Siêu âm tổng quát

"Siêu âm tổng quát 🔙 Quay lại trang tải sách pdf ebook Siêu âm tổng quát Ebooks Nhóm Zalo K M . 0 0 7 1 7 0 PGS.TS PHAM MINH THONG C h u b ie n S l E U AM TONG QUAT / V NHA XUAT BAN BAI HOC HUE SlEU AM t 6 ng quat PGS.TS PHAM MINH THONG Chu bien SlEU AM t 6ng q u at NHA XUAT BAN DAI HOC HUE HUE BIEN MUC TREN XUAT BAN PHAM CUA THU VIEN QUOC GIA VIET NAM Sieu am tong quat / Pham Minh Thong chu bien... [va cong sir]. Hue: Dai hoc Hue, 2011. - 602tr Thif muc cuoi sach. 1. Y hoc 2. Sieu am 616.07- d c l4 DUEOOlOp-CIP o ©2011. hy Cao Tran JSC and Pham Minh Thong et al. Ma so sach: TK /176-2010 Ban quyen cuon sach nay difOc siCr hOi Cong t\ co phan Cao Tran \ a cac lac gia. Nghiem cam moi hinh tlurc sao chop, nhan ban kinh doanh diroi hat k\ hinh [hue nao. Moi you cau thong tin \in gifi \ e Cong ty co phan Cao Tran. 27/10 pho \"inh Tuy, quan Hai Ba Trifng, thanh pho Ha Noi, Viet Nam . Dien thoai: 043 987 0580, 090 452 8001. Email: caotran inc(o' vahoo.com . MUC LUC • • Cac tac gia Lori noi dau Left giofi thieu V ^ / 1. Dai cifcfng ve sieu am chan doan----------------------------------------------------------------1 PGS.TS Pham Minh Thong 2. Nhieu anh tren sieu a m ------------------------------------------------------------ -------------37 PGS.TS Pham Minh Thong ThS Pham Hong Dufc 3. Giai phau sieu am gan va dtfcfng m at------------------------------------------------------- 49 PGS.TS Pham Minh Thong ThS Pham Hong Due 4. Sieu am gan — --------------------------------------------------------------------------------------69 PGS.TS Pham Minh Thong ThS Pham Hong Due 5. Sieu am difcfng m at-------------------------------------------------------------------------------123 PGS.TS Pham Minh Thong ThS Pham Hong Due 6. Sieu am tuy-------------------------------------------------------------------------------------------159 ThS Pham Hong Dufc vi Muc luc 7. Sieu am la c h ----------------------------------------------------------------------------------------181 ThS Nguyen Khoi Viet 8. Sieu am dong mach chii bung vafinh mach chu dtfdi ------------------------------ 209 PGS.TS Pham Minh Thong 9. Sieu am he tiet nieu-------------------------------------------------------------------------------231 • • ThS Pham Hong Due ThS Le Anh Tuan 10. Sieu am tien liet tu yen -------------------------------------------------------------------------- 251 PGS.TS Pham Minh .Thong Th.S Nguyen Khoi Viet 11. Sieu am tinh h o a n -------------------------------------------------------------------------------- 273 PGS.TS Pham Minh -Thong Th.S Nguyen Khoi Viet 12. Sieu am khoang sau phuc m ac--------------------------------------------------------------- 303 PGS.TS Pham Minh Thong Th.S Vu Thanh Trung 13. Sieu am tuyen thtfcfng th an --------------------------------------------------------------------321 PGS.TS Pham Minh Thong Th.S Vu Thanh Trung 14. Sieu am ong tieu h o a ----------------------------------------------------------------------------- 331 ThS Nguyen Duy Trinh 15. Sieu am phu khoa----------------------------------------------------------------------------------361 ThS Nguyen Xuan Hien 16. Sieu am san k h o a ----------------------------------------------------------------------------------381 TS. Le Hoang 17. Sieu am xtfcfng khoTp, phan mem (cd quan van d o n g )------------------------------- 405 TS. Bui Van Giang 18. Sieu am vu-------------------------------------------------------------------------------------------- 431 PGS.TS Pham Minh Thong Th.S Nguyen Thu Huong Muc luc vii 19. Sieu am tuyen g ia p ------------------------------------------------------------------------------ 453 PGS.TS Pham Minh Thong Th.S Dao Danh VTnh / s / / 20. Sieu am mat va hoc m at------------------------------------------------------------------------491 ThS. Vu Dang Liru Thtfmuc tham k h a o ----------------------------------------------------------------------------------531 Chi muc (Ind ex)-----------------------------------------------------------------------------------------537 viii Muc luc CAC TAC GIA PG S.TS P ham M inh T hong (Chu bien) Pho Giam doc Benh vien Bach mai. Trifling Khoa Chan doan Hinh anh - Benh vien Bach mai. Pho trifling Bo mon Chan doan Hinh anh - Trifting Dai hoc Y Ha Noi. Pho chu tich kiem Tong thif ky Hoi Dien quang va Y hoc Hat nhan Viet nam. Chu tich chi Hoi Dien quang can thiep Viet nam. T S. B i i V an G iang Trifling khoa Chan doan Hinh anh - Bcnh vien Saint-Paul. •> Giang vien Bo mon Chan doan Hinh anh - Trifling Dai hoc Y Ha noi. TS. L k H oang Trifling phong chi dao tuyen - Benh vien Phu san Trung UOng. T h S. N g i vfeN X i an H i£ n Bac sy chuyen khoa Chan doan Hinh anh - Benh vien Bach mai. T h S. P ham H ong Di'c Giang \ icn Bo mon Chan doan Hmh anh - Trifling Dai hoc Y Ha noi. T h S. L e A n h T i an Bac sy chuyen khoa Chan doan Hinh anh - Benh vien Bach mai. T h S. N g i yen D i y T rinh Bac sy chuyen khoa Chan doan Hinh anh - Benh vien Bach mai. x Cac tac gia ThS. VC D a n g L i t Giang vien Bo mon Chan doan Hinh anh - TrUOng Dai hoc Y Ha noi. T h S. N gl vfeN K hoi V iet Bac sy chuyen khoa Chan doan Hinh anh - Benh vien Bach mai. T h S. VC T hanh T rung 7 x v •> Bac sy chuyen khoa Chan doan Hinh anh - Benh vien Bach mai T h S. D a o D anh VIn h •> Bac sy chuyen khoa Chan doan Hinh anh - Benh vien Bach mai. T h S. N guyen T h u H l'cJn g ✓ 1 V 1 Bac sy chuyen khoa Chan doan Hinh anh - Benh vien Bach mai. LOI NOI DAU sieu Am c h a n d o a n l a m o t p h An q u a n trong trong hinh anh v hoc, no la phirong phap tham kham khong chav mau, khong gav nguv hiem cho benh nhan va thav thuoc, la phirong phap tham kham rat kinh te nen dirge ung dung rong rai tai cac ca sa v te tu trung irong den dia phirong. Tii nhung nam 1970, sieu am da dirge sir dung tai Viet Nam, ban dau la sieu am loai A, sieu am TM, roi sieu am 2D. Cho den nav cac mav sieu am 2D thoa gian thirc phoi hgp voi sieu am Doppler va Doppler mau, Doppler nang lugng, sieu am ba chieu roi bon chieu, sieu am noi soi ... dirge un^ dung rong rai trong trong tham kham cac tang dac tham chi ca cac tang rong, tirod mau cac tang va cac khoi u, benh lv tim va mach mau... Sieu am phoi hgp voi cac phuong phap chan doan hinh anh khac nhu X-quang so hoa, chup cat lop vi tinh, chup cong hirong tu, chup mach mau so hoa xoa nen... la nhung buac nhav vot trong chuven nganh chan doan hinh anh, chat lirgng chan doan ngav cang cao hem chinh xac hon. xii Loi noi dau Cuon sieu am tong quat nav giup cho cac ban dong nghiep nhung kien thuc chuan va bao quat ve sieu am chan doan o buna, khoang sau phuc mac, sieu am cac tuven va sieu am san phu khoa... Chung toi \in mong dugc su dong gop cua cac dong nghiep de cac tac gia co dieu kien bo sung va hoan thien cac noi dung cua tai lieu duac tot hon va cap nhat hon. PGS.TS P ham M inh T h o ng Pho Giam Doc Benh Yien Bach Mai Truong Khoa Chan Doan Hinh Anh Benh Yien Bach Mai Pho Truong Bo Mon Chan Doan Hinh Anh Dai Hoc Y Ha Noi LOI GIOI THIEU Sieu am la phuong phap chan doan hinh anh y khoa pho bien nhat, gan nhu vo hai doi voi ca the song va co the coi la hieu qua nhat vi no dua lai nhung thong tin quf bau co tinh dinh huong, dinh khu cung nhu thong tin ve cau true cua ton thuong voi chi phi tuong doi thap. Sieu am con co uu the la phuong phap kham xet co the ap dung cho moi bo mav cua co the nguoi tu giai doan dang hinh thanh (thai nhi) cho toi cac mo biet hoa cao nhat, tu tang Ion nhat cho toi phan ben trong cua nhung mach mau rat nho nhu mach vanh tim. Hien nav sieu am la phuong phap chan doan dau tav, khong the thieu cua moi co so chan doan hinh anh. Chuyen nganh chan doan hinh anh trong nuoc hien nav dang rat can nhung giao trinh, nhung tai lieu tham khao cho moi loai hinh dao tao vi chung ta dang rat thieu nhan luc chuven khoa, cang thieu hon so nguoi duoc dao tao co he thong, ngang tam voi cac nuoc trong khu vuc va tren the gioi. Trong boi canh nav, cuon Sieu am tong quat cua PGS.TS Pham Minh Thong va Cong su da tap hop duoc nhung bai viet mang tinh chuyen sau va cap nhat doi mti phuong phap sieu am chan doan toan than. F)av khong chi la giao trinh dao tao chuven khoa ma con la tai lieu tham khao cho cac thav thuoc chuven khoa, sinh vien v khoa nham bo sung va cap nhat kien thuc ve sieu am chan doan. Tac gia cuon sach nav, PGS.TS Pham Minh Thong va nhung cong su la bac sv chan doan hinh anh da va dang phuc \u tai Benh vien Bach Mai, noi co Khoa Chan doan hinh anh phat trien hang dau Viet Nam va cung la noi co benh nhan va benh tat rat phong phu, dugc Bo Y te xep loai benh vien dac biet dau tien trong nuoc; cung cac cong su dang nam giu trong trach khoa chan doan hinh anh o cac benh vien hang dau khac, vi vav toi co lv do de tin rang cuon sach co the cung cap cho nguoi doc khong chi kien thuc co ban ve chan doan sieu am ma con ca nhung kinli nghiem thuc tien qua nhieu nam thuc hanh lam sang benh vien. Tren cuong \ i la Chu tich Hoi Oien quang va Y hoc hat nhan \ iet Nam, toi hoan nghenh tac gia Pham Minh Thong cung cac tac gia cong su va rat vui niung duoc gioi thieu voi Quv dong nghiep trong va ngoai chuven nganh chan doan hinh anh, cac sinh vien v khoa cuon sach nav. Toi tin chac cuon sach se giup ich rat nhieu trong pham \ i thuc hanh va su dung sieu am chan doan, m ot phuong phap con nhieu tiem nang phat trien. GS.TS H o ang Dt'rc Kiet Chu tich Hoi Dien quang va Y hoc hat nhan Yiet Nam - C HUONG 1 DAI CUONG VE SIEU AM CHAN DOAN PG S.TS P ham M inh T hong TINH CHAT VAT LY CUA SIEU AM A. Ban chat song am V / 1 . V . , , Cac moi trUdng dan hoi (khi, long, ran) co the coi nhu moi trUdng lien tuc co cac phan tu lien ket chat che vdi nhau. Luc binh thUdng cac phan tu d trang thai can hang ben. neu tac dong mot lUc len mot phan tu nao do cua moi trUdng thi phan tu nay rdi khoi vi tri can bang ben, do co moi tUdng tac chat che vdi cac phan tu khac trong moi trUdng nen phan tu nay dUdc keo ve vi tri can bang va nang lUOng dUOc truyen cho phan tu ke tiep va de xuat hien hien tUOng tUOng tu. Nhu N •> vay cac phan tu djch chuyen dUdi dang dao dong. Dang dao dong cd hoc co tich chat lap di lap lai, lan truyen trong moi trUdng dan hoi dUdc goi la song dan hoi hay song cd. Ve ban chat song am la song cd hoc do do no tuan theo moi quy luat doi vdi song cd, co the tao ra song am bang cach tac dong mot lUc cd hoc len moi trUdng truyen am. Am thanh la ket qua cua sU lan truyen nang lUdng am trong vat chat dUdi dang mot song tao nen hien tUdng nen va gian lap di lap lai. chuyen dong vat ly han che cua cac phan tu trong moi trUdng vat chat tao nen nhung song co ap lUc giup 2 C h i. Dai cuong ve sieu am chan doan x . ' . / ■> cho am thanh dUdc truyen di. NhCfng bien doi ap ltfc ay difdc bieu hien dtfdi dang song hinh sin (Hinh 1-1) trong do true Y chi ap life, true X chi thdi gian. Khoang cach giiira nhiifng di£m ttfdng ufng tren diTdng cong ap life thdi gian dtfdc goi la btfdc song K. - Thdi gian T de hoan tat mot chu trinh nen va gian dtfdc goi la chu ky. V / - So chu ky trong mot ddn vi thdi gian la tan so f, ddn vi la hertz (Hz). Hinh 1-1. Song am thanh truyen di nhi/ chuoi cac song ap lilt lap di lap lai vdi hien tKOng nen va gian bieu hien dang hinh sin. T la chu ky; f la tan so, butic song X la khoang cach giCm hai diem tuting Cmg tren du^ng cong ap lut thdi gian. Neu bieu thi chu ky T bang giay thi: Ddn vi cua tan so am la hertz (Hz) trong do 1Hz la 1 chu ky trong 1 giay. Tan so cao bieu thi bang kilohertz (KHz), 1 KHz = 1.000 Hz: megahertz (MHz). 