be 500 mrad (5 mGy) in a year to any person in controlled (restricted) areas. For uncontrolled (unrestricted) areas, NCRP recommends that the shielding design goal be a maximum of 100 mrad (1 mGy) to any person in a year (~0.02 mGy per week).1 Shielding design requires a qualified expert (e.g., health physicist). Before using any new or remodeled rooms or facilities or any new or relocated X-ray equipment, a qualified expert should conduct an area survey and evaluate shielding to verify radiation protection behind shielding materials. Before performing any room modifications or if any changes occur to a facility that may change radiation exposure levels (e.g., new equipment, increased workload, altered use of adjacent spaces), a qualified expert should review the shielding design. In general, the floors, walls, ceilings, and doors should be built with materials that provide shielding for the desired radiation protection. Lead shielding may be installed, if appropriate, including leaded glass, sheet lead (e.g., built into walls), pre-fabricated lead-lined drywall or lead-lined plywood, pre-fabricated lead-lined doors and door frames, lead plates, and lead bricks. Sometimes it may be sufficient to construct a wall of a suitable thickness of normal building materials (e.g., dense concrete). The shielding design may include a control booth or load/lead-equivalent drapes provided for protection of workers operating equipment or devices that emit ionizing radiation. More information on shielding criteria is provided in the following NCRP reports:
Portable or temporary shielding materials (e.g., thick steel, lead, or high-density concrete blocks) can sometimes be fabricated in the area of the inspection when conducting portable industrial radiography (e.g., using industrial radiography cameras to inspect pipe welding or concrete slabs). Where such portable or temporary shielding is not practical or adequate to protect workers (and the public), employers should ensure that operating procedures maximize distance from the portable industrial radiography equipment while it is operating. When working with high-energy beta particles, avoid shielding with high atomic number (Z>13) materials as this can result in production of X-rays (Bremsstrahlung radiation), which are more penetrating than the original beta radiation. Beta particles should be shielded using an appropriate thickness of low atomic number (Z<14) materials such as aluminum or plastics (e.g., Plexiglas®). Interlock Systems A radiation safety interlock system is a device that automatically shuts off or reduces the radiation emission rate from radiation-producing equipment (gamma or X-ray equipment or accelerator). The purpose of a radiation safety interlock system is to prevent worker exposure and injury from high radiation levels. Typically, interlock systems are required by state or federal (e.g., NRC, FDA (U.S. Food and Drug Administration)) regulations for equipment registration/licensing and performance/safety standards. In most applications, interlock systems to stop X-ray or particle beam production can be activated by the opening of a worker access point (e.g., door) into a controlled (restricted) area. Interlock safety systems may also include door pressure sensors or motion detectors. For applications involving high-energy radiation sources, a system with interlock keys can control access or prevent entry into a radiation treatment room or during accelerator operations. Because removal of interlock keys will stop X-ray or particle beam production, such interlock systems rely on constant monitoring of all interlock keys and appropriate worker training for controlled access to high radiation areas. In addition to worker safety, patient safety is a concern for interlock systems for medical X-ray equipment or accelerators. NCRP recommends that interlock systems that stop X-ray or particle beam production should not be placed on doors to any diagnostic or interventional X-ray room to prevent inadvertent patient injury or the need to repeat exposures to patients.1 As an alternative, appropriate access control measures could be implemented at such facilities for both worker and patient radiation safety. When used, interlock systems should be inspected regularly by a qualified expert. Administrative Controls Administrative controls generally supplement engineering controls. Examples of administrative controls include signage, warning systems, and written operating procedures to prevent, reduce, or eliminate radiation exposure. Operating procedures typically include both normal operating procedures and emergency procedures (i.e., those for spills, leaks, and emergency evacuation). OSHA's Ionizing Radiation standards specify certain types of administrative controls in worksites where they apply. The bullets below provide more details about specific posting provisions for rooms in workplaces covered by the Ionizing Radiation standard for general industry (29 CFR 1910.1096)—including on vessels and on shore in shipyard employment, marine terminals, and longshoring. Employers may also be required to comply with provisions of other OSHA standards, including the Ionizing Radiation standards for construction (29 CFR 1926.53), which incorporates by reference the same types of controls described in the general industry standard, and shipyard employment (29 CFR 1915.57), which applies the NRC's Standards for Protection Against Radiation (10 CFR part 20) to activities involving the use of and exposure to sources of ionizing radiation on conventionally and nuclear-powered vessels.
