CT REGISTRY- STUDY THIS AND YOU'LL
PASS!! (EXCLUDING ANATOMY) 100%
GUARANTEED
how ydo yyou yreduce ybeam yhardening y- ycorrect yanswers y-1. yIncrease ydose
2. yReduce ycollimation--Reduce yslice ythickness
3. yIncrease ywindow ywidth
At ywhat ylevel ydoes ythe yabdominal yaortal ybifurcate? y- ycorrect yanswers y-L4
What yis ythe ytypical yscan ydelay yafter yinjection yof ycontrast ymedia yfor ystudies yof
ythe yliver? y- ycorrect yanswers y-30-45 yseconds
What ywindow ysettings yprovide ythe ybest ytissue ydifferentiation ywithin ythe yliver? y-
ycorrect yanswers y-window ywidth= y140, ylevel= y60
What yis ythe ywindow ysettings ythat yprovide ythe ybest ybone ywindow yfor ythe ypelvis?
y- ycorrect yanswers y-window ywidth=2000, ywindow ylevel=350
,What ymAs yis ytypically yused yin yroutine yCT yexams yof ythe yabdomen? y- ycorrect
yanswers y-200-300 ymAs
What yis ythe yresult yof ythe ybifurcation yof ythe yabdominal yaorta? y- ycorrect yanswers
y-The yright yand yleft ycommon yiliac yarteries
What yis ythe yanode ytarget yangle? y- ycorrect yanswers y-12 ydegrees
At ywhat ylevel ydo ythe ycommon ycarotids ybifurcate yinto ythe yinternal yand yexternal
ycarotid yarteries? y- ycorrect yanswers y-C3-C4
The yfloor yof ythe yorbit yis yformed yby ythe y__________ ybones. y- ycorrect yanswers y-
maxillary yand yzygomatic
The ylateral ywall yof ythe yorbit yis yformed yby ythe y___________ ybones. y- ycorrect
yanswers y-zygomatic yand ysphenoid
The ymedial ywall yof ythe yorbit yis yformed yby ythe y_________ ybones. y- ycorrect
yanswers y-ethmoid yand ylacrimal ybones
how ydo yyou ycalculate yeffective ymAs? y- ycorrect yanswers y-mAs/pitch
define ywindow ylevel yand ywindow ywidth y- ycorrect yanswers y-LEVEL: ya ychosen
ymidpoint yin ythe ygrayscale y
WIDTH: ynumber yof ygrayscale yvalues yabove yand ybelow ythe ylevel. y
- yThe ywidth yis yDIVIDED yin yHALF yand ydistributed yabove yand ybelow ythe ylevel. y
- yAnything yabove ythe ywindow yis ywhite
- yAnything ybelow ythe ywindow yis yblack
The ywider ythe ywindow ythe ymore ygrayscale yvalues, ythe ylower ythe ycontrast!
example:
Level y100, yWidth y300
White y= y>+250
Black y= y<-50
Level y100, yWidth y200
White y= y>+200
Black y= y<0
Level y100, yWidth y150
White y= y>+175
Black y= y<25
,factors ythat yaffect yspatial yand ycontrast yresolution y- ycorrect yanswers y-Spatial
yresolution:
1) yfocal yspot
2) ydetector ywidth y(aperture)
3) yreconstruction yalgorithm y- ybone>soft ytissue
4) yslice ythickness y- ythinner yis ybetter
5) ypixel/FOV/matrix
6) ypitch y- ydecreased ypitch ymeans yno ygaps
7) ynyquist ylimitations
Contrast yresolution: yCNR
1) yenergy yof yX-rays y- ykVp y- y↑ ykVp y↓ ycontrast
2) ynumber yof yX-rays y- ymA y- y↑ ymA y↓ ymottle
3) yslice ythickness y- ythicker yis ybetter
4) yreconstruction ymethod y- yiterative y> yfiltered
5) yreconstruction yalgorthith y- ysoft ytissue>bone
Give ywindow ylevels yfor ybrain, ylung, yabdomen, ybone y- ycorrect yanswers y-Brain:
yW80,L+40
Lung: yW1500, yL-400
Abdomen: yW400, yL+50
Bone: yW1600, yL+500
What yis ybeam yhardening?
what yare ythe ytwo ytypes yof ybeam yhardening yartifact?
