Flattening filters are unnecessary for which type of radiation units?

Flattening filters are used in high-energy photon radiation therapy to produce a more even dose distribution across the treatment area. In contrast, 60Co (Cobalt-60) units inherently produce a uniform beam profile and dose distribution due to the nature of the radiation they emit. The gamma rays from 60Co originate from a source that naturally provides a relatively flat dose distribution, therefore, there is no need for additional flattening filters to ensure uniformity.

In medical dosimetry, flattening filters can introduce complications such as increased complexity in delivery and potential for dose inhomogeneity in certain scenarios. Since 60Co units do not require these filters, they simplify the treatment process while still delivering effective therapy, which is why they are considered unnecessary in this context.

This principle stands in contrast to kV units, high-energy photon units, and low-energy photon units, where flattening filters are typically employed to address specific dose distribution challenges inherent in their radiation outputs.