Resource
Discontinuation of gonadal and fetal lead shields
Medical Imaging Departments in Vancouver Coastal Health, Fraser Health, Providence Health, and the Provincial Services Health Authority located in the Lower Mainland of British Columbia, Canada, are discontinuing the routine use of lead shields.
Medical scientific experts including medical physicists, radiologists and radiation technologists, have recently concluded that lead shields placed on the patient during diagnostic medical imaging, a common practice for more than 70 years, are no longer necessary. As of July 13, 2022, Medical Imaging staff will no longer routinely provide gonadal and fetal lead shields to patients.
Why change practice?
Use of lead shields to protect the gonads (male and female reproductive organs) and unborn fetus's from radiation exposure was first introduced in the 1950's when the scientific understanding between radiation exposure and health effects was limited. This practice was implemented due to lack of scientific knowledge regarding the long-term effects of ionizing radiation to the reproductive organs, fetus, and future progeny.
Over the last 70 years x-ray technology has improved. Today, modern x-ray systems are highly efficient compared to plain film systems used in the past using less radiation to form the image or picture. In addition, modern x-ray systems have embedded technology that can tailor the radiation required to the patient size. Finally, new scientific evidence has shown suggest radiation exposure from routine diagnostic x-ray exams poses no adverse long-term effect to the reproductive organs, cells, a fetus or progeny.
In the past 70 years, the following has changed:
- Scientific evidence has shown negligible, if any, link between low levels of x-ray radiation exposure and biological effects to the fetus or future progeny (offspring, or heritable effects).
- Technological advancements have led to lower radiation requirements per radiograph (the x-ray picture).
- Modern x-ray systems have a feature called "Automatic Exposure Control” or "AEC." This AEC technology ensures the radiation reaching the image detector to form the x-ray picture is correct using the lowest dose possible to create the best image.
- Lead shields, in a very small number of cases, may increase radiation exposure if the lead shield is not placed correctly or moves into the radiation field after placement. This is because the AEC technology terminates radiation exposure when the detector has received sufficient radiation to form a diagnostic image. Incorrect placement of the lead shield may lead to a malfunction with AEC technology, potentially increasing patient dose.
- Patients can be confident that hospitals and imaging centers follow the ALARA principle (As Low As Reasonably Achievable). This means medical radiation technologists (MRTs) and physicians, use the lowest amount of radiation necessary to produce diagnostic quality images. Increasing numbers of hospitals across North America have stopped using lead shields. However, imaging centers in Canada may still use lead shields based on internal guidelines. Many private centers in the Metro Vancouver will adjust their practice after Medical Imaging in the public Health Authorities has changed practice. If you have questions about policies where you have your imaging done, please ask your physician.
Find more information on the role of patient gonadal and fetal shielding in Radiology.
Frequently Asked Questions
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Where did this change originate?
The American Association of Medical Physicists (AAPM) published a position statement in 2019 recommending the discontinuation of routine gonadal and fetal use. As this has been common practice for over 70 years, the AAPM formed the AAPM CARES Committee to create education material for patients and staff.
Read the AAPM frequently asked questions (PDF)
The position statement from the AAPM has been, endorsed by the following national and international organizations:
Canada
- Canadian Association of Radiologists (CAR)
- Canadian Organization of Medical Physicists (COMP)
- Canadian Association of Medical Radiation Technologists (CAMRT)
International
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Where else is the discontinuation happening?
Like many jurisdictions in both Canada and the United States, changing a common practice may also require regulatory and accreditation changes. In the fall of 2021, the Diagnostic Accreditation Program of BC (DAP), part of The College of Physicians and Surgeons of British Columbia, updated standards to reflect the AAPM Statement. This has enabled hospitals and private clinics in BC to change practice.
In addition to changing regulations and accreditation. The Health Authorities in Lower Mainland of BC will be required to educate health-care professionals on this change. As such, each Health Authority and private clinic will have their own timeline for this change in practice; however, we anticipate our public health authority partners in BC will have implemented this change before the end of 2022.
Diagnostic Accreditation Program of BC – Accreditation Standard Changes
DAP Standards - Prior language
RS 2.1.3
Shielding is used, where appropriate, to limit the exposure of body tissues and when clinical objectives will not be compromised.
