Vật lý lý sinh y học

TRUONG OAI HOC Y HA NOI ■ ■ ■ BO MON Y VAT LY VAT LY LY SINH Y HOC (SACH DUNG CHO SINH VlfiN HE BAC SI DA KHOA) ^ \o U r,; !>■' -\K V IE PKU t h o T H U V i l N s e : fe * r NHA XUAT BAN Y HOC HA NOI - 2006 i& X Dong chu bien: PGS TS Nguyen VSn Thien PGS TSKH Phan Sy An Tham gia bien soan: PGS TSKH Phan Sy An PGS TS Nguyen V9n Thien TS Phan Thi Le Minh ThS Doan Thi Giang Hi/dng CN Nguyen Thanh Thuy ThS Tran Thi Ngoc Hoa ThS Ngo Dung Tuan Thu ky bien soan: ThS Doan Thj Giang Huong LOI NOI DAU Vat ly hoc la mot nganh khoa hoc tU nhien nghien ciiu nhutng dang van dong cd ban nhat cua vat chat roi tim cach ilng dung chung phuc vu ddi song Trong qua trinh phat trien, cac nganh khoa hoc dan xen vao lam sinh cac nganh khoa hoc mcfi, thi du nhU ly sinh, hoa sinh Chiidng trinh Vat ly - Ly sinh difdc day tai trUdng Dai hoc Y Ha Noi tii nam 1956 M uc tieu cua chUdng trinh la giup sinh vien: - Hieu dung cac dinh luat vat ly cd ban co nhieu ling dung sau nghien ciiu y hoc va bao ve sufc khoe cong dong - Phan tich dUdc cac qua trinh, hien tUdng vat ly cd ban xay trdng cd the song - Trinh bay dUdc nguyen ly cua cac ting dung ky thuat vat ly chinh ch&n doan va dieu tri - Phan tich dUdc cac tac dung chinh cua cac yeu to" vat ly len cd the song phuc vu muc dich bao ve moi trUdng va cd the Do do"i tUdng phuc vu chinh la cac sinh vien nam thii nhat trUdng Dai hoc Y nen giao trinh dUdc viet tUdng do"i ddn gian, khong dung nhieu cong cu toan hoc, chi yeu cau ngiidi hoc co kien thilc thong trung hoc ve vat ly va sinh hoc Giao trinh Vat ly - Ly sinh y hoc dUdc viet v6i thdi lildng mon hoc la 75 tiet theo quy dinh khung chUdng trinh cua Bo Y te va Bo Giao due Dad tao 1.1 PhUdng trinh cd ban cua thuyet dong hoc phan tti va cac he qua 55 1.2 Stic cang mat ngoai va hien tUdng mao d&n 57 1.3 Cac hien tUdng van chuyen vat chat cd the 62 1.4 Van chuyen vat chat qua mang te bao 72 Chuyen dong cua chat long va sii van chuyen mau cd the 81 2.1 Cac phan tti va ion cd the 81 2.2 Cac dinh luat ve sU van chuyen cua chat long 82 2.3 Su van chuyen mau 86 Khi va sU van chuyen cd the ngUdi 92 3.1 Hoat dong ho hap 92 3.2 Cac quy luat khuech tan 94 3.3 Su van chuyen cd the 96 3.4 Nhting yeu to' anh hUdng tdi sU trao doi cd the ngUdi 96 Chuyen dong cd hoc tren cd the song 97 4.1 Dai cUdng ve chuyen dong cd hoc 97 4.2 Chuyen dong cd hoc tren cd the song B Dao dong va song Dao dong cd hoc 103 110 110 1.1 Dao dong dieu hoa 111 1.2 Dao dong tat dan 113 1.3 Dao dong cUdng btic va hien tUdng c6ng hUdng 114 1.4 Tong hdp va phan tich dao dong 116 Song cd hoc moi trUdng dan hoi 118 2.1 Moi trUdng dan hoi 118 2.2 Song cd hoc 118 Dao dong va song dien tti 125 3.1 Mach dao dong dien tti Dinh nghia dao dong dien tti 125 3.2 Dao dong dien tti dieu hoa (khong tat) 126 3.3 Su tUdng tU gitia dao dong dien tti khong t i t va dao dong dieu hoa cua lac ddn 128 3.4 Dao dong dien tti tat dan 129 3.5 Cach tao song dien tti 131 Bien doi, khuech dai va ghi giti tin hieu 139 4.1 Bien doi tin hieu khong dien dien 139 4.2 Nguyen ly khuech dai tin hieu dien 141 4.3 Ghi va bao quan tin hieu dien 145 Am va sieu am 148 5.1 Ban chat vat ly cua am va sieu am 148 5.2 Nguon phat am 150 5.3 Cac dac trUng cua cam giac am 152 5.4 So lUdc ve qua trinh nghe 157 5.5 Cd sd vat ly cua phUdng phap am ch&n doan 160 5.6 Sd lUdc ve iing dung sieu am nganh y 162 Song va sU song 167 6.1 Sd lUdc ve tac dong cua song den sU song Tac dong cua song den sU song co loi hay co hai? 167 6.2 Sd lUdc ve nhip sinh hoc 168 Bai D ien va svf song Dien the sinh vat d te bao song 170 171 1.1 Dien the nghi 171 1.2 Dien the hoat dong 175 1.3 SU lan truyen dien the hoat dong 179 Dien the hoat dong cua to chiic song 181 2.1 Dien the hoat dong cua tim 181 2.2 Cac dien the hoat dong khac dUdc dung nhieu chan doan 187 Tac dung cua dong dien len cd the 189 3.1 Phan iing cua cd va than kinh doi vdi klch thich dien 189 3.2 Cac thong so' dien cua cd the 192 3.3 Nguv hiem dien Cac bien phap an toan dien 194 3.4 Tac dung tich cUc cua dong dien len cd the va iing dung y khoa 198 Bai Cac dinh luat quang hinh cd ban - m at Cac dinh luat cd ban cua quang hinh hoc va mot so" dung cu quang hinh 204 204 1.1 Cac dinh luat cd ban cua quang hinh