IN SHORT
Children and foetuses are more sensitive to radiation than adults. You should therefore tell the radiographer performing the examination if you are pregnant.
If you have an X-ray examination while you are pregnant, the radiation dose will be considerably lower than the level that would lead to risk of acute injury to the foetus.
The risk of radiation injuries decreases with age, and elderly people are less likely to develop cancer caused by radiation.
Pregnant women and X-rays
Children and foetuses are more sensitive to radiation than adults. You should therefore tell the radiographer performing the examination if you are pregnant. Unless X-rays of your pelvis or stomach is to be taken, pregnancy will not normally contraindicate the examination.
If you have an X-ray examination when you are pregnant, the radiation dose will be considerably lower than the level that would lead to risk of acute injury to the foetus. To reassure you, it can be a good idea for the radiology department to assess the radiation dose.
Benefits and risks
Ahead of the procedure, the doctor who referred you and the department that performs the examination will assess the benefits and risks associated with the procedure. X-rays often need to be taken in order to detect any disease or assess the effects of treatment. In these cases, the benefits of the procedure will outweigh the associated radiation risk. Once it has been decided that X-rays should be taken, it is important that the procedure is performed with the lowest possible radiation dose and an image quality which is sufficient to ensure an accurate assessment.
The risk of radiation injury decreases with increasing age, and older people, who account for the largest patient group, are at less risk of developing cancer caused by radiation. Children, who are still growing, undergo rapid cell divisions in most of their body tissues and are therefore more sensitive to radiation than adults. They also have more years of life expectancy, so it is essential to minimise the radiation exposure of children. The radiation dose and image quality of X-rays are adapted to take the age and the patient’s disease/injury into account, and there are often separate procedures for paediatric examinations.
Risks associated with some common X-ray procedures
To give an indication of the approximate level of risk associated with various types of X-rays, the table below compares radiation doses with the mean background radiation.
‘Natural background radiation’ is radiation which is around us at all times. This radiation mainly originates from radon and thoron in the air, from natural occurrences in food and drink, soil and buildings, and from space. The natural background radiation level is approximately 4.1 millisievert per year (mSv/year), but this varies from place to place, partly as a result of different radon levels.
The table below shows the additional risk of developing cancer as a result of various examinations.
| X-ray examination | Effective dose* [mSv] |
Corresponding period of natural background radiation | Additional risk of developing cancer** |
|---|---|---|---|
| Bone density measurement Teeth Lungs Arms and legs Hands and feet Neck |
< 0.1 mSv | A few days | Insignificant risk Less than 1 in 1,000,000 |
| Head Mammography Pelvis/hips |
0.1 – 1.0 mSv | A couple of weeks | Minimal risk 1 in 1,000,000 to 1 in 100,000 |
| Back Stomach Most CT scans Assessment of the blood vessels in the heart |
1 – 10 mSv | A couple of months to one year | Very low risk 1 in 100,000 to 1 in 10,000 |
| CT scan of the urinary tract Some CT scans for cancer diagnosis and monitoring Some operations |
10-20 mSv | A couple of years | Low risk 1 in 10,000 to 1 in 1,000 |
* The unit used to measure effective radiation dose is the Sievert, but we often use the millisievert (mSv) for practical reasons.
** This is a very small risk in addition to the natural risk of approximately 30% which everyone has of developing cancer at some time in their life. The risk also depends on the age of the patient.
DSA compares radiation doses from various examinations at different hospitals and X-ray institutes, so that we can establish the right dose range for different types of examinations. Guidelines are issued on the basis of the collected dose data, and personnel who carries out the examinations are required to follow DSA’s guidelines.