1 MHz = 1.000.000 Hz; gigahertz (GHz), 1 GHz = 1.000.000.000 Hz. + Ha am: 0-20 Hz + Am nghe dUdc: 20 Hz - 20 KHz + Sieu am: 20 KHz - 1 GHz. Sieu am chi khac song am thanh nghe diTdc ve tan so. cao gap 500 den 1.000 lan. + Song > 1 GHz la boi am. + Trong Y hoc dung sieu am tan so 1 MHz - 15 MHz. Tinh chat vat ly cua sieu &m 3 - Van tdc truydn cua song am la quang dudng ma song truyen dUdc sau mot ddn vi thcJi gian. Trong moi tnfdng dang htrdng thi toe do truyen am la: C = / V / v ^ v / Trong do a la he so dan hoi; E la suat dan hoi hay con goi la suat Yang; p la mat do (ty trong) cua moi trUdng. - Do dai bitfdc song X (pm) la quang dudng ma song truyen dUdc sau khoang thefi gian bang mot chu ky: A, = C xT = — f Nhu vay, bu6c song chinh la khoang cach ngan nhat gitfa hai diem co dao dong ciing pha. - Ngoai ra, de dac tnrng cho do ldn cua ap li/c am hoc ma cac phan tu trong moi trUcJng nhan dUdc khi chiu tac dong cua nguon phat song am, ngudi ta dua ra dai lUdng P va I. P: la mtic nang ItWng dUdc truyen tir dau do vao moi trUcfng, ddn vi do cua P la W hay mW, thudng thi nang lUdng phat ra tu dau do trong o * sieu am chan doan la tir 1 mW den 10 mW. I: la crfctag do cua song am, bieu thi nang lUdng song am tren mot ddn vi dien tich, ddn vi do la W/cm2 hay mW/cm2. B. Sii lan truyen cua song am ifng dung trong lam sang cua sieu am chu yeu sU dung cac xung nang lUdng ngan truyen vao cd the va lan truyen vao cac mo. Cac song am co the truyen *> V theo phUdng thang goc v6i phUdng cua cac phan tu dao dong trong m oi trtfdng (song ngang) hay trung vdi phUdng dao dong cua cac phan tuf trong moi trUdng (song doc). Trong mot moi trudng nhat dinh thi toe do truyen cua song am la hang dinh, no V / lien quan tdi tan so va budc song. C = fx X / V ^ / 7 v / Toe do truyen am trong cac mo bien doi nhieu tuy thuoc vao tinh chat vat ly cua mo ma song am truyen qua. Toe do lan truyen bi chi phoi chu ygu bdi do khang cua moi trtfdng vdi lire nen (trd khang am). Do khang nay lai phu thuoc vao ty trong cua moi trUdng cung nhu do cung hay do dan hoi cua no. Trong moi trUdng thien nhien, trong khong khi toe do truyen la 350 m/s. Sieu am 4 C h i. Dai cirong ve sieu am chan doan truyen trong khong khi rat kem: do do giOra nguon phat sieu am vii cd the phai co mot moi trudng dan truyen trung gian nhu dau nUOe. Trong cac moi trUdng khac sieu am truyen tot: + Paraftn: l .400 m/s + Nude: l.500 m/s + Thep: 5.000 m/s Trong moi trudng sinh hoc: + Phan mem va md: l.400 m/s + Cd: l.600 m/s + XUdng: 3.600-4.000 m/s + Cac bo phan cd nhieu khi nhu phoi. da day. rudt. sieu am rat khd truyen qua. Tdc do truyen cua song am trong cd the khoang l.540 m/s nen la cd the tinh dUdc do dai cua bude song khi song am truyen vao cd the. + Neu tan so song am la 5 MH/ thi do dai budc song la: C 1540000 mm X = — = ----------------- = 0, j08 ^ 0, j 1 mm f 5000000 + Neu tan so la 2 MH/ thi budc song: A - 0.77 mm + Neu tan so la 7 MH/ thi budc song: A = 0,15 mm ' ' 1 , / / V Cac yeu to anh htfdng den toe do truyen am - Trong moi trUdng dong nhat (A) thi tdc do cua song am la hang dinh. ^ » V A V . 1 , , . ' tan so va do dai cua budc song lien quan tdi tdc do qua cong thuc: CA= fxA A - Co hai yeu to anh hudng tdi tdc do truyen cua song am la : + M at do cua moi trUdng (p) bieu thi bang g/cm2. Mat do bieu thi mUc do gan nhau cua cac phan tu trong moi trUdng. no tang dan tit: Khong khi nude md to chuc dac \Udng + Tinh dan hoi cua moi trUdng (H). No bieu thi kha nang trd lai \ i tri \ a hinh dang ban dau sau khi nen ha\ keo. Tinh dan hoi tha\ doi theo nhiet do va ap suat. Nhu va\ tdc do truyen am va bu«\ song cung phu thuoc vao nhiet do va ap suat. Tuv nhien no khoni: anh hudng nhieu den chan doan \i trong moi trudng tham kham thi nhiet do va ap suat tha\ doi rat it. Khi song am truyen tir moi trudne A san^ moi trudns B thi toe do cua Tinh chat vat ty cua sieu am 5 no se bi thay doi. Vi tan so cua song am la hang djnh (phu thuix- vao tan so cua dau do) nen chieu dai budc song thay doi theo cong thufc: CB= fx X B - Nhifng cung can lifu y: cac thay doi toe do song am tu moi trudng nay sang moi trtfdng khac rat it. trir tnrdng hop co sir khac biet rat ldn ■> « / giffa hai moi tnrdng nhu phoi va xiTOng. Ngudi ta van tinh toe do truyen cua song am trong moi trudng sinh hoc la 1.540 m/s. C. Trd khang am v£ cac djnh luat truyen am 1. Trd khang am cua moi trtfcfng't Trd khang am cua moi trudng dUOc hieu la do doi hay do vang cua song am trong moi trudng. Z = pxC + Z: Trd khang am.o + p: Mat do moi trudng (don vi: kg/m ). + C: Toe do truyen cua song am trong moi trtfdng (m/s). Trd khang am cua moi trudng noi len stfc can cua moi trudng doi vdi stf V • 9 / / N V truyen am, no cao 0 nhung to chtfc dac va thap doi vdi nude va phan mem, khong khi. Trd khang am cua mot so to chtfc: + Khi co Z = 0,0004 + Nude cd Z = l,4 8 + Xuong cd Z = 3,65 den 7,09 Ngirdi ta goi mat phang phan chia hai moi trudng cd trd khang am Z khac nhau la mat phan cach. 2. Si/ phan xa, khuc xa, tan xa Song am dUdc truyen di theo nhufng tia goi la tia am. nghien cuu thuc nghiem / / 9 cho thay song am cung cd the hi phan xa. khuc xa. tan xa nhu tia anh sang, a. Si/ phan xa (phan hoi) Khi song am truyen trong moi trudng dong nh^t va dang hudng no se V 9 truven theo phuong thang, khi gap mat phan each du ldn (kich thudc cd dudng kinh cp > budc song X) giOfa hai moi trudng cd trd khang am khac nhau. tia am se tuan theo dinh luat phan xa va khuc xa. Mot phan niing lUOng song am se phan xa trd lai. mot phan song am se truyOn ticp vao moi trudng thu hai. 6 C h i. Oai cirong v£ sieu am chan doan Mtfc do phan xa phu thuoc vao mtfc do khac nhau ve trd khang am cua hai moi trtfdng. Neu hai moi trtfdng co trd khang am bang nhau x ltfdng tdi cua chum song am. no dtfdc xac dinh bang he so phan hoi R. Nlu chum song tdi vuong goc vdi mat phan cach thi ltfdng nang ltfdng phan hoi dtfdc tinh theo cong thuc: R 17 7 ' ( z : - z , r Trong do Z2 va Zi la do trd khang am cua hai moi trtfdng. N£u chum song am khong di vuong goc vdi mat phan cach. song phan xa se di xa dau do va dau do khong thu dtfdc song phan xa. b. Khuc xa Khi chum song am khong di vuong goc vdi mat phan cach thi no se bj •» / doi htfdng va tiep tuc di. do la hien ttfdng khuc xa va tuan theo luat Snell: sin 9' _ Cj sinG* C; Trong do la 01 goc cua song tdi vdi mat phan cach. 02 la goc khuc xa: Ci va C2 la toe do song am truyen trong hai moi trtfdng tao nen mat phan cach. Hien ttfcfng khuc xa quan trong vi no la mot trong nhtfng nguyen nhan gay hien thi sai lech hinh anh sieu am. Khi dau do nhan song phan am. no tfdc dinh nhtf vat nam tren cung mot hudng co dinh nhin tu dau do. ' / ”> V neu song bi khuc xa thi phan am nhan dtfdc va bieu thi bang hinh anh thuc ra tu do sau va vi tri khac. Chinh vi vay khi thuc hanh lam sang, khi nghi ngd thi phai tang goc quet de chum song tdi vuong goc vdi vat lam mat hien ttfdng khuc xa va lam giam anh gia. c. Tan xa Mot hien tUdng khac quan trong trong tao hinh bang sieu am la hien tUdng tan \a cua tia sieu am khi gap cac cau true nho trong moi trtfdns hoac vdi be mat khong dong deu. Khi do chum song sieu am se bi phan \a truyen di moi htfdng igoi la tan xai. chi mot phan rat nho song am phan \a ve dtfvV dau do. Tinh c h it vat ly cua si£u &m 7 Hien ttfdng nay phu thuoc vao chieu dai btfdc song cua sieu am (Hinh 1- 2): - Neu kich thtf6c cua vat nho hon chieu dai btfdc song sieu am thi tan xa theo moi htfdng. - Neu kich thtf6c cua vat gan bang chieu dai btfdc song sieu am thi tan xa theo htfdng trtfde sau. - Neu kich thtf6c cua vat ldn hon chieu dai btfdc song sieu am thi tan ✓ xa theo htfdng nhat dinh. Hinh 1-2. Hien tutfng tan xa cua song am. a. Kich thudc cua vat nho hdn budc song am, tan xa di moi hi/dng. b. Kich thudc cua vat gan b5ng budc song: tan xa theo hifdng trudc sau. c. Kich thudc cua vat ldn hdn budc song: tan xa theo hudng nhat dinh. Vai tro cua hien tiftng tan xa trong chan doan sieu am - Htfdng cua dau do khong anh htfdng den chat ltfdng cua song am phan hoi ve thu dtfdc vi song phan hoi nay phat ra theo moi htfdng do hien ttfdng phan xa. - Tan xa tang len khi tang tan so cua song sieu am, nen cac dau do din so cao se phat hien dtfdc cac cau true nho trong to chtfc. - Tan xa dac thu vdi cau true cua cac to chtfc nen cho phep nghien ctfu / 7 v V cau true cac to chtfc khac nhau. Nhu nghien ctfu sir dong deu cua nhu mo cac tang gan, lach... 3. Stf hap thu cua to chuTc va stf suy giam nang lifting cua song am Khi song am truyen vao moi tnrdng no tac dong d6n moi tnrdng va nang lifting ctia chum song am bj giam di do hai nguyen nhan chinh la: * 9 - Hien trfcfng bien doi htfdng ctia song am: + Khuc xa. 8 C h i. Oai cirong v£ si2u am chan doan + Phan xa. + Tan xa. * - Hap thu Hap thu la hien ttfdng phtfc tap. gay ra hien doi nang ltfdng cd hex: thanh nhiet nang do sir co sat. Co the danh gia dtfdc mtfc do suy giam cua crfdng do chum song am. - Ctfdng do ctia song am dtfdc tinh theo cong thric: + P la bien do cua ap life nen cua chum scSng am. + p la mat do cua moi tnrdng. + C la toe do cua song am trong moi tnrdng. + I la ctfdng do cua song am. - Ctfdng do cua song am dtfdc tinh bang w/cm2, ctfdng do chi kha nang phan bo nang ltfdng trong khong gian. la ty so gitfa cong suat vdi do rong cua vung (dien tich) phan bo. I (w/cm2) = Cong suat (w)/ Vung (cm2). - CiTdng do song am trong y te trong khoang tir 10 mw/crrf den 10 w/cm2. vdi ciTdng do nhtf vay khong gay cac anh htfdng sinh hoc. - Stf suy giam nang ltfdng song am theo cong thu’c: (Hinh 1 -3). Hinh 1-3. 0o thi suy giam cub’ng do am khi vao sau + Ix la ctfdng do song am d khoang cach \ so vdi dau do. Ky thuat cua phirong phap tao hinh bdng sieu am 9 + Io la cirdng do luc dau. + e la hang so logarit Nepe (J. Napier). ✓ / + (i la he so hap thu. + x la do sau cua vung khao sat. MuTc do suy giam nang lifting nay thUdng dUdc tinh bang (dB Decibel) hay dB/cm. Ddn vj do nay dUdc hieu nhu sau: d vi tri Xi bien do cua song ap luc am la Pi; d vi tri X2 thi bien do cua song la P2. Di tu Xi den X2 thi bien do am da suy giam di D (dB), dUdc tinh theo cong thufc: D [dB] = 20 log / \ 7 V Doi vdi mo mem co the ap dung cong thufc gan dung sau: Do suy giam D [dB] = f [MHz] . d [cm] . (i (f la tan so, d la khoang cach giufa hai vi tri; ^ la he so hap thu). Tu cong thufc tren ta thay sir suy giam nay cung phu thuoc nhieu vao tan so, gan nhu ty le thuan vdi tan so. Su phu thuoc nay la mot trong nhflng han che cua sieu am chan doan, vi tan so cang cao thi do suy giam cang cao do do kha nang dam xuyen vao sau cang kern. ✓ V Chinh vi vay tren cac may sieu am deu co bo phan khech dai bu theo chieu sau: DGC (Depth Gain Control) hay con goi vdi ten khac la TGC (Time Gain Compression). Nang lUdng sieu am cang vao sau cang giam, khi vao sau tdi 20 cm vdi dau do tan so 3,5 MHz va he so hap thu (|i = 1), theo cong thuc tren thi ta co D = 70 dB. Suy giam trong to chufc phan mem tir 0,3 dB/em/MHz. Song am truyen vao xUdng se suy giam rat nhanh: 10 dB/cm/KHz; va d phdi la 20 dB/cm/KHz. Chinh vi vay song sieu am kho truyen di dUdc qua xUdng o va phdi. Khi song am di qua mo, suy giam nang lUdng cua song am la y£u t6 quan trong trong ufng dung lam sang, do no anh hudng den do sau nen anh hiidng ' a 7 den cac thong tin thu dUdc khi tham kham cac ton thUdng trong sau. II. KY TH U A T CUA PH U O N G PHAP TAO HINH BANG SIEU Am A. Nguyen ly tao anh V N T Dau do khi dUdc kich thich bdi xung dien vdi chieu dai va cUdng do co the thay 10 C h i. Dai cirong ve sieu am chan doan ddi dUdc, thi no phat ra song sieu am lan truyen theo hudng cua dau do vao moi trudng vdi van tdc xac djnh bdi dac tinh cua moi trudng do (mat do va dp dan hdi). Song am se gap cac mat phan cach tren dudng di va tao ra cac phan xa va tan xa am quay vk dau do. dau do se thu nhan lai cac tin hieu phan xa nay. Khoang thdi gian m§t cho song am di tdi mat phan cach roi quay ve dau do dUdc xac