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Noninvasive In Vivo Measurement of Pb with a Portable XRF Device

Noninvasive In Vivo Measurement of Pb with a Portable XRF Device. Linda Nie, Assistant Professor School of Health Sciences Purdue University. Outline. Why portable x-ray fluorescence technology Approach Results and discussion More work in progress Acknowledgements. Why Portable XRF?.

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Noninvasive In Vivo Measurement of Pb with a Portable XRF Device

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  1. Noninvasive In Vivo Measurement of Pb with a Portable XRF Device Linda Nie, Assistant Professor School of Health Sciences Purdue University

  2. Outline • Why portable x-ray fluorescence technology • Approach • Results and discussion • More work in progress • Acknowledgements

  3. Why Portable XRF? • Portable • Multi-metals • Fast • More sensitive in some cases Accessible, suitable for large population human studies

  4. Bone Pb Quantification with Portable XRF- Disadvantage • Soft tissue attenuation It 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)

  5. Schematic plot

  6. Objectives Overall: develop a portable XRF technology to quantify multiple metals in bone and skin • Hardware design selection of tube target, filter combination, and geometry design; selection of parameters • Methodology and algorithm development • Consider in vivo situation • Radiation risk assessment

  7. Approach - Hardware • Monte Carlo simulations (MCNP) X-ray tube voltage, current, filter combinations; x-ray tube target, geometry design etc. • Calculate minimum detection limit (MDL)

  8. Approach – calibration Once the hardware design is determined …… Method #1: peak fitting and traditional cal.

  9. Calibration – Cont. • Method #2: background subtraction

  10. Soft Tissue Thickness Determination

  11. Dosimetry • MC simulation • Experiments

  12. Validation of the Technology • Phantom, goat bone, and cadaver bone experiments • ICP-MS, KXRF • Human studies

  13. Detection limit

  14. Bone lead concentration of phantoms using portable XRF, conventional XRF, and ICPMS

  15. Comparison of portable XRF and KXRF bone lead measurements for goat bones(adjusted for Compton peak counts)

  16. LXRF vs. KXRF for goat bones

  17. Cadaver bone results Overestimate background Solution: a. ‘real’ bone phantoms; b. adjustment using MC simulation results; Surface bone? Pb distribution in bone.

  18. Validation: KXRF vs. Portable XRF

  19. 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

  20. More work in progress • 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

  21. X-ray tube output simulation

  22. In vivo simulation

  23. Acknowledgement • 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

  24. Thank you! Questions??

  25. Cadaver Bone Spectrum Portable XRF Cadaver Measurement, Pb concentration ~20ppm

  26. Pilot studies – Methodology and Feasibility ThermoFisher Niton: XL3t-GOLDD

  27. Bone Pb Measurement Quantification with Portable XRF - Advantages • 100 lbs vs. 3 lbs • 30 mins vs. 2 min • Multi-metals

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