{"id":2623,"date":"2022-09-23T21:25:13","date_gmt":"2022-09-23T14:25:13","guid":{"rendered":"https:\/\/ykhoataynguyen.com\/site\/?p=2623"},"modified":"2024-09-14T18:05:25","modified_gmt":"2024-09-14T11:05:25","slug":"dai-cuong-ve-chan-doan-sieu-am","status":"publish","type":"post","link":"https:\/\/ykhoataynguyen.com\/site\/dai-cuong-ve-chan-doan-sieu-am\/","title":{"rendered":"\u0110\u1ea1i c\u01b0\u01a1ng v\u1ec1 ch\u1ea9n \u0111o\u00e1n si\u00eau \u00e2m"},"content":{"rendered":"<p><b>1. T\u00ednh ch\u1ea5t v\u1eadt l\u00fd c\u1ee7a si\u00eau \u00e2m<\/b><br \/>\n\u00c2m thanh lan truy\u1ec1n trong m\u00f4i tr\u01b0\u1eddng l\u00e0m chuy\u1ec3n \u0111\u1ed9ng c\u00e1c ph\u1ea7n t\u1eed trong<br \/>\nm\u00f4i tr\u01b0\u1eddng, tu\u1ef3 s\u1ed1 l\u1ea7n giao \u0111\u1ed9ng c\u1ee7a c\u00e1c ph\u1ea7n t\u1eed \/ gi\u00e2y c\u00f3:<br \/>\n&#8211; H\u1ea1 \u00e2m: 0-20Hz<br \/>\n&#8211; \u00c2m nghe \u0111\u01b0\u1ee3c: 20HZ &#8211; 20KHZ<br \/>\n&#8211; Si\u00eau \u00e2m: 20KHZ- 1GHZ<br \/>\n&#8211; S\u00f3ng &gt; 1GHZ l\u00e0 b\u1ed9i \u00e2m<br \/>\n&#8211; Trong Y h\u1ecdc d\u00f9ng S\u00c2 t\u1ea7n s\u1ed1 1MHZ- 10MHZ<br \/>\n-Ph\u00e1t x\u1ea1 si\u00eau \u00e2m: t\u1ea5m th\u1ea1ch anh r\u1ea5t m\u1ecfng k\u1eb9p gi\u1eefa hai \u0111i\u1ec7n c\u1ef1c n\u1ed1i v\u1edbi<br \/>\nm\u1ed9t ngu\u1ed3n \u0111i\u1ec7n cao t\u1ea7n xoay chi\u1ec1u. Do hi\u1ec7n t\u01b0\u1ee3ng \u00e1p \u0111i\u1ec7n, nh\u1eefng s\u1ef1 thay \u0111\u1ed5i<br \/>\nc\u1ee7a \u0111i\u1ec7n t\u1eeb tr\u01b0\u1eddng xoay chi\u1ec1u l\u00e0m t\u1ea5m th\u1ea1ch anh co gi\u00e3n v\u00e0 rung: t\u1ea7n s\u1ed1 rung t\u1ef7<br \/>\nl\u1ec7 v\u1edbi t\u1ea7n s\u1ed1 c\u1ee7a d\u00f2ng \u0111i\u1ec7n v\u00e0 ph\u1ee5 thu\u1ed9c c\u1ea3 v\u00e0o chi\u1ec1u d\u00e0y.<br \/>\n-Hi\u1ec7n t\u01b0\u1ee3ng \u00e1p \u0111i\u1ec7n s\u1ea3y ra theo hai chi\u1ec1u, do \u0111\u00f3 ng\u01b0\u1eddi ta c\u00f3 th\u1ec3 d\u00f9ng \u0111\u1ea7u<br \/>\nph\u00e1t si\u00eau \u00e2m l\u00e0m \u0111\u1ea7u thu: s\u00f3ng si\u00eau \u00e2m g\u1eb7p t\u1ea5m th\u1ea1ch anh s\u1ebd l\u00e0m n\u00f3 rung v\u00e0<br \/>\nph\u00e1t ra \u0111i\u1ec7n, t\u00edn hi\u1ec7u \u0111i\u1ec7n thu v\u00e0o hai \u0111i\u1ec7n c\u1ef1c, \u0111\u01b0\u1ee3c khuy\u1ebfch \u0111\u1ea1i v\u00e0 \u0111\u01b0a v\u00e0o<br \/>\nm\u00e0n giao \u0111\u1ed9ng k\u00fd th\u00e0nh nh\u1eefng xung \u0111i\u1ec7n<\/p>\n<p><img decoding=\"async\" class=\"bbCodeImage LbImage\" src=\"http:\/\/langdidong.0fees.us\/wp-content\/uploads\/2015\/11\/CibaCs2-1.png\" alt=\"[\u200bIMG]\" data-url=\"http:\/\/langdidong.0fees.us\/wp-content\/uploads\/2015\/11\/CibaCs2-1.png\" title=\"\"><\/p>\n<p><b>1.1. T\u1ea5n s\u1ed1 ph\u00e1t x\u1ea1 thay \u0111\u1ed5i tu\u1ef3 theo y\u00eau c\u1ea7u<\/b><br \/>\n&#8211; Trong ch\u1ea9n \u0111o\u00e1n ng\u01b0\u1eddi ta th\u01b0\u1eddng d\u00f9ng t\u1ea5n s\u1ed1 si\u00eau \u00e2m t\u1eeb 1MHz \u0111\u1ebfn<br \/>\n10MHz c\u01b0\u1eddng \u0111\u1ed9 5- 10 milliwatt cho m\u1ed7i cm2<br \/>\n&#8211; Trong \u0111i\u1ec1u tr\u1ecb t\u1ea7n s\u1ed1 th\u01b0\u1eddng d\u00f9ng l\u00e0 0,5 \u0111\u1ebfn 1MHz v\u00e0 c\u01b0\u1eddng \u0111\u1ed9 cao h\u01a1n<br \/>\ntrong ch\u00e2n \u0111o\u00e1n nhi\u1ec1u: 0,5-4W cho m\u1ed7i cm2<\/p>\n<p><iframe loading=\"lazy\" src=\"https:\/\/www.youtube.com\/embed\/zpeaJnsCl-E?wmode=opaque\" width=\"100%\" height=\"300\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\" data-mce-fragment=\"1\"><\/iframe><br \/>\n<b>1.2. C\u00e1ch ph\u00e1t x\u1ea1 si\u00eau \u00e2m: C\u00f3 hai c\u00e1ch<\/b><br \/>\n&#8211; Ph\u00e1t x\u1ea1 li\u00ean t\u1ee5c: Th\u01b0\u1eddng d\u00f9ng trong ch\u1ea9n \u0111o\u00e1n v\u00e0 \u0111i\u1ec1u tr\u1ecb ki\u1ec3u Doppler<br \/>\nli\u00ean t\u1ee5c<br \/>\n&#8211; Ph\u00e1t x\u1ea1 gi\u00e1n \u0111o\u1ea1n: Th\u01b0\u1eddng d\u00f9ng trong ki\u1ec3u A,B,TM. th\u1eddi gian m\u1ed7i xung<br \/>\nl\u00e0 2 micro gi\u00e2y v\u00e0 m\u1ed7i gi\u00e2y c\u00f3 500- 1000 xung. Nh\u01b0 v\u1eady th\u1eddi gian ph\u00e1t x\u1ea1 th\u1ee9c<br \/>\ns\u1ef1 kho\u1ea3ng 1-2 milli gi\u00e2y.