Principle of proton and heavy ion radiotherapy:
Protons are particles with positive charge after stripping off electrons from hydrogen atoms; heavy ions are nuclei or ions with large atomic weights such as carbon, neon and silicon. Proton and heavy ion technology is a kind of radiotherapy, which is internationally recognized as the cutting-edge technology of radiotherapy. Proton and heavy ion belong to the same particle line, which is different from the traditional photon line, and the particle line can form the energy Bragg peak, which is able to reduce the damage to the healthy tissues at the same time of focusing on the tumor and blasting.
Representing the highest technology and future trend of radiotherapy compared with the traditional radiotherapy that has been carried out for more than a century, proton heavy ion therapy has been carried out only in a few countries such as Germany, Japan and the United States as well as our country due to technical and price factors, and there are only dozens of particle devices for medical use worldwide.
Radiation therapy, as a classical tumor physical therapy, has a history of more than 100 years, and the most common radiation therapy techniques are: stereotactic conformal radiotherapy (3DCRT) and intensity-modulated radiotherapy (IMRT). About 70% of tumor patients need to receive radiation therapy at some stage of their disease course, and it can be said that radiation therapy has become one of the indispensable means of tumor treatment.
And the emergence of proton and heavy ion radiotherapy has brought modern radiation therapy into a new era of development. Previously commonly used radiation therapy, the use of X-rays, that is, electronic lines; and proton heavy ion therapy, the use of proton lines or heavy ion lines, the ray of the particle mass is greater, the killing effect on the tumor is also more powerful. Proton, is the hydrogen atom lost an electron particle; heavy ion, is carbon, neon, silicon and other atomic weight of the atom lost one or several electrons after the particle.
Currently, the tumor radiotherapy community generally believes that proton heavy ion therapy through the integration of high-energy physics, gas pedal manufacturing, computers, automated control and other new technologies applied to tumor imaging, radiotherapy planning, implementation and quality control, so that the accuracy of tumor radiotherapy to reach today's highest level, not only effectively kill tumor cells, but also maximize the protection of the surrounding healthy tissues, with high precision, short course of treatment, It has the advantages of high precision, short treatment course, good curative effect and small side effects.
The rays used in conventional radiotherapy are photons (e.g., high-energy X-rays, 60Co rays, etc.), which have a large amount of attenuation of energy after penetrating human tissues, which not only affects the dose distribution of the tumor target area, but also leads to a large amount of radiation damage to the surrounding tissues. Proton and heavy ion rays, on the other hand, release very little dose in the process of entering the human body, but when they reach the tumor target area, all the energy is released, forming the so-called Bragg peak, which is similar to the "stereotactic blast" in the tumor area, i.e., the target area of the tumor receives a larger dose of radiation, while the damage to the surrounding tissues is reduced to a minimum.
Heavy ion radiotherapy uses particle rays with higher energy than protons (currently the most commonly used is carbon ions), which can effectively kill anoxic or radiotherapy-resistant tumor cells, and has a killing effect on tumor cells of all cell cycles.
Protons or carbon ions are accelerated to about 70% of the speed of light by a synchrotron, and these ion rays are ejected into the human body. Before reaching the tumor lesion, not much energy is released from the rays, but after reaching the lesion, the rays will instantly release a large amount of energy, forming a trajectory of energy release called the "Bragg Peak," which makes the whole treatment process similar to a tumor-specific treatment, and it is also called the "Bragg Peak" treatment. The whole treatment process is like a "three-dimensional directional blast" for the tumor, which can irradiate the tumor lesion strongly and avoid irradiating the normal tissues at the same time, so as to maximize the therapeutic effect.
