X?CT??????????? ??????????????

1
X?CT?????????????????????????

• ?????????????? ?? ??
• ????????? ?? ??

2
??1

• ???????????????????????

?CT????????????????????100mm ?CT????????????????
????????????????TLD????????????????????????
3
??2

• X?CT????Beam-Shaping(bow-tie)Filter???????????????
  ???????X?????????????

4
??

• ????????????????????????EGS4?KEK???????????????LSC
  AT(Low-Energy Photon-Scattering Expansion for the
  EGS4 Code)??????????????????????????(???????TLD??
  Mg2SiO4?CaSO4)???????????????
• ???????????????1??????
• ????????????????TLD?????????????????????????????
• ?1Medical Physics July2002 Volume29,Number7

5
?????????????1

• ?????
• ????(??32cm)?JIS?????????
• ???????????PMMA
• JIS??????PMMA
• ??????1cm???0.4cm????
• ???-???????60cm
• ???
• ??????????(????10mm?????38?)???????

6
?????????????2
? PCUT?1keV?ECUT?512keV??? ? ?????????10??????????
???????????? ? FSD?????????1?????????109? ????
??????(????) IRAYL?INCOH?IPROF?IMPAC?IEDFL?IPHTE ?
????? EGS4(?????????) LSCAT?????
7
????????
??-????????60cm
6?
???(???) ??1cm0.4cm
????1cm?
????1cm?
32cm
Z?
??
??
????PMMA ???????
Y?
40cm
????Z???????????1, 5, 9, 13, 17cm?????
8
JIS??????????
??-????????60cm
????1cm?
????5cm?
20cm
??
X?
6?
Z???
Y?
40cm
30cm

????Z???????????1, 5, 9, 13, 17cm?????
9
??1
??
X?CT????????????????????Beam-Shaping(bow-tie)Filt
er?????????????????????Filter???(??)??????????????
????(???)
Filter
??????Filter?????????????? ????????
???
????????????(???????????) ?????????????????
10
??2
A?????????????X???5cm
B?????????????X??? 510cm, -5-10cm
C?????????????X??? 10?20.6cm,-10-?20.6cm?
A
B
C
B
C
A
X?
Y?
? ??-??????60cm?????38??????60tan(380.5p180)?
???????
?????10mm???
11
?????AEmax120keVEeff 52.5keV
?????BEmax120keVEeff 58.8keV
?????CEmax120keVEeff 74.3keV
????
?????(keV)
??????????
????????????TCT300???????????????? Birch??????????

12
?????????????(?????)
???????(keV)
??????Z??????
13
???????

• ?????????????????????????(??)?????
• ??X?????????(52.5keV)?????(N52.5)?????????????????
  ???(Np)???????
• (N52.5-Np) (Np)100
• ???????????????()

14
??(CaSO4)??????????()???
?????????????()
??????Z??????
15
??(Mg2SiO4)??????????()???
?????????????()
??????Z??????
16
????????????????()???
?????????????()
??????Z??????
17
JIS?????????? (??????????)
???????(keV)
??????Z??????
18
??(Mg2SiO4)??????????()JIS?????
?????????????()
??????Z??????
19
??(CaSO4)??????????() JIS?????
?????????????()
??????Z??????
20
????????????????() JIS?????
?????????????()
??????Z??????(cm)
21
??????

• TLD??(Mg2SiO4CaSO4)??????????????X???????????????
  ??????????(??Z???????)?10???????????????
• ????????????5???????????????

22
??1

• TLD???????10???????????????
• ????????????????????????????Z?????????????TLD?????
  ?????????????????????????????????X????????????????
  ??????????????????????????????????????????????????
  ?CT?????????????????????????????????????

23
??2

• ???????????????????????JIS???????????????????????5
  ???????????????
• ??????????????????????????????????????????????????
  ?????????????????????????????????

24
???????

• ???????1?????????????????????????????????????????(
  ???)?????????????????????????????
• ?????????????????????????????????????