Basic Radiotherapy Physics And Biology Apr 2026

: These deposit energy sparsely. Most of their damage is indirect and easily repairable by healthy cells.

Radiotherapy primarily uses high-energy , such as X-rays, gamma rays, protons, and electrons. Unlike visible light, this radiation carries enough energy to knock electrons out of atoms, a process called ionization .

: Oxygenated cells are about three times more sensitive to radiation than hypoxic (oxygen-poor) ones. As a tumor shrinks, previously hidden hypoxic areas get better blood flow and become easier to kill. Basic Radiotherapy Physics and Biology

: The radiation hits water molecules in the cell, creating reactive oxygen species (free radicals) that then attack the DNA.

Not all radiation is created equal. The describes how much energy a particle deposits as it travels through tissue: : These deposit energy sparsely

: Between treatments, both normal and tumor cells begin to grow again. The trick is to ensure the "kill rate" exceeds the "growth rate".

For those looking to master these concepts, the textbook Basic Radiotherapy Physics and Biology by and colleagues is a widely used resource for residents and medical professionals. It provides a concise review of these topics, including the linear-quadratic (LQ) model used to predict cell survival. David Chang, MD - Ochsner Health Unlike visible light, this radiation carries enough energy

Radiotherapy is a cornerstone of modern cancer treatment, utilized by approximately 50% of all cancer patients. But how does a beam of energy actually "cure" a disease? The answer lies at the intersection of —the science of how energy interacts with matter—and radiation biology —the study of how living cells respond to that energy. 1. The Physics: Interaction of Radiation with Matter