Con ten ts
01 Physics in nuclear medicine
02 Tracer production
03 Preclinical evaluation of PET tracers
04 You’ve designed a nice new tracer, now what? The first in man study - neuro
05 Advanced molecular PET imaging in oncology
06 Summary literature
07 CT physics
08 CT & dual energy CT
09 CT in movement sciences
10 CT in oncology
11 CT in cardiology
12 Imaging in Neurology
13 MRI – part 1
14 MRI – Part 2
15 MRI – Part 3
16 MRI – Part 4
17 MRI – Part 5
, lecture 01
Physics in nu clear m edicine
Imaging Principles
GOAL -> background on how we get to PET images. Have an idea on where the PET
images comes from.
Basic Atomic and Nuclear Physics
- Nucleus Composition: Protons (+) and neutrons (0) make up the nucleus.
Electrons are in the K, L, M, and N shell around the nucleus. Unstable
(radioactive) elements have too much energy and aim to return to a ground
state, releasing this energy in the process.
- Radioactive Decay: This process can involve the emission of alpha particles (He),
beta particles (e-), or gamma rays (photons).
- Isotope Notation: A is mass number (number of protons+neutrons), Z is
atomic number (number of protons), and X is the element symbol.
Unit of Radioactivity
- Becquerel (Bq): The unit of radioactivity, defined as the number of
disintegrations per second.
Ionizing Radiation
- Definition: Radiation that has enough energy to cause damage to living tissue
DECAY OF RADIOACTIVITY!!!
Decay: the fraction of atoms that decays back to the ground state over time is
stable.
Applications in medical imaging
- Radiotracers: Radioactive isotopes are bound to biologically significant molecules
(e.g., glucose) to trace processes within the body.
- FDG PET Scans: Comprising 90% of nuclear medicine, these scans detect areas of
increased glucose consumption, providing sensitive monitoring of tumor
responses before changes are visible on MRI/CT.
Imaging Techniques
- PET (Positron Emission Tomography): Involves positron emission from unstable
isotopes. The patient becomes a source of photons after administration of a
radiotracer, which is scanned after a waiting period for distribution.
- SPECT (Single Photon Emission Computed Tomography): Utilizes collimation for
imaging and detects emitted gamma rays.
Interaction of Radiation with Matter
- Radiation Absorption: E.g. solid bone absorbs significant radiation; fractures allow
more photons to pass through, which can be observed on CT scans.
- Key Effects:
, o Photoelectric Effect: Photons are absorbed by an inner shell electron of an
atom, resulting in attenuation (=reduction of energy). All the photon energy
is transferred to the electron so that photon disappears.
o Compton Scattering: A photon collides with an electron in the matter, causing
the photon to lose energy and change direction, which complicates the
localization of the original photon path.
Detection of Radiation
- Scintillation Detectors: Convert ionizing radiation (gamma) into visible photons.
These photons are amplified into an electric current for detection using
photomultiplier tubes.
Improving Imaging Quality
- Strategies to Reduce Noise in PET:
o Lengthen scan duration.
o Increase radiotracer dosage (considering potential side effects).
Spatial Resolution
- = The minimum distance between two distinct points in an image that can be
clearly separated and identified as individual entities.
o PET has approximately 0.5cm spatial resolution, while SPECT has a resolution
of about 1 cm.
, lecture 02
Tr acer pr odu ction
Imaging Principles
Tracer Chemistry
A tracer is created by combining a biologically active molecule with a radionuclide
(radioactive isotope).
Frequently Used PET Radionuclides
The half-life of a nuclide determines its usability:
- Carbon-11: 20-minute half-life
o Advantages: Can easily replace carbon-12 (stable form present in many
processes).
o Disadvantages: Short half-life creates time pressure.
o Production: Bombard N14 with a proton, which makes an alpha particle go
out, to get C11.
- Fluorine-18: 110-minute half-life
o Advantages: Good balance between usability and decay time.
o Production: Bombard O18 with a proton, which makes a neutron particle go
out, to get F18.
- Zirconium-89: 78.4-hour half-life
o Useful for longer studies.
o Production: Bombard Y89 with a proton, which makes a neutron particle go
out, to get Zr89.
Radionuclide Production
Radionuclides are produced on-site using a cyclotron:
- Cyclotron operation:
o High-vacuum chamber accelerates charged particles using an electrical field.
H⁻ ions are accelerated to 18 MeV using a combination of electric and
magnetic fields. When an electrical field is applied between two poles,
the particle is accelerated. A magnetic field is placed perpendicular to the
electrical field, causing the charged particles to move in circular paths.
Each time the particle passes through the electrical field, it gains more
energy and accelerates further. This process continues until the charged
particle reaches a maximum energy of 18 MeV.
When the maximum energy is reached, carbon foil takes of electrons,
converting H⁻ to H⁺ (protons). This changes it direction, making it go out
of the accelerator.
Protons bombard the target material to make it radioactive.
- Target states:
o Zr-89: Solid state.
o C-11: Gas state.
o F-18: Liquid state.
Chemistry of C-11
- Advantages:
o Versatile chemistry options. You can make a lot of different types of tracers.
