Mastering Digital Radiography and Radiation Protection WCEC 2015

2/8/2015
Mastering Digital
Radiography and
Radiation Protection
72” SID 85 kV @ 3.2 mAs
21.8 MicroR’s
WCEC 2015
Dennis Bowman RT(R)
Staff Radiographer
Community Hospital of the Monterey Peninsula (CHOMP)
Speaker/Consultant – Digital Radiography Solutions (dRs & MTMI)
72” SID 115 kV @ 4 mAs
50.9 MicroR’s
Barry Burns –the CR guru
� Barry Burns ­ MS, RT(R), DABR – Retired
adjunct Professor of Radiologic Science,
University of North Carolina School of
Medicine in Chapel Hill, North Carolina,
stipulated that when using CR everyone
can increase 1515-20 kV from film/screen
techniques (except Konica which is 5­
5­10 kV).
40” SID 85 kV @ 16 mAs
244.6 MicroR’s
The following slides show a hand phantom
exposed from 50 to 100 kV to demonstrate
the minute differences visualized on an image
using higher kV and lower mAs with both CR
and DR.
1
2/8/2015
CR
50 kV
CR
60 kV
CR
70 kV
CR
80 kV
CR
90 kV
CR
100 kV
2
2/8/2015
DR
50 kV
DR
60 kV
DR
70 kV
DR
80 kV
DR
90 kV
DR
100 kV
3
2/8/2015
These are the digital Optimum kVs
as developed by Barry Burns
DIGITAL OPTIMUM kV
Universal CR Technique Chart
100% More mAs
UNIVERSAL CR TECHNIQUE CHART
Body Part - Adult
Chest (Bucky/Grid)
Chest (Non-Grid)
Abdomen
Extremities (Non-Grid)
Extremities (Grid)
Extremities (Bucky)
AP Spines
C-Spine Lateral
T-Spine Lateral
L-Spine Lateral
Ribs
Skull
BE (Air Con)
Abdomen (Iodine)
Pediatric:
Infant Extremities
Pediatric Chest (Screen)
kV
110-130
80-90 (105)
80-85
65-75
75-90
85-95
85-95
85-100
85-100
85-100
80-90
80-90
110-120
76-80
50-60
70-80
Size of the Patient – The techniques
are of a small, medium and large male
Part
View
Small
kV
AP (Grid)
85
13.5
85
27
85
54
Ankle
Ankle
Ankle
AP
Obl
Lat
70
70
70
2.6
2.4
2.2
70
70
70
2.8
2.6
2.4
70
70
70
3.2
3
2.8
Chest -Adult
Chest -Adult
Chest (2-9 lb)
AP (non grid - 72")
AP (non grid - 72")
AP (Non Grid - 40")
90
80
75
3.2
4
1.8
90
80
75
4.4
5
2.4
90
80
75
7
6.4
3
Chest (2-9 lb)
Chest (10-20 lb)
Chest (10-20 lb)
Lat (Non Grid - 40")
PA (Non Grid - 72")
Lat (Non Grid - 72")
77
80
82
2.4
2
2
77
80
82
3
1.8
2.4
77
80
82
3.6
2.2
2.8
Chest (25-35 lb)
Chest (25-35 lb)
C-Spine
PA (Non Grid - 72")
Lat (Non Grid - 72")
AP (grid - 40")
82
85
85
2
2.8
5
82
85
85
2.4
3
6.4
82
85
85
2.8
3.2
8
C-Spine
C-Spine
C-Spine
AP (non grid - 40")
Odontoid (grid - 40")
Lat (grid - 72")
70
85
85
4.8
6.4
14
70
85
85
6
8
18
70
85
85
7.2
9.6
22
C-Spine
Lat (non grid - 72")
70
12
70
16
70
20
C-Spine
Elbow
Elbow
Finger
Foot
Foot
Foot
mAs
kV
Swimmers (grid - 40") 96
AP
Oblique/Lateral
All Views
AP
Obl
Lat
Forearm
Forearm
Hand
AP
Lat
PA
Hand
Hand
Obl
Lat
mAs
50
96
70
96
100
70
70
66
70
70
70
2.2
2.4
1.2
2.4
2.6
3.6
70
70
66
70
70
70
2.6
2.8
1.6
2.8
3
4
70
70
66
70
70
70
3
3.2
2
3.2
3.4
4.6
70
70
66
1.8
2.2
1.4
70
70
66
2.2
2.6
1.8
70
70
66
2.6
3
2.2
66
70
1.8
2
66
70
2.2
2.4
66
70
2.6
3
Universal CR Technique Chart
100% More mAs (Page 2)
UNIVERSAL CR T ECHNIQUE CHART
What does mAs do in the digital world?
