What skin effect may occur if a patient receives 20 Gy to their skin?

When a patient receives a dose of 20 Gy to the skin, the most likely outcome is the development of reddish patches that may clear up after about two weeks. This dose is significant and falls within the range that can cause acute radiation skin reactions. Following radiation exposure, the skin can exhibit an inflammatory response, characterized by erythema (reddening of the skin) as the tissues respond to the damage caused by the radiation.

The timeline for these reactions can vary, but erythema resulting from this level of exposure typically appears shortly after irradiation and may resolve within a couple of weeks, depending on the individual's skin type and the extent of damage. This transient reaction aligns with the observed effects for doses around this magnitude, as the skin has a remarkable ability to repair itself after such exposure.

Other choices describe more severe outcomes, such as immediate blistering, which typically corresponds to higher radiation doses and indicates more severe skin damage. Skin peeling could occur, but it is more common at slightly different dose levels or in more sustained exposure scenarios. Permanent scarring is associated with even higher doses and prolonged damage, not simply a single dose of 20 Gy. Hence, the most appropriate effect corresponding to the dose mentioned is the appearance of reddish patches that