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Mach 2006 Bureau of Radiological Health
Decision Made at Start of QA Program
• Test all equipment in manual mode– AEC equipment mostly found in hospitals and
large radiology suites– Facilities equipped with AEC equipment
required to have manual technique charts for times when AEC not functioning
– NJ test phantom could not be used to simulate patient anatomy in AEC mode
– Design of Victoreen 4000 meter prevents measuring exposure parameters in AEC mode
Mach 2006 Bureau of Radiological Health
Affect on ESE Numbers?
• Physicists have raised concerns that our tests do not reflect “reality” at sites using AEC exposures
• Bureau agreed that the time was right to re-evaluate its testing protocols for AEC radiographic machines and established a pilot study
Mach 2006 Bureau of Radiological Health
Goals of Study
• Measure ESE utilizing both manual and AEC exposure techniques
• Determine if there is correlation or variance in the measured ESEs
Mach 2006 Bureau of Radiological Health
Estimate of AEC Population
Machines Subject to QA 4,810
Estimate of Machines w/AEC 1,105
Percent w/ AEC 23%
Mach 2006 Bureau of Radiological Health
Pilot Study Testing Protocol
• Verify that facility has manual technique charts available for AEC units tested
• Ensure that radiographic machines chosen for study have functioning AEC and are stable by testing kVp, mAs and timer linearity and accuracy
• Evaluate ESE for AP Lumbosacral Spine exposures at 40” SID
Mach 2006 Bureau of Radiological Health
Testing Setup
• Utilized CDRH NEXT Phantom simulating 21 centimeter patient
• Utilized a calibrated Radcal MDH 1015-X with 10X5-6 Ion Chamber. Chamber setup 9” above the phantom to eliminate scatter affects
• Measured mAs, ms, mR and ESE exposures using facility provided manual techniques
Mach 2006 Bureau of Radiological Health
Testing Setup
• Repeated measurements using AEC technique factors and center sensor
• Four exposures were taken in each mode and average values were calculated
• Calculated ESE measurements in both modes and compared differences
Mach 2006 Bureau of Radiological Health
Lumbar AP ESE For AEC Equipped X-ray Machines
And Its Manual Technique Comparison
LOCATION: DATE: 1/20/2006
FACILITY # ********* REG# 706839
Room A
SECTION SYSTEM TYPE: FILM
INSPECTOR: MGM
A. AEC USED: YES AEC OPERATIONAL: YES
B. MANUAL TECHNIQUE PRESENT: YES
C. X-RAY SYSTEM CHECK
SET KVPSET mA(s)
SET TIME
75 32 n/a
EXPOSURE DATA
TEST # Peak kVp mR ms % ms Error mAs
1 73.14 400.900 46.0 #VALUE! n/a
2 73.47 403.000 45.8 #VALUE! n/a
3 73.74 403.000 46.1 #VALUE! n/a
4 73.50 403.000 45.8 #VALUE! n/a
Avg 73.46 402.475 45.9 #VALUE! 0.00
COVAR 0.003 0.0030.00
3 xxxx #DIV/0!
PASS? TRUE TRUETRU
E #VALUE! #DIV/0!
