The units for the AKS of a brachytherapy source are which of the following?

The correct answer is expressed in the unit Gy m² h⁻¹, which is a measure of the air kerma strength (AKS) of a brachytherapy source. The air kerma strength is crucial for understanding the dose delivered by the radiation source and is defined as the rate of energy transferred from ionizing radiation to air per unit area.

In the context of brachytherapy, the AKS specifically quantifies how much energy is deposited in a specific volume of air around the source over time, considering the spatial distribution of the radiation emitted. This is particularly important for treatment planning, as it helps in assessing the dose that will be delivered to the tumor while minimizing exposure to surrounding healthy tissue.

The unit Gy m² h⁻¹ combines the dose (in grays), the distance squared (in square meters), and the time (in hours), allowing for a practical representation of how brachytherapy sources function in a clinical setting. Accurate knowledge of AKS is vital for ensuring safe and effective radiation therapy delivery, especially given the precise control needed in brachytherapy applications.

Other units listed do not correctly reflect the standardized way of measuring air kerma strength for brachytherapy sources. For instance, Gy/cm²/h also gives