Intent: It is particularly important to protect sensitive body tissues and children. Appropriate use of specific area gonad shielding is advised when: the gonads lie within, or are in close proximity to, the X-ray beam; the patient is of reproductive age; and clinical objectives will not be compromised.
Gonad shields are of sufficient size and shape to exclude the gonads completely from primary beam irradiation. Note: For CT breast shields, using some vendor scanners may increase patient dose. It is recommended to consult with manufacturers on the use of breast shielding.RS 2.2.4
When radiological examinations of the pelvic area or abdomen are
required full use is made of gonadal shielding and other protective shielding if the clinical objectives of the examination will not be compromisedDAP Standards - New standard (January 2022)
RS 2.1.3
Lead shielding is not routinely provided.
Guidance: If lead shielding is requested, it may be used when clinical objectives will not be compromised.RS 2.2.4
Standard deleted. -
I was given a shield in the past, and I would feel safer if I were provided one now
If you have had imaging exams with a lead shield, you may be fearful of having an exam without one. Pregnant mothers, parents, or guardians of children being imaged may be especially anxious about this change. This page also provides links to educational resources for patients, parents or guardians to review. There are many sources of misinformation online making it difficult to find accurate information.
However, if you still feel that a lead shield is required for your examination, the medical radiation technologist will provide one for you or your child.
Biological effects
In the 1950s, doctors began to shield reproductive glands and a pregnant woman's fetus during medical imaging. At the time, medical experts were unsure about the long-term effects of radiation exposure to an unborn fetus or to reproductive cells (testes and ovaries). They were also concerned damaged reproductive cells could be passed to future generations.
There is no evidence that shielding benefits patient health. In fact, shielding may do harm by covering a part of the body the radiologist needs to see. If this happens, the radiologist or radiographer may need to repeat the imaging exam leading to more radiation exposure to the patient.
Today, scientists and researchers also know more about how radiation affects the human body. Scientific evidence shows that routine diagnostic medical imaging exams do not expose the patient or fetus to harmful levels of radiation. After years of research, there is no evidence of damage to gonads or the fetus after routine medical imaging.
Technology improvement and background radiation
Medical imaging technology has made significant advances over the past 70 years. Hospitals and imaging centers now have better imaging devices that use much less radiation. These new devices can reduce radiation exposure to the reproductive glands during pelvic imaging by as much as 96%.
Since the 1980's the radiation required to form an image has dropped substantially.
Examples o reduction in radiation per exam
Lumbar spine exam; year and effective dose in mSv
1975, 5 (mSv)
2008, 1.5 (mSv)
2017, 1.3 (mSv)Mammograms; year and effective dose in mSv
1980, 3.36 (mSv)
1999, 0.72 (mSv)
2022, 0.24 (mSv)It is important to recognize that all Canadians are, exposed to background radiation. The average is 1.8 mSv in Canada, but varies depending on location. For example, the background radiation in Vancouver is 1.3 mSv/year, while it is 1.6 mSv/year in Toronto and 4.1 mSv/year in Winnipeg. As can be seen in the Table, radiation dose for 2 common exams is now below background radiation. More information on background radiation can be, found on the Canadian Nuclear Safety Commission (CNSC) website.
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I had an imaging exam before with a lead shield, what does this mean for my risk?
In very few circumstances, the use of a lead shield can increase radiation exposure. If this occurs, the increased radiation to create an image is still justified based clinical criteria that have met the accreditation requirements and standard of practice at the time of the exam. So exam benefits outweigh the radiation risk.
Resources
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FAQs
Patient gonadal and fetal shielding in diagnostic imaging
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American Association of Medical Physicists
CARE Committee
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Canadian Association of Radiologists (CAR)
Issues new position statement on gonadal and fetal shielding for x-ray
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Canadian Organization of Medical Physicists (COMP)
Position statement
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Canadian Association of Medical Radiation Technologists (CAMRT)
Position statement
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National Council on Radiation Protection & Measurement
NCRP recommendations for ending routine gonadal shielding during abdominal and pelvic radiography
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