djnh theo cong thuc: d = C x -2 + d: khoang thdi gian tir dau do den mat phan each. + C: van tdc song am trong moi trudng. + t: khoang thdi gian cho song am di tdi mat phan cach va quay ve. Do ldn va bien do cua song phan hoi phu thuoc vao do ldn va bien do cua song phat di, goc tdi cua song am, trd khang am cua moi trudng. Dau do se bien tin hieu am phan hdi ve thanh tin hieu dien thong qua hieu ung ap dien. Tin hieu dien nay mang hai thong tin chinh la: - Thong tin ve ctfcfng do va bien do. thong tin nay phan anh tinh chat am hoc cua moi trudng. - Thong tin ve vi tri cua mat phan cach tao ra tin hieu thong qua trung gian la thdi gian do dUdc tu khi phat song am den khi song am quay ve dau do. Cac thong tin nay dude xuf ly va hien thi thanh hinh anh tren man hinh. Hieu iftig ap dien (Hinh 1-4) do hai nha bac hoc Jacques va Pierre Curie tim ra vao nam 1880, hieu Ung nay thay tren tinh the thach anh va sau do thSy nhi^u loai gdm sU tu nhien cung cd hieu Ung nay. ■> Hieu Ung ap dien dUdc hieu nhu sau: Cac vat lieu mang tinh ap dien cd kha nang thay ddi hinh the dudi tac dung cua mot dien trudng. Chung cung mang dac tinh sinh ra mot dien the khi bi ep lai. Khi thay ddi phan cUc dien the ap vao tinh the vat lieu ap dien (thach anh) thi do day cua tinh the thay ddi, ket qua la phat ra song ap luc cd hex’ truyen vao moi trudng. Hieu Ung ap dien cung sinh ra nhun^ dien the nho khi phan am trd lai tac dong vao d^u do. B. Cac hinh thtfc hien thi hinh anh sieu am 1. Sieu am kieu A (Amplitude Mode) a. Nguyen ly Dau do phat sieu am gian doan. chum sieu am khi xuyen qua cd the se gap nhurng bo phan cd trd khane am thanh khac nhau. va se cho nhun^ Ky thuat cua phuong phap tao hinh bing sieu am 11 am thanh phan xa trd ve tac dung len dau do sieu am, tao thanh nhung tin hieu dien, nhurng tin hieu nay dUdc khuyech dai va dUdc truyen vao man *> hien song cua may dao dong ky, bieu hien thanh nhiirng hinh xung nhon 9 1 1 / nho len khoi dtfdng dang dien. NgUdi ta goi kieu nay la kieu A, do lay churdau cua amplification. (Hinh l -5, 6, 7A). » * ur\j Hinh 1-4. Hieu utig ap dien. a. Tinh the cl tu1 the nghi, khong co khac nhau ve dien the. b. Ep cd hoc, xuat hien dong dien. Tinh the dutic noi vdi nguon dien (c, d, 3). c. Mach chite dong: khong co hien tinging gi. d. Dong dong dien: thay doi chieu day tinh the. d. Bong dong xoay chieu: tinh the thay doi chieu day hinh sin va phat song am (tinh the rung len). Bien do cua cac xung ty le vdi cUdng do cua cac am vang. Con vi tri cua cac xung danh dau vi tri cua cac bo phan da phan xa am vang trd ve. Tren man hien song co mot thang do chia do: moi vach nho la 2 mm. va moi vach to la 1 cm. Nhd thang do ay chung ta co the doc ngay khoang cach gitifa cac xung vdi nhau va vdi xung danh dau dau sieu am. b. Ap dung Chan doan sieu am kieu A ngay nay it dung mot minh. ma thUdng phoi hdp vdi kieu B. No dUdc ap dung trong mot so chuyen khoa: 12 C h i. Dai ciwng ve sieu am chan doan - Khoa san: Do dudng kmh lUdng dinh cua thai. do khung chau cua san phu. - Khoa mat: Do dudng kmh nhan cau. phat hien hong vong mac. - Khoa than kinh: Thudng ngudi ta dung kieu A mot minh de lam am vang nao do. _ A A M Hinh 1-5. Hinh 1-6. • A A • X 2 Sieu am kieu A de do di lech during giifa cua nao. 0 2 \ 4 6 8 10 12 14 16 Sieu am kieu A: Gian nao that III va di lech dudng gii/a sang phai. Sieu am kieu B (Brightness Mode) (Hinh 1-7 ) Con goi la am vang do cat ldp. am vang dd hai chi^u. Goi la ki^u B do la\ chu dau cua tu Brightness. Tiong kieu nay cac tin hieu dtfcfc chuyen thanh diem sang ma do sang t\ le Ky thuat cua phirong phap tao hinh bang sieu am 13 vdi ciTdng do tin hieu. Diem mau chot cua hinh anh hoc sieu am hien nay la hien thj dtfdi thang xam theo thdi gian thtfc tufc thi. Kieu B vdi cac tin hieu phan xa co hien do khac nhau dupe the hien qua cudng do hay mUc do sang. Khi hinh sieu am hien tren man hinh co nen den. cac tin hieu cudng do manh hien len mau ✓ 9 trang, khong co tin hieu the hien mau den. con cac tin hieu vdi cUdng dd 9 / sang trung gian the hien qua cac sac xam (thang xam). 3. Sieu am kieu TM (Time Motion Mode) (Hinh 1-7) 9 9 9 9 n 9 Dung de hien thj chuyen dong cua cac vat the theo thdi gian hang each the 9 ~ / / / hien hinh kieu B theo dien hien thdi gian vdi cac tdc do quet khac nhau. Ket qua la tren man hinh ta se thay: neu mat phan hdi am dung yen thi tren man ^ 9 V 9 / ^ v 9 hinh se hieu thi hang dudng thang. neu mat phan hdi am di chuyen (vat di 9 V 9 chuyen) thi tren man hinh se ve len do thi di chuyen cua vat. 9 9 Tren man hinh hien thi hien do ehuyen dong cua mat phan each hieu thj theo true tung, thdi gian theo true hoanh nen cd the tinh toan dupe van tdc cua mat phan hdi. * 9 9 9 9 ling dung chinh cua sieu am kieu TM la danh gia cac chuyen dong cua cac van tim. hudng tim, vach tim. Sieu am kieu TM cung dupe dung trong danh gia di dong nho cua thanh mach tir dd danh gia tinh dan hdi cua thanh mach trong henh xP vura dong mach. Sieu am kieu B, TM deu la sieu am 1 chieu vi chi phat mot tia song sieu am va chi thu thong tin tren mot dudng thang tao anh. 4. Hinh tinh va hinh dong 9 9 9 9 N Ccf scl cua viec the hien hinh anh sieu am hai chieu la dua vao sieu am 9 v ✓ ✓ kieu B va dupe dung trong hau het cac may sieu am tu trudc den nay. 9 9 9 - V Theo each the hien cua kieu B thi tuong xung vdi moi vj tri dau do tren cd the va moi hudng cua chum phat song nhat dinh thi tren man hinh cd mot dudng tao anh phan anh cac mat phan hdi dupe tao ra hdi cau true cua cP the tren dudng di cua song am. Neu tong hefp nhieu dtfdng tao anh tren cung mot mat phang thi ta se dtfdc hinh anh sieu am phan anh cac ciu true giai — , 9 9 f phau cua cP the tren mot mat phang. Vao nhung nam 60. de thuc hien dupe nhu tren. ngudi ta gan dau dd phat song am vao mot true khuvu cd khdp noi 1 9 9 V V x cd the dieu khien dUPc dau dd, thuc hien quet hang tay (sieu am cat ldp quet hanu tay). 14 C h i. Dai circmq ve sieu am chan doan Kinh 1-7. Cac kieu sieu am. A. Sieu am kieu A. B. Sieu am kieu 8. TR. Sieu am kieu thdi gian thuc. TM. Sieu am kieu TM. / V _ 1 ✓ Do han che ve ky thuat, thdi gian quet keo dai de co mot ldp cat ngang cd the, hinh anh nhan diTdc chi la hinh fmh nen he thong nay dtfdc goi la quet hinh tinh va no it dtfdc suf dung. ’ / *» / v i ' t * De thay dtfdc chuyen dong ttfc thi cua cac cau true trong cd the nhat la tim thi toe do hinh anh phai nhanh, thtfdng khoang 25 hinh/giay. Cuoi nhtfng nam 70, the he sieu am mdi ra ddi cho hinh anh dong goi la sieu am thdt gian thtfc (Real time scanner). Toe do tao hinh nhanh nhd ky thuat quet chum song am nhanh va kha nang xuf ly thong tin nhanh cua may vi tinh. Co hai cach quet la: - Quet dien tiif (Electronic scanning): Cac tia sieu am dtfdc quet nhd ^ I I • A / * V ^ / / / dieu khien dong m d cac nguon nuoi cac tinh the sap xep ke can nhau theo trinh tir thdi gian tir dau no den diu kia cua d^u do, moi lan quet nhiT vay ta thu diTdc mot frame anh. quet nhieu lan trong mot giay (toi Thiet bj ghi hinh bing sieu am 15 thieu 4-30 anh) ta se dtfdc hinh dong thdi gian thuc. - Quet cd h9C (Mechanical scanning): Tia sieu am dtfdc quet khi cac tinh th§ g6m dtfdc quay tron theo mot true hay dtfdc lac theo kieu dao ✓ dong con lac. Nhtfdc diem cua may ghi hinh dong la dien khao sat bi han che, khong cho hinh anh tong quat toan the. Ky thuat hinh dong bi han che do ba yeu to sau: - So hinh trong mot giay (Frame rate-FR). - So dtfdng quet cho mot hinh (Line density-N). - Do sau cua vung khao sat (d). Ba yeu to nay lien quan chat che nhau theo cong thufc: ! N x t = 2N x — FR C Trong do 1/FR la thdi gian tao mot hinh; t la thdi gian tao mot dtfdng hinh ^ ^ \ V V v / ") / (thdi gian song sieu am di tdi dich roi quay ve dau dd). Nhtf vay neu khao sat rong thi mat do dtfdng tao anh phai ldn cho nen lam tang thdi gian tao mot anh, chinh vi vay ma han che tdc do tao hinh cua may (so hinh trong mot giay se thap). V / ■) Trong nhtfng nam gan day, vdi cac may the he mflfi co the vuTa cho hinh dong va vufa tham kham dtfdc tri/cfng rong, goi la Real Time EFOV (Expended fiel of view - sieu am thdi gian thtfc vdi trtfdng nhin md rong). De cd khao sat rong thi vtfa di chuyen dau dd theo thiet dien cat ngang cd V *> V 9 the, may vtfa ghi nhan hinh anh, hinh anh dtfdc tong hdp lien tuc tir cac goc quet rieng biet tfng vdi cac vi tri cua dau dd. Ket qua nhan dtfdc la mot hinh ** * v v ~ / 9 v tong quat nhtfng dong thdi van gitf dtfdc tinh dong cua hinh anh. Ky thuat nay stf dung thuat toan Fuzzy-Logic vdi xtf ly ctfc nhanh cua may vi tinh va bo vi xuf ly truyen thong da phtfdng tien (MVP: Multimedia Video Processor). III. THIET BI GHI HINH BANG SIEU Am A. Scf do cau tao chung cua may sieu am ' ty 7 \ Cau tao chung cua mot may sieu am chan doan bao gom: bo phan phat va thu song am (dau dd), bo phan dieu khien va xtf ly hinh anh, man hinh hi£n thi va bo phan ltfu trtf. (Hinh 1-8). B. Baudd / 9 V 1. Cau tao cua dau do N N ✓ V ^ 9 Dau dd chinh la dung cu de chuyen nang ltfdng dien thanh nang ltfdng cd hoc 16 C hi. Dai cirong ve sieu am chan doan va ngtfpc lai chuyen nang lifpng cd hoc thanh nang lupng dien di/a \a«> hieu Ung ap dien. Dau doDi§u khien va Man hinh xu1 ly hinh anh hien thi I LlTu tru’ Hinh 1-8. Cau tao chung cua may sieu am. Cau tao cua dau do bao gdm ba thanh phan chinh la: - Tinh the gdm ap dien. - Bo phan hap thu. - Ldp hoc dan am. Tinh the gom ap dien: Gdm ap dien la loai P/.T (Plomb Ziconat Titanat) cd tinh ap dien cao. Cac tinh the gdm dac cat mong va xep sap canh nhau theo nhieu each khac nhau tuy theo ttfng loai dau do. Cac tinh the gdm nay khong nhay cam vdi do am. rat chac chan nhtfng rat nhay cam vdi nhiet do (nen khong the khuf trung dau dd bang nhiet do). Mat trtfdc va mat sau cua tinh the gom dupe hoc bdi ldp kim loai monsz iriup lien ket cac mieng gdm ' a cho phep truven dong dien \ ao mieng 26m cuniZ nhu thu dong dien ve khi dau do hoat dong. X v ' x * V / V Be day tinh the gom quyet dinh tan so cua dau dd: A l = m — (m = 1.2. 3...) v — v , 1 la so ngu\en lan /_/2: thtfdng m dtfdc chon bang 1. nhtf vav tinh the cani: mong. budc song cang ngan thi tan so cang ldn. Neu tinh the gom da\ 1 mm thi dau do cd tan so 2 MH/. ( 1 V X , Tinh the da\ 2 mm thi dau do tan so 4 MH/. Thiet bj ghi hinh bang sieu am 17 7 1 \ Ngay nay vdi sir phat trien cua cong nghe vat lieu tong hdp, cac dau do s / / \ / / N khong chi co mot tan so ma co dai tif 2 den 8 tan so. Ky nghe che tao dau do cung tinh xao hdn, vi du nhtf dau do o hinh vong cau tao ttf rat nhieu cac 7 / v ^ ^ y tinh the kich thtfdc ttf 100-200 |im sau do lap day cac vet cat bang cac vat lieu trd khang thap de giam trd khang chung cua dau do (Hinh 1 -9). Hinh 1-9. Dau do hinh vong vdi cac tinh the gom xep hinh vong va co kich thudc cut nho tu1 100-200 urn. Bo phan chan phia sau / V ' 7 / / v Bo phan chan nam phia sau tinh the gom cau tao bang hot min Tungsten hay Chi, no co 4 tac dung: 9 / / / - Lam cho cac tinh the gom dtfdc co dinh vtfng chac. O x S' v - Lam ngufng rung cac tinh the gom sau khi noi nguon dien, lam cho o s ✓ cac tinh the gom rung ngan thanh cac xung, tranh hieu tfng rung chuong. / i - Hap thu cac song am di ra sau de khong co cac tap am. - Thay doi bang dan truyen (la dai tan so nam gitfa hai dau cua tan so cong htfdng). Bo phan chan se lam tang do rong cua bang dan nhtfng lam thu hep hieu suat cua dau do. Bo phan boc khong can am phia trtfdc Ldp nay nam d phia trtfdc cac tinh the gom. ngan cach cac tinh the gdm vdi da benh nhan, no cd tac dung dan truyen song am. V V V qua nhieu song am ve dau dd. Cd the cd ldp thau kinh hoi tu am nam trtfdc cac tin song am. (Hinh 1-10). 