Internationally recognized, the most advanced radiotherapy technology is proton heavy ion therapy. It is the most advanced radiotherapy technology in the world, which can provide strong irradiation to tumor lesions while avoiding irradiation of normal tissues to maximize the therapeutic effect of radiation therapy on solid tumors. According to the international clinical statistics, it has better curative effect on head and neck, brain, prostate, soft tissue, lung, liver and other parts of the tumor, and it has significant effect on some cancers that are difficult to be operated and cured by conventional radiotherapy. Proton therapy has a wide range of indications, including benign and malignant tumors of brain (meningioma, brain metastases, pituitary tumor, glioma, acoustic neuroma, craniopharyngioma, etc.), spinal cord tumors, cerebrovascular diseases (cerebral arteriovenous malformation, cavernous hemangioma, etc.), head and neck tumors (nasopharyngeal and oropharyngeal cancers, etc.), chordoma and chondrosarcoma of the base of the skull, ocular lesions, thoracic and abdominal tumors, pediatric tumors, etc., and it also has a better effect. The clinical data of foreign countries show that proton therapy has good curative effect. Foreign clinical treatment data show that the effective rate of proton therapy for tumors is as high as 80%, which is evaluated as the treatment method with the best efficacy and the least side effects by the high-energy physics and medical circles.
Introduction of proton deviceThe proton therapy system is a set of huge, complex and precise high-tech equipment. The whole set of equipment consists of proton gas pedal, beam transport system, beam distribution system, dose monitoring system, patient positioning system and control system, covering an area of 70 meters long. One of its core components is the cyclotron, which is used to generate high-energy proton beams; the gas pedal magnet has a diameter of 434 centimeters and is 210 tons in diameter. It emits a proton beam with an energy of up to 230 MeV, enough to treat tumors at any depth in the body. For clinical treatment, the proton beam is introduced through a series of devices into a specialized treatment room and into a rotating treatment rack. The rack is a huge rotating device that controls the projection and occupies three floors of space. It can project the proton beam in any direction to the patient's tumor area in the comfort of the patient's lying down position and guarantees the accuracy within one millimeter. The proton beam used for treatment also needs to be finely adjusted according to the patient's lesion, so that it meets the needs of the treatment in order to achieve the purpose of optimal dose distribution. Therefore, the proton therapy device is equipped with an irradiation system to adjust and change the beam. In addition, in order to make such a large and sophisticated complex equipment operate accurately and reliably, the proton therapy device is equipped with a perfect safety and control system to ensure the safety of patients and staff.
The main advantages of proton therapy for cancer treatment include: tumor proximity to vital organs, so that patients can get the best treatment results and vital organs can be protected; if the tumor recurs, patients will have the opportunity to receive proton therapy again; significant reduction of short-term and long-term side effects; improvement of the quality of life of patients with cancer; significant reduction of the impact on the development of developing children and adolescents; significant reduction of the risk of secondary cancers. cancer.
Indications of proton therapy:
1. Head and neck tumors: meningioma, glioma, craniopharyngioma, pituitary tumors, chordoma of the base of the skull, chondrosarcoma of the base of the skull, vestibular nerve sheath tumors, nasopharyngeal cancer, malignant tumors of the nasal cavity and nasal sinuses, parotid malignancies, oropharyngeal cancers, oral malignancies, adenoid cystic carcinomas, malignant melanomas, soft-tissue sarcomas, angiogenic exothelial tumors, recurrent malignant tumors of the head and neck, head and neck cancers, and other malignancies. malignant tumors of head and neck, medulloblastoma, ventricular meningioma, facial fibrosarcoma, cavernous hemangioma, intracranial germ cell tumor, vascular endothelial cell tumor, neurofibroma, teratoma, carcinoma of the root of the tongue, gingival carcinoma, giant cell tumor of the bone, laryngeal carcinoma, lymphoma, primitive neural ectodermal tumors of PNET.
2. Thoracic tumors: lung cancer, malignant mediastinal tumors including malignant thymoma, malignant thoracic wall tumors , malignant pleural mesothelioma, metastatic lung tumors, mediastinal lymph node metastatic tumors, esophageal cancer, pancreatic cancer, breast cancer, epithelioid sarcoma, Ewing's sarcoma, non-Hodgkin's lymphoma.
3. Tumors of the abdomen, pelvis and other parts: liver cancer, gallbladder cancer, cholangiocarcinoma, extrahepatic cholangiocarcinoma, pancreatic cancer, prostate cancer, endometrial cancer, uterine cervix cancer, spinal cord tumors, sacrococcygeal chordoma/chondrosarcoma, bone tumors, renal carcinoma, ovarian cancer, smooth muscle sarcoma, soft tissue sarcoma, recurrent abdominal and pelvic tumors, and primitive neurilegal ectodermal tumors PNET.