Basic Radiobiology

Abstract

In recent years, clinical radiotherapy has undergone considerable further development. This was primarily due to technological progress in adapting the radiation fields, the increasing adaptation of cytostatics supplemental to radiation therapy, and, in particular, the increasing introduction of targeted therapies for biological optimization of the radiation effect (See “New Drugs in Radiation Oncology”). New molecular therapies and imaging methods offer unique possibilities for therapy options that are even more closely tailored to the patient. Molecular, targeted therapies specifically exploit the biological differences between tumor and normal tissue (See “Molecular Biomarkers in Radiation Oncology”). They are focused on the alteration of cellular processes in tumors, including cell death, differentiation, signal transduction, proliferation, cell cycle control, and DNA repair mechanisms (See “Molecular Radiation Therapy”). At the end of these cascades, there is always the maximum damage of the tumor cell, in most cases triggered by the damage to the DNA. However, despite these groundbreaking developments, the importance of some fundamental aspects of radiation biology remains important, and others have even been adjusted by new knowledge gains. These include the effect of radiation dependent on linear energy transfer (LET), sublethal (SLD) and potentially lethal damage (PLD), the influence of the fractionation scheme, and the modification of the radiation effect through the presence or absence of oxygen. The following chapter therefore focuses primarily on these radiobiological basics.