Using radioactive drugs to see inside your body - Pedro Brugarolas

Summary

This video explains the process behind PET scans, focusing on the use of FDG, a radioactive glucose, to detect conditions like cancer and Alzheimer’s disease. It details how a cyclotron accelerates particles to create fluorine-18, which is then attached to molecules to form radiotracers. The video also covers how PET scans use radiation to create detailed 3D images of tracer distribution in the body. Though the radiation involved is low, PET scans are vital in diagnosing diseases and improving treatment strategies. The technology is also advancing to explore new applications for medical diagnostics.

Takeaways

• 😀 FDG, a radioactive glucose, is used in PET scans to help diagnose diseases like cancer.
• 😀 FDG is injected into the patient and circulates through the body, highlighting areas with high cancer cell activity.
• 😀 PET tracers like FDG are produced in a cyclotron, a particle accelerator that generates radioactive isotopes.
• 😀 The cyclotron accelerates protons to high speeds and uses them to transform oxygen-18 into fluorine-18.
• 😀 Fluorine-18 is radioactive and can be detected by PET scans, but it has a short half-life of about two hours.
• 😀 Radiochemists use fluorine-18 to create radiotracers by attaching it to various molecules depending on the condition being observed.
• 😀 FDG is commonly used for detecting cancer, infections, and brain function changes in diseases like dementia.
• 😀 PET scans detect radiation emitted by tracers, which collide with electrons to create high-energy photons that map the tracer's distribution.
• 😀 PET scans can identify cancer spread earlier than other imaging methods and help diagnose Alzheimer's by detecting amyloid buildup.
• 😀 PET scan radiation is minimal and safe, equivalent to exposure from natural sources over two to three years or a few transatlantic flights.
• 😀 Despite the radiation, many patients consider the benefits of PET scans for diagnosing and treating illnesses to outweigh the risks.

Q & A

What is FDG, and how is it used in medical diagnostics?

FDG (fluorodeoxyglucose) is a radioactive form of glucose used in medical diagnostics, particularly in PET (positron emission tomography) scans. It helps detect cancer, infections, and brain disorders by highlighting areas where glucose is consumed more rapidly, which can indicate abnormal cell activity.

How does the FDG tracer work in the body?

Once injected into the body, FDG circulates through the bloodstream and is absorbed by tissues, especially cancer cells. These cells tend to consume glucose at a higher rate, which makes FDG accumulate in areas of the body where there is disease, allowing PET scanners to detect the presence of tumors or infections.

What role does the particle accelerator, or cyclotron, play in creating FDG?

The cyclotron accelerates protons using electromagnetic fields until they reach high speeds. These protons then collide with oxygen-18 atoms, creating fluorine-18, a radioactive isotope that is incorporated into FDG, making it detectable in PET scans.

What is the significance of the radioactive decay of fluorine-18 in the context of PET scans?

Fluorine-18 decays quickly, with half of it disappearing in under two hours. This short half-life means that FDG must be used soon after it is produced, which is why the timing of the scan is critical in ensuring accurate results.

How is FDG chemically prepared for use in PET scans?

FDG is prepared by attaching fluorine-18 to a glucose molecule through a series of chemical reactions. This creates a radiolabeled glucose analog that can be injected into the body for imaging purposes.

Why is FDG commonly used in PET scans?

FDG is commonly used because it mimics glucose, which cells consume for energy. The uptake of FDG in cells can indicate areas of abnormal activity, such as cancerous growths or infections, making it a useful tracer for a variety of medical conditions.

What happens to the FDG once it is injected into the body?

After injection, FDG travels through the circulatory system and accumulates in tissues that require high amounts of glucose, such as cancer cells, brain cells, or areas of infection. This accumulation makes it visible to the PET scanner.

How do PET scanners detect the location of FDG in the body?

PET scanners detect the radiation emitted by the FDG tracer. When the fluorine-18 isotope decays, it releases positrons that collide with electrons, producing high-energy photons. These photons are detected by the scanner, creating a 3D image of the tracer's distribution in the body.

What makes PET scans valuable for diagnosing cancer and Alzheimer’s disease?

PET scans are valuable for diagnosing cancer because they can detect tumors before other imaging methods, even at early stages. For Alzheimer’s disease, PET scans can identify amyloid plaques, the hallmark protein deposits associated with the disease, which could not be confirmed otherwise without an autopsy.

Are PET scans safe, given their use of radioactive materials?

While no amount of ionizing radiation is completely safe, the radiation exposure from a PET scan is relatively low. The exposure from a single scan is comparable to several years of natural background radiation, making it generally safe for most patients when used judiciously for diagnosis.