ESTIMATION OF BREAST DOSE AND CANCER RISK IN CHEST AND ABDOMEN CT ...

68 Pages·2015·2.25 MB·English

S U D A N A C A D E M Y O F S C I E N C E S
ESTIMATION OF BREAST DOSE AND
CANCER RISK IN CHEST AND ABDOMEN
CT PROCEDURES
b y :
S u h a A b u b a k e r A li E lt a h ir
U n ite d A r a b E m ira te s U n iv e rs ity
2008
A t h e s is s u b m it t e d in p a r t ia l f u lf illm e n t f o r t h e r e q u ir e m e n t s
o f M a s t e r D e g r e e in M e d ic a l P h y s ic s
S u p e rv is o r:
D r.A b d e lm o n e im A d a m M o h a m e d S u lie m a n
M a y 2013
ESTIMATION OF BREAST DOSE AND
CANCER RISK IN CHEST AND ABDOMEN
CT PROCEDURES
b y :
S u h a A b u b a k e r A li E lt a h ir
A t o m ic E n e r g y C o u n c il
E x a m in a t io n c o m m it t e e
N a m e T itle S ig n a t u r e
Prof. Faroug Id res Habbani External Examiner
C g Y T ~ .
Dr. Abdelmoneim Adam Mohamed Sulieman Supervisor
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j / ; JYH£
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Mr. Ammar Mohamed Alamin Academic
Representatives Affairs
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D e d ic a tio n
This thesis is dedicated to my father, w ho taught me that the best kind o f know ledge
to have is that w hich is learned for its own sake.
It is also dedicated to my mother, w ho taught m e that even the largest task can be
accomplished i f it is done one step at a time.
I
A c k n o w le d g e m e n ts
It is a great pleasure to acknow ledge all those people w ho have given me tremendous
help and support in com pleting this study especially to my supervisor, Dr.
Abdelmoneim Adam Mohamed Sulieman for his guidance and assistance throughout
the whole period o f this study.
I also would like to thank all Heads and sta ff o f Departments o f D iagnostic Imaging
in hospitals that w ere involved in this study for their perm issions and assistance
during the sam pling o f the data.
Lastly, I w ould like to thank my fam ily for their consistent support.
ii
C o n te n ts
1 No. Item Page No.
Dedication 1
A ft
A cknow ledgem ents 11
ft
0 ft
Contents 111
List o f tables
VI
0 0
List o f figures
Vll
Abbreviations ix
Abstract
X
Abstract [Arabic] xi
C h a p t e r O n e : I n t r o d u c t io n
LI Introduction to computed tomography (CT) Imaging i
\ 2 Radiation dose in CT examination 2
Radiation Risk during CT Chest and Abdomen 3
1 3
1.3.1 CT Chest 3
1.3.2 CT Abdomen 4
\ A Problem o f study 4
O bjective 5
1 .5
T hesis outline 5
1 .6
III
I I C h a p t e r T w o : T h e o r e t ic a l B a c k g r o u n d
1 CT machine (com ponents) 6
I2 '1
2.1.1 CT Gantry 6
2.1.2 X-ray Tube, Collim ation, Filtration 7
9
2.1.3 | Detectors
2.1.4 1 Data A cquisition System (D A S) 10
2.1.5 CT Patient Table or Couch 11
2.1.6 Power Distribution Unit 11
2.2 CT Imaging Technique 11
2.2.1 Chest CT scan 13
2.2.2 Abdomen CT scan 14
2.3 1 Radiation Quantities and Units 15
2.3.1 Radiation Quantities 15
2.3.2 Radiation Units 16
16
2.3.3 1 Exposure
2.3.4 Absorbed D ose 17
2.3.5 1 D o se Equivalent 17
2.3.6 E ffective D ose 18
2.3.7 Computed Tomography D o se Index 19
2.3.8 Computed Tomography D o se Length Product 20
2.3.9 Computed Tomography D ose Index Volum e 20
2.4 [ Breast Radio-sensitivity 21
2.5 Previous studies 26
IV
C h a p t e r T h r e e : M a t e r ia ls a n d M e t h o d s
3.1 32
In tro d u ctio n
32
3 2
P a tie n t d a ta
33
3 3 C T m a c h in e s
14 33
D a ta c o lle c t io n
15 34
C T d o s e m e a s u r e m e n ts
16 34
O rg a n d o s e d e te r m in a tio n s
17 34
C a lc u la tio n o f e f f e c t iv e d o s e
18 36
C a n c e r r isk e stim a tio n
36
1 9
A n a ly s is o f d ata
C h a p t e r F o u r : R e s u lt s a n d D is c u s s io n
4.1 37
R e s u lts
43
4 2
D is c u s s io n
C h a p t e r F iv e : C o n c lu s io n a n d R e c o m m e n d a t io n s
5.1 48
C o n c lu s io n
48
5 2
R e c o m m e n d a tio n s
49
R E F E R E N C E S
53
A P P E N D IX A
A P P E N D IX B
54
L ist o f ta b les
1 Table Item P ag e No.
The evolution o f typical values for high-performance CT
13
machines.
1 1
W eighting Factors as defined in ICRP 2 6 ,6 0 and 103. 25
2 .2
Patient population o f the study classified per hospital and type o f
32
3 .1
examination.
1 3.2 1 CT machines. 33
| ^ 1 Current Conversion Factors for Obtaining E ffective D o se From
3
35
the D ose-Length Product.
I Patient demographic data and exposure parameters during CT
4.1 exam used by each hospital: Mean ± sd deviation and the range in 38
the parenthesis at constant kVp =120.
I DLP and CTDIvoi for patient during CT exam used by each
4.2 hospital: M ea n isd deviation and the range in the parenthesis at 39
constant kVp =120.
1 DLP and E ffective dose for patient during CT exam used by each
hospital: M ean±sd deviation and the range in the parenthesis at
39
constant kVp =120.
I 1 E ffective dose and breast dose for patient during CT exam used
, by each hospital: M ean±sd deviation and the range in the
4 4 I 40
parenthesis at constant kVp =120.
Mean organ radiation equivalent dose (m Sv), risk coefficients and
radiation risk per procedure.
45
4.6 I Comparison o f patient dose during CT with previous studies. 46
VI
L is t o f fig u res
Figure Item 1 P age N o.
2.1 6
CT scanner.
2.2 CT Gantry. 7
2.3
Image acquisitions in CT.
8
Scintillation detector im age acquisition in CT.
2.4 9
2.5 1°
X enon Gas detectors.
The scanning techniques used in the first four generations o f CT
2.7
scanners.
1 2
2.8 Radiation quantities.
1 6
2.9 Absorbed dose.
1 7
2.10 Computed Tomography D ose Index.
1 9
2.11 D o se Length Product. 20
Breast shielding during CT procedures for adults (A ) And
2.12 1 22
pediatric ( B ) .
Distribution o f the scanner technology and CT manufacturers o f
3.1 33
the im aging departments participating in this study.
Screensaver show s exam ple o f radiation report generated by
3.2 m odem M DCT and sent to PACS as separate series. Total dose-
3 5
length product is displayed in mGy.cm.
( a r r o w )
4.1 CTDIV0] in the hospitals during the chest and abdomen scans.
4 1
4.2 DLP in the hospitals during the chest and abdomen scans.
4 1
Correlation between DLP (m Gy.cm ) and E ffective dose (m Sv) to
4.3
fem ale patient undergoing CT chest exam in the three hospitals.
4 1
VII