hoc 204 1.2 Mot so dung cu quang hinh 207 Mat va dung cu bo trd 2.1 Quang hinh hoc cua mat 223 223 2.2 Kha nang phan ly cua m&t 226 Cac tat quang hinh cua m&t va dung cu bo trd 229 Bai Ban chat cua anh sang Thuyet song dien tti ve ban chat cua anh sang 235 235 1.1 Thuyet song dien tti ve ban chat cua anh sang 235 1.2 Hien tUOng giao thoa anh sang 238 1.3 Hien tUdng nhieu xa anh sang 244 1.4 Hien tUdng phan cUc anh sang 249 Thuyet lifdng tti ve ban chat cua anh sang 2.1 Hieu ting quang cy.en ngoai 250 250 2.2 Thuyet liidng anh sang cua Einstein va sii giai thich hien tUdng quang dien 252 Cac mtic nang liidng cua tap hdp dien tti 3.1 Mtic nang ltfdng cua tap hdp dien tti 257 3.2 Hap thu anh sang va phat sang 258 Laser 262 4.1 Khai niem ve btic xa cam ting 262 4.2 Laser va may phat tia laser 263 4.3 Sd ltfdc ve ti'nh chat cua chtim tia laser 265 4.4 n g dung cua laser Bai Tac dung cua anh sang len cof the song Dai cUdng ve tac dung cua anh sang len cd the song 265 267 267 1.1 Cac giai doan chinh cua mot qua trinh quang sinh 267 1.2 Phan loai cac qua trinh quang sinh 268 1.3 Mot so" dac diem cua qua trinh quang sinh 268 Mot so qua trinh quang sinh 257 272 2.1 Quang hdp 272 2 Sinh tong hdp sac to" va vitamin 274 2.3 Tac dung quang dong lUc (TDQDL) 275 2.4 Tac dung cua tia tti ngoai len cac he thong song 278 2.5 Thong tin thu cam anh sang 280 Bai Btic xa ion hoa va cd the song Khai niem va nguon goc cua btic xa ion hoa 292 292 1.1 Cau tao hat nhan nguyen tti 292 1.2 Hien tUdng phong xa 293 1.3 Dinh luat phan phong xa 298 TUdng tac cua btic xa ion hoa vdi vat chat 300 2.1 Ttidng tac cua hat vi mo tich dien vdi vat chat 300 2.2 TUdng tac cua photon nang lUdng cao (tia y va tia X) vdi vat chat 303 2.3 Ttidng tac cua neutron vdi vat chat 306 Su hap thu nang lUdng btic xa - Lieu lUdng btic xa 308 3.1 Su hap thu nang lUdng btic xa Su suy giam cUdng btic xa 308 3.2 Lieu ltfdng btic xa 310 3.3 Nguyen ly va cac thiet bi ghi btic xa ion hoa 312 Tac dung cua btic xa ion hoa len vat chat song 317 4.1 Cd che tac dung 317 4.2 Cac ton thUdng d cd the sinh vat dudi tac dung cua btic xa ion hoa 321 4.3 Cac yeu to" anh hUdng den hieu ting sinh hoc cua btic xa ion hoa 327 4.4 Cac nguyen tac ve kiem soat va an toan btic xa 330 Bai 10 M ot so ting dung bien cua V at ly ky thuat nganh Y PhUdng phap hien vi 337 337 1.1 Nguyen ly phong dai anh vat Kinh lup 337 1.2 Kinh hien vi quang hoc trUdng sang (KHVQHTS) 338 1.3 Do phong dai Kha nang phan ly 340 1.4 Cac loai kinh hien vi khac 343 1.5 Cach kich thudc cac vat nho bang kinh hien vi 347 PhUdng phap quang hap thu phan tti 349 2.1 Su hap thu anh sang cua moi trUdng vat chat 349 2 Ung dung cua quang hap thu phan tti 352 PhUdng phap tao anh bang tia X va cong hUdng tti hat nhan 357 3.1 Thiet bi tao tia X 357 3.3 Chup hinh bang cong hUdng tti hat nhan 366 PhUdng phap phong xa 376 4.1 PhUdng phap danh dau phong xa 376 4.2 PhUdng phap dting nguon chieu xa 379 Bai DON Vj DO LltfNG MOT SO QOY LUAT C0 BAN M U C TIEU HOC TAP Trinh bay dUOc vai tro cua vat ly doi vdi cac mon khoa hoc khac, dac biet doi vdi nghien ciiu y hoc va bao ve siic khoe cong dong Van dung dung vdi cac ddn vi lUdng cua nha nude cong tac Neu dUdc nhiing dac diem mang tinh quy luat cua cac hien tUdng ly sinh MO OAU Nhiing phat minh ldn vat ly (cac dinh luat bao toan, tinh chat ltfdng tii ), nhiing thuyet vat ly ve ban chat cua vat chat co dac tinh chung va mot mile khac nhau, co tac dung doi vdi gidi song cung nhu khong song, cho nen co the coi vat ly la cd sd cua moi khoa hoc tu nhien Vat ly va ly sinh (vat ly ve sU song) quan he mat thiet vdi y hoc hien dai la do: - - - Su iing dung cua nhiing quy luat vat ly de nghien ciiu nhiing qua trinh song, de hieu va giai thich nhiing hien tUdng xay tren cd the ngUdi, tren quan the song Su iing dung nhiing phUdng phap vat ly, nhiing may moc trang thiet bi viec chan doan benh, dieu tri benh, bao ve siic khoe cong dong, viec bao ve moi trUdng song Su iing dung nhiing phUOng phap suy nghi dUdc thira nhan vat ly cho viec xay dung the gidi quan khoa hoc cua ngUdi thay thuoc Khi nghien ciiu cac hien tUdng vat ly xay tren vat the song hoac khong song, phUdng phap bien la tao nen mot hoan canh thi nghiem tUdng tii nhu sU