Radiation Oncology/Radiobiology/Normal Tissue Tolerance

• Normal tissue radiation tolerance refers to the response of previously unirradiated tissues to a variety of very different exposure scenarios:
  1. Early radiation effect: typically, tissues with a high proliferative activity, such as bone marrow, epidermis, or mucosa of the gastro-intestinal tract, display early radiation effects
  2. Late radiation effect: observed in virtually all tissues and organs, usually irreversible, and potentially progressive over long time periods

Volume effect and normal tissue complication probability (NTCP) models

• The probability that a given dose of radiation will cause an organ or structure to experience complications considering the specific biological cells of the organ or structure
• The NTCP is used in treatment planning as a tool to differentiate among treatment plans
• A dose-dependent mathematical model to gauge the probability of dose-induced complications in noncancerous tissue

QUANTEC (Quantitative Analysis of Normal Tissue Effects in the Clinic, PMID: 20171515)