Mach 2006 Bureau of Radiological Health
F. MANUAL TECHNIQUE CHART
TECHNIQUE CHART POSTED/ AVAILABLE? Y
kVp mAs mA mS
75 32 n/a n/a
EXPOSURE DATA
TEST # mS mR
1 45.7 760
2 45.4 759
3 45.5 761
4 45.9 760
AVG 45.625 760
COVAR 0.005 0.001
QTY UNITS
SFPD 100 cm
F 41.3 cm
AVG EXPOSURE 760 mR
ESE 441.68 mR
Mach 2006 Bureau of Radiological Health
G. AEC TECHNIQUE
kVp Set Note
75 80 kvp auto select
EXPOSURE DATA
TEST # mR ms mAs
1 583.00 46.6 24.8
2 606.00 49.1 25.7
3 602.00 48.4 25.6
4 614.00 49.6 26.1
Avg 601.25 48.425 25.55
COVAR 0.02 0.027 0.021
QTY UNITS
SFPD 100.00 cm
F 41.30 cm
AVG EXPOSURE 601.25 mR
ESE 349.42 mR
H. ESE DIFFERENCE CALCULATION
EXPOSURE TECHNIQUE
Avg ESE Dose
Difference
% DIFFERENCE
mR mR
MANUAL TECHNIQUE 441.68xxxxxxxxxx xxxxxxxxxxx
AEC 349.42 92.26 20.89
Mach 2006 Bureau of Radiological Health
Composition of Study
• 17 machines tested at four facilities
• 2 machines discarded from study due to malfunctioning AEC
• 5 machines used CR image receptors
• 10 machines used film systems
Mach 2006 Bureau of Radiological Health
Avg kVp Manual AEC Avg mAs Avg mAs ESE ESE mR %
Test # Measured kVp kVp Manual AEC Manual AEC Difference Difference
1 75.5 75.0 75.0 32.0 10.5 520.4 185.5 334.9 64.4
2 76.4 75.0 75.0 32.0 18.8 543.0 322.7 220.3 40.6
3 77.3 75.0 75.0 25.0 16.1 301.8 194.8 106.9 35.4
4 73.5 75.0 75.0 32.0 25.6 441.7 349.4 92.3 20.9
5 73.6 75.0 75.0 32.0 21.1 520.7 278.7 242.1 46.5
6 76.5 75.0 75.0 40.0 13.0 580.9 189.9 391.0 67.3
7 70.8 75.0 75.0 50.0 33.7 442.7 262.8 179.9 40.6
8 78.4 76.0 76.0 64.0 8.4 895.0 107.4 787.6 88.0
9 75.6 76.0 76.0 40.0 13.3 947.3 198.3 749.0 79.1
10 76.2 76.0 76.0 40.0 15.5 639.3 239.3 400.0 62.6
11 77.3 76.0 76.0 40.0 26.7 402.4 261.2 141.2 35.1
12 69.8 75.0 75.0 50.0 28.8 412.3 243.7 168.7 40.9
13 76.8 75.0 75.0 25.0 14.5 350.8 199.4 151.3 43.1
14 77.4 76.0 76.0 50.0 12.1 561.1 134.1 427.0 76.1
15 72.7 70.0 70.0 50.0 33.6 531.8 360.8 171.0 32.2
AVG 75.2 75.0 75.0 40.1 19.4 539.4 235.2 304.2 51.5
Max 78.4 76.0 76.0 64.0 33.7 947.3 360.8 787.6 88.0
Min 69.8 70.0 70.0 25.0 8.4 301.8 107.4 92.3 20.9
Raw Data
Mach 2006 Bureau of Radiological Health
Summary Of Results
Difference in ESEManual vs AEC
(mR) %
Range 92-788 21-88
Average 304 52
Mach 2006 Bureau of Radiological Health
Summary Data
Avg kVp Manual AEC mAs mAs ESE ESE mR %
Test # Measured kVp kVp Manual AEC Manual AEC Difference Difference
All
AVG 75.18 75.00 75.00 40.13 19.43 539.40 235.20 304.20 51.51
Max 78.35 76.00 76.00 64.00 33.65 947.29 360.75 787.62 88.00
Min 69.84 70.00 70.00 25.00 8.38 301.77 107.37 92.26 20.89
Film
AVG 74.76 75.10 75.10 36.80 19.39 467.53 236.11 231.42 47.58
Max 77.41 76.00 76.00 50.00 33.65 580.87 349.42 427.01 76.10
Min 69.84 75.00 75.00 25.00 10.48 301.77 134.10 92.26 20.89
CR
AVG 76.03 74.80 74.80 46.80 19.50 683.13 233.38 449.76 59.38
Max 78.35 76.00 76.00 64.00 33.58 947.29 360.75 787.62 88.00
Min 72.66 70.00 70.00 40.00 8.38 402.36 107.37 141.21 32.16
Mach 2006 Bureau of Radiological Health
Summary Of ResultsDifference in ESEManual vs AEC
(mR) %
All 92-788 21-88Film 92-427 21-76
Ran
ge
CR 141-788 32-88All 304 52Film 231 48
Average CR 450 59
Mach 2006 Bureau of Radiological Health
ESE Difference (Manual vs AEC)
48
5952
0.00
10.00
20.00
30.00
40.00
50.00
60.00
70.00
80.00
90.00
100.00
1 2 3 4 5 6 7 8 9 10Test #
% D
iffer
ence
Film CR Average
Mach 2006 Bureau of Radiological Health
Reasons for Variance?
