Basic Radiotherapy Physics And Biology Access

: These create dense "tracks" of ionization, causing complex, clustered DNA damage that is much harder for a cancer cell to survive. Further Reading

: At the energies used in treatment, photons (X-rays) typically interact via Compton scattering , where they bounce off electrons and transfer energy to them. Direct vs. Indirect Ionization : Direct : The radiation beam itself breaks DNA strands. Basic Radiotherapy Physics and Biology

Not all radiation is created equal. The describes how much energy a particle deposits as it travels through tissue: : These create dense "tracks" of ionization, causing

: Cells are most sensitive to radiation during certain phases of the cell cycle (like mitosis). Fractionating treatment (giving it in small daily doses) allows surviving cancer cells to move into these sensitive phases. Indirect Ionization : Direct : The radiation beam

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

: 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

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