Lead Garments (Aprons, Gloves, etc.)
Where should a half apron be placed for an erect chest x ray and why (i.e., at the back of the patient for protection from the primary beam or in front of the patient to protect from backscatter from adjacent structures)?
It is common practice to place a half apron behind the patient during an erect chest radiograph to reduce potential dose from tube leakage and room scatter. For all practical purposes, the dose from these sources is not measurable in modern chest x-ray rooms, thus the apron has minimal value. Protection from the primary beam is not necessary since it is collimated to the size of the film or image intensifier. Most of the backscatter is from the patient, thus any dose to the gonads and other tissues outside the beam results from internal scatter. Consequently, the half apron has minimal effect on patient dose, but it does reassure patients that precautions are taken to protect them from unnecessary radiation exposure.
My child had x rays taken and was given a lead shield to cover his gonads. Was this amount of shielding adequate enough to protect him from the radiation? Also, why is the gonad shield so small compared with the large lead apron that is always placed over me during dental x rays?
The use of a lead shield for gonadal protection is very typical in most x-ray departments and is typically mandated by regulations administered by the state you are in. Usually the only shielding for the patient that is required is gonadal shielding if the gonads are in, or near, the primary x-ray beam. In many cases, the x-ray field is not necessarily near his gonads, but the gonadal shield is added as a precaution for a pediatric patient.
The amount of radiation that scatters within the body is very small away from the area x rayed and would add a negligible amount of exposure to an amount that was very small to start with.
It turns out that many national recommendations regarding shielding the patient are now indicating that the use of a lead apron over the patient does little in the way of significant radiation dose reduction (except for the case of shielding the gonads or some other specific organ in the direct beam). Dental guides are very specific that if all routine precautions are used, the lead apron on the patient is unnecessary. The reason we still recommend their use is for "peace-of-mind" reasons for the patients or their family members.I think it just turns out that the hospital or physician's office that does x rays usually has a variety of apron sizes and they choose the one most appropriate. The dental offices, on the other hand, typically have one size and use it for everyone.
Why do people of reproductive age have to wear a lead apron when having an x ray?
Lead aprons reduce the radiation dose to the reproductive organs from a variety of diagnostic x-ray procedures. Radiation has a potential of causing mutations in the germ cells that may be passed on to future generations. However, studies of the Japanese survivors of the atomic bombings and their offspring suggest that the doses necessary to produce genetic damage is quite high-much higher than typical diagnostic x-ray procedures. Lead aprons serve a precautionary purpose to reduce dose.
If the risk of thyroid cancer is so low, particularly in relation to x-ray medical staff, why are thyroid shields used?
Even though risk is low, it is prudent to reduce radiation dose when it is feasible and practicable. Using lead shields to block the thyroid is an easy dose-reduction strategy and costs (purchase of lead apron or shield) are relatively inexpensive over their usable lifetime.
Where is the lead located in the protective clothing worn by radiographers? Is it in an inner layer of the material? Or is it mixed throughout the material, and therefore comes into contact with bare skin when worn?
Protective clothing worn by radiographers contains lead and often other metals (e.g., tin, tungsten, antimony, barium) to shield the wearer from radiation. These metals are homogeneously mixed with synthetic rubber or polyvinyl chloride (PVC). Between two and five thin sheets of metal-impregnated rubber/PVC are placed between sheets of nylon fabric coated with urethane on the side against the lead-impregnated rubber/vinyl. The materials are cut into a pattern and sewn together to form the protective garment. The manufacturers of these garments vary the number of sheets, the percentage of metal, the grade of rubber or PVC, and the mixture of metals to affect flexibility, durability, radiation absorption efficiency, and weight.
I am looking for a manufacturer of lead rubber cloth. Could you recommend some?
There are a number of manufacturers/suppliers of lead aprons. A basic Internet search using the key words "protective lead apron" gives about 10,000 "hits" including the following:
When you discuss the radiation received from x rays, are lead aprons taken into consideration? Does a lead apron decrease the radiation received as a patient?
