Heavy ion cancer treatment two advantages
Authors: Chuan-Ling Guo, Ju-Fang Wang, Xiao-
Dong Jin, Wei Wei, Li Jian
【Abstract】 Objective To observe the two kinds of human cancer cells human hepatoma cells SMMC 7721, and A375
human melanoma cells of high LET12C6 ions and γ-ray
irradiation sensitivity and sub-sub-effect, observed heavy ion
treatment of tumors and the feasibility of advantage. Method to two kinds of in vitro culture of different organizations from the body with a high radiation resistance of malignant cells in the experimental object, respectively 12C6 and γ-ray
doses of 0 ~ 6Gy different points of single and fractionated irradiation, using clone survival France statistics cell survival fraction. The results, whether single or fractionated irradiation, 12C6 cell survival after irradiation two kinds of scores were significantly lower than the γ-ray irradiation of
cells, but also the sub-sub-effect of heavy ions is markedly
lower. Conclusion The results showed that heavy ions in cancer therapy are two important advantages, namely, tumors with high and low sub-sub-lethal effects, indicating heavy ion
irradiation-induced low-repair phenomenon, allows more
efficient tumor radiotherapy.
Key words tumor cells; heavy ion; survival fraction
Key words: Tumor cells; Heavy ions; Survival fractions
Radiation therapy is an important means to treat malignant tumors. Conventional radiation therapy used in γ,
X-ray and electron beam into the human body resulting from the increase of dose with depth exponential decay of tumors and normal tissues have some before and after in vitro. As the
dose distribution of heavy-ion Bragg peak, enabling high-
absorbed dose, are concentrated in the tumor site, thereby effectively protecting the surrounding healthy tissue, and has
a high relative biological effectiveness, repair, and low efficiency in the radiation therapy on the ideal. 70 mid-20th
century, the United States, Lawrence Berkeley Laboratory will first used in clinical heavy ion therapy, achieved remarkable
results, Japan and Germany in the 90's have also started a heavy ion cancer, the current part of the local control rate of tumor has reached 100% . Since 1995, China will be "nuclear medicine and radiation therapy in advanced technology research" as the State Science and Technology Commission, "95" Climbing Program (B) project, which the "Heavy Ion Cancer technology" is an important research content of the 1. After nearly a decade of effort, at present, the Institute of Modern Physics, Lanzhou heavy ion accelerator to treat cancer have started up, treatment, basically completed the terminal building, our country most likely to achieve at the end of 2005, heavy ions a major breakthrough in the treatment of cancer.
With the purpose of conducting basic research, this study intends to use the Lanzhou Heavy Ion Accelerator (HIRFL) provided by the 12C6 ion beam (LET = 96.05keV/μm) and Lanzhou
University, Department of Radiology, First Affiliated Hospital of 60Co γ-ray source generated by respectively two different
tissue-derived human tumor cells in single and fractionated irradiation, observed two kinds of irradiation on different tumor cell-killing effect and sub-sub-effect, observed heavy
ion treatment of tumors in the feasibility and advantages.
1 Materials and methods
1.1 Cells and culture experiments used in human hepatoma SMMC 7721 cells, human melanoma A375 cells were purchased from Beijing 301 Hospital, culture medium containing 10% fetal calf serum Class Standard (Lanzhou, China marine organisms) in
RPMI 1640 (GIBCO) culture medium, placed in 5% CO2 37 ?
incubator. According to the pre-draw the growth curve
experiments, cells 20h after the passage in the logarithmic growth phase, select the cells were irradiated at this time.
1.2 irradiation (1) γ-ray irradiation: The First
Affiliated Hospital of Lanzhou Medical College, Department of
Radiology sources of 60Co γ-ray irradiation. A total of
single 0,0.5,1,1.5,2,3,4 Gy irradiation dose of 7 points, fractionated irradiation on the corresponding set (0 0) Gy, (0.5 0.5) Gy, (1 1) Gy, (1.5 1.5) Gy, (2 2) Gy dose of 5 points, fractionated irradiation time interval set to 6h. Each dose point with three parallel samples. (2) heavy ion irradiation: The Institute of Modern Physics, Lanzhou HIRFL
provided 12C6 ion beam (LET = 96.05KeV/μm) for heavy ion
irradiation. Dose point and sub-sub-time with the same γ-ray
1.3 after irradiation treatment of cells after irradiation by trypsin digestion the cell an exact count.
