The heavy ions with high linear energy transfer and high relative biological effectiveness are much more deleterious on the male germ cells, ones of the most radiosensitive cells of the body,than low-LET ionizing radi...The heavy ions with high linear energy transfer and high relative biological effectiveness are much more deleterious on the male germ cells, ones of the most radiosensitive cells of the body,than low-LET ionizing radiation such as X-ray or gamma-ray. The effects of low-dose heavy ion irradiation on male germ cell adaptation and genetics and the possible mechanism of this adaptation are summarized in our laboratory. Our results showed that the heavy ion irradiation significantly increased the frequencies of chromosomal aberrations in spermatogonia and spermato-cytes of mice, the low dose heavy ion irradiation could induce significant adaptative response on mouse testes and human sperm, and pre-exposure of mouse testes with low-dose heavy ion can markedly alleviate damage effects in-duced by subsequent high-dose irradiation. The increase of SOD activity and decrease of lipid peroxidation levels induced by low-dose ionizing radiation may be involved in this adaptative response mechanism. These studies may provide useful theoretical and clinical bases for radioprotection of reproductive potential and assessment of genetic risks for human exposed to heavy ions in radiotherapy and in outer space environment.展开更多
The influences of total ionizing dose （TID） on the single event effect （SEE） sensitivity of 34-nm and 25-nm NAND flash memories are investigated in this paper. The increase in the cross section of heavy-ion single...The influences of total ionizing dose （TID） on the single event effect （SEE） sensitivity of 34-nm and 25-nm NAND flash memories are investigated in this paper. The increase in the cross section of heavy-ion single event upset （SEU） in memories that have ever been exposed to TID is observed, which is attributed to the combination of the threshold voltage shifts induced by 7-rays and heavy ions. Retention errors in floating gate （FG） cells after heavy ion irradiation are observed. Moreover, the cross section of retention error increases if the memory has ever been exposed to TID. This effect is more evident at a low linear energy transfer （LET） value. The underlying mechanism is identified as the combination of the defects induced by 7-rays and heavy ions, which increases the possibility to constitute a multi-trap assisted tunneling （m- TAT） path across the tunnel oxide.展开更多
The clinical trials of tumor therapy using heavy ions beam 12C are now in progress at Institute of Modern Physics in Lanzhou. In order to achieve the precise radiotherapy with the high energy 12C beam in active pencil...The clinical trials of tumor therapy using heavy ions beam 12C are now in progress at Institute of Modern Physics in Lanzhou. In order to achieve the precise radiotherapy with the high energy 12C beam in active pencil beam scanning mode, we have developed an ionization chamber(IC) as an online monitor for beam intensity and also a dosimeter after calibration. Through the choosing of working gas and voltage, optimizing of the electrics and the read-out system, calibrating the linearity, the detector system provide us one of the simple and highly reliable way to monitoring the beam during the active pencil beam scanning treatments. The measurement results of this detector system show that it could work well under the condition of high energy 12C beam in active pencil beam scanning mode.展开更多
Fluence rates and angular distributions of the neutron emitted by75 MeV/u 12C-ion bombardment on thick Be and An targets have been measured bymeans of the threshold detector activation method. Based on that, the neutr...Fluence rates and angular distributions of the neutron emitted by75 MeV/u 12C-ion bombardment on thick Be and An targets have been measured bymeans of the threshold detector activation method. Based on that, the neutron yields,emission rates in the forward direction and neutron dose equivalent rate distributionswere deduced.展开更多
Up to now, clinical trials of heavy-ion radiotherapy for superficially placed tumors have been carried out for six times and over 60 selected patients have been treated with 80--100 MeV/u carbon ions supplied by the H...Up to now, clinical trials of heavy-ion radiotherapy for superficially placed tumors have been carried out for six times and over 60 selected patients have been treated with 80--100 MeV/u carbon ions supplied by the Heavy Ion Research Facility in Lanzhou （HIRFL） at the Institute of Modern Physics, Chinese Academy of Sciences since November, 2006. A passive irradiation system and a dose optimization method for radiotherapy with carbon-ion beams have been developed. Experimental verification of longitudinally therapeutic dose distributions was conducted under the condition of simulating patient treatment in the therapy terminal at HIRFL. The measured depth-dose distributions basically coincide with the expected ones. These results indicate that the irradiation system and the dose optimization method are effective in the ongoing carbon-ion radiotherapy for shallow-seated tumors at HIRFL.展开更多
Based on the characteristics of the interactions between intermediate energy heavy-ion beam and target matter, a method to calculate the depth-dose distribution of heavy-ion beams with intermediate energy (10-100 MeV/...Based on the characteristics of the interactions between intermediate energy heavy-ion beam and target matter, a method to calculate the depth-dose distribution of heavy-ion beams with intermediate energy (10-100 MeV/u) is presented. By comparing high energy beams where projectile fragmentation is overwhelming with low energies where energy straggling is the sole factor instead, a crescent energy spread with increasing depth and a simple fragmentation assumption were included for the depth-dose calculation of the intermediate energy beam. Relative depth-dose curves of carbon and oxygen ion beams with intermediate energies were computed according to the method here. Comparisons between the calculated relative doses and measurements are shown. The calculated Bragg curves, especially the upstream and downstream Bragg peaks, agree with the measured data. Differences between the two results appear only around the peak regions because of the limitations of the calculation and experimental conditions, but the展开更多
