How is entrance skin exposure (ESE) affected when milliamperes (mA) are increased while the source-to-skin distance (SSD) is also increased?

Entrance skin exposure (ESE) is a measure of the radiation dose that the skin receives when subjected to a radiological procedure. It is influenced by several factors, including milliamperes (mA) and the source-to-skin distance (SSD). When the mA is increased, the quantity of radiation generated is higher, leading to increased dose rates at the skin. However, as SSD increases, the intensity of the radiation reaching the skin decreases due to the inverse square law.

The inverse square law states that radiation intensity diminishes with the square of the distance from the source. Therefore, while higher mA would typically increase the ESE, the simultaneous increase in SSD counteracts this effect by significantly reducing the amount of radiation that actually reaches the skin.

When both the mA and the SSD are increased, the overall effect tends to result in a decrease in ESE due to the stronger influence of the increased distance on radiation intensity reaching the skin. Thus, when evaluating the combined effects of increased mA and increased SSD, ESE is likely to decrease overall.