kien da xay hoac tao nen mot mo hinh tUdng doi giong nhu hien tUdng dUdc khao sat, tren cd sd d6 ma hoan chinh dan cac dieu kien (thong so) cua hien tUdng Thi du de nghien ciiu ve tim va he tuan hoan, ngUdi ta co the tao nen mot he thong ong dan kin ma ong co tinh dan hoi, mot may bdm vdi cong suat xac dinh hoat dong lien tuc Cho den nay, cac hien tUdng vat ly xay dUdc giai thich bang loai tUdng tac sau: - TUdng tac hap dan: Tiidng tac dUdc dien ta cd ban bang dinh luat hap dan van vat cua Newtdn: hai vat bat ky hut bang mot lUc ti le vdi kho'i lUdng cua chung va ti le nghich vdi binh phUdng khoang cach giiia chung - Tu'dng tac dien tu:: TUdng tac dUdc dien ta cd ban bang dinh luat Coulomb, co dang tUdng tu dinh luat hap dan: hai dien tich hut (hoac day) 11 bang mot luc ti le vdi cac dien tich cua chung va ti le nghich binh phUdng khoang cach gitia chung - TUdng tac hat nhan manh : TUdng tac xay rat dang ke pham vi kich thu6c hat nhan, khoang 10 lD m, no dam bao sU ton tai cua hat nhan nguyen tU - TUdng tac hat nhan yeu : Ttfdng tac dUdc gan lien vdi sU phat xa hat cua hat nhan Cho den nay, tUdng tac dien tii dong vai tro chu yeu vdi hau nhu moi hien tUdng xay d the gi6i song Tuong tac dien tti g^n lien vdi trUdng dien tti Thdi gian gan day, nhieu ngUdi noi den sU ton tai cua trUdng sinh hoc tUdng ting vdi no la sU tUdng tac cua trUdng sinh hdc nhUng ban chat cua trUdng sinh hoc hien v&n chUa dUdc minh chting r5 ret DO Ll/ONG VA DON V| DO 2.1 He lirdng quoc te va he luting hdp phap cua Viet Nam Moi mot thuoc tinh cua mot doi tUdng vat ly dac trUng bang mot hay nhieu dai ltfdng vat ly Mot nhting van de cd ban cua vat ly hoc la van de lUdng cac dai liidng vat ly Do mot dai ltfdng ttic la chon mot dai ltfdng cung loai lam mau (goi la ddn vi) roi so sanh dai liidng phai vdi mau (ddn vi) Tri so^ cua dai lifdng phai bang ty so: dai lUdng phai dai ltfOng ddn vi Muon dinh nghla ddn vi cua mot dai ltfdng, ngUdi ta phai chon trU6c mot so" ddn vi lam mau goi la ddn vi cd ban Cac ddn vi khac dUdc suy tti cac ddn vi cd ban dUdc goi la ddn vi dan xuat Tuy theo cac ddn vi cd ban chon trUdc se suy dUdc nhting ddn vi dan xuat khac Tap hdp cac ddn vi da chon va cac ddn vi dan xuat ttidng ting goi la he ddn vi Cac he ddn vi thUdng dUdc chon cho thoa man mot so yeu cau: cac ddn vi phai tien ldi tinh toan; cac cong thtic vat ly co nhting he so ddn gian va hdp ly; so' lieu khoa hoc dtidc thong nhat gitia cac nude de tien trao doi Trong qua khti, ngUdi ta da dung: - He CGS: ddn vi cd ban la xangtimet (cm), gam (g) va giay (s) - He MKS: ddn vi cd ban la met (m), kilogam (kg) va giay (s) Nam 1960, nhieu nude tren the gidi da hop va chon mot ddn vi thong nhat goi la he SI (Systeme international - he quoc te) Nam 1965, chinh phu Viet Xam da ban hanh “ Bang ddn vi ltidng hdp phap cua nude Viet N a m ” dua tren cd sd he SI Trong he SI ddn vi cd ban la: 12 Ddn vi chieu dai : met (m) Ddn vi khoi l^dng : kilogam (kg) Khi tat sdng radio, tap hdp cac hat nhan dang tti trang thai cong htidng chuyen ve trang thai binh thtidng ban dau Ngtidi ta goi la qua trinh hoi phuc Trong qua trinh nay, vectd tti hoa doc M co ldn tti gia tri khong trd ve gia tri —> ciic dai, vectd tti hoa ngang co ldn tti gia tri ctic dai M L trd ve gia tri khong Tuy nhien thdi gian trd ve, ttic la thdi gian hoi p huc Tj doi vdi vectd tti hoa doc va thdi gian hoi phuc T doi vdi vectd tti hoa ngang khong nhti noi chung T , > T Neu quanh hat nhan co nhieu phan tti nho (nhe), nhti phan tti ntidc H20 , viec hat nhan truyen nang ltidng da hap thu se lau hdn so vdi quanh hat nhan la nhting phan tti ldn, cong kenh, thi du vdi phan tti cua cac chat md, chat beo Vdi cac te bao sinh hoc, ttiy theo chtia l't ntidc nhieu ntidc, l't md hay nhieu md Tj thay doi tti 300 den 2000 miligiay Thdi gian hoi phuc T2 cung se co tri so ldn quanh hat nhan la ntidc va co tri so nho quanh hat nhan la dich chtia cac phan tti ldn hoac nhieu chat md Nhting noi chung, T nho hdn T,, thtidng thay doi tti 30 miligiay den 150 miligiay va so vdi Tj thi nhay cam vdi cau true sinh hoc hdn Neu xet vectd tti hoa tong cong M = M + M L thi cong htidng ( M v = , M ± ctic dai) dau —> mut cua M vach nen vong tron —> mat phang vuong goc B Khi tat