Which of the following would be most likely to cause the greatest skin dose?

A short source-to-skin distance (SID) is the factor most likely to cause the greatest skin dose because it refers to the proximity of the X-ray source to the skin. When the distance is minimized, the intensity of the radiation striking the skin is significantly increased due to the inverse square law, which states that the intensity of radiation is inversely proportional to the square of the distance from the source. Therefore, a shorter SID means that more radiation photons will reach the skin, resulting in a higher skin dose.

In contrast, high kilovoltage tends to increase the penetration ability of the X-ray beam but may not significantly contribute to skin dose since it primarily affects deeper tissues rather than the skin surface. Increased filtration helps remove low-energy photons from the beam, which are mostly absorbed by the skin and do not contribute to the diagnostic image, thus reducing skin dose. Decreased milliamperage results in lower X-ray production, leading to a lower overall radiation dose, including skin dose. Therefore, the option referring to a short source-to-skin distance is the most relevant factor for increasing skin dose.