Decreasing the thickness of the crystal improves resolution, though it also decreases the efficiency of detection. The other options would actually decrease the spatial resolution of the camera
Increasing the distance between the lead septa in the collimator
Increasing the distance between the patient and the camera
None of the other choices
Decreasing the length of the lead septa in the collimator
Decreasing the thickness of the scintillation crystal
They differ only in numbers of neutrons, which makes their atomic mass differ but not their chemical behavior
II and III
I and III
I and II
I, II, and III
All are true.
PET is not based on a projection modality, though SPECT is. PET does not require the use of collimators, though SPECT does.
I and II.
I and III.
I, II, and III.
At high atomic numbers the number of neutrons tends to be larger than the number of protons.
II and III.
CT uses x-rays and Nuclear Medicine uses gamma rays, both being high energy photons whose spectra actually overlap.
CT relies on transmission through the body and Nuclear Medicine on emission from within the body.
Both modalities involve radiation risk to the patien
CT generally images anatomy with relatively high resolution and Nuclear Medicine generally images physiological function with relatively low resolution.
All are true
All statements are true.
In nuclear medicine, attenuation is unwanted, since the total radioactivity is the desired imaging parameter. In CT or planar X-ray images, radiation is introduced from outside and attenuation measured.
tomographic slices may be reconstructed by combining radiation detected along multiple linear paths
signal can be increased by increasing the radiation dose
attenuation by tissue is the desired imaging parameter.
one ore more crystals are used to convert high energy photons into light photons.
electromagnetic radiation, not particulate radiation, is used to image.
Individual gamma photons are indeed counted and located.
Multiple photomultiplier tubes are arranged in a grid behind a large crystal that act in concert to determine the location of the incoming photons with a spatial resolution greater than that of the tubes.
The contribution from Compton scattering to the image is reduced by analyzing the pulse height of the combined responses of the photomultiplier tubes to each detected gamma particle.
Average rates, rather than individual counts, of the gamma photons are all that are measured.
Lead septa are required to generate a projection image
Each gamma particle produces a scintillation consisting of many light photons.
The primarily anatomical higher-resolution information from the CT scanner is combined with the primarily physiological lower-resolution information from the PET scanner.
The CT scanner is used to determine the attenuation along each Line of Response in the PET scanner.
The primarily anatomical, lower-resolution information from the CT scanner is combined with the primarily physiological, higher-resolution information from the PET scanner.
Registration of the two imaging modalities is greatly facilitated since the patient only needs to be slid a short distance between the actual scanners.
Virtually every PET scanner sold today also contains a CT scanner.
Statement II is false. This is an example of metastable isomeric transition, not beta-decay
: The primarily anatomical higher-resolution information from the CT scanner is combined with the primarily physiological lower-resolution information from the PET scanner.
The primarily physiological, higher-resolution information from the CT scanner is combined with the primarily anatomical, lower-resolution information from the PET scanner.
The CT scanner is used to determine the attenuation along each Line of Response in the PET scanner
Lead septa are indeed required to generate a projection image.
Individual gamma photons are counted and located.
Lead septa are not required to generate a projection image.
They include atoms with low atomic number typically found in normal organic molecules, such as carbon and oxygen.
They are used in devices that nowadays typically also contain a CT scanner.
Their decay leads to the generation of antimatter and subsequently to the creation of two 511 keV gamma photons moving in directions approximately 180 degrees apart.
They are unstable because they have too few neutrons.
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너는 시간이 없어.
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