<br \/>\n<b>1.3 D\u1eabn truy\u1ec1n si\u00eau \u00e2m<\/b><br \/>\nTrong s\u1ef1 d\u1eabn truy\u1ec1n si\u00eau \u00e2m c\u00f3 m\u1ed9t v\u00e0i hi\u1ec7n t\u01b0\u1ee3ng li\u00ean quan \u0111\u1ebfn ch\u1ea9n \u0111o\u00e1n<br \/>\n<b>1.3.1. T\u1ed1c \u0111\u1ed9 truy\u1ec1n si\u00eau \u00e2m:<\/b><br \/>\n&#8211; Trong m\u00f4i tr\u01b0\u1eddng thi\u00ean nhi\u00ean: Trong kh\u00f4ng kh\u00ed t\u1ed1c \u0111\u1ed9 truy\u1ec1n l\u00e0 350m\/s.<br \/>\nSi\u00eau \u00e2m truy\u1ec1n trong kh\u00f4ng kh\u00ed r\u1ea5t k\u00e9m: do \u0111\u00f3 gi\u1eefa ngu\u1ed3n ph\u00e1t si\u00eau \u00e2m v\u00e0 c\u01a1<br \/>\nth\u1ec3 ph\u1ea3i c\u00f3 m\u1ed9t m\u00f4i tr\u01b0\u1eddng d\u1eabn truy\u1ec1n trung gian nh\u01b0 d\u1ea7u n\u01b0\u1edbc<br \/>\nTrong c\u00e1c m\u00f4i tr\u01b0\u1eddng kh\u00e1c si\u00eau \u00e2m truy\u1ec1n t\u1ed1t:<br \/>\n+ Parafin: 1400m\/s<br \/>\n+ N\u01b0\u1edbc: 1500m\/s<br \/>\n+ Th\u00e9p 5000m\/s<br \/>\n&#8211; Trong m\u00f4i tr\u01b0\u1eddng sinh h\u1ecdc:<br \/>\n&#8211; Ph\u1ea7n m\u1ec1m v\u00e0 m\u1ee1 1400m\/s<br \/>\n&#8211; C\u01a1 1600m\/s<br \/>\n&#8211; X\u01b0\u01a1ng 3600- 4000m\/s<br \/>\n&#8211; C\u00e1c b\u1ed9 ph\u1ea7n c\u00f3 nhi\u1ec1u kh\u00ed nh\u01b0 ph\u1ed5i , d\u1ea1 d\u00e0y. ru\u1ed9t si\u00eau \u00e2m r\u1ea5t kh\u00f3 truy\u1ec1n<br \/>\nqua<br \/>\n<b>1.3.2. Ph\u1ea3n x\u1ea1 si\u00eau \u00e2m (h\u00ecnh 2)<\/b><\/p>\n<p>Khi m\u1ed9t ch\u00f9m si\u00eau \u00e2m truy\u1ec1n trong m\u1ed9t m\u00f4i tr\u01b0\u1eddng g\u1eb7p m\u1ed9t m\u00f4i tr\u01b0\u1eddng<br \/>\nth\u1ee9 hai c\u00f3 tr\u1edf kh\u00e1ng \u00e2m thanh kh\u00e1c nhau th\u00ec s\u1ebd s\u1ea3y ra hi\u1ec7n t\u01b0\u1ee3ng ph\u1ea3n x\u1ea1<\/p>\n<p><img decoding=\"async\" class=\"bbCodeImage LbImage\" src=\"http:\/\/langdidong.0fees.us\/wp-content\/uploads\/2015\/11\/7WuVY1h.png\" alt=\"[\u200bIMG]\" data-url=\"http:\/\/langdidong.0fees.us\/wp-content\/uploads\/2015\/11\/7WuVY1h.png\" title=\"\"><\/p>\n<p>&#8211; \u1edf gi\u1edbi h\u1ea1n gi\u1eefa hai m\u00f4i tr\u01b0\u1eddng, m\u1ed9t ph\u1ea7n c\u1ee7a ch\u00f9m si\u00eau \u00e2m s\u1ebd ph\u1ea3n x\u1ea1<br \/>\nl\u1ea1i t\u1ea1o th\u00e0nh nh\u1eefng \u00e2m vang<br \/>\nH\u1ec7 s\u1ed1 ph\u1ea3n x\u1ea1 R c\u00f3 tr\u1ecb s\u1ed1:<\/p>\n<p><img decoding=\"async\" class=\"bbCodeImage LbImage\" src=\"http:\/\/langdidong.0fees.us\/wp-content\/uploads\/2015\/11\/tdAg4Wb.png\" alt=\"[\u200bIMG]\" data-url=\"http:\/\/langdidong.0fees.us\/wp-content\/uploads\/2015\/11\/tdAg4Wb.png\" title=\"\"><\/p>\n<p>Trong \u0111\u00f3<br \/>\nP1 v\u00e0 P2 l\u00e0 t\u1ef7 tr\u1ecdng c\u1ee7a m\u00f4i tr\u01b0\u1eddng th\u1ee9 nh\u1ea5t v\u00e0 th\u1ee9 hai<br \/>\nV1 v\u00e0 V2 l\u00e0 t\u1ed1c \u0111\u1ed9 truy\u1ec1n c\u1ee7a si\u00eau \u00e2m trong m\u00f4i tr\u01b0\u1eddng th\u1ee9 nh\u1ea5t v\u00e0 th\u1ee9 hai.<br \/>\nH\u1ec7 s\u1ed1 ph\u1ea3n x\u1ea1 c\u00e0ng l\u1edbn n\u1ebfu t\u1ed5ng tr\u1edf \u00e2m thanh gi\u1eefa hai m\u00f4i tr\u01b0\u1eddng c\u00e0ng<br \/>\nkh\u00e1c nhau.<br \/>\nV\u00ed d\u1ee5 : Gi\u1eefa m\u00f4 m\u1ee1 v\u00e0 c\u01a1, h\u1ec7 s\u1ed1 R=0,0007 , nh\u01b0ng gi\u1eefa x\u01b0\u01a1ng s\u1ecd v\u00e0 n\u00e3o<br \/>\nh\u1ec7 s\u1ed1 R= 0,36.<br \/>\n&#8211; M\u1ed9t ph\u1ea7n si\u00eau \u00e2m s\u1ebd truy\u1ec1n qua m\u00f4i tr\u01b0\u1eddng th\u1ee9 hai theo h\u01b0\u1edbng c\u1ee7a<br \/>\nch\u00f9m ch\u00ednh. H\u1ec7 s\u1ed1 truy\u1ec1n qua l\u00e0:<br \/>\nT= 1- R<br \/>\nTrong \u0111\u00f3: T l\u00e0 h\u1ec7 s\u1ed1 truy\u1ec1n qua . R l\u00e0 h\u1ec7 s\u1ed1 ph\u1ea3n x\u1ea1<br \/>\n&#8211; C\u00f2n m\u1ed9t ph\u1ea7n si\u00eau \u00e2m n\u1eefa s\u1ebd thay \u0111\u1ed5i h\u01b0\u1edbng, t\u1ea1o th\u00e0nh s\u00f3ng si\u00eau \u00e2m khuy\u1ebfch<br \/>\nt\u00e1n.