Large
mAs
Abdomen-(Most mAs)
Part
120­160 lbs.
� Small = 120­
� Medium = 160­
160­200 lbs.
� Large = 200­
200­240 lbs.
� Females would be approximately 10 lbs. lighter.
100% More mAs
Medium
kV
View
Hip
A P (grid )
Hip
AP ( non grid )
Hip
X-Table Lat (grid)
Humerus
AP ( non grid )
K nee
A P/Lat (grid)
K nee
A P/Lat (non grid)
K nee
Sunrise (non grid)
L-Spine
AP
L-Spine
X-Table Lat (grid)
Mandible
Obl (grid - 40")
Mandible Obl (non grid - 40")
Pelvis
A P (grid)
Ribs
Upper (72")
Ribs
Lower (40")
Ribs
Obl (72")
S houlder
A P (grid)
S houlder
A P (non grid)
S houlder
Y V iew (grid)
S houlder A xillary (non grid)
S inus
Caldwell
S inus
Waters
S inus
Lateral
Skull
PA
Skull
Lat (grid)
Tib-Fib
A P (non grid)
Tib-Fib
Lat (non grid)
Toe
A ll Views
T-Spine
AP
T-Spine
Lat (2 sec)
Wrist
PA
Wrist
Obl
Wrist
Lat
Small
100% M or e mAs
Medium
Large
kV
mAs
kV
mAs
kV
mAs
85
75
90
70
85
70
70
85
96
81
70
85
80
85
80
85
70
85
70
85
85
85
85
85
70
70
66
85
90
66
66
70
14
6
48
3.6
7.6
6.6
8.4
28
70
14
6
20
18
32
28
10
4
18
6
11
13
5.6
14
7
4.8
4.4
2
18
44
2
2.4
3.2
85
75
90
70
85
70
70
85
96
81
70
85
80
85
80
85
70
85
70
85
85
85
85
85
70
70
66
85
90
66
66
70
18
8
72
4.4
9
8
10
36
90
20
8
30
24
42
36
15
5
26
8
14
16
7
17
8
5.6
5.2
1.8
24
60
2.4
2.8
3.6
85
75
90
70
85
70
70
85
96
81
70
85
80
85
80
85
70
85
70
85
85
85
85
85
70
70
66
85
90
66
66
70
24
10
120
5.2
10.8
9.6
12
50
130
24
10
40
32
56
48
20
6.4
36
10
17
19
9
20
10
6.4
6
2.2
32
80
3.2
3.6
4.8
Exposure Index numbers
� Not what it did in the film world.
� To a large extent, mAs does not really control
� Dose Exposure, Exposure Index/Indicator numbers.
brightness (density) any more.
� Brightness is almost completely controlled by
processing algorithms.
� You just need enough mAs or your image will
have quantum noise (mottle).
(S, LgM, EI, EI_s, ReX,
ReX, EXI, DEI) are how you tell if
your technique was correct.
� The Exposure Index ­ EI (what we will call it from
now on) number is best if the centering and
collimation are very good.
4
2/8/2015
EI ranges
Critiquing digital images
1.7­2.3 LgM range, Fuji’s
� The concept of Agfa’s CR 1.7­
� The EI numbers are the number 1 way to critique
CR 400­
400­100 S range, GE’s (DR) .2­
.2­.6 range and
Siemens‘ DR 200­
200­900 range.
� Even with the range you should always be
shooting for the “best” number in that range
(which means the lowest dose).
Critiquing digital images (continued)
� It is impossible to prove you used the
correct technique if all you are using is what
the finished image looks like as your gauge.
� Witness the awesome power of
Automatic Rescaling
your image.
� You should definitely use the magnification mode
to check for noise and burn.
� You should always be able to Level and Window
and make your image look well penetrated and
contrasty.
contrasty.
In the film world this
is how much darker
(or in other words
how much more
radiation the patient
is getting) when you
increased the mAs.
50% Darker
Fuji
85 kV @ 4 mAs ­ S# 357
100% Darker
200% Darker
85 kV @ 8 mAs ­ S# 171
5
2/8/2015
85 kV @ 32 mAs ­ S# 38
85 kV @ 200 mAs ­ S# 6
85 kV @ 400 mAs ­ S# 3
Carestream Portable Detector
85 kV @ 2 mAs
EI 1385
85 kV @ 4 mAs
EI 1682
85 kV @ 8 mAs
EI 1966
6
2/8/2015
85 kV @ 16 mAs
EI 2257
85 kV @ 45 mAs
EI 2405
85 kV @ 32 mAs
EI 2517
What are the technique
differences between CR and DR?
