Which material is used in Dual Photon Absorptiometry (DPA)?

• A. Radium-226
• B. Gadolinium-153
• C. Cesium-137
• D. Cobalt-60

Answer: (B)

Dual Photon Absorptiometry (DPA) utilizes Gadolinium-153 as the radioactive source for measuring bone mineral density. This isotope emits gamma photons that penetrate bone and soft tissue, allowing for the absorption characteristics of the different materials to be analyzed. The choice of Gadolinium-153 is particularly significant because it offers optimal energy levels that enable precise assessments of bone density, which is crucial for diagnosing conditions like osteoporosis.

The use of Gadolinium-153 in DPA distinguishes it from other isotopes that are less effective for this type of analysis. Each of the other materials listed either does not emit the appropriate photon energy required for precise bone density measurements or has been largely replaced by more advanced techniques. This makes Gadolinium-153 the standard choice for the DPA method used in bone densitometry.