<br \/>\nTrong ch\u1ea9n \u0111o\u00e1n b\u1eb1ng si\u00eau \u00e2m, ng\u01b0\u1eddi ta thu ch\u00f9m si\u00eau \u00e2m ph\u1ea3n x\u1ea1 (c\u00f2n<br \/>\ng\u1ecdi l\u00e0 \u00e2m vang) bi\u1ebfn th\u00e0nh nh\u1eefng t\u00edn hi\u1ec7u \u0111i\u1ec7n tr\u00ean m\u00e0n hi\u1ec7n s\u00f3ng \u0111\u1ec3 d\u00f9ng v\u00e0o<br \/>\nch\u1ea9n \u0111o\u00e1n. Tr\u00e1i l\u1ea1i trong ch\u1ea9n \u0111o\u00e1n b\u1eb1ng X quang (h\u00ecnh 2A) ng\u01b0\u1eddi ta d\u00f9ng<br \/>\nch\u00f9m tia c\u00f2n l\u1ea1i sau khi \u0111\u00e3 xuy\u00ean qua c\u01a1 th\u1ec3 \u0111\u1ec3 t\u00e1c d\u1ee5ng l\u00ean m\u00e0n chi\u1ebfu hay l\u00ean<br \/>\nphim ch\u1ee5p.<br \/>\n<b>1.3.3. Suy gi\u1ea3m c\u1ee7a si\u00eau \u00e2m:<\/b><br \/>\n&#8211; Nguy\u00ean nh\u00e2n: Sau khi truy\u1ec1n qua m\u1ed9t m\u00f4i tr\u01b0\u1eddng, ch\u00f9m si\u00eau \u00e2m s\u1ebd y\u1ebfu<br \/>\nd\u1ea7n \u0111i. S\u1ef1 suy gi\u1ea3m c\u1ee7a ch\u00f9m si\u00eau \u00e2m c\u00f3 3 nguy\u00ean nh\u00e2n:<br \/>\n&#8211; T\u00e1n s\u1eafc.<br \/>\n&#8211; Nhi\u1ec5u x\u1ea1<br \/>\n&#8211; H\u1ea5p th\u1ee5<br \/>\n\u0110\u00e2y l\u00e0 nguy\u00ean nh\u00e2n ch\u00ednh c\u1ee7a s\u1ef1 suy gi\u1ea3m si\u00eau \u00e2m. Sau khi truy\u1ec1n<br \/>\nqua m\u1ed9t m\u00f4i tr\u01b0\u1eddng, m\u1ed9t ph\u1ea7n n\u0103ng l\u01b0\u1ee3ng \u00e2m s\u1ebd b\u1ecb h\u1ea5p thu v\u00e0 bi\u1ebfn th\u00e0nh<br \/>\nnhi\u1ec7t l\u01b0\u1ee3ng.<br \/>\n&#8211; \u0110o l\u01b0\u1eddng s\u1ef1 suy gi\u1ea3m: Ch\u00fang ta c\u00f3 th\u1ec3 t\u00ednh c\u01b0\u1eddng \u0111\u1ed9 si\u00eau \u00e2m trong s\u00e2u,<br \/>\nsau khi \u0111\u00e3 xuy\u00ean qua l\u1edbp m\u00f4.<br \/>\nIx= Io &#8211; 2FX<br \/>\nTrong \u0111\u00f3:<br \/>\nIo: C\u01b0\u1eddng \u0111\u1ed9 l\u00fac ban \u0111\u1ea7u<br \/>\nIx: C\u01b0\u1eddng \u0111\u1ed9 \u1edf \u0111\u1ed9 s\u00e2u X<br \/>\nF: T\u1ea7n s\u1ed1 c\u1ee7a si\u00eau \u00e2m<br \/>\nX: Chi\u1ec1u d\u00e0y c\u1ee7a m\u00f4 xuy\u00ean qua, t\u00ednh b\u0103ng cm<\/p>\n<p><b>2. M\u00e1y v\u00e0 k\u1ef9 thu\u1eadt si\u00eau \u00e2m<\/b><br \/>\n<b>2.1 Ch\u1ea9n \u0111o\u00e1n si\u00eau \u00e2m ki\u1ec3u A<\/b><br \/>\n<b>2.1.1. Nguy\u00ean l\u00fd:<\/b><br \/>\n\u0110\u1ea7u d\u00f2 ph\u00e1t si\u00eau \u00e2m gi\u00e1n \u0111o\u1ea1n, ch\u00f9m si\u00eau \u00e2m khi xuy\u00ean qua c\u01a1 th\u1ec3 s\u1ebd<br \/>\ng\u1eb7p nh\u1eefng b\u1ed9 ph\u1eadn c\u00f3 tr\u1edf kh\u00e1ng \u00e2m thanh kh\u00e1c nhau, v\u00e0 s\u1ebd cho nh\u1eefng \u00e2m thanh<br \/>\nph\u1ea3n x\u1ea1 tr\u1edf v\u1ec1 t\u00e1c d\u1ee5ng l\u00ean \u0111\u1ea7u d\u00f2 si\u00eau \u00e2m, t\u1ea1o th\u00e0nh nh\u1eefng t\u00edn hi\u1ec7u \u0111i\u1ec7n,<br \/>\nnh\u1eefng t\u00edn hi\u1ec7u n\u00e0y \u0111\u01b0\u1ee3c khuy\u1ebfch \u0111\u1ea1i v\u00e0 \u0111\u01b0\u1ee3c truy\u1ec1n v\u00e0o m\u00e0n hi\u1ec7n s\u00f3ng c\u1ee7a<br \/>\nm\u00e1y giao \u0111\u1ed9ng k\u00fd, bi\u1ec3u hi\u1ec7n th\u00e0nh nh\u1eefng h\u00ecnh xung nh\u1ecdn nh\u00f4 l\u00ean kh\u1ecfi \u0111\u01b0\u1eddng<br \/>\n\u0111\u1eb3ng \u0111i\u1ec7n Ng\u01b0\u1eddi ta g\u1ecdi ki\u1ec3u n\u00e0y l\u00e0 ki\u1ec3u A, do l\u1ea5y ch\u1eef \u0111\u1ea7u c\u1ee7a amplification.