Sib nqus field uniformity (homogeneity), tseem hu ua magnetic field uniformity, yog hais txog tus kheej ntawm cov magnetic teb nyob rau hauv ib tug tshwj xeeb ntim txwv, uas yog, seb lub magnetic teb kab nyob rau hauv lub chav tsev cheeb tsam yog tib yam. Qhov tshwj xeeb ntim ntawm no feem ntau yog qhov chaw kheej kheej. Chav tsev ntawm magnetic teb uniformity yog ppm (ib feem ib lab), uas yog, qhov sib txawv ntawm qhov siab tshaj plaws teb lub zog thiab qhov tsawg kawg nkaus lub zog ntawm lub magnetic teb nyob rau hauv ib qho chaw tshwj xeeb muab faib los ntawm qhov nruab nrab lub zog teb multiplied los ntawm ib lab.
MRI yuav tsum muaj qib siab ntawm qhov sib nqus ntawm qhov sib nqus, uas txiav txim siab qhov kev daws teeb meem spatial thiab teeb liab-rau-nruab nrab ntawm cov duab hauv cov duab ntau. Qhov tsis zoo ntawm cov hlau nplaum sib nqus yuav ua rau cov duab tsis pom tseeb thiab tsis pom kev. Qhov sib nqus ntawm qhov sib nqus yog txiav txim siab los ntawm tus tsim ntawm cov hlau nplaum nws tus kheej thiab ib puag ncig sab nraud. Qhov loj dua qhov chaw duab ntawm cov hlau nplaum, qhov qis dua qhov sib nqus teb sib xws tuaj yeem ua tiav. Lub stability ntawm lub magnetic teb yog ib qho Performance index los ntsuas qhov degree ntawm drift ntawm lub magnetic teb siv nrog lub sij hawm. Thaum lub sij hawm lub sij hawm ntawm cov duab ib theem zuj zus, lub drift ntawm lub magnetic teb siv zog yuav cuam tshuam rau theem ntawm lub rov ntsuas ncha teeb liab, uas ua rau cov duab distortion thiab teeb liab-rau-suab nrov piv txo. Kev ruaj ntseg ntawm cov hlau nplaum yog ze ze rau hom hlau nplaum thiab qhov zoo ntawm kev tsim.
Cov kev cai ntawm cov qauv sib nqus sib nqus cov qauv muaj feem xyuam rau qhov loj thiab cov duab ntawm qhov ntsuas qhov chaw coj mus kuaj, thiab feem ntau siv qhov chaw kheej kheej nrog rau qee txoj kab uas hla thiab qhov nruab nrab ntawm cov hlau nplaum raws li qhov ntsuas ntau. Feem ntau, cov sawv cev ntawm qhov sib nqus ntawm qhov sib nqus yog nyob rau hauv cov ntaub ntawv ntawm ib qho chaw ntsuas, qhov kev hloov pauv ntawm qhov sib nqus qhov sib nqus hauv qhov chaw muab (ppm tus nqi), uas yog, ib lab ntawm lub ntsiab magnetic teb lub zog (ppm) Raws li ib qho kev sib txawv ntawm qhov kev nthuav qhia ntau, feem ntau qhov kev sib txawv no yog hu ua ppm, uas yog hu ua tus nqi sawv cev. Piv txwv li, lub uniformity ntawm lub magnetic teb nyob rau hauv tag nrho scanning aperture lub tog raj kheej yog 5ppm; Qhov sib nqus teb sib xws nyob rau hauv qhov chaw ntawm 40cm thiab 50cm concentric nrog lub chaw hlau nplaum yog 1ppm thiab 2ppm, feem. Nws kuj tseem tuaj yeem qhia tau tias: qhov sib txawv ntawm qhov sib nqus ntawm qhov chaw sib nqus ntawm txhua qhov cubic centimeter hauv qhov chaw kuaj hauv qab yog 0.01ppm. Txawm hais tias tus qauv, nyob rau hauv qhov kev pom zoo tias qhov ntsuas qhov loj me yog tib yam, qhov me dua tus nqi ppm qhia qhov zoo dua qhov sib nqus teb sib xws.
Nyob rau hauv cov ntaub ntawv ntawm ib tug 1.5-tMRI ntaus ntawv, lub drift fluctuation ntawm magnetic teb lub zog sawv cev los ntawm ib chav tsev ntawm deviation (1ppm) yog 1.5 × 10-6T. Nyob rau hauv lwm yam lus, nyob rau hauv ib tug 1.5T system, ib tug sib nqus teb uniformity ntawm 1ppm txhais tau hais tias lub ntsiab magnetic teb muaj ib tug drift fluctuation ntawm 1.5 × 10-6T (0.0015mT) raws li keeb kwm ntawm 1.5T magnetic teb zog. Obviously, nyob rau hauv MRI cov cuab yeej nrog txawv teb lub zog, qhov sib txawv ntawm magnetic teb siv zog sawv cev los ntawm txhua qhov sib txawv chav tsev los yog ppm txawv, los ntawm qhov kev xav no, cov tshuab tsis tshua muaj peev xwm muaj cov kev cai qis dua rau cov hlau nplaum sib nqus (saib Table 3-1) . Nrog rau cov kev cai zoo li no, tib neeg tuaj yeem siv cov qauv kev sib txig sib luag kom yooj yim sib piv cov tshuab nrog lub zog sib txawv, lossis cov tshuab sib txawv nrog tib lub zog ua haujlwm, txhawm rau txhawm rau ntsuas qhov ua tau zoo ntawm cov hlau nplaum.
