What is the resolution of SPECT?
What is the resolution of SPECT?
Recently developed single photon emission computed tomographic (SPECT) scanners dedicated for small animal imaging are of interest due to their excellent spatial resolution of <1 mm, but few studies have focused on the evaluation of intratumoral heterogeneity.
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).
Why collimator is used in SPECT?
A collimator is a device used to restrict the photon acceptance angle to provide positional information for detected photons. A SPECT collimator is a thick sheet of metal of high atomic number, usually lead or tungsten, pierced by an array of holes.
What collimator is typically used in SPECT imaging?
The most commonly used radionuclide for SPECT is 99m-technetium (99mTc), which has a main photo peak at 140.5 keV and a half-life of 6.01 h.
What affects SPECT image quality?
Several factors affect the quality of SPECT images (e.g., resolution and noise) and the ability to perform absolute quantification (e.g., attenuation, scatter, motion, and resolution).
Does SPECT have good spatial resolution?
Unlike in clinics, preclinical SPECT outperforms preclinical coincidence PET in terms of resolution (best spatial resolution of SPECT – 0.25mm, PET ≈ 1 mm ) and, at the same time, allows to perform fast dynamic imaging of animals (less than 15s time frames).
What is high energy general purpose collimator?
The Ultra-High Energy General Purpose Collimator (UHGP) is intended to be used to detect and image the distribution of high-energy photons from an administered positron-emitting radioactive agent in the human body, specifically cardiac imaging.
What determines the energy of a collimator?
The resolution and sensitivity of collimators are determined by septal thickness, septal material, hole size, and bore length. Not all photons that pass through the collimator are wanted photons. Some photons passed by a collimator have desired directions of travel but do not have desired energies.
How better image resolution can be obtained in SPECT?
Higher SPECT resolution will be achieved with the smaller pixel size of 128 × 128 (pixel size = 4.51 mm) matrices than with a pixel size of 64 × 64 (pixel size = 9.02 mm) matrices. This can be achieved by using the SPECT phantom (Fig. 1).
What is the role of filters in SPECT images?
The goal of filtering in tomographic images is to suppress statistical noise and simultaneously to preserve spatial resolution and contrast. The aim of this work is to describe the most widely used filters in SPECT applications and how these affect the image quality.
What is spatial resolution in SPECT?
The basic detector element of a clinical SPECT system is based on the Anger camera, which offers a spatial resolution of 4–6 mm [1]. A typical camera consists of an array of photomultiplier tubes that have their entrance windows coupled by light guide to a large plate of a crystal scintillator material.
Which detector has very good resolution and efficiency?
High purity germanium detector has better resolution compared to the scintillation type of detector, Sodium iodide (NaI). The HPGe detector offers the advantage of resolving two closely located energy points and has the ability to detect a mixture of nuclear material.
Why does detector efficiency decrease with energy?
The efficiency decreases with increasing energy because the probability that the photon will interact within the detector also decreases with energy.
How can the resolution of the collimator be increased?
Explanation: The resolution of the collimator can be increased by reducing the separation between the metal plates of the collimator.
Is SPECT same as gamma camera?
Overview. SPECT (Single-Photon Emission Computed Tomography) is a diagnostic imaging technique used in nuclear medicine which studies PHYSIOLOGICAL (FUNCTIONAL) processes in the body. Gamma cameras are used to construct an image of the distribution of radiopharmaceuticals spread out in the body of a patient.
Do energy resolution models affect energy spectra for isotopes with multiple photopeaks?
The voxel-based digital patient phantom energy spectra, simulated with the fittedand theoreticalmodels, showed the potential impact of an incorrect energy resolution model when simulating isotopes with multiple photopeaks. Conclusion
How does energy resolution affect the accuracy of simulated images?
Any under- or overestimation of the energy resolution can ultimately affect the accuracy of the simulated image, which may lead to poor agreement between measured and simulated images. Inaccuracies could influence the quantification accuracy of simulated images, which is vital in the process of performing internal dosimetry [17, 18].
Is 177 Lu SPECT quantitatively accurate using both energy windows?
It is hypothesized that quantitatively accurate 177 Lu SPECT can be achieved using both energy windows when the appropriate combination of collimator and scatter correction technique is used.
What is the resolution of intrinsic energy spectra?
Intrinsic energy spectra, with a digital resolution of 1.3 keV per channel, were acquired to obtain 30 000 counts in the channel with the highest count contribution. All intrinsic energy spectra acquisitions were repeated three times.