X-ray tomography is an incredibly useful diagnostic tool in various sectors of medicine. However, the typical radiation dose the patient absorbs during a ct scan is quite high, so that less informative tools must be often used instead. A drastic reduction of the radiation dose would open x-ray tomography to vast new applications, e.g. preventive medicine.

In this project we will use techniques adapted from quantum mechanics to achieve a radiation reduction in CT scans. Very preliminary calculations suggest that at least a tenfold reduction in radiation dose might be possible. The promise of the quantum techniques stems from the fact that they are well suited to extract complete information from the detected radiation, making use of the information at a single-photon level of x-rays. In contrast, the conventionally used algorithms do not take into account the quantised nature of the radiation, which is a rough approximation for highly energetic electromagnetic radiation as x-rays, especially when quantisation noise becomes relevant at low radiation doses. Single photon x-ray detectors have recently started to be used in commercial CT scanners, so the technology for this “quantum leap” is available. Indeed, our method does not require a hardware modification of the existing tomography machines, but just a change of the data processing methodology, namely of the machines’ software.

In more detail, the project goal is to adapt ‘quantum tomography’ to medical tomography. ‘Quantum tomography’ is a procedure that allows an experimentalist to recover the quantum state of a system, i.e. its wavefunction, from repeated measurements on the system. The name “tomography” is used because the first proposals for this procedure used the same mathematical tools (the Radon transform) as medical tomography. However, newer and more sophisticated tools were later developed, starting from a mathematical breakthrough achieved in our research group in Pavia.

In this project we propose to apply these new tools back to medical tomography, closing the loop: from medical tomography we obtained the first quantum tomography, now from the new quantum tomography we want to obtain a new medical tomography.