Ua ntej ntsuas qhov sib nqus ntawm qhov sib nqus, nws yog qhov tsim nyog los txiav txim siab qhov nruab nrab ntawm cov hlau nplaum, thiab tom qab ntawd teeb tsa qhov ntsuas qhov ntsuas qhov ntsuas (Gauss meter) sojntsuam ntawm qhov chaw sib nqus ntawm qee lub vojvoog, thiab ntsuas nws qhov sib nqus siv. taw tes los ntawm taw tes (24 txoj kev dav hlau, 12 lub dav hlau txoj kev), thiab thaum kawg ua cov ntaub ntawv los laij cov hlau nplaum sib xws hauv tag nrho cov ntim.
Lub uniformity ntawm lub magnetic teb yuav hloov nrog ib puag ncig ib puag ncig. Txawm hais tias cov hlau nplaum tau mus txog ib qho qauv (lub Hoobkas lav tus nqi) ua ntej tawm hauv lub Hoobkas, Txawm li cas los xij, tom qab kev teeb tsa, vim muaj kev cuam tshuam ntawm ib puag ncig xws li hlau nplaum (tus kheej-) shielding, RF shielding (qhov rooj thiab qhov rais), waveguide phaj (tube), steel qauv ntawm cov hlau nplaum thiab cov kev txhawb nqa, cov khoom siv kho kom zoo nkauj, cov khoom siv teeb pom kev zoo, cov kav dej ua pa, cov kav dej tua hluav taws, cov kiv cua thaum muaj xwm txheej ceev, cov khoom siv txawb (txawm tias lub tsheb, elevators) nyob ib sab ntawm cov tsev sab saud thiab hauv qab, nws cov uniformity yuav hloov. Yog li ntawd, seb qhov uniformity ua tau raws li qhov yuav tsum tau muaj ntawm magnetic resonance imaging yuav tsum tau ua raws li qhov tseeb ntsuas qhov tshwm sim thaum lub sij hawm txais qhov kawg. Lub passive teb leveling thiab lub active field leveling ntawm lub superconducting coil ua los ntawm cov installation engineer ntawm lub magnetic resonance chaw tsim tshuaj paus nyob rau hauv lub Hoobkas los yog tsev kho mob yog cov tseem ceeb ntsuas los txhim kho lub uniformity ntawm magnetic teb.
Txhawm rau txhawm rau txheeb xyuas cov cim sau tseg hauv cov txheej txheem luam theej duab, cov cuab yeej MRI tseem yuav tsum tau ua kom pom qhov gradient magnetic teb △B nrog kev hloov pauv tas mus li thiab nce ntxiv raws li lub ntsiab sib nqus B0. Nws yog conceivable tias gradient teb △B superimposed rau ntawm ib lub voxel yuav tsum ntau tshaj lub magnetic teb sib txawv los yog drift fluctuation tshwm sim los ntawm lub ntsiab magnetic teb B0, txwv tsis pub nws yuav hloov los yog txawm annihilate lub saum toj no spatial positioning teeb liab, ua rau cov khoom qub thiab txo cov duab zoo.
Qhov ntau dua qhov sib txawv thiab kev hloov pauv ntawm cov hlau nplaum tsim los ntawm lub ntsiab sib nqus B0, qhov sib txawv ntawm cov hlau nplaum tsis zoo, cov duab tsis zoo, thiab qhov cuam tshuam ncaj qha rau lipid compression ib ntus (qhov resonance zaus sib txawv ntawm dej thiab rog hauv tib neeg lub cev tsuas yog 200Hz) thiab kev ua tiav ntawm kev soj ntsuam magnetic resonance spectroscopy (MRS). Yog li, kev sib nqus teb sib nqus yog ib qho ntawm cov cim tseem ceeb los ntsuas kev ua haujlwm ntawm MRI cov cuab yeej.
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High-pressure contrast media injectors kuj tseem yog cov cuab yeej pabcuam tseem ceeb hauv kev kho mob cov duab thiab feem ntau siv los pab cov neeg ua haujlwm kho mob xa cov xov xwm sib txawv rau cov neeg mob. LnkMed yog cov chaw tsim khoom nyob hauv Shenzhen uas tshwj xeeb hauv kev tsim cov khoom siv kho mob no. Txij li thaum xyoo 2018, lub tuam txhab cov kws tshaj lij pab pawg tau tsom mus rau kev tshawb fawb thiab tsim cov khoom siv hluav taws xob zoo sib xws. Tus thawj coj pab pawg yog tus kws kho mob nrog ntau tshaj kaum xyoo ntawm R & D kev paub. Cov kev paub zoo ntawm noCT ib leeg injector,CT ob lub taub hau injector,MRI txhaj tshuajthiabAngiography siab injector(DSA txhaj tshuaj) uas tsim los ntawm LnkMed kuj txheeb xyuas qhov kev tshaj lij ntawm peb pab pawg kws tshaj lij - kev tsim qauv tsim thiab yooj yim, cov ntaub ntawv ruaj khov, ua haujlwm zoo meej, thiab lwm yam, tau raug muag rau cov tsev kho mob loj hauv tsev thiab kev lag luam txawv teb chaws.
Post lub sij hawm: Mar-28-2024