how ydo yyou ycompensate yfor yit? y- ycorrect yanswers y-1) yas ythe yX-ray ybeam
ypasses ythrough yan yobject, ylower yenergy yphotons yare yremoved y(like yfiltration!)
yleaving ya y"harder ybeam" yof yhigh yenergy yphotons. yThis ycauses ytwo yartifacts:
2) yCupping: ythe ycenter yof ya yround yobject yis ydarker ythan ythe yperiphery ydue yto
yhardening yof ythe ybeam y360 ydegrees yaround ythe yobject. yhappens yin ythe yhead
3) yStreak: ythese yare ydark ybands ythat yoccur yin ybetween ytwo ydense yobjects y-
ynearly yall ythe yphotons yare yremoved yin ya yline ybetween ythe ytwo yobjects
4) yfixes:
A) yFiltration: ypre-hardening ythe ybeam yto yremove ylow yenergy yphotons
B) yCalibration: yusing ya yphantom yto yset ya ycompensated ymA/kVp
C) yCorrect ysoftware: yiterative yreconstruction ymay yhelp
D) yAvoidance: ytilting ythe ygantry yof ypositioning ythe ypatient yto yavoid yareas ythat
ymay ycause yhardening.
ring yartifact y- ycorrect yanswers y-Calibration yerror yor ydefective ydetector ycause
yconsistently yerroneous yreading yat yeach yangular yposition, yresulting yin ya ycircular
yartifact
, is ythe yfocal yspot ylarge yor ysmall? y- ycorrect yanswers y-large y0.6-1.2 y- yso yas ynot yto
yoverheat ythe yanode yfrom ysuch ya yhigh ymA
Which yof ythe yfollowing ywill yresult yin yan yincreased yvoxel ysize: yB yincreased yslice
ythickness y- ycorrect yanswers y-A)decreased yreconstruction yFOV yB) yincreased yslice
ythickness yC) yincreased ymatrix yD) ynone yof ythese
If ya ytissue ywith ya yCT ynumber yof y+300 yappears ywhite yon ythe yimage, ywhich yof
ythe yfollowing yare ythe ywindow ywidth yand ywindow ylevel yselected: yA)window ylevel
y=0, ywindow ywidth y=500 yB)window ylevel= y+300, ywindow ywidth= y500 yC)window
ylevel y=+100, ywindow ywidth y=1000 yD)none yof ythese y- ycorrect yanswers y-A)
ywindow ylevel y=0, ywindow ywidth y=500
What yis ythe yvolume yof ya yvoxel yif ya yslice ythickness yof y3 ymm, ya y512x512 ymatrix
y& ya yreconstruction yfield yof yview yof y25.6cm yare yused yA) y0.75mm³ yB)1.5mm³ yC)
y6.0mm³ yD)none yof ythese y- ycorrect yanswers y-A. ySolve ythis yby yfinding ythe ypixel
ysize yfirst yFOV/matrix ysize y... ythat yis y0.5 y... ynow ysquare ythat y0.25 y.... ymultiply
ythat yby yslice ythickness yand yyou yget y0.75
Which yof ythe yfollowing yparameters yis yresponsible yfor ypartial yvolume yaveraging: yA)
ymatrix ysize yB) ykVp yC)slice ythickness yD) ypatient ydose y- ycorrect yanswers y-C
Voxel yequation y- ycorrect yanswers y-pixel yarea yx ysection ythickness
What yis yinterpolation? y- ycorrect yanswers y-Mathematical ymethod yfor ytaking
ySPIRAL ydata yand yviewing yit yas yAXIAL yimages
Bone ywindows y- ycorrect yanswers y-2000-4000 yWW
200-400 yWL
Lung ywindows y- ycorrect yanswers y-1400-1600 yWW
(-)400-600 yWL
Modular yTransfer yFunction? y- ycorrect yanswers y-graphical yrepresentation yof
ySPATIAL yRESOLUTION ymeasured yin ylp/cm, ytells yhow ysmall yyou ycan yscan
ywithout yblurring
Decrease ypartial yvolume yaveraging? y- ycorrect yanswers y-Reduce yslice ythickness
Which yportion yof ythe ypancreas yis ythe ymost ycommon ysite yfor ytumors?; yand ywhere
ylocated? y- ycorrect yanswers y-The yhead yof ythe ypancreas. yIt yis ylocated
yapproximately yat yT12
LUNG yWINDOW
(-) yIS yAIR y- ycorrect yanswers y-2000 yWW yand y-200 yWL y=
PASS!! (EXCLUDING ANATOMY) 100%
GUARANTEED
how ydo yyou yreduce ybeam yhardening y- ycorrect yanswers y-1. yIncrease ydose
2. yReduce ycollimation--Reduce yslice ythickness
3. yIncrease ywindow ywidth
At ywhat ylevel ydoes ythe yabdominal yaortal ybifurcate? y- ycorrect yanswers y-L4
What yis ythe ytypical yscan ydelay yafter yinjection yof ycontrast ymedia yfor ystudies yof
ythe yliver? y- ycorrect yanswers y-30-45 yseconds
What ywindow ysettings yprovide ythe ybest ytissue ydifferentiation ywithin ythe yliver? y-
ycorrect yanswers y-window ywidth= y140, ylevel= y60
What yis ythe ywindow ysettings ythat yprovide ythe ybest ybone ywindow yfor ythe ypelvis?