song radio, M ± vtia quay tron, vtia co nho lai luc -> _ ^ M tti gia tri bang khong, ldn Hinh 10.33 Khi tat song radio, dau mut cua vectd tu1hoa M vach nen dudng xoan oc nho dan dtin len Do dd dau mut cua M vach nen mot dudng xoan oc nhd dan (Hinh 10.33) Ve nguyen tac, neu de mot cuon day dien gan day thi bien thien tti trtidng —► M gay se lam thay doi tti thong qua cuon day va sinh ddng dien cam ting cuon day Trong ki thuat cong htidng tti ngtidi ta bo tri angten de phat sdng radio theo tting xung, xung tat, qua trinh hoi phuc nhti da mo ta d tren xay —> va angten cung thu ddng dien cam ting sinh vectd tti hoa A ! bien thien theo dtidng xoay tron oic Tin hieu angten thu dtidc cd ten la tin hieu cam ting suy giam tti FID (tree induction decay) Ban than tin hieu FID nav manh hav veu la vectd tti 371 —> —> hoa M ldn hay nho, ma ldn cua M lai phu thuoc vao so hat nhan phan tii the tich, cu the d day la so proton Vi vay tin hieu FID cho biet mdt proton Phan tich ki dang cua tin hieu FID co the tim dtidc thdi gian hoi phuc tu hoa ngang T2 v.v Nhti vay neu chia cat cd the ngtidi tting the tich nho co toa x y, z ttidng ting, lam cho cac hat nhan the tfch dao dong cong htidng va thu tin hieu cong htidng tti the tich dd gtii di, thi du tin hieu FID thdi gian hdi phuc T,, thdi gian hoi phuc T, v.v va quy dinh dam, nhat trang den hoac mau sac xanh tim vang ting vdi tin hieu manh yeu, dai, ngan thu dtidc tren cd sd so lieu cac toa x, y, z cua phan tti the tfch va tin hieu cong htidng thu dtidc tti phan tti dd, thi may tfnh co the ve tren man hinh anh cat ldp hai chieu hoac anh ba chieu cua cd the Tuy theo tin hieu thu de tao anh manh hay veu anh cd the cho biet dau la ntidc, dau la chat md, mau, xtidng v.v 3.3.2 Chup anh cat lop cong hu’dng turhat nhan Trtidc het ta xet cach thiic hien cong htidng tti hat nhan d phong thf nghiem nghien ctiu tfnh chat vat lieu Thiet bi gom mot nam cham vinh ctiu May phat RF va may —y de tao tti trtidng deu B0 gitia hai ctic (hinh 10.34) Gia sti mau nghien ctiu dat mot o'ng hinh tru chung quanh co cuon day dien, tti trtidng B { tao bdi cuon day vuong goc vdi B{] —y Ngtidi ta dieu khien tan so' cua B, cho xay phat vo vao tan Hinh 10.34 So may cong hu’dng tii hat nhan d phdng thi nghiem co hien ttiOng cong htidng tti Luc cong sua't cua may tuyen tang vot han Nhti vay, theo ddi cong sua't d may phat phu thuoc so, ta xac dinh dtidc nhting tan so' ting vdi co cong htidng tti xay —^ mau Moi bien thien cua momen tti tong cong M ^ cua m l u deu co the gay nen —t dong cam ting cuon day dat chung quanh mau theo nguyen t ic : M bien thien lam bien thien tti thong di qua cuon day, bien thien tti thong sinh dong —> dien cam ting Neu bo tri cuon day vuong goc vdi B ta dtidc bien thien cua phan M song song vdi B ttic la \1 Tti ta dtidc thdi gian hoi phuc doc Neu bo tri cuon day song song vdi BC) ta dtidc bien thien cua t nh phan vuong goc M j_ , tti dd xac djnh dtidc thdi gian hoi phuc ngang Cac tin h:eu rr.a cac 372 cuon day thu dtiOc rat nho, r&'t n g i n nhitng ki t h u a t xti If tin hieu cho phep kha chi'nh xac Giai phap kT thuat quan nhat de co dtiOc anh cat 16p cong htidng tit hat —» nhan la Lauterbur dtia nam 1973 Do la them vao tti trtidng manh B [} cac tti trtidng yeu nhting bien thien deu theo khoang cach, noi cach khac la tao cac gradien tti trtidng Trtidc het ta xet cach tao tti trtidng co gradien theo z va tac dung cua tti trtidng —> Cuon day sieu dan tao mot tti trtidng B rat manh va rat deu Ngtidi ta —> bo tri them mot cuon day tao mot tti trtidng yeu song song vdi B0 nhting bien thien deu theo z, ttic la co dang B, = ( a + (3z ) B Vay tti trtidng tong cong ben cuon day sieu dan la: B0+ B, = (l + a + (3z).50 Tti trtidng rat manh, bien thien deu theo z: tti trtidng ben hinh tru bi chia tting ldp mong, vuong goc vdi true z Trong pham vi mot ldp, tti trtidng co the xem la khong thay doi Khi di tti ldp den ldp tti trtidng tang dan, thi du nhti d hinh ve 10.35 la 0,97T, 0,98T, 0,99T, IT, 1,01T, 1,02T, 1.03T, Co the ngtidi dtiOc dat hinh tru rong, xet ve mat tti co the chia lam nhieu ldp : ldp nam tti trtidng 0,97T, ldp n&m tti trtidng 0,98T v.v Tan sd cua chuyen dong dao cua momen tti hat nhan phu thuoc vao tti trtidng