How is radiation therapy typically delivered in cancer treatment?

Radiation therapy is typically delivered either externally or internally, making this the most comprehensive and accurate description.

External beam radiation therapy, which is more commonly used, involves directing high-energy beams (like X-rays) from outside the body to target and destroy cancer cells. This method allows for precise targeting of tumors while minimizing damage to surrounding healthy tissue.

Internal radiation therapy, also known as brachytherapy, involves placing radioactive sources directly inside or very close to the tumor. This method delivers a higher dose of radiation directly to the cancerous area while limiting exposure to surrounding healthy tissue.

The other options presented do not capture the dual nature of radiation therapy. For example, the first option limits the method to only internal means, overlooking the prevalent external beam therapy. The second option incorrectly associates radiation therapy solely with chemotherapy, which are distinct treatment modalities. Lastly, stating that radiation is delivered solely by surgery is inaccurate, as surgery is a separate treatment approach that may or may not be used alongside radiation therapy, but does not involve the delivery of radiation itself.