Download - Computed Tomography HU

7/25/2019 Computed Tomography HU

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TUGAS ILMU BEDAH SARAF

HOUNSFIELD UNIT

Disusun Oleh: Christina Agustin

NIM: 11.2014.137

Pembimbing :

dr. Fadhil, Sp.BS

KEPANITERAAN KLINIK ILMU BEDAH STASE BEDAH UROLOGI

RUMAH SAKIT UMUM DAERAH TARAKAN

PERIODE 2 !ULI 2"#$ % & OKTOBER 2"#$

FAKULTAS KEDOKTERAN

UNI'ERSITAS KRISTEN KRIDA (A)ANA

!AKARTA

2"#$


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)*m+u,e- ,*m*g./+h0

Dr Henry Knipeand Ass. r. !ir"an !. #adrl"ans$iet al.

)*m+u,e- ,*m*g./+h0%C&' s(anning, als) $n)*n as 1*m+u,e.ie- /3i/l

,*m*g./+h0%)AT' s(anning, is a diagn)sti( i+aging pr)(edure that uses-rays in )rder t)

present (r)ss-se(ti)nal i+ages %sli(es' )/ the )dy. Cr)ss se(ti)ns are re()nstru(ted /r)+

the +easure+ents )/ attenuati)n ()e//i(ients )/ -ray ea+s in the )lu+e )/ the )"e(t

studied.

C& is ased )n the /unda+ental prin(iple that the density )/ the tissue passed y the -ray

ea+ (an e +easured /r)+ the (al(ulati)n )/ the attenuati)n ()e//i(ient.

S), C& all)*s the re()nstru(ti)n )/ the density )/ the )dy, y t*) di+ensi)nal se(ti)n

perpendi(ular t) the ais )/ the a(uisiti)n syste+.

&he e+itter )/ -rays %typi(ally *ith energy leels et*een 20 and 10 $e5', e+its #

ph)t)ns %+)n)(hr)+ati(' per unit )/ ti+e. &he ea+ passes thr)ugh the layer )/ i)l)gi(al

+aterial )/ thi($ness delta . A dete(t)r pla(ed at the eit )/ the sa+ple, +easures # 6 delta#

ph)t)ns, delta # s+aller than 0. S), the -rays intera(ted *ith the )"e(t and the ea+ hae

een attenuated.

&here are asi(ally t*) pr)(esses )/ the as)rpti)n theph)t)ele(tri( e//e(tand theC)+pt)ne//e(t. &his phen)+en)n is represented y a single ()e//i(ient +"u.

8n the spe(i/i( (ase )/ the C&, the e+itter )/ -rays r)tates ar)und the patient and the

dete(t)r, pla(ed in dia+etri(ally )pp)site side, pi($s up the i+age )/ a )dy se(ti)n %ea+

and dete(t)r +)e in syn(hr)ny'.

9nli$e -ray radi)graphy, the dete(t)rs )/ the C& s(anner d)es n)t pr)du(e an i+age. &hey

+easure the trans+issi)n )/ a thin ea+ %1-10++' )/ -rays thr)ugh a /ull s(an )/ the )dy.

&he i+age )/ that se(ti)n is ta$en /r)+ di//erent angles and this all)*s t) retriee the

in/)r+ati)n )n the depth %in the third di+ensi)n'.

8n )rder t) )tain t)+)graphi(i+ages )/ the patient /r)+ the data in ra* s(an, the

()+puter uses ()+ple +athe+ati(al alg)rith+s /)r i+age re()nstru(ti)n.

8/ the -ray at the eit )/ the tue is +ade +)n)(hr)+ati( )r uasi-+)n)(hr)+ati( *ith the

pr)per /ilter, )ne (an (al(ulate theattenuati)n ()e//i(ient ()rresp)nding t) the )lu+e )/

irradiated tissue y the appli(ati)n )/ the general /)r+ula )/ as)rpti)n )/ the -rays in the

/ield %see Figure 1'.
http://radiopaedia.org/users/henryknipehttp://radiopaedia.org/users/miskohttp://radiopaedia.org/articles/missing?article%5Btitle%5D=xrayshttp://radiopaedia.org/articles/missing?article%5Btitle%5D=xrayshttp://radiopaedia.org/articles/attenuation-coefficienthttp://radiopaedia.org/articles/photoelectric-effecthttp://radiopaedia.org/articles/compton-effecthttp://radiopaedia.org/articles/compton-effecthttp://radiopaedia.org/articles/missing?article%5Btitle%5D=tomographichttp://radiopaedia.org/articles/attenuation-coefficienthttp://radiopaedia.org/articles/attenuation-coefficienthttp://radiopaedia.org/users/miskohttp://radiopaedia.org/articles/missing?article%5Btitle%5D=xrayshttp://radiopaedia.org/articles/attenuation-coefficienthttp://radiopaedia.org/articles/photoelectric-effecthttp://radiopaedia.org/articles/compton-effecthttp://radiopaedia.org/articles/compton-effecthttp://radiopaedia.org/articles/missing?article%5Btitle%5D=tomographichttp://radiopaedia.org/articles/attenuation-coefficienthttp://radiopaedia.org/articles/attenuation-coefficienthttp://radiopaedia.org/users/henryknipe


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&he )utg)ing intensity 8%' )/ the ea+ )/ ph)t)ns +easured *ill depend )n the l)(ati)n. 8n

/a(t, 8%' is s+aller *here the )dy is +)re radi))paue.

