Iodine 125 Particles (Particle Knife) for Tumor Treatment
In the past 20 years, with the rapid development of science and technology, the high-tech crystalline “particle knife” was born. In 2000, Japan, Korea and other countries carried out this technology one after another, and at the same time, it has attracted the high attention of China’s medical profession.
”Particle Knife” is the latest means of treating tumors based on the latest computerized three-dimensional medical image processing platform and the stereotactic particle implantation planning system (TPS) using the internationally advanced MonteCarlo Method of radiation dose field. The use of “particle knife” for tumor treatment refers to the implantation of miniature radioactive particles into tumors and tissues invaded by tumor infiltration under the guidance of TPS, including tumor lymphatic diffusion pathways, through the continuous low-energy gamma rays emitted by the particles, so that the tumor tissue suffers maximum destructive damage without damaging normal tissues. This can achieve the purpose of tumor treatment. The commonly used radioactive particles are 125I and 103Pa. 125I, in particular, has a rapid development in clinical application, with a half-life of 60.2 days, a radiation energy of 27-35 Kev, a tissue penetration of 1.7 cm, a dose rate of 0.05-0.10 Gy/H, and a specification of 0.5mm×4.8mm. The choice of radioactive particles depends on the type of tumor to be treated, the availability of radioactive particles, and the doctor’s preference for tumor treatment. The choice of radioactive particles depends on the type of tumor to be treated, the availability of radioactive particles and the doctor’s knowledge of their characteristics.
The main indications for which the “particle knife” is most suitable for treatment
Malignant tumor is still the primary factor of death in China, and there are more patients with advanced stage at the time of consultation, which reduces the chance of surgical treatment; tumor infiltration and invasion of important organs often affect the resection of tumor; the most fear is “metastatic cancer”, which is the appearance of cancer. Metastatic cancer” is the arrival of late stage of cancer, and it is extremely difficult to treat when there are more than two metastases in one organ.
With the application of “particle knife”, the particles are implanted into the body, which helps to kill the tumor as a whole without reducing the physiological function of the organs, reducing the tissue creation and treatment complications, and improving the survival rate of patients.
1.Treatment of various primary tumors and various metastatic tumors.
Lung cancer, mediastinoma, pleural mesothelioma, breast cancer, thyroid cancer, esophageal cancer, stomach cancer, rectal cancer, colon cancer, pancreatic cancer, bile duct cancer, liver cancer, nasopharynx, intraorbital tumor, tongue cancer, fundus of the mouth cancer, buccal mucosa cancer, prostate cancer, gynecological tumor, soft tissue tumor, brain glioma, brain metastasis tumor, meningioma, bone tumor
2.Tumors that patients are unwilling to undergo surgical resection.
3.Tumors that cannot be completely removed because of tumor infiltration of important organs.
4.Tumor patients who are not willing to undergo external irradiation or chemotherapy.
5.For the prevention of local recurrence or spread of tumor, prophylactic implantation is carried out.
The most terrible disease in today’s world is tumor. Although cancer is a persistent disease, it is not an incurable disease. Don’t rush to the doctor and blindly listen to some false or exaggerated information, the disease will not be cured and the person will be empty. Cancer patients should face the reality, do not despair, build up confidence, maintain a normal state of mind, respect science and believe that scientific treatment methods and new scientific technology can achieve the purpose of controlling and killing cancer cells, and they will be able to work and live like normal people.
Advantages of “particle knife” in treating various tumors
In the eyes of many people, particle knife is only an auxiliary way to treat tumors. In fact, it can not only be used as the main treatment for tumors, but also as the preferred treatment for some tumors. For some tumors that are not sensitive to conventional radiotherapy and chemotherapy, particle knife is actually an important treatment measure, such as prostate cancer, which was commonly treated with a combination of surgical resection, radiotherapy and chemotherapy in the past, and its effect was not satisfactory. Nowadays, it is possible to implant iodine 125 particles directly without surgery to inhibit tumor growth and achieve the same or better effect of conventional treatment, and retain its physiological function. In addition, for patients who are unwilling to undergo radical surgery and some inoperable cervical cancer and nasopharyngeal cancer, particle knife treatment is also a good choice. In addition, for patients with metastases, particle knife treatment can effectively control the growth of metastases, maintain the function of organs and reduce pain; for tumors that cannot be removed by surgery due to physical condition, tumor location and other factors, particle knife treatment can also be used. Specific treatment advantages are reflected in the following aspects.
