Proton therapy is an advanced form of cancer treatment using protons. In recent years it has gained popularity due to its advantages over conventional radiotherapy, since the characteristics of these particles that form the atomic nucleus allow almost all their energy to be deposited in the tumor cells with hardly any effect on healthy tissue. However, in order to be able to plan the treatment correctly, medical images of the patient are required.
At present, these images are obtained with X-rays through so-called computed axial tomography (CT) scans. However, the subsequent treatment is performed with proton beams and not with X-rays, which introduces uncertainties when planning the treatment and calculating the doses correctly.
The new scanner allows imaging directly with protons and is the first device of its kind to be developed in Spain. "Although it is currently a preclinical scanner that has obtained images of small mannequins, the results have been promising and have demonstrated the feasibility of the concept," says Enrique Nácher, CSIC scientist at IFIC and director of this project.
The research team has combined an array of tracking detectors and a high-energy resolution scintillator to detect the residual energy of protons. It has used several dummies that were irradiated with protons at a proton therapy center in Krakow, Poland, and measured the dummies at different angles to obtain filtered back-projection reconstructed images, used to determine the scanner's capabilities and validate its use as a proton computed tomography (proton-CT) scanner.
According to the results of the paper now published in The European Physical Journal Plus, the scanner can produce medium-high quality images, with resolving power comparable to other state-of-the-art scanners. In the researchers' view, if the system is scaled appropriately it could be used to image patients prior to proton therapy, significantly improving accuracy in treatment planning. "This would make it possible to optimize dose deposition in cancerous tissue, minimizing exposure of healthy tissue," explains the IFIC researcher.
Reuse of resources
The proton scanner developed through the collaboration between the Institute of Corpuscular Physics, the Institute of Structure of Matter and the Complutense University of Madrid has been built by reusing instrumentation and materials from old prototypes of other nuclear physics projects that were no longer useful for their original purposes. This approach has maximised the reuse of resources without the need to invest in new instrumentation, promoting the efficient and sustainable use of existing resources, according to its promoters.