Radiation ulcers are wounds caused by the acute or chronic effects of ionizing radiation. The injury may involve the skin, underlying soft tissue, and even deeper into bones.
Given the progressive nature of radiation damage, a soft-tissue ulceration may develop at any time after radiation exposure. This ulceration may be large, or it may initially manifest as a draining sinus. There are three types of radiation injuries: acute, subacute, and chronic.
Acute injury - The effects on the skin and exposed soft tissues are similar to a thermal burn, causing alterations and destruction of the epidermis' basal cells. With acute injury, these radiation ulcer effects are slower and more progressive than those caused by thermal burns.
Acute injury results in erythema, a reddening of the skin that may be recurrent. Along with erythema, the patient has pain, edema (excessive fluid buildup), itching, and eventual desquamation (the loss of bits of outer skin by peeling, shedding or scaling). Desquamation can progress to the death of soft tissue (necrosis) and obliterative endarteritis (an extreme degree of artery inflammation.)
Subacute Injury - Subacute injury causes cutaneous erythema and edema, but the erythema tends to be transient and necrosis is usually absent. Another characteristic finding after multiple radiation treatments is hyper pigmentation and a woody hardening of the soft tissues.
Chronic Injury - The injuries are similar to subacute injuries, but are more pronounced. This is particularly true of vascular damage. Fibrosis and thrombosis progress to obliterative endarteritis and its attendant ischemia.
Mostly commonly, radiation injury is an adverse effect of therapeutic radiation therapy. Other causes are occupational or environmental exposures.
Regardless of the source of the radiation, radiation injury to tissue is caused by the interaction of the radiation energy with DNA that causes structural damage to the DNA. Depending on the precise area of injury in the cell, the damage may be repaired, cause cell death, or cause delayed effects. This damage can lead to both acute and chronic tissue effects.
Acute injury refers to radiation exposure that often occurs in a setting such as an industrial accident. Acute Injury is usually caused by orthovoltage radiation in the range of 5000-10,000 rads.
Subacute injury is caused by recurrent exposures to lower-energy radiation over time, such as therapeutic radiation. This type of radiation tends to be of lower energy than in occupational or environmental exposures.
Chronic Injury results from long-term exposures, typically from repeated, occupational exposures (i.e., radiology technicians).