Select the appropriate dilution of diluted viable cells to about 100 / plate concentration grown in culture dishes, were placed on carbon dioxide incubator at 37 ? 9d. Giemsa
staining method, statistical cell count is greater than 50 the number of clones. Reposted elsewhere in the paper for free download http://
1.4 the experimental data to obtain cell survival fraction (survival fraction, SF) according to the following formula:
SF (%)=( Sx/S0) × 100%
Where Sx on behalf of the exposed cell clone formation
rate, S0 on behalf of the control cell colony formation rate. The final value of SF obtained three sets of parallel samples of the average ? SD (standard diviation). Draw cells were single and fractionated irradiation dose - survival curve, a
linear square-fitting model.
2.1 single and fractionated irradiation, heavy ions on two kinds of tumor cell killing effects were significantly higher than the γ-ray
2.2 Heavy ion irradiation was significantly lower than the sub-sub-effect of γ-ray
In the experiment, we use a curve in the Bragg peak region LET for 96.05KeV/μm of 12C6 + ion beam. From Figure 1 to 4 can be seen, whether it is single or fractionated irradiation, 12C6 + irradiated two kinds of cell survival fraction were significantly lower than the γ-ray irradiation
of cells, demonstrating heavy ions and γ-rays, compared with
a markedly improved of anti-tumor capacity. Conventional low-
LET radiation (eg X, γ-ray and linear electron accelerator
bremsstrahlung) energy in the organization was a gradual
increase in attenuation, or start with a small amplitude and then decay trend. When the charged heavy ions through the substance, in the interaction with the material through its depth dose curve expression in the early stages of the
absorbed dose range is relatively constant, showing a stable floor area, and in the end of the range, ion the speed becomes very low, its energy loss rate increased dramatically, creating a high ionization density Bragg peak, peak area and Ping An ion of LET was markedly different. Ping Area LET
basically the same as X-rays, while the Peak District is much higher than the X-rays, heavy ions, this feature make it in cancer therapy has a special advantage. Conventional therapy in killing cancer cells, while the surrounding healthy tissue
is also subject to greater damage, resulting in significant side effects, and even some complications. Although radiotherapy equipment is very tight design (for example: γ
knife, neutron knife, etc.), but the carcinoma surrounding
normal tissues and organs continue to be relatively high doses of radiation. In order to avoid the tumor surrounding normal tissue (especially for the important radiation-sensitive
tissues and organs) are unnecessary damage, and sometimes had to reduce the total dose, rendering the tumor volume without the necessary exposure dose; in heavy-ion treatment, if the
tumor placed in Bragg Peak District and the normal tissues in the floor area in the irradiation can make normal tissue and tumor respectively, in the low LET and high LET Division, when the tumor and normal tissues of the exposed significantly different energy , but due to high LET heavy ion irradiation of anti-tumor cells relative biological effect (RBE) was significantly higher than conventional radiation, so select
the appropriate dose of the incident can maximize anti-tumor
cells while protecting normal tissue .
Be seen from Figure 5 to 8, two kinds of cells, heavy ion irradiation effects of both the lower graded. From the cell
level analysis, sub-lethal damage (sublethal damage) is a
mammal is an important type of radiation damage, when only a portion of the key intracellular target ionization events occur, if given sufficient time, the cells may repair the damage of these . Because of the existence of such a
repair, fractionated irradiation on cell survival rate of more than a single irradiation markedly improved . The degree of sublethal damage repair and survival curve shoulder width of the good correlation between, this is because both are the
same basic phenomenon (sub-lethal damage repair cumulative)
performance . The results show that two kinds of tumor cells by low LET (γ rays) irradiation, Jun Cheng with a
"shoulder" area of the dose-survival curves show that both
cells have a strong ability to repair it with the clinical manifestations of the radiotherapy the same high degree of resistance. The heavy ion irradiation by the dose-survival
curve shoulder area no longer exists significant, indicating heavy ion irradiation led to two kinds of cells in a limited
sub-lethal damage repair, showing effects of low-graded. This
may be because the adoption of the cell, ionizing heavy ion track more complex, causing cell damage is also more complex and difficult to repair. Clinical generally taken several
times to make the surrounding normal tissue irradiation is effectively restored, but the tumor cells in the fractionated irradiation also can be restored, so fractionated irradiation significantly reduced the efficiency of radiation treatment.
In the heavy ion treatment of cancer, due to significantly lower cell repair can take less exposure times to achieve the purpose of anti-tumor, thereby greatly improving the
efficiency of cancer treatment to alleviate pain.
In recent years, international response to heavy ion beam cancer research and clinical application of increasing temperature and speed in the world where there are heavy ion accelerator of the country, without exception, carried out this work. This proves that uses heavy ion beams to conduct
clinical cancer recognized as a science-based, and therefore
has become a cutting-edge research in this area hot spots. Our experiments for domestic heavy-ion beam to provide an
effective foundation for cancer research data and theoretical
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