To investigate the effects of long-term low dose hormone replacement therapy （HRT） on postmenopaosal women in homone level, cognition score, hippocampus volume, and magnetic resonance spectroscopy （MRS） parameters...To investigate the effects of long-term low dose hormone replacement therapy （HRT） on postmenopaosal women in homone level, cognition score, hippocampus volume, and magnetic resonance spectroscopy （MRS） parameters. Methods A total of 182 postmenopausal women aged 50-87 years were chosen at Peking Union Medical College Hospital and assigned to HRT group and control group. The volunteers of HRT group had taken low dose hormone [ estradiol （E2 ） 0. 5-1.0 mg and progesterone 0.5-2.0 mg, once a day ] for 4-33 years. The concentrations of E2, progesterone, and testosterone were measured using enzyme-linked immunosorbent assay （ELISA）. The gene types of apolipoprotein E （ApoE） were measured by polymerase chain reaction, and the subjects with susceptible genes （ ApoE ε3/ε4） of Alzheimer＇s disease （AD） were screened. Their hippocampus volumes and MRS parameters were obtained through magnetic resonance imaging （MRI）, and results in two groups were analyzed by statistical method. Results Compared with control group, the concentrations of E2 at each age stage in HRT group were significantly higher （P 〈0. 05） except the 80-89 years old subgroup; yet, there were no statistical differences in the concentrations of progesterone and testosterone between the two groups. There was no obvious difference in ApoE subtypes distribution between the two groups The results of hippocampus MRI for the subjects with susceptible genes ApoE ε3/ε4 （HRT group 14 cases, control group 11 cases） showed that the ratio of bilateral hippocampus volume to whole brain volume in HRT group （0. 406 ± 0.028） was signiticantlyhigher than control gronp （0.369±0.031, P〈0.05）. Theresults of ^1H MRS for the subjects with susceptible genes ApoE ε3/ε4 （ HRT group 12 cases, control group 11 cases） showed that the N-acetylaspartate/total creatine at the area of hippocampus in HRT group （ 1.54±0. 08 ） were significantly higher than control group （ 1.45±0. 13, P 〈 0. 05）. Conclusions For postmenopausal women, long-term low dose HRT can maintain the physiological concentration of E2 in plasma. Furthermore, the hippocampus MRI performed on those with ApoE ε3/ε3 genes shows that long-term low dose HRT can prevent hippocampus atrophy, which is beneficial to maintain the brain function and prevent AD.展开更多
The mechanisms occurring when the switched temperature technique is applied,as an accelerated enhanced low dose rate sensitivity(ELDRS)test technique,are investigated in terms of a specially designed gate-controlled l...The mechanisms occurring when the switched temperature technique is applied,as an accelerated enhanced low dose rate sensitivity(ELDRS)test technique,are investigated in terms of a specially designed gate-controlled lateral PNP transistor(GLPNP)that used to extract the interface traps(Nit)and oxide trapped charges(Not).Electrical characteristics in GLPNP transistors induced by ^(60)Co gamma irradiation are measured in situ as a function of total dose,showing that generation of Nit in the oxide is the primary cause of base current variations for the GLPNP.Based on the analysis of the variations of Nit and Not,with switching the temperature,the properties of accelerated protons release and suppressed protons loss play critical roles in determining the increased Nit formation leading to the base current degradation with dose accumulation.Simultaneously the hydrogen cracking mechanisms responsible for additional protons release are related to the neutralization of Not extending enhanced Nit buildup.In this study the switched temperature irradiation has been employed to conservatively estimate the ELDRS of GLPNP,which provides us with a new insight into the test technique for ELDRS.展开更多