<br \/>\nBi\u00ean \u0111\u1ed9 c\u1ee7a c\u00e1c xung t\u1ef7 l\u1ec7 v\u1edbi c\u01b0\u1eddng \u0111\u1ed9 c\u1ee7a c\u00e1c \u00e2m vang. C\u00f2n v\u1ecb tr\u00ed c\u1ee7a<br \/>\nc\u00e1c xung \u0111\u00e1nh d\u1ea5u v\u1ecb tr\u00ed c\u1ee7a c\u00e1c b\u1ed9 ph\u1eadn \u0111\u00e3 ph\u1ea3n x\u1ea1 \u00e2m vang tr\u1edf v\u1ec1. Tr\u00ean m\u00e0n<br \/>\nhi\u1ec7n s\u00f3ng c\u00f3 m\u1ed9t thang \u0111o chia \u0111\u1ed9: m\u1ed7i v\u1ea1ch nh\u1ecf l\u00e0 2mm, v\u00e0 m\u1ed7i v\u1ea1ch to l\u00e0<br \/>\n1cm. Nh\u1edd thang \u0111o \u1ea5y ch\u00fang ta c\u00f3 th\u1ec3 \u0111\u1ecdc ngay kho\u1ea3ng c\u00e1ch gi\u1eefa c\u00e1c x\u1ee5ng v\u1edbi<br \/>\nnhau v\u00e0 v\u1edbi xung \u0111\u00e1nh d\u1ea5u \u0111\u1ea7u si\u00eau \u00e2m.<br \/>\n<b>2.1.2. \u00e1p d\u1ee5ng:<\/b><br \/>\nCh\u1ea9n \u0111o\u00e1n si\u00eau \u00e2m ki\u1ec3u A ng\u00e0y nay \u00edt d\u00f9ng m\u1ed9t m\u00ecnh, m\u00e0 th\u01b0\u1eddng ph\u1ed1i<br \/>\nh\u1ee3p v\u1edbi ki\u1ec3u B. N\u00f3 \u0111\u01b0\u1ee3c \u00e1p d\u1ee5ng trong nhi\u1ec1u chuy\u00ean khoa:<br \/>\n&#8211; Khoa s\u1ea3n: \u0110o \u0111\u01b0\u1eddng k\u00ednh l\u01b0\u1ee1ng \u0111\u1ec9nh c\u1ee7a thai, \u0111o khung ch\u1eadu c\u1ee7a s\u1ea3n ph\u1ee5.<br \/>\n&#8211; Khoa m\u1eaft: \u0110o \u0111\u01b0\u1eddng k\u00ednh nh\u00e3n c\u1ea7u, ph\u00e1t hi\u1ec7n bong v\u00f5ng m\u1ea1c.<br \/>\n&#8211; Khoa th\u1ea7n kinh: Th\u01b0\u1eddng ng\u01b0\u1eddi ta d\u00f9ng ki\u1ec3u A m\u1ed9t m\u00ecnh \u0111\u1ec3 l\u00e0m \u00e2m<br \/>\nvang n\u00e3o \u0111\u1ed3.<\/p>\n<p><img decoding=\"async\" class=\"bbCodeImage LbImage\" src=\"http:\/\/langdidong.0fees.us\/wp-content\/uploads\/2015\/11\/ILphWBf.png\" alt=\"[\u200bIMG]\" data-url=\"http:\/\/langdidong.0fees.us\/wp-content\/uploads\/2015\/11\/ILphWBf.png\" title=\"\"><\/p>\n<p><b>2.2. Ch\u1ea9n \u0111o\u00e1n si\u00eau \u00e2m ki\u1ec3u B<\/b><br \/>\n&#8211; C\u00f2n g\u1ecdi l\u00e0 \u00e2m vang \u0111\u1ed3 c\u1eaft l\u1edbp, \u00e2m vang \u0111\u1ed3 hai chi\u1ec1u. G\u1ecdi l\u00e0 ki\u1ec3u B do<br \/>\nl\u1ea5y ch\u1eef \u0111\u1ea7u c\u1ee7a t\u1eeb Bidimesionnal.<br \/>\n&#8211; Trong ki\u1ec3u n\u00e0y c\u00e1c t\u00edn hi\u1ec7u \u0111\u01b0\u1ee3c chuy\u1ec3n th\u00e0nh \u0111i\u1ec3m s\u00e1ng m\u00e0 \u0111\u1ed9 s\u00e1ng t\u1ef7<br \/>\nl\u1ec7 v\u1edbi c\u01b0\u1eddng \u0111\u1ed9 t\u00edn hi\u1ec7u<\/p>\n<p><img decoding=\"async\" class=\"bbCodeImage LbImage\" src=\"http:\/\/langdidong.0fees.us\/wp-content\/uploads\/2015\/11\/dHSAfWr.png\" alt=\"[\u200bIMG]\" data-url=\"http:\/\/langdidong.0fees.us\/wp-content\/uploads\/2015\/11\/dHSAfWr.png\" title=\"\"><\/p>\n<p>a,b: Ch\u00f9m si\u00eau \u00e2m truy\u1ec1n th\u1eb3ng v\u00e0o c\u01a1 th\u1ec3 v\u00e0 qu\u00e9t ki\u1ec3u ph\u00e2n k\u1ef3 (a) h\u1eb7c<br \/>\nh\u1ed9i t\u1ee5 (b)<\/p>\n<p>c,d: Ch\u00f9m si\u00eau \u00e2m truy\u1ec1n theo h\u01b0\u1edbng ly t\u00e2m r\u1ed3i ph\u1ea3n x\u1ea1 l\u1ea1i v\u00e0 qu\u00e9t ki\u1ec3u<br \/>\nsong song (c). Th\u01b0\u1eddng c\u00f3 hai tinh th\u1ec3 ph\u00e1t si\u00eau \u00e2m g\u1eafn \u0111\u1ed1i di\u1ec7n tr\u00ean m\u1eb7t tr\u1ed1ng<br \/>\nquay v\u00e0 l\u1ea7n l\u01b0\u1ee3t ph\u00e1t x\u1ea1 khi quay v\u1ec1 g\u01b0\u01a1ng l\u00f5m (d).<br \/>\nTrong ki\u1ec3u qu\u00e9t t\u1ef1 \u0111\u1ed9ng b\u1eb1ng m\u00e1y, \u0111\u1ed9 d\u1ed1c qu\u00e9t kh\u00e1 nhanh (16 chu k\u1ef3 1<br \/>\ngi\u00e2y) do \u0111\u00f3 h\u00ecnh \u1ea3nh thu \u0111\u01b0\u1ee3c l\u00e0 m\u1ed9t h\u00ecnh \u1ea3nh \u0111\u1ed9ng v\u00e0 t\u1ee9c th\u1eddi.<br \/>\nH\u00ecnh \u1ea3nh c\u00e1c l\u1edbp c\u1eaft s\u1ebd n\u1ed1i ti\u1ebfp nhau nhanh ch\u00f3ng tr\u00ean m\u00e0n B. Nh\u1edd hi\u1ec7n<br \/>\nt\u01b0\u1ee3ng l\u01b0u \u1ea3nh v\u00f5ng m\u1ea1c n\u00ean ta nh\u00ecn th\u1ea5y h\u00ecnh \u1ea3nh li\u00ean t\u1ee5c, kh\u00f4ng t\u00e1ch r\u1eddi ra<br \/>\nt\u1eebng l\u1edbp: Do \u0111\u00f3 ki\u1ec3u n\u00e0y g\u1ecdi l\u00e0 \u00e2m vang \u0111\u1ed3 \u0111\u1ed9ng th\u1eddi gian th\u1ef1c.<br \/>\nNh\u1edd t\u1ed1c \u0111\u1ed9 qu\u00e9t nhanh, n\u00ean ki\u1ec3u qu\u00e9t t\u1ef1 \u0111\u1ed9ng th\u00edch h\u1ee3p h\u01a1n ki\u1ec3u qu\u00e9t tay<br \/>\nkhi g\u1eb7p nh\u1eefng c\u01a1 quan di \u0111\u1ed9ng nh\u01b0 tim, m\u1ea1ch m\u00e1u.