ngoai, thi du do'i vdi hat nhan nguyen tti hidro, tti trtidng ngoai la IT, tan so" chuyen dong dao la 42,58 MHz Hinh 10.35 Do Bz co gradien theo z khong gian hinh tru dirge chia nhting ldp cat mong vuong goc vdi z, tti tri/dng B0 +BZ moi ldp co the xem la khong doi Khi cO the nam tti trtidng ngoai co gradien theo z, neu chieu song radio co tan so 42,58 MHz vao ca co the thi chi co cac hat nhan nguyen tti hidro nam tti trtidng IT mdi bi cong htidng Nhti vay nhd cuon day tao gradien tti trtidng theo true z ta co the tao cong htidng tti hat nhan chi mot ldp vuong goc vdi z Ldp day hay mong la thuoc vao tti trtidng bien thien nhanh hay cham, ttic la phu thuoc ldn dH/dz cua tti trtidng Co the dich chuyen vi tri cong htidng bang hai cach : Cach : giti nguyen tan so cua song radio, dich chuyen gradien tti trtidng Cach : giti nguyen gradien tti trtidng thay do’i tan sd cua song radio 373 CJ may tao anh c i t ldp cong hudng tii c6 t&'t ca ba cuon tao gradien tii triidng theo phiidng x, phiidng y va phudng z Phoi hdp sti dung ca ba cuon ve nguyen tfic co the tao diidc cong hiidng tii mot phlin tu the tich c6 toa x, y, z cua cd the va thu lay tin hieu cong hiidng tii tti the tich phat C6 the dieu khien de chon mot ldp c i t va lan ltidt quet p h in tu the tich cong hudng theo toan bo dien tich cua ldp c it TU tap hdp cac so" lieu ve tin hieu cong htidng va %1 tri tUdng Ung may tinh co the tao anh cong hudng tti cua ldp c it Thu thap so lieu tti cac ldp c i t lien tiep nhau, may tinh co the diing lai anh ba chieu khong gian cua doi tudng Tuy thuoc vao viec lay tin hieu cong hudng nao de tao anh va cong hudng xay doi vdi hat nhan nao, anh c i t ldp cong hudng tti se cho ta cac thong tin tUdng ting Thi du, tin hieu cam ting tti suy giam FID phu thuoc v&o ldn cua vecto tti hoa M cua phan tti the tich ma M lai phu thuoc vao so m om en tti cua proton, do tin hieu manh hay yeu phu thuoc vao mat proton ldn hay nho, tti ta co the ly giai nhting cho dam nhat tren anh co the tUdng ting vdi nhting chat nao (hinh 10.36) Thong thudng ngudi ta hay sti dung tin hieu lien quan den thdi gian hoi phuc Mat dd proton doc va ngang Nhu da neu tren, cac thdi E gian hoi phuc T, va T rat phu thuoc «C W X C phan tti the tich chtia chat gi : chat nUdc, '> C •O -a ■3 manh B0 , gradien tti trtidng va sdng radio 374 Hinh 10.37 May chup hinh bang cong hu'dng ti/ hat nhan (hinh tren) Hinh anh mat cat doc cua v u n g dot song co (hinh di/di, ben trai) va hinh anh mat cat ngang cua song (hinh di/di, ben phai) 375 Tti triidng tinh B0 dtidc sii dung thiidng vao cd Tesla trd len manh gap 20.000 l i n tif trifdng Trai Dat Theo nhieu ket qua nghien ciiu tif triidng manh vao cd tham chi den 2,5 Tesla van chiia co tac hai gi den co the Con gradien tii triidng bien thien manh cung chi gay cd the dong dien cam iing vdi mat dong vao cd lp A /cm Gia tri cung qua nho khong gay hai gi Diidi tac dung cua song radio chieu vao, cd the chi hap thu het 0,7 W, tuong iing chi co the lam nhiet co the tang cd 0,1-0,2°C Dieu han che cua phuong phap cong htidng tif hat nhan la cd the khong dtidc co manh kim loai, vat lieu tif, thi du manh bom, vien dan sot lai neu co diidi tac dung cua tif triidng cac loai vat lieu tif se bi hut manh va nong len Dac biet la nhiing ngtidi dung may trd tim, neu dua vao tif trtidng manh, may bi hdng va ngtidi mang may kho tranh khoi tti vong PhtiOng phap chup anh cat ldp cong htidng tti hat nhan cd nhieu tiu diem so vdi cac phtidng phap chup anh cat ldp khac y hoc Tin hieu cong htidng de tao dam, nhat, den, trang hay mau sac tren anh rat nhay cam vdi cau tao, td chtic sinh hoc cua CO the Tren anh cac to chtic, cac chd bat thtidng nhti mach mau bi ran ntit, mau ri ngoai, kho'i u nhd chen day t h in kinh rat de phan biet va phat hien PHUONG PHAP PHONG XA Ngay tren the gidi phtiOng phap phdng xa dang dtidc sti dung nhieu nganh khoa hoc ky thuat va km h te No dtidc sti dung rat rong rai y sinh hoc Trong y hoc ngoai viec dting btic xa de tieu diet cac yeu td gav benh va te bao benh, ting dung ky thuat danh dau bang ddng vi phdng xa (dvpx) vao cac chuyen khoa khac nhau, ban than no tao mot chuyen khoa mdi la y hoc hat nhan (yhhn) B in g cac phtiOng tien khac nhau, cac ket qua ghi hoat