X-Ray Safety: Radiation Exposure, Risks & Pregnancy Guidelines

Are X-Rays Safe? Understanding Radiation Exposure

X-rays are one of the most common medical procedures in the world, with hundreds of millions of imaging exams performed in the United States every year. Yet many patients still hesitate before an exam and ask the same question: are x-rays safe? The short answer is that for nearly all patients, the radiation dose from a routine diagnostic x-ray is very small, and the diagnostic benefit almost always outweighs the minimal risk. The longer answer—covered in detail in this guide—involves understanding how x-ray radiation exposure is measured, how doses compare to the natural radiation you receive every day, and which situations call for extra caution.

In this guide, we'll explain how x-rays work, show exactly how much radiation is in an x-ray using real-world dose comparisons, walk through the special considerations for children and for x-rays during pregnancy, and explain the safety principles—like ALARA and Image Gently—that radiology professionals follow to keep doses as low as reasonably achievable. We'll also cover the evolving science around lead aprons and shielding, how often is "too often" for x-rays, and the questions you should feel comfortable asking your technologist before any exam.

How X-Rays Work

X-rays are a form of electromagnetic radiation, just like visible light and radio waves, but with much higher energy. When an x-ray machine is activated, it sends a brief, controlled beam of x-ray photons through the part of your body being examined. Different tissues absorb x-rays differently: dense structures like bone absorb more of the beam and appear white on the image, while soft tissues absorb less and appear in shades of gray, and air-filled spaces like the lungs appear nearly black.

A detector on the other side of your body captures the photons that pass through, creating a two-dimensional image of your internal anatomy. The actual exposure lasts only a fraction of a second per image. Because x-ray photons carry enough energy to remove electrons from atoms, they are classified as ionizing radiation—and ionizing radiation, in large enough doses, can damage DNA in living cells. This is the basis of the safety question, and it's also why doses from medical imaging are carefully measured, regulated, and minimized.

It's important to understand two reassuring facts about diagnostic x-rays:

• The doses are tiny. Modern diagnostic x-rays use a small fraction of the radiation that older equipment required, and many common exams deliver less radiation than you'd receive from a few days of simply living on Earth.
• The exposure is not cumulative in your body. X-rays do not stay in your body after the exam, and you are not radioactive after an x-ray. Each exposure is a discrete event that ends the instant the machine switches off.

How Much Radiation Is in an X-Ray?

Radiation dose from medical imaging is measured in millisieverts (mSv), a unit that accounts for both the amount of radiation and its biological effect on the body. To make sense of these numbers, it helps to know one key benchmark: the average person in the United States receives about 3 mSv per year from natural background radiation—cosmic rays from space, radon gas in the air, and naturally occurring radioactive materials in soil, food, and water. People living at high altitudes, such as in Denver, receive somewhat more.

Here's how common x-ray exams compare, including the approximate amount of natural background radiation it would take to deliver the same dose:

A few takeaways from this table are worth highlighting. First, dental and extremity x-rays involve such small doses that they are comparable to the radiation you'd receive from a single coast-to-coast flight—or less. A dental bitewing at roughly 0.005 mSv is one of the lowest-dose exams in all of medicine. Second, a standard chest x-ray, at about 0.1 mSv, equals roughly ten days of ordinary background exposure. Third, there's a meaningful jump between plain x-rays and CT scans: a chest CT delivers around 7 mSv, roughly 70 times the dose of a chest x-ray, because it captures many cross-sectional images rather than one or two projections. That's exactly why doctors reserve CT for situations where the additional detail genuinely changes care.

Effective Dose vs. Background-Equivalent Time

You'll often see x-ray doses described in two ways, and understanding both makes radiation numbers far less intimidating:

• Effective dose (mSv): This is a calculated value that adjusts the raw radiation exposure for which organs were in the beam and how sensitive those organs are to radiation. It allows different exams to be compared on a common scale. An extremity x-ray has a very low effective dose partly because hands and feet contain few radiosensitive organs; a lumbar spine x-ray is higher because the beam passes through the abdomen and pelvis.
• Background-equivalent time: This translates the effective dose into the number of days, weeks, or months of natural background radiation that would deliver the same dose. It's the most intuitive way to grasp scale: telling a patient that a chest x-ray equals "about ten days of normal life" communicates more than "0.1 mSv" does.

Neither number is a precise measurement of your personal risk—individual doses vary with body size, equipment, and technique—but they are excellent tools for putting x-ray radiation exposure in honest perspective. At the doses used in routine x-rays, any increase in lifetime cancer risk is too small to measure directly and is estimated by extrapolating from much higher exposures. Regulatory and scientific bodies, including the National Council on Radiation Protection and Measurements (NCRP), nonetheless treat every dose as worth minimizing, which is why the safety principles described below exist.

