Video: MRI homogeneity yog dab tsi?
2024 Tus sau: Miles Stephen | [email protected]. Kawg hloov kho: 2023-12-15 23:36
Homogeneity yog hais txog qhov sib txawv ntawm qhov sib nqus ntawm qhov chaw ntawm lub tshuab luam ntawv thaum tsis muaj tus neeg mob nyob. Sib nqus teb homogeneity yog ntsuas nyob rau hauv qhov chaw ib lab (ppm) tshaj ib lub cheeb ntawm spherical ntim (DSV).
Raws li txoj cai, MRI shimming yog dab tsi?
Shimming yog cov txheej txheem uas lub ntsiab magnetic teb (Bo) yog ua ntau homogenous. Shimming tej zaum yuav passive, nquag, los yog ob qho tib si. Nyob rau hauv passive shimming Cov ntawv me me ntawm cov ntawv hlau los yog ferromagnetic pellets yog affixed ntawm ntau qhov chaw nyob rau hauv lub scanner bore.
Tsis tas li ntawd, dab tsi yog ib qho chaw sib nqus sib nqus? Uniform Magnetic Field : Sib nqus teb yog hais tias yog khaub ncaws yog tias Sib nqus induction muaj tib qhov loj thiab tib qhov kev taw qhia ntawm txhua lub ntsiab lus hauv cheeb tsam. Thaum tam sim no ntws thoob plaws lub kauj a uniform magnetic teb yuav subsist tag nrho raws li muaj los ntawm cov kauj.
Kuj tseem yuav paub, dab tsi yog tus lej slew hauv MRI?
Sib piv 1.5T MRI Gradient Slew Rates . A slew nqi yog qhov ceev ntawm qhov gradient mus txog nws qhov siab tshaj plaws amplitude. Nws tseem hu ua lub sijhawm sawv. Nws ntsuas hauv millitesla ib 'meter' ib microsecond lossis mT/m/ms. Qhov siab dua slew nqi , lub thinner lub anatomical hlais.
ATM shimming yog dab tsi?
Tsib tus scammers raug ntes lub hli tas los hauv California, raug liam tias " shimming "ntawm ATM cov tshuab thiab cov kws tshaj lij tau ceeb toom rau cov neeg siv khoom kom ceev faj tiv thaiv qhov kev hem thawj tshiab no. ' Shimming ' yog qhov hloov tshiab ntawm skimming, ib qho kev dag ntxias uas cov tub sab muab ib lub cuab yeej rau cov neeg nyeem daim npav rho nyiaj ntawm qhov chaw xws li chaw nres tsheb roj.
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Gradints tsuas yog cov hlua ntawm cov xaim lossis cov ntawv nyias nyias ntawm lub plhaub cylindrical uas nyob hauv lub bore ntawm MRI Scanner. Qhov no gradient teb distorts lub ntsiab magnetic teb nyob rau hauv ib tug me ntsis tab sis kwv yees tus qauv. Qhov no ua rau lub resonance zaus ntawm protons txawv nyob rau hauv ib txoj hauj lwm ntawm txoj hauj lwm