Cara kerja Siklotron untuk produksi radiofarmaka di Kedokteran Nuklir| Nuclear Medicine #3

Summary

This video explains the function of cyclotrons in producing radionuclides, particularly for medical applications. It describes how cyclotrons accelerate charged particles, such as protons, through alternating electric fields and static magnetic fields to create high-energy particles that hit a target and produce radioisotopes. The video further explores the mechanism behind the circular path of particles, how they gain kinetic energy, and their eventual ejection toward a target. Radioisotopes produced, like F18, are essential for medical imaging, especially in PET scans. The video concludes by explaining how these isotopes are used in nuclear medicine for patient imaging and diagnosis.

Takeaways

• 😀 A cyclotron is a device used to produce radionuclides by shooting charged particles into a target nucleus at high speeds.
• 😀 Charged particles, such as protons or hydrogen ions, need to be accelerated to very high kinetic energy to penetrate the Coulomb barrier of the atomic nucleus.
• 😀 The cyclotron has two semicircular electrodes (A and B) connected to an alternating voltage, creating changing electric fields to accelerate particles.
• 😀 A static magnetic field is applied to the cyclotron, which forces the accelerated charged particles to follow a circular path.
• 😀 The principle of Lorentz force is used to guide charged particles in their circular trajectory, where the force is perpendicular to both the velocity of the particles and the magnetic field.
• 😀 The charged particles are created in the gap between the electrodes, where an ion source (like an electrical arc) generates positively charged particles (e.g., protons).
• 😀 The alternating electric field changes polarity at a high frequency (25-30 MHz), causing the charged particles to accelerate and continue their circular motion.
• 😀 As charged particles move through the gap between the electrodes, they gain more energy with each pass, increasing their speed and the radius of their circular path.
• 😀 When the particles reach a high speed, they are directed to a target using a deflector electrode, which changes polarity to guide them toward the exit window.
• 😀 The cyclotron produces radionuclides, which can decay through processes like positive beta decay or electron capture, making them useful in medical imaging techniques like PET scans.

Q & A

What is a cyclotron, and how does it work?

A cyclotron is a device used to produce radionuclides by accelerating charged particles (such as protons) to high speeds, causing them to interact with a target nucleus to produce radioactive isotopes. It uses an alternating electric field and a static magnetic field to accelerate particles in a circular path, increasing their kinetic energy until they hit a target.

Why is high kinetic energy important for the particles in a cyclotron?

High kinetic energy is essential because particles need enough energy to overcome the Coulomb barrier of the atomic nucleus. Without sufficient energy, the particles can't interact with the nucleus and will only be scattered.

What role do the electrodes play in the cyclotron?

The cyclotron has two electrodes, A and B, that create an alternating electric field. These electrodes accelerate charged particles by alternating their polarity at high frequencies, which continuously increases the particles' speed as they move in a circular path.

What is the function of the static magnetic field in the cyclotron?

The static magnetic field, applied perpendicular to the electric field, forces charged particles to move in a circular path due to the Lorentz force. The magnetic field is crucial for controlling the particle trajectory and ensuring continuous acceleration.

How does the Lorentz force affect the particle's movement?

The Lorentz force, which is determined using the right-hand rule, causes the charged particles to move in a curved trajectory. The direction of the force is perpendicular to both the velocity of the particles and the magnetic field, resulting in circular motion.

What happens when the charged particles reach the edge of the cyclotron's electrode?

When the charged particles reach the edge of the electrode, the polarity of the electric field changes, causing the particles to reverse direction and continue their circular motion. As they pass through the gap, they gain more energy and continue to accelerate.

How is the charged particle extracted from the cyclotron?

The charged particle is extracted from the cyclotron using a deflector electrode. This electrode applies an opposite charge to the particles, directing them to an exit window where they can hit a target to produce radionuclides.

What type of nuclear reactions typically occur in the cyclotron?

Cyclotrons primarily cause activation reactions, where charged particles (usually protons) interact with a target nucleus, leading to the production of radionuclides. These radionuclides often undergo beta decay or electron capture.

Why are the radionuclides produced in a cyclotron considered 'carrier-free'?

Radionuclides produced in a cyclotron are considered 'carrier-free' because they are created by adding protons to a target nucleus, which only changes the atomic number and not the isotopic composition. This results in pure isotopes without the need for a carrier.

What is the most commonly used radionuclide in nuclear medicine, and how is it produced?

The most commonly used radionuclide in nuclear medicine is F-18, which is produced in a cyclotron by bombarding oxygen-18 with protons. This reaction produces F-18, which has a half-life of 110 minutes and is used in positron emission tomography (PET) imaging.