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X-Ray Safety Leaflet

X-Ray Safety Leaflet


HOW SAFE ARE THEY? 
Patients are sometimes concerned about the possible harmful effects of radiation. This section will explain the risks and put them into perspective.

All the methods of medical imaging can bring very real benefits to patients. The overriding concern of your doctor and the radiology department is to ensure that when radiation is used, the benefits from making the right diagnosis and consequently giving you the right treatment, outweigh any small risk involved. If, after reading this leaflet, you are still concerned about the possible risks from having an X-ray examination, ask your doctor how the information gained will help to improve your treatment. If treatment decisions depend on the findings, then the risk to your health from not having the examination is likely to be much greater than that from the radiation itself.

X-RAY DOSES IN PERSPECTIVE
We are all exposed to natural background radiation every day of our lives. This comes from the ground and building materials around us, the air we breathe, the food we eat and even from outer space (cosmic rays). 

Each medical X-ray or nuclear medicine examination gives us a small additional dose on top of this natural background radiation. The level of dose varies with the type of examination, ranging from the equivalent of a few days of natural background radiation for the commoner examinations such as xrays of the chest or limbs,  to a few years, as shown in the table below. Even these represent only a fraction of our lifetime dose from natural radiation.

WHAT ARE THE EFFECTS OF RADIATION?

You will be glad to know that the radiation doses used for X-ray examinations or isotope scans are many thousands of times too low to produce immediate harmful effects, such as skin burns or radiation sickness. The only effect that is known to be possible at these low doses is a very slight increase in the chance of cancer occurring many years or even decades after the exposure. Approximate estimates of the chance or risk that a particular examination or scan might result in a radiation-induced cancer later in the lifetime of the patient are shown in the last column of the table.

 

 

X-ray examination (Nuclear medicine or isotope scan)

Equivalent period of natural background radiation

Lifetime additional risk of cancer per examination*

Chest

a few days

NEGLIGIBLE RISK
Less than
1 in 1,000,000

Teeth

Arms and legs

Hands and feet

Skull

A few weeks

MINIMAL RISK
1 in 1,000,000
to 1 in 100,000

Head

Neck

Breast

A few months
to a year

VERY LOW RISK
1 in 100,000
to 1 in 10,000

Hip

Spine

Abdomen

Pelvis

CT sdan of head

(Lung isotope scan)

(Kidney isotope scan)

Kidneys and bladder (IVU)

A few years

LOW RISK
1 in 10,000
to 1 in 1,000

Stomach - barium meal

Colon - barium enema

CT chest

CT abdomen

(Bone isotope scan)

* These risk levels represent very small additions to the 1 in 3 chance we all have
of getting cancer

 

RADIATION RISKS IN PERSPECTIVE

Just about everything we do in our daily lives carries some level of risk. We tend to regard activities as being “safe” when the risk of something unpleasant happening falls below a certain level.

The lower the level of risk, the “safer” the activity becomes. For example, most people would regard activities involving a risk of below 1 in 1,000,000 as exceedingly safe.

The radiation risks for simple X-ray examinations of the teeth, chest or limbs, can be seen to fall into this negligible risk category (less than 1 in 1,000,000 risk). More complicated examinations carry a minimal to low risk.

Higher dose examinations such as barium enemas, CT body scans or isotope bone scans fall into the low risk category (1 in 10,000 to 1 in 1,000 risk). As we all have a 1 in 3 chance of getting cancer even if we never have an X-ray, these higher dose examinations still represent a very small addition to this underlying cancer risk from all causes.

As long as it is clearly necessary to help make the correct treatment decision for a patient, the benefits from any X-ray examination or isotope scan usually outweigh these small radiation risks. It should be remembered that the higher dose examinations are normally used to diagnose more serious conditions when a greater benefit to the patient is to be expected

RADIATION RISKS FOR OLDER AND YOUNGER PATIENTS

As you get older you are more likely to need an X-ray examination. Fortunately radiation risks for older people are lower than those shown in the table above. This is because there is less time for a radiation-induced cancer to develop, so the chances of it happening are greatly reduced.

Children, however, with most of their life still ahead of them, may be at twice the risk of middle-aged people from the same X-ray examination. This is why particular attention is paid to ensuring that there is a clear medical benefit for every child who is X-rayed. The radiation dose is also kept as low as possible without detracting from the information the examination can provide.

A baby in the womb may also be more sensitive to radiation than an adult, so we are particularly careful about X-rays during pregnancy. There is no problem with something like an X-ray of the hand or the chest because the radiation does not go anywhere near the baby. However, special precautions are required for examinations where the womb is in, or near, the beam of radiation, or for isotope scans where the radioactive material could reach the baby through the mother’s circulating blood.

If you are about to have such an examination and are a woman of childbearing age, the radiographer or radiologist will ask you if there is any chance of your being pregnant.   If this is a possibility, your case will be discussed with the doctors looking after you to decide whether or not to recommend postponing the investigation. There will be occasions when diagnosing and treating your illness is essential for your health and your unborn child. When this health benefit clearly outweighs the small radiation risks, the X-ray or scan may go ahead after discussing all the options with you.


RADIATION RISKS FOR FUTURE GENERATIONS

If the reproductive organs (ovaries or testes) are exposed to radiation there is a possibility that hereditary diseases or abnormalities may be passed on to future generations. Although the effect has never been seen in humans, lead-rubber shields can be placed over the ovaries or testes during some X-ray examinations, as a precaution. They are only necessary for examinations of the lower abdomen and thighs on patients who are young enough to have children. Even then, there are some examinations where it is not practicable to use gonad shields since they will obscure important diagnostic information.


IMPORTANT POINTS TO REMEMBER

  • In radiology departments every effort is made to keep radiation doses as low as possible
  • The radiation doses from X-ray examinations or isotope scans are small in relation to those we receive from natural background radiation
  • The health risks from these doses are very small in relation to the underlying risks of cancer, but are not entirely negligible for some procedures involving fluoroscopy or computed tomography (CT).
  • The risks are much lower for older people and a little higher for children and unborn babies, so extra care is taken with young or pregnant patients.
  • If you are concerned about the possible risks from an investigation using radiation, you should be aware that most of the time the risk to your health from not having the examination is likely to be very much greater than that from the radiation itself.
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