Radiation shielding of X-ray rooms in health care and veterinary practice
Radiation is produced momentarily during X-ray imaging. Typically, X-ray images are taken in a separate imaging room, which is designed so that practically no radiation leaves the room. Therefore, the risks caused by X-ray radiation to workers and members of the public can be typically kept to a very low level.
Premises where radiation sources are used have to be planned and implemented in such a way that the occupational exposure and public exposure is as low as possible when reasonable actions are implemented. Exposure shall, at least, not exceed the dose constraint set for the applicable group of persons, which is typically 0.1 millisieverts (mSv) per year for members of the public and 0.3 mSv per year for occupational exposure outside the premises of use. Radiation shielding is implemented by using a material in the shielding that reduces the radiation dose rate. When assessing the need for radiation shielding, the following factors could be taken into account:
- the type of equipment or radiation source and the characteristics of the radiation used
- the workload of the equipment or radiation source
- the direction and size of the radiation beam
- the location of the equipment or source in the room
- the intended purpose of the space behind the shields.
Structural shielding is often implemented by using lead, which is why the need for shielding is presented in millimetres of lead (mmPb). However, it is often more practical to implement structural shielding with other building materials, especially in the case of sources that produce lower radiation exposure. For this purpose, lead equivalent values for different radiation energies have been determined for different building materials.
The level of radiation shielding of the room’s doors and windows, including their frames, must be equal to that required from the surrounding wall. Attention should also be paid to larger penetrations, such as ventilation ducts. Particular attention has to be especially paid if people can occupy spaces behind them.