2. Hoat dong ciia dau do tranlrhien ttfdng phan xa the* gdm de hdi tu chum 18 C h i. Dai cirong ve sieu am chain doan b e d Hinh 1-10. Sd do dau do co mot tinh the gom. a. Ldp boc dan am: b. Thau kinh hoi tu am; c. Mieng gom ap dien; d. Bo phan chan phia sau; 3. Vo boc: e. Cap dien. Dau do phat nang ltfdng am theo mot htfdng nhat dinh, song am co cac tinh chat: - Htfdng cua song am di thang ra trtfdc va vuong goc vdi mat trtfdc cua dau do. - Tan so cua song am ttf 1,5 MH/. den 12 M H/ trong chan doan. - Phan ho song am trong khong gian hay con goi la trtfdng am. phan bo nay chia thanh hai vung (Hinh 1- 11): + Vung gan dau do (vung Fresnel) Tai vung nay chum song am dtfdc truyen di theo phtfdng gan nhu song song, dtfdc goi la trtfdng gan hay goi la vung Fresnel. Chieu dai \ ung Fresnel: L = — =4/. Trong do r la ban kinh tinh the gom cua dau do. I) la kich thtfdc dau do. Nhtf vay chieu dai cua trtfdng Fresnel co the thay doi neu thay doi kich thtfdc cac tinh the gom va thay doi btfdc song. Tinh the gom cang ldn. btfdc song cang nho thi vung Fresnel cang dai. Chieu rong cua vung Fresnel bang kich thtfdc cua dau do. no giam doi vdi dau do co trtfdng nhin hep. + \ ung xa dau do (vung Fraunhoter) \ ung nay song am loe ra va khong cho phep phat hien cac ton thtfdng nho. Goc loe cua vung \a co the tinh dtfdc theo cong thtfc 0.69/. a =Dha\ Sina = 1.22/. D Thiet bj ghi hinh blng sieu am 19 Kinh 1-11. Dang chum song am dude phat ra tu1 dau do vdi cac vung xa va gan. a la vung gan (vung Fresnel); b la vung xa (vung Fraunhoter). *» V - De lam tang chieu dai vung Fresnel, vung cho phep nghien ctfu dtfdc cac cau true nho, thi phai lam giam goc loe bang cach hoi tu chum song am (Hinh 1-12). Co the dung phtfdng phap hoi tu cd hoc (thau ^ V 1 / / kinh am hoc hay dau do co cac tinh the gom xep lom hoi tu) hay hoi tu dien tuf, hoi tu cd hoc it dtfdc stf dung. Hinh 1 -12. Hoi tu cua dau do. 1.Bau do khong hoi tu. 2. Bau do hoi tu cd hoc d xa. 3. Bau do hoi tu cd hoc d gan. 4. Hoi tu dien tu1 20 C h i. Dai cirong ve sieu am chan doan Do phan giai cua dau do Do phan giai la khoang cach nho nhat giilifa hai diem (tinh hang mm) tren hinh sieu am phan biet dtfdc. no bao gom phan giai doc va phan giai ngang. a. Phan giai doc: la kha nang phan biet khoang each nho nhat gitfa hai vat co the nhin thay de gan nhau va theo true cua chum song am. no dtfdc tinh ttf stfdn hai xung phan hoi ttf hai vat nho dtfng canh nhau. Phan giai doc lien quan den btfdc song A. chinh btfdc song gidi han mtfc do phan giai cua dau do vi: F Neu F = 3.5 KHz thi /. = 0.44 mm. Cac dau do co tan so cao se co do phan giai doc tot hdn dau do tan so thap. Phan giai theo true (doc) cung phu thuoc vao thdi gian phat xung. thdi gian cang ngan do phan giai cang cao. Vdi cac dau do tan so 3.5 MHz thi co do phan giai khoang 1 mm (Hinh 1-13). b Hinh 1-13. Do phan giai doc phu thuoc vao chieu dai budc song va thdi gian phat xung. a. Xung ngan. tan so cao: phan giai tot. b. Xung dai tan so thap: phan giai kern, khong phan biet dup'c hai diem. b. Phan giai ngang: ha\ kha nang phan biet hai diem nam vuong goc vdi true cua song am di qua. Thiet bj ghi hinh bang sieu am 21 Do phan giai ngang phu thuoc vao do rong cua song am. do rong nay v / V 9 V ' s • \ phu thuoc vao: tan so dau do, hinh the dau do, gom ap dien va phu thuoc vao mufc do hoi tu cung nhu khoang cach gitfa dau do va vat quan sat. (Hinh 1-14). So lifting cac dtfdng song am Trong sieu am thdi gian thtfc, phan giai ngang con bj anh htfdng bdi so dudng phat song am, hay so dtfdng tren trtfdng nhin nhat djnh. / \ *> ^ / V Cac dtfdng nay song song nhau neu dau do thang va dang toa ra neu dau do cong. Cac dtfcfng nay day hdn d vung gan dau do va cach xa nhau hdn khi vao sau. So ltfdng cac dtfdng song am lien quan den so ltfdng cac hinh dtfdc tao ra trong mot ddn vi thdi gian. Tot nhat la co dtfdc nhieu hinh trong « mot giay vdi do phan giai khong gian cao nhat. ■ i / w* _— *w. *t _ -jtk r W 1 2 1 \ Hinh 1-14. Bo phan giai ngang phu thuoc vao chieu rong cua chum song am. 1. Truting song am rong khong co hoi tu. 2,3. Trutfng song am hep co hoi tu. Tuy nhien tich soRxDxN la mot hang so. (R la so hinh trong mot giay; N la so dtfdng; D la do sau tham kham). Nhtf vay la co stf thoa hiep gitfa do sau ctia trtfdng nhin, so ltfdng dtfdng quet va so ltfdng hinh anh trong mot ddn vi thdi gian tinh bang giay. Cac may thdi gian thtfc co the quet tdi 250 dtfdng tren 10 cm va cho 30 hinh trong mot giay. 22 C h i. Dai cirong ve sieu am chan doan 4. Cac loai dau do a. Dau do thang (Linear Array) Dau do dtfdc cau tao tCr day "n" cac tinh the don gom ap dien. song mcu am dtfdc tao ra tir "m“ don tinh the dirng canh nhau va dtfdc quet bang cach tai tinh the dtfng dau nhom va bat them mot tinh the dung ke tinh the cuoi cung cua nhom. nhu vay chum song sieu am se dtfdc dich chuven di mot khoang hang chieu day cua tinh the gom. Bang cach thay doi do rong cua nhom tinh the ngtfdi ta co the tang so dtfdng tao anh len gap doi: dau tien phat va thu tin hieu bdi nhom "m" tinh the. sau do bat them mot tinh the ke ben tinh the cuoi cung cua nhom va thu ma khong tat tinh the dau tien de tao thanh "m + 1" tinh the sau do nidi tat tinh the dau tien va bat tiep tinh the ke theo. Nhu va\ chum song am phat di tir nhom "m +l" tinh the se dich di so vdi chum song am co do rong "m" tinh the mot khoang cach bang 1/2 chieu day cua tinh the. Tien hanh nhu va\ ta co so dtfdng quet tang len gap doi tuy nhien so hinh (tdc do quet hinh) cung bi giam di mot ntfa. Mot dac diem ntfa cua dau do thang la co the thay doi vj tri cua diem hoi tu bang cach thay doi do rong cua nhom (so tinh the), nhom cang ldn thi diem hoi tu cang nam sau. Dau do thang co the lam viec d che do co nhieu diem hoi tu. co the tu 2 den 4 hoi tu cung mot luc. tu\ nhien khi tang nhieu hoi tu thi phai tang so dtfdng quet va nhu vay thi toe do quet hinh (so hinh trong mot giay) se giam di 9 ✓ den ctfa so phat am, dung md-to de lam quay vong gan cac tinh the / 9 s v v -w 9 gdm ap dien. Cac tinh the gdm nam trong hop chtfa dau dan am va de truyen nhiet (Hinh l - 15). Hinh 1 -15. Hinh dau do cd hoc quay. 3 mieng gdm ap dien dtfdc g^n vao mot vong quay dtfdc nhd mo-td. song am phat ra se co dang hinh re quat. X V AAA - Dau do cd hoc mieng gom lac 24 C h i. Dai cuong ve sieu am chan doan Mieng gom dtfpc gan vao mot nam cham. no se dtfpc lac nho xung dien phat ra nhd cuon day. nhtf vay se cho chum song am dang re quat (Hinh 1-16). - Dau do cd hoc kinh am hoc lac Mieng gdm ap dien cd djnh trtfdc gUOng am hoc lac. loai nay hau nhu khong con dtfpc stf dung. - Dau do cd hoc vanh khuyen (Annular Array) Cac mieng gdm dtfpc xep thanh cac vong dong tarn kich thtfdc khac nhau (tdi da 10 vong). cac vong tinh the se dtfpc lac nhd mo-to (Hinh 1-17). Dau dd nav cd nhieu tfu the hon han cac dau dd cO hoc khac: + Be mat tiep xuc nhd. + Do md ldn. + Nhieu vung hoi tu khac nhau. + Gia thanh khong dat. 2 Hinh 1-16. Hinh dau do co hoc lac. 1. Cuon day tao tu'truing. 2. Mieng gom gan vao nam cham vinh cuu. Tu\ nhien no la dau do co hoc nen do ben khong cao va chuyen mixie cham. No dtfdc tfng dung trong sieu am tim. bung tong quat. san phu khoa: dau do qua am dao. dau do trtfc tran^. Thiet bj ghi hinh bang sieu am 2 5 zf Hinh 1-17. Hinh cau true tinh the va trutfng am cua dau do cd hoc vanh khuyen. 1 ,2 ,3 ,4 la vung hoi tu dai hdn. C. Bieu khien, xtf ly tru’dc hinh anh (preprocessing) va cac phan mem utig dung * 1. Khuech dai - Gain Tinh hieu thu ve tir dau do trtfdc khi chuyen doi thanh hinh anh deu phai dupe xtf ly. mot btfdc quan trong la khuech dai tin hieu. Do tin hieu thu ve co bien do qua nho nen can khuech dai, he so khuech dai tinh bang 20 Log ty / / / v so gitfa bien do sau khi khuech dai va bien do trtfdc khi khuech dai. tinh bang dB. Gain = 20Log IL v u >/ IdBl Uj: Bien do trtfdc khi khuech dai. L’l>: Bien do saO khi khuech dai. 2. Khuech dai bu truf theo chieu sau: (DGC - Depth GainCompression hay TGC - Time Gain Compression) 26 C h i. Dai cirong ve sieu am chan doan Khi song am truyen vao moi trtfdng se bj hap thu lai mot phan nen cang \ao sau nang ltfpng cua song am cang giam va cac song phan hoi ve cd bien Jo cang thap. chinh vi \ a\ can phai bu lai nang lifting da mat. I >GC has TGC chinh la sir khuech Jai theo thdi gian. song am phan hdi ve tir mat phan cach d xa se JtfOc khuech Jai nhieu hon song phan hdi tir mat phan cach d gan. 3. Khuich dai tang bd (EE - Edge Enhancement) KhuOch Jai tang bd cd tac dung tang do phan giai doc theo phirong truyen cua song am bang cach tang dd vi phan cua tin hieu. khi tang khuech Jai tang bd hinh sieu am cd hat min hon. cac be mat vuong goc vdi phirong truyen ctia song am dtfdc ve ra rd net hon nen phep xtf ly nay dtfdc goi la khuech Jai tang bd. 4. Dai dong (DR - Dynamic Range) Tin hieu thu ve nam trong khoang tin hieu rat rong: cac mat phan cach mo mem/khdng khi cho tin hieu phan hdi ldn nhat nam trong khoang 1-10 V trong khi nhu md cac co quan cho tin hieu phan hdi ve rat thap trong khoang 10 pV-10 mV. Nhtf vay toan bd Jai tin hieu thu dtfpc nam trong khoang 10pV-10 V. Thay Jdi Jo rong cua tin hieu Je Jap dng do tiftfng phan cua hinh anh sieu am ctfc Jai. Cac gia tri I)R thap can thiet khi can nhin rd cac Jirdng bao nen hay Ung Jung trong tim mach. DR cao cho phep nhin rd cac cau true cac tang nen no Jtfpc dung trong thani kham bung tong quat. 5. Do ttfting quan (CL - Correlation) Trung hinh hoa theo thdi gian cd the Jtfpc thtfc hien sao che) khi cac thong tin mdi Jirpc ghi vao bd nhd thi mot phan cac thong tin cu van con dtfdc gitf lai. Thong tin da Itfu giti va thong tin mdi nhan diftic ket h cac nha vat K Ja chtfng minh Sieu am Doppler 27 rang hieu ling nay eon xay ra va dung o cac moi trtfOng vat chat dang song khac nhu song radio, song am thanh. Trong llnh vtfc song am. nguyen ly ctia hieu ihig Doppler dupe hieu nhtf sau: khi mot chum sieu am dupe phat di gap mot vat thi se co hien tUpng phan hoi am, tan so cua chum sieu am phan hoi ve se thay doi so vOi tan so cua chum phat di neu khoang cach ttfOng doi gitfa nguon phat va vat thay doi: tan so tang neu khoang cach giam va ngUpc lai. (Hinh 1-18). ~ r r 2.f0.V.cosO Stf thay doi tan so: Af = f - f0 = -------—------ + Af: Thay doi tan so. V / + fo : Tan so phat xa. + f : Tan so phan xa. + V: Toe do vat di chuyen. + 0: Goc giufa chum sieu am va mach mau. * 9 + C: Toe do cua song am trong cP the ( 1.540 m/s). Hinh 1-18. Nguyen ly chung cua hieu ung Doppler. B. Nguyen ly cac kieu sieu am Doppler Co 4 kieu sieu am Doppler: Doppler lien tuc. Doppler xung. Doppler mau va Doppler nang ltfpng. 