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
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 Basic Radiotherapy Physics and Biology
: Between treatments, both normal and tumor cells begin to grow again. The trick is to ensure the "kill rate" exceeds the "growth rate". Radiotherapy is a cornerstone of modern cancer treatment,
: Modern techniques like IMRT (Intensity Modulated Radiotherapy) and Proton Therapy allow physicists to conform the dose strictly to the tumor, sparing nearby healthy organs like the salivary glands or the liver. 2. The Biology: The "5 R’s" of Radiotherapy David Chang, MD - Ochsner Health : Between
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 .
: These create dense "tracks" of ionization, causing complex, clustered DNA damage that is much harder for a cancer cell to survive. Further Reading
Once the physics delivers the dose, the biology of the cell takes over. The success of treatment is governed by five key biological principles known as the :