Using radioactive drugs to see inside your body - Pedro Brugarolas

TED-Ed
19 Mar 201904:46
EducationalLearning
32 Likes 10 Comments

TLDRThe video script describes the use of FDG, a radioactive form of glucose, in PET (positron emission tomography) scans for medical diagnostics. The FDG is produced in a cyclotron, which accelerates protons to collide with oxygen-18, creating fluorine-18. This isotope is then chemically attached to glucose to form FDG, which is injected into patients. Cancer cells, being highly metabolic, absorb more FDG, acting as a signal for the PET scanner. The scanner detects the radiation emitted by the decaying fluorine-18, creating a 3D map of its distribution in the body. This technology is crucial for early cancer detection and diagnosing conditions like Alzheimer's. Despite concerns over radiation, the amount received during a PET scan is considered low and comparable to natural background exposure or that of a pilot flying transatlantically. The benefits of accurate diagnosis and treatment often outweigh the minimal risks.

Takeaways
  • 💉 The syringe contains FDG, a radioactive form of glucose used in PET scans to detect cancer.
  • 🏥 The PET scan process involves injecting the patient with FDG, which, if a tumor is present, will be absorbed by cancerous cells.
  • 🔬 The production of FDG starts in a cyclotron, which accelerates protons to create fluorine-18, a radioactive isotope.
  • ⏳ Fluorine-18 has a short half-life, which means scans must be conducted quickly after its production.
  • 🧪 Radiochemists can attach fluorine-18 to various molecules to create radiotracers for different diagnostic purposes.
  • 📈 FDG is commonly used because cancer cells' high glucose consumption can indicate their presence.
  • 🚀 The tracer circulates in the body and targets specific areas, such as proteins in the brain or cancer cells.
  • 🕰️ After a few minutes, the tracer accumulates at the target site, and excess tracer clears from the body.
  • 🧠 PET scanners detect the radiation emitted by the decaying isotopes, which collide with electrons and produce detectable photons.
  • 📊 The scanner's software creates a 3D map of the tracer distribution, allowing doctors to visualize the target area.
  • 🛡️ PET scans are considered safe, with radiation exposure comparable to natural background levels or that of a pilot's cosmic radiation exposure.
  • 🔬 Researchers are continually developing new tracers to expand the diagnostic capabilities of PET scans.
Q & A

  • What is FDG and why is it used in PET scans?

    -FDG stands for Fluorodeoxyglucose, a radioactive form of glucose. It is used in PET (Positron Emission Tomography) scans because cancer cells, which are more metabolically active, take up a significant portion of FDG, which then acts as a beacon for the scanner to detect tumors.

  • How is FDG produced?

    -FDG is produced in a particle accelerator known as a cyclotron. Charged particles like protons are accelerated and then collide with a target containing water with a heavy isotope of oxygen, oxygen-18. This collision results in the production of fluorine-18, which is used to make FDG.

  • What happens to fluorine-18 over time due to radioactive decay?

    -Fluorine-18 is a radioactive isotope that decays over time. In a little under two hours, about half of the fluorine-18 will have decayed, which is why there is a time-sensitive aspect to performing PET scans after its production.

  • How are radiotracers created and what is their purpose?

    -Radiotracers are created by radiochemists who use chemical reactions to attach radioactive fluorine to different molecules. The identity of the tracer depends on what the doctors want to observe, such as glucose consumption to signal cancer, an infection, or brain function in dementia.

  • How does a PET scanner detect the presence of FDG in the body?

    -A PET scanner detects the radiation emitted by the isotopes used in PET, which decay by positron emission. Positrons collide with electrons, resulting in a nuclear reaction that converts the mass of the two particles into two high-energy photons, which are then detected by the scanner to create a 3D map of the tracer’s distribution.

  • What are the potential applications of PET scans?

    -PET scans are used to detect the spread of cancer, diagnose Alzheimer’s disease by visualizing amyloid protein buildup, and are being researched for the development of new tracers to expand their diagnostic capabilities.

  • Is there a safety concern regarding the radiation exposure from PET scans?

    -While no amount of ionizing radiation is completely safe, the radiation exposure from a PET scan is relatively low. It is comparable to the natural background radiation exposure one might receive over two to three years or the cosmic radiation exposure a pilot would accumulate after 20 to 30 transatlantic flights.

