Radiation therapy, a potent weapon in the fight against cancer, harnesses beams of high intense energy—typically X-rays or photon, employed—to combat malignant cells. When we speak of “Radiation Therapy,” we primarily refer to external beam radiation therapy. In this method, the body remains untouched as high-energy beams are directed from an external apparatus, precisely targeting tumour tissue. The primary mechanism involves damaging cells by disrupting their genetic materials, which regulate cellular growth and division. An essential aspect of this therapy is that it not only impact on cancerous cells but also on healthy tissue. The objective, however, is to minimize harm to healthy cells while killing the malignant cells. Normal cells often possess capability to repair the damage inflicted by radiation. The crux of radiation therapy lies in its delicate balance: seeking to obliterate cancer cells while sparing the least possible harm to the body’s healthy tissues.