<br \/>\n<b>2.2.1. Qu\u00e9t b\u1eb1ng \u0111i\u1ec7n t\u1eed:<\/b><br \/>\nT\u1eeb n\u0103m 1975 r\u1edf \u0111i xu\u1ea5t hi\u1ec7n m\u1ed9t ph\u01b0\u01a1ng ph\u00e1p m\u1edbi b\u1eb1ng \u0111i\u1ec7n t\u1eed. Ng\u01b0\u1eddi ta d\u00f9ng<br \/>\nnhi\u1ec1u \u0111\u1ea7u qu\u00e9t si\u00eau \u00e2m (kho\u1ea3ng 150) g\u1eafn li\u1ec1n nhau th\u00e0nh m\u1ed9t d\u00e3y: L\u00fac d\u00f9ng<br \/>\nng\u01b0\u1eddi ta \u00e1p c\u1ea3 d\u00e3y \u0111\u1ea7u ph\u00e1t l\u00ean da b\u1ec7nh nh\u00e2n v\u00e0 do \u0111i\u1ec1u khi\u1ec3n b\u1eb1ng m\u1ed9t h\u1ec7<br \/>\nth\u1ed1ng \u0111i\u1ec7n t\u1eed l\u1ea7n l\u01b0\u1ee3t m\u1ed7i \u0111\u1ea7u si\u00eau \u00e2m s\u1ebd ho\u1ea1t \u0111\u1ed9ng t\u1eeb c\u00e1i \u0111\u1ea7u \u0111\u1ebfn c\u00e1i cu\u1ed1i, sau<br \/>\n\u0111\u00f3 l\u1ea1i quay l\u1ea1i c\u00e1i \u0111\u1ea7u: nh\u01b0 v\u1eady c\u0169ng t\u01b0\u01a1ng \u0111\u01b0\u01a1ng nh\u01b0 qu\u00e9t b\u1eb1ng chuy\u1ec3n \u0111\u1ed9ng<br \/>\nc\u01a1 kh\u00ed c\u1ee7a \u0111\u1ea7u ph\u00e1t si\u00eau \u00e2m, nh\u01b0ng t\u1ed1c \u0111\u1ed9 nhanh h\u01a1n nhi\u1ec1u (kho\u1ea3ng 50 l\u1ea7n m\u1ed7i<br \/>\ngi\u00e2y). Tr\u00ean m\u00e0n B, c\u0169ng c\u00f3 m\u1ed9t h\u00ecnh \u1ea3nh \u0111\u1ed9ng t\u1ee9c th\u1eddi.<br \/>\n<b>2.2.2. Ch\u1ecdn t\u1ea7n s\u1ed1 th\u00edch h\u1ee3p<\/b><br \/>\n&#8211; T\u1ea7n s\u1ed1 cao 4-10MHz \u0111\u1ec3 th\u0103m d\u00f2 nh\u1eefng b\u1ed9 ph\u1eadn nh\u1ecf v\u00e0 n\u00f4ng (v\u00fa,<br \/>\nm\u1eaft, tuy\u1ebfn gi\u00e1p) v\u00ec ch\u00f9m si\u00eau \u00e2m \u00edt xuy\u00ean s\u00e2u nh\u01b0ng t\u1eadp trung h\u01a1n.<br \/>\nT\u1ea7n s\u1ed1 th\u1ea5p 1MHz \u0111\u1ec3 th\u0103m d\u00f2 nh\u1eefng ng\u01b0\u1eddi b\u00e9o, nh\u1eefng b\u1ed9 ph\u1eadn d\u1ea7y nhs\u1ecd,<br \/>\nv\u00ec ch\u00f9m si\u00eau \u00e2m xuy\u00ean s\u00e2u nh\u01b0ng ph\u00e2n t\u00e1n.<br \/>\nT\u1ea7n s\u1ed1 trung b\u00ecnh 2-3MHz th\u0103m d\u00f2 v\u00f9ng b\u1ee5ng, tim.<br \/>\n<b>2.2.3. \u0110i\u1ec1u ch\u1ec9nh \u0111\u1ed9 khuy\u1ebfch \u0111\u1ea1i: Mu\u1ed1n c\u00f3 \u0111\u01b0\u1ee3c nh\u1eefng h\u00ecnh \u1ea3nh ki\u1ec3u B<\/b><br \/>\nt\u1ed1t c\u1ea7n bi\u1ebft c\u00e1ch \u0111i\u1ec1u ch\u1ec9nh \u0111\u1ed9 khuy\u1ebfch \u0111\u1ea1i g\u1ed3m c\u00f3: (h\u00ecnh 9)<br \/>\n&#8211; \u0110\u1ed9 xuy\u00ean s\u00e2u c\u1ee7a ch\u00f9m si\u00eau \u00e2m<br \/>\n+ 1MHz \u0111\u01b0\u1eddng k\u00ednh 20cm<br \/>\n+ 2MHz \u0111\u01b0\u1eddng k\u00ednh 20cm<\/p>\n<p>+ 2MHz \u0111\u01b0\u1eddng k\u00ednh 15cm<br \/>\n+ 2MHZ ch\u00f9m h\u1ed9i t\u1ee5.<br \/>\n&#8211; \u0110\u1ed9 khuy\u1ebfch \u0111\u1ea1i to\u00e0n b\u1ed9: L\u00fac \u0111\u1ea7u n\u00ean d\u00f9ng \u0111\u1ed9 khuy\u1ebfch \u0111\u1ea1i y\u1ebfu \u0111\u1ec3 c\u00f3<br \/>\n\u0111\u01b0\u1ee3c b\u1edd c\u1ee7a ph\u1ee7 t\u1ea1ng ho\u1eb7c b\u1edd c\u1ee7a t\u1ed5n th\u01b0\u01a1ng.<br \/>\nSau \u0111\u00f3 d\u00f9ng \u0111\u1ed9 khuy\u1ebfch \u0111\u1ea1i m\u1ea1nh h\u01a1n \u0111\u1ec3 nghi\u00ean c\u1ee9u c\u1ea5u tr\u00fac c\u1ee7a nhu<br \/>\nm\u00f4 ph\u1ee7 t\u1ea1ng.<br \/>\n&#8211; \u0110\u1ed9 khuy\u1ebfch \u0111\u1ea1i kh\u00e1c nhau gi\u1eefa l\u1edbp n\u00f4ng v\u00e0 l\u1edbp s\u00e2u<br \/>\nDo s\u1ef1 h\u1ea5p th\u1ee5 ch\u00f9m si\u00eau \u00e2m c\u00e0ng v\u00e0o s\u00e2u c\u00e0ng y\u1ebfu \u0111i: do \u0111\u00f3 nh\u1eefng \u00e2m<br \/>\nvang \u1edf l\u1edbp n\u00f4ng s\u1ebd m\u1ea1nh h\u01a1n \u1edf l\u1edbp s\u00e2u. V\u00ec v\u1eady khi th\u0103m d\u00f2 nh\u1eefng v\u00f9ng d\u1ea7y c\u1ea7n<br \/>\nph\u1ea3i:<br \/>\n+ Gi\u1ea3m \u0111\u1ed9 khuy\u1ebfch \u0111\u1ea1i \u1edf c\u00e1c l\u1edbp n\u00f4ng<br \/>\n+ T\u0103ng \u0111\u1ed9 khuy\u1ebfch \u0111\u1ea1i \u1edf c\u00e1c l\u1edbp s\u00e2u<br \/>\nN\u1ebfu sau khi \u0111i\u1ec1u ch\u1ec9nh h\u1ebft \u0111\u1ed9 khuy\u1ebfch \u0111\u1ea1i n\u00f4ng, s\u00e2u r\u1ed3i m\u00e0 h\u00ecnh \u1ea3nh v\u1eabn<br \/>\nch\u01b0a t\u1ed1t th\u00ec c\u1ea7n thay \u0111\u1ed5i t\u1ea7n s\u1ed1: d\u00f9ng t\u1ea7n s\u1ed1 th\u1ea5p h\u01a1n \u0111\u1ec3 si\u00eau \u00e2m c\u00f3 kh\u1ea3 n\u0103ng<br \/>\nxuy\u00ean s\u00e2u h\u01a1n.