phdng xa dtiOc the hien bang nhieu hinh thtic: so" xung, thi, hinh anh Tti dd cac thay thuoc cd the danh gia cau true chtic nang va c h i n doan benh Dtidi day gidi thieu nhting ky thuat va noi dung chinh cua phtiOng phap sti dung cac dvpx vao y sinh hoc 4.1 Phirong phap danh dau phong xa 4.1.1 C a s a cua phuong phap danh dau phdng xa Cho den viec ting dung dvpx vao chan doan va dieu tri da kha phat trien, bao gom nhieu ky thuat ting dung rong rai nhat v i n la ky thuat danh dau phdng xa Ky thuat dtia vao nhting dac diem sau day: Ddng vi phdng xa va dong vi ben chiu moi qua trinh sinh ly va sinh hda nhti to chtic song Ndi mot cach khac la to chtic song tti mtic phan tti den toan c0 the hay ca quan the nhieu vi sinh vat cung khdng phan biet dtidc ddng vi ben va dvpx hoat dong sinh hoc cua minh luc dd lai eo the de ghi chung qua cac btic xa phat Khoi ltidng cac chat danh dau thtidng rat nhd va khong gay nen m o: ;u anh htidng nao den hoat dong cua td chtic sdng Cac ky thuat ap dung y hoc hat 376 nhan thtidng la khong gay thtidng ton (Non - invasive) bdi vi cao nhat cung chi la thu thuat tiem tinh mach Chat danh dau (Tracer) ly ttidng nhat can co cac dac diem sau day: - Co ti'nh chat hoan toan giong nhti do'i ttidng c i n khao sat - Chat danh dau dtidc ha'p thu hoan toan, nhanh chong va chi rieng tai cd quan, mo c i n khao sat (Target Organ) - Nong cua no it thay doi tai cho suo't qua trinh khao sat - Sau khao sat xong, no nhanh chong va hoan toan dtidc dao thai khoi cd the - Btic xa phat tti chat danh dau de dang ghi dtidc bang cac phtidng tien san co (Loai tia, nang ltidng tia) - Tao lieu ha'p thu tha'p nha't 4.1.2 Cac ung dung cua phuong phap danh dau - Tham chtic nang cac te bao, mo, cd quan hay he tho'ng cd the sdng Nghiem phap bao gom: + Chtic nang ha'p thu, chuyen hda, dao thai + Dong hoc cua cac qua trinh nhti cua he t u ln hoan, tiet nieu + Ham ltidng va nong cua cac yeu to' p h ln hoac nong cua cac hdp chat sinh hoc mot do'i ttidng khao sat nao dd nhti ham ltidng cac chat dien giai, the tich cac dich cd the, the tich mau kho'i ltidng hdng clu nong cac enzym, cac hormon mau, md Tti cac gia tri va nong dd ta cd the danh gia dtidc cac chtic nang cd ban cua td chtic song hay cd quan Cac gia tri thu dtidc cd the la cac thi, bieu do, so' xung hoac gia tri tuyet doi cua ham ltidng De thu dtidc cac nong dd cd the tting mau d tting thdi diem khac nhau, dem xung hoac hoat tinh tong cong; cd the d mau rdi (invitro) hoac tren cd the benh nhan (invivo); cd the bang nhting phep so sanh do'i chieu hoac xac dinh gia tri tuyet do'i tti cac mau - Dinh ltidng bang ky thuat mien dich phdng xa RIA va IRM A (Radio Immuno Assay va Immuno Radio Metric Assay) Thiic ky thuat cung la de danh gia va tham dd chtic nang cua cac tuyen noi tiet md hay phu tang Tuy vay cd sd khoa hoc cua ky thuat va kha nang ting dung rong rai cua no chan doan va nghien ctiu ngtidi ta tach rieng mot noi dung cua y hoc hat nhan Ngay nhieu cd sd y hoc va khoa hoc cd the chi xay dting rieng Labo RIA va IRMA de phuc vu cho cong viec cua minh Nam 1960 ky thuat djnh ltidng mien dich phdng xa (RIA) dude khdi dau b l n g Yellow va Berson vdi insulin Do phat minh ma ho dtidc giai Nobel v hoc 377 Ky thuat nav cho phep dinh ltidng den cd nanogram (10 g) va picogram (10 12g) vi tinh dac hieu rat cao cua phan ting mien dich Ngoai no cho phep tti dong hoa mau de xet nghiem hang loat + Nguyen ly cua phtidng phap Khdng nguyen du danh dau phong xa hay khong se ket hdp idi khang the dac hieu "tao phan iing mien dich vd co phiic hcfp mdi Cd sd cua ky thuat RIA la hien tiidng canh tranh giiia khdng nguyen danh dau Ag' vd khong danh clau Ag ket hdp vdi khdng the Ab Neu cho mot liidng han che Ab thi khdng nguyen khong danh dau A g (chat muon dinh liidng) mau tang, phiic hdp A g Ab danh dau se giam k, +Ag » AgAb Ab +Ag •* - A g Ab Goi phan gan Ag*Ab la phiic hdp gan (Bound=B) vd phan A g *kh on g gan la tii (free=F), B giam xuong thi phan F se tang len vd ngiidc lai Do ty le B I F co gid tri tinh toan vd dinh liidng X ac dinh ket qua bang cach so sanh vdi thi chuan md true tung la ty le cua B /F mau vd true hoanh la nong chat can xac dinh Cung co the tinh toan theo tiidng quan B I T hoac B I Bo thay