Computed Tomography Technologist Practice Exam 2025 – All-in-One Guide for Exam Success!

The Gray (Gy) is the SI unit of absorbed dose, which specifically quantifies the amount of energy deposited by ionizing radiation in a unit mass of matter, typically human tissue. One Gray is defined as the absorption of one joule of radiation energy by one kilogram of matter. This measurement is crucial in fields such as radiation therapy, where understanding the dose absorbed by tissues is essential for effective treatment while minimizing damage to surrounding healthy tissues.

The other choices refer to different concepts that are unrelated to the Gray. For instance, blood volume pertains to the total volume of blood in the body and is measured in milliliters or liters, while radiation exposure measures the quantity of radiation passing through a specific area, often quantified in terms of roentgen. Serum concentration applies to the quantity of a substance in the serum and is typically given in moles per liter. Each of these has distinct units and applications, reinforcing that the Gray specifically measures absorbed dose.