Reviewing the Physical Principles, Technological Platforms, and Clinical Applications of External Beam Radiotherapy
External Beam Radiotherapy ($\text{EBRT}$) is a widely utilized non-invasive cancer treatment that employs medical linear accelerators ($\text{LINACs}$) to generate and deliver high-energy photons or electrons to a tumor site, aiming to induce lethal $\text{DNA}$ damage in cancer cells while meticulously sparing the surrounding organs and healthy tissues from unnecessary radiation exposure.
The success of $\text{EBRT}$ is dependent on the precise integration of advanced engineering, complex physics, and sophisticated treatment planning to define the optimal dose, beam angles, and total treatment duration, leveraging the differential radiosensitivity between malignant and normal cells.
Modern $\text{EBRT}$ techniques have dramatically increased precision and conformality. **Intensity-Modulated Radiation Therapy ($\text{IMRT}$)** and **Volumetric Modulated Arc Therapy ($\text{VMAT}$)** use computer-controlled multileaf collimators ($\text{MLCs}$) to dynamically shape the beam and vary the dose intensity across the tumor volume, allowing concave dose distributions that hug complex tumor shapes. **Image-Guided Radiation Therapy ($\text{IGRT}$)** is now standard, using daily imaging (e.g., Cone Beam…
