??????CT?????

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?9????????CT???? 2005.10.15
??????CT?????
???????????? ????????? ????
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CT???(??)????????,??
?? X????????????????????????(?????) ??
??????? CT??????? ?? ???????, 88(8),
759-771(1989) ?? X?CT????????????(?) ??
????????? X?CT????????? ?? ?????,47(1),56-63
(1991) ?? ???CT?????????????????????? ??
????????? ???CT????? ?? ?????,53(11),1714-1732
(1997)
American Association of Physicists in Medicine.
Report no. 1 Phantoms for performance evaluation
and quality assurance of CT scanners (1977)
3
CT???????
?????????? ????? ???????????
??????????(?????) ????????? ??????????
?????????? ??? ??? etc
???????,?????.....
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CT???????
?????????? ????? ??????????
???????????(MTF) ??? SD(????)???
?????????? ????????? ??????????
???????? ??? etc
?????,?????????????
5
??????????
?
?
200mm
??
µ?-µ??(0)
µ?0.195
CS
CT?? CT??
CT???????????????? ???,???CT?,?0,??-1000?????????
???????
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?????(?????)
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??????????
?????????????????
???
??????????????????
?? ????????????? ??CT?,????????????????
???????????? ?????,???????????
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?????????????????
??????
????CT??150 ??CT?-1000 CT??1150
?????? 0.3mm2mm
????????????? ????????????? ?????
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??????????????????
????????????????? ??????????????????
10
??????????????????????
11
??????
??????
?????????(1or2)????????????????, ?????????????????
????????
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???????,??????
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??????????????????
????????MTF??
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?????(?????)
????????? ??????PSF(point spread
function) ???,???? MTF(modulation transfer
function) ????????????
PSF
??????
????? 0.1mmf
??????
Z??
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????????(???)??
MTF????
0.5mm
1 cycles/mm
1mm
MTF??,0.5mm???????
1mm
0.5 cycles/mm
2mm
???????? ????????
MTF??,1mm???????
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????????????MTF??
????????? ???MTF????? ?????????
????? 0.1mmf
Z??
???????????????,???????????
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?????????????
??50mm??? ???????
?
??
0.1mmf????(0.10.2mm??????)
?????FOV50mm ??????????
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?????????MTF?? ???
??????,?????????ctpsf? http//www.owari.ne.jp/kit
ikawa/
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??,DICOM???????? ?????? DICOM??????
3??WS??(????????)
Dicom???Dicom2???? ?profile????? Direction?,MTF???
???? VAN???????OK ?????????????Preparation ?????
Dicom???Dicom2?????? ????????? ???????????
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MTF?????Lpos-set??????? ??????????????????? ??????
????????? MTF?????Rpos-set???????
???????????????? ????????????????? ???????????????
???,MTF?????Set-Base
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MTF?????Save to Clipbd?, ???????????????, Excel???
??????
MTF?????MTFcalc.?,??? FOV,????X??full
scale??? Save-MTF?,??? Compare-MTF?,????????
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?????????? FOV?50mm???????
-gt??????????????,????? ?????????????????.
?????????????,????? -gt??????????. ??????????
-gt 2030mm offset?? ???????????????.
-gt???????????????,??? ?????????????????. (??
???????,???????????????)
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MTF??????????????
0.5mm
0.5mm
0.5mm
1.0
1.0
1.0
0
1.0
0
1.0
0
1.0
?????????,MTF?10???????????
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??????????????
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MTF????????
?????????????? (???????????????(??)) ???,????
???? ?????,??????????
?????????????? ??????????? ?????,?????????? QQ
??????????????????????
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SOMATOM VZ?????
AB20
AB30
AB35
AB40
?????????????????? ???MTF??????????
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AB30
AB35
Q??????????????

1. 10???????,???????????????

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????????????
Center
90mm off-center
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?????????
??
??
??
??
??
??
??
??
??
????????????????????????
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???????????MTF???
1.0
0.8
0.75sec
0.6
Modulation transfer factor
0.4
0.5sec
0.2
0.0
0.0
0.2
0.4
0.6
0.8
1.0
1.2
Spatial frequency (cycles/mm)
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??????
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??????????
?????????????????
???
???????????????????????
?? ????????(??)???? ????????????
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?????????????????
?? 220mmf ????CT??10
Z??
CT??10????????????????????????
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??CT?? (?????5mm)
?????....
SD(CT??????) 710
???????CT?? 10??
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?????(????????)?????
CT??
5
10
20
2
3
5
7
?
SD3
SD5
SD8
SD10
???????????,5mm????????? CT??10?????????
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??????????????
200mA
300mA
500mA
SD8
SD4.5
SD6.5
???????
??????
23???????????????
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?????????????
???????????
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???????(?????????????)
????????????
??????
?????????
??????????
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Winer Spectrum ???
??????(???????)
200mmf??????
??
???256X256?? ????????
??????1cycles/mm????? ?0.5mm??????????????0.5mmX51
2256mm ??????FOV?256mm????????????
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?????????????
??????????????????
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CTWS????
Dicom???Dicom2?????? ????????? FOV?????? VAN??????
??????? Clip for excel?????????? ??????????????
????????,?????????? ???????????????? ????
???????????????? OK
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??????WS????
???
??
??????????????????????? ??????,???
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SD??????????
??ROI(region of interest) 15x15??????
??????(200mmf)
?????????
?????????????????,????? ??4???CT??????(????S.D.)?
?????
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?????(????????)???
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????????????????
????
??????
?????
????CT?????????????
Z??
?????? ????????
W
?????T TW/v3
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???????????????
?????????
5cm
??????
????(??????????????) ??0.1mm0.5mm ????????1/201/
10?????? 1/10?????5?????????
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????????????(??????)???????
??????????????SSP???? ?????(0.05mm???????)
(???????)
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????????? ?????
Z??
????? ??????????1/101/20 FOV3050mm
1.0
0.5
???
0.0
0
5
10
15
20
?????? (mm)
?????????ROI????? ROI???CT????
???????????CT??????????
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SSP????????SSPANA? (http//www.owari.ne.jp/kitika
wa)
??????????????????Z???????? ????CT????????????????
????? ????????SSPANA??????????Get-clip? ??????????
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?????????Correct?SSP???????? ?????????????????????
?????? ????????????Set-base?,?????????? ???
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??????????Move??????????OK??? Z-step for
clip?,????OK? FFT???????,Full freq.?,???????????
5mm??0.5??,1mm??,1.5???,?????
Color?,???????????,???????? ?????????Recon
int.???????
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????,??????????????????? BANDwi?,????(band
width)???????????? ????????,????????????
????????
SaveSSP?,????SSP? ??? LoadSSP?,?????? CompareSSP?,
??????? ??? SaveMTF?,?????MTF? ??? LoadMTF????????
??,????????????
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?????????????
???,?????????(????)
??????,?????????!
???????????,?????????????
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???????????????