Depth dose in skin for obliquely incident⁶⁰Co radiation

Abstract

Clinical observations show that much of the skin-sparing effect of 60Co radiation is lost if the beam is incident obliquely on the skin. This is most evident with tangential irradiation. LiF thermoluminescent powder was used to determine the build-up of dose in the superficial layers of skin of a tissue-equivalent phantom. Dose measurements at several skin depths were made for various values of angle of incidence, field size and SSD. The dose to the basal layer of the epidermis increases with increase in both field size and angle of incidence, but is independent of epidermal thickness. The maximum dose to the dermis occurs for angles of incidence between 60 deg. and 90 deg. and varies little with field size and dermal thickness. These results can be related to observed skin reactions.