� For all CR (except Agfa) you can use at least 50
times too much mAs and have a perfectly
diagnostic/passable image.
� For most DR you can use about 10 times too
much mAs.
How can there be a
Universal CR/DR technique chart?
Universal CR Technique Chart
Least mAs
UNIVERSAL CR TECHNIQUE CHART
Part
� As we all well know, this would have been
impossible in the film/screen processor days.
� All modern generators (25 years or newer) are
high frequency and all tubes are the same on the
inside.
� All CR/DR manufacturers set their systems up to
have the perfect EI# appear when 1 mR hits the
Image Receptor.
View
Small
kV
mAs
Least mAs
Medium
kV
Large
mAs
kV
mAs
Abdomen-(Most mAs)
AP (grid)
85
13.5
85
27
85
54
Ankle
AP
70
1.3
70
1.4
70
1.6
Ankle
Obl
70
1.2
70
1.3
70
1.5
Ankle
Lat
70
1.1
70
1.2
70
1.4
90
2.5
90
3.2
90
Chest -Adult
AP (non gri d - 72")
80
2
80
2.5
80
3.2
Chest (2-9 lb)
AP (non gri d - 40")
75
0.9
75
1.2
75
1.5
Chest (2-9 lb)
Chest -Adult
Lat (non gri d - 40")
AP (grid - 72")
77
1.2
77
1.5
77
1.8
4
Chest (10-20 lb)
PA (non gri d - 72")
Chest (10-20 lb)
80
0.8
80
0.9
80
1.1
Lat (non grid - 72")
82
1.0
82
1.2
82
1.4
Chest (25-35 lb)
PA (non gri d - 72")
82
1.0
82
1.2
82
Chest (25-35 lb)
Lat (non grid - 72")
85
1.4
85
1.5
85
C-Spine
AP (grid - 40")
85
2.5
85
3.2
85
4
C-Spine
AP (non gri d - 40")
70
2.4
70
3
70
3.6
C-Spine
Odontoid (grid - 40")
85
3.2
85
4
85
4.8
9
85
C-Spine
Lat (grid - 72")
85
7
85
8
70
Swimmers (grid - 40")
95
25
95
35
95
50
Elbow
AP
70
1.1
70
1.3
70
1.5
Elbow
Oblique/Lateral
70
1.2
70
1.4
70
1.6
Finger
All Views
66
0.6
66
0.8
66
1
Foot
AP
70
1.2
70
1.4
70
1.6
Foot
Obl
70
1.3
70
1.5
70
1.7
Foot
Lat
70
1.8
70
2
70
2.3
0.9
10
70
1.1
70
1.3
Lat
70
1.1
70
1.3
70
1.5
Hand
PA
66
0.7
66
0.9
66
Hand
Obl
66
0.9
66
1.1
66
1.3
Hand
Lat
70
1
70
1.2
70
1.5
Forearm
70
70
11
Lat (non gri d - 72")
C-Spine
AP
6
1.6
C-Spine
Forearm
70
1.4
1.1
7
2/8/2015
Universal CR Technique Chart
Least mAs (Page 2)
UNIVERSAL CR TECHNIQUE CHART
Part
View
Small
Least mAs
Medium
mAs
kV
mAs
kV
mAs
AP (grid )
85
7
85
9
85
Hip
AP ( non grid )
75
3
75
4
75
Hip
X-Table Lat (grid)
90
24
90
36
90
60
Humerus
AP ( non grid )
70
1.8
70
2.2
70
2.6
12
5
AP/Lat (gri d)
85
3.8
85
4.5
85
5.4
Knee
AP/La t (non gri d)
70
3.3
70
4
70
4.8
Knee
Sunrise (non grid)
70
4.2
70
5
70
6
AP
X-Table Lat (grid)
L-Spi ne
85
14
85
18
85
25
96
35
96
45
96
65
Mandible
Obl (grid - 40")
81
7
81
10
81
12
Mandible
Obl (non grid - 40")
70
3
70
4
70
Pelvis
AP (grid)
85
10
85
15
85
20
Ribs
Upper (72")
80
9
80
12
80
16
Ribs
Lower (40")
85
16
85
21
85
28
80
L-Spi ne
Ribs
80
14
80
18
Shoulder
AP (grid)
85
5.2
85
7.5
85
10
Shoulder
AP (non grid)
70
2
70
2.5
70
3.2
Y View (g ri d)
85
9
85
13
85
18
Shoulder
Axillary (non grid)
70
3
70
4
70
5
Sinus
Caldwell
85
5.5
85
7
85
8.5
Sinus
Waters
85
6.5
85
8
85
9.5
Sinus
L ateral
85
2.8
85
3.5
85
4.5
PA
85
7
85
Skull
Lat (grid)
85
Tib-Fib
AP (non grid)
70
Tib-Fib
Lat (non grid)
70
2.2
Toe
All Views
66
0.7 5
T-Spi ne
T-Spi ne
3.5
2.4
8.5
24
85
10
85
4
70
2.8
70
2.6
70
3
66
0.9
66
1.1
9
85
22
90
12
85
5
70
85
all the charts (least dose to patient, most chance of mottle).
