Which dose metrics are used to assess patient dose, and which metric is used for population risk estimates?

• A. The imaging system's exposure index value defines dose.
• B. Entrance Skin Dose (ESD) and Dose-Area Product (DAP); effective dose (mSv) is used for population risk estimates.
• C. Grayscale value and image brightness determine dose.
• D. Body mass index and age determine dose.

Answer: (C)

In radiography, the amount of radiation a patient actually receives is quantified with metrics that reflect how the beam interacts with the body. Entrance Skin Dose (ESD) measures the dose at the skin entry point, giving a direct sense of potential skin exposure from the exam. Dose-Area Product (DAP) combines that dose with the size of the exposed area, providing a metric that correlates with the total energy delivered to the patient and is useful for comparing procedures and protocols. For assessing risk to populations, the standard metric is effective dose, expressed in millisieverts, which weights the radiation absorbed by different tissues according to their sensitivity to radiation. This allows comparisons of stochastic risk across different exams and patient groups. Grayscale value and image brightness describe image quality, not how much radiation the patient receives, and BMI or age do not themselves define a dose metric. So, the appropriate pairing is that patient dose is assessed with ESD and DAP, while population risk estimates are based on effective dose.