y- ycorrect yanswers y-window ywidth=2000, ywindow ylevel=350
,What ymAs yis ytypically yused yin yroutine yCT yexams yof ythe yabdomen? y- ycorrect
yanswers y-200-300 ymAs
What yis ythe yresult yof ythe ybifurcation yof ythe yabdominal yaorta? y- ycorrect yanswers
y-The yright yand yleft ycommon yiliac yarteries
What yis ythe yanode ytarget yangle? y- ycorrect yanswers y-12 ydegrees
At ywhat ylevel ydo ythe ycommon ycarotids ybifurcate yinto ythe yinternal yand yexternal
ycarotid yarteries? y- ycorrect yanswers y-C3-C4
The yfloor yof ythe yorbit yis yformed yby ythe y__________ ybones. y- ycorrect yanswers y-
maxillary yand yzygomatic
The ylateral ywall yof ythe yorbit yis yformed yby ythe y___________ ybones. y- ycorrect
yanswers y-zygomatic yand ysphenoid
The ymedial ywall yof ythe yorbit yis yformed yby ythe y_________ ybones. y- ycorrect
yanswers y-ethmoid yand ylacrimal ybones
how ydo yyou ycalculate yeffective ymAs? y- ycorrect yanswers y-mAs/pitch
define ywindow ylevel yand ywindow ywidth y- ycorrect yanswers y-LEVEL: ya ychosen
ymidpoint yin ythe ygrayscale y
WIDTH: ynumber yof ygrayscale yvalues yabove yand ybelow ythe ylevel. y
- yThe ywidth yis yDIVIDED yin yHALF yand ydistributed yabove yand ybelow ythe ylevel. y
- yAnything yabove ythe ywindow yis ywhite
- yAnything ybelow ythe ywindow yis yblack
The ywider ythe ywindow ythe ymore ygrayscale yvalues, ythe ylower ythe ycontrast!
example:
Level y100, yWidth y300
White y= y>+250
Black y= y<-50
Level y100, yWidth y200
White y= y>+200
Black y= y<0
Level y100, yWidth y150
White y= y>+175
Black y= y<25
,factors ythat yaffect yspatial yand ycontrast yresolution y- ycorrect yanswers y-Spatial
yresolution:
1) yfocal yspot
2) ydetector ywidth y(aperture)
3) yreconstruction yalgorithm y- ybone>soft ytissue
4) yslice ythickness y- ythinner yis ybetter
5) ypixel/FOV/matrix
6) ypitch y- ydecreased ypitch ymeans yno ygaps
7) ynyquist ylimitations
Contrast yresolution: yCNR
1) yenergy yof yX-rays y- ykVp y- y↑ ykVp y↓ ycontrast
2) ynumber yof yX-rays y- ymA y- y↑ ymA y↓ ymottle
3) yslice ythickness y- ythicker yis ybetter
4) yreconstruction ymethod y- yiterative y> yfiltered
5) yreconstruction yalgorthith y- ysoft ytissue>bone
Give ywindow ylevels yfor ybrain, ylung, yabdomen, ybone y- ycorrect yanswers y-Brain:
yW80,L+40
Lung: yW1500, yL-400
Abdomen: yW400, yL+50
Bone: yW1600, yL+500
What yis ybeam yhardening?
what yare ythe ytwo ytypes yof ybeam yhardening yartifact?
how ydo yyou ycompensate yfor yit? y- ycorrect yanswers y-1) yas ythe yX-ray ybeam
ypasses ythrough yan yobject, ylower yenergy yphotons yare yremoved y(like yfiltration!)
