With the support of the leaders of the Sichuan Cancer Hospital and radiation oncology department, in April 2018, our hospital sent one doctor named Mei Feng and one medical physicist named Ke Yuan to be the visiting scholar in Italian National Centre for Oncological Hadrontherapy (CNAO). We will study in CNAO for a three-months and one-year research program respectively. And CNAO is very enthusiasm and provides very convenient conditions for our study.
The National Centre for Oncological Hadrontherapy (CNAO, sited in Pavia, Italy) was established in 2000 by the Italian Health Ministry, which was completed at the end of 2013. It is one of the four centers in the world that have “dual accelerators”, which can accelerate both protons and carbon ions, and it was mainly used to treat radiation-tolerant and inoperable tumors. CNAO provides the highest quality radiation therapy for cancer patients in Italy, and plays a pivotal role in the entire European cancer.CNAO began construction in 2005 and lasted five years (Figure 1: Top view of the area occupied by CNAO). Since 2014, the CNAO Center has received patients from all over Italy and abroad every year, and has established a comprehensive information network with more than 3,000 patients each year.
Figure 1. Top view of the area occupied by CNAO. In front the hospital building and the entrance, in the back the power station and the roof of the synchrotron vault.
CERN(European Organization for Nuclear Research) designed a European synchrotron to produce carbon ions and protons optimized for cancer therapy. This study was called the Proton Ion Medical Machine Study (PIMMS) and was completed in 2000. TERA planned a more compact version of the synchrotron called PIMMS / TERA which later evolved into the final CNAO version of the machine built in Pavia.It has the most advanced active scanning technology (pen pencil bundle). CNAO now has 3 treatment rooms and one laboratory room (Figure 2).Proton therapy is effective because its energy can be released at a predetermined depth, called the Bragg peak (Figure 3. Bragg peak for proton therapy). The proton beam passes through the normal tissue in the human body and reaches the tumor tissue to instantly release a huge dose, killing the cancer cells, and the energy after the tumor tissue quickly falls to zero, maximally protecting the normal organs. The intensity-modulated proton therapy (IMPT) performed by the pencil beam scanning is very accurate in its effectiveness and dose-conformity. It is the best way of proton therapy at present (Figure 4. Examples of proton therapy).
Figure2. Treatment rooms in CNAO
Figure 3. Bragg peak of proton therapy
Figure 4. Examples of proton therapy (left: proton, right: photon)
At present, we have been working and studying in the CNAO Center for more than one month. CNAO treats approximately 60 patients per day, and about 40% of the patients are treated with protons. The main diseases are tumors of central nervous system, childhood carcinoma, prostate carcinoma，chordoma, sarcoma and adenoid cystic carcinoma, which are tolerated by radiotherapy and cannot be treated surgically. The CNAO Center has a total of 7 doctors and 8 physicists who has worked about 10 hours per day to conduct new patient visit, CT simulation, treatment planning and follow up. We follow the clinical experts of different sub-specialties to study and discuss with them, exchange treatment opinions, and design target delineation and make treatment plans according to the specific conditions of patients (Figure 5 and 6)
Figure 5. Doctor mei feng contouring the tumor target and making the treatment decision with the Italy experts
Figure 6. Medical physicist ke yuan discussing the generating treatment planning with the Italy experts
Since the treatment principles of protons and heavy particles are very different from traditional photons, it takes a lot of experience to outline the target area and make treatment plans. The close cooperation between doctors and physicists is very important. Real-time monitoring during each treatment process, regular scanning of CT simulation during the treatment process, monitoring the changes of radiation dose, ensuring high precision of treatment from all aspects, not only to ensure that the tumor receives the radical dose, but also to protect the normal organs to the greatest extent.
Finally, we are very fortunate to have the opportunity to study and work at the world's top proton heavy ion treatment centers, and deeply admire the professionalism of international experts. Here, we’d like to thanks to our hospital managed by the professor Lang, the director of our department and also the Italian expert lucia to give us such a good opportunity to study here. We will continue studying in depth and striving to cooperate with the CNAO Center to conduct clinical research and contribute to the development of our hospital.
