Researchers have developed a novel X-ray fluorescence ghost imaging (XFGI) technique that allows imaging of heavy elements inside human-scale objects without the need for radioisotopes. This method uses a conventional laboratory X-ray source and a single-pixel detector, making it a safer and more accessible alternative to current radioisotope-based techniques, which pose safety and waste management challenges. The technique is based on the principle of ghost imaging, where the correlation between a structured illumination pattern and the total detected signal allows for the reconstruction of the object's image.

The advance is significant because current techniques for deep detection of heavy elements, such as positron emission tomography (PET) or single-photon emission computed tomography (SPECT), require the injection of radioisotopes into the patient. This involves exposure to ionizing radiation and the need for specialized facilities for their production and handling. The proposed XFGI avoids these drawbacks by using an external X-ray source and the characteristic fluorescence of heavy elements, opening the door to non-invasive and safer medical diagnostics and security applications.

In the demonstration, the team successfully imaged elements with an atomic number Z greater than 50, such as gadolinium (Gd) and iodine (I), embedded in a 10 cm thick soft tissue phantom. The spatial resolution achieved was 1.5 mm, with a radiation dose comparable to that of a standard computed tomography (CT) scan. This level of detail and penetration capability are crucial for biomedical applications, such as detecting contrast-enhanced tumors or characterizing metallic implants, without the risks associated with radioisotopes. The next step will be to optimize the technique to further reduce the dose and improve image acquisition speed, bringing it closer to clinical application.