Coherent scattering and matrix correction in bone-lead measurements

Area of Science:

• Medical Physics
• Biomedical Engineering
• Materials Science

Background:

• K shell x-ray fluorescence is crucial for assessing lead in bone.
• The coherent conversion factor (CCF) is vital for accurate lead quantification.
• CCF accuracy depends on matrix composition, scattering angle, and energy.

Purpose of the Study:

• To evaluate CCF variations due to matrix assumptions in lead-in-bone analysis.
• To compare CCF for plaster of Paris versus synthetic apatite bone mineral matrices.
• To quantify the impact of impurities and measurement geometry on CCF.

Main Methods:

• Calculated CCF using relativistic form factors.
• Analyzed published bone compositions.
• Assessed plaster of Paris and synthetic apatite compositions.

Main Results:

• Impurities in plaster, lead presence, non-bone scatter, and geometry have minimal CCF impact.
• Synthetic apatite matrix is a more accurate representation of bone mineral than plaster of Paris.
• CCF is a function of scattering angle, energy, and elemental composition.

Conclusions:

• Synthetic apatite is a superior matrix for calibration standards in lead-in-bone XRF analysis.
• Conventional assumptions regarding CCF constancy require careful consideration of matrix composition.
• Accurate lead quantification in bone benefits from matrix-appropriate calibration.