<br \/>\n<b>2.2.4. C\u00e1c b\u1ed9 ph\u1eadn ph\u1ee5: M\u1ed9t s\u1ed1 m\u00e1y c\u00f3 th\u00eam m\u1ed9t s\u1ed1 b\u1ed9 ph\u1eadn:<\/b><br \/>\n&#8211; B\u1ed9 ph\u1eadn l\u1ecdc: B\u1ed9 ph\u1eadn di\u1ec7n t\u1eed n\u00e0y cho ph\u00e9p lo\u1ea1i tr\u1eeb nh\u1eefng \u00e2m vang y\u1ebfu<br \/>\nqu\u00e1 ho\u1eb7c nh\u1eefng \u00e2m vang m\u1ea1nh qu\u00e1, tr\u00ean m\u1ed9t ng\u01b0\u1ee1ng quy \u0111\u1ecbnh, nh\u1edd v\u1eady h\u00ecnh<br \/>\n\u1ea3nh thu \u0111\u01b0\u1ee3c s\u1ebd \u0111\u1ec1u v\u00e0 m\u1ecbn h\u01a1n.<br \/>\n&#8211; \u0110o kho\u1ea3ng c\u00e1ch v\u00e0 chi\u1ec1u s\u00e2u : Khi b\u1ea5m n\u00fat n\u00e0y tr\u00ean m\u00e0n B s\u1ebd hi\u1ec7n m\u1ed9t<br \/>\nthang chia \u0111\u1ed9 cho ph\u00e9p \u0111o k\u00edch th\u01b0\u1edbc v\u00e0 chi\u1ec1u s\u00e2u c\u00e1c t\u1ed5n th\u01b0\u01a1ng, m\u1ed7i v\u1ea1ch<br \/>\nt\u01b0\u01a1ng \u0111\u01b0\u01a1ng v\u1edbi 1cm. C\u00f3 c\u00e1c ch\u01b0\u01a1ng tr\u00ecnh \u0111o kho\u1ea3ng c\u00e1ch, di\u1ec7n t\u00edch , s\u1ea3n, tim<br \/>\nm\u1ea1ch&#8230;<br \/>\n&#8211; Ph\u00f3ng \u0111\u1ea1i \u0111i\u1ec7n t\u1eed: Tr\u00ean h\u00ecnh \u1ea3nh \u1edf k\u00edch th\u01b0\u1edbc b\u00ecnh th\u01b0\u1eddng, ch\u00fang ta<br \/>\nch\u1ecdn v\u00f9ng c\u00e2n ph\u00f3ng \u0111\u1ea1i b\u1eb1ng m\u1ed9t h\u00ecnh \u00f4 vu\u00f4ng tr\u00ean m\u00e0n B. Khi b\u1ea5m n\u00fat<br \/>\nph\u00f3ng \u0111\u1ea1i, v\u00f9ng \u0111\u00f3 s\u1ebd hi\u1ec7n l\u00ean v\u1edbi k\u00edch th\u01b0\u1edbc l\u1edbn h\u01a1n, do \u0111\u00f3 c\u00f3 th\u1ec3 xem r\u00f5 c\u00e1c<br \/>\nchi ti\u1ebft h\u01a1n..<br \/>\n&#8211; M\u00e0n \u1ea3nh c\u00f3 thang \u0111\u1ed9 x\u00e1m: \u0110\u00e2y l\u00e0 m\u1ed9t m\u00e0n g\u1eafn v\u00e0o m\u00e1y, tr\u00ean m\u00e0n n\u00e0y<br \/>\nh\u00ecnh \u1ea3nh khoang ch\u1ec9 c\u00f3 m\u00e0u tr\u1eafng \u0111en m\u00e0 c\u00f2n hi\u1ec7n l\u00ean nh\u1eefng \u0111\u1ed9 x\u00e1m kh\u00e1c<br \/>\nnhau, nh\u01b0 tr\u00ean m\u00e0n \u1ea3nh v\u00f4 tuy\u1ebfn , do \u0111\u00f3 h\u00ecnh \u1ea3nh s\u1ebd r\u00f5, nhi\u1ec1u chi ti\u1ebft h\u01a1n.<\/p>\n<p>Nh\u1eefng m\u00e0n th\u01b0\u1eddng d\u00f9ng c\u00f3 kho\u1ea3ng 8-116 \u0111\u1ed9 x\u00e0m kh\u00e1c nhau tu\u1ef3 t\u1eebng ch\u1ea5t<br \/>\nl\u01b0\u1ee3ng h\u00ecnh \u1ea3nh.<br \/>\n<b>2.2.5. C\u1eaft l\u1edbp:<\/b><br \/>\nL\u1edbp c\u1eaft b\u1eb1ng si\u00eau \u00e2m n\u1eb1m trong m\u1eb7t ph\u1eb3ng c\u1ee7a h\u01b0\u1edbng \u0111i ch\u00f9m si\u00eau \u00e2m.<br \/>\nTr\u00e1i l\u1ea1i, l\u1edbp c\u1eaft b\u1eb1ng X quang th\u1eb3ng g\u00f3c v\u1edbi tr\u1ee5c tia X.<br \/>\nTrong ch\u1ea9n \u0111o\u00e1n b\u1eb1ng si\u00eau \u00e2m ng\u01b0\u1eddi ta th\u01b0\u1eddng c\u1eaft l\u1edbp theo c\u00e1c h\u01b0\u1edbng sau<br \/>\n\u0111\u00e2y:<br \/>\n&#8211; L\u1edbp c\u1eaft ngang: T\u1eeb v\u00f2ng cung \u1edf v\u00f9ng b\u1ee5ng hay v\u00f9ng l\u01b0ng nh\u01b0 gan, th\u1eadn<br \/>\ntu\u1ef5&#8230;<br \/>\n&#8211; L\u1edbp c\u1eaft d\u1ecdc v\u1edbi h\u01b0\u1edbng si\u00eau \u00e2m t\u1eeb tr\u01b0\u1edbc ra sau (nh\u01b0 c\u1eaft l\u1edbp gan, tu\u1ef5) hay<br \/>\nt\u1eeb sau ra tr\u01b0\u1edbc ( th\u1eadn), theo m\u1eb7t ph\u1eb3ng \u0111\u1ee9ng d\u1ecdc.