H)uns/ield (h)se a s(ale that a//e(ts the /)ur asi( densities, *ith the /)ll)*ing alues

Air : - 1000

Fat : -;0 t) -120

)d/rey H)uns/ield;

, a #)el pri?e*inner /)r his *)r$ in 1@7@, related the linear attenuati)n ()e//i(ient )/ a l)(ali?ed regi)n
http://radiopaedia.org/articles/attenuation-coefficienthttp://radiopaedia.org/articles/attenuation-coefficienthttp://radiopaedia.org/articles/missing?article%5Btitle%5D=digital-imagehttp://radiopaedia.org/articles/missing?article%5Btitle%5D=pixelhttp://radiopaedia.org/articles/missing?article%5Btitle%5D=voxelhttp://radiopaedia.org/articles/missing?article%5Btitle%5D=filtered+back+projectionhttp://radiopaedia.org/articles/hounsfield-unitshttp://radiopaedia.org/articles/hounsfield-unitshttp://radiopaedia.org/articles/godfrey-hounsfieldhttp://radiopaedia.org/articles/godfrey-hounsfieldhttp://radiopaedia.org/articles/attenuation-coefficienthttp://radiopaedia.org/articles/missing?article%5Btitle%5D=digital-imagehttp://radiopaedia.org/articles/missing?article%5Btitle%5D=digital-imagehttp://radiopaedia.org/articles/missing?article%5Btitle%5D=pixelhttp://radiopaedia.org/articles/missing?article%5Btitle%5D=voxelhttp://radiopaedia.org/articles/missing?article%5Btitle%5D=voxelhttp://radiopaedia.org/articles/missing?article%5Btitle%5D=filtered+back+projectionhttp://radiopaedia.org/articles/hounsfield-unitshttp://radiopaedia.org/articles/godfrey-hounsfield


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*ith the attenuati)n ()e//i(ient )/ *ater, the +ultipli(ati)n /a(t)r )/ 1000 is used /)r C&

nu+er integers.

S), the signal trans+itted y the dete(t)r is pr)(essed y the C in the /)r+ )/ the digital

in/)r+ati)n, the C& i+age re()nstru(ti)n.

Prinsip CT-Scan:

Sinar adalah pan(aran gel)+ang ele$tr)+agneti$ yang se"enis dengan gel)+ang radi),

panas, (ahaya, dan sinar ultrai)let, tetapi dengan pan"ang gel)+ang yang sangat pende$.

Karena pan"ang gel)+ang yang sangat pende$ itu, +a$a sinar dapat +ene+us enda-

enda. ada C&, $)+puter di$erah$an untu$ +engganti$an peranan /il+-$aset dan peranan

$a+ar gelap dengan (airan-(airan developerserta /i$sirnya seperti pada /)t) sinar iasa.

&aung ntgen dan $u+pulan dete$t)r erada dala+ suatu *adah yang diseutgantry. Di

tengah-tengah gantry tersedia luang, yang er/ungsi untu$ dapat +e+asu$$an atau

+enggeser +e"a eserta pasien dengan +)t)r.

!ulai pesa*at C& generasi $etiga, gantry dapat di+iring$an $e ela$ang atau $e depan,

+asing-+asing +a$si+al sa+pai 200, sehingga tida$ hanya pena+pang tega$ sa"a yang dapat

diuat, +elain$an "uga scan+iring dengan sudut yang di$ehenda$i. Bai$ taung ntgen

+aupun dete$t)r-dete$t)r ergera$ +e+utari pasien seagai )ye$ yang dite+pat$an

diantaranya, 3;00. Sela+a ergera$ +e+utar itu, taung +enyinari pasien dan +asing-

+asing dete$t)r +enang$ap sisa-sisa sinar yang telah +ene+us pasien, seagai+ana

tugas /il+ iasa. Se+ua data se(epat $ilat di$iri+ $e $)+puter yang +eng)lahnya

%+enger"a$an $al$ulasi' se(epat $ilat pula. Hasil peng)lahan +un(ul dala+ layer &5 yang

e$er"a seagai +)nit)r. Hasilnya +erupa$an pena+pang agian tuuh yang diputari itu dan

diseutscan.

rinsip $er"a C&-S(an hanya dapat +en-s(anning tuuh dengan irisan +elintang %p)t)ngan

aial'. #a+un dengan +e+an/aat$an te$n)l)gi $)+puter +a$a ga+aran aial yang telah

didapat$an dapat di/)r+at $e+ali sehingga didapat$an ga+aran ()r)nal, sagital, )liue,

diag)nal ah$an entu$ tiga di+ensi dari )"e$ terseut. Suatu s$ala untu$ +engu$ur

$)e/isien atenuasi "aringan pada C& diseut Hounsfield Unit %H9'. Hounsfield Unit "uga

sering diseut seagai CT numbers.