The low dose effects induced by carbon ions on Chinese hamster V79 cells and murine melanoma B16 cells were investigated in this paper. Both cell lines were divided into four groups for irradiation: (1) control, (2) 0...The low dose effects induced by carbon ions on Chinese hamster V79 cells and murine melanoma B16 cells were investigated in this paper. Both cell lines were divided into four groups for irradiation: (1) control, (2) 0.02 Gy or 0.05 Gy(D1), (3) 1 Gy(D2), (4) D1+D2. The survivors and micronuclei were studied as biological endpoints. The results of group (1) and group (2) showed that there were no obvious differences on micronucleus frequency but there were significant increases when irradiation dose was 0.02Gy on colony formation efficiency. Although low dose ion irradiation could not contribute to DNA damages, it could enhance the colony formation efficiency. In the study of group (3) and (4), when the ion dose was 0.02 Gy, there were evident increases on surviving fraction and decreases on micronucleus frequency, but there were no statistical changes on these endpoints when the ion dose was 0.05Gy. This meant that high LET radiation could induce the adaptive response of cultured cells, furthermore, in the range of inducing ion dose , low dose irradiation was more profitable than high dose one.展开更多
WT5”BZ] To study the molecular mechanism of the stimulatory effect of low dose radiation(LDR) on T cell activation. [WT5”BX]Methods.[WT5”BZ] Thymocytes from Kunming mice exposed to whole body irradiation(WBI) with ...WT5”BZ] To study the molecular mechanism of the stimulatory effect of low dose radiation(LDR) on T cell activation. [WT5”BX]Methods.[WT5”BZ] Thymocytes from Kunming mice exposed to whole body irradiation(WBI) with different doses of X rays were analyzed for the changes in signal molecules of the phospholipase C phosphatidylinositol biphosphate(PLC IP2) and G protein adenylate cyclase(AC) pathways. [WT5”BX]Results.[WT5”BZ]It was found that[Ca 2+ ] i increased in response to doses within 0 2 Gy which was most marked after 0 075 Gy and the increase was accentuated in the presence of Con A. The changes in CD3 and calcineurin(CN) expression of the thymocytes followed the same pattern as the alterations in [Ca 2+ ] i after LDR. The expression of α,β1 and β2 isoforms of protein kinase C(PKC) was all up regulated after 0 075 Gy with the increase in PKC β1 expression being most marked. The cAMP/cGMP ratio and PKA activity of the thymocytes was lowered after low dose radiation and increased after doses above 0 5 Gy in a dose dependent manner, thus giving rise to J shaped dose response curves. The Ca antagonist TMB 8 and cAMP stimulant cholera toxin suppressed the augmented thymocyte proliferation induced by LDR. [WT5”BX]Conclusion.[WT5”BZ]Data presented in the present paper suggest that activation of the PLC PIP2 signal pathway and suppression of the AC cAMP signal pathway are involved in the stimulation of the thymocytes following WBI with low dose X rays.展开更多
Because of the growing concern over the radiation dose delivered to patients, X-ray cone-beam CT(CBCT) imaging of low dose is of great interest. It is difficult for traditional reconstruction methods such as Feldkamp ...Because of the growing concern over the radiation dose delivered to patients, X-ray cone-beam CT(CBCT) imaging of low dose is of great interest. It is difficult for traditional reconstruction methods such as Feldkamp to reduce noise and keep resolution at low doses. A typical method to solve this problem is using optimizationbased methods with careful modeling of physics and additional constraints. However, it is computationally expensive and very time-consuming to reach an optimal solution. Recently, some pioneering work applying deep neural networks had some success in characterizing and removing artifacts from a low-dose data set. In this study,we incorporate imaging physics for a cone-beam CT into a residual convolutional neural network and propose a new end-to-end deep learning-based method for slice-wise reconstruction. By transferring 3D projection to a 2D problem with a noise reduction property, we can not only obtain reconstructions of high image quality, but also lower the computational complexity. The proposed network is composed of three serially connected sub-networks: a cone-to-fan transformation sub-network, a 2D analytical inversion sub-network, and an image refinement sub-network. This provides a comprehensive solution for end-to-end reconstruction for CBCT. The advantages of our method are that the network can simplify a 3D reconstruction problem to a 2D slice-wise reconstruction problem and can complete reconstruction in an end-to-end manner with the system matrix integrated into the network design. Furthermore, reconstruction can be less computationally expensive and easily parallelizable compared with iterative reconstruction methods.展开更多
