XRF exposure can be achieved using which isotope listed in the source material?

XRF exposure can be achieved using which isotope listed in the source material?

• A. Cobalt-57
• B. Cesium-137
• C. Cadmium-109
• D. Americium-241

Answer: (C)

XRF exposure works by using a radioactive source to emit X-rays that excite the atoms in a sample, causing them to emit their own characteristic X-rays that reveal what elements are present. Cadmium-109 is listed for this purpose because its emission includes relatively low-energy X-rays (such as photons that lead to Ag-related X-ray lines around 22 keV) that efficiently excite a wide range of elements relevant to XRF analysis. This energy range is well-suited for producing clear, detectable fluorescence without requiring heavy shielding or dealing with very high-penetration radiation. That practicality is why cadmium-109 is the isotope used for XRF exposure in the source material. The other isotopes emit radiation energies or types that are less ideal for XRF excitation—more suited to calibration, general gamma exposure, or higher-energy paths—not the kind of excitation typical for XRF measurements.

XRF exposure works by using a radioactive source to emit X-rays that excite the atoms in a sample, causing them to emit their own characteristic X-rays that reveal what elements are present. Cadmium-109 is listed for this purpose because its emission includes relatively low-energy X-rays (such as photons that lead to Ag-related X-ray lines around 22 keV) that efficiently excite a wide range of elements relevant to XRF analysis. This energy range is well-suited for producing clear, detectable fluorescence without requiring heavy shielding or dealing with very high-penetration radiation. That practicality is why cadmium-109 is the isotope used for XRF exposure in the source material. The other isotopes emit radiation energies or types that are less ideal for XRF excitation—more suited to calibration, general gamma exposure, or higher-energy paths—not the kind of excitation typical for XRF measurements.