A new anthropometric phantom for calibrating in vivo measurements of stable lead in the human leg using x-ray fluorescence.
A new anthropometric phantom has been developed for calibrating in vivo measurements of stable lead deposited in bone using x-ray fluorescence. The phantom reproduces the shape of the mid shaft of the adult human leg and is fabricated using polyurethanes and calcium carbonate to produce materials that exhibit the same density, energy transmission, and calcium content as cortical bone, bone marrow, and muscle. The phantom includes a removable tibia fabricated using simulants for cortical bone and bone marrow to which a precise amount of stable lead has been added to cortical bone. The formulations used in fabricating the new anthropometric phantom are much more uniform in density and composition than the conventional phantom made from Plexiglas cylinders filled with plaster-of-Paris. The energy spectrum from an x-ray fluorescence measurement of the phantom using a 109Cd source is indistinguishable from an in vivo x-ray fluorescence measurement of the human leg, demonstrating that the materials used in the phantom exhibit the same radiological properties as human tissue. Likewise, results from x-ray fluorescence measurements of the phantom exhibit the same positional dependency as the human leg and vary by approximately 36% when, for example, the phantom containing 54 ppm of stable lead in the tibia was rotated by only 15 degrees. The detection limit for a 30 min 109Cd K shell x-ray fluorescence in vivo measurement is approximately 20 ppm determined from a background measurement using the new phantom containing no added lead in the muscle, bone, or bone marrow. The new anthropometric phantom significantly improves in vivo x-ray fluorescence calibration measurements by (1) faithfully reproducing the anatomy of the human leg, (2) having components that exhibit radiological properties similar to that of human tissue, and (3) providing a realistic calibration standard that can be used for in vivo x-ray fluorescence intercomparison measurements.
Spitz
H
H
University of Cincinnati, Department of Mechanical, Industrial, and Nuclear Engineering, OH 45221-0072, USA. hspitz@uceng.uc.edu
Jenkins
M
M
Lodwick
J
J
Bornschein
R
R
D000328:Adult; D001853:Bone Marrow / Q000737:chemistry; D001842:Bone and Bones / Q000737:chemistry; D002118:Calcium / Q000032:analysis; D002138:Calibration; D002356:Cartilage / Q000737:chemistry; D006801:Humans; D007854:Lead / Q000032:analysis*; D007866:Leg; D018482:Muscle, Skeletal / Q000737:chemistry; D019047:Phantoms, Imaging; D011140:Polyurethanes; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012867:Skin / Q000737:chemistry; D013052:Spectrometry, X-Ray Emission / Q000379:methods; D013977:Tibia / Q000737:chemistry
D011140:Polyurethanes; D007854:Lead; D002118:Calcium