The measurement of Pb in bone by X-ray fluorescence using ¹⁰⁹Cd gamma -ray to excite K-shell X-rays is considered. Improvements to the basic system performance were made by changing the design of the source collimator and by including data from the Pb K beta _1,3 photopeaks, having used pile-up rejection to reduce background in their region of the spectrum. The summed variances for eight sample measurements are given: two each of four plaster-of-Paris phantoms embedded in wax.