Under which circumstance must a radiation protection supervisor be appointed in a dental workplace?

A radiation protection supervisor must be appointed in all workplaces using ionising radiation due to the need for ensuring safety protocols and compliance with regulations pertaining to radiation exposure and management. This role is critical in maintaining safety standards, training staff on safe practices, and ensuring proper procedures are followed to minimize risks associated with ionising radiation.

By appointing a radiation protection supervisor in any setting that utilizes ionising radiation, such as those involved in dental procedures, the workplace can ensure a focused individual is responsible for assessing radiation doses, overseeing protective measures, and ensuring compliance with regulatory guidelines. This appointment is essential across various types of equipment used in dentistry, which includes not only pantomographs and cephalostat machines but also x-ray machines.

In contrast, the other options specify more limited scenarios that do not encompass the broader requirement stipulated by radiation safety guidelines. Hence, the necessity for a supervisor extends beyond individual circumstances to any facility operating with ionising radiation as a comprehensive safety and regulatory measure.