Name: Why do hospitals have particle accelerators? - Pedro Brugarolas
Uploaded: 2020-03-25T10:46:02.000Z
Duration: 4 min 47 s
Description: Thousands of YouTube videos with English-Chinese subtitles! Now you can learn to understand native speakers, expand your vocabulary, and improve your pronunciation...

This syringe contains a radioactive form  of glucose known as FDG.

The doctor will soon inject its contents  into her patient’s arm,

whom she’s testing for cancer  using a PET scanner.

The FDG will quickly circulate  through his body.

cancer cells within it will take up a  significant portion of the FDG,

which will act as a beacon  for the scanner.

are among the most remarkable tools  in medical diagnostics,

and their life begins in  a particle accelerator,

The particle accelerator in question  is called a cyclotron,

and it’s often housed in a bunker  within hospitals.

It uses electromagnetic fields to propel  charged particles

like protons faster and faster  along a spiraling path.

When the protons reach  their maximum speed,

they shoot out onto a target that contains a few milliliters of a type of water

with a heavy form of oxygen  called oxygen-18.

When a proton slams into one of these  heavier oxygen atoms,

it kicks out another subatomic particle  called a neutron.

This impact turns oxygen-18  into fluorine-18,

a radioactive isotope that can be  detected on a PET scan.

about half the fluorine will be gone  due to radioactive decay,

so the clock is ticking  to get the scan done.

So how can fluorine-18 be  used to detect diseases?

Radiochemists at the hospital can use  a series of chemical reactions

to attach the radioactive fluorine  to different molecules,

The identity of the tracer depends on what doctors want to observe.

FDG is a common one because the rate at  which cells consume glucose

or the slowing brain function of dementia.

The FDG is now ready for  the patient’s scan.

When a radiolabeled tracer  enters the body,

it travels through the circulatory system  and gets taken up by its target—

whether that's a protein in the brain, cancer cells, or otherwise.

a significant amount of the tracer has  found its way to the target area

and the rest has cleared from circulation.

Now the doctors can see  their target using a PET,

or positron emission tomography, scanner.

The radiation that the tracer emits  is what makes this possible.

The isotopes used in PET decay  by positron emission.

Positrons are essentially electrons  with positive charge.

When emitted, a positron collides  with an electron

from another molecule in its surroundings.

in which the mass of the two particles is  converted into two high-energy photons,

of paired radiation detectors  in the scanner walls.

The software in the scanner  uses those detectors

to estimate where inside the body  the collision occurred

and create a 3D map of the  tracer’s distribution.

PET scans can detect the spread of cancer

before it can be spotted with  other types of imaging.

They’re also revolutionizing the diagnosis of Alzheimer’s disease

the telltale protein buildup that  otherwise couldn’t be confirmed

Meanwhile, researchers are actively  working to develop new tracers

and expand the possibilities of what  PET scans can be used for.

But with all this talk of radiation and nuclear reactions inside the body,

Even though no amount of ionizing  radiation is completely safe,

the amount of radiation the body receives during a PET scan is actually quite low.

One scan is comparable to what you’re  exposed to over two or three years

from natural radioactive sources,  like radon gas;

from cosmic radiation after  20 to 30 transatlantic flights.

Most patients feel that those risks  are acceptable

for the chance to diagnose  and treat their illnesses.

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Why do hospitals have particle accelerators? - Pedro Brugarolas

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