Download - PET/ CT [Positron Emission Tomography]
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NIDUNG
Gii thiu
PET v dc chtphng x
CT
ng dngPET/CT
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GII THIU
PET==Positron Emission Tomography.
Nm1945:bt uc nhngnghin cu v ng dng capositron trong lnh vcy hc.
Nm1951: cc nh khoa hc ca bnh vinMassachusetts thc hin vicghi nhpositronbng k thuttrng phng.
T nm 1992 n nay: kt hp gia chp nh cu trc(CT) v chp nh chc nng (PET), my PET/CT rai.
PET
CT Hnhchc nng
Hnhcu trc
Hnhcu trc vchc nng
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Mtpositron pht ra t htnhn nguyn t tn ti rt ngn, ch i c mtqungng cc ngn ri kt hp vi mt in t tdo tch inm trong m v vo mttrngthi kch thch gil positronium. Positronium tn ti rt ngnv gn nhngay lp tc chuynho thnh 2 photon cnang lng511 keV v pht ra theo 2 chiu ngcnhau trn cng mt trc vi imxutpht Ngita gi l hin tng hu ht(annihilation).
Nu t 2 detector i din ngun pht positron v dng mch trng phng(coincidence) th c thghi nhn2 photon ng thi . Do vycc u m nhpnhy c thxc nh vtr pht ra positron (cacc photon ). Vtr phi nmtrn ng ni lin2 detectorghi nhnchng.Ngita gi l ngtrng phng (coincidence line). Trong cng mt thi im my c thghi nhn chng triu s liu nh vy, to
nn hinh anh phn b hot phng x(PX) trong khng gian ca i tng nhduPX trc (thu thpdu liuv ti tohinh anh).
I.1 NGUYNLPET
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detector
detector
e-
e+
Ht nhn khngbn
pht positronPositron kt hpelectron v hy
2 gama 511 keV
ngc nhau
Trng phng tht
I.1 NGUYNLPET
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I.2 CU TO PET
CT
PET
CT PET
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MCH IN TTRNG PHNG
400-650 keV
4-16 ns
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My PET hin ibao gm mts lng lncc tinh th(4000n24.000) c sp xp thnhhnh tr gm ccvng ring lvi ng knh vng in hnh85 cm v trc trng chiu l16 cm. Cc vng N tinh thxc nh tng cng2N-1 lt (ticctrung tm vng v ti im
gia cacc vng). Kch thcvtl ca mitinh th thngl4-8 mm mt ct ngang v dy t20 n30 mm
Trng phng tht(T),Trng phng ngu nhin (R),Trng phng tn x(S).
I.2 CU TO PET
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Cc tinh th thng c dng trong my PET nh:
Sodium iode pha thm tp cht thallium: NaI(Tl)
Bismuth germinate hay BGO: Bi4Ge3O12
Lutetium oxyorthosilicate pha thm tp cht Cerium hay LSO:Lu2SiO5(Ce)
Ytrium oxyorthosilicate pha thm tp cht Cerium hay YSO:Y2SiO5(Ce)
Gadolinium oxyorthosilicate pha thm tp cht Cerium hayGSO: Gd2SiO5(Ce)
Barium fluoride: BaF2
Cesium fluoride: CsF
I.2 CU TO PET
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Tinh th no c s dng cn ty thuc thit b ang sdng cn tc m cao hay phn gii hnh nh cao,thng da trn nhng c im sau y ca tinh th:
nhy cadetector
Tc m ngu nhin
Tc m tn x
Hiu sutnh sng
Thigian pht x nhpnhy
I.2 CU TO PET
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CC TNG TC CA CA PHOTON GAMMA VI
M C TH
C 3 kiu tngtc chnh: Hiu ng quang in (nng lng gamma