• Manual Technique Charts Not Always Accurate– 5 machines not capable of being set at recommended
technique factors
– 3 machines varied by 5 kVp or more between manual and AEC technique settings
• CDRH phantom not a perfect match for manual technique evaluation– 21 cm patient vs. 23-24 cm Techniques
Mach 2006 Bureau of Radiological Health
Reasons for Variance?
• AEC more efficient than manual techniques– For Same kVp settings, mAs was 2 to 8 times
less than manual counterpart
Mach 2006 Bureau of Radiological Health
Where Do We Go From Here?
• Joint BRH/Physicist effort to improve the accuracy of manual technique charts?
• Joint BRH/Physicist effort to develop an AEC test protocol including valid test phantom(s)?
Mach 2006 Bureau of Radiological Health
BRH Preliminary Tests on Alternative Phantom Materials
• CDRH Phantom not ideal and not practical
• Suggestion from physicists and other state programs that copper or aluminum could simulate lumbar spine phantom
• BRH conducted abbreviated tests using two different thicknesses of copper: 2.4 mm and 2.0 mm
Mach 2006 Bureau of Radiological Health
Lucite 2.4 mm 2.0 mm Lucite 2.4mm 2.0mm mR mR % Diff % Diff
Phantom Cu AEC Cu AEC Phantom Cu AEC Cu AEC 2.4 2 2.4 mm CU 2.0mm CU
Test # mAs mAs mAs ESE ESE ESE diff diff ESE ESE
1 8.38 14.40 8.10 107.37 169.12 90.66 -61.75 16.71 -58% 16%
2 13.30 21.70 12.00 198.32 288.25 160.40 -89.93 37.92 -45% 19%
3 15.50 22.50 12.50 239.29 301.62 164.47 -62.33 74.82 -26% 31%
4 26.73 20.90 11.90 261.15 199.75 106.21 61.40 154.94 24% 59%
5 28.83 47.80 22.50 243.65 387.05 184.23 -143.40 59.42 -59% 24%
6 14.48 10.90 6.81 199.44 149.66 92.33 49.78 107.11 25% 54%
7 12.05 12.90 6.60 134.10 130.76 68.00 3.34 66.10 2% 49%
8 33.58 50.50 24.80 360.75 458.53 228.40 -97.78 132.35 -27% 37%
Ave 19.10 25.20 13.15 218.01 260.59 136.84 -42.58 81.17 -20% 36%
Max 33.58 50.50 24.80 360.75 458.53 228.40 61.40 154.94 25% 59%
Min 8.38 10.90 6.60 107.37 130.76 68.00 -143.40 16.71 -59% 16%
ESE Difference Lucite vs Copper
Mach 2006 Bureau of Radiological Health
Summary Of Results
Difference in AEC ESELucite vs Copper
(mR) %
2.4mm
-143 to 62 -59 to 25
Ran
ge
2.0mm
17 to 155 16 to 59
2.4mm
-43 -20
Average 2.0
mm81 36
Mach 2006 Bureau of Radiological Health
ESE Difference Copper vs Lucite Phantom Materials
-80%
-60%
-40%
-20%
0%
20%
40%
60%
80%
1 2 3 4 5 6 7 8
Test #
% D
iffe
ren
ce% Diff 2.4 mm CU ESE % Diff 2.0mm CU ESE