<br \/>\n&#8211; L\u1edbp c\u1eaft ch\u00e9o nh\u01b0: L\u1edbp c\u00e1t ch\u00e9o d\u01b0\u1edbi s\u01b0\u1eddng hai b\u00ean, ch\u00e9o d\u1ecdc c\u00e1c<br \/>\nkhoang gian s\u01b0\u1eddn<br \/>\n&#8211; L\u1edbp c\u1eaft ti\u1ec1n \u0111\u1ea7u theo m\u1eb7t ph\u1eb3ng \u0111\u1ee9ng ngang :d\u00f9ng trong ch\u1ea9n \u0111o\u00e1n si\u00eau<br \/>\n\u00e2m th\u1eadn l\u00e1ch<br \/>\n<b>2.3. H\u1ec7 th\u1ed1ng ho\u00e1 h\u00ecnh c\u1eaft l\u1edbp si\u00eau \u00e2m<\/b><br \/>\nNg\u01b0\u1eddi ta ph\u00e2n lo\u1ea1i hai lo\u1ea1i h\u00ecnh c\u01a1 b\u1ea3n:<br \/>\n<b>2.3.1 H\u00ecnh \u0111\u01b0\u1eddng b\u1edd:<\/b><br \/>\n&#8211; H\u00ecnh li\u00ean b\u1ec1 m\u1eb7t: \u0110\u00f3 l\u00e0 h\u00ecnh gi\u1edbi h\u1ea1n gi\u1eefa hai m\u00f4i tr\u01b0\u1eddng c\u00f3 t\u1ed5ng tr\u1edf<br \/>\nkh\u00e1ng \u00e2m thanh m\u1ea1nh v\u00e0 y\u1ebfu. v\u00ed d\u1ee5 th\u00e0nh m\u1ea1ch m\u00e1u (h\u00ecnh 10a)<br \/>\n&#8211; H\u00ecnh th\u00e0nh: L\u00e0 h\u00ecnh m\u1ed9t v\u1eadt nhi\u1ec1u \u00e2m vang gi\u1eefa hai v\u00f9ng kh\u00f4ng c\u00f3 \u00e2m<br \/>\nvang. v\u00ed d\u1ee5 v\u00e1ch li\u00ean th\u1ea5t, th\u00e0nh c\u1ee7a u nang (h\u00ecnh 10b)<br \/>\n&#8211; H\u00ecnh kho\u1ea3ng tr\u1ed1ng: m\u1ed9t v\u00f9ng tr\u1ed1ng \u00e2m vang c\u1ea3 l\u00fac khuy\u1ebfch \u0111\u1ea1i y\u1ebfu v\u00e0<br \/>\nm\u1ea1nh. \u0110\u00f3 l\u00e0 h\u00ecnh \u0111\u1eb7c tr\u01b0ng c\u1ee7a m\u1ed9t kh\u1ed1i l\u1ecfng hay m\u1ed9t b\u1ecdc n\u01b0\u1edbc (h\u00ecnh 10c)<br \/>\n<b>2.3.2. H\u00ecnh c\u1ea5u tr\u00fac:<\/b><br \/>\n&#8211; C\u1ea5u tr\u00fac \u0111\u1ec1u: Th\u01b0\u1eddng l\u00e0 h\u00ecnh m\u00f4 v\u00e0 nhu m\u00f4 b\u00ecnh th\u01b0\u1eddng. v\u00ed d\u1ee5 c\u01a1, rau<br \/>\nthai, gan&#8230;(h\u00ecnh 10d)<br \/>\n&#8211; C\u1ea5u tr\u00fac kh\u00f4ng \u0111\u1ed3ng \u0111\u1ec1u: Th\u01b0\u1eddng l\u00e0 h\u00ecnh c\u1ee7a nh\u1eefng t\u1ed5n th\u01b0\u01a1ng b\u1ec7nh<br \/>\nl\u00fd. V\u00ed d\u1ee5 : x\u01a1 gan, di c\u0103n&#8230;.(h\u00ecnh 10e).<\/p>\n<p><b>2.4. Ch\u1ea9n \u0111o\u00e1n ph\u00e2n bi\u1ec7t:<\/b><br \/>\n<b>2.4.1. Ch\u1ea9n \u0111o\u00e1n ph\u00e2n bi\u1ec7t gi\u1eefa kh\u1ed1i \u0111\u1eb7c v\u00e0 l\u1ecfng: Ch\u1ea9n \u0111o\u00e1n cho ph\u00e9p<\/b><br \/>\nph\u00e2n bi\u1ec7t t\u00ednh ch\u1ea5t c\u1ee7a u. C\u00e1ch ti\u1ebfn h\u00e0nh nh\u01b0 sau:<br \/>\n&#8211; L\u00fac \u0111\u1ea7u d\u00f9ng \u0111\u1ed9 khu\u1ebfch \u0111\u1ea1i th\u1ea5p (h\u00ecnh a) c\u00f3 h\u00ecnh m\u1ed9t kho\u1ea3ng tr\u1ed1ng<br \/>\nkh\u00f4ng \u00e2m vang.<br \/>\n&#8211; Mu\u1ed1n ph\u00e2n bi\u1ec7t c\u00e0ng t\u0103ng \u0111\u1ed9 khu\u1ebfch \u0111\u1ea1i: N\u1ebfu l\u00e0 m\u1ed9t kh\u00f4\u00ed \u0111\u1eb7c \u1edf trong<br \/>\nkho\u1ea3ng tr\u1ed1ng s\u1ebd xu\u1ea5t hi\u1ec7n nhi\u1ec1u \u00e2m vang (h\u00ecnh b). N\u1ebfu l\u00e0 m\u1ed9t kh\u1ed1i l\u1ecfng m\u1eb7c d\u00f9<br \/>\n\u0111\u1ed9 khu\u1ebfch \u0111\u1ea1i cao v\u1eabn kh\u00f4ng th\u1ea5y \u00e2m vang, h\u00ecnh tr\u1ed1ng \u00e2m v\u1eabn t\u1ed3n t\u1ea1i (h\u00ecnh c),<br \/>\nk\u00e8m t\u0103ng \u00e2m ph\u00eda sau.<br \/>\n&#8211; Ngo\u00e0i ra c\u00f2n c\u00f3 th\u1ec3 th\u1ea5y:<br \/>\n+ H\u00ecnh kh\u1ed1i c\u00f3 c\u1ea5u tr\u00fac n\u1eeda l\u1ecfng n\u1eeda \u0111\u1eb7c: khi t\u0103ng \u0111\u1ed9 khu\u1ebfch \u0111\u1ea1i, trong h\u00ecnh<br \/>\nkhuy\u1ebft s\u1ebd xu\u1ea5t hi\u1ec7n m\u1ed9t v\u00e0i \u00e2m vang nh\u1ecf r\u1ea3i r\u00e1c: h\u00ecnh th\u01b0\u1eddng th\u1ea5y trong tr\u01b0\u1eddng h\u1ee3p<br \/>\nt\u00fai m\u1ee7 hay vi\u00eam t\u1ea5y c\u00f3 ch\u1ee9a m\u1ee7 v\u00e0 ch\u1ea5t l\u1ecfng ho\u1ea1i t\u1eed kh\u00f4ng \u0111\u1ed3ng nh\u1ea5t.