What is Noise Equivalent Count rate?
Introduction: Noise-equivalent count rate (NECR) is a performance metric that is used to evaluate the performance of PET scanners (Strother 1990). Conventionally, NECR is measured by scanning the NEMA NU 2 scatter phantom (20 cm diameter x 70 cm long). the count rate and noise properties in the scanner.
What is Sinogram PET?
If a large number of LORs are plotted from the same point (or pixel), the resulting graph is half of a sine wave turned on its side, as shown in Figure 1B. This graph is appropriately referred to as a “sinogram.” The location of the point in the transverse plane (e.g., the location of the tumor in Fig.
Does a PET scan have high spatial resolution?
It features both high sensitivity (~ 10%) and high spatial resolution (1.4 mm FWHM with filtered back projection reconstruction). In addition, it is particularly well suited to whole body imaging of mice and rats: the bore is 12 cm, with an active transaxial field of view (FOV) of 10 cm and an axial FOV of 12.7 cm.
What is Time of Flight in PET?
By the early 1980s, fully functional TOF PET systems had been built, not long after the first conventional PET systems were completed. The concept of time-of-flight means simply that for each annihilation event, we note the precise time that each of the coincident photons is detected and calculate the dif- ference.
How far can positrons travel in air?
In air, the tso positrons at Emax can travel over 6 m and H2Rb positrons at Emax can travel almost 12 m before being totally absorbed.
What is positron range?
The positron range introduces uncertainty in the position of the positron emitter, resulting in blurring of the PET images. This effect is very clearly seen for high-energy emitters such as 82Rb, and also for less energetic emitters in small-animal PET imaging where blurring on a millimetre scale is important.
What is Sinogram in CT?
A sinogram is a special x-ray procedure that is done to visualize any abnormal opening (sinus) in the body, following the injection of contrast media (x-ray dye) into the opening.
What is a Sinogram in nuclear medicine?
The sinogram provides a convenient way to represent the full set of data acquired during a scan and can be useful for determining the causes of artifacts in SPECT or PET images. FIGURE 16-4 Two-dimensional (2-D) intensity display of a set of projection profiles, known as a sinogram.
Do PET scans have low resolution?
Compared with CT, 18F-FDG PET scans have lower spatial resolution and higher levels of noise and require significantly longer imaging times, result- ing in low patient throughput.
Does PET have good temporal resolution?
Other important imaging modalities are PET and Optical Imaging. PET’s spatial resolution typically falls somewhere between that of fMRI and MEG/EEG. In addition, PET has very low temporal resolution (tens of seconds to minutes) and requires injection of a trace amount of radioactivity.
What is a PET tracer?
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 does TOF detection enhance PET?
TOF reconstruction leads to a higher contrast recovery at matched noise with faster and more uniform convergence, and the benefit is even greater for larger patients. This paper attempts to quantify the TOF benefit using clinical data and shows results that are consistent with the phantom studies.