Typically, we do not take a lead apron into consideration for patients undergoing medical procedures involving radiation because the area of interest will not be covered. Lead aprons are taken into consideration if the person is occupationally exposed (we make an assumption that if a person is in an x-ray room during a procedure, but is not the patient, a lead apron is worn) or if the question specifically asks about the use of aprons.
If an apron were in the primary x-ray beam between you and the x-ray machine, the apron can stop at least 90 percent of radiation from entering your body. It is not practical, however, to put an apron over a body part of interest to the physician.
Lead aprons have to be inspected visually every six months. Where does this requirement come from?
Lead aprons are used in medical facilities to protect workers and patients from unnecessary radiation exposure from diagnostic radiology procedures. Due to standards set forth by The Joint Commission, health care organizations must perform inspections on medical equipment, including lead aprons. State departments of health may also have a regulation stipulating that lead aprons be checked.
The Joint Commission standard does not dictate inspection frequency, method, or rejection criteria, although state regulations might. This allows facilities to develop their own policies and procedures to evaluate their lead aprons. Typically, a facility will perform an inspection of each apron on an annual basis. Some facilities choose to survey their aprons on a more frequent basis, such as every six months. This may be recommended if aprons are heavily used and/or are not always properly stored after use (folded or piled up instead of placed on a hanger).
There are two recent articles that address lead aprons, referenced below. One addresses implementing an inspection program and includes techniques for testing aprons, and the other proposes a rejection criteria based on effective dose equivalent, that is, the whole-body dose based on dose to various critical organs.
The following questions have come up for someone who is occupationally exposed to radiation but unable to wear a lead apron supported at the shoulder due to a medical restriction.
Lead aprons are very effective at absorbing diagnostic x rays to the parts of the body shielded by the apron. Their effectiveness is energy dependent but averages around 90-95 percent. Leaded aprons are worn as good radiation safety practice and in keeping with the ALARA (as low as reasonably achievable) concept. Whether or not a lead apron is worn, the allowable exposure to the body is governed by the occupational exposure limits. Leaded aprons are not the only means of shielding the body.
There are mobile shields that provide just as much protection from exposure as the leaded aprons. A lead apron does not have to be worn, so long as it is between the user and the radiation source. It would work just as well if it were suspended from the ceiling or draped over a support so the radiologist could stand behind it. Either of these methods would provide the protection available from the apron while sparing the user's shoulder. Wearing just a leaded skirt would provide only a fraction of the protection provided by a full apron. You may want to check your state's regulations (if in the United States) to see what requirements they have for wearing lead aprons.
What are the facts about titanium aprons compared with lead aprons?
Titanium is used in aprons as the shielding material instead of lead. Other material used includes bismuth and barium. In evaluating the shielding properties of materials, their mass and linear attenuation coefficient needs to be considered. Mass attenuation coefficients for various elements can be found through the National Institute of Standards and Technology (NIST) Physical Reference Data website.
First, consider the amount of material needed to provide the same amount of protection as 0.5 mm of lead, which is protection provided by many leaded aprons. At 60 keV (6.0 × 10-2 MeV), the mass attenuation coefficient, µ/ρ, of lead is 5.021 cm2 g-1. Multiplying by the thickness of 0.05 cm and the density of lead, 11.35 g cm-3, gives 2.85. The negative value of this coefficient is the exponent in the basic attenuation equation, I' = Ie-2.85, where I is the intensity of the unshielded x-ray field and I' is the intensity of the shielded x-ray field.
The amount of titanium needed to provide the same amount of shielding as 0.5 mm of lead can be found by dividing the exponent 2.85 by the density of titanium, 4.54 g cm-3, and dividing by the mass attenuation coefficient of titanium of 60 keV, 0.7661 cm2 g-1. The result is 0.82 cm of titanium. Thus, the thickness of titanium needed to provide the equivalent shielding of lead is 16.4 times that of lead. This value may be misleading if one considers the weight of the apron. The ratio of the weight of the titanium apron to a lead apron of the same size can be computed as the ratio of the density times the equivalent shielding thickness, i.e., (density of titanium) × 0.82 cm / (density of lead) × 0.05 cm. A titanium apron would weigh about 6.6 times a lead apron.