� The 33% More mAs chart uses 33% more mAs/dose than the Least mAs chart. � The 66% More mAs chart uses 66% more mAs/dose than the Least mAs chart. � The 100% More mAs chart uses 100% (double) more mAs/dose than the Least mAs chart. 5
Shoulder
Skull
Obl (72")
� The Least mAs chart uses the smallest mAs of Large
kV
Hip
Knee
Differences of the Least mAs to 100% More mAs technique charts
3.2
AP
85
Lat (2 sec)
90
30
90
40
Wri st
PA
66
1
66
1.2
66
1.6
Wri st
Obl
66
1.2
66
1.4
66
1.8
16
How to use these four charts
with the “Most mAs” because this has mAs” because this has � Begin with the “Most
the least chance of noise.
� In mid 2013 Bruce Long, First Author of � If you have a diagnostic image and the EI numbers show you can use less mAs, go to the “66% More mAs” chart.
� If again you have a diagnostic image and the EI numbers show you can use less mAs, go to the “33% More mAs” chart.
� Finally, if you have a diagnostic image and the EI numbers show you can still drop the mAs, go to the “Least mAs” chart.
Here is how much dose you save your patient when you increase the kV and decrease the mAs.
40"
40"
40"
40"
40"
70
81
85
90
96
20
10
8
6.3
4
221.0
152.8
134.8
120.0
87.0
30.90%
39.00%
45.70%
60.60%
5.0
4.0
3.2
2.0
Merrill’s, hired me to create the first ever digital technique charts for the Merrill’s Atlas.
� In it’s 50+ year history they have always had film/screen techniques.
� In the 14th edition which will be released in 2015, there will be almost 250 digital techniques included (half CR and half DR).
� Each technique will also have the ESE Dose.
PinnacaleHealth in Harrisburg, PA proves these numbers
� After giving a presentation for them, their Radiation Dose Saved
Radiation 50% EI
Dose
SID kV mAs
Saved Decrease
(mR)
(mAs)
(%)
Merrill’s Atlas of Radiographic Positioning and Procedures
50% EI
Dose
(mR)
Total Dose
Reduction
(%)
76.4
67.4
60.0
43.5
65.43%
69.50%
72.85%
80.32%
medical physicist wanted to prove my dose savings were accurate.
� After months of collecting data in specific rooms they used 260 procedures for AP and lateral lumbar spines and extremity’s. � He discovered that the average dose saved was 30.3% while my chart averages 30.9%.
8
2/8/2015
How Low Can You Go?
� This is my version of ALARA.
� With the new optimum kV’s already in place, it’s figuring out how low can we take the mAs and get an image with no, or acceptable/diagnostic mottle.
� I’m hoping that everyone will make it a competition or goal to see what is the minimum dose needed for any given projection.
� It takes no
It takes no skill to use too much mAs.
Universal Cesium DR Technique Chart
Least mAs
Least mAs
CESIUM DR UNIVERSAL TECHNIQUE CHART
Part
Abdomen
Ankle
Ankle
Ankle
Chest -Adult
Chest -Adult
Chest (2-9 lb)
Chest (2-9 lb)
View
Small
mAs
kV
mAs
AP (grid)
85
AP
70
Obl
70
Lat
70
AP (grid)
120
AP (non grid)
105
AP (non grid - 45") 75
Lat (non grid - 45") 77
4.5
1
0.9
0.8
1.2
1.1
0.5
0.65
85
70
70
70
117
105
75
77
9
1.1
1
0.9
1.8
1.6
0.65
0.75
85
70
70
70
117
105
75
77
18
1.2
1.1
1
2.4
2
0.8
0.9
80
82
82
85
85
70
85
85
70
95
70
70
66
70
70
0.6
0.8
0.7
0.9
1.7
1.5
2.1
4.5
4
17.0
0.8
0.9
0.4
0.8
0.9
80
82
82
85
85
70
85
85
70
95
70
70
66
70
70
0.75
0.9
0.8
1.0
2.4
2
2.7
6
5.2
25.0
0.9
1.0
0.5
1.0
1.1
80
82
82
85
85
70
85
85
70
95
70
70
66
70
70
0.9
1
0.9
1.1
3
2.6
3.1
7.5
6.8
35
1
1.1
0.6
1.2
1.3
70
70
70
66
66
70
1.2
0.6
0.7
0.5
0.6
0.75
70
70
70
66
66
70
1.4
0.8
0.9
0.6
0.75
0.85
70
70
70
66
66
70
1.6
1
1.1
0.75
0.85
1
Lat
AP
Lat
PA
Obl
Lat
detectors: (Cesium Bromide) and CsI
CsI (Cesium Iodide) � CsBr (Cesium Bromide) and Needle Phosphor detectors are high efficiency compared to standard Gadolinium based detectors . Gadolinium detectors need 33% ­­
detectors . Gadolinium detectors need 33% 100% more
100% more exposure than Cesium to produce a similar image.