cho ty le B / F vd nong Trong T la tong hoat tinh mau (B+F) vd Bo la phan gan (bound fraction) d diem cua thi (nong = 0) Ve sau ky thuat dd diidc cai tien phiidng p h ap mien dich p h on g xa khong canh tranh: Im m unioradiom etric assay (IRMAj Miller vd Hales de xiidng nam 1968 nhiing mai den nam 1980 mdi diidc iing dung rong rai lam sdng Nguyen ly cua no la Chat can dinh liidng (hormon chang han) van dong vai tro A g nhiing luc khdng cho vao mau A g * vd Ab thiidng de ket hdp fihii RIA nita md cho A b * danh dau Liidng Ab* cho that dii thiia thi hoat tinh px cua p han gan (B) Ab*Ag se ti le thuan vdi nong chat can dinh liidng Ag Ky thuat cho phep iing dung cdc Ab ddn ddng (monoclonalj nen cho cdc ket qua vdi dac hieu vd chinh xac cao hdn RIA - De thiic hien diidc ky thuat RIA hoac IRM A can cd + Chat danh dau phdng xa A g * hoac Ab* + Chat gan dac hieu: khdng the (Ab) + He thong de tach rieng phan B vd F + Chat can dinh liidng de lap thi chuan Nhii vay khau quan md mot labo rieng phai tit lam diidc l a t a o Ab* hoac Ag* vd Ab dac hieu (Antiserum chiia Ab dac hieu ddi vdi A g nhdt dinh nao do) 378 Hien ky thuat dd ditdc dp dung rong rdi lam sdng va d phdng thi nghiem - Ghi hinh phong xa Viec the hien bang hinh anh (ghi hinh) biic xa phat tti cac mo, phu tang va ton thtidng cd the benh nhan de danh gia sti phan bo" cac dtidc chat phong xa danh d lu d cung cang tot hdn nhd vao cac tien bo cd hoc va dien tti, tin Co nhieu ky thuat ghi hinh phong xa : ghi hinh vach thang, chup nhap nhay (gamm camera), chup cat ldp bang ddn photon (SPECT - Single Photon Emission Computerized Tomography) va chup cat ldp bang positron (PET - Positron Emission Tomography) Hinh 10.38 Tren xa hinh tuyen giap co vung khong bat iod phong xa d day va giura thuy phai (nhan lanh) nang tuyen giap Hinh 10.39 Xa hinh toan than vdi MDP danh dau Tc-99m a benh nhan bi ung thti xi/dng (osteocarcinoma) da di can vao phoi Benh nhan da bi thao khdp hang chi di/di ben trai 4.2 Phtidng phap dung nguon chieu xa 4.2.1 Dung nguon chieu de chan doan benh Vdi sti chieu tia tao cac phan ting hat nhan thich hdp cung co the coi ky thuat dinh ludng kich hoat bang Neutron (Neutron Activization Analysis) la mot ky thuat y hoc hat nhan bdi vi bang ky thuat chung ta co the dinh ltidng cac yeu to vi da ltidng cac mau sinh hoc (mau da toe ) de chan doan benh Nguyen ly cua ky thuat la co the bien mot dong vi ben dong vi phong xa bang cach ban cac Neutron thich hdp vao hat nhan cua dong vi ben Ngtidi ta xac dinh ham ltidng dong vi ben bang cach dem phong xa phat tti dong vi phong xa mdi dtidc tao sau chieu Neutron Vi du: !5Mn (n.y) 5(1 Mn 379 hay 16 O (n, P) 16 X do: 03 Mn, lb0 la nhiing dong vi ben (dong vi me) N la nhUng dong vi phong xa (dong vi con) Mn va Tat nhien hoat tfnh phong xa thu dUdc phu thuoc nhieu veu to nhti: - Nong cua dong vi me co mau Thong liidng va dac diem cua chum Xeutron - Tiet dien cua hieu iing - Thdi gian chieu Khi chieu neutron vao mau co the xay nhieu loai phan iing va co nhieu dong vi phong xa diidc tao Vi vay can phai phan tach tinh sach bang cac ky thuat hoa hoc va vat ly khac Tuy vay no cho phep xac dinh rat chinh xac nhiing yeu to vi liidng cd the nhii: Fe Sc, Zn, Rb, Mn Cr Co Cu Cs K, Th, Au, Mg, Na, Br, As, I hoac nhiing yeu to da liidng nhii C, O, X Ca cd the Til co the chan doan duoc nhieu benh khac ve roi loan chuyen hoa, hap thu, tim mach, tieu hoa, tam than 4.2.2 Dung nguon chieu dieu tri Mot iing dung niia y hoc hat nhan la tac dung sinh hoc cua tia phong xa dUdc hap thu vao to chiic sinh hoc X g ay til dau ngUdi ta da thay ro tac dung diet te bao cua biic xa ion hoa va da sii dung no nhieu phan nganh khac cua sinh hoc va y hoc (diet khuan va diet te bao benh) Vdi nhiing hieu biet cang sau sac ve cd che truyen nang liidng, cd che diet bao, cac dac diem vat ly cua biic xa, cac yeu to’ anh hiidng cua moi triidng (nhiet do, nong oxy ) cang co nhieu cai tien ve ky thuat xa tri Day la sii dung tac dung sinh hoc cac biic xa ion hoa len cac mam benh, te bao benh No cung tao nhiing Idi fch thiet thiic va luon luon doi mdi y hoc Chung bao gom: - Dieu tri chieu ngoai (Teletherapy) Vdi viec sii dung cac tia X, tia gamma ciing va ca cac may gia to’c de diet cac