The real advantage in using titanium is that it is not a hazardous material such as lead. Thus, if you are looking for a reduction in hazardous waste, the titanium aprons may be a good option. Alternate nonhazardous shielding materials include bismuth, as its mass attenuation coefficient for 60 keV photons is greater than that for lead, and it is less dense than lead. The advantage of lead is and will remain that it is inexpensive.
My daughter needs several arm x rays. Should I ask for the rest of her body to be shielded when the arm x rays are being taken?
All responsible authorities and expert bodies recommend that medically indicated x-ray exposures be performed as needed, on the grounds that the benefit of the diagnostic information provided greatly overrides any potential risk. Further, there is no conclusive proof that medical exposures, as currently performed, harm anyone. Finally, the exposure required for an extremity x ray is extremely small. The x-ray beam is confined to the area being imaged. The exposure to the remainder of the body is too small to measure. Therefore, shielding of the subject's body produces no detectable difference in the amount of exposure received.
How long does a lead apron need to be? Does it need to cover the femurs? Does it need to be a wrap-around if I routinely have my back to the fluoroscopy table?
The stochastic or cancer risks from low-level, low-dose-rate radiation exposure are based on the doses to various radiosensitive critical organs. The major critical organs include the gonads, breast, active bone marrow, lungs, thyroid, bone surfaces, and, to a lesser degree, various other organs in the trunk of the body. Except for various regions of active bone marrow and the brain, which has a small associated risk from radiation exposure, nearly all the critical organs can be shielded by a lead apron that has a length to about mid-femur. The bone marrow not shielded by a standard leaded apron is in the skull, cervical vertebrae, and long bones of the arms and lower long bones of the legs.
With regard to types of leaded aprons, I strongly recommend a wrap-around or coat-type apron to reduce exposures to the bone marrow in the vertebrae and critical organs in the trunk when your back is toward the fluoroscopy unit. A very good option is a combination vest and skirt apron, which wraps around the body and distributes the weight across the shoulders and hips.
If the chances of damage to reproductive organs from x rays is so small, why do patients have to wear protective aprons?
Leaded aprons are used for diagnostic x-ray procedures to protect those portions of the body that are not involved in the image. The risk to the patient from diagnostic doses is very small and may even be zero. However, the apron is used in an application of the ALARA concept: the dose should be kept As Low As Reasonably Achievable. The apron is inexpensive and carries no discomfort or risk. Although it may be unnecessary for many very low-dose procedures such as chest or dental x rays, it is a prudent practice.
What is the criteria for gonadal shielding for radiation protection purposes?
From your question, I do not know if you are referring to protection for patients during radiological exams or for occupational workers. I will give you answers for both situations, but will not discuss the protection of the embryo or fetus.
For patients, the gonads may or may not be in the primary x-ray field. If they are not in the primary field, the radiation exposure drops off rapidly as dose will be due to x-ray tube leakage and scatter radiation only. In practice, the patient may be provided with a leaded apron anyway, because the staff has been trained to do that or to provide reassurance to the patient.
For the situation where the gonads are in the primary radiation field, shielding should be employed as long as the areas of interest are not blocked by the shielding. An example might be to image the pelvis to evaluate the heads of the femur bones. For males, the testes are easily shielded by special shields that are in contact with the body. Alternately, shadow shields can be used. These are typically triangular pieces of lead that are suspended by flexible arms (like those for desk lamps) from the x-ray tube housing. Since the collimator light field is aligned to the x-ray field, the shadow cast by the suspended piece of lead will show what area is being shielded from the x rays produced. For females, the gonads are not visible or generally localized in the abdomen. As such, shielding is seldom employed for females, but the x-ray field collimators may be used to shield the center of the abdomen.
