Investigation of skin dose in megavoltage radiation therapy for breast cancer.

Dermatitis and skin reactions are frequently associated with whole breast radiotherapy (WBRT). The severity of the skin damage depends on many factors such as x-ray beam energy, radiation therapy technique, breast size and shape, existence of skin folds, total radiation dose and dose per fraction. Dermatitis can vary from dryness to a severe skin reaction such as moist desquamation or ulceration. Radiation dermatitis may affect the quality of life or treatment outcome in extreme cases. The most severe skin reactions generally occur in skin folds due to dose buildup effects in megavoltage photon beams. Although modern radiation therapy techniques have been shown to reduce skin dose, in some patients, the skin still receives a higher radiation dose than necessary. B positioning during radiation therapy to reduce skin folds may provide further reduction in unnecessary skin dose. Furthermore, better breast positioning may also lead to reduction in the volume of normal tissues irradiated, further benefitting the patient. This thesis is an investigation of the impact of breast position on radiation dosimetry at the skin surface in megavoltage x-ray beams for intensity modulated radiation therapy. Radiological properties of potential materials for construction of a breast positioning device are studied.Science, Faculty ofPhysics and Astronomy, Department ofGraduat