Objective：To study the effect of iodine-125 interstitial brachytherapy on liver cancer. Methods： Animal model of human liver cancer was established by injecting SMMC-7721 cells cultivated in vitro subcutaneously int...Objective：To study the effect of iodine-125 interstitial brachytherapy on liver cancer. Methods： Animal model of human liver cancer was established by injecting SMMC-7721 cells cultivated in vitro subcutaneously into the flank of BALB/c nude mice. Nude mice with tumor of 5 mm in diameter were randomly divided into 2 groups （n = 10）. One iodine-125 seed of apparent activity 0.8 mCi was implanted into the center of tumor in treatment group, whereas an inactive seed was implanted in control group. The other 20 nude mice with tumor reaching 10 mm in diameter were also treated as above. The size of tumor was determined weekly after implantation, and pathological examination and blood routine were taken on the 28th day. Results： Tumor growth was obviously inhibited in treatment group of tumor of 5 mm in diameter, and there was statistically significant difference in tumor volume between treatment and control groups （P〈0.01）. Around iodine-125 seed, apparent necrosis of tumor was shown in treatment group, accompanied by karyopyknosis and reduced plasma in residual tumor cells microscopically. Tumor growth was not inhibited in either treatment or control group of tumor of 10 mm in diameter. There was no obvious adverse effect except for decreased white blood cells in treatment groups. Conclusion： There is certain effect of iodine-125 interstitial braehytherapy on liver cancer, which is associated with the size of tumor.展开更多
The Monte Carlo(MC)simulation is regarded as the gold standard for dose calculation in brachytherapy,but it consumes a large amount of computing resources.The development of heterogeneous computing makes it possible t...The Monte Carlo(MC)simulation is regarded as the gold standard for dose calculation in brachytherapy,but it consumes a large amount of computing resources.The development of heterogeneous computing makes it possible to substantially accelerate calculations with hardware accelerators.Accordingly,this study develops a fast MC tool,called THUBrachy,which can be accelerated by several types of hardware accelerators.THUBrachy can simulate photons with energy less than 3 MeV and considers all photon interactions in the energy range.It was benchmarked against the American Association of Physicists in Medicine Task Group No.43 Report using a water phantom and validated with Geant4 using a clinical case.A performance test was conducted using the clinical case,showing that a multicore central processing unit,Intel Xeon Phi,and graphics processing unit(GPU)can efficiently accelerate the simulation.GPU-accelerated THUBrachy is the fastest version,which is 200 times faster than the serial version and approximately 500 times faster than Geant4.The proposed tool shows great potential for fast and accurate dose calculations in clinical applications.展开更多
The purpose of this study is to investigate and quantify the influence of nanoparticle composition,size,and concentration on the difference between dose enhancement values derived from Monte Carlo simulations with hom...The purpose of this study is to investigate and quantify the influence of nanoparticle composition,size,and concentration on the difference between dose enhancement values derived from Monte Carlo simulations with homogeneous and structured geometrical representations of the target region in metal nanoparticle-enhanced photon brachytherapy.Values of the dose enhancement factor(DEF)were calculated for Pd-103,I-125,and Cs-131 brachytherapy sources with gold,silver,or platinum nanoparticles acting as targeting agents.Simulations were performed using the Geant4 toolkit with condensed history models of electron transport.Stringent limits were imposed on adjustable parameters that define secondary electron histories,so that simulations came closest to true event-byevent electron tracking,thereby allowing part of the nanoparticle-laden volume used for calculating the dose to be represented as a structured region with uniformly distributed discrete nanoparticles.Fine-tuned physical models of secondary radiation emission and propagation,along with the discrete geometrical representation of nanoparticles,result in a more realistic assessment of dose enhancement.The DEF correction coefficient is introduced as a metric that quantifies the absorption of secondary radiation inside the nanoparticles themselves,a phenomenon disregarded when the target region is treated as a homogeneous metal–tissue mixture,but accounted for by discrete nanoparticle representation.The approach applied to correcting DEF values both draws from and expands upon several related investigations published previously.Comparison of the obtained results to those found in relevant references shows both agreement and deviation,depending on nanoparticle properties and photon energy.展开更多
Objective: To observe the process of tumor response to interstitial brachytherapy of intracranial germinomas during and immediately after the therapy. Methods: Fractionated brachytherapy using 192 Ir was used in 13 pa...Objective: To observe the process of tumor response to interstitial brachytherapy of intracranial germinomas during and immediately after the therapy. Methods: Fractionated brachytherapy using 192 Ir was used in 13 patients with intracranial germinomas. The average age at diagnosis was 14.3 years (range 5-27 years). The frequency of fractionation had been increased stepwise from 3 fractionations within 5 d in the past to 26-30 fractionations in 15-20 d at present. Results: Of 9 pineal tumors, the average reduction of tumor volume was 73.2% at a cumulated radiation dose of 20 Gy and 85.3% at 30 Gy, respectively. In 4 cases of basal ganglia and thalamus areas tumors, the reduction of tumor volume was from an average 56.1% at a cumulated radiation dose of 30 Gy to 75.2% at the end of therapy. That intratumoral hemorrhage was absorbed quickly accompanying tumor regression was demonstrated in all but one patient; 6 patients died; 7 patients were still in follow-up without any evidence of tumor recurrence. Conclusion: Interstitial brachytherapy could be given as the first optional therapy for intracranial germinomas. The histological diagnosis of germinomas can be verified by stereotactic biopsy simultaneously. Germinoma is one of the sensitive tumors to interstitial brachytherapy. The radiation injury to surrounding brain tissue could be reduced by using a conformal dynamic brachytherapy.展开更多
文摘Objective：To study the effect of iodine-125 interstitial brachytherapy on liver cancer. Methods： Animal model of human liver cancer was established by injecting SMMC-7721 cells cultivated in vitro subcutaneously into the flank of BALB/c nude mice. Nude mice with tumor of 5 mm in diameter were randomly divided into 2 groups （n = 10）. One iodine-125 seed of apparent activity 0.8 mCi was implanted into the center of tumor in treatment group, whereas an inactive seed was implanted in control group. The other 20 nude mice with tumor reaching 10 mm in diameter were also treated as above. The size of tumor was determined weekly after implantation, and pathological examination and blood routine were taken on the 28th day. Results： Tumor growth was obviously inhibited in treatment group of tumor of 5 mm in diameter, and there was statistically significant difference in tumor volume between treatment and control groups （P〈0.01）. Around iodine-125 seed, apparent necrosis of tumor was shown in treatment group, accompanied by karyopyknosis and reduced plasma in residual tumor cells microscopically. Tumor growth was not inhibited in either treatment or control group of tumor of 10 mm in diameter. There was no obvious adverse effect except for decreased white blood cells in treatment groups. Conclusion： There is certain effect of iodine-125 interstitial braehytherapy on liver cancer, which is associated with the size of tumor.
