What factor controls the quantity of x-rays produced?

The quantity of x-rays produced in an x-ray tube is primarily controlled by the milliampere-seconds (mAs). This measurement represents the product of the tube current (measured in milliamperes, mA) and the duration of exposure (measured in seconds). Essentially, increasing the mAs will increase the number of x-ray photons generated, which results in a higher quantity of x-rays reaching the film or digital detector.

In practical terms, higher mAs values correlate with greater x-ray exposure and subsequently a darker image on a radiograph, assuming all other settings remain constant. Therefore, mAs is a critical factor to consider when trying to adjust the quantity of x-rays produced for optimal image quality.

While other factors listed, like kVp (kilovoltage peak), affect the energy and penetration of the x-rays, they do not directly control the quantity of x-rays produced. Exposure time is a component of mAs, but it does not function independently to determine x-ray quantity. Filtration, on the other hand, involves the removal of lower-energy x-rays from the primary beam and does not increase the number of x-ray photons produced. Hence, mAs is indeed the determining factor in controlling the quantity of x-rays