Warning Systems Warning systems can be integrated into the design of radiation-producing equipment or devices and can also be used with radioactive materials. Such warning systems will set off an audible (easy to hear) alarm (e.g., to warn workers that a radiation hazard exists) or a visible (lighted) warning signal whenever ionizing radiation is being emitted. As an example, industrial radiography equipment located in a fixed facility or room (e.g., industrial radiography room for conducting materials testing for quality control at a manufacturing facility) may include visible warning signals with colored or flashing lights or audible alarms with a distinct sound, which are located inside and outside the shielded enclosure for conducting industrial radiography. In this example, the visible alarm would activate when the radiation source is exposed or when X-rays or gamma rays are generated during industrial radiography operations. The audible alarm would sound if the door is opened to the shielded enclosure for the industrial radiography equipment. Other facilities, such as gamma irradiation facilities, also use warning systems. Warning systems should be checked regularly for proper function. Warning systems should be checked regularly for proper function. Personal Protective Equipment Personal Protective Equipment (PPE) is used to prevent workers from becoming contaminated with radioactive material. It can be used to prevent skin contamination with particulate radiation (alpha and beta particles) and prevent inhalation of radioactive materials. PPE will not protect workers from direct, external radiation exposure (e.g., standing in an X-ray field), unless the PPE contains shielding material. For example, a leaded apron will reduce X-ray doses to covered areas. Consult a qualified expert (e.g., a health physicist) when choosing PPE and developing a PPE policy for a workplace. Consistent with the hierarchy of controls, PPE should only be used when appropriate engineering controls or administrative controls are infeasible. Alpha Radiation Alpha particles have very low penetrating power, travel only a few centimeters in air, and will not penetrate the dead outer layer of skin. Shielding is generally not required for alpha particles because external exposure to alpha particles delivers no radiation dose. Where particulates contaminated with alpha particles are present, engineering controls (e.g. glove boxes) or respiratory protection may be required to prevent an internal exposure and dose. More information about respirators is provided below. When working with liquid sources that contain alpha particles, additional PPE, such as gloves, a lab coat, and safety glasses, may be required to prevent contamination or contact with the eyes. Beta Radiation High-energy beta particles can travel several meters in air and can penetrate several millimeters into the skin. For high-energy beta particles, first select adequate shielding with an appropriate thickness of low atomic number (Z<14) materials, such as specialized plastics (e.g., Plexiglas®) or aluminum. Using safety goggles as PPE can help protect workers' eyes against beta particles as well as provide splash protection for the eyes (preventing potential internal exposure). Gloves and a lab coat may be used to prevent skin contamination. X-ray and Gamma Radiation Gamma rays and X-rays can travel kilometers in air and can penetrate deep into the human body or pass through it entirely. Proper shielding should be in place to prevent or reduce radiation dose rates. Some PPE for worker protection from gamma and X-rays incorporates lead or other dense, high atomic number (high Z) materials. As described under the ALARA section, it is also important to consider the inverse square law for gamma and X-rays when choosing appropriate PPE. Examples of commonly used PPE for radiation protection from X-rays and gamma rays include:
Respirators Although respirators are typically the last choice for controlling internal exposure to airborne radionuclides, reducing internal radiation dose, employers should ensure that workers use properly selected respirators and wear those respirators when required. Respirators should only be used by workers qualified to wear them. See 29 CFR 1910.134 for requirements for using respiratory protection. Radiation Measurement and Sampling OSHA's Ionizing Radiation standards often require employers to monitor radiation exposure, including by measuring radiation levels in the work environment and tracking the radiation doses that workers receive. Several types of area monitoring, personal dosimetry, and sample analysis equipment and techniques may be involved in effective radiation measurement efforts. This section discusses Survey Instruments Radiation survey instruments can be used to evaluate exposure rates, dose rates, and the quantities (activity) of radioactive materials and contamination. The survey instrument must be appropriate for the type and energy of the radiation being measured. A qualified expert should provide oversight for selecting appropriate area survey instruments, using survey instruments properly when conducting area surveys or monitoring, interpreting survey results, and ensuring accurate calibration and maintenance. Under OSHA's Ionizing Radiation standards, employer responsibilities typically include surveying radiation hazards to comply with the standard (29 CFR 1910.1096(d)(1), 29 CFR 1926.53). This is true for most operations in general industry, construction, shipyards, marine terminals, and longshoring.
