The main difference between SPECT and PET scans is the type of radiotracers used. While SPECT scans measure gamma rays, the decay of the radiotracers used with PET scans produce small particles called positrons. A positron is a particle with roughly the same mass as an electron but oppositely charged.
Table of Contents
What is the physics of a PET scan?
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 PET scans work a level physics?
In PET scanning: Positrons are emitted by the decay of the tracer. They travel a small distance and annihilate when they interact with electrons in the tissue. This annihilation produces a pair of gamma-ray photons which travel in opposite directions.
What is the principle of PET imaging?
The principle of positron emission tomography (PET) is that radiation emitted from a radiopharmaceutical injected intravenously into a patient is registered by external detectors positioned at different orientations.
Why does PET have low spatial resolution?
In order to reduce the number of electronics channels, most PET cameras have detectors that employ some form of optical multiplexing, where there are more scintillation crystals than photodetector elements. This decoding is often imperfect, which degrades the spatial resolution.
Do PET scans use gamma rays?
PET scans register the gamma rays emitted from positron-electron annihilation. These positrons are given off by a radioactive isotope during positron decay. The scan process starts with the patient being injected with some type of radioactive tracer that has been attached to some metabolized molecule, such as glucose.
What is the principle of SPECT?
Principle of SPECT Gamma-ray photons emitted from the internal distributed radiopharmaceutical penetrate through the animal’s or patient’s body and are detected by a single or a set of collimated radiation detectors.
How does a SPECT work?
How does a SPECT scan work? A radioactive tracer is injected into your bloodstream. Inside your body, the tracer produces a type of energy called gamma rays. A gamma camera picks up signals from the tracer, and a computer converts them into pictures of blood flow through your heart.
What makes PET and SPECT so unique in nuclear imaging?
What makes PET and SPECT so unique when it comes to nuclear imaging? Explanation: The dyes used in PET and SPECT are such that they become a part of the metabolic pathways and the transmitted radiations can help visualize the metabolic pathways.
How does a PET scan work video?
What are the components of PET scan?
There are 4 main components a PET scan machine, the gantry (frame) that houses the detection apparatus with a large patient port (opening), the subject table that moves in and out of the patient port allowing for a complete scan, the detector/camera system that captures the image, and a computer system that processes …
What tracer is used in PET scan?
Before your PET-CT, you’ll get a radioactive medication with glucose called a tracer through an intravenous (IV) line in your arm. This is done to show differences between healthy tissue and diseased tissue. Your PET-CT will use FDG as the tracer. FDG is taken up by your cells and doesn’t stay in your body long.
What isotope is used in PET scan?
The most commonly used isotope in PET scans is fluorine-18. It is a fluorine isotope with a half life of approximately 110 minutes.
What are the main factors affecting the resolution of PET images?
The major factors that can affect the spatial resolution of PET images include size of the detector used; colinearity, or most precisely, noncolinearity of annihilating photons; and range of emitted positrons.
What is the spatial resolution of spect?
The SPECT spatial resolution is about 6.1 mm for the 530c system and 8 mm for the D-SPECT at 10 cm. Also, there is the possibility to perform fast dynamic SPECT with both these systems, since all projections are acquired simultaneously.
What is the spatial resolution of PET imaging?
The spatial resolution of the PET images is typically ~4-5 mm, and the CT images is ~ 1 mm. This combined PET/CT scanner is a powerful tool for assessing functional and anatomical information in a single fused image for research in non-human primates.
Why does PET not need a collimator?
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). (In the gamma camera more than 99% of the emitted gamma rays are absorbed or scattered by the collimators.)
Why is fluorine 18 used in a PET scan?
Fluorine-18 This radioactive isotope of fluorine emits positrons. F-18 can be used to make a radioactive form of glucose that is readily taken up by cancer cells and other cells. Using nuclear imaging it can be used to detect tumours map brain function and detect other illness.
Can you use oxygen during a PET scan?
What does a PET scan show? A PET scan can: Measure vital functions, such as blood flow, oxygen use and blood sugar (glucose) metabolism.
What are the main factors that determine the spatial resolution of SPECT?
A large number of physical factors can affect the SPECT quantitation of a particular image feature (1), but three factors stand out: attenuation, scatter, and detector response (or finite spatial resolution limited by the collimator).
How much radiation is in a SPECT scan?
Conclusion: Total patient exposure from clinical SPECT/CT is 7mSv on average. Individual dose levels vary with the clinical indication and on-site protocol parameters.
What is PET scan PDF?
Abstract. PET is one of the widely using scan which is an imaging test that allows doctor to check for diseases in human body. It can measure blood flow, oxygen use, sugar usage, etc. PET scans are most commonly used to detect cancer, heart problems, brain disorders.
Why is PET scan more accurate than SPECT scan?
For basic research, PET is the more flexible tool, because innovative tracers are more easily synthesised for PET than for SPECT. In addition, the spatial resolution of PET is better than that of SPECT – far better. This is due to the physical nature of nuclear decay of positrons.
How are SPECT images produced?
At its most basic level, SPECT produces a 3-dimensional image of the distribution of a radioactive tracer (sometimes called a probe) injected into the bloodstream and subsequently taken up by certain tissues. [1] This is accomplished via the use of specialized nuclear medicine cameras.
Does a SPECT scan use radiation?
Radiation Risk Since the SPECT scan does use a low dose of radiation, talk with your healthcare provider if you have any concerns about your risk of exposure. No long-term health risks have been associated with using this method of imaging.