Positron flight in human tissues and its influence on PET image spatial resolution

摘要: The influence of the positron distance flight in various human tissues on spatial resolution emission tomography (PET) was assessed for positrons from carbon-11, nitrogen-13, oxygen-15, fluo- rine-18, gallium-68 and rubidium-82. investigation performed using Monte Carlo code PENELOPE to simulate transport within com- pact bone, adipose, soft lung tissue. simulations yielded 3D distributions annihilation origins that were projected image plane order assess their im- PET resolution. ob- tained cusp-shaped with long tails rather than Gaussian shaped, thus making conventional full width at half maximum (FWHM) measures uncertain. 20% amplitude (FW20M) more appropriate values root mean square addition loss components. Large differences losses due found selected radionuclides. contribu- tion blur be up three times larg- er tissue or fat five larger bone For 18 F, 0.54 mm 1.52 tissue, compared 4.10 10.5 mm, respectively, 82Rb. With as a possible exception, all has minor impact cameras spa- tial 5-7 are used combination F-labelled radiopharmaceuticals. However, when ultra- high cameras, 3-4 resolution, applied, especially other radionuclides, may enter limiting factor total resolution— particularly