Which of the following is NOT an advantage of a 60 Co unit in radiation therapy?

The focus of the question is to identify the characteristic that does not provide an advantage for the use of a cobalt-60 (60 Co) unit in radiation therapy.

Cobalt-60 is known for several key advantages in the context of radiation therapy. The high gamma energy emitted by cobalt-60 makes it effective for treating deep-seated tumors, as it can penetrate tissue more effectively than lower-energy radiation sources. High specific activity means that cobalt-60 can deliver a significant dose of radiation while being used in smaller amounts, which is beneficial in clinical settings. The reasonably long half-life of 60 Co (approximately 5.27 years) allows for the source to be used over an extended period before it needs to be replaced, making it practical for facilities relying on this type of equipment.

However, when it comes to low cost, this is not considered an inherent advantage of cobalt-60 units. While the cost may vary depending on the specific makes and models of radiation therapy equipment, cobalt-60 sources are often more expensive compared to other more modern radiation therapy options, such as linear accelerators. Therefore, characterizing low cost as an advantage does not accurately reflect the comparative financial aspects involved in using cobalt-60 in radiation therapy.