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 radiation effects on several properties （reference voltage, digital output logic voltage, and supply current） of dual 8-bit analog-to-digital （A/D） converters （AD9058） under various biased conditions are inv...The radiation effects on several properties （reference voltage, digital output logic voltage, and supply current） of dual 8-bit analog-to-digital （A/D） converters （AD9058） under various biased conditions are investigated in this paper. Gamma ray and 10-MeV proton irradiation are selected for a detailed evaluation and comparison. Based on the measurement results induced by the gamma ray with various dose rates, the devices exhibit enhanced low dose rate sensitivity （ELDRS） under zero and working bias conditions. Meanwhile, it is obvious that the ELDRS is more severe under the working bias condition than under the zero bias condition. The degradation of AD9058 does not display obvious ELDRS during 10-MeV proton irradiation with the selected flux.展开更多
目的探讨低辐射剂量扫描联合深度学习重建(DLIR)算法在CT引导下肺穿刺活检中应用的可行性及临床价值。方法选取2023年9月~2024年3月在陕西中医药大学附属医院行CT引导下肺穿刺患者,根据扫描方案不同,将60例肺穿刺活检患者分为常规剂量...目的探讨低辐射剂量扫描联合深度学习重建(DLIR)算法在CT引导下肺穿刺活检中应用的可行性及临床价值。方法选取2023年9月~2024年3月在陕西中医药大学附属医院行CT引导下肺穿刺患者,根据扫描方案不同,将60例肺穿刺活检患者分为常规剂量组(A组)和低剂量组(B组)。A组为100 kV,噪声指数(NI)=15;B组NI=45,其余扫描参数均相同。在常规剂量组中首次和末次全肺扫描分别采用A、B组参数扫描,用于评价深度学习重建算法(DLIR)改善图像质量潜能。A组中首次全肺扫描采用滤波反投影(FBP)和权重为50%自适应统计迭代重建-V(50%ASIR-V)重建,末次全肺扫描采用深度学习重建算法的3种强度(DLIR-L、DLIR-M、DLIR-H)重建图像。分别测量脊柱旁肌肉、皮下脂肪及主动脉血管CT值和SD值,计算信号噪声比(SNR)和对比噪声比(CNR)。对比A、B两组的患者基线特征、穿刺过程中总的辐射剂量、病理阳性率及并发症发生率。结果5种不同条件下重建图像在肌肉、皮下脂肪及主动脉血管处CT值差异无统计学意义(P>0.05),SD值、SNR和CNR值差异有统计学意义(P<0.05),组间两两比较分析显示,DLIR-H图像与50%ASIR-V图像在肌肉、脂肪、血管SD和SNR的差异无统计学意义(P>0.05);FBP vs DLIR-H和DLIR-L vs DLIR-H组的CNR值差异有统计学意义(P<0.05)。与A组总辐射剂量相比,B组总辐射剂量减少约93.6%(P<0.001)。两组图像质量均能满足临床穿刺需要,两组患者的基线特征、病理阳性率及并发症发生率的差异均无统计学意义(P>0.05)。结论低剂量CT扫描结合DLIR重建,可以显著降低图像噪声,提高图像质量,且不影响穿刺安全性和病理阳性率。展开更多
文摘To investigate the effects of long-term low dose hormone replacement therapy （HRT） on postmenopaosal women in homone level, cognition score, hippocampus volume, and magnetic resonance spectroscopy （MRS） parameters. Methods A total of 182 postmenopausal women aged 50-87 years were chosen at Peking Union Medical College Hospital and assigned to HRT group and control group. The volunteers of HRT group had taken low dose hormone [ estradiol （E2 ） 0. 5-1.0 mg and progesterone 0.5-2.0 mg, once a day ] for 4-33 years. The concentrations of E2, progesterone, and testosterone were measured using enzyme-linked immunosorbent assay （ELISA）. The gene types of apolipoprotein E （ApoE） were measured by polymerase chain reaction, and the subjects with susceptible genes （ ApoE ε3/ε4） of Alzheimer＇s disease （AD） were screened. Their hippocampus volumes and MRS parameters were obtained through magnetic resonance imaging （MRI）, and results in two groups were analyzed by statistical method. Results Compared with control group, the concentrations of E2 at each age stage in HRT group were significantly higher （P 〈0. 05） except the 80-89 years old subgroup; yet, there were no statistical differences in the concentrations of progesterone and testosterone between the two groups. There was no obvious difference in ApoE subtypes distribution between the two groups The results of hippocampus MRI for the subjects with susceptible genes ApoE ε3/ε4 （HRT group 14 cases, control group 11 cases） showed that the ratio of bilateral hippocampus volume to whole brain volume in HRT group （0. 406 ± 0.028） was signiticantlyhigher than control gronp （0.369±0.031, P〈0.05）. Theresults of ^1H MRS for the subjects with susceptible genes ApoE ε3/ε4 （ HRT group 12 cases, control group 11 cases） showed that the N-acetylaspartate/total creatine at the area of hippocampus in HRT group （ 1.54±0. 08 ） were significantly higher than control group （ 1.45±0. 13, P 〈 0. 05）. Conclusions For postmenopausal women, long-term low dose HRT can maintain the physiological concentration of E2 in plasma. Furthermore, the hippocampus MRI performed on those with ApoE ε3/ε3 genes shows that long-term low dose HRT can prevent hippocampus atrophy, which is beneficial to maintain the brain function and prevent AD.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.U1532261 and 1630141)
