Benefit and risk of X-ray diagnostics

X-ray diagnostics is chosen by the doctor when other procedures such as laboratory tests, ultrasound or endoscopy would fail to provide a precise diagnosis. Radiology often is the first procedure to permit or confirm diagnosis or to specify findings.

The following examples illustrate the significance that might be assigned to X-ray diagnostics for individual cases:

• Reliable diagnosis of a bone fracture and check for correct reduction of fracture dislocations.
• Clarification of a head injury following an accident in cases of suspected intracranial bleedings.
• Timely diagnosis of narrowed blood vessels, for example narrowed coronary vessels, by means of angiography, thus reducing the risk of myocardial infarction by an appropriate intervention, such as dilation of the constricted vessel, under fluoroscopic control.
• Early detection of breast cancer in women within the scope of a mammography screening programme.

Radiation risk

In most cases, X-ray examinations involve very low doses. For practical radiation protection purposes it is nonetheless assumed that each X-ray examination is associated with some, albeit low, radiation risk. That is because estimates of radiation risk are usually based on the assumption of a linear non threshold relationship between radiation dose and cancer risk (that is, proportional relationship down to very low doses) although radiation risks cannot be verified in the low dose range.

Radiation risk and age

In radiation risk assessment, it must also be taken into account that the majority of all X-ray examinations are carried out in elderly patients. This is especially true for more dose-intensive procedures, such as computer tomography.

Radiation risk is strongly dependent on age, being – at equal dose – lower for an elderly person than for a younger person. It must also be taken into account that, in particular, severely ill patients receive an above-average number of examinations. The life expectancy of these patients is usually limited and therefore shorter than the latency period of a radiation-induced cancer.

How to reduce medical radiation exposure

• Avoid unnecessary X-ray examinations: An X-ray examination is only useful if the result can prevent or confirm a suspected diagnosis, or if it can affect treatment options.
• Dose optimization: Most types of X-ray examinations are standardized. Each examination is to be optimized in accordance with the principles of radiation protection. As dose limits could reduce the diagnostic benefit, it is currently internationally recommended that no dose limits are to be set for patients undergoing radiological examinations. Nevertheless, physicians are required to carry out each examination in such a way that the radiation exposure for the patient is as low as possible. As a guideline, the Federal Office for Radiation Protection compiles and publishes Diagnostic Reference Levels which should generally not be exceeded in standard examinations in normal weight patients.
• Justification: An X-ray examination is justified if the patient benefits considerably from the examination and, compared with this, the radiation risk is low. According to the German X-ray ordinance, a thorough benefit risk assessment is to be performed. This justification must be carried out by a specialized physician.
• Alternative imaging procedures: Doctors shall also consider procedures associated with low or no radiation exposure if these can provide equal or better information. Every patient should therefore specifically ask why an X-ray examination is necessary and whether or not alternative diagnostic procedures might be applied, for example an ultrasound examination or a magnetic resonance tomography.
• X-ray record card: Medical practices or institutions performing X-ray diagnostics are obliged to keep at hand the so called Röntgenpass (X-ray record card) and to offer it to their patients. The "Röntgenpass" is an important tool to prevent unnecessary repeat examinations and provide a basis for comparison with previously performed examinations.