What is the difference between external and internal radiotherapy?

The distinction between external and internal radiotherapy lies primarily in the source and delivery of radiation. External radiotherapy, as the name suggests, utilizes radiation generated from outside the body. This method typically involves a machine that directs high-energy beams, such as X-rays or gamma rays, at the tumor from different angles to maximize impact on cancer cells while sparing surrounding healthy tissue.

In contrast, internal radiotherapy, often referred to as brachytherapy, involves the use of radioactive sources that are implanted directly within or very close to the tumor site. This localized delivery of radiation allows for a higher dose to be administered directly to the cancerous tissues while minimizing exposure to adjacent healthy structures.

Understanding this difference is crucial in radiology and oncology, as it impacts treatment planning and patient management. Options that suggest internal radiotherapy is only for diagnostics or that both types use external sources misunderstand their applications and methodologies.