文摘The mechanisms occurring when the switched temperature technique is applied,as an accelerated enhanced low dose rate sensitivity(ELDRS)test technique,are investigated in terms of a specially designed gate-controlled lateral PNP transistor(GLPNP)that used to extract the interface traps(Nit)and oxide trapped charges(Not).Electrical characteristics in GLPNP transistors induced by ^(60)Co gamma irradiation are measured in situ as a function of total dose,showing that generation of Nit in the oxide is the primary cause of base current variations for the GLPNP.Based on the analysis of the variations of Nit and Not,with switching the temperature,the properties of accelerated protons release and suppressed protons loss play critical roles in determining the increased Nit formation leading to the base current degradation with dose accumulation.Simultaneously the hydrogen cracking mechanisms responsible for additional protons release are related to the neutralization of Not extending enhanced Nit buildup.In this study the switched temperature irradiation has been employed to conservatively estimate the ELDRS of GLPNP,which provides us with a new insight into the test technique for ELDRS.
基金Supported by "Hope for the West" Fund of the Chinese Academy of Science (No. XB 980604)
文摘The low dose effects induced by carbon ions on Chinese hamster V79 cells and murine melanoma B16 cells were investigated in this paper. Both cell lines were divided into four groups for irradiation: (1) control, (2) 0.02 Gy or 0.05 Gy(D1), (3) 1 Gy(D2), (4) D1+D2. The survivors and micronuclei were studied as biological endpoints. The results of group (1) and group (2) showed that there were no obvious differences on micronucleus frequency but there were significant increases when irradiation dose was 0.02Gy on colony formation efficiency. Although low dose ion irradiation could not contribute to DNA damages, it could enhance the colony formation efficiency. In the study of group (3) and (4), when the ion dose was 0.02 Gy, there were evident increases on surviving fraction and decreases on micronucleus frequency, but there were no statistical changes on these endpoints when the ion dose was 0.05Gy. This meant that high LET radiation could induce the adaptive response of cultured cells, furthermore, in the range of inducing ion dose , low dose irradiation was more profitable than high dose one.
基金This work was supported by a grant from NSFC (No.39570188)
文摘WT5”BZ] To study the molecular mechanism of the stimulatory effect of low dose radiation(LDR) on T cell activation. [WT5”BX]Methods.[WT5”BZ] Thymocytes from Kunming mice exposed to whole body irradiation(WBI) with different doses of X rays were analyzed for the changes in signal molecules of the phospholipase C phosphatidylinositol biphosphate(PLC IP2) and G protein adenylate cyclase(AC) pathways. [WT5”BX]Results.[WT5”BZ]It was found that[Ca 2+ ] i increased in response to doses within 0 2 Gy which was most marked after 0 075 Gy and the increase was accentuated in the presence of Con A. The changes in CD3 and calcineurin(CN) expression of the thymocytes followed the same pattern as the alterations in [Ca 2+ ] i after LDR. The expression of α,β1 and β2 isoforms of protein kinase C(PKC) was all up regulated after 0 075 Gy with the increase in PKC β1 expression being most marked. The cAMP/cGMP ratio and PKA activity of the thymocytes was lowered after low dose radiation and increased after doses above 0 5 Gy in a dose dependent manner, thus giving rise to J shaped dose response curves. The Ca antagonist TMB 8 and cAMP stimulant cholera toxin suppressed the augmented thymocyte proliferation induced by LDR. [WT5”BX]Conclusion.[WT5”BZ]Data presented in the present paper suggest that activation of the PLC PIP2 signal pathway and suppression of the AC cAMP signal pathway are involved in the stimulation of the thymocytes following WBI with low dose X rays.
