Release date: 2017-10-20
On October 14, 2017, the 3rd International Science and Technology Particle Forum was held at the Beijing Jiuhua International Conference Center.
Professor of the Clinical Technology Committee of Shanghai Proton Heavy Ion Hospital, Vice Chairman of the China Anti-Cancer Association, and Professor Jiang Guoliang, Academician of the American College of Radiology, gave an academic report titled "Three Years of Clinical Practice of Shanghai Proton and Heavy Ion Hospital".
Professor Jiang Guoliang has long been committed to the precise radiotherapy of tumors, especially the clinical and research of hepatobiliary and pancreatic tumors, as well as the research and development of multi-disciplinary treatment of proton heavy ion technology.
Professor Jiang Guoliang emphasized the biological effects of heavy ions (carbon ions) with obvious advantages over photons and protons during radiotherapy, and has a more effective killing effect in the treatment of tumors against radiotherapy.
Speaking points (Part 1)
Organized according to the information provided by the site and the organizer, without review by speakers
Currently, I am more interested in heavy ions (carbon ions). The benefits of protons, the benefits of physical doses, are much more and are not repeated.
There is a deficiency in heavy ion irradiation. Heavy ions have a small "tail" after the Bragg peak, and the dose after the "tail" is high; in addition, the biological dose of heavy ion irradiation is larger than that of protons.
Carbon ions have their benefits. The carbon ion ray half field is relatively small. When the carbon ion half field diameter is 5CM, the proton and carbon ion resolution are similar; but when the half field reaches 15CM, the edge of the carbon ion is still sharp, and the protons at this time follow the half field. The deeper the direction, the more the edge of the radiation field becomes blurred.
What are the benefits of sharp edges? As the edge of the field becomes sharp, the carbon ion half field is relatively small. In patients with liver tumors, the dose of carbon ions (15.49 ± 2.62 $) to normal liver is lower than that of protons ( 17.00 ± 2.92 #). Carbon ion radiotherapy liver cancer protects the liver better.
The dose of carbon ions to normal organs is lower than that of protons, but the normal organ dose in the deep part of the Bragg peak is increased.
For example, the skull base tumor is close to the brain stem, carbon ions can reduce the dose of the brain stem, and the brain stem is better protected.
For example, liver cancer is close to the stomach, even close to the stomach, duodenum or colon. In this case, the treatment plan should be carefully selected to avoid damage to the digestive tract, and carbon ions can reduce the dose to the stomach.
Protons are low LET rays, and radiation damage is a single-strand break in DNA, with sublethal and potential radiation damage repair.
Carbon ions are high LET rays, and in the damage of the Bragg peak, 70% are DNA double-strand breaks, and double-strand breaks are difficult to repair.
If the photon effect of photon (X-ray) radiotherapy is 1, the radiobiological effect of protons is 1.1-1.2 times that of photon (X-ray) radiotherapy; the radiobiology of carbon ion line is the photon (X-ray) radiotherapy biological effect. 2-3 times.
This is also a double-edged sword. If carbon ions are irradiated to normal tissues, the damage of normal tissues is also serious, which requires very precise illumination of carbon ions.
Carbon ions have a stronger radiobiological damage effect (tumor and normal tissue) and anti-radiation tumors have a more effective killing effect (tumor specificity), for example, a stronger killing effect on hypoxic cells.
Hypoxic cells are resistant to radiation, and it is very difficult to kill hypoxic cells. When irradiated with carbon ions, the oxygen gain of hypoxic cells (ie, more effective killing of hypoxic tumor cells) is reduced to 2 or even lower, and with protons or photons, the oxygen gain ratio is still 3.
At the same time, carbon ions have a stronger biological effect on carbon ions for inherent anti-radiation tumor cells such as melanoma, osteosarcoma, chondrosarcoma, chordoma, soft tissue sarcoma, and tumor stem cells.
Where does the stronger biological effect of heavy ions occur?
The strong biological effect is not found in the entire ray path. In the peak region where the heavy ions advance (Bragg peak region), the radiobiological effect of carbon ions is slightly higher than that of protons; the closer to the peak region, the radioactive organisms of carbon ions The stronger the effect.
Before reaching the peak area, the radiobiological effect of carbon ions is 1.5-1.6, which is not very serious to the normal group in front of the tumor; the carbon ion ray is 2-3 times relative to the biological effect to the peak region. Relatively speaking, carbon ion rays are well suited for radiation therapy.
Doctor Profile: Jiang Guoliang, Chief Physician, Professor, Doctoral Supervisor, Director of Clinical Technology Committee of Shanghai Proton Heavy Ion Hospital, Vice Chairman of China Anti-Cancer Association, Honorary Fellow of American College of Radiology. He has served as the director and dean of the radiotherapy department of the Cancer Hospital of Fudan University.
Source: CPTN heavy ion proton (micro signal zhonglizizhizi)
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