� The newest generation of Cesium detector is now at 800 speed (previous best was 600 speed).
CESIUM DR UNIVERSAL TECHNIQUE CHART Least mAs
Large
kV
� Here are the differences in the Here are the differences in the quality
quality of DR Universal Cesium DR Technique Chart
Least mAs
Least mAs (page 2)
Least mAs
mAs
Chest (10-20 lb) PA (non grid - 72")
Chest (10-20 lb) Lat (non grid - 72")
Chest (25-35 lb) PA (non grid - 72")
Chest (25-35 lb) Lat (non grid - 72")
C-Spine
AP (grid - 40")
C-Spine
AP (non grid - 40")
C-Spine
Odontoid (grid - 40")
C-Spine
Lat (grid - 72")
C-Spine
Lat (non grid - 72")
Swimmers (grid - 40")
C-Spine
Elbow
AP
Elbow
Oblique/Lateral
Finger
All Views
Foot
AP
Foot
Obl
Foot
Forearm
Forearm
Hand
Hand
Hand
Medium
kV
Speaking of How Low We Can Go, let’s discuss DR detectors
Part
View
kV
mAs
kV
mAs
kV
Hip
Hip
AP (gri d )
AP ( non grid )
85
75
Small
4.5
2
85
75
Medium
6
2.8
85
75
Large
8
3.2
Hip
Humerus
X-Table Lat (gri d)
AP ( non grid )
90
70
16
1.2
90
70
25
1.5
90
70
40
1.8
3.6
3.2
mAs
Knee
Knee
AP/Lat (grid)
AP/Lat (non grid)
85
70
2.5
2.2
85
70
3
2.8
85
70
Knee
Sunri se (non grid)
70
2.8
70
3.4
70
L-Spine
L-Spine
AP
X-Table Lat (grid)
85
95
9
22
85
95
12
30
85
95
16
42
Mandible
Mandible
Obl (grid - 40")
Obl (non grid - 40")
81
70
4.8
2
81
70
6.4
2.8
81
70
8
3.4
Pelvis
Ribs
AP (grid)
Upper (72")
85
80
7
6
85
80
10
8
85
80
14
10
Ribs
Ribs
Lower (40")
Obl (72")
85
80
10
9
85
80
14
12
85
80
18
16
Shoulder
Shoulder
AP (grid)
AP (non grid)
85
70
3.5
1.4
85
70
5
1.8
85
70
6.5
2.2
Shoulder
Shoulder
Y View (grid)
Axillary (non grid)
85
70
6
2
85
70
9
2.5
85
70
12
3.2
Sinus
Sinus
Caldwell
Waters
85
85
3.7
4.4
85
85
4.7
5.4
85
85
5.7
6.4
Sinus
Skull
Lateral
PA
85
85
1.9
4.7
85
85
2.4
5.7
85
85
3
6.7
Skull
Tib-Fib
Lat (grid)
AP (non grid)
85
70
2.4
1.6
85
70
2.8
1.9
85
70
3.4
2.1
Tib-Fib
Toe
Lat (non grid)
All Views
70
66
1.5
0.5
70
66
1.8
0.6
70
66
2
0.7
4
T-Spine
AP
85
6
85
8
85
11
T-Spine
Wrist
Lat (2 sec)
PA
90
66
15
0.65
90
66
20
0.8
90
66
26
1.1
Wrist
Wrist
Obl
Lat
66
70
0.8
1.1
66
70
1
1.2
66
70
1.2
1.6
How similar CR is to DR (in mAs)
Digital
Radiography
Solutions
� DR (Ces
DR (Ces – 800 speed) = 7.5 mAs
� DR (Ces
DR (Ces – 600 speed) = 10 mAs
� DR (Gad) = 15 mAs
� CR = 25 mAs (66% More mAs chart)
Maximizing Image Quality, Minimizing Patient Dose
Dennis Bowman
Difference Between All Technique Charts (in mAs)
DR
Cesium
Least
mAs
10 mAs
DR
Cesium
33%
More
DR
DR
Cesium Cesium
CR
66%
100%
DR
Least
More
More Gadolinium mAs
13.3 mAs 16.6 mAs 20 mAs
15 mAs
CR
33%
More
CR
66%
More
CR
100%
More
Website: digitalradiographysolutions.com
Email: [email protected]
Phone: 831­601­9860
15 mAs 20 mAs 25 mAs 30 mAs
9
2/8/2015
New Instructional DVD
How much scatter radiation occurs during an AP chest?