te bao ung thu - Dieu tri ap sat (Brachytherapy) Bao gom ca ludi dao gamma (Gamma knife), cac nguon kin (kim hat ) va nguon hd (Applicator) su dung cac dong vi phong xa phat beta cung hoac gamma mem No bao gom ca ky thuat ddn gian de dieu tri benh ngoai da hoac ky thuat phUc tap nhu dua ca nguon 9uY vao khoi u tuyen yen hay ket hop vdi phau thuat de dua cac nguon xa kin vao tan cac hoc tii nhien Ky thuat dieu tri ap sat da dUdc cai tien rat nhieu lam xuat hien cac phudng phap mdi nhu dieu tri nap nguon sau (After Loading Therapy), lap ke hoach dieu tri theo kich thudc khoi u (Dim entional Treatm ent Planing) hoac dung thiet bi dat tien (Gam m a Knife) de chua cac benh ve mach mau hop so Ngoai cac dong vi phong xa co dien nhu 222Ra, c°Co 90Y r.euoi ta dung nhieu dong vi phong xa mdi dieu tri ap sat nhu Palludiurr - 107 Samarium - 145 Am ericum - 241 Y te rb n u m - 169 380 - Dieu tri bang cdc nguon hd (Curietherapy) Day thac sti la mot biidc tien dai va lam thay doi ve ban chat ky thuat xa tri Diia vao cac hoat ti'nh chuyen hoa binh thiidng (te bao tuyen giap hap thu lode) hoac thay doi benh ly (kho’i ung thii hap thu nhiing phan tii hiiu cd dac hieu) ngiidi ta cho cac nguon hd phong xa vao den cac to chiic dich (Target Tissue) bj benh de dieu tri Cac dong vi phong xa diidc diia vao cac to chiic dich nhd vao qua trinh cd hoc nhii diia vao phe quan va phoi nhd sii thong (Ventilation), vao da day (nhd dong tac nuo’t), vao cac te bao mau (nhd tuan hoan mau) B ln g cac nguon phong xa h6 thich hdp chung ta co the dieu tri diidc mot so" benh tuyen giap, benh mau, cd xiidng khdp, tac mach vanh va nhieu benh ung thii ciing di can cua no 4.2.3 Mot so muc dich khac cua chieu xa Viec ap dung cac nguon chieu xa nganh sinh hoc co the dat mot cac muc dich sau day: - Tieu diet cdc nam, moc, vi sinh vat gay hai: Liidng thiic, thiic pham co the bj hu hong, kem pham chat thdi gian cat giti, nhat la d vung nhiet ddi Nhin chung, sti hao hut bao quan thtidng la 5% va co len den 60% Khong phai ltic nao chung ta cung xii ly dtidc bang nhiet vdi khoi ltidng ldn Dting hoa chat co khong co ket qua va co the gay tac dung xau cho ngtidi sti dung cac ltidng thtic, thtic pham Chieu xa la de tieu diet nam, moc, vi sinh vat, sau bo gay hti hong ltidng thtic, thtic pham Muon vay phai dung nhting lieu rat ldn Cac nghien ctiu cho thay lieu 5.000 h- 15.000 R co the han che sti sinh trtidng cua sau bo, lieu 20.000 R co the giet chet ca trting sau Lieu ltidng dung trtidc het phu thuoc vao loai vi khuan va moi trtidng chieu xa Vdi nhting lieu ldn nhti vay ngtidi ta phai quan tam den hau qua xay sau chieu xa ltidng thtic thtic pham Lieu co sti phan huy va lam giam chat ltidng dinh dtidng hoac lam xuat hien nhting chat doc hai mdi chieu xa khong? Qua nhieu lan thi nghiem, ngtidi ta thay vdi lieu 7.000 -h 10.000 R co the bao quan khoai tav lau ngav khong mam va cung khong gay hai cho stic khoe ngtidi sii dung Khoai tay mam la qua trinh tong hdp acid nhan d nhting diem sinh trtidng Viec chieu xa co the lam cham qua trinh tong hdp lai Doi vdi trting gay hai, ngoai viec tieu diet ban than trung bang tia xa, ngtidi ta muon tao nhting thuoc tinh di truyen bat Idi nhti gay vo sinh cho trung dtic roi tung chting vao moi trtidng chung sinh song Ky thuat co nhieu Idi ich vi vdi lieu khoang 8.000 R co the lam dtic mat kha nang sinh san, tao nhting trting ung va do sau mot thdi gian, ca tap hop trting bj diet vong Tti trtidc tdi nay, thtidng khti trting dung cu y te chi khau thuoc vaccin bang hoa chat (thuoc sat trting tay rtia, ) va nhiet nang (luoc hap, say dot ) Cac cach sti ly khong phai luc nao cung ap dung dude va co the lam hti hong mot phan hoac toan bo san pham Tti sau dai ehien the gidi lan thti hai, ngtidi ta ap dung rong rai viec dting btic xa ion hoa de tieu diet cac vi sinh vat d cac san pham y te da neu d tren Ngay nay, nhieu loai thuoc gang tay phau 381 thu^t, dung cu tiem truyen, dung cu phau thu&t dtidc xuat xtidng sau ap dung viec khii trung bang biic xa ion hoa Thuc viec xac dinh cai chet cua vi sinh vat d day rat kho Thong thtidng, chi co the kiem tra sti "vo trung" cua san p h im ma thoi Lay nhting mau vat cua san pham, u nhiet thuan Idi cho sti phat trien cua vi khuan