1. Nguyen lv cua sieu am Doppler lien tuc (continuous wave - C\Y) Day la kieu sieu am Doppler doi hoi cau true may don gian nhat. Dau do cua i ✓ ■> may co chtfa hai tinh the gom ap dien. mot tinh the co chtfc nang phat lien tuc chiim song sieu am va tinh the kia co nhiem vu thu song phan hoi ve. So sanh giufa tan so cua chum sieu am phat va chum sieu am thu \ e la cP so de tinh toe do di chuyen cua vat. Trong cP the thi vat di chuyen de tao nen tin hieu Doppler chinh la cac te bao mau di chuyen trong long mach. trong do chu yeu la cac hong cau. Tin hieu Doppler co the dirpc bieu dien diroi dang 2 8 C h i. Dai cirong ve sieu am chain doan am thanh. (lifting ghi hoac pho. (Hinh 1-19). ■t , Ki6u sieu am Doppler lien tuc co cac ifu diem nhU: cau tao cua may don gian, gia thanh th^p. cho phep ghi dupe cac dong chay co toe do cao. khong co hien tiipng "aliasing” (cat cut dinh). NgUpc lai, kieu Doppler nay co cac nhtftfc di§m nhtf: khong cho phep ghi chon loe 0 mot vung, may ghi lai tat ca cac tin hieu dong chay ma chum sieu am di qua. <•/ W W W W V W W M A M M AIAAAAAAAAAA/ Hinh 1-19. Nguyen ly sieu am Doppler lien tuc. f0: Tan so song phat. f: Tan so song thu. Af: Tan so Doppler = f - f0 2. Nguyen ly sieu am Doppler xung (pulsed wave - PVV) a. Sieu am Doppler xung. dau do chi co mot tinh the gom ap dien. song am difdc phat ra ngat quang dtfdc goi la xung sieu am, xen giufa cac xung sieu am la thoi gian nghi de cac tinh the gom ap dien thu tin hieu cua chum sieu am phan hoi ve. Sieu am Doppler xung da giup giai quvet dupe van de kho khan tham kham mach lien quan den do sau va kich thtfdc mach do sieu am Doppler mau luon gan cung voi sieu am hai hinh dien. (Hinh l -20). Trong kieu sieu am Doppler xung thi chi co tin hieu dong chay of mot vung nhat djnh dtfdc ghi lai Vi tri va the tich viing ghi tin hieu Doppler (con goi la ciifa ghi Doppler) co the tha\ doi dtfpc. Vj tri ctifa ghi Sieu am Doppler 2 9 Doppler dtfdc xac djnh bdi khoang thdi gian tif luc phat don luc thu chum sieu am phan hoi ve. Kich thUdc cua cufa ghi Doppler phu thuoc vao chieu rong cua chum sieu am va khoang thdi gian thu song phan hoi (t). (Hinh 1-21). Hinh 1-20. Hinh so' <3o sieu am Doppler xung. f0: Tan so song phat. f: Tan so song phan hoi. Af: Tan so Doppler = f - f;. P: Do sau cua cija ghi Doppler. L: Kich thudc cua ghi Doppler. T/2 * t T Bau do Cua ghi Doppler Hinh 1-21. So do ghi Doppler. T: Thdi gian tu1 luc phat tdi luc thu song phan hoi. t: Khoang thdi gian thu song phan hoi. 3 0 C h i. Dai cirong ve sieu am chan doan Do van toe cua song am trong cO the kha hang dinh (1.540 cm/s) nen do sau cua vung ghi tin hieu Doppler - d (khoang each tir dau do toi vung ghi tin hieu) dirpc xac dinh theo cong thtfc: T d = — x 1540 (m) 2 + T la thdi gian tir luc phat den luc thu chum sieu am phan hoi. Chi§u dai cua cufa ghi Doppler dupe xac dinh bdi thoi gian thu song phan h6i (t). Chieu rong cua cUa ghi Doppler phu thuoc vao kich thtfdc cua chum sieu am. V / / N ' ' Tan so nhac lai xung (pulse repetition frequency - FRF) la so lan trong mot giay ma chum sieu am di den dich va quay ve. PRF dtfpc tinh bang kHz va thtfPng dupe ghi la K de khong nham voi tan so Doppler (Af cung dirpc tinh bang kHz). C PRF = —2d + d: Chieu sau cua mach mau. / ^ 9 + C: Toe do cua chum sieu am trong cP the (1.540 m/s). •y PRF co y nghia quan trong trong ky thuat ghi pho Doppler vi theo phuong trinh Shannon: 2 Khi Af > PRF/2 thi co hien ttfting “aliasing” , co nghia la dinh pho Doppler bi cat cut va dupe ghi sang phia d6i dien cua dtfpng 0 (dtfPng khong). 9 De tranh hien tupng nay co 4 bien phap: - Chuyen dirong 0 xuong thap, bo cac tan so am de lam tang them cac V ✓ tan so diTPng tren dtfdng 0. - Giam Af bang each giam tan so phat fu (chon dSu do co t£n s6 thikp). hay tang goc 9 de giam CosG tuy nhien goc 9 phai luon < 60° d£ giam sai so. - Giam do sau (d) bang each ep benh nhan de tang PRF. Sir dung may co tan so PRF cao. Voi tien bo cua khoa hoc ky thuat ngiroi ta da che tao dirpc cac may sieu am Doppler co PRF cao bang cach phat di va thu ve nhieu lan tin hieu sieu am trong thoi gian chum song am di toi vat va quay trd lai, nhirng khong phai may sieu am Sieu am Doppler 31 Doppler nao cung co kha nang nay. (Hinh 1-22). Doppler xung 1 xung/giay ‘.2O) Doppler xung 4 xung giay iii TII T 1 PRF cao 0-i cm 2- 4 - 6 - 8-1 c m ------- Bu’dng khong 1 i a b Hinh 1 -22. So do nguyen tic cua PRF cao. a. PRF < 2 Af: Co pho Doppler bi d it cut dinh ngay ca khi da ha dudng 0 xuong thap. b. PRF 4 lan nhanh hdn thi ngay ca khi nang dudng 0 len cao cung khong bi d it cut dinh. Hien nay cac may sieu am xung co ky thuat nhac lai tan so cao (goi la HFRF - high pulse repetition frequency), tuy nhien van co gioi han toi da cua HPRF. do vay sieu am Doppler xung chi cho phep do dirpc toe do cao nhat djnh. 1 - T O So vdi kieu sieu am Doppler lien tuc. kieu Doppler xung co tfu diem nhU: cho phep lira chon chinh xac va thay doi kich thUPc \ ung can ghi tin •7 , hieu Doppler. NgiTpc lai kieu sieu am nay cung co mot so nlurpc diem: - 'V - ' ' . , ^ / \ ■■> han che ve toe do toi da co the do dirpc. han che ve do sau co the tham do cung nhu phu thuoc nhieu vao goc 0. Phan tich tin hieu Doppler xung hay Doppler lien tuc 32 C h i. Dai cifong ve sieu am chan doan Tin hieu Doppler (Doppler lien tuc hay Doppler xung) dtfpc phan tich dtfdi dang am thanh, dtfdng ghi hay dang pho. Do tan so Doppler (Af) nam trong khoang nghe thay cua tai ngtfOi nen v T / chi can dung loa thong thudng co the nghe thay tin hieu Doppler. \ a .7 -> 1 * chan doan cd the dtfa tren sU thay ddi am sac va cudng dd am thanh. Trong kieu the hien tin hieu Doppler bang dtfdng ghi. ngudi ta dung ky thuat dem so lan tin hieu vtfpt tren dudng 0 (zero crossing detector). Tin hieu Doppler dtfpc tinh chung nhtf mot giao ddng. may cho phep tinh dtfdc so lan (tan so) dao dong nay vtfpt qua dtfdng 0. Dtfdng ghi tdc dd khong the hien gia tri Ion nhat. cung khong phai gia tri trung hinh cua ddng chay. no dupe udc tinh - \/Af . Vi vay dudng cong ghi dtfpc khong i i / bieu hien tdc do ttfc thi cua ddng chay ma chi the hien tdc do chung cua cac ddng chay ma chum sieu am gap phai tren dtfdng di. Pho Doppler la ket qua cua stf phan tich tin hieu Doppler (Af) bang phep bien doi nhanh cua Fourier (Fast Fourier Transform - FFT). (Hinh 1- 23, 24. 25). Tin hieu Af iFFT 0 Hinh 1-23. Hop am Sol, Si. Re nghe thay dup'c. phan tich bang FFT thanh ba am cd ban. Tren sieu am thi tin hieu (Af) chu’a nhieu tan so khac nhau. phan tich bang FFT cho phep nhan biet cac tan so khac nhau. Hinh 1-24. Hinh 1-25. Sieu am Doppler 33 Bieu d iin tin hieu pho Doppler tren khong gian ba chieu sau khi da dupe phan tich blng FFT. Hinh pho Doppler cua dong mach canh goc. v ' / \ \ / Tan so Doppler (Af) thu dtfdc la stf ket hop cua nhieu tan so khac nhau (do trong mot ddng chay cd nhieu tdc do khac nhau). Phep hien ddi FFT cho phep phan tich nhanh (trong 5 microsecond) mot tan so Doppler thanh cac tan so thanh phan (hinh tren) va the hien ctfdng dd cua mdi tan so thanh phan nay hang do sang tren difcfng ghi pho Doppler (Doppler spectrum). Nhtf vay pho Doppler dtfdc coi nhtf dtfdng ghi tin hieu theo A • V V N ' khong gian ha chieu: true thoi gian, true tan so (ha\ tdc do) va true thtf ba la true cUdng do (bieu hiC'n bang do sang) cua cac tan so thanh phan. 34 C h i. Dai cuong ve sieu am chan doan 7 *7 Dtfdng cong bieu dien pho Doppler cua dong mach da dtfpc loe bot cac (in hieu tan so thap de loai bo cac cac hieu Ung Doppler cua thanh mach co tan so thap nhtfng cung loai bd bdt cac tan so thap cua ddng cha\ sat thanh mach. Tren ddng mach binh thudng thi cac tan so Doppler cao V S / / ^ -) ^ nhieu hdn cac tan so thap cho nen tao ra cUa so it tin hieu trong thi tarn thu. / * * c. Sieu am Doppler xung ket hefp vdi sieu am cat ldp (he thong Duplex) Tham kham sieu am Doppler de dang nhd gan cung he thong sieu am cat ldp va hien nay tat ca cac may sieu am Doppler xung deu dupe cau tao nhtf vay. Nhd cd he thong sieu am cat ldp ma mach mau dupe de dang nhan thay de dat etfa so ghi Doppler cung nhtf do rong cua no chinh xac phu hop vdi kich thudc cua mach can tham kham. PRF cung cd the dtfpc ttf dong dieu chinh hay dieu chinh tuy theo y muon phu hop vdi tUng mach mau can tham kham cung nhu goc tham kham 0 phu hop. Hinh pho Doppler dupe bieu hien tren man hinh ddng thdi vdi hinh 2D hay rieng biet de de dang phan tich. 3. Nguyen ly sieu am Doppler mau (Color Doppler) (Hinh I -26) Ngtfdi ta ap dung nguyen ly sieu am Doppler xung nhieu ciifa (multigate pulse Doppler) de thu tin hieu Doppler tren mot vung trong mot mat cat. Tin hieu ttf cac ctfa ghi Doppler nay dtfpc ma hoa dtfdi dang mau va the hien V v chong len hinh anh sieu am hai chieu tao thanh hinh Doppler mau con dtfpc goi la ban dd mau cua ddng chay (Color Flow Mapping - CFM). Dudng phat tin hieu Cua ghi Doppler Hinh 1-26. Sd do nguyen ly sieu am Doppler mau. Sieu am Doppler 35 Viec ma hoa tdc do dong chay tren sieu am Doppler mau dtfpc thtfc hien * theo cac nguyen tac: V N 9 V ^ ^ - Cac dong chay ve phia dau do dtfpc the hien bang mau do, ddng chay di xa dau dd dtfpc the hien bang mau xanh. Cd the dao ngtfpc chieu V V -) quy tfdc nay tren may (ddng chay ve dau dd chuyen thanh mau xanh). / 9 V - Ddng chay cd tdc do cang ldn dupe the hien bang mau cang sang: vi du khi tdc do ddng chay cang tang thi mau xanh tham chuyen thanh 9 9 ^ \ \ \ mau xanh ttfOi, mau do chuyen thanh mau xanh la cay va mau vang tham chi thanh mau sang (trang). - Neu tdc do ddng chay ldn se cd hien ttfpng “aliasing” mau: cho tang tdc bien thanh mau ddi lap nhung phai nhat; vi du nhu mau do bien thanh mau xanh nhat. - Neu cd ddng roi (ddng chay Ion xon theo nhieu hudng vdi tdc do khac nhau) thi cd hinh kham mau: cac o do, xanh, vang nam xen lan nhau khong theo trat ttf nao ca. Ma hoa tdc do ddng chay dtfdi dang mau theo nguyen tac tren chinh la ifu 9 diem cua sieu am Doppler mau. Tuy nhien no cd nhtfng nhifdc diem: do cd sd anh/giay thap, do phan giai / / 9 v 9 v x khong gian kem, tdc do the hien tren sieu am Doppler mau khong phai la tdc / 9 \ i) do thtfc, no chi cd tinh chat bieu thj chieu dong chay va the hien mot cach ttfOng ddi tdc do ddng chay. Cho nen sieu am Doppler mau can phai giai quyet mot sd kho khan do la: 7 ' V / V v r V / / \ / 9 - Tin hieu yeu nen can co dau do co tan sd Doppler thap hPn tan sd cua / . / 7 \ sieu am cat ldp va chi mot sd may cd chtfc nang ttf dong thay doi tan so Doppler nay. - Vi chi cd mot dau dd vifa cho cac hinh anh sieu am cat ldp (cd hinh anh rd net nhat khi goc gitfa chum song phat va vat la 9011) va vtfa cho hinh anh Doppler mau (no cd hinh anh rd net nhat khi goc gitfa song am va vat la 0°), muon giai quyet mau thuan nay mot sd may cd dku / / dd det cd mat ngoai vat de tao goc tot cho sieu am Doppler, mot sd 9 9 V may khac cd the thay ddi goc bang phtfPng phap dien ttf. - Phan tich trong thdi gian thtfc rat nhieu cac chi sd, hinh anh sieu am Doppler mau dtfpc tao len do nhieu dtfdng phat tin hieu (L) va tren mdi dtfdng nay lai can co nhieu xung (I) de cd tin hieu tot. de di het chieu dai cua dtfdng phat can cd thdi gian (T) va no ngtfpc lai vdi 3 6 C h i. Dai cuxmg ve sieu am chan doan PRF (PRF cao thi T giam va ngtfpc lai), voi PRF la 5 kH/ thi T khoang 200 microsecond. So ltfpng anh thu dtfpc cho phep phan tich trong thdi gian thtfc va no phu thuoc vao Txl xL. Neu L la 20 dudng va I la 10 xung tren 1 dtfdng va 200 microsecond cho mdi dtfdng phat thi moi hinh anh se mat 40 millisecond va ta cd 25 anh/giay. Ngtfpc lai n6u PRF thap hon, sd xung va sd dtfdng phat nhieu hon thi sd anh se it hon. Chinh vi vay ma tren sieu am mau muon cd nhieu hinh/giay thi cSn phai giam kich thtfdc anh (giam chieu sau de tang PRF. giam chieu rong de giam sd ltfdng dtfdng phat). Do dd de cd the thtfc sir phan tich day du ve hinh thai va tinh chat huyet ddng cua mach mau can phai dua tren sir ket htfp phan tich hinh anh hai chieu, hinh Doppler mau va pho Doppler. May sieu am Doppler mau cd ca 3 kieu / ___ V sieu am nay (he thong Triplex) tao dieu kien thuan lpi cho tham dd mach mau. 4. Sieu am Doppler nang lifting (Power Doppler) hay sieu am angio / / Do tin hieu Doppler thap nen tin hieu Doppler (AO dupe hien ddi ma hoa nang ltfdng. Hinh anh nay dtfpc goi la sieu am nang ltfpng hay sieu am mau ma hoa nang ltfpng. Hinh anh mdi nay khong con la hinh sieu am Doppler mau ntfa va co nhieu 9 diem khac so vdi sieu am Doppler mau: - Khong nhan biet dtfpc chieu cua ddng chay ve phia dau dd hay di xa dau dd. - Toan bo long mach dtfpc lap day cac pixel mau vi Doppler nang ltfpng cd do nhay gap 3 lan Doppler mau va cd hinh anh chup mach tren sieu am Doppler (angio Doppler). Cac mach mau nhd cung dtfpc nhin thay (cac dong mach lien thuy than). - Hinh anh chup nhu mo cd the thay dtfpc. v 9 - Bang sieu am Doppler nang ltfpng cd the phat