Z. Kocak

The Role of Imaging in the Study of Radiation-Induced Normal Tissue Injury

The recognition and assessment of normal tissue injury is an important aspect of radiation oncology practice and a critical endpoint in clinical studies. One of the major challenges in the study of radiation (RT)-induced normal tissue injury is determining the appropriate endpoint. Patients’ symptoms have obvious clinical relevance; however, the scoring of symptoms is relatively subjective. Conversely, radiologic endpoints are potentially quantifiable and are available for objective study. Furthermore, radiologic evidence of sub-clinical normal tissue injury is far more common than are clinical symptoms, providing a larger number of patients with identifiable injury for study. We review herein radiologically-detected normal tissue injury as it relates to the lung, heart, brain, and salivary glands. The concepts described are likely to be similar for other organs. We conclude that: (1) radiologically-defined normal tissue injury in human patients may be related to longterm, clinically meaningful injury, but further study is needed to better quantify this association;