- 1.BS V NGUYN THNH NHN BS PHAN THANH HI BS NGUYN VN CNG
2. I TNG QUAN 1 Vai tr ca ct lp in ton (CLT). 3. CLT cho php chn
on trong chn thng v bnh l nhanh hn, an ton v chnh xc cao Hnh nh CT
cng ng mt vai tr quan trng trong xy dng, lp k hoch iu tr v theo di
bnh ung th. Do s lng chp CLT tng mnh. 4. Chp CLT chim mt na trong
tip xc bc x trong y t. Gim liu bc x trong chp ct lp in ton phi c u
tin. S dng thch hp cho tng bnh nhn. Bs lm sng v Xquang chia s trch
nhim. Chp CLVT phi c thc hin ti u ha nguyn tc ALARA 5. II. Liu bc x
trong chp ct lp in ton v nguy c lin quan Ch s liu CLT (CTDI vol) L
liu x a vo bnh nhn trong mt vng qut. n v s dng l mGy. Vn tc di
chuyn bn phi c xem xt. CTDIvol = CTDIw x 1/pitch di kho st cng rt
quan trng DLP = CTDIvol L 6. Liu c quan (Organ dose) Liu hiu qu
(Effective dose) CT* Effective dose (mSv) Head CT 12 Chest CT 57
Abdomen CT 57 Abdomen and pelvis CT 814 Coronary CT angiography 515
Coronary calcium CT 13 7. Nguy c lin quan 8. Liu thp c nh ngha km
hn 100 mSv. Mt s nghin cu cho rng liu thp cng c nguy c gia tng ung
th v sau. 9. Cht lng hnh nh v bc x liu Liu bc x l mt trong nhng yu
t quan trng nht quyt nh cht lng hnh nh CLT Liu bc x ch nn c gim vi
iu kin l cht lng hnh nh vn m bo chn on 10. Mc tiu gim liu c th c
tip cn t hai quan im sau y. t cht lng hnh nh cho tng k thut chn on
c th, khng i hi phi c phn gii khng gian cao hn mc cn thit. Gim liu
m khng lm gim cht lng hnh nh. Nhim v ny c th c thc hin bng cch ti u
ha h thng CLT v k thut v x l d liu. 11. III.CC CHIN LC GIM LIU. Ti
u ha h thng CT Phm v qut Kim sot cng t ng Hiu in th ti u. Kim sot
phn gii trong xy dng li v x l d liu M phng liu thp. Ti to hnh nh lp
i lp li. 12. 1 Ti u ha h thng CLT Detector Detector c l l yu t quyt
nh quan trng nht ca hiu sut liu ca mt h thng CLT Gim mc nhiu nhm
nng cao cht lng hnh nh trong chp CLT liu thp, i hi s tinh t ca tt c
cc linh kin in t trong h thng detector 13. Collimators Tin b gn y
trong thit k collimator lin quan n vic gim s lng overscanning trong
CT xon c Ngoi gii php phn mm cn c gii php phn cng chun trc t ng ngn
chn cc tia X-quang khng cn thit Gim liu ln n 40%, c bit i vi cng
cao v phm vi qut nh 14. B lc tia nh hnh L mt yu t quan trng i vi
hiu sut liu ca mt h thng CLT Nhiu b lc mi cho cc ng dng lm sng khc
nhau, bao gm: u, thn, nhi khoa v tim c s dng trong th h CLT hin i
gim liu bc x ngoi vi. 15. 2 Phm vi qut Lin quan trc tip n tng liu
bc x bnh nhn Gi cho phm vi qut cng nh cng tt. y c l l phng php n
gin nht gi cho liu thp nht c th. 16. 3 Kim sot cng t ng 17. Mc ch
ca AEC l s dng mc bc x ti u cho bnh nhn t c cht lng hnh nh tt chn
on 18. 4 Hiu in th ti u. S dng hiu in th thp gim liu v ci thin cht
lng hnh nh. Gim hiu in th s cho hnh nh c tng phn cao nhng hnh s b
nhiu (noise) nhiu hn. Hiu in th ti u ph thuc vo kch thc bnh nhn v
mc nh chn on c th. 19. Cht lng hnh nh ci thin v gim 23% liu x 20. 5
Kim sot phn gii trong xy dng li v x l d liu Vic gim liu ch yu b gii
hn bi nhiu hnh nh ti a cho php. X l d liu v xy dng li hnh nh l phng
php ti u c th to ra hnh nh vi nhiu thp hn m khng b mt cc thuc tnh
hnh nh Khng nhng ci thin cht lng hnh nh m cn gim liu bc x. 21. 6 M
phng liu thp. Mt cu hi ph bin trong chp CLT l gim lng phng x bao
nhiu m khng b mt cc thng tin chn on? 22. 7 Ti to hnh nh lp i lp li
Iris, Safire ( Siemens) AIDR 3D Integrated ( Toshiba Aquilion One )
23. S pht trin mi nht gim liu t ng khi chp CLT Ti to hnh nh lp i lp
li c thc hin vi thut ton ti to tin tin lp i lp li trong hai phn.
