What is the air kerma rate of a 60 cobalt beam at 1 m from the source for a 10 cm x 10 cm field?

The air kerma rate of a 60Co beam at 1 meter from the source is a critical parameter in radiation therapy, particularly for understanding dose delivery during treatment. The selection of 100 cGy/min as the correct answer reflects the established average output for a 60Co source operating under typical conditions with a 10 cm x 10 cm field at the specified distance.

In this context, 'air kerma' refers to the kinetic energy released in air due to ionizing radiation, which is an important factor when measuring radiation dose rates. The 60Co source emits gamma rays, which have specific energy characteristics that influence the air kerma rate. Typically, the air kerma rate is standardized under clinical conditions, and for 60Co therapy units, an output around 100 cGy/min is commonly observed when measurements are taken at 1 meter for a standard field size.

Understanding the output related to different field sizes and distances is essential for dosimetrists, as changes in these factors can result in different air kerma values. This understanding allows for accurate calculations needed for treatment planning and dose administration in radiation therapy.

In this instance, the knowledge of the 60Co beam characteristics and the standardized treatment parameters contribute to the conclusion