文摘The heavy ions with high linear energy transfer and high relative biological effectiveness are much more deleterious on the male germ cells, ones of the most radiosensitive cells of the body,than low-LET ionizing radiation such as X-ray or gamma-ray. The effects of low-dose heavy ion irradiation on male germ cell adaptation and genetics and the possible mechanism of this adaptation are summarized in our laboratory. Our results showed that the heavy ion irradiation significantly increased the frequencies of chromosomal aberrations in spermatogonia and spermato-cytes of mice, the low dose heavy ion irradiation could induce significant adaptative response on mouse testes and human sperm, and pre-exposure of mouse testes with low-dose heavy ion can markedly alleviate damage effects in-duced by subsequent high-dose irradiation. The increase of SOD activity and decrease of lipid peroxidation levels induced by low-dose ionizing radiation may be involved in this adaptative response mechanism. These studies may provide useful theoretical and clinical bases for radioprotection of reproductive potential and assessment of genetic risks for human exposed to heavy ions in radiotherapy and in outer space environment.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11690041,11675233,U1532261,and 11505243)
文摘The influences of total ionizing dose （TID） on the single event effect （SEE） sensitivity of 34-nm and 25-nm NAND flash memories are investigated in this paper. The increase in the cross section of heavy-ion single event upset （SEU） in memories that have ever been exposed to TID is observed, which is attributed to the combination of the threshold voltage shifts induced by 7-rays and heavy ions. Retention errors in floating gate （FG） cells after heavy ion irradiation are observed. Moreover, the cross section of retention error increases if the memory has ever been exposed to TID. This effect is more evident at a low linear energy transfer （LET） value. The underlying mechanism is identified as the combination of the defects induced by 7-rays and heavy ions, which increases the possibility to constitute a multi-trap assisted tunneling （m- TAT） path across the tunnel oxide.
基金Supported by the National Nature Science Foundation of China (No. 10305015, No.10475098)the Major Program of the Chinese Academy of Science (No. O701050YZD)
文摘The clinical trials of tumor therapy using heavy ions beam 12C are now in progress at Institute of Modern Physics in Lanzhou. In order to achieve the precise radiotherapy with the high energy 12C beam in active pencil beam scanning mode, we have developed an ionization chamber(IC) as an online monitor for beam intensity and also a dosimeter after calibration. Through the choosing of working gas and voltage, optimizing of the electrics and the read-out system, calibrating the linearity, the detector system provide us one of the simple and highly reliable way to monitoring the beam during the active pencil beam scanning treatments. The measurement results of this detector system show that it could work well under the condition of high energy 12C beam in active pencil beam scanning mode.
文摘Fluence rates and angular distributions of the neutron emitted by75 MeV/u 12C-ion bombardment on thick Be and An targets have been measured bymeans of the threshold detector activation method. Based on that, the neutron yields,emission rates in the forward direction and neutron dose equivalent rate distributionswere deduced.
基金Supported by Century Program of Chinese Academy of Science (O506120BR0)National High Technology Research and Development Program of China (863 Program, 2006AA02Z499)
文摘Up to now, clinical trials of heavy-ion radiotherapy for superficially placed tumors have been carried out for six times and over 60 selected patients have been treated with 80--100 MeV/u carbon ions supplied by the Heavy Ion Research Facility in Lanzhou （HIRFL） at the Institute of Modern Physics, Chinese Academy of Sciences since November, 2006. A passive irradiation system and a dose optimization method for radiotherapy with carbon-ion beams have been developed. Experimental verification of longitudinally therapeutic dose distributions was conducted under the condition of simulating patient treatment in the therapy terminal at HIRFL. The measured depth-dose distributions basically coincide with the expected ones. These results indicate that the irradiation system and the dose optimization method are effective in the ongoing carbon-ion radiotherapy for shallow-seated tumors at HIRFL.
基金This work was jointly supported by the Western Hope Project of the Chinese Academy of Sciences (Grant No. XB010612) the Director Foundation of the Institute of Modern Physics, the Chinese Academy of Sciences (Grant No. ZY010606).
文摘Based on the characteristics of the interactions between intermediate energy heavy-ion beam and target matter, a method to calculate the depth-dose distribution of heavy-ion beams with intermediate energy (10-100 MeV/u) is presented. By comparing high energy beams where projectile fragmentation is overwhelming with low energies where energy straggling is the sole factor instead, a crescent energy spread with increasing depth and a simple fragmentation assumption were included for the depth-dose calculation of the intermediate energy beam. Relative depth-dose curves of carbon and oxygen ion beams with intermediate energies were computed according to the method here. Comparisons between the calculated relative doses and measurements are shown. The calculated Bragg curves, especially the upstream and downstream Bragg peaks, agree with the measured data. Differences between the two results appear only around the peak regions because of the limitations of the calculation and experimental conditions, but the