  • How does the PET scan help in the early detection of cancer?

    -PET scans can detect the spread of cancer before it is visible with other imaging techniques. The high metabolic activity of cancer cells leads to increased uptake of FDG, which can be visualized by the PET scanner, allowing for earlier detection and treatment planning.

  • What is the role of the circulatory system in the process of a PET scan?

    -The circulatory system is crucial as the radiolabeled tracer, once injected into the body, travels through it and is taken up by its target, such as cancer cells or proteins in the brain. This targeted uptake allows the PET scanner to detect the tracer and create an image of the area of interest.

  • How do researchers contribute to the advancement of PET scans?

    -Researchers are actively working on developing new tracers to enhance the range of conditions that can be diagnosed with PET scans. Their work can lead to improved diagnostic accuracy and the ability to detect a broader range of diseases.

  • What is the significance of the PET scan in diagnosing Alzheimer’s disease?

    -PET scans are revolutionary in diagnosing Alzheimer’s disease as they allow doctors to visualize the buildup of amyloid proteins in the brain, a characteristic feature of the disease. This is particularly important as this buildup could not be confirmed without an autopsy prior to the use of PET scans.

  • How do the photons generated in the PET scan process help in creating a 3D map of the tracer’s distribution?

    -The photons generated from the nuclear reaction between positrons and electrons are detected by an array of paired radiation detectors in the PET scanner. The scanner’s software uses the data from these detectors to estimate the location of the collision within the body and constructs a 3D map of where the tracer has been distributed.

Outlines
00:00
💉 Introduction to FDG and PET Scanning

The video script begins with an introduction to a syringe filled with FDG, a radioactive form of glucose used in PET (positron emission tomography) scans to detect cancer. The FDG is injected into the patient and circulates through the body, where cancer cells, if present, absorb it. The production of FDG involves a cyclotron, which accelerates protons to collide with oxygen-18, creating fluorine-18. This isotope decays and can be attached to various molecules to form radiotracers, with FDG being a common one that helps identify cancer, infections, or dementia by monitoring glucose consumption rates. The tracer's journey through the body, its detection by a PET scanner, and the creation of a 3D map of its distribution are also explained. The script addresses the safety of PET scans, comparing the radiation exposure to natural and occupational sources, and concludes with the acceptance of these risks for diagnostic benefits.

Mindmap
Keywords
💡FDG (Fluorodeoxyglucose)
FDG, or Fluorodeoxyglucose, is a radioactive form of glucose used in PET scans to detect cancer. It is defined as a radiotracer that is taken up by cancer cells at a higher rate than normal cells due to their increased metabolic activity. In the video, FDG is injected into a patient and circulates through the body, where it acts as a beacon for the PET scanner if a tumor is present.
💡PET Scanner
A PET, or positron emission tomography, scanner is a medical imaging device that produces a three-dimensional image of functional processes within the body. It is used to detect diseases by capturing the radiation emitted by radiotracers like FDG. The scanner's software analyzes the data from radiation detectors to estimate where the tracer is located, creating a 3D map of its distribution within the body.
💡Cancer Cells
Cancer cells are abnormal cells that divide uncontrollably and can invade nearby tissues or spread to other parts of the body. They are a key focus of the video as the uptake of FDG by these cells indicates the presence of cancer. The PET scanner can detect these cells by identifying areas where FDG accumulates significantly.
💡Cyclotron
A cyclotron is a type of particle accelerator that is used to create radiotracers like FDG. It propels charged particles, such as protons, along a spiraling path using electromagnetic fields until they reach high speeds. The cyclotron is essential for producing the radioactive isotopes needed for PET scans, as it generates fluorine-18 by slamming protons into oxygen-18 atoms.
💡Radiotracer
A radiotracer is a radioactive compound that can be detected by medical imaging devices. In the context of the video, radiotracers like FDG are attached to different molecules to create specific diagnostic tools. They are used to observe various medical conditions, including cancer, by targeting and accumulating in specific areas of the body.
💡Radioactive Decay
Radioactive decay is the process by which an unstable atomic nucleus loses energy by emitting radiation. In the video, it is mentioned that fluorine-18 undergoes radioactive decay, with about half of it decaying in under two hours. This decay is crucial for PET scans as it allows the tracer to be detected and also limits the patient's exposure to radiation.
💡Positron Emission
Positron emission is a type of radioactive decay where a proton-rich nucleus emits a positron, a particle similar to an electron but with a positive charge. When a positron meets an electron, they annihilate each other, producing two gamma rays that are detected by the PET scanner. This process is central to how PET scans work, as it allows for the visualization of the tracer's location in the body.
💡Isotopes
Isotopes are variants of a particular chemical element that have the same number of protons but different numbers of neutrons. In the video, fluorine-18 is an isotope that is used in PET scans. The production of this isotope through the cyclotron and its subsequent decay is a key part of the diagnostic process.
💡Radiation Detectors
Radiation detectors are devices that detect and measure ionizing radiation, such as gamma rays emitted by radiotracers. In the PET scanner, an array of paired radiation detectors line the walls of the scanner and capture the gamma rays resulting from positron-electron annihilation. These detectors are essential for creating the 3D map of the tracer's distribution within the body.
💡Alzheimer's Disease
Alzheimer's disease is a progressive neurodegenerative disorder that causes memory loss and cognitive decline. The video mentions that PET scans are revolutionizing the diagnosis of Alzheimer's by allowing doctors to visualize the buildup of amyloid proteins in the brain, which are indicative of the disease and were previously difficult to confirm without an autopsy.
💡Ionizing Radiation
Ionizing radiation is a form of radiation that has enough energy to ionize atoms or molecules, causing them to become electrically charged. It is used in medical imaging but also carries risks due to its ability to damage biological tissues. The video discusses the safety of PET scans, noting that the amount of ionizing radiation received during a scan is relatively low and comparable to natural background radiation or that received by pilots from cosmic radiation.
Highlights

