Bone

Radiation doses above 60 Gy kill endothelial cells. The loss of endothelial cells will cause obliterative endarteritis and periarteritis. Also, it will overwhelm the reparative capacity of bone. As a result, osteoblasts and osteocytes undergo necrosis, and the periosteum and marrow spaces undergo fibrosis. Consequently, the irradiated bone becomes hypocellular, hypovascular, and hypoxic. The potential clinical outcome of these effects is osteoradionecrosis. (Figure 11).¹³

Figure 11.

Figure 11.

Chronic radiodermatitis and ulceration and osteoradionecrosis of the mandible.

The effect of radiotherapy on the developing bone of a child depends on the child’s age during treatment, the quality and quantity of the radiation dose delivered, and the location and extent of the bone in the treatment field. Doses over 20 Gy may significantly impair bone growth and development, resulting in maxillary and mandibular hypoplasia. In addition, the use of asymmetrical radiation portals may lead to hemifacial hypoplasia.¹³