We did this experiment many times with and without grids, at 115 and 85 kV, and at 3 different angles. This one is taken at 90 degrees to the patient.
10
2/8/2015
This one is taken at 45 degrees to the patient.
Natural Background Radiation ­­ 2006
Natural Background Radiation And this one we are calling 0 degrees.
Here are all the doses for 0, 45 and 90 degrees (arrows at 6’) [email protected] and 115@4
Dose exposure due to scatter
from Portable Chest Xrays
� 1R =1 Rad
mR)) = 1/1000 of an R
� 1 milliR (mR
� 1 microR (uR
uR)) = 1/1000 of a mR
milliR/year
/year
� Natural Radiation = 304 milliR
� 304 milliR = 304,000 microR
� 304,000 microR
microR/year
/year = 844 microR
microR/day
/day
This experiment used the arm/hand phantom and a 10x12 CR cassette. We set it up where many techs stand when making a PCXR exposure. This photo and the following image have the cassette at: 45 degrees and 12 feet from the patient.
Dose exposure due to scatter
from Portable Chest Xrays
Angle of
Average
Dose
Chamber Distance Dose #1 Dose #2
(Deg)
(ft)
(microR) (microR) (microR)
90
1
96.0
94.6
95.3
90
2
42.7
42.0
42.4
90
3
21.1
22.0
21.6
90
4
13.3
12.7
13.0
90
5
10.6
9.0
9.8
90
6
6.9
6.1
6.5
45
1
195.5
196.2
195.9
45
2
79.3
80.7
80.0
45
3
38.3
39.2
38.8
45
4
24.3
23.8
24.1
45
5
16.2
17.9
17.1
45
6
11.6
12.0
11.8
45
7
9.4
9.1
9.3
45
8
7.1
6.4
6.8
0
6
34.0
33.1
33.6
0
7
24.5
23.0
23.8
0
8
17.4
16.0
16.7
0
9
14.0
14.2
14.1
0
10
10.5
11.6
11.1
0
11
8.4
8.9
8.7
0
12
6.3
7.5
6.9
0
13
5.3
6.4
5.9
0
14
0.0
0.0
0.0
0
15
0.0
0.0
0.0
0
16
0.0
0.0
0.0
Angle of
Cha mbe r Distance Dose #1 Dose #2
(De g)
(ft)
(microR) (microR)
90
1
316.0
320.0
90
2
125.8
127.2
90
3
68.3
67.6
90
4
42.2
41.0
90
5
27.1
28.3
90
6
19.7
19.7
45
1
744.0
778.0
45
2
295.0
295.0
45
3
150.7
151.2
45
4
98.3
97.6
45
5
66.2
65.2
45
6
48.6
47.4
45
7
33.6
32.7
45
8
27.6
27.5
0
6
76.0
75.1
0
7
50.5
51.8
0
8
39.3
39.8
0
9
32.3
31.9
0
10
25.4
27.0
0
11
22.4
21.8
0
12
17.0
16.9
0
13
14.3
14.4
0
14
12.6
12.5
0
15
10.2
9.9
0
16
8.3
8.2
Chest technique of [email protected] w as used for all
exposures. Ionization Chamber angle is
measured from mid sagittal plane.
Che st technique of 115@4 wa s use d for all
e xposure s. Ionization Chamber angle is mea sured
from mid sa gitta l plane.
Ave ra ge
Dose
(microR)
318.0
126.5
68.0
41.6
27.7
19.7
761.0
295.0
151.0
98.0
65.7
48.0
33.2
27.6
75.6
51.2
39.6
32.1
26.2
22.1
17.0
14.4
12.6
10.1
8.3
An image cannot lie. Even though the scatter dose is way down in the micro R’s, there is enough radiation to make this image –
to make this image – with 1 exposure!!
11
2/8/2015
This photo and the following image was taken with the phantom/cassette 12 feet from the patient directly behind the tube (which is 6 feet from the patient).