hien ttfdi mau trong u. cac mach tan tao tang mach trong viem cung cd the dtfpc phat hien. - Khong cd hien ttfpng "aliasing” mau, cung nhtf khong con phai phu thuoc vao goc 9. Sieu am Doppler nang ltfpng dtfpc ufng dung chu yeu trong tham kham cac mach mau nho va nhat la co toe do V 9 / dong chay thap ma sieu am Doppler mau thong thudng khong du dd nhay de phat hien. CHlfONG 2 n h ie u A n h t r £n s i e u A m PGS.TS Pham M in h T h o n g T h s P ham H o n g D u e Co nhieu hinh nhieu hoac hinh gia tren sieu am va tat ca chi dtfdc giai thich hang ban / ^ ^ ,■) / \ ./ 7 ■) chat vat ly. Mot vai hinh nhieu - gia co the co ich va giup ta nhan biet to chufc binh o V ~ „ thudng hay ton thtfdng, nhtfng cd nhieu hinh nhieu - gia khac lam kho tham kham hoac dan den doc sai hinh anh. I. PHAN H 6 l LAP LAI CUA CHUM SONG SIEU AM A. Phan hoi am gitia hai mat phang La ket qua cua mot hay nhieu phan hdi cua song sieu am tren mot mat phan cach ngan cach gitfa hai cau true cd khang trd am khac nhau. Chum song sieu am khong chi tao anh mat phang phan cach that khi no trd ve dau dd de ghi anh ■> v v ma con cd the cd mot ltfdng song am trong chum song am nay khi ve tdi be mat N V , , v v „ dau dd lai doi lai tdi mat phan cach. Phan mem noi suy anh se cong khoang cach di va ve mot hoac nhieu lan nhtf vay cua chum song am. tao ra mot hoac nhi£u mat phang phan cach gia song song vdi nhau. cd khoang cach ttfdng tfng vdi khoang cach cua mat phang phan cach that vdi be mat cua dau dd. va cd dam do ^ V ^ V V V \ am kern rd dan do ltfdng song am phan hdi nhieu lan giam dan (Hinh 2-1). Hinh ** V V ' / 7 nhieu nay lam han che tham kham cac cau true d phia sau. 3 8 Ch2. Nhi£u anh tren sieu am Hinh 2-1. A. Sieu am dau do phang vung thanh bung, co mat phang phan cach la dai can tang am, phia sau co nhung dai tang am gia song song co cung khoang cach vdi mut do tang am kem ro dan. B. Sd do giai thich phan hoi cua chum song am qua lai mot hoac nhieu lan giura mat phSng phan cach va be mat dau dd. V \ \ t V / Hinh do chum song am phan hoi nhieu lan co the gap khi dau do tiep xuc / / , V / -> # khong tot vcfi da, loai bo bang cach cho them dich gel truyen am tot de tranh khi nam xen giufa dau do va mat da (Hinh 2-2A). Hinh nay cung co the gap 0 ldp khi trong ong tieu hoa (Hinh 2-2B). B. Phan hoi am ben trong mot cau true , V , / ' A ~ 0 Do phan hoi cua song sieu am trong mot cau true de phan xa nhtf bot khi / _ i -> , trong ting tieu hoa hoac phoi (Hinh 2-3). va cung co the dtfpc tao thanh tir cau / i ^ true co chat khoang nhtf tinh the cholesterol (Hinh 2-4). Chum song di va ve gitfa be mat trtfdc va sau cua kip khi hay tinh the cholesterol, tao thanh vet sang gom vo so dai trang den xen ke toa ra hinh nan hoa 6 phia sau ldp khi ha> tinh the, tao nen anh nhieu gidng hinh "duoi sao choi”. C. Phan hoi am qua mat phan cach cong Khi chum song am toi mat phan cach cong va phan hoi manh nhu cP hoanh. bang quang..., chung khong trd ve dau dd ma bj lech hudng va tdi mat phang khac. tu mat phang nav chung ddi ngtfpc ve mat phang cong roi mdi trd ve dau do. Phan mem ndi su\ anh dtfdng di lech htfdng nay chi la mot dtfdng Hinh 2-2. Sieu am o bung bang dau dd cong. A. Hinh nhieu phan xa do tiep xuc giife dau dd vdi da khong tot, tao nen nhung vet song song mep ben trai hinh anh (mui ten). B. Hinh nhilu phan xa cua ldp khi trong ong tieu hoa (mui ten sol), tao nen nhung vet sang phia sau (mui ten tir so 2-4). B[ ] A. Sieu am dau dd cong viing day phoi, cd mat phang phan cach la ldp khi tang am, phia sau no cd vo so nhung vet tang am song song. B. Sd do giai thich phan xa cua chum song am di qua lai be mat xa va gan cua ldp khi vdi mot hoac vo so lan roi mdi trd ve dau dd. tao ra nhung vet sang tren hinh sieu am, giong hinh “duoi sao choi”. 4 0 Ch2. Nhieu anh tren sieu am th^ng, gay ra hinh gia cau true doi xiftig vtH cau true that qua mat phan each cong nay, tao nen hinh anh "soi gtfdng” (Hinh 2-5, 6). Hinh 2-4. A. Sieu am tui mat u co' tuyen co nhung hat cholesterol nam trong thanh co hinh "duoi sao choi”. B. Sd do giai thich phan xa cua song am di chuyen theo nhieu hudng trong tinh the cholesterol sau do mdi trd ve dau dd, tao ra nhung vet sang phia sau. Hinh 2-5. A. Sieu am cat doc gan phai. thay cac cau true tren co hoanh "soi gudng' qua co hoanh, thay ro nhat la mat phang khi trong ruot vung duoi gan. B. Sieu am cat doc bang quang tud'ng ttf thay thanh trtfdc bang quang “soi gudng" qua thanh sau. Tang cirong truyen song am 41 B Hinh 2- 6. A. Sieu am gan thay khoi u mau tang am “soi gudng” qua cd hoanh. B. Sd do giai thich hien tudng “soi gudng'’ nay do lech hudng cua chum song phan hoi khi tdi cd hoanh la mat phan cach cong. II. SUY G IA M C H U M S O N G SIEU A m Chum song sieu am khi tdi be mat cau true co khang trd cao (nhu xUdng, voi hoa. 9 ■ ** * ^ v v ^ / / soi, xd hoa. to chufc md...) bj phan hoi manh lam cho be mat cua cau true nay rat tang am; dong thdi vung sau cau true nay khong con hoac con rat it song am truyen qua, hinh nay goi la “bong can lifng” (Hinh 2-7). Bong can co hinh non vdi dau do 9 V ✓ . v V ** re quat, hinh tru vdi dau do phang. ~ 9 ✓ Hinh nhieu nay co ich trong chan doan mot so trUdng hdp benh ly nhu phat hien soi 9 v 9 * 1 cua dudng mat hoac cua he tiet nieu; voi hoa to chufc; xd vufa thanh mach... h i . t A n g c u o n g t r u y £ n s o n g s ie u A m Song sieu am gan nhu khong bi suy giam khi truyen qua dich, nhat la dich thuan nhat. Nen trong mot tang dac (nhu gan. lach, than, tuy...) ma co khoi djch. thi to 9 y ^ V 9 s chuc dac d phia sau nhan dUdc nhieu song am hon so vdi to chufc ke can co cung khoang cach vdi dau do, do vay co hinh anh sang hefn goi la hinh "tang sang phia sau" (Hinh 2-8). Tuong tu hinh bong can. tang sang phia sau co hinh non vdi dSu do re quat. hinh tru vdi dau do phang. Hinh nhieu nay rat co ich trong phat hien nhufng ton thudng cua mot tang dac nhu 9 / V 9 ton thUOng dang nang hoac nhufng khoi viem hoac u chufa nhieu dich hdn to chufc lanh xung quanh. Cac tang rong nhu tui mat. bang quang. da da\... chufa nhiOu djch giiip danh gia tot hdn cau true thanh cua chung. dons thdi co the la cufa so tham 42 Ch2. Nhieu anh tren sieu am kham cac tang d sau nhir hang quang cang giup tham kham tu cung va phan phu tot hon.f B A. Sieu am soi tui mat la hinh dam am co “bong can lung". B. Sd do giai thich hinh “bong can” hinh non phia sau cua dau do hinh de quat. do cau true co khang trd cao can hoan toan song am. r A Hinh 2-8. B A. Sieu am tui mat. nhu mo gan sau tui mat tang sang hdn so vdi nhu mo ke ben co cung do sau. B. Sd do giai th ich hinh "tang sang phia sau" hinh non cua dau do re quat. do chum song am truyen qua cau true dich (L) khong bi suy giam so vdi chum song am qua to chuc ke ben. Phan hoi am cham 4 3 IV. KHUC XA CHUM SONG Sl£u AM Khuc xa chum song sieu am co the xay ra d bd cau true djch hinh tron. Song am truyen lech htfdng lam cho vung dtfdi bd dtfdng cong khong co am, tao nen hinh “hong can bd” (Hinh 2-9). Hien ttfdng gap trong ton thtfdng nang hoac cac tang djch nhu tui mat, bang quang. mach mau ldn... Hinh 2-9. A. Sieu am khoi djch (1) trong nhu mo gan (2), ngoai thay hinh tang sang phia sau con thay hinh “bong can bd” (mui ten). B. Sd do giai thich hien tudng nay do lech hudng cua chum song am di qua hai bd cua cau true nang dich tron (L), tao vung khong co song am di qua (c) gidi han phia ngoai cua vung tang sang phia sau (R). V. CHUM SONG SIEU AM PHU Hinh nhieu nay lien quan den song sieu am khong phai chi la mot chum song am duy nhat d trung tarn, ma co nhieu chum song phu. Hinh anh cd ban dtfdc tao thanh bdi chum song am chinh d trung tarn, nhufng chum song phu thtfdng nhanh chong ■7 . / suy giam. Tuy nhien. trong cau true ma chum song am it bi suy giam nhu djch. anh co the dtfdc tao thanh ttf nhtfng song sieu am cua chum song phu; phan m£m noi suv chi nhan biet mot chum song duy nhat, nen no djch hinh anh trong chum song phu vao trong dtfdng di cua chum song chinh (Hinh 2-10. 11). vi. p h An h 6 i Am cham Chum scSng sieu am phan hdi ve ttf mat mat phan cach co the khong theo dtfdng thang. noi suy anh la mot dtfdng thang co khoang cach xa hdn so vdi khoang cach 4 4 Ch2. Nhiiu anh tren sieu amr Hinh 2-10. A. Sieu am tui mat, trong long vung thap cua tui mat co hinh nhi£u gia bun mat do anh cua khi trong ong tieu hoa ke can (mui ten vang) dutJc dich chuyen va trong long tui mat (mui ten trang). B. Sd do giai thich hien tudng nay: anh tu1 mot vung cau true (r) phan hoi lai ti/ chum song ben, dau do nhan dude am vang nay va ghi nhan chong vao chum song chinh (a), nhu1 vay no tao nen hinh gia nim trong chum song chinh. Hinh 2-11. A. Sieu am buong trung bang dau do qua am dao, hinh nang trung rong am ben trong co vet am vang gia vach (mOi ten). B. Sd do giai thich hien tudng nay la do thanh nang cua chum song am phu khi chong vao chum chinh co khoang cach ngin hdn nen tao hinh gia cua thanh nang n4m trong chum song chinh. Hieu img khoi 4 5 that. Hien ttfdng nay thay ro khi xay ra d thanh cua cac cau true dich (nhu tui mat. hang quang, khoi nang ...), lam nhieu hinh thanh bd cua cac cau true nay (Hinh 2- 12). Dung dau do co tan so cao se tranh duoc hinh nhieu nay. B A. Sieu am bang quang, trong long bang quang d phia sau thanh trudc co nhung diem am vang (mui ten) la hinh nhieu anh do song phan hoi cham gay ra. dong thdi chung la nguyen nhan lam cho thanh trudc cua bang quang kem ro. B. Sd do giai thich hien tudng song phan hoi cham do song phan hoi tren dudng di v§ dau do bi lech hudng vdi vo so nhung khoang cach khac nhau, tao nen vo so diem anh cua mat phlng phan cach nlm xa hdn, va dtfdc thay ro khi phia sau mat phang phan cach nay la cau true dich. V II. T H A Y D O I T O C D O T R U Y E N C U A S O N G SIEU A M V 9 / N Trong cac mo mem co mat do to chuc dich (nhtf gan. lach. than. cd...), toe do truyen / / V 1 , song sieu am ttfdng doi hang dinh la 1.540 m/giay. Nhtfng trong to chufc md toe do dan truyen cua song sieu am giam khoang 1.450 m/giay. Do do, song sieu am di qua to chtfc md se phan hoi am ve dau do cham hdn va do do cac diem anh thu nhan dtfdc d phia sau se xa hefn so v6i nhtfng song am di qua to chtfc md mOm. Hien N ' *> -> 1 / ttfdng nay neu xay ra d gan, co the giup phat hien nhtfng khoi u md lam dui doan cd hoanh (Hinh 2-13), khoi cang ldn hoac nam cang xa cd hoanh thi doan cd hoanh bj dtft doan cang xa hdn so vdi doan binh thtfdng. V III. H IE U U N G K H O I Hinh anh noi suy tren may cua chum song sieu am co do day nhit dinh theo do day ^ V N / / 1 ' ' , cua dau do. do do co the chong cac cau true co mat do am khac nhau. nhat la giufa 46 Ch2. Nhilu anh tr£n si£u am & Hinh 2-13. Sieu am qua vung gan, hinh khoi u m3 tang am, kem bong can am nhe phia sau. Cd hoanh doan tutfng ifng vung bong can nay n§m xa hdn so vdi doan cd hoanh sau nhu mo gan b'inh thuting. tao nen hinh dut doan cd hoanh. Hien tutfng nay dutJc giai thich do toe do truyen song am trong u md cham hdn so vdi nhu mo gan. / / / cau true dich va to chut bao quanh. tao nen anh cua cau true djch nay co cau true am khong that (Hinh 2-14.15). Dieu chinh htfdng cat vao trung tarn vao cau true nay giup loai bo hinh gia nay. IX. HIEU UNG HINH DOI Hieu Ung nay lien quan den hien tudng khuc xa cua chum song am khi di qua mot / 7 cau true co mat cong (nhtf co thang bung, bd dtfdi gan...). noi suy anh se tao nen nhufng hinh gia doi (Hinh 2-16.17). Nhufng hinh gia nay se mat neu thay doi htfdng cat tranh nhufng cau true co mat cong nay. X. TO M LAI Tat ca cac hinh gia hoac hinh nhieu anh tren sieu am deu co the giai thich dupe bang hien tirpng vat ly cua chum song am truyen vao trong moi trtfdng cO th£ co vo so mat phang phan each co khang trd am khac