Linda Nie, Assistant Professor School of Health Sciences Purdue University.
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Transcript of Linda Nie, Assistant Professor School of Health Sciences Purdue University.
![Page 1: Linda Nie, Assistant Professor School of Health Sciences Purdue University.](https://reader035.fdocuments.in/reader035/viewer/2022062318/551b35fa550346d41a8b512d/html5/thumbnails/1.jpg)
Noninvasive In Vivo Measurement of Pb with a Portable XRF
Device
Linda Nie, Assistant ProfessorSchool of Health Sciences
Purdue University
![Page 2: Linda Nie, Assistant Professor School of Health Sciences Purdue University.](https://reader035.fdocuments.in/reader035/viewer/2022062318/551b35fa550346d41a8b512d/html5/thumbnails/2.jpg)
Why portable x-ray fluorescence technology
Approach Results and discussion More work in progress Acknowledgements
Outline
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Portable Multi-metals Fast More sensitive in some cases
Accessible, suitable for large population human studies
Why Portable XRF?
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Soft tissue attenuationIt is difficult to detect signals
through tissue over 5 mm Soft tissue attenuation correction
◦Spectrum to determine the soft tissue thickness
Bone surface/volumn? (mfp in bone: 0.5 mm vs. 25 mm)
Bone Pb Quantification with Portable XRF- Disadvantage
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Schematic plot
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Overall: develop a portable XRF technology to quantify multiple metals in bone and skin
Hardware designselection of tube target, filter combination, and geometry design; selection of parameters
Methodology and algorithm development Consider in vivo situation Radiation risk assessment
Objectives
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Monte Carlo simulations (MCNP) X-ray tube voltage, current, filter combinations;
x-ray tube target, geometry design etc.
Calculate minimum detection limit (MDL)
Approach - Hardware
2 bnMDL ct
( )m
t b
C ppmc
n n
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Approach – calibration
2-A(2)( ) = A(1) exp(- ) (4) exp( (5) )
A(3)
xy x A A x
222
1 ( )i i
i
X y y x
Once the hardware design is determined ……
Method #1: peak fitting and traditional cal.
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Method #2: background subtraction
Calibration – Cont.
21 1 1( ) = K bkg A c B c C
22 2 2(100 ) = K ppm A c B c C
21 1 1( ) = ( ) ( )K net K total A c B c C
= ( ) 100 / (100 )Concentration K net K ppm
K ( ) ( )2 concentration
live time = ( )
total K bkg
K net
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Soft Tissue Thickness Determination
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MC simulation
Experiments
Dosimetry
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Phantom, goat bone, and cadaver bone experiments◦ICP-MS, KXRF
Human studies
Validation of the Technology
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Lucite Thickness (mm)
Detection Limit (ppm)
0 2.31 4.12.04 7.13.08 11.84.08 18.64.92 25.9
Detection limit
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Phantom Concentration
(ppm)
Portable XRF (ppm) KXRF (ppm) ICPMS (ppm)
0mm Lucite 1mm Lucite 2.72mm Lucite
0 -1.05±1.73 0.72±2.30 0.62±7.26 -.068±1.96 0.63±0.20
10 11.3±1.83 12.8±3.07 9.81±7.09 8.97±1.81 11.2±0.71
20 17.2±1.90 17.3±3.15 20.2±7.16 19.6±1.91 16.7±1.89
30 31.3±2.09 29.3±3.30 26.6±7.34 30.6±1.84 36.0±0.89
50 45.4±2.24 45.0±3.49 40.0±7.59 51.8±1.77 72.5±11.7
100 99.9±2.72 96.0±3.96 100±8.16 106±2.16 127±16.0
Bone lead concentration of phantoms using portable XRF, conventional XRF, and ICPMS
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Goat Bone # Portable XRF (ppm) KXRF (ppm)0mm Lucite 1mm Lucite 2mm Lucite
1 19.7±1.95 15.4±3.05 22.2±5.31 23.5±1.64
9 2.73±2.23 0.84±2.72 6.33±5.30 4.5±1.40
12 29.9±2.00 32.3±3.17 30.5±5.32 31.5±1.75
13 13.6±1.79 15.6±2.91 19.1±5.06 12.3±1.49
Comparison of portable XRF and KXRF bone lead measurements for goat bones
(adjusted for Compton peak counts)
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LXRF vs. KXRF for goat bones
0 5 10 15 20 25 30 35
-5
0
5
10
15
20
25
30
35
40
KXRFBare LXRF2mm LXRF
Concentration From KXRF (ppm)
Measure
d C
oncentr
ati
on f
rom
port
able
XR
F
(ppm
)
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Bone KXRF LXRF (0mm) ICPMS ICPMS ICPMS
7202 21.37 1.51E+01
6895 13.17 1.03E+01
6900 22.63 1.30E+01 1.16E+01 9.87E+00 1.13E+01
6918 18.78 1.16E+01
7002 16.56 9.93E+00
7031 20.33 1.10E+01
7131 20.59 1.41E+01 1.23E+01 1.81E+01 1.40E+01
7142 15.72 7.39E+00 9.73E+00 8.03E+00 5.74E+00
7162 18.30 8.45E+00 8.47E+00 8.45E+00 6.82E+00
7168 6.90 3.04E+00 2.28E+00 1.50E+00 2.88E+00
Cadaver bone results
Overestimate backgroundSolution: a. ‘real’ bone phantoms; b. adjustment using MC simulation results;Surface bone? Pb distribution in bone.
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Validation: KXRF vs. Portable XRF
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Radiation Risk Skin dose of ~13 mSv and total body
effective dose of 1.5µSv compared with
Exposure limit of 500 mSv per year to extremities for occupational workers (no limit set for general public) and a typical whole body effective dose of 100 µSv for chest x-ray
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System optimization – customized device Standardize the calibration process (true
bone equivalent phantoms, or MC simulations to adjust for differences)
Validation of the technology with a large human population
Apply the technology for metal epi and metal toxicology study
Bone Sr measurement
More work in progress
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X-ray tube output simulation
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In vivo simulation
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Steven Sanchez, Graduate Student, School of Health Sciences, Purdue University
Aaron Specht, Graduate Student, School of Health Sciences, Purdue University
Dr. Lee Grodzins, ThermoFisher Niton
Dr. Marc Weisskopf, HSPH
Acknowledgement
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Thank you!Questions??
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Cadaver Bone Spectrum
Portable XRF Cadaver Measurement,Pb concentration ~20ppm
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0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 50
500
1000
1500
2000
2500
3000
Goat BonePlaster
Lucite thickness (mm)
Com
pto
n p
eak c
ounrs
(/s
)
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Pilot studies – Methodology and Feasibility
ThermoFisher Niton: XL3t-GOLDD
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1. 100 lbs vs. 3 lbs2. 30 mins vs. 2 min3. Multi-metals
Bone Pb Measurement Quantification with Portable XRF - Advantages