Dosimetry OSHA’s Ionizing Radiation standard requires employers to conduct dose monitoring when a worker who enters a restricted area receives or is likely to receive a dose in any calendar quarter in excess of 25% of the applicable occupational limit (or 5% for workers under age 18) and for each worker who enters a high radiation area (1910.1096(d)(2) and 1910.1096(d)(3), 29 CFR 1926.53). See the Standards page for information about OSHA’s Ionizing Radiation Standard. An employer’s radiation protection program may require more stringent personal exposure monitoring for workers who enter restricted or high radiation areas, or use equipment or conduct job tasks that produce high levels of radiation (e.g., fluoroscopically-guided heart (cardiac) catheterizations, other fluoroscopically-guided procedures, radiography, industrial radiography).
Radiological Sampling and Analysis Sampling and analytical methods and equipment allow radiation safety professionals to identify areas with radioactivity, including where radioactive materials have contaminated environmental surfaces and other objects as well as environments that have radioactive materials in the air. Radiation safety professionals also use such methods and equipment to quantify how much radiation is present in order to determine how best to protect workers. This section discusses several sampling methods.
Sample Analysis Equipment Radioactive samples can be evaluated using a variety of equipment types depending on the type of sample (e.g. air, water, soil, surface wipe) and the types of radiations emitted by the sample. The following are examples of some of the types of equipment used to evaluate radioactive samples.
Whole Body Counting A whole body counter is a detector, or series of detectors, used to measure the amount of radioactivity in the human body. These instruments rely on the measurement of gamma and x-rays emitted from the radioactive material deposited in the body. Gamma spectroscopy systems are usually used in whole body counting systems. Counting is often used in occupational settings to conduct measurements of radiological workers at the beginning of employment, periodically during employment, after known or suspected intakes, and at the termination of employment in order to determine occupational radiation doses. Bioassay Sampling Bioassay sampling is sometime used in occupational settings to determine the uptake of radioactive material for radiological workers. Samples are typically collect at the beginning of employment, periodically during employment, after known or suspected intakes, and at the termination of employment in order to determine occupational radiation doses. Bioassay samples most commonly include urine, feces, and blood. Worker Training One of the most important functions of a radiation protection program is training radiation workers on safe work practices. Employers should provide workers with information and training to ensure that those who are potentially exposed to ionizing radiation hazards understand how to safely use all radiation-producing equipment or radiation sources in the workplace. Providing workers with information and training is closely tied to awareness of regulations because federal and state regulations often include performance and safety standards for specific radiation-producing equipment or radiation sources. Employers should ensure that workers understand mandatory performance and safety standards that help protect workers from exposure to ionizing radiation. Some state agencies may regulate the operation of electronically-produced radiation equipment through recommendations and requirements for personnel qualifications (e.g., licensing or certification), quality assurance and quality control programs, and facility accreditation. Those mandatory personnel qualifications are another important part of protecting workers from exposure to ionizing radiation. For more information, read the American National Standards Institute (ANSI)/Health Physics Society (HPS) N13.36, Ionizing Radiation Safety Training for Workers. Hazard-Specific Control Resources In addition to the general methods of control described above, there are several resources included on the Additional Resources page that provide information on controlling specific radiation hazards, including medical sources (i.e., diagnostic X-rays and fluoroscopically-guided interventional procedures), dental and veterinary X-rays, particle accelerators, industrial radiography, security screening, and radon. What is the common material used for shielding during radiographic procedures?Lead is one of the most used and most effective shielding materials. It is a highly dense material with a high atomic number and a high number of electrons which make it ideal for shielding in most medical radiation environments.
What is the most common type of shielding used for patients?Protective Shielding
Shielding is used to protect radiosensitive areas of the body by adequately attenuation the radiation with a 0.5 mm lead protection. The most commonly used type of shielding is gonadal shielding.
What is the most common material used for shielding of patients and radiographers?Lead shielding, often used in a variety of applications including diagnostic imaging, radiation therapy, nuclear and industrial shielding.
What are the 3 types of shielding?3 Different Types of Radiation Shielding Materials. Traditional Lead Shielding.. Lead Composite Shielding.. Lead-Free Shielding.. Which Material Is The Best To Use?. |
Which is the most common and important area for shielding during a radiographic procedure
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