This syringe contains a radioactive form of glucose known as FDG, which is used to test for cancer using a PET scanner.

Cancer cells within a tumor take up a significant portion of the FDG, acting as a beacon for the scanner.

PET tracers like FDG are among the most remarkable tools in medical diagnostics.

FDG is produced in a particle accelerator called a cyclotron, which is often housed in a hospital bunker.

The cyclotron uses electromagnetic fields to accelerate protons to high speeds, which then collide with oxygen-18 to produce the radioactive isotope fluorine-18.

Fluorine-18 decays in about 2 hours, so it needs to be used quickly for PET scans.

Radiochemists attach the radioactive fluorine to different molecules to create radiotracers for observing specific medical conditions.

FDG is a common tracer because it can signal the presence of cancer, infection, or brain function issues like dementia based on glucose consumption rates.

The radiolabeled tracer circulates in the body and gets taken up by its target, like cancer cells or brain proteins.

Within minutes, the tracer accumulates at the target site while the rest clears from circulation, allowing doctors to visualize it using a PET scanner.

The radiation emitted by the isotopes in the tracer enables PET scans by causing positron-electron collisions that produce detectable photons.

The scanner's software uses paired radiation detectors to estimate the location of the tracer and create a 3D map of its distribution in the body.

PET scans can detect cancer spread and diagnose Alzheimer's by visualizing amyloid protein buildup, often before other imaging methods.

Researchers are actively developing new tracers to expand the capabilities of PET scans.

The radiation exposure from a PET scan is relatively low, comparable to 2-3 years of natural background radiation or a pilot's cosmic radiation exposure from 20-30 transatlantic flights.

Most patients find the risks of PET scans acceptable for the potential benefits in diagnosing and treating their illnesses.

Transcripts

Browse More Related Video

How X-rays see through your skin - Ge Wang

I Ignored the Signs - Jason | Stage 4 Colorectal Cancer | The Patient Story

Applications (Contd.)

Oral Cancer - causes, symptoms, diagnosis, treatment, pathology

A Brief Introduction to Alpha, Beta and Gamma Radiation

34. Radiation Hormesis

Rate This

5.0 / 5 (0 votes)

Thanks for rating:

Related Tags
Medical DiagnosticsPET ScansCancer DetectionFluorine-18CyclotronRadiochemistryPositron EmissionDementia DiagnosisInfection TrackingRadiation SafetyHealthcare Technology