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Every X-ray and nuclear medicine examination is associated with radiation exposure for the patient. This should be kept as low as possible. However, the corresponding measures to reduce radiation exposure must also be practicable. The most important aspects that help to minimize radiation exposure are

• a careful indication for the examination
• high-quality technical equipment
• good training and experience of the staff

Our clinic meets these and other requirements.

Natural and civilization-related radiation exposure

Humans are exposed to various types of radiation (e.g. light, UV, radio waves, radiation from X-ray equipment and radioactive sources). X-rays belong to the group of ionizing radiation (radiation that can remove electrons from atoms and leave ions behind). When radiation hits the body, some of it is absorbed in the tissue - the amount of radiation absorbed is described by the term dose.

Different radiation exposures can be compared by specifying the so-called effective dose (unit: milli-Sievert, abbreviated to mSv). This provides a measure of the radiation risk to the exposed person. The natural radiation to which all living beings are exposed can be used for comparison. For the Swiss population, the four natural radiation components (cosmic and terrestrial radiation, incorporated radionuclides, radon with by-products) lead to an average effective dose of around 4 mSv/year, whereby the fluctuation range from 1 to around 150 mSv is very large. Civilization's radiation exposure, on the other hand, averages 1.2 mSv/year, almost all of which comes from medicine. Overall, the average radiation exposure of a living being in Switzerland is therefore around 5 mSv/year.

Most X-ray and nuclear medicine examinations, such as images of the lungs, skull and extremities, involve small doses; they belong to the so-called low-dose range. X-rays of the peripheral extremities, including the elbow and upper ankle, are also not considered dose-intensive diagnostic applications.

Dose-intensive X-ray and nuclear medicine examinations

Other examinations count as dose-intensive applications, e.g. X-ray examinations of the axial skeleton (cranial bones, spinal column, pelvis), pelvis and abdomen (stomach) as well as examinations in which several image slices are taken (conventional tomography, computer tomography). Fluoroscopy, fluoroscopy-supported contrast medium examinations and interventions also belong to the group of dose-intensive examinations. In the case of dose-intensive X-ray examinations, the effective dose is generally greater than 0.5 mSv.

Similarly, the effective dose for numerous nuclear medicine examinations is more than 0.5 mSv.

The figures in the following list are typical doses in mSv, which are to be regarded as guide values for the magnitude of the medical radiation exposure in question. Larger individual differences may occur depending on the exposure technique and the constitution, sex and age of the patient.

In contrast to closed radiation sources, such as those used for X-ray examinations, more extensive safety measures are required when handling open radioactive sources due to the risk of contamination.

In order to monitor individual radiation exposure, triage measurements are carried out daily for employees who carry out nuclear medicine examinations and treatments and therefore work with open radiation sources (doctors, laboratory technicians, medical-technical radiology specialists, biomedical analysts, nursing and cleaning staff).

Radioactive waste (e.g. waste water from the ward) must be disposed of responsibly. The Radiopharmaceutical Chemistry and Nuclear Medicine departments are jointly responsible for testing, measuring and disposing of radioactive waste.

Important prerequisites for optimal radiation protection are the safety and proper functioning of X-ray equipment and nuclear medicine devices and accessories. Well-trained specialists, in particular medical-technical radiology specialists (MTRAs), ensure that any malfunctions and deviations are detected in good time.

During commissioning, a quality assurance program checks that the equipment is functioning properly. An acceptance test must be carried out before a medical system or imaging system is used for the first time, followed by periodic constancy tests. Maintenance and subsequent status checks are also carried out regularly. Aids such as lead aprons are checked for their condition at fixed intervals and repaired or replaced if necessary.

At the University Hospital Basel, we naturally carry out the various checks in accordance with radiation protection legislation. We even check individual devices and utensils more frequently than prescribed in order to ensure optimum radiation protection.

Through their behavior, patients can help to ensure that a necessary X-ray examination provides good quality results with as little radiation as possible. Wherever possible, it must be avoided that an examination has to be repeated. Patients can contribute to an optimal X-ray examination by taking the following measures:

• Follow the instructions of the staff
• avoid movement during an X-ray (unless instructed to do so)
• remove jewelry, hair clips, watches, etc. during examinations in the corresponding body area
• draw the staff's attention to special features (e.g. implants)
• bring previous X-ray images with you or draw your attention to them
• Take your X-ray passport with you (if available)

Holding patients in place

Certain patients (e.g. children, frail or elderly patients) may need to be supported or held during the X-ray examination in order to obtain a high-quality X-ray image. Professionally exposed persons (medical-technical radiology specialists, doctors, etc.) may only hold children, unsteady or unstable patients if they cannot be restrained during the X-ray examination and no other persons are available to hold them. Relatives or nursing staff must be called in primarily for this purpose. Persons holding patients must use appropriate protective equipment (aprons).

The radioactive material used at the University Hospital Basel is disposed of responsibly. The Departments of Radiopharmaceutical Chemistry and Nuclear Medicine are responsible for this. We check that waste is stored safely until its radioactivity has decayed and collect radioactive waste water, for example from the nuclear medicine ward (from toilets, washbasins and showers), in separate tanks.

Only when the radiation has reached the limits prescribed by the Federal Office of Public Health (FOPH) do we arrange for the disposal of the now harmless material.

In addition, we take weekly samples of the wastewater from the entire University Hospital Basel and test them for radioactivity.