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Microsoft Word - WG Report Imaging Dose _final0324rev.doc
1
2016
NTT
1 2 kV Imaging Dose 3 2D 4 3D CTDI 5 3D I’mRT 6. D GB
image guided radiation therapy - quality assurance (IGRT-QA) 2012 4 IGRT-QA/QC WG report
1 IGRT cone beam computed tomography (CBCT) Imaging dose
2)
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achievable ALARA .
. X ±
± )
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gs
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± Al ±
w g
± 4) ± (20 50 keV ) CBCT 55 keV .
Fig. 1 ;:- (3 ml) Fig. 2 `;:- ]6 ml),> `!
g
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.
Al 2.699 g/cm3
Al Table 2 2D Bowtie filter
O
AAPM TG-61 AAPM protocol for 40 - 300 kV x-ray beam dosimetry in radiotherapy and radiobiology 6 Al ±
Table 3





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) Al
)
40 cm 1.40 1.55 Fig.4 BSF
) . g
100 cm SSD 85 cm
2 . BSF SSD 80cm
.Table 4 Varian OBI ±
First HVL mm AL
Anatomy kV
Head-AP 100 Head-Lat 70 Thorax-AP 75 Thorax-Lat 95 Abdomen-AP 80 Abdomen-Lat 85 Pelvis-AP 75 Pelvis-Lat 105
mAs

0
5
10
15
20
msec
Varian 2 Elekta 1 3 2D X ACCU-GOLD+ Radcalc AGMS-D+
Fig. 2 ±
. 80,100,120,125 kV Elekta XVI 120 kV 80 mA Varian OBI 40 mA Elekta XVI 10,20,32,80,250 msec Varian OBI 10,20,32,40 msec Elekta XVI . Bowtie Filter ) Gy/msec
100 kV 120 kV Fig. 5 Varian OBI Fig. 6 Elekta XVI Varian OBI .
Varian OBI 1 X
) Fig. 7 80 msec
) - R B I B 3 6 '
Varian OBI , X 85 cm Table 5
) 100 cm 100 cm 3.2% .
Varian OBI )
msec
0
5
10
15
20
msec
OBI Ver 1.6 80 mA 80 mSec (mGy)

100cm 100 cm 85 cm

IGRT
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CTDI IBA I’mRT CTDI 2D 4
gs
ge
± 16 cm ,32 cm ± 10 cm Fig. 8,9 c 1 cm 4 p CTDI100
weighted CTDI(CTDIw) Fig. 10 IGRT ±
Volume CTDI (CTDIvol)
× Varian OBI 2 cm
Fig. 9 CT Chamber PTW 30009`radius 3.5 mm_length 100 mm Fig. 8 CTDI Acryl phantom =7( 16 cmφ×15 cm
11
) Bowtie filter ± Head Full Fan Bowtie filter Pelvis Half Fan Bowtie filter
CTDI Table 6
O
CBCT Bowtie filter 2D Table 7 Varian OBI 80 120 kV Al 5 6 mmAl ± 42 46 keV Elekta XVI
6 8 mmAl 46 55 keV )
N T
CTDI100,c
CTDI100,
Fig. 11 CTDIw (16 cm) Fig. 12 CTDIw (32 cm)
0
10
20
30
40
C TD
Iw (m
G y)
C TD
Iw (m
G y)
V T B I
Varian Customer Technical Bulletin12 Varian OBI CTDIw 3 Table 9 10% ) Standard Dose Head
Pelvis Fig. 13
CTDIvol = CTDIw / Pitch Pitch = 1 CTDIw
CTDIvol DRLs2015 )
CBCT ± )
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Fig. 13> Varian OBIDCTDIw39"5
0
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20
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!! = !!!!"# !! !"!"#$%# ,!! ! ! !!" ! !"#$% ,!"# Dw (Gy) Mphant (nC) N0 (C/kg/nC) CFFarmer,N0 W / e W (J/C) (en /)water,air ±
g
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type 30013 PTW 3 ml DC300 Scanditronix Wellhofer Table 10 0.2 )
Fig. 14 I’mRT
± Table 11 Varian OBI 6 Elekta XVI 2 Fig. 15
Couch Varian Couch 6 Brainlab Couch
Varian OBI,Elekta XVI Elekta XVI ) Elekta XVI ) Varian OBI Standard Dose Head
0.7% 2SD Pelvis 3.4% 2SD ) Varian Couch Brainlab Couch Brainlab Couch 10%
Fig. 16
kV 100 125 100 120 mA 20 80 20 40
msec 20 13 20 40 projections 360 655 183 660
Exposure(mAs) 145 680 73 528 Filter Full Half F0 F1
Scan mode Full Half - -
0
1
2
3
4
5
6
7
8
0 1 2 3 4 5 6 7 8 9 10
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0
5
10
15
20
25
30
35
40
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0
1
2
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4
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XVI
0 5 10 15 20 25 30 35 40 45 50
0 1 2 3 4 5 6 7 8 9 10
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Table 13 Varian OBI ±
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Table 12 W[QMYZ$CFHkQ,kphant Table 13 2,. D"5 Standard Dose Head Pelvis 100kV 20mA 20msec 120kV 80mA 13msec
µ enρ 4.33 mGy 28.41 mGy
ND,WQ 4.19 mGy 28.03 mGy
difference -3.23 % -1.34 %
) IGRT IGRT ) DRLs
1 IGRT-QA/QC Working group report,2012 2 QA/QC . ( :IGRT
). 2010; 30: 49-53. 3 Palm A, Nilsson E and Herrnsdorf Lars Herrnsdorf , Absorbed dose and dose rate using the Varian OBI 1.3
and 1.4 CBCT system. Journal of Applied Clinical Medical Physics, 11, 229-40,2010 4 , (25) ,2006 5 http://physics.nist.gov/PhysRefData/XrayMassCoef/ElemTab/z13.html 2017 3 25 6 C.M. Ma, C. W. Coffey, L. A. DeWerd, C. Liu, R. Nath, S. M. Seltzer, J. P. Seuntjens, “AAPM protocol for
40-300 kV x-ray beam dosimetry in radiotherapy and radiobiology”, Med. Phys. 28, 868-893 ,2001. 7 Grosswendt, B., Dependence of the photon backscatter factor for water on source-to-phantom distance and
irradiation field size. Phys. Med. Biol. 35, 1233-1245,1990 8 Klevenhagen, S.C., Experimentally determined backscatter factors for X-rays generated at voltages between
16 and 140 kV. Phys. Med. Biol. 34, 1871-1882.,1989. 9 , X 57(12),1503-1510,2001 10 (J-RIME)/ ± ,2015.6.7 11 Varian medical systems, Dose in CBCT – OBI Advanced Imaging. On-Board Imager® (OBI) kV imaging
system v1.4 and v1.5. Revision 1.3. Jun , 2012. 12 Varian Customer Technical Bulletin OB-885 Rev A 13 , (33)
,2015

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