X-Ray Safety for Children: The Image Gently Principle

Children deserve special consideration when it comes to medical imaging, for two reasons. First, children's tissues are more radiosensitive than adult tissues because their cells are dividing rapidly as they grow. Second, children have more years of life ahead of them, which means more time for any radiation-related effect to develop. Neither fact means children should avoid medically necessary x-rays—it means doses should be tailored to their smaller bodies.

The Image Gently campaign, launched in 2008 by the Alliance for Radiation Safety in Pediatric Imaging, transformed how children are imaged in the United States and worldwide. Its core principles include:

• Child-size the dose: Technique settings should be adjusted downward for a child's smaller size rather than using adult protocols.
• Image only when necessary: Providers should ask whether the exam will change management, and whether a non-radiation alternative such as ultrasound could answer the question.
• Scan only the indicated area: Limiting the x-ray beam (collimation) to the region of interest reduces dose to surrounding tissue.
• One scan is usually enough: Avoiding routine repeat or multi-phase imaging unless clinically required.

As a parent, you can support these principles by asking whether the facility uses pediatric protocols, keeping a simple record of your child's imaging history, and sharing prior images between providers so studies aren't repeated unnecessarily. Children's hospitals and facilities accredited by the American College of Radiology (ACR) routinely apply child-sized dose protocols.

X-Rays During Pregnancy: Current Guidelines

Few imaging topics cause more anxiety than x-rays during pregnancy, and the good news is more reassuring than most patients expect. The key concept is location: the concern with prenatal radiation exposure relates to dose received by the uterus and developing baby. X-rays of body parts away from the abdomen and pelvis—such as the teeth, chest, head, arms, hands, legs, and feet—deliver essentially negligible scattered dose to the fetus when performed properly.

What the Major Organizations Say

The American College of Radiology and the American College of Obstetricians and Gynecologists (ACOG) agree that no single diagnostic x-ray delivers a radiation dose high enough to threaten the well-being of a developing embryo or fetus. Harmful fetal effects (such as growth restriction or malformation) are associated with doses above roughly 50 mGy—far beyond what any routine x-ray produces. Even a maternal lumbar spine x-ray, one of the higher-dose plain films, delivers only a small fraction of that threshold to the fetus, and a dental or chest x-ray delivers close to none.

The Changing Role of Abdominal Shielding

For decades, draping a lead apron over a pregnant patient's abdomen was standard practice. That guidance has evolved. Research showed that shielding the abdomen during exams of other body parts provides little measurable dose reduction—most fetal dose from such exams comes from radiation scattering inside the mother's own body, which an external apron cannot block. Worse, a shield that drifts into the imaging field can obscure anatomy or confuse the machine's automatic exposure control, sometimes triggering a higher dose or a repeat exam. For these reasons, organizations including the American Association of Physicists in Medicine (AAPM) and the ACR now state that fetal shielding is generally unnecessary and may be discontinued as routine practice, although many facilities still offer it for patient comfort and reassurance.

Practical Guidelines for Pregnant Patients

• Always inform your provider and technologist if you are pregnant or think you might be—before any imaging exam, without exception. This allows the team to confirm the exam is appropriate, optimize the technique, and document the decision.
• X-rays away from the abdomen are generally acceptable when medically indicated. A pregnant patient with a suspected broken ankle, dental infection, or pneumonia should not avoid the imaging needed to treat her—untreated illness poses real risks to both mother and baby.
• Abdominal and pelvic imaging is weighed more carefully. Your provider may consider ultrasound or MRI (neither uses ionizing radiation) when those can answer the clinical question, or may proceed with x-ray or CT when the situation warrants it, such as suspected appendicitis or trauma.
• Don't delay urgent care. Both ACR and ACOG emphasize that necessary diagnostic imaging should not be withheld from a pregnant patient when it is needed to make a diagnosis.

The ALARA Principle: How Professionals Minimize Dose

Every radiology department in the country operates under the ALARA principle—As Low As Reasonably Achievable. ALARA holds that because we conservatively assume even small radiation doses carry some small risk, every exposure should be justified by a clinical benefit and optimized to use the minimum dose that produces a diagnostic-quality image. In practice, ALARA shapes nearly everything about your exam:

• Justification: An x-ray is only ordered when the result is expected to influence your diagnosis or treatment. Clinical decision rules (such as the Ottawa rules for ankle injuries) help providers skip imaging when it isn't needed.
• Optimization: Technologists select exposure settings matched to your body size and the body part being imaged, collimate the beam tightly to the area of interest, and position you carefully to get the image right the first time.
• Limitation: The number of views is limited to those clinically required, and repeat images are taken only when the originals are inadequate.
• Quality control: X-ray machines are inspected and calibrated regularly, and facilities accredited by the ACR meet defined dose and image-quality standards.

Lead Aprons, Thyroid Collars, and Evolving Shielding Guidance

If you've had x-rays over the years, you've probably worn a lead apron, and you may notice that practices now vary between facilities. That's because the science of patient shielding has changed significantly.

