In the past decade carbon ion beam has attracted growing interest in cancer therapy. This could be attributed to the excellent characteristics of the carbon ion beam in physical and biological selectivities such as do...In the past decade carbon ion beam has attracted growing interest in cancer therapy. This could be attributed to the excellent characteristics of the carbon ion beam in physical and biological selectivities such as dose localization in the Bragg peak and high relative biological effectiveness over the peak. To enhance the efficacy of heavy ion beams in treating tumors, we have even proposed a novel idea usingβ-delayed particle decay beams such as 9C, 8B and 8Li. These ra'dioactive ion beams (RIB) isotropically emit low展开更多
An enhanced cell-killing effect at the penetration depths around the Bragg peak of a β-delayed particle decay 9C -ion beam has been observed in our preceding radiobiological experiments in comparison with a therapeut...An enhanced cell-killing effect at the penetration depths around the Bragg peak of a β-delayed particle decay 9C -ion beam has been observed in our preceding radiobiological experiments in comparison with a therapeutic 12C beam under the same conditions, and RBE values of the 9C beam were revealed to be higher than those of the comparative 12C beam by a factor of up to 2. This study was aimed at investigating the biophysical mechanisms underlying the important experimental phenomenon.展开更多
A β-delayed particle decay beam like 9C has been recognized as a double irradiation source, i.e. the external beam radiation itself and the delayed low-energy particles emitted internally. A radioactive 9C-ion beam, ...A β-delayed particle decay beam like 9C has been recognized as a double irradiation source, i.e. the external beam radiation itself and the delayed low-energy particles emitted internally. A radioactive 9C-ion beam, therefore, is considered to be very useful in cancer radiation therapy. To explore the potential importance of radioactive 9C-ion beams in cancer therapy, radiobiological experiments using a 9C beam supplied by the secondary beam line (SBL) at the Heavy Ion Medical Accelerator in Chiba (HIMAC), Japan were carried out.展开更多
An enhanced cell-killing effect at the penetra- tion depths around the Bragg peak of a β-delayed particle decay 9C-ion beam has been observed in our preceding ra- diobiological experiments in comparison with a therap...An enhanced cell-killing effect at the penetra- tion depths around the Bragg peak of a β-delayed particle decay 9C-ion beam has been observed in our preceding ra- diobiological experiments in comparison with a therapeutic 12C beam under the same conditions, and RBE values of the 9C beam were revealed to be higher than those of the comparative 12C beam by a factor of up to 2. This study is aimed at investigating the biophysical mechanisms underlying the important experimental phenomenon. First of all, a model for calculating the stopping probability density of the experimentally applied 9C beam is worked out, where all determinants such as the initial momentum spread of the 9C beam, the fluence attenuation with penetration depth due to the projectile-target nuclear reaction and the energy strag- gling effect are taken into account. On the basis of the calcu- lated 9C-ion stopping distribution, it has been found that the area corresponding to the enhanced cell-killing effect of the 9C beam appears at the stopping region of the incident 9C ions. The stopping 9C-ion density in depth, then, is derived from the calculated probability density. Moreover, taking entrance dose 1 Gy for the 9C beam as an example, the aver- age stopping 9C-ion numbers per cell at various depths are deduced. Meanwhile, the mean lethal damage events induced by the 9C and comparative 12C beams at the depths with al- most equal dose-averaged LETs are derived from the meas- ured cell surviving fractions at these depths for the 9C and 12C beams. Under the condition of the same absorbed doses, there are indeed good agreements between the average stop- ping 9C-ion number pre cell and the difference of the mean lethal damage events between the 9C and 12C beams at the depths of similar dose-averaged LETs. It can be inferred that if a 9C ion comes to rest in a cell, the cell would undergo dy- ing. In view of the decay property of 9C nuclide, clustered damage would be caused in the cell by the emitted low-energy particles. Therefore, the results achieved in this work can be taken as indirect evidence supporting that damage cluster is more efficient in leading to cell lethality.展开更多
Nuclear structure of proton-rich unstable nucleus 28P has been studied by measuring its g-factor for the first time. The g-factor of 28P (Iπ =3+, T1/2=270.3 ms) was measured by means of β-NMR technique combined with...Nuclear structure of proton-rich unstable nucleus 28P has been studied by measuring its g-factor for the first time. The g-factor of 28P (Iπ =3+, T1/2=270.3 ms) was measured by means of β-NMR technique combined with the new polarization technique for charge exchange reaction product in the intermediate energy heavy ion collisions. The obtained g-factor of g=0.1028(27) is very much quenched from the Schmidt value, but is well reproduced by the shell model (+0.102). In connection with the magnetic moment of the mirror partner and the β-ray transition probability, the orbital angular momenta and intrinsic spins of protons and neutrons have been determined as lp =0.43(29), ln =1.85(29), Sp)=0.28(4), and Sn =0.44(4).展开更多
文摘In the past decade carbon ion beam has attracted growing interest in cancer therapy. This could be attributed to the excellent characteristics of the carbon ion beam in physical and biological selectivities such as dose localization in the Bragg peak and high relative biological effectiveness over the peak. To enhance the efficacy of heavy ion beams in treating tumors, we have even proposed a novel idea usingβ-delayed particle decay beams such as 9C, 8B and 8Li. These ra'dioactive ion beams (RIB) isotropically emit low
文摘An enhanced cell-killing effect at the penetration depths around the Bragg peak of a β-delayed particle decay 9C -ion beam has been observed in our preceding radiobiological experiments in comparison with a therapeutic 12C beam under the same conditions, and RBE values of the 9C beam were revealed to be higher than those of the comparative 12C beam by a factor of up to 2. This study was aimed at investigating the biophysical mechanisms underlying the important experimental phenomenon.
