CAMRT Radiography Practice Exam

If all other factors remain the same, how does increasing tube current affect patient dose?

1. Increased tube current = Decreased dose

2. Increased tube current = No change in dose

3. Increased tube current = Increased dose

4. Increased tube current = Variable dose

The correct answer is: Increased tube current = Increased dose

Increasing the tube current directly increases the quantity of X-ray photons produced during an imaging procedure. As the tube current, measured in milliamperes (mA), is raised, more electrons are emitted from the filament of the X-ray tube, which in turn leads to a higher number of X-ray photons being generated. Since the amount of radiation exposure received by a patient is correlated with the number of X-ray photons that reach them, a higher tube current results in a higher patient dose. It's important to recognize that this relationship is generally linear; doubling the tube current roughly doubles the dose delivered to the patient, assuming all other imaging parameters remain constant. This understanding of tube current and its effect on patient dose is fundamental in radiography, as it emphasizes the importance of optimizing radiation exposure to ensure patient safety while achieving the necessary diagnostic quality in imaging.