If you’re thinking like we were, then you’re wondering how much (if any) of that dose came from back of the tube, not the patient. It turns out that at 12 inches from the backside of the tube the dose was so small that the dosimeter could not read it.
This just proves that a few MicroR is still enough radiation to do the job.
The perfect place to stand when making an exposure is directly behind the tower. You lean your head out while giving the breathing instructions, then move your head back behind the tower while making the exposure. Checking to see if it is wiser to shield a patient in the front or the back for a PA chest x­­ray. Collimated to front or the back for a PA chest x
14x17 with shield and cassette below primary beam.
Off­
Off­Focus Radiation
Art courtesy of “Principles of radiographic Imaging “ by Rick Carlton
12
2/8/2015
Shield and cassette in front.
117 kV @ 2.5 mAs LgM .540
See how much Off­
See how much Off­Focus Radiation actually comes out of the aperature..
actually comes out of the aperature
CR cassette with paper clips spaced every inch, bottom of 14x17 lightfield just above the cassette. None of the primary beam is hitting the cassette.
Cassette blocked with a .5mm lead apron.
117 kV @ 2.5 mAs LgM 0.511
1200 Speed
Shield and cassette in back.
117 kV @ 2.5 mAs LgM 1.53
117 kV @ 2.5 mAs 72 kV @ 20 mAs
LgM 1.23 LgM 1.69
1200 Speed
Off­­Focus experiment with the dosimeter. Off
Ion chamber 36” off floor. Tube 40” and 72” SID. Collimated to 14”x17”.
13
2/8/2015
Started with bottom of light field just above the top of the ion chamber.
Here are the doses from all three experiments.
Leakage Radiation Through Collimators
Height above
ion chamber
in inches
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
85 kV@ 3.2 mAs 115 kV@ 4 mAs 85 kV@ 16 mAs
72" SID
40" SID
72" SID
MicroR's (µR)
MicroR's (µR)
MicroR's (µR)
96.0
72.0
52.0
39.3
31.1
27.6
21.8
18.0
15.6
13.0
11.2
9.9
8.6
7.4
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
239.0
166.1
117.9
90.5
71.1
59.4
50.9
42.8
36.7
31.0
27.1
23.3
20.8
18.7
17.3
15.8
14.6
13.8
12.8
12.6
12.4
12.4
12.2
11.6
11.5
11.0
11.2
10.7
Tube 27” higher (maxed out)
I repeated all 3 experiments using the hand phantom I repeated all 3 experiments using the hand phantom and cassette run at 1200 speed. The bottom of the 14x17 light field was 6” above the top of the cassette.
1035.8
615.4
432.8
391.6
321
296.8
244.6
218.6
180.6
164.2
148.5
133.1
125
111.7
105.5
101.1
97.7
96.2
95.1
94.1
90.8
86.9
82.5
78
74.2
72.4
70.3
66.8
Getting the ESE on the abdomen phantom.
Set­
Set­up for exit dose with the thorax phantom.
14
2/8/2015
Attempting to discover Absorbed (Midline) Dose with my “fake” body phantom using polyethylene blocks and 500cc saline bags.
Anterior Quarter 1.05 R ­­50.7% (+49.3%) Anterior Quarter 1.05 R Posterior Quarter 0.195 R ­­90.8% (+9.2%) Posterior Quarter 0.195 R 85 kV @ 14 mAs 45’’ 14x17 Entrance 2.13 R 0% Middle –
Middle – Midline Dose (MD) 0.469 R ­78% (+22%) Exit 0.051 R ­
Exit 0.051 R ­97.6% (+2.4%) 15
2/8/2015
Under Grid (in bucky) 0.0075 R ­99.6
99.6%
% (+.
(+.4%)
4%)
Peer Reviewed article in the Jan/Feb 2015 Peer Reviewed article in the Jan/Feb 2015 issue of Radiologic Technology, it was proven that increasing SID will decrease patient dose � Entrance surface dose, including backscatter was reduced by 39% was reduced by 39% and effective dose by 41% and effective dose by 41% when the SID was increased from 100 cm (40”) to 140 cm (55”).
� Also the image quality is increased because the magnification and geometric unsharpness are reduced.
Differences in SID’s
� Classic distances are (were) 40” or 44” and 72.”
� Patients are much larger now.
� Typical large patient for abdomen…
� 51” using fluoro table bucky
� 63” using movable table bucky
� 72” using upright bucky
16
2/8/2015
This experiment was to show the difference in dose getting through a .25, .375 and .5 equivalent lead shield (using the .5 as the standard). The tube is set at 40” and is collimated to a 12”x12.”