Phn u tin loi b xo nh trong d liu th 3D. Tip theo l gim hnh nh nhiu
lp i lp li ln th hai trong qu trnh ti to hnh nh Gim ln n 75% so vi
mt my CLT truyn thng. 24. Chp CLT tr em. 25. Gim thiu liu bc x
trong chp CLT nhi l c bit quan trng. Gim liu bc x trong CLT nhi: nh
gi cn thn cc nguy c v li ch ca CLT cho tng bnh nhn Cc thng s k thut
dng cho nhi phi c thc hin. Gim mAs cho tr s sinh Gim hiu in th (kV)
26. Chp CLT tim CT tim bao gm mt lot cc ng dng mi lm sng: nh gi ca
bnh ng mch vnh vi ha thnh ng mch vnh canxi im (calci score) Cu ni
Chc nng tht Van tim Kh nng tn ti / nhi mu v ti mu c tim 27. CLT ng
mch vnh i hi phn gim thi gian v khng gian tt. ECG-gated xon c c s
dng ph bin trong CT tim ch yu l do s n nh v tnh linh hot ECG
tube-current pulsing gim liu n 64% m khng b mt cht lng hnh nh 28.
Aquilion One 320 detector ( 640 slices ) vi mt dy detector rng 16
cm, thit k ny cho php kho st ton b tri tim trong mt vng xoay duy
nht v mt chu k tim. Liu tia x v liu thuc cn quang cc thp (rt c li
cho bnh nhn, c bit l bnh nhi). 29. - Bnh nhn n, 44 tui, cn nng 55
kg, au ngc tri v c tin cn cao huyt p nh. - Lng thuc cn quang
Ultravist 55ml. - Liu tia /CTA: 0.9mSv (Nhp tim 60 l/p nn ch chn v
pht tia cc i ti pha tm trng 70-80%) 30. ng mch vnh xung trc tri 31.
ng mch vnh phi 32. Bnh nhn nam, 83 tui Tin cn: Tng huyt p, T2 SA
tim v ECG: Rung nh, TMCT Thuc cn quang dng: 70ml Liu tia xa/CTA:
2.1 mSv 33. Vi ha km x va nh LAD 34. Vi ha km x va nh LCX 35. IV.
KT LUN Gi bc x liu thp hp l c th c (ALARA) l nguyn tc trong chp CLT
S ra i ca cng ngh mi, gim liu ng k trong chp CLT cc nguy c lin quan
cng gim, kt qu l ci thin hn na t l li ch / nguy c My CT th h mi:
Siemens: Somatoma dual score, 128 slices Toshiba: Aquilion One,
Prime, Premium Philip: Brilliance 36. Referens 1- Lifeng Yu, Xin
Liu, Shuai Leng, James M Kofler, Juan C Ramirez- Giraldo, Mingliang
Qu, Jodie Christner, Joel G Fletcher, and Cynthia H McCollough
Radiation dose reduction in computed tomography: techniques and
future perspective Imaging Med. 2009 October ; 1(1): 6584.
doi:10.2217/ii 2 Cynthia H. McCollough, PhDa, Andrew N. Primak,
PhDb, Natalie Braunc, James Kofler,PhDd, Lifeng Yu, PhDd, and Jodie
Christner, PhD. Strategies for Reducing Radiation Dose in CT Radiol
Clin North Am. 2009 January ; 47(1): 2740.
doi:10.1016/j.rcl.2008.10.006. 3 R. Irwan , S. Nakanishi, A. Blum
AIDR 3D - Reduces Dose and Simultaneously Improves Image Quality,
Toshiba 4 Approaches to Dose Reduction in Computed Tomography,
Siemens. 37. MEDIC