01 Physics in nuclear medicine
02 Tracer production
03 Preclinical evaluation of PET tracers
04 You’ve designed a nice new tracer, now what? The first in man study - neuro
05 Advanced molecular PET imaging in oncology
06 Summary literature
07 CT physics
08 CT & dual energy CT
09 CT in movement sciences
10 CT in oncology
11 CT in cardiology
12 Imaging in Neurology
13 MRI – part 1
14 MRI – Part 2
15 MRI – Part 3
16 MRI – Part 4
17 MRI – Part 5
, lecture 01
Physics in nu clear m edicine
Imaging Principles
GOAL -> background on how we get to PET images. Have an idea on where the PET
images comes from.
Basic Atomic and Nuclear Physics
- Nucleus Composition: Protons (+) and neutrons (0) make up the nucleus.
Electrons are in the K, L, M, and N shell around the nucleus. Unstable
(radioactive) elements have too much energy and aim to return to a ground
state, releasing this energy in the process.
- Radioactive Decay: This process can involve the emission of alpha particles (He),
beta particles (e-), or gamma rays (photons).
- Isotope Notation: A is mass number (number of protons+neutrons), Z is
atomic number (number of protons), and X is the element symbol.
Unit of Radioactivity
- Becquerel (Bq): The unit of radioactivity, defined as the number of
disintegrations per second.
Ionizing Radiation
- Definition: Radiation that has enough energy to cause damage to living tissue
DECAY OF RADIOACTIVITY!!!
Decay: the fraction of atoms that decays back to the ground state over time is
stable.
Applications in medical imaging
- Radiotracers: Radioactive isotopes are bound to biologically significant molecules
(e.g., glucose) to trace processes within the body.
- FDG PET Scans: Comprising 90% of nuclear medicine, these scans detect areas of
increased glucose consumption, providing sensitive monitoring of tumor
responses before changes are visible on MRI/CT.
Imaging Techniques
- PET (Positron Emission Tomography): Involves positron emission from unstable
isotopes. The patient becomes a source of photons after administration of a
radiotracer, which is scanned after a waiting period for distribution.
- SPECT (Single Photon Emission Computed Tomography): Utilizes collimation for
imaging and detects emitted gamma rays.
Interaction of Radiation with Matter
- Radiation Absorption: E.g. solid bone absorbs significant radiation; fractures allow
more photons to pass through, which can be observed on CT scans.
- Key Effects:
, o Photoelectric Effect: Photons are absorbed by an inner shell electron of an
atom, resulting in attenuation (=reduction of energy). All the photon energy
is transferred to the electron so that photon disappears.
o Compton Scattering: A photon collides with an electron in the matter, causing
the photon to lose energy and change direction, which complicates the
localization of the original photon path.
Detection of Radiation
- Scintillation Detectors: Convert ionizing radiation (gamma) into visible photons.
These photons are amplified into an electric current for detection using
photomultiplier tubes.
Improving Imaging Quality
- Strategies to Reduce Noise in PET:
o Lengthen scan duration.
o Increase radiotracer dosage (considering potential side effects).
Spatial Resolution
- = The minimum distance between two distinct points in an image that can be
clearly separated and identified as individual entities.
o PET has approximately 0.5cm spatial resolution, while SPECT has a resolution
of about 1 cm.
, lecture 02
Tr acer pr odu ction
Imaging Principles
Tracer Chemistry
A tracer is created by combining a biologically active molecule with a radionuclide
(radioactive isotope).
Frequently Used PET Radionuclides
The half-life of a nuclide determines its usability:
- Carbon-11: 20-minute half-life
o Advantages: Can easily replace carbon-12 (stable form present in many
processes).
o Disadvantages: Short half-life creates time pressure.
o Production: Bombard N14 with a proton, which makes an alpha particle go
out, to get C11.
- Fluorine-18: 110-minute half-life
o Advantages: Good balance between usability and decay time.
o Production: Bombard O18 with a proton, which makes a neutron particle go
out, to get F18.
- Zirconium-89: 78.4-hour half-life
o Useful for longer studies.
o Production: Bombard Y89 with a proton, which makes a neutron particle go
out, to get Zr89.
Radionuclide Production
Radionuclides are produced on-site using a cyclotron:
- Cyclotron operation:
o High-vacuum chamber accelerates charged particles using an electrical field.
H⁻ ions are accelerated to 18 MeV using a combination of electric and
magnetic fields. When an electrical field is applied between two poles,
the particle is accelerated. A magnetic field is placed perpendicular to the
electrical field, causing the charged particles to move in circular paths.
Each time the particle passes through the electrical field, it gains more
energy and accelerates further. This process continues until the charged
particle reaches a maximum energy of 18 MeV.
When the maximum energy is reached, carbon foil takes of electrons,
converting H⁻ to H⁺ (protons). This changes it direction, making it go out
of the accelerator.
Protons bombard the target material to make it radioactive.
- Target states:
o Zr-89: Solid state.
o C-11: Gas state.
o F-18: Liquid state.
Chemistry of C-11
- Advantages:
o Versatile chemistry options. You can make a lot of different types of tracers.
