The total of air kerma over the exposed area of the patient is called:

• A. Dose area product
• B. Mean marrow dose
• C. Genetically significant dose
• D. Total patient dose

Answer: (A)

The idea being tested is that the overall radiation burden to a patient during an exposure is captured by multiplying the dose at a point (air kerma) by the area over which the beam is incident. This product, called the Dose Area Product, represents the total energy delivered to the patient taking into account both how strong the beam is and how large the exposed field is. It’s expressed in Gy·cm^2 and is useful for comparing procedures and estimating stochastic risk because it reflects both dose and field size. Other terms describe different concepts: mean marrow dose refers to an average dose to bone marrow, not the total energy delivered; genetically significant dose is a population-based metric of genetic risk; total patient dose isn’t a standard single-parameter measure used clinically.