Here’s a demonstration to show the difference between .25mm and .5mm lead aprons at a distance of 2­­6 ft.
.25mm and .5mm lead aprons at a distance of 2
Done at 90 and 60 degrees to the patient.
The .25 and .375 aprons are letting through anywhere between 1.3 to over 22.3 times more radiation!!
Lead Apron Study, Using Abdomen Phantom w/ meter perpendicular,
meter 2" away from left side. Doses are an average of three different
types of lead aprons.
Lead (mm)
kV
mAs
Dose (mR)
Dose increase
compared to
0.5mm le ad (%)
Dose increase
compared to 0.5mm
lead (x)
None
0.25
0.375
0.5
81
81
81
81
4
4
4
4
0.89
0.04
0.007
0.003
29567%
1233%
133%
296.7
13.3
2.3
None
0.25
0.375
0.5
81
81
81
81
8
8
8
8
1.84
0.08
0.02
0.008
22900%
900%
150%
230.0
10.0
2.5
None
0.25
0.375
0.5
81
81
81
81
16
16
16
16
3.76
0.173
0.043
0.023
16248%
652%
87%
163.5
7.5
1.9
None
0.25
0.375
0.5
102
102
102
102
2
2
2
2
0.91
0.063
0.017
0.01
9000%
530%
70%
91.0
6.3
1.7
None
0.25
0.375
0.5
102
102
102
102
4
4
4
4
1.88
0.137
0.037
0.025
7420%
448%
48%
75.2
5.5
1.5
None
0.25
0.375
0.5
102
102
102
102
8
8
8
8
3.81
0.283
0.093
0.048
7838%
490%
94%
79.4
5.9
1.9
None
0.25
0.375
0.5
125
125
125
125
1
1
1
1
0.79
0.67
0.13
0.03
2533%
2133%
333%
26.3
22.3
4.3
None
0.25
0.375
0.5
125
125
125
125
2
2
2
2
1.61
0.157
0.053
0.04
3925%
293%
33%
40.3
3.9
1.3
None
0.25
0.375
0.5
125
125
125
125
4
4
4
4
3.29
0.34
0.14
0.067
4810%
407%
109%
49.1
5.1
2.1
The abdomen phantom is on top of 6 inches of polyethylene to simulate a 250 lb patient. The roller shield has a .5mm lead.
17
2/8/2015
Comparison of Lead Apron Protection
This yellow apron is .25mm.
Distance Thickness
(ft)
(mm)
0.5
2
0.25
0.5
3
0.25
0.5
4
0.25
0.5
5
0.25
0.5
6
0.25
0.5
2
0.25
0.5
3
0.25
0.5
4
0.25
0.5
5
0.25
Angle
(deg)
90
90
90
90
90
90
90
90
90
90
60
60
60
60
60
60
60
60
Dose
(mR)
0.012
1.595
0
0.834
0
0.546
0
0.338
0
0
0
1.057
0
0.62
0
0.389
0
0
130 X’s more radiation
The cumulative dose through a lead apron during
1 minute of fluoroscopy at various distances. A
phantom is supine with 6 in of polyethylene blocks
under it. In room flouro II is 4in above midline of
phantom. The ion chamber records measurements
perpendicular (90 deg) to the migsagittal plane of
the phantom and 60 degrees off of perpendicular.
Here’s a demonstration that your lead aprons are
made to protect you from scatter radiation only,
not the primary beam.
40” 85 kV @ 16 mAs (medium hip technique)
One .5 mm lead apron covering the R marker
40” 85 kV @ 16 mAs
Two .5 mm lead aprons covering the R marker.
40” 85 kV @ 16 mAs
Three .5 mm lead aprons covering the R marker.
18
2/8/2015
40” 85 kV @ 16 mAs
Four .5 mm lead aprons covering the R marker.
40” 85 kV @ 16 mAs
Five .5 mm lead aprons covering the R marker.
72” 113 kV @ 4 mAs (Average gridded chest)
One .5 mm lead apron covering the R marker.
72” 113 kV @ 4 mAs
Two .5 mm lead aprons covering the R marker.
40” 113 kV @ 4 mAs
Three .5 mm lead aprons covering the R marker.
40” 113 kV @ 4 mAs
Four .5 mm lead aprons covering the R marker.
19
2/8/2015
40” 113 kV @ 4 mAs
Five .5 mm lead aprons covering the R marker.
72” 85 kV @ 3.2 mAs (Average non grid chest)
One .5 mm lead apron covering the R marker.
72” 85 kV @ 3.2 mAs
Two .5 mm lead aprons covering the R marker.
72” 85 kV @ 3.2 mAs
Three .5 mm lead aprons covering the R marker.
20