文摘A β-delayed particle decay beam like 9C has been recognized as a double irradiation source, i.e. the external beam radiation itself and the delayed low-energy particles emitted internally. A radioactive 9C-ion beam, therefore, is considered to be very useful in cancer radiation therapy. To explore the potential importance of radioactive 9C-ion beams in cancer therapy, radiobiological experiments using a 9C beam supplied by the secondary beam line (SBL) at the Heavy Ion Medical Accelerator in Chiba (HIMAC), Japan were carried out.
基金supported by the Century Program of the Chinese Academy of Sciencesthe National Natural Science Foundation of China(Grant No.10205021)
文摘An enhanced cell-killing effect at the penetra- tion depths around the Bragg peak of a β-delayed particle decay 9C-ion beam has been observed in our preceding ra- diobiological experiments in comparison with a therapeutic 12C beam under the same conditions, and RBE values of the 9C beam were revealed to be higher than those of the comparative 12C beam by a factor of up to 2. This study is aimed at investigating the biophysical mechanisms underlying the important experimental phenomenon. First of all, a model for calculating the stopping probability density of the experimentally applied 9C beam is worked out, where all determinants such as the initial momentum spread of the 9C beam, the fluence attenuation with penetration depth due to the projectile-target nuclear reaction and the energy strag- gling effect are taken into account. On the basis of the calcu- lated 9C-ion stopping distribution, it has been found that the area corresponding to the enhanced cell-killing effect of the 9C beam appears at the stopping region of the incident 9C ions. The stopping 9C-ion density in depth, then, is derived from the calculated probability density. Moreover, taking entrance dose 1 Gy for the 9C beam as an example, the aver- age stopping 9C-ion numbers per cell at various depths are deduced. Meanwhile, the mean lethal damage events induced by the 9C and comparative 12C beams at the depths with al- most equal dose-averaged LETs are derived from the meas- ured cell surviving fractions at these depths for the 9C and 12C beams. Under the condition of the same absorbed doses, there are indeed good agreements between the average stop- ping 9C-ion number pre cell and the difference of the mean lethal damage events between the 9C and 12C beams at the depths of similar dose-averaged LETs. It can be inferred that if a 9C ion comes to rest in a cell, the cell would undergo dy- ing. In view of the decay property of 9C nuclide, clustered damage would be caused in the cell by the emitted low-energy particles. Therefore, the results achieved in this work can be taken as indirect evidence supporting that damage cluster is more efficient in leading to cell lethality.
基金Supported by National Natural Science Foundation of China (10435010, 10505032)
文摘Nuclear structure of proton-rich unstable nucleus 28P has been studied by measuring its g-factor for the first time. The g-factor of 28P (Iπ =3+, T1/2=270.3 ms) was measured by means of β-NMR technique combined with the new polarization technique for charge exchange reaction product in the intermediate energy heavy ion collisions. The obtained g-factor of g=0.1028(27) is very much quenched from the Schmidt value, but is well reproduced by the shell model (+0.102). In connection with the magnetic moment of the mirror partner and the β-ray transition probability, the orbital angular momenta and intrinsic spins of protons and neutrons have been determined as lp =0.43(29), ln =1.85(29), Sp)=0.28(4), and Sn =0.44(4).