yleaving ya y"harder ybeam" yof yhigh yenergy yphotons. yThis ycauses ytwo yartifacts:
2) yCupping: ythe ycenter yof ya yround yobject yis ydarker ythan ythe yperiphery ydue yto
yhardening yof ythe ybeam y360 ydegrees yaround ythe yobject. yhappens yin ythe yhead
3) yStreak: ythese yare ydark ybands ythat yoccur yin ybetween ytwo ydense yobjects y-
ynearly yall ythe yphotons yare yremoved yin ya yline ybetween ythe ytwo yobjects
4) yfixes:
A) yFiltration: ypre-hardening ythe ybeam yto yremove ylow yenergy yphotons
B) yCalibration: yusing ya yphantom yto yset ya ycompensated ymA/kVp
C) yCorrect ysoftware: yiterative yreconstruction ymay yhelp
D) yAvoidance: ytilting ythe ygantry yof ypositioning ythe ypatient yto yavoid yareas ythat
ymay ycause yhardening.
ring yartifact y- ycorrect yanswers y-Calibration yerror yor ydefective ydetector ycause
yconsistently yerroneous yreading yat yeach yangular yposition, yresulting yin ya ycircular
yartifact
, is ythe yfocal yspot ylarge yor ysmall? y- ycorrect yanswers y-large y0.6-1.2 y- yso yas ynot yto
yoverheat ythe yanode yfrom ysuch ya yhigh ymA
Which yof ythe yfollowing ywill yresult yin yan yincreased yvoxel ysize: yB yincreased yslice
ythickness y- ycorrect yanswers y-A)decreased yreconstruction yFOV yB) yincreased yslice
ythickness yC) yincreased ymatrix yD) ynone yof ythese
If ya ytissue ywith ya yCT ynumber yof y+300 yappears ywhite yon ythe yimage, ywhich yof
ythe yfollowing yare ythe ywindow ywidth yand ywindow ylevel yselected: yA)window ylevel
y=0, ywindow ywidth y=500 yB)window ylevel= y+300, ywindow ywidth= y500 yC)window
ylevel y=+100, ywindow ywidth y=1000 yD)none yof ythese y- ycorrect yanswers y-A)
ywindow ylevel y=0, ywindow ywidth y=500
What yis ythe yvolume yof ya yvoxel yif ya yslice ythickness yof y3 ymm, ya y512x512 ymatrix
y& ya yreconstruction yfield yof yview yof y25.6cm yare yused yA) y0.75mm³ yB)1.5mm³ yC)
y6.0mm³ yD)none yof ythese y- ycorrect yanswers y-A. ySolve ythis yby yfinding ythe ypixel
ysize yfirst yFOV/matrix ysize y... ythat yis y0.5 y... ynow ysquare ythat y0.25 y.... ymultiply
ythat yby yslice ythickness yand yyou yget y0.75
Which yof ythe yfollowing yparameters yis yresponsible yfor ypartial yvolume yaveraging: yA)
ymatrix ysize yB) ykVp yC)slice ythickness yD) ypatient ydose y- ycorrect yanswers y-C
Voxel yequation y- ycorrect yanswers y-pixel yarea yx ysection ythickness
What yis yinterpolation? y- ycorrect yanswers y-Mathematical ymethod yfor ytaking
ySPIRAL ydata yand yviewing yit yas yAXIAL yimages
Bone ywindows y- ycorrect yanswers y-2000-4000 yWW
200-400 yWL
Lung ywindows y- ycorrect yanswers y-1400-1600 yWW
(-)400-600 yWL
Modular yTransfer yFunction? y- ycorrect yanswers y-graphical yrepresentation yof
ySPATIAL yRESOLUTION ymeasured yin ylp/cm, ytells yhow ysmall yyou ycan yscan
ywithout yblurring
Decrease ypartial yvolume yaveraging? y- ycorrect yanswers y-Reduce yslice ythickness
Which yportion yof ythe ypancreas yis ythe ymost ycommon ysite yfor ytumors?; yand ywhere
ylocated? y- ycorrect yanswers y-The yhead yof ythe ypancreas. yIt yis ylocated
yapproximately yat yT12
LUNG yWINDOW
(-) yIS yAIR y- ycorrect yanswers y-2000 yWW yand y-200 yWL y=
