Portable Cd-109/CZT KXRF system for in vivo bone lead measurement: a field-deployable method for assessing cumulative lead exposure

Background Bone lead (Pb) serves as a strong indicator of cumulative Pb exposure and reflects long-term body burden. K-shell X-ray fluorescence (KXRF) remains the accepted method for in vivo bone Pb assessment, yet traditional systems rely on high-purity germanium detectors that require cryogenic cooling. These physical constraints limit access to cumulative exposure measurement in many populations. Objective The study examined a portable KXRF system with a room-temperature detector to determine whether its performance matches the detection capability of laboratory-based HPGe KXRF. The study assessed detection limits and evaluated agreement with reference bone Pb measurements. Methods Pb-doped bone phantoms with concentrations from 0 to 100 ppm established calibration relations for the portable system. Thirty measurements of a 0-ppm phantom established a baseline detection limit that was then normalized to reflect performance under conditions that match standard HPGe acquisition parameters. Cadaver tibias with known Pb content were evaluated, and results were compared with values from an established benchtop XRF method. Results The portable system produced linear calibration results across the full phantom range (R² = 0.987). Cadaver tibia results aligned with the benchtop XRF values (R² = 0.777). The normalized detection limit reached the 2–3 ppm range, which mirrors the sensitivity of HPGe systems despite the absence of cryogenic cooling. Significance The findings show that portable KXRF can support assessment of cumulative Pb exposure in settings without access to laboratory-based HPGe instruments. The system expands opportunities for bone Pb evaluation in clinical environments and field studies and strengthens exposure assessment in populations with limited access to specialized facilities. Impact This study shows that bone lead can be measured with a portable KXRF system that matches the sensitivity of laboratory HPGe instruments. The work addresses a gap in exposure science because cumulative lead burden remains difficult to quantify outside specialized facilities. By removing cryogenic cooling and fixed laboratory requirements, this system supports real-world exposure assessment in community, clinical, and field settings. The results create a practical path toward broader surveillance of long-term lead exposure, especially in populations and environments where traditional KXRF instruments are not feasible.