The basics of positron emission tomography

[klotza]

klotza submitted a new PF Insights post

The Basics of Positron Emission Tomography (PET)

Continue reading the Original PF Insights Post.

 

[Choppy]

Great summary!

 

[Greg Bernhardt]

Always love to read about medical physics! It's an important field!

 

[ZapperZ]

There are also other advances in physics beyond elementary particles that made this, and many other areas of medicine, possible. Note that there has to be a very good detector to detect the photons created. The area of detector and device physics is crucial here, because the process is only as good as what it can detect and display in the end. The sound coming from your hi-fi system is only as good as the speakers at the very end (or your headphones), no matter how much you spent on the rest of your sound system.

And interestingly enough, the drive to make better photodetectors comes out of basic, fundamental research. The need to have better detectors to detect the Cerenkov light made by neutrinos passing through water drives the technology to make better photodetectors, which in turn, trickles down to many other applications, including more efficient detectors for PET scans.

The moral of the story here is that, pick ANY medical device or procedure, and there is an extremely good chance that it came out of more than one area of physics, and that it benefited from the advances made not only in terms of physics knowledge, but also in terms of side-benefits of physics experiments.

Zz.

 

[tthomson]

I worked on PET scanners for a while, and the typical detectors consist of Bismuth Germinate crystals glued onto photomultiplier tubes. The Bismuth Germinate crystals are transparent, and convert the impinging gamma rays (511KeV) to blue light (Cerenkov), which is detected by the photomultiplier tube and amplified to give an electrical pulse.

These devices use Positronic Flourine as indictaced, but also Positronic Oxygen (half life 30 seconds) and other Positronic elements typically generated on-site using a low cost cyclotron.

 

[Greg Bernhardt]

Just left a presentation about brain imaging and they talked about PET. This researcher worked mainly on mapping memory in the brain. Seemed to prefer fMRI. Interesting stuff!

 

[Garlic]

I worked on PET scanners for a while, and the typical detectors consist of Bismuth Germinate crystals glued onto photomultiplier tubes. The Bismuth Germinate crystals are transparent, and convert the impinging gamma rays (511KeV) to blue light (Cerenkov), which is detected by the photomultiplier tube and amplified to give an electrical pulse.

These devices use Positronic Flourine as indictaced, but also Positronic Oxygen (half life 30 seconds) and other Positronic elements typically generated on-site using a low cost cyclotron.

This is really cool.

What does it have to with Cerenkov radiation? How can Cerenkov radiation be created with gamma rays?

 

[ZapperZ]

This is really cool.

What does it have to with Cerenkov radiation? How can Cerenkov radiation be created with gamma rays?

It's very difficult to detect gamma rays. One of its signature is that gamma rays tend to knock off electrons from atoms of the material, and these electrons are often so energetic, that it has a relativistic speed higher than the speed of light in that material. When this happens, you get Cerenkov radiation.

This is also the common technique to detect neutrinos. You don't detect neutrinos, you detect the after effect of its collision with the water molecule resulting in a relativistic electron having speed higher than light in water (or whatever medium that is being used). This also creates a Cerenkov radiation.

Thus, the similarities between the two means that advancement in neutrino detection has a DIRECT effect and application in the detection technology for PET scans.

Zz.

 

[berkeman]

(Note -- an off-topic sub-thread has been deleted)