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&ael 1. C)nt)h CT numbersdari Beragai aringan

!/.ing/n CT Numbers4HU5

&ulang 1000

Hepar 40-;0

White Matter 20-30

rey Matter 37-4

Darah 40

t)t 10-40

>in"al 30

Cairan Serer)spinal 1

Air 0

Ee+a$ -0-%-100'

9dara -1000

e/eren(es

1. >)ld+an E


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&he H*uns6iel- uni, 4HU5 is a uantity ()++)nly used in ()+puted t)+)graphy

%C&'s(anning t) epress C& nu+ersin a standardised and ()nenient /)r+. H)uns/ield

units, (reated y and na+ed a/ter Sir >)d/rey H)uns/ield, are )tained /r)+ a linear

trans/)r+ati)n )/ the +easured attenuati)n ()e//i(ients1. &his trans/)r+ati)n %/igure 1' is

ased )n the aritrary de/initi)ns )/ air and *ater

radi)density )/ distilled *ater at standard te+perature and pressure %S&' : 0 H9

radi)density )/ air at S& : -1000 H9

H)uns/ield units are +easured and rep)rted in a ariety )/ (lini(al appli(ati)ns. ne *ell

$n)*n use is the ealuati)n )/ the /at ()ntent )/ the lier, *ith /atty lier diagn)sed y the

presen(e )/ a lier-t)-spleen rati) less than 1.0 )r 0. 2. ther less ()++)n uses in(lude

assessing)ne +ineral density%B!D' 3, predi(ting the presen(e )/ ane+ia 4, and guiding the

+anage+ent )/ $idney st)nes.

e/eren(es

1.H)uns/ield >#. C)+puted +edi(al i+aging. #)el le(ture, De(e+er , 1@7@.

C)+put Assist &)+)gr. 1@0I4 %' ;;-74. u+ed (itati)n

2. Je 8, Ei D, #asir K et-al. C)+puted t)+)graphy s(ans in the ealuati)n )/ /atty

lier disease in a p)pulati)n ased study the +ulti-ethni( study )/ ather)s(ler)sis. A(ad

adi)l. 2012I1@ %7' 11-. d)i10.101;".a(ra.2012.02.022-Free tet at

pu+ed- u+ed (itati)n

3. i($hardt , ))ler BD, Eauder & et-al. pp)rtunisti( s(reening /)r

)ste)p)r)sis using ad)+inal ()+puted t)+)graphy s(ans )tained /)r )ther

indi(ati)ns. Ann. 8ntern. !ed. 2013I1 %' [email protected])i10.732;0003-41@-1--

2013041;0-00003- Free tet at pu+ed- u+ed (itati)n

4.Bruni S>, ata/i) F!, Du/t)n A et-al. &he assess+ent )/ ane+ia /r)+

attenuati)n alues )/ (ranial en)us drainage )n unenhan(ed ()+puted t)+)graphy )/
http://radiopaedia.org/articles/computed-tomographyhttp://radiopaedia.org/articles/computed-tomographyhttp://radiopaedia.org/articles/godfrey-hounsfieldhttp://radiopaedia.org/articles/attenuation-coefficienthttp://radiopaedia.org/articles/bone-mineral-densityhttp://radiopaedia.org/articles/urolithiasishttp://www.ncbi.nlm.nih.gov/pubmed/6997341http://dx.doi.org/10.1016/j.acra.2012.02.022http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3377794http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3377794http://www.ncbi.nlm.nih.gov/pubmed/22521729http://dx.doi.org/10.7326/0003-4819-158-8-201304160-00003http://dx.doi.org/10.7326/0003-4819-158-8-201304160-00003http://dx.doi.org/10.7326/0003-4819-158-8-201304160-00003http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3736840http://www.ncbi.nlm.nih.gov/pubmed/23588747http://radiopaedia.org/articles/computed-tomographyhttp://radiopaedia.org/articles/computed-tomographyhttp://radiopaedia.org/articles/godfrey-hounsfieldhttp://radiopaedia.org/articles/attenuation-coefficienthttp://radiopaedia.org/articles/bone-mineral-densityhttp://radiopaedia.org/articles/urolithiasishttp://www.ncbi.nlm.nih.gov/pubmed/6997341http://dx.doi.org/10.1016/j.acra.2012.02.022http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3377794http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3377794http://www.ncbi.nlm.nih.gov/pubmed/22521729http://dx.doi.org/10.7326/0003-4819-158-8-201304160-00003http://dx.doi.org/10.7326/0003-4819-158-8-201304160-00003http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3736840http://www.ncbi.nlm.nih.gov/pubmed/23588747


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the head. Can Ass)( adi)l . 2013I;4 %1' 4;-

0.d)i10.101;".(ar".2011.0.00- u+ed (itati)n

.u?aid 8, Al-ahtani S, D)+iniue S et-al. A @70 H)uns/ield units %H9'

thresh)ld )/ $idney st)ne density )n n)n-()ntrast ()+puted t)+)graphy %#CC&'

i+pr)es patientsL sele(ti)n /)r etra()rp)real sh)($*ae lith)tripsy %=S