基金supported by the National Natural Science Foundation of China(No.11875036)。
文摘The Monte Carlo(MC)simulation is regarded as the gold standard for dose calculation in brachytherapy,but it consumes a large amount of computing resources.The development of heterogeneous computing makes it possible to substantially accelerate calculations with hardware accelerators.Accordingly,this study develops a fast MC tool,called THUBrachy,which can be accelerated by several types of hardware accelerators.THUBrachy can simulate photons with energy less than 3 MeV and considers all photon interactions in the energy range.It was benchmarked against the American Association of Physicists in Medicine Task Group No.43 Report using a water phantom and validated with Geant4 using a clinical case.A performance test was conducted using the clinical case,showing that a multicore central processing unit,Intel Xeon Phi,and graphics processing unit(GPU)can efficiently accelerate the simulation.GPU-accelerated THUBrachy is the fastest version,which is 200 times faster than the serial version and approximately 500 times faster than Geant4.The proposed tool shows great potential for fast and accurate dose calculations in clinical applications.
基金supported by the Ministry of Education,Science and Technological Development of the Republic of Serbia under contracts TR-37021 and 171007。
文摘The purpose of this study is to investigate and quantify the influence of nanoparticle composition,size,and concentration on the difference between dose enhancement values derived from Monte Carlo simulations with homogeneous and structured geometrical representations of the target region in metal nanoparticle-enhanced photon brachytherapy.Values of the dose enhancement factor(DEF)were calculated for Pd-103,I-125,and Cs-131 brachytherapy sources with gold,silver,or platinum nanoparticles acting as targeting agents.Simulations were performed using the Geant4 toolkit with condensed history models of electron transport.Stringent limits were imposed on adjustable parameters that define secondary electron histories,so that simulations came closest to true event-byevent electron tracking,thereby allowing part of the nanoparticle-laden volume used for calculating the dose to be represented as a structured region with uniformly distributed discrete nanoparticles.Fine-tuned physical models of secondary radiation emission and propagation,along with the discrete geometrical representation of nanoparticles,result in a more realistic assessment of dose enhancement.The DEF correction coefficient is introduced as a metric that quantifies the absorption of secondary radiation inside the nanoparticles themselves,a phenomenon disregarded when the target region is treated as a homogeneous metal–tissue mixture,but accounted for by discrete nanoparticle representation.The approach applied to correcting DEF values both draws from and expands upon several related investigations published previously.Comparison of the obtained results to those found in relevant references shows both agreement and deviation,depending on nanoparticle properties and photon energy.
文摘Objective: To observe the process of tumor response to interstitial brachytherapy of intracranial germinomas during and immediately after the therapy. Methods: Fractionated brachytherapy using 192 Ir was used in 13 patients with intracranial germinomas. The average age at diagnosis was 14.3 years (range 5-27 years). The frequency of fractionation had been increased stepwise from 3 fractionations within 5 d in the past to 26-30 fractionations in 15-20 d at present. Results: Of 9 pineal tumors, the average reduction of tumor volume was 73.2% at a cumulated radiation dose of 20 Gy and 85.3% at 30 Gy, respectively. In 4 cases of basal ganglia and thalamus areas tumors, the reduction of tumor volume was from an average 56.1% at a cumulated radiation dose of 30 Gy to 75.2% at the end of therapy. That intratumoral hemorrhage was absorbed quickly accompanying tumor regression was demonstrated in all but one patient; 6 patients died; 7 patients were still in follow-up without any evidence of tumor recurrence. Conclusion: Interstitial brachytherapy could be given as the first optional therapy for intracranial germinomas. The histological diagnosis of germinomas can be verified by stereotactic biopsy simultaneously. Germinoma is one of the sensitive tumors to interstitial brachytherapy. The radiation injury to surrounding brain tissue could be reduced by using a conformal dynamic brachytherapy.
