In medical terminology, how is "radiotherapy" defined?

Radiotherapy is defined as the application of ionizing radiation to damage the DNA of cancer cells, which is essential in the treatment of various types of cancer. This method exploits the principle that cancer cells are more sensitive to radiation than normal cells, allowing for targeted treatment that can shrink tumors and potentially eradicate cancerous growths. The ionizing radiation disrupts the cellular structure, specifically targeting and damaging the DNA, which impairs the cancer cells' ability to proliferate and survive.

Other techniques listed, such as the use of high-frequency sound waves or non-ionizing radiation, focus on different therapeutic or diagnostic modalities and do not involve the direct destruction of cancerous tissue through ionizing radiation. The use of lasers in medical procedures also pertains to a different methodology that does not align with the fundamental definition of radiotherapy, which is distinctly linked to the targeting and treating of tumors through the direct effects of ionizing radiation.