nhau. cung nhtf htfdng truyen va phan v . ■> v V hoi cua chung ve dau do. Cac hinh nhieu hoac hinh gia noi chung khong phai la nhtfng hinh co dinh, nen co the de dang loai bo difdc neu thay doi htfdng cat. vung tham kham tiep can gan nhat vdi dau do. tao cufa so ma chum song am di qua vung tham kham la dong nhat va dieu chinh dung tieu diem va do sans cua ctfa so am. Hieu i/ng khoi 4 7 B Hinh 2-14. A. Sieu am vu, gitia nhu mo tuyen vu tang am co ba khoi nang, khoi ldn nhat la hinh r6ng am djch thuan nhat, hai khoi nho hdn ke ben dang djch giam am; dich chuyen dau do vao chinh giita hai khoi nho nay thi thay la khoi dich rong am. B. Sd do giai thich hien tutfng khoi djch thuan nhat giam am khi ldp cat sieu am lan hai cau true djch va to chut ke can (1), va khoi dich nay se la khoi rong am that sir neu cat vao chinh gitfa dau do (2). Hinh 2-15. A. Sieu am tui mat, trong long tui mat vung thap co am vang giong bun mat. B. So' d6 giai thich hien tutfng nay la do hieu ung khoi ldp cat sieu am qua tui mat lan ca nhu mo gan tao nen hinh gia bun mat. 4 8 Ch2. Nhilu anh tren sieu am Hinh 2-16. A. Sieu am cat ngang vung thudng vj, sau gan trai co hinh gia (Jong mach chu doi. B. Sd do giai thich hien tutfng nay la do chum song am qua mat phang cong cua bd cd th^ng bi khuc xa lech hutfng de tdi cau true roi phan hoi ve dau do, noi suy anh se dich chuyen anh cua cau true la dutfng thang true (dutfng net rdi); cau true ben trai la hinh that. B A. Sieu am cat doc than phai, cut tren than cd hinh anh doi (mui ten), hinh phia tren la hinh gia. B. Sd do giai thich hien tutfng nay la do chum song am bj khuc xa lech hutfng trutfc khi tdi than (mui ten S2). noi suy anh se djch chuyen anh cua cut tren than theo ■> true thang (dutfng net rdi): anh cua cut tren than that su'dutfc tao bdi chum song am khong bi lech hutfng (mui ten S1). C HUONG 3 g iAi p h A u s i e u A m g a n v A d u o n g m a t PG S.TS Pham M inh T hong T h S Pham Ho n g DUc I. GIAI p h Au SIEU Am GAN A. Nhac lai giai phau Gan dirpc tao bdi 8 dcfn vi chufc nang doc lap, moi mot ddn vi co he thong mach mau va dtfdng mat rieng. Cac don vi nay chinh la cac phan thuy dUdc mo ta dau lien bdi nha ngoai khoa va giai phau hoc ngtfdi Phap ten la Claude Couinaud. Nhan biet cac phan thuy nay la rat quan trong giup ngoai khoa xac dinh chinh xac vj tri ton thudng gan. Sieu am cung nhu cac phtfdng phap chan doan hinh anh khac giup nhan dang cac phan thuy gan mot cach ddn gian dtfa vao cac moc giai phau va danh so cac phan thuy nay. Giai phau phan chia gan dtfa tren hinh thai ben ngoai (giai phau hinh thai) va dtfa tren cau true mach mau va dtfdng mat (giai phau chufc nang hoac mach mau). 1. Giai phau hinh thai Giai phau gan theo hinh the ngoai cua no gom co mat tren (mat hoanh) va mat duoi (mat bung). Mat tren co day chang licm phan chia gan thanh thu\ phai ldn va thuy trai nho. Mat difdi co da\ chang tron lien tiep \^ \ doan 50 Ch3. Giai phiu sieu am gan va dirong mat trung tam cua tinh mach ctfa trai (con goi la khe Rex giai phau). Cuong gan gdm tinh mach ctfa, dong mach gan va ong mat di qua, vung gan gan dtfpc goi la “rdn gan” (nga ba tinh mach cufa) va phan chia thanh cuong gan phai ngan va cuong gan trai dai. Cufing gan trai doan g&n n£m ngang va ngan cach thuy vuong P phia trtfdc va thuy duoi 0 phia sau. Doan xa vong len (la doan trung tam di vao trong nhu mo) d6 tiOp noi vdi day chang tron. Mac noi nho noi tir bd trai cua cuong gan, doc theo cudng gan trai, theo day chang tinh mach Arantius tdi tinh mach chu dirdi va co hoanh. No ngan cach thuy trai d phia trudc vdi thuy duoi d phia sau. Cd khoang 107c trudng hpp mot dong mach gan phu (dong mach gan trai) xuat phat tir dong mach vi trai chay trong mac noi nho de tdi cudng gan trai. Day chang tinh mach la di tich cua ong Arantius (con goi la “dng tinh mach”), trong thdi ky bao thai, no noi tuan hoan tir tinh mach ctfa trai vdi tinh mach chu dudi, chay tir goc giufa doan ngang va doan trung tam -> o cua tinh mach cufa trai de dd vao tinh mach gan trai va gitfa. Cuong gan phai cung vdi tui mat tao thanh gidi han bd phai cua thuy vuong. Cudng gan phai dirpc ngan cach vdi tinh mach chu dirdi P phia sau bdi nhu md gan tUOng ufng la phan phai cua thuy dudi. 2. Giai phau chufc nang (mach mau) Nam 1957, nha ngoai khoa va giai phau hoc ngirdi Phap Claude Couinaud da md ta tirong ddi don gian hoa hinh thai cau true mach mau gan va da dupe thira nhan va ap dung pho bien (Hinh 3-1). Nam 1982, Henri Bismuth da 9 ' v v v O v tong ket sir phan chia nay thanh mot so dd don gian, sP dd nay dua vao hai cau true mach: di vao gan la tinh mach cufa (cd dong mach gan va dng mat di cung) va di ra khoi gan la ba tinh mach gan (phai, giufa va trai) dd vao tinh mach chu dudi. Than tinh mach cufa phan chia thanh hai nhanh, phai va trai. di vao gan phai va trai. Ba tinh mach gan phan chia gan thanh 4 phan khu. Tinh mach gan phai ngan each phan khu sau (con goi la phan khu ben phai) vdi phan khu trtfdc (canh gitfa phai). Tinh mach gan gitfa ngan cach gan phai vdi gan trai. nghia la phan khu trtfdc vdi phan khu gitfa (canh gitfa trai). Tinh mach gan trai ngan each phan khu gitfa vdi phan khu ben (ben trai). Hai nhanh ctfa phan chia trong cac phan khu gan thanh nhtfng phan thuy. chung co the dtfpc danh so La-tinh hoac La-ma. Moi phan khu phan chia thanh hai phan thuy. trir phan khu ben trai chi cd mot phan thuy 2. Phan khu canh gitfa trai dtfpc nhanh cufa trai (doan trung tam) phan chia thanh Giai ph iu sieu am gan 51 phan thuy 3 d ben trai va phan thuy 4 (con goi la thuy vuong) d ben phai. Gan phai, hai phan khu trtfdc va sau dtfdc phan chia thanh cac phan thuv theo mat phang nam ngang qua true cua nhanh ctfa phai. Nhu vay, phan khu trtfdc chia thanh phan thuy 8 d phia tren va phan thuy 5 d phia dudi. Phan khu sau thanh phan thuy 7 d phia tren va phan thuy 6 d phia dtfdi. Hinh 3-1. Phan chia thuy gan theo mach mau cua Couinaud. Phan thuy I (con goi la thuy Spiegel, thuy duoi), dtfdc gidi han phia trtfdc la cho phan chia cac nhanh ctfa, phia sau la tinh mach chu dtfdi va ben trai la ranh tinh mach Arantius. Tam phan thuy gan dtfdc danh so theo chieu kim dong ho khi nhin gan ttf V V ^ mat trtfdc, hoac ngtfdc chieu kim dong ho khi nhin ttf phia dtfdi len. Nhin ben ngoai, phan chia gan phai va trai la khong thay dtfdc. Ngtfdc lai. thay dtfdc phan chia thuy gan phai va trai bdi day chang liem. Phan chia gan phai va trai dtfa vao mat phang di qua true cua tinh mach gan gitfa va tinh mach chu dtfdi vdi true cua ho tui mat. Nhtf vay. gan phai gom co phan thuy 5. 6, 7 va 8. Gan trai gom cac phan thuy 2, 3 va 4. Thuy phai gom gan phai va phan thuy 4. Thuy trai la gan trai khong co phan thuy 4. chi co phan thuy 2 va 3. B. Giai phiu sieu am gan binh thtfdng •> ' • v ' -> — Kha nang cho rat nhieu htfdng cat khac nhau cua sieu am giup nhan dang de 52 Ch3. Giai phau sieu am gan va duong mat dang cac moc giai phau va tir do chi ro vung ton thtfdng nam khu tru o phan thuy gan nao Khac vdi hinh cat ngang tren cat ldp vi tinh va cong htfdng ttf. sieu am cho cac ldp cat vdi nhieu htfdng khac nhau nen cd the nhin thav nhieu moc giai phAu tren cung mot ldp. Cac htrfng cat thtfdng dtfpc stf dung la cat quat ngtfpc dtfdi stfdn. cat qua khe lien stfdn. cat dtfng doc va cat ngang. chung giup tham kham nhu md gan va phan chia nhu md gan thanh cac phan thuy theo phan chia cua Couinaud. 1. Hinh thai va cau true cua gan Nhu mo gan cd cau true am ddng deu. cung hoac tang am nhe hdn so vdi vo than (Hinh 3-2). Vo bao gan la dai tang am manh deu. thtfdng khd thay trtf khi dung dau dd nong hoac cd djch trong d bung. Kich thtfdc gan khd danh gia do gan cd hinh dang khac nhau d mdi ngtfdi va htfdng cat de do rat thay ddi. Xen ke nhu md gan cd cau true am deu la nhtfng hinh tang am cua day chang va mach mau. Day chang la cau true hinh dai tang am gdm day chang liC'm va day chang tinh mach. Day chang liem. no bao quanh nhanh ctfa trai xudng mat trtfdc dtfdi gan. la moc phan chia thuy gan phai va trai. Day chang tinh mach ngan cach thuy dudi vdi phan gan con lai (Hinh 3-3). Hinh 3-2. Cat doc thuy gan phai qua than phai. Nhu mo gan tang am nhe so voi vo than. Tinh mach ciifa ttf ron gan phan nhanh vao gan. cd hinh dng rong am. vdi thanh \0 tang am so voi nhu mo gan xung quanh. Di cung cac nhanh ctfa la cac nhanh dong mach gan \a ong mat tang am (Hinh 3-4). Tren sieu am co the thay cac thanh phan ctfa nay 0 gan ron gan. nhtfng d ngoai vi chung rat nho nen khd thay. Cac tinh mach gan trai. gitfa \a phai ve tinh mach chu dtfdi d bd tren sau Giai phcku sieu am gan 5 3 gan (H'inh 3-5). Khac vdi tTnh mach cua. tinh mach gan khong co hao xd va do do thanh it tang am. Co the gap nhtfng bien doi giai phau cua cac tinh mach gan, thong thtfdng nhat la tinh mach gan phai dd trtfc tiep vao tinh mach chu dudi, con tinh mach gan gitfa va trai cd than chung: con lai khoang 5-15% trudng hdp tinh mach gan giura va trai tach rieng re. Hinh 3-3. A. Cat ngang gan trai thay day chang liim (mui ten) la dai tang am noi git/a nhanh cite trai vdi mat trudc cua gan chia gan lam hai thuy trai va phai. B. Cat ngang gan trai thap hdn thay day chlng tinh mach (mui ten dai) gidi han phan thuy I hay thuy cfuoi (mui ten ngan) vdi phan thuy II. Hinh 3-4. A. Bao gan (mui ten) la dai tang am thay tren dau do tan so cao (7.5 MHz). B. Cat ngang khoang cu'a trong gan thay tinh mach cua, di cung la dong mach gan va ong mat (mui ten) deu co thanh xd day tang am 5 4 Ch3. Giai ph^u sieu am gan va dirong mat Hinh 3-5. C lt quat ngutic dutii su’dn qua ba tinh mach gan do vao tinh mach chu dudi. Tinh mach gan gitfa va trai co than chung (A), hoac tach rieng re (B). 2. Phan thuy gan a. Thuy gan trai / i / / Dung cac ldp cat quat ngtfdc dirdi mui tfc. cd the thay cac moc mach mau cua thuy gan trai. Moc dau tien la cac tinh mach gan. tinh mach gan trai ngan cach phan thuy 2 vdi phan thuy 4 va tinh mach gan giufa ngan cach phan thuy 4 vdi phan thuy 8. Cung suf dung ldp cat nay nhtfng d mtfc thap hdn. cd the thay moc thtf hai la nhanh ctfa trai. doan ngang phan nhanh vao phan thuy 2. va doan trung tam cho cac nhanh vao phan thuy 3 va 4, tao nen hinh "chtf H". Cac lop cat ngang dtfOi mui tfc cung co the thay phan thuy 1. Phan thuy 1 dtfdc gidi han phia sau bdi tinh mach chu dtfdi va phia trtfdc bdi doan ngang cua nhanh ctfa trai. Phia ngoai. day chang tinh mach ngan cach phan thuy 1 va 2. Phan thuy 2 va 3 nam ben trai doan trung tam nhanh ctfa trai, day chang tinh mach va day chang liem. Con phan thuy 4 nam ben phai doan trung tam nhanh ctfa trai va day chang liem. Phan thin 4 dtfdc ngan cach vdi phan thu_\ 5 va 8 bdi tinh mach gan gitfa va no dtfdc ngan cach vdi phan thin 1 bdi tinh mach ctfa trai (Hinh 3-6). Sir dung cac ldp dtfng doc ben trai cua day chang tron, thay dtfdc phan thiiv 2 va 3. Chung cd the dtfdc ngan cach bdi dtfdng thang goc qua diem giifa cua bd trtfdc gan trai. Tren cac ldp dtfng doc gitfa day chang tron va tui mat (cat doc qua tinh mach chu dtfdi). thav dtfdc phan thin 4. no ngan cach vdi phan thin 1 bdi da\ chang tinh mach (Hinh 3-7). Hinh 3-6. Hinh sieu am gan trai vdi nhung ldp cat quat ngudc va ngang dudi mui ut. A. Qua tinh mach gan trai va giu’a. ngan cach cac phan thuy dude danh so (2, 4, 8). B. Qua tinh mach cua trai, hinh chu' “H”, phan nhanh vao trong cac phan thuy dude danh so (2, 3, 4), dong thdi thay dude phan thuy 1 gidi han phia trudc la doan ngang tinh mach cu’a trai, phia ben trai vdi phan thuy 2 bdi day chlng tinh mach (mui ten), va phia sau bdi tinh mach chu dudi. Ttrau r Hinh 3-7. Sieu am gan trai cat doc, A. Qua tinh mach chu dudi, phan thuy 1 ngan cach vdi thuy gan trai bdi day chlng tTnh mach. B. Qua ben trai day chSng liem gan, phan thuy 2 va 3 cua thuy trai dup'c phan chia bdi dudng thang goc vdi mat trudc gan, b. Thuy gan phai Tren cac lOfp quat ngtfdc dtfdi stfdn. co the thay hai hoac Jong thoi ca ba tinh mach gan. Tinh mach gan gitfa ngan cach phan thuy S voi phan thuv 5 6 Ch3. Giai phau sieu am gan va dirong mat 4; va tinh mach gan phai ngan cach phan thuy 8 vcli phan thuy 7. Phan thuy 7 nam phia tren ngoai. sat khung stfdn va vom hoanh. Tren cac ldp cat nay qua nga ba cufa. co the thay nhanh cufa phai theo hiring thang. no phan chia nhanh phan khu trtfdc phia nong va phan khu sau phia sau. Cung tren h'lp cat nay chech qua tui mat va cac tinh mach gan. thay phan thuy 4 nam ben trai va phan thuy 5 nam ben phai tui mat: mot dtfdng vach tir tui mat theo true cua tinh mach gan giura la gi&i han phan chia gan phai va trai (Hinh 3-8). Vdi lefp cat ngang dirtli stfdn qua tui mat. co the thay phan thuy 5 va 6. Phan thuy 5 dtfdc gidi han ben trai bdi tinh mach gan gitfa va tui mat. va phan thuy 6 nam ngoai sat khung stfdn. Hai phan thuy nay dtfdc ngan cach vdi nhau bdi mat phang qua tinh mach gan phai (Hinh 3-9). { . . : ' :■ -i f. ■ j Hinh 3-8. Sieu am gan phai, ldp c lt quat nguti'c dudi stfdn. A. Qua cac tinh mach gan phai va giu'a, ngan cach cac phan thuy dtfdc danh so (4. 