Which scintillators are the usual choice for PET?

Which scintillators are the usual choice for PET?

However the scintillator of choice for PET cameras using block-detectors has been Bismuth germanate (BGO), which has a high effective Z, is not hygroscopic and does not have long-lived secondary scintillation components.

What are scintillators used for?

Scintillators are materials that are able to convert high energy radiation such as X or gamma-rays to a near visible or visible light. They are widely used as detectors in medical diagnostics, high energy physics and geophysical exploration (ref. Knoll).

What nuclides are used in positron emission tomography?

Most clinical PET studies use the nuclide 18F, which has to be produced using a cyclotron. The half-life of 18F is 110 min, long enough to allow transport over extended distances, and a number of cyclotrons supply 18F in the form of fluorodeoxyglucose.

Which detectors are used in PET imaging?

In most PET scanners today, scintillation detectors are used as detection elements. They couple inorganic scintillation crystals that emit visible or near ultraviolet light after interaction with an incident high-energy (511 keV) photon, to photo detectors that detect and measure the scintillation photons.

How do NaI scintillators work?

NaI(Tl) detectors The thallium-activated sodium iodide detector, or NaI(Tl) detector, responds to the gamma ray by producing a small flash of light, or a scintillation. The scintillation occurs when scintillator electrons, excited by the energy of the photon, return to their ground state.

What type of crystal is used in PET scanner?

inorganic scintillator crystals
In PET, inorganic scintillator crystals are used to record -y-rays produced by the annihilation of positrons emitted by injected tracers. The ultimate performanceof the camera is strongly tied to boththe physicaland scintillationpropertiesofthe crystals.

Why are scintillators doped?

The doping of the NaI crystal with thallium improves the scintillation efficiency by improving the light emission due to the improved recombination by light emission of electrons and holes at the dopant site.

What radiotracers are used in PET scans?

The radioisotopes used in PET to label tracers are 11C, 13N, 150, and 18F (carbon, nitrogen, oxygen and 18F used as a substitute for hydrogen). These radioactive forms of natural elements will pass through your body and be detected by the scanner.

What are PET tracers?

A PET radiotracer (also known as PET tracer) is a positron-emitting radiopharmaceutical used in positron emission tomography (PET). Each tracer consists of a positron-emitting isotope (radioactive tag) bound to an organic ligand (targeting agent).

How are positrons detected?

PET works by using a scanning device (a machine with a large hole at its center) to detect photons (subatomic particles) emitted by a radionuclide in the organ or tissue being examined.

What is a PET detector?

PET scanners detect the location of positron-emitting probes in vivo and produce a three-dimensional (3D) image (reviewed in Phelps, 2000). As the probe decays, positrons from the radionuclide annihilate with an electron in nearby tissue and emit two antiparallel 511 keV high-energy photons.

What is scintillator crystal?

A scintillation crystal absorbs gamma photons by one or more collision processes and converts some of their energy into visible light and ultraviolet (UV) photons. This is done through a process know as scintillation. In a sense, the crystal acts as a wavelength shifter.

Are collimators used in PET?

2. There are no collimators in front of the PET detectors; therefore the efficiency of PET is much higher than that of single-photon emission computed tomography (SPECT).

What are organic and inorganic scintillators?

In general, organic scintillators have fast decay times (typically ~10-8 sec), while inorganic crystals are usually far slower (~10-6 sec), although some also have fast components in their response.

Why is fluorine-18 used in PET scans?

Fluorine-18 is one of the several isotopes of fluorine that is routinely used in radiolabeling of biomolecules for PET; because of its positron emitting property and favorable half-life of 109.8 min.

Why do we use radiotracers?

Radioactive tracers are widely used to diagnose industrial reactors, for instance by measuring the flow rate of liquids, gases and solids. A radioactive tracer is a chemical compound in which one or more atoms have been replaced by a radioisotope.

Why is fluorodeoxyglucose used in PET scans?

For example, in PET scans of the brain, a radioactive atom is applied to glucose (blood sugar) to create a radionuclide called fluorodeoxyglucose (FDG), because the brain uses glucose for its metabolism.

What is the process of a PET scan?

During a positron emission tomography (PET) scan, you lie on a narrow table that slides into a doughnut-shaped hole. The scanner takes about 30 minutes to produce detailed images of metabolic activity in your tissues and organs.