A technique used to measure the operator's exposure to radiation is:

Wearing a radiation film badge is a standard practice for monitoring the exposure of operators to radiation in various fields, including dental radiography. These badges contain special film or sensors that measure the amount of radiation exposure over time. When the badge is processed, it provides a record of the radiation dose received by the individual wearing it, ensuring that exposure levels remain within safe limits as determined by health and safety regulations.

This practice is essential for the safety of dental professionals, as consistent exposure to radiation can have harmful long-term health effects. By regularly monitoring exposure with a film badge, operators can make informed decisions about their practices and adhere to recommended safety protocols.

Other options, such as checking fingernail color or counting x-ray series, do not provide a reliable measurement of radiation exposure. These methods lack scientific backing and fail to accurately track the levels of radiation that an operator may absorb during procedures. Furthermore, multiplying the number of films by a fixed number does not account for variations in exposure or the different types of radiographic techniques used, making it an unreliable method for assessing radiation exposure.