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  • Every year, tens of thousands of people world-wide have brain surgery

  • without a single incision:

  • there's no scalpel, no operating table, and the patient loses no blood.

  • Instead, this procedure takes place in a shielded room

  • with a large machine that emits invisible beams of light

  • at a precise target inside the brain.

  • This treatment is called stereotactic radiosurgery,

  • and those light beams are beams of radiation:

  • their task is to destroy tumors by gradually scrubbing away malignant cells.

  • For patients, the process begins with a CT-scan,

  • a series of x-rays that produce a three-dimensional map of the head.

  • This reveals the precise location, size, and shape of the tumor within.

  • The CT-scans also help to calculate something called "Hounsfield Units,"

  • which show the densities of different tissues.

  • This offers information about how radiation

  • will propagate through the brain, to better optimize its effects.

  • Doctors might also use magnetic resonance imaging, or MRI's,

  • that produce finer images of soft tissue,

  • to assist in better outlining a tumor's shape and location.

  • Mapping its precise position and size is crucial

  • because of the high doses of radiation needed to treat tumors.

  • Radiosurgery depends on the use of multiple beams.

  • Individually, each delivers a low dose of radiation.

  • But, like several stage lights converging on the same point

  • to create a bright and inescapable spotlight, when combined,

  • the rays of radiation collectively produce enough power to destroy tumors.

  • In addition to enabling doctors to target tumors in the brain

  • while leaving the surrounding healthy tissue relatively unharmed,

  • the use of multiple beams also gives doctors flexibility.

  • They can optimize the best angles and routes through brain tissue

  • to reach the target and adjust the intensity within each beam

  • as necessary.

  • This helps spare critical structures within the brain.

  • But what exactly does this ingenious approach do to the tumors in question?

  • When several beams of radiation intersect to strike a mass of cancerous cells,

  • their combined force essentially shears the cells' DNA,

  • causing a breakdown in the cells' structure.

  • Over time, this process cascades into destroying the whole tumor.

  • Indirectly, the rays also damage the area immediately surrounding the DNA,

  • creating unstable particles called free radicals.

  • This generates a hazardous microenvironment

  • that's inhospitable to the tumor,

  • as well as some healthy cells in the immediate vicinity.

  • The risk of harming non-cancerous tissue is reduced

  • by keeping the radiation beam coverage

  • as close to the exact shape of the tumor as possible.

  • Once radiosurgery treatment has destroyed the tumor's cells,

  • the body's natural cleaning mechanism kicks in.

  • The immune system rapidly sweeps up the husks of dead cells

  • to flush them out of the body, while other cells transform into scar tissue.

  • Despite its innovations, radiosurgery isn't always the primary choice

  • for all brain cancer treatments.

  • For starters, it's typically reserved for smaller tumors.

  • Radiation also has a cumulative effect,

  • meaning that earlier doses can overlap with those delivered later on.

  • So patients with recurrent tumors

  • may have limitations with future radiosurgery treatments.

  • But these disadvantages weigh up against some much larger benefits.

  • For several types of brain tumors,

  • radiosurgery can be as successful as traditional brain surgery

  • at destroying cancerous cells.

  • In tumors called meningiomas, recurrence is found to be equal, or lower,

  • when the patient undergoes radiosurgery.

  • And compared to traditional surgery

  • often a painful experience with a long recovery period

  • radiosurgery is generally pain-free,

  • and often requires little to no recovery time.

  • Brain tumors aren't the only target for this type of treatment:

  • its concepts have been put to use on tumors of the lungs, liver, and pancreas.

  • Meanwhile, doctors are experimenting with using it to treat conditions

  • such as Parkinson's disease, epilepsy, and obsessive compulsive disorder.

  • The pain of a cancer diagnosis can be devastating,

  • but advancements in these non-invasive procedures

  • are paving a pathway for a more gentle cure.

Every year, tens of thousands of people world-wide have brain surgery

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B2 radiation brain tumor tissue surgery cancerous

Performing brain surgery without a scalpel - Hyunsoo Joshua No

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    林宜悉 posted on 2020/12/01
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