Purpose:This presentation aims to educate surgeons on radiotherapy principles and their application in creating effective treatment protocols and describes recent technological advancements and subsequent improved outcomes. Background: Radiotherapy, a mainstay in cancer treatment since the late 19th century, involves using subatomic particles or X-rays to target neoplastic diseases. Approximately half of all cancer patients undergo radiation therapy, which can be a primary treatment, combined with chemotherapy, or supplementary to surgery. Linear accelerators direct electron jets to a target, producing ionizing photons. Ionizing radiation causes cell death by disrupting DNA during cell division, affecting rapidly dividing cells like tumour cells – but also native tissues such as gastrointestinal mucosa, resulting in adverse effects. Tumour cells are more vulnerable to injury due to their impaired DNA repair mechanisms. Fractionated radiotherapy, where treatment is divided over days to weeks, exploits this, allowing normal cells to recover between sessions while tumour cells cannot. This approach also enhances oxygenation within tumours as peripheral cells die, stimulating division in core cells to enable targeted destruction. Technological advancements such as IMRT have enabled precision targeting of tumour cells, achieving equivocal local control rates whilst minimising collateral damage. Conclusions:Radiotherapy is a core element of surgical oncology, yet surgeons often lack comprehensive knowledge. Bridging this knowledge gap is essential for the effective implementation of treatment protocols and improving patient outcomes. Up-to-date understanding of technological advancements enables effective patient communication about prognosis and risk.