8, 7). B. Qua tinh mach cua phai va phan chia thanh hai nhanh cho phan khu trtfdc (5 va 8) va sau (6 va 7). Tinh mach ctfa phai va cac nhanh cua no co the thay tren cac ldp lien stfdn dtfng doc hoac cheo qua dtfdng nach gitfa. Tinh mach ctfa phai htfdng chech len tren va trtfdc. Nhanh cho phan thuy 5 va 8 htfdng ra trtfdc tren. ngtfdc lai nhanh cho phan thuv 6 va 7 htfdng ra sau dtfdi. Cac nhanh cua phan thuy 6 va 7 thtfdng co htfdng chech hdn, nen dau do quay nhe len tren doi vdi phan thuy 7 va xudng dtfdi htfcing tdi than phai doi vdi phan thuv 6. C o the thay toan bo cac thuy gan trai va phai itrtf phan thuy 1). tren ldp Giai phau sieu am gan 57 cat quat ngtfdc difdti sifcfn qua ba tinh mach gan. dirpc danh so ngtfpc chieu kim d6ng ho. Cac phan thuy 2. 7.8 nam sau gan tinh mach chu duoi, cac phan thuy 3,5,6 nam vung ngoai vi, rieng phan thuy 4 nam ca sau va nong (Hinh 3-10). •anna 5 6 *•-/ •'j4 • B A. Cat quat ngudc dudi sudn qua tui mat (tm), vdi cac moc tinh mach gan phai (mui ten thing) va tinh mach cua (mui ten cong) giup dinh vi dude cac phan thuy 4, 5, 7, 8. -Dudng ke trang tir tui mat den tinh mach gan giCTa (gan cho do vao) la ranh gidi chia gan phai va trai. B. Cat ngang dudi sudn qua tui mat thay phan thuy 5 canh tui mat va phan thuy 6 canh than phai. Hinh3-10. Sieu am ldp c it quat ngudc dudi sudn qua ba tinh mach gan phai (P). giua (G) va trai (T) dd vao tinh mach chu dudi (TMCD). Dua vao moc mach mau nay. cac phan thuy gan dude danh so theo ngudc chieu kim dong ho (tir 2 den 8). Thay duoc nhanh cua phai (mui ten) n£m trong phan khu trudc (phan thuy 5 va 8). 58 Ch3. Giai phSu si£u Tinh mach cufa co dtfdng kinh thay doi, nhtfng khong qua 16mm va on dinh khi nhin thd. Dtfdng kinh tang sinh ly khi hit sau va sau khi an hoac thay doi ttf thS. Tang dtfdng kinh benh ly gap trong tang ap ltfc tinh mach ctfa do benh gan man tinh. Khong thay tang dtfdng kinh sau khi an cung la dau hieu cua tang ap ltfc tinh mach ctfa. Doppler xung finh mach ctfa binh thtfdng co song mot pha, vdi bien do gdn nhe do nhip thd va nhip tim, bieu hien tinh dan hoi cua gan binh thtfdng. Mat hinh thai song nay co the gap trong xd gan (Hinh 3-11). Hinh 3-11. Doppler ldp cat lien sudn vung cuong gan. A. Doppler mau co dong chay hudng dau do cua than tinh mach cifa (mau do) B. Doppler xung tinh mach ctfa co pho binh thudng, bien do thay doi nhe theo nhip thd. A Toe do dong chay cua tinh mach ctfa la thay doi. trung binh ttf 12-20 cm/giay. Toe do thap thtfdng gap trong tang ap ltfc ctfa. 2. Tinh mach gan Cac tinh mach gan dan ltfu mau ttf gan ve tinh mach chu dtfdi. roi do nga\ vao nhi phai ke can. Dong chay tinh mach gan co pho ba pha do hai dac Giai phiu sieu am gan 5 9 diem: tinh dan hoi cua gan binh thtfdng, giup dong chay ra khoi gan de dang 0 thi nhl tnrdng; va dong nhanh dong chay d thi nhl thu. tao dong chay ngtfdc . o ' 1 vao trong gan (Hinh 3-12). Hinh thai nay cang giam neu do pho tinh mach gan cang xa cho do vao tinh mach chu dirdi. ■ H | B Hinh 3-12. Doppler tinh mach gan. A. Doppler mau thay dong chay cua cac cac tinh mach gan hop ve tinh mach chu dutfi. B. Doppler xung tinh mach gan thay pho binh thudng. Dong chay dao ngudc (mui ten) do nhi thu, cl thdi diem nay (tren hinh Doppler mau phoi hop) dong chay xuat hien mau do. ✓ ✓ ** ' V 0 Cac tinh mach gan co the thay tren Doppler mau vdi dong chay mau xanh ra khoi gan xen lan co dong chay ngtfdc ngan ma do do nhl tong mau. La 0 0 0 hinh thai pho binh thtfdng. Nguyen nhan co the gay ra thay doi song nay: suy o tim. benh gan. va chen ep ngoai gan nhtf co chtfdng. 3. Dong mach gan Dong mach gan xuat phat ttf than tang, gitfdng mach trong gan co stfc can ttfdng doi thap nen co dong chay lien tuc theo nhip tim. Tren ngtfdi binh thtfdng. dong mach gan thtfdng kho thay tren Doppler mau do no qua nho. ngoan ngoeo va cung chieu dong chay tinh mach ctfa nam ngay phia sau. Htfdng cat lien stfdn tao goc nho vdi mach mau. co the thay dong mach gan nam trtfdc mach ctfa va co dong chav toe do cao (bieu hien mau do nhat hdn) (Hinh 3-13). 60 Ch3. Giai phiu sieu am gan va dirong mat Hinh 3-13. Doppler dong mach gan. A. Doppler mau thay phia trudc tinh mach cira mau do la dong mach gan (mui ten) co dong chay cao. B. Doppler xung phoi hop thay pho dong chay dong mach gan binh thudng co dinh tam thu cao (dau mui ten) tiep theo la dinh tam trudng (mui ten) tren dudng 0. D. Bien ddi giai phiu cua gan Bao gom la nhufng hien doi hinh the ngoai va mach mau cua gan. Do la nhufng moc giai phau ma khi chung hi hien doi thi co the lam thay doi gidi han giai phau cua cac phan thuy gan. 1. Bien doi hinh thai ngoai Thuy Spiegel: Thuy Spiegel hay phan thuv 1 la mot thuy hinh tam giac ma dinh d tren, day d dtfdi. Cue dirdi cua thuy Spiegel co hai cu, mot d hen phai V ■> ✓ . V 7 •> 0 goi la cu vuong. mot hen trai la cu nhu. Cu nhu nay co the phi dai va phat trien ve phia thap va sang trai tdi tan tuy. co the nham vdi hach to. Thieu san: Thieu san ham sinh nhu mo gan la hiem gap. Thtfdng gap thu\ trai va phan thuy 4. Trong trtfdng hdp teo phan thuy 4. ngtfdi ta thay tui mat hi ket) len cat) va lan vdi dai trang. Phi dai nhu mo gan: Mot so ngtfdi gay. nhat la d phu nOf, co the gan trai phat trien hdn hao quanh ctfc tren cua kich. Mot so khac. cung thtfdng d phu ntf. cd the co phi dai gan phai hieu hien phan thuy 5 va 6 co the vtfdt dtfdi hd dtfdi than phai va tao nen hien doi hinh thtfdng goi la *'thuv Riedel . thtfdng phdi Imp vdi tlui\ can trai nhd (Hinh V14) 3 2. Bien ddi mach mau Bien doi cac tinh mach gan: Xuat hien them tinh mach gan phai dtfdi. no Giai phau sieu am gan 61 Hinh 3-14. Thuy Riedel. CSt doc thuy phai thay phan thuy 6 loi thap dudi than phai. bo' tu. dan lull cho phan thuy 6, chiem 15-20% 0 ngtfdi hinh thtfdng. Khi tinh mach nay ton tai, tinh mach gan phai thtfdng nho va no khong dan ltfu cho phan thuy 6. Mot so trtfdng hdp, tinh mach gan phai khong co hoac rat nho. thi xuat hien tinh mach gan phai dtfdi gian phoi hdp vdi tinh mach gan phai gitfa ldn (Hinh 3-15). B Hinh 3-15. Sd do bien doi giai phau cac tinh mach gan (A). Sieu am d it doc tinh mach gan gitfa (mui ten) do vao tinh mach chu dudi (B). Bien doi tinh mach ciifa: Chiem 20r/( cac trtfdng hop. Bat thtfdng quan trong va thtfdng thay nhat la tinh mach ctfa chia ha; hoac cac nhanh phan thuy phan chia cho phan thuy 6; hoac tinh mach ctfa trai xuat phat ttf tinh mach ctfa phai hoac ttf nhanh trtfdc cua tinh mach ctfa phai. Ben trai, giai phau it hien doi hdn. hien doi chinh la nhieu nhanh ctfa cho phan thuy 4 hoac cac nhanh phu cho hai phan thuy cua thuy trai. 62 Ch3. Giai phau sieu am gan va duong mat ii. g iAi p h Au sie u Am d u o n g m a t A. Tui mat 1. Nh3c lai giai phiu lien quan vdi phuc mac Mat tren cua than tui mat lien quan chat che vdi ho tui mat cua mat dtfdi *> / gan. Vung nay. tui mat chi dinh vdi gan bdi to chufc xd - te bao va co cac tinh mach cufa phu nho di qua. Phan con lai cua tui mat dtfdc che phu bdi phuc mac lien tuc doc theo bd cua than va cua day tui mat tiep vdi ldp ao phuc mac cua mat dtfdi cua gan. Co tui mat dtfdc bao boc bdi hai la cua mac noi nho va chung lien tiep vdi mat dtfdi cua gan tao thanh mac noi tui mai. 2. Giai phau sieu am Tui mat binh thtfdng thay ro khi tham kham luc doi sau 6 gid. Co the thay ddi ttf the nam nghieng trai. ngoi hoac hit sau de boc lo tui mat dtfdc ro hdn. Tui mat (Hinh 3-16) nam d mat dtfdi gan, canh phai ron gan va cuong gan, V y . V y _ v / / / / hinh tui bau due del vdi dtfdng kinh ldn tren ldp cat doc ttf 8 den 12 cm, dtfdng kinh tren ldp cat ngang trung binh khoang 3,5 cm. Tui mat co thanh ^ v ■> mong deu dtfdi 4 mm. chtfa dich trong, trong trtfdng hdp tf tre tui mat co the co van am ben trong. Hinh 3-16. Binh thudng sieu am tui mat luc doi (A) co djch trong. thanh mong nhu net but chi mong am vang (mui ten); sau an gia day thanh do tui mat co nho (B). 3. Bien doi binh thtfdng ciia tui mat \ i tri: Do mac noi tui mat nam mat dtfdi cua gan co chieu dai thay doi, nen co nhtfng bien doi \ i tri tui mat kem theo. Neu mac treo chi dtfng d co tui mat, thi no rat di dong va sa thap. co the tdi tan ho chau phai. Ngtfdc lai. neu ho tui mat lan sau vao gan thi tui mat dtfdng nhtf nam "trong gan" va dtfdc Giai phiu sieu am dirong mat 6 3 bao bdi nhu nao gan. / / V So lifting: Hiem gap tui mat co vach ngan long hoan toan thanh hai phan. Tui mat doi rat hiem gap va thtfdng nham vdi o djch nam hen canh tui mat tren benh nhan co trieu chufng. Tui mat bat san cung hiem gap (Hinh 3-17). Hinh 3-17. Tui mat doi rat hiem gap va thudng nham vdi o dich nSm ben canh tui mat. Hinh thai: La nhtfng bat thtfdng hay gap hdn ca. Hay gap nhat la tui mat co day bi gap lai giong nhtf hinh mu trum dau. Tui mat co vach ngang d gitfa tao hinh tui mat hai ngan hoac co vach doc (Hinh 3-18). Hiem gap hdn la tui mat that d gitfa hinh tui cat hoac nhieu vach ngan. Nhtfng bat thtfdng ve hinh dang tui mat khong lien quan nhieu den lam sang. B. Dtfdng mat 1. Nhac lai giai phau Dudng mat bao gom dtfdng mat trong gan va dtfdng mat ngoai gan. Dtfcfng mat trong gan xuat phat ttf cac tieu ong trong thuy roi do ra cac ong quanh thuy. Nhtfng ong nay dtfdc noi vdi nhau va hdp lai d khoang ctfa tao thanh nhtfng ong ldn hdn. Dtfdng mat di cung vdi tinh mach ctfa trong gan. nen hdp nhat cua cac ong mat giong stf phan chia cac nhanh ctfa. Moi tinh mach phan thuy co mot hoac hai dng mat di ve ron gan de tao thanh mot ong gan phai va mot dng gan trai. Dtfcfng mat ngoai gan (dtfdng mat chinh) dtfdc hdp bdi dng gan phai va trai thanh dng gan chung. dng gan chung hdp vdi dng tui mat thanh dng mat chu. ' «. > / ' V V 1 / x > dng mat chu hdp vdi dng tuy nam sau dau tuy de thanh dng mat tu\ rdi dd vao doan 2 ta trang d nhu ta ldn. Ve mat giai phau lien quan. no dtfdc chia lam 4 doan: doan rdn gan, doan trong mac noi. doan sau la tu\ \a doan trong 64 Ch3. Giai phau sieu am gan va dirong mat thanh (ta trang). Hai Joan Jau gop phan tao non cuong gan Ji cung la tinh mach cifa va Jong mach gan. Trong Jo. tinh mach cufa nam 0 mat phang ^au cua cuong gan. mat phang trtfrtc gom Jtfdng mat chinh Ji xuong d ben phai va Jong mach gan Ji Icn d ben trai (Hinh 3 -19). A C 0 Hinh 3-18. [\lhimg bien doi cua tui mat. A. B. Tui mat doi. B, C. Tui mat co day gap lai. co the nham vdi tu dich canh tui mat. D, 0, E. Tui mat co vach ngan: ngang. khong hoan toan (D): doc. co the nham voi hinh giun trong tui mat (0): va nhieu vach ngang (E). """