For occupational workers, specific gonad shields are not employed. The gonads are considered one of a number of critical organs which have a certain enhanced risk associated with ionizing radiation exposure. Unlike the gonads, where the risk is associated with genetic mutation, the risk to other critical organs is associated with carcinogenesis. Efforts are usually made to shield as many of the critical organs as possible rather than just one. Generally structural shielding is used to shield workers. Leaded aprons are commonly used in radiology procedures.
How do lead rubber aprons protect the person underneath? Does this apply to all forms of lead protection, that is, thyroid protection?
Protective lead aprons and thyroid shields contain lead to shield the wearer from radiation. Lead aprons and thyroid shields are placed between the person being protected and the x-ray source (for example, radiographic or fluoroscopic x-ray units, CT scanners, DEXA scanners). X rays are more likely to interact with large atoms (atoms with lots of protons and electrons) than they are with smaller atoms, and lead, tungsten, and even gold are examples of large atoms that can be used. Each time an x ray interacts, it uses some or all of its energy to knock electrons in the atoms around. When all of the energy is used up interacting with atoms, the x ray ceases to exist. If the x ray gives up its energy to lead atoms in the lead apron, then it is not available to knock electrons around in atoms in your body. So the lead apron protects people by absorbing the x-ray energy before the x ray can get to the body and start knocking electrons around.
Although it depends on the x-ray source and the amount of lead in the apron, typically 90-95 percent of the x rays striking a lead apron will be absorbed in the lead apron, leaving less than 10 percent to interact in the body.
Are radiation protective garments, or other protective items made from lead, being restricted because of lead's toxicity?
The hazards of lead are well documented, and there are many programs to control or eliminate lead exposure in the United States, for example, the one developed by the National Safety Council's Environmental Health Center. However, I am not aware of any specific program to restrict the use of lead in radiation protective garments. The risk would be when the rubber-like material with which the lead is mixed dries out and is inhaled or ingested. These are the same pathways associated with handling or working with lead bricks or sheets, not wearing dust masks and gloves, or washing your hands after handling bare lead. I cannot imagine that inhaling or swallowing particles from leaded aprons would present a significant source of lead poisoning.
Is there any substantiation to the claim that radiation-resistant gloves do reduce exposure to the hands?
Exposures to the hands, which is really exposure of the skin of the hands or extremities, has always been a concern in radiology. For many years, only heavy, leaded gloves were available and worn during certain fluoroscopic procedures. I could find only one report on skin exposures in radiology which reviewed 30 different interventional radiology cases (Felmlee et al. 1991). It reported that the average hand dose was 150 mrad and ranged from 0 to 550 mrad. Of course, the number of procedures performed in a year must also be considered in evaluating the risk to your staff. For regulatory purposes, the limit to the skin or extremities is 50,000 mrad per year as opposed to 5,000 mrem per year for the critical organs of the body. This risk is based on protracted doses to the skin totaling 300,000 to 400,000 mrad, which may lead to dermal atrophy and damage to the vascular tissue rather than cancer.
To judge the radiation shielding effectiveness of different products, it is useful to compare equivalent shielding values. This is important as many new types of gloves and pads are being made using bismuth, tungsten, or titanium rather than lead. For example, some lead vinyl gloves may have a shielding value of 0.5 mm of lead. Conversely, another product that uses bismuth may have the equivalent shielding value of 0.04 mm of lead. Besides attenuation properties, considerations should be given to the flexibility of the gloves and sensitivity to touch. In addition, the newer types have the advantage of not having to be disposed as hazardous waste like lead has to be. It is important to remember that any radiation-resistant gloves are not designed for use in the primary x-ray beam. They are intended to reduce the scattered radiation to which the surgeon's hands will be exposed. As such, they should be considered a piece of safety equipment to help reduce radiation exposures and risks.
Felmlee JP, McGough PF, Morin RL, Classic KL. Hand dose measurements in interventional radiology. Health Phys 60(2):265-267; 1991.
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