基金supported by the National Natural Science Foundation of China(Nos.61771279,11435007)the National Key Research and Development Program of China(No.2016YFF0101304)
文摘Because of the growing concern over the radiation dose delivered to patients, X-ray cone-beam CT(CBCT) imaging of low dose is of great interest. It is difficult for traditional reconstruction methods such as Feldkamp to reduce noise and keep resolution at low doses. A typical method to solve this problem is using optimizationbased methods with careful modeling of physics and additional constraints. However, it is computationally expensive and very time-consuming to reach an optimal solution. Recently, some pioneering work applying deep neural networks had some success in characterizing and removing artifacts from a low-dose data set. In this study,we incorporate imaging physics for a cone-beam CT into a residual convolutional neural network and propose a new end-to-end deep learning-based method for slice-wise reconstruction. By transferring 3D projection to a 2D problem with a noise reduction property, we can not only obtain reconstructions of high image quality, but also lower the computational complexity. The proposed network is composed of three serially connected sub-networks: a cone-to-fan transformation sub-network, a 2D analytical inversion sub-network, and an image refinement sub-network. This provides a comprehensive solution for end-to-end reconstruction for CBCT. The advantages of our method are that the network can simplify a 3D reconstruction problem to a 2D slice-wise reconstruction problem and can complete reconstruction in an end-to-end manner with the system matrix integrated into the network design. Furthermore, reconstruction can be less computationally expensive and easily parallelizable compared with iterative reconstruction methods.
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supported by the National Natural Science Foundation of China (Grant No. 11205038)the China Postdoctoral Science Foundation (Grant No. 2012M510951)
文摘The radiation effects on several properties （reference voltage, digital output logic voltage, and supply current） of dual 8-bit analog-to-digital （A/D） converters （AD9058） under various biased conditions are investigated in this paper. Gamma ray and 10-MeV proton irradiation are selected for a detailed evaluation and comparison. Based on the measurement results induced by the gamma ray with various dose rates, the devices exhibit enhanced low dose rate sensitivity （ELDRS） under zero and working bias conditions. Meanwhile, it is obvious that the ELDRS is more severe under the working bias condition than under the zero bias condition. The degradation of AD9058 does not display obvious ELDRS during 10-MeV proton irradiation with the selected flux.
文摘目的探讨低辐射剂量扫描联合深度学习重建(DLIR)算法在CT引导下肺穿刺活检中应用的可行性及临床价值。方法选取2023年9月~2024年3月在陕西中医药大学附属医院行CT引导下肺穿刺患者,根据扫描方案不同,将60例肺穿刺活检患者分为常规剂量组(A组)和低剂量组(B组)。A组为100 kV,噪声指数(NI)=15;B组NI=45,其余扫描参数均相同。在常规剂量组中首次和末次全肺扫描分别采用A、B组参数扫描,用于评价深度学习重建算法(DLIR)改善图像质量潜能。A组中首次全肺扫描采用滤波反投影(FBP)和权重为50%自适应统计迭代重建-V(50%ASIR-V)重建,末次全肺扫描采用深度学习重建算法的3种强度(DLIR-L、DLIR-M、DLIR-H)重建图像。分别测量脊柱旁肌肉、皮下脂肪及主动脉血管CT值和SD值,计算信号噪声比(SNR)和对比噪声比(CNR)。对比A、B两组的患者基线特征、穿刺过程中总的辐射剂量、病理阳性率及并发症发生率。结果5种不同条件下重建图像在肌肉、皮下脂肪及主动脉血管处CT值差异无统计学意义(P>0.05),SD值、SNR和CNR值差异有统计学意义(P<0.05),组间两两比较分析显示,DLIR-H图像与50%ASIR-V图像在肌肉、脂肪、血管SD和SNR的差异无统计学意义(P>0.05);FBP vs DLIR-H和DLIR-L vs DLIR-H组的CNR值差异有统计学意义(P<0.05)。与A组总辐射剂量相比,B组总辐射剂量减少约93.6%(P<0.001)。两组图像质量均能满足临床穿刺需要,两组患者的基线特征、病理阳性率及并发症发生率的差异均无统计学意义(P>0.05)。结论低剂量CT扫描结合DLIR重建,可以显著降低图像噪声,提高图像质量,且不影响穿刺安全性和病理阳性率。
