TedEd: Performing brain surgery without a scalpel

Hyunsoo Joshua No

Thousands of people each year undergo brain surgery without an operation. A new procedure called stereotactic radiosurgery works by using beams of radiation to wear away malignant cells. The procedure involves a series of CT-scans that determine the location and size of the tumor. For some patients, an additional MRI may be needed. CT-scans also calculate the Hounsfield units of various parts of the brain, which shows the density of a material. This is important because this determines how radiation will spread through the brain. Radiosurgery uses multiple beams of radiation that converge on a tumor and destroy it. This is also helpful for doctors because they can change the angle and intensity of each beam to avoid surrounding brain structures. When the beams hit a cancer cell, they essentially cut their DNA into pieces, which causes the malignant cell to break down and eventually die. The radiation also breaks down molecules in the brain and produce unstable products called free radicals that create a poisonous environment for the cells. The immune system then cleans up the dead cells and produces scar tissue. However, there are multiple restrictions on radiosurgery. It is generally used in very small areas, and because radiation adds up in the body, recurring treatments are risky. Still, the benefits often outweigh the risks. Its success rate is as high as normal surgery for many diseases, and it requires little to no recovery time or pain.