PET handout - PET Imaging PET Imaging Zhenghong Lee, Ph.D....

Info iconThis preview shows pages 1–15. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: PET Imaging PET Imaging Zhenghong Lee, Ph.D. Case Western Reserve University Department of Biomedical Engineering University Hospitals Case Medical Center Nuclear Medicine, Department of Radiology Scintillation Crystal Scintillation Crystal Thickness nergy Dependence Energy Dependence Resolution and Sensitivity Trade off Crystal Types LSO, NaI, CsI, BGO Parameter NaI(Tl) CsI(Tl) BGO LSO Effective Atomic Number 51 75 66 Density(gm/cc) 3.67 4.51 7.13 7.4 y(g ) Decay Time ns 230 600 to 340 300 48 Light Output (NaI(Tl) = 100) 100 45 15 75 PET/SPECT Radio PET/SPECT Radio-Nuclides Nuclides PET Nuclides PET Nuclides Labeling compound with positron emitting nuclide rovides means for Nuclide Halflife provides means for detecting in vivo concentration of 15 O 122 sec 13 97 min compound N 9.97 min 11 C 20.48 min 18 F 109.74 min PET Imaging PET Imaging By detecting photons emitted from radioactive compound, PET can measure tissue radioactivity concentration noninvasively Radioactivity concentration reflects physiologic function/biochemistry probed by radiopharmaceutical Time sequence of images yields in vivo tissue pharmacokinetics Clinical PET Scanner Clinical PET Scanner Siemens/CTI ECAT PET Scanner PET Detector Rings w/ close-up electronics ositron Decay & Annihilation ositron Decay & Annihilation Positron Decay & Annihilation Positron Decay & Annihilation racer decays and emits positron Tracer decays and emits positron 511 keV (Tracer) Annihilation occurs with an electron Positron travels ~0.25 mm 18 F, 2.6 mm 82 Rb ~.25-3mm Conservation of energy E & momentum M- M E = 2 x 511 keV ( + and - ) nnihilation results in a pair of p otons Annihilation results in a pair of photons- Created simultaneously- Trajectories 180 o ( 0.3 FWHM) 511 keV- Energies = 2 x 511 keV ( 1 and 2 ) Photons pairs detected in temporal coincidence Reconstruction yields tracer distribution P is for positron is for positron 18 F, 11 C, 13 N, 15 O nucleus decays, ejecting a positron Positron meets with electron: annihilation Example: Example: 18 18 F ( F ( + , EC) , EC) ompetitive + EC: 97% + 3% EC Competitive , EC: 97% , 3% EC Positron Ranges Positron Ranges E is for emission is for emission 0.511 MeV 0.511 MeV Two photons are emitted Photons headed in opposite directions (conservation of E and ) Emitted are detected by scanner T is for tomography is for tomography Photons detected in temporal coincidence are recorded as projection data that are tomographically reconstructed to reveal spatial distribution of radioactivity in subject Tomographic Reconstruction Tomographic Reconstruction Filtered Backprojection erative Methods Iterative Methods Examples L- M = Maximum Likelihood Expectation Maximization ML EM Maximum Likelihood Expectation Maximization OS-EM = Ordered Subsets Expectation Maximization Iterative Reconstruction Iterative Reconstruction...
View Full Document

This note was uploaded on 01/16/2011 for the course EBME 320 taught by Professor Mult during the Fall '10 term at Case Western.

Page1 / 72

PET handout - PET Imaging PET Imaging Zhenghong Lee, Ph.D....

This preview shows document pages 1 - 15. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online