In 2019, the AAPM issued a position statement—endorsed by the ACR and other professional bodies—recommending that routine gonadal and fetal shielding be discontinued during x-ray imaging. The reasoning: modern equipment uses far lower doses than when shielding was introduced in the 1950s; shields frequently fail to cover the intended anatomy; most dose to organs outside the beam comes from internal scatter that aprons can't block; and misplaced shields can interfere with automatic exposure control or hide important anatomy, forcing repeat exams that increase total dose.

Thyroid collars remain a partial exception in dentistry. Because the thyroid gland is relatively radiosensitive and sits near the beam in some dental exams, a thyroid collar may still be used for certain intraoral x-rays—particularly in children—provided it doesn't interfere with the image. For panoramic dental x-rays, collars are typically not used because they can block the beam path. The American Dental Association updated its guidance in 2023 to state that lead aprons and thyroid collars are no longer routinely necessary for dental imaging given modern equipment and beam limitation, though state regulations vary and many practices continue offering them.

The bottom line for patients: if your facility no longer drapes you in lead, that reflects current evidence, not corner-cutting. And if wearing an apron makes you more comfortable, most facilities will gladly accommodate the request as long as it won't compromise the image.

How Often Is Too Often?

There is no official lifetime limit on the number of diagnostic x-rays a patient may receive, because each exam is judged on its own merits: if an x-ray is medically justified, the small dose is considered acceptable regardless of past imaging. That said, sensible practices keep cumulative exposure in check:

• Keep an imaging history. A simple list of your exams—what, where, and when—helps new providers avoid duplicating recent studies. Many health systems now track this automatically in your patient portal.
• Share prior images. Requesting that images be transferred between providers (usually free or low-cost on a CD or via electronic exchange) is the single easiest way to prevent unnecessary repeats.
• Ask about intervals for routine imaging. Dental check-up x-rays, for example, don't need to happen on a fixed schedule for everyone; the ADA recommends individualized intervals based on your cavity risk, which may mean bitewings every 6-18 months for higher-risk patients but every 2-3 years for healthy, low-risk adults.
• Question screening exams without symptoms. Routine x-rays without a clinical reason—such as annual chest x-rays in healthy non-smokers—are no longer recommended.

For perspective, a patient would need roughly 30 chest x-rays to equal one year of natural background radiation, and around 600 dental bitewings to reach the same total. Frequent medically necessary imaging is rarely a cause for alarm, but it is always fair to ask your provider, "Will this exam change my treatment?"

Digital vs. Film X-Rays: A Built-In Dose Reduction

One of the quiet success stories in radiation safety has been the industry-wide transition from film to digital detectors. Digital radiography sensors are far more sensitive than photographic film, which means they can produce a high-quality image with substantially less radiation—dose reductions of up to 50-80% are commonly cited for digital dental sensors compared with older film speeds. Digital systems also reduce dose indirectly:

• Fewer retakes: Images appear instantly and can be brightened or enhanced on screen, so slightly under- or over-exposed images often don't need to be repeated.
• Automatic exposure control: Modern machines measure radiation reaching the detector in real time and end the exposure the moment enough signal is collected.
• Easy sharing: Digital images can be transmitted between providers in minutes, eliminating repeat exams caused by lost or unavailable films.

If you have a choice of facilities, those with modern digital equipment—especially ACR-accredited imaging centers—offer the best combination of image quality and low dose.

Questions to Ask Your X-Ray Technologist

Radiologic technologists are trained professionals who answer dose questions every day, and a good one will welcome yours. Consider asking:

• Why is this exam being done, and will the result change my treatment plan?
• Approximately how much radiation does this exam involve, and how does that compare to background radiation?
• Is there a non-radiation alternative, such as ultrasound or MRI, that could answer the same question?
• I had a similar x-ray recently—can you use those images instead of taking new ones?
• Is this facility accredited, and is the equipment digital?
• (If applicable) I am or might be pregnant—how does that affect this exam?
• (For children) Do you use pediatric, child-sized dose protocols?

When the Benefits Outweigh the Risks

It's worth ending where every radiation-safety conversation should: with the benefit side of the equation. An undiagnosed fracture that heals badly, a missed pneumonia, an untreated dental abscess, or an undetected tumor all carry concrete, often serious risks. The theoretical risk from a 0.005-0.1 mSv x-ray, by contrast, is so small it cannot be measured directly even in studies of millions of patients.

When your provider orders an x-ray for a genuine clinical question, the math nearly always favors getting the image. The smart approach to x-ray safety isn't avoiding x-rays—it's avoiding unnecessary x-rays while welcoming the necessary ones, choosing modern accredited facilities, keeping your imaging history handy, and speaking up about pregnancy or recent prior exams. Do those things, and you've captured essentially all of the available safety benefit while losing none of the diagnostic value that makes x-rays one of medicine's most useful tools.

Last Updated: June 12, 2026