What is the primary purpose of an added filter used with a teletherapy kV unit?

The primary purpose of an added filter in teletherapy kilovolt (kV) units is to achieve desired filtration for therapeutic purposes. In radiation therapy, filters are employed to modify the beam of energy before it reaches the patient. This is essential for ensuring that the beam is optimally shaped and designed to deliver the appropriate dose to the target tissue while sparing surrounding healthy tissues.

Filtration plays a crucial role in patient safety and treatment efficacy. By filtering out lower-energy photons that do not contribute significantly to the therapeutic effect and may increase the dose to surrounding healthy tissue, the added filter helps in optimizing the radiation quality. This improves the overall therapeutic ratio, ensuring that more of the radiation is effective at treating the tumor while minimizing excess exposure to neighboring healthy areas.

Other options, such as enhancing image quality, increasing patient dose, or reducing exposure time, are not aligned with the primary function of the filters in this context. The added filtration is specifically focused on refining the therapeutic capability and effectiveness of the radiation delivered.