How do PET scans work to detect things such as cancer?

In this video, I discuss Positron Emission Tomography.
In particular, I refer to the source of the positron, its annihilation and how the resultant gamma rays are collected. I also briefly discuss its diagnostic benefits.

See more Medical imaging techniques here -

LIKE and SHARE with your peers. And please add a COMMENT to let me know I have helped you.

OR

Physics High is committed to producing content that teaches physics concepts at a level a high schooler can understand.

👥 Social
---------------------------------------------------------
Follow me on
facebook: @physicshigh
twitter: @physicshigh
Instagram: @physicshigh

#physicshigh #highschoolphysicsexplained #medicalphysics

[emajossch]

It’s mind boggling how someone theorized how this could all work, and how someone engineered it to actually work as well. Stunning.

This is slightly off topic, but this is one of those things that really highlights how insanely developed we have become over the last century and a half. The fact we went from just barely figuring out how to build an automobile to theorizing and engineering something like this in such a relatively short amount of time is outrageous.

[PhysicssimplifiedbySunilBalani]

Very comprehensive explaination ..only thing the 180 degree angle between photons is consequence of conservation of momentum not conservation of energy .Masses of positron and electron anihilate and because the momentum must be conserved that is the reason instead of a single photons we have two photons moving anti phase.

[그리너리초이]

I have watched endless scientific videos having explanations but most of them were hard to understand.. that I ended up searching another videos to understand them... but this video!!! clears out all the complexity!!! thank you for providing me with such a clear explanation! :)

[NONFamers]

Back in the late 80s I worked for a Danish company producing PET- and SPECT-scanners. This little recap on how the PET-scanner works brought back many fond memories. Thanks for sharing!

[swatibhargava]

such a great video!! thank you sooo much!! this is the best explanation I found after looking at many resources and even better than what I learnt in my class! Super thanks for your work! Also looking to understand SPECT, I hope I can another video of yours explaining SPECT.

[colinehagnier]

Hey! Student from Cognitive Neuroscience! Very useful! Thanks a lot :) way more fast and interesting way to learn than good old books. You made the subject passionating! :D

[michaelporter]

Updated to correct unfinished thought:
Your explanation of the intensity of the gamma bursts detected (being 180° from one another) in one direction having to travel through more tissue than the bursts in the opposite direction as the way to locate where the bursts are originating, does not take into account the different distances traveled for each photon (of a particular photon pair) from the point of annihilation to the detector ring, nor the angles of incidence of each photon (of that photon pair) to the tangents of the detector ring at the points of detection: obviously if the annihilation occurrence is not dead center of the detector ring (circle), then either the resulting distances traveled by each photon (of that photon pair) to the detector ring will be different, or the angles of incidence of each photon (of that photon pair) to the tangents of the detector ring at the points of detection will not be 90°, or both. Re: your explanation from about 6:48 to about 10:36. Therefore, I submit that determining the locations from where the gamma bursts are originating is more a function of the values of their different distances from the detector ring, their angles of incidence to the tangents at the points of detection on the detector ring, or both. For any photon pair, knowing the difference in distance each photon has to travel to the detector ring, the diameter of the detector ring, and the angle of incidence to the tangents of the detector ring at the points of detection (angle will be the same [mirror-imaged] for both photons as their paths of travel are 180° in opposite directions to the detector ring: combined paths of both photons can be represented as a chord on a circle) is what is needed to locate where the gamma bursts are originating. The other information is known: speed of light, wavelength of photon and subsequent properties, mapping instrumentation, etc.

[haithamfarok]

Great explanation of the PET scanner with good graphics and simple terms. Many thanks.

[giorgos]

Excellent and simple explanation of the PET physics. Just one comment, though: what you say around 9.25 that the scanner is able to determine the source of the annihilation by calculating the energy difference between the two coincidence photons is purely wrong - for many reasons. Most importantly, the LSO or LYSO detectors do not have sufficient energy resolution to determine the location of the annihilation within a few mm - as you suggest. If that was possible, you wouldn't really require a ring of detectors, because you could just simply histogram the coincidence events into an image. However, this is NOT possible and tomographic information is necessary (i.e. events around the object) to resolve the location of the annihilation. Having said that, most clinical scanners nowadays can measure the arrival time of the coincidence photons with high accuracy (in the order of pico-seconds) and as such they can narrow down the location of the annihilation within a few millimeters (the location is actually a Gaussian distribution). This is called Time of Flight and although it can substantially improve the signal to noise of the reconstructed images, you still require sufficient tomographic information around the object. There were a couple other minor inaccuracies in your explanation, but most of it was really good and simple! Well done!

[pret]

Thank you for the video, this is definitely going to help me in the presentation today :-) !!

[faheemmohd]

Thank you for all the explanations. Helps me a lot. Wish u all the best in future....

[diana-stefaniasima]

Thank you so much for your explanations! Really clear and very useful !

[mrpcuthbertson]

Excellent teaching aid - thanks very much!

[thangnguyenquang]

This sure gonna helps me a lot in my presentation today. Thanks

[dinaabdelaziz]

Great video and explains really in a simple way I just had a pet scan you really explained everything that happened to me thank you

[yumnabarhamji]

wow this is the most interesting thing ever and thankyou for explaining it so so well

[theontaylorshand]

you helped me pass grade nine thank you so much-

[samreenfarooq]

I wish I could hit that like button twice !!!👍👍TYSM

[kkhamees]

Great explanation. You are very good teacher.

[garethjackson]

Brilliant explanation. I have unfortunately had 2 of these scans in the last 6 months, so understanding what is happening is excellent. Quick question? How sensitive is this though? Will a scan only pick up a glucose hungry tumour? Or could it potentially find just initial stages on cancer cells etc? Thank you for a very clever video.