<br \/>\n+ H\u00ecnh kh\u1ed1i c\u00f3 c\u1ea5u t\u1ea1o c\u00e1ch ng\u0103n: th\u01b0\u1eddng th\u1ea5y trong u \u0111a nang c\u1ee7a th\u1eadn<br \/>\nv\u00e0 gan&#8230;<br \/>\n<b>2.4.2.Nh\u1eefng nh\u1ea7m l\u1eabn c\u1ea7n tr\u00e1nh:<\/b><br \/>\n&#8211; H\u00ecnh kh\u1ed1i \u0111\u1eb7c gi\u1ea3: Khi d\u00f9ng \u0111\u1ed9 khu\u1ebfch \u0111\u1ea1i l\u1edbn nhi\u1ec1u khi d\u1ecdc theo h\u00ecnh<br \/>\nkhuy\u1ebft c\u00f3 th\u1ec3 th\u1ea5y m\u1ed9t s\u1ed1 \u00e2m vang khu\u1ebfch \u0111a\u1ecb. N\u1ebfu d\u00f9ng t\u1ea7n s\u1ed1 cao h\u01a1n (ch\u00f9m<br \/>\nsi\u00eau \u00e2m t\u1eadp trung h\u01a1n) s\u1ebd th\u1ea5y r\u00f5 l\u00e0 h\u00ecnh m\u1ed9t kh\u1ed1i l\u1ecfng.<br \/>\n&#8211; H\u00ecnh kh\u1ed1i l\u1ecfng gi\u1ea3: Khi d\u00f9ng t\u1ea7n s\u1ed1 cao, khu\u1ebfch \u0111\u1ea1i th\u1ea5p, si\u00eau \u00e2m \u00edt<br \/>\nxuy\u00ean n\u00ean c\u00f3 th\u1ec3 th\u1ea5y m\u1ed9t kho\u1ea3ng tr\u1ed1ng c\u00f3 b\u1edd n\u00f4ng t\u01b0\u01a1ng \u0111\u1ed1i r\u00f5, nh\u01b0ng kh\u00f4ng<br \/>\nth\u1ea5y b\u1edd s\u00e2u. N\u1ebfu d\u00f9ng t\u1ea7n s\u1ed1 th\u1ea5p h\u01a1n \u0111\u1ec3 ki\u1ec3m tra (si\u00eau \u00e2m xuy\u00ean s\u00e2u h\u01a1n, n\u00ean<br \/>\ns\u1ebd th\u1ea5y h\u00ecnh c\u1ea5u tr\u00fac \u0111\u1eb7c ) (h\u00ecnh 11e)<\/p>\n<p><img decoding=\"async\" class=\"bbCodeImage LbImage\" src=\"http:\/\/langdidong.0fees.us\/wp-content\/uploads\/2015\/11\/Ztm1jyg.png\" alt=\"[\u200bIMG]\" data-url=\"http:\/\/langdidong.0fees.us\/wp-content\/uploads\/2015\/11\/Ztm1jyg.png\" title=\"\"><\/p>\n<p><b>H\u00ecnh : Ch\u1ea9n \u0111o\u00e1n ph\u00e2n bi\u1ec7t gi\u1eefa kh\u1ed1i \u0111\u1eb7c v\u00e0 l\u1ecfng<\/b><br \/>\na. Khu\u1ebfch \u0111\u1ea1i th\u1ea5p: c\u00f3 h\u00ecnh khuy\u1ebft<br \/>\nb. T\u0103ng \u0111\u1ed9 khu\u1ebfch \u0111\u1ea1i: h\u00ecnh kh\u1ed1i \u0111\u1eb7c<br \/>\nc. H\u00ecnh kh\u1ed1i l\u1ecfng, kh\u00f4ng \u00e2m vang<br \/>\nd. H\u00ecnh gi\u1ea3 kh\u1ed1i \u0111\u1eb7c<br \/>\ne. H\u00ecnh gi\u1ea3 kh\u1ed1i l\u1ecfng.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>1. T\u00ednh ch\u1ea5t v\u1eadt l\u00fd c\u1ee7a si\u00eau \u00e2m \u00c2m thanh lan truy\u1ec1n trong m\u00f4i tr\u01b0\u1eddng l\u00e0m chuy\u1ec3n \u0111\u1ed9ng c\u00e1c ph\u1ea7n t\u1eed trong m\u00f4i tr\u01b0\u1eddng, tu\u1ef3 s\u1ed1 l\u1ea7n giao \u0111\u1ed9ng c\u1ee7a c\u00e1c ph\u1ea7n t\u1eed \/ gi\u00e2y c\u00f3: &#8211; H\u1ea1 \u00e2m: 0-20Hz &#8211; \u00c2m nghe \u0111\u01b0\u1ee3c: 20HZ &#8211; 20KHZ &#8211; Si\u00eau \u00e2m: 20KHZ- 1GHZ &#8211; S\u00f3ng &gt; &hellip;<\/p>\n","protected":false},"author":11,"featured_media":4495,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[74],"tags":[],"class_list":["post-2623","post","type-post","status-publish","format-standard","has-post-thumbnail","","category-chan-doan-hinh-anh"],"_links":{"self":[{"href":"https:\/\/ykhoataynguyen.com\/site\/wp-json\/wp\/v2\/posts\/2623","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ykhoataynguyen.com\/site\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ykhoataynguyen.com\/site\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ykhoataynguyen.com\/site\/wp-json\/wp\/v2\/users\/11"}],"replies":[{"embeddable":true,"href":"https:\/\/ykhoataynguyen.com\/site\/wp-json\/wp\/v2\/comments?post=2623"}],"version-history":[{"count":1,"href":"https:\/\/ykhoataynguyen.com\/site\/wp-json\/wp\/v2\/posts\/2623\/revisions"}],"predecessor-version":[{"id":2624,"href":"https:\/\/ykhoataynguyen.com\/site\/wp-json\/wp\/v2\/posts\/2623\/revisions\/2624"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/ykhoataynguyen.com\/site\/wp-json\/wp\/v2\/media\/4495"}],"wp:attachment":[{"href":"https:\/\/ykhoataynguyen.com\/site\/wp-json\/wp\/v2\/media?parent=2623"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ykhoataynguyen.com\/site\/wp-json\/wp\/v2\/categories?post=2623"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ykhoataynguyen.com\/site\/wp-json\/wp\/v2\/tags?post=2623"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}