Which set of exposure factors would typically result in the lowest patient dose?

Which set of exposure factors would typically result in the lowest patient dose?

• A. Low mAs, high kVp
• B. High mAs, low kVp
• C. Low mAs, high kVp, small focal spot
• D. Low mAs, high kVp, large focal spot

Answer: (A)

Minimizing patient dose comes from using the smallest amount of radiation that still yields a usable image. The most effective way to achieve this is to use a high kVp so the beam is more penetrating, which lets you lower the tube current and exposure time (mAs) while maintaining receptor exposure. In practice, lower mAs reduces dose directly, and higher kVp allows that reduction without sacrificing the image enough to require more exposure. The focal spot size affects image sharpness and heat load but does not significantly change the dose to the patient. So, a combination of low mAs with high kVp gives the lowest typical patient dose.

Minimizing patient dose comes from using the smallest amount of radiation that still yields a usable image. The most effective way to achieve this is to use a high kVp so the beam is more penetrating, which lets you lower the tube current and exposure time (mAs) while maintaining receptor exposure. In practice, lower mAs reduces dose directly, and higher kVp allows that reduction without sacrificing the image enough to require more exposure. The focal spot size affects image sharpness and heat load but does not significantly change the dose to the patient. So, a combination of low mAs with high kVp gives the lowest typical patient dose.