Complementary effect with surgery: the addition of implanted radioactive particles in surgery is the most commonly used route among treatment methods, and the greatest effect played is the killing of the tumor as a whole.
Improving the completeness of tumor cure: when tumor invades adjacent important organs, even if the tumor can be removed, it is only a kind of palliative surgery with poor prognosis. Intraoperative addition of radioactive particle implantation, which distributes the source on lymphatic channels, residual tumor tissues and tumor bordering areas, is expected to obtain complete cure effect.
Reduced surgical trauma, shortened operative time and postoperative complications.
Intraoperative implantation of radioactive particles by puncture technique causes minimal trauma to normal tissues, eliminating the need to fully reveal the surgical field and avoiding blind extensive fat-clearing operations, which can reduce surgical trauma and interference with normal tissues to a greater extent, and smooth postoperative recovery of patients.
Complementary effect with chemotherapy.
The effect of preserving the function and morphology of the body.
The advantages of particle knife compared with traditional external radiotherapy are.
1.Although the external radiotherapy equipment is progressing rapidly, the treatment of intrathoracic malignant tumor which is moved up and down by breathing still has the defect of uneven radiation dose, and the intensity of its radiation source is too large, which causes more obvious complications to the patient’s organism; while the particles of particle knife are directly planted in the tumor, the radiation dose is uniform and not affected by the activity, and it rarely damages the normal tissues.
2.External radiotherapy cannot avoid the shortcomings of short-time fractionation. External radiotherapy can only treat the cells in a part of the tumor reproduction cycle. After the end of irradiation, the cells in other time phases can still recover their reproductive ability soon. Tumor cells can be stimulated to change from quiescent to active phase by any stimulation, and the cell multiplication time is significantly shortened, so they can still grow rapidly in the interval between irradiation sessions, which directly affects the therapeutic effect of external radiotherapy. In contrast, the particles of particle knife can irradiate tumor cells in the tumor for up to 180 days, until all tumor cells are killed.
3. When particle knife brachytherapy, the radioresistance of the spent cells decreases, while the reoxygenation of the spent cells decreases under the condition of continuous low-dose irradiation.
There are three ways of particle implantation for Particle Knife treatment.
1, template implantation.
2.B ultrasound and CT guided implantation.
3, intraoperative implantation.
Since particle implantation is performed in three dimensions and the physical characteristics of each radioactive particle are different, each nuclide requires a special three-dimensional treatment calculation system. Based on the images of lesions obtained from ultrasound and CT scans, the spatial distribution of simulated particle implantation is performed to determine the number of particle implants, the dose distribution in the target area and surrounding dangerous organs, and to guide clinical particle implantation.
After particle treatment, due to human activities and relative movement of organs, it is necessary to verify the quality of particle implantation by plain film or CT scan, and analyze whether the spatial distribution of implanted particles matches the treatment plan before implantation, whether there is any variation in dose distribution and whether the implanted particles are displaced.
Based on Monte Carlo principles, the radioactive particle implantation treatment plan is completed by computer image reconstruction of.
1.Ensure that the tumor treatment area is in the hot zone of dose field and the normal tissues, especially the sensitive organs, are in the cold zone through the optimal arrangement of particles.
2.Accurately calculate the dose field distribution of tumor tissues, normal tissues and sensitive tissues.
3.With the function of three-dimensional display of the formulated equal dose surface.
Prospect of particle knife for tumor treatment
With the successful development of new radionuclides such as 103Pd and the application of B-ultrasound and CT three-dimensional treatment planning system, particle therapy is more precisely positioned and the dose distribution is more uniform and reasonable. For those tumors that recur after surgery, especially after surgery and radiotherapy, particle implantation therapy is undoubtedly a more reasonable and effective treatment route.
However, there are still many clinical issues that need to be addressed.
1. such as how to select different radionuclides for tumors with different proliferation rates in order to obtain the maximum killing effect.
2. the rational combination of particle implantation therapy and external radiotherapy.
3. The prospect of clinical application of new radionuclides such as 241Am and 152Cf needs to be further clarified.
In conclusion, due to the characteristics of small trauma, uniform dose distribution in the target area and small damage to the surrounding normal tissues, the clinical application of particle implantation therapy for tumors shows a broad prospect.