The radiation therapy is applied on around 50% of the cancer patients. As we know, before implementing a radiation treatment planning system in the clinic, the dose-calculation measurement must be validated using rigo...The radiation therapy is applied on around 50% of the cancer patients. As we know, before implementing a radiation treatment planning system in the clinic, the dose-calculation measurement must be validated using rigorous, clinically relevant criteria [1]. Percent Depth Doses (PDD), Dose Profile (DP), Open Collimator Factor (OCF) etc., are measured for all numbers of square fields for Treatment Planning System XiO, version 4.7, for 6 and 15 MV photons energies and for 15°, 30°, 45°, 60° wedge, which were employed to obtain the profiles in any depth. The measurements were conducted also for different energies of electron beam and TPS calculation algorithms.展开更多
In order to derive the linac photon spectrum accurately both the prior constrained model and the genetic algorithm GA are employed using the measured percentage depth dose PDD data and the Monte Carlo simulated monoen...In order to derive the linac photon spectrum accurately both the prior constrained model and the genetic algorithm GA are employed using the measured percentage depth dose PDD data and the Monte Carlo simulated monoenergetic PDDs where two steps are involved.First the spectrum is modeled as a prior analytical function with two parameters αand Ep optimized with the GA.Secondly the linac photon spectrum is modeled as a discretization constrained model optimized with the GA. The solved analytical function in the first step is used to generate initial solutions for the GA’s first run in this step.The method is applied to the Varian iX linear accelerator to derive the energy spectra of its 6 and 15 MV photon beams.The experimental results show that both the reconstructed spectrums and the derived PDDs with the proposed method are in good agreement with those calculated using the Monte Carlo simulation.展开更多
The study is aimed to investigate the effect of the trace element concentrations in healthy and cancerous prostate tissues on dose distributions in radiotherapy. In this work, the trace element compounds completely so...The study is aimed to investigate the effect of the trace element concentrations in healthy and cancerous prostate tissues on dose distributions in radiotherapy. In this work, the trace element compounds completely soluble in the water were used and their concentrations given in the literature were mixed homogeneously with pure water. This is the first time study in literature as far as we know. The percent depth dose (PDD) measurements were performed using Elekta Synergy Platform Linac device for 6 and 18 MV photon energies. We also obtained the PDDs results by choosing higher trace element concentrations than given in literature in cancerous prostate tissue to see the effect on radiotherapy. The experimental measurements were compared with the results obtained from the GATE simulation code. The TPR<sub>20/10</sub> was calculated for 10 × 10 cm<sup>2</sup> field size at 6/18 MV energies photons and compared with simulation results. The differences between simulation and measurement for 6 MV and 18 MV photons are 1.75% and 1.82% respectively. The experimental results and simulations were presented an uncertainty lower than 3%. Simulated dose values are in good agreement with less than 2% differences with the experimental results. We see that the trace element concentrations of healthy and cancerous tissues did not affect the dose distribution at high-energy photons. This is expected and well known result. We believe that this <em>in vitro</em> study is important for proving the reliability of the dose given in radiotherapy treatment once again.展开更多
In this paper,the beam quality and percent depth dose curves for different field sizes of CyberKnife? system were investigated by Monte Carlo simulations using the PENELOPE code,which has been used to simulate 6 MV ph...In this paper,the beam quality and percent depth dose curves for different field sizes of CyberKnife? system were investigated by Monte Carlo simulations using the PENELOPE code,which has been used to simulate 6 MV photon beam.In water phantom,the absolute doses were calculated for Φ10–60 mm collimators,and percent depth dose curves were evaluated for Φ30–60 mm collimators.The agreement of dose distributions of the calculation with measurement was within 3.0%.The mean energy of photon spectrum was 1.46 MeV,and the beam quality index was 0.632,which was slightly smaller than that of measurement.展开更多
高能医用直线加速器在放射治疗中的应用越来越广泛,其辐射源项及屏蔽防护研究一直是人们关注的重点。应用MCNP(Monte Carlo N-Particle Transport Code)软件对Clinac 23EX型医用直线加速器产生的15 MV X射线束进行模拟。依据厂家提供的...高能医用直线加速器在放射治疗中的应用越来越广泛,其辐射源项及屏蔽防护研究一直是人们关注的重点。应用MCNP(Monte Carlo N-Particle Transport Code)软件对Clinac 23EX型医用直线加速器产生的15 MV X射线束进行模拟。依据厂家提供的机头内部件的材料组成和几何尺寸,构建X射线模式的加速器机头精细模型,计算了不同照射野下X射线束在水模体中的百分深度剂量(Percentage Depth Dose,PDD)曲线和剖面相对剂量(Profile)曲线。模拟计算结果与三维水箱的实测结果基本吻合,表明本研究建立的模型准确可靠,可应用于后续医用直线加速器各类辐射源项的研究。另外,通过分析机头不同组件对X射线束能谱及穿透能力的影响程度,可为优化屏蔽设计和放疗计划提供参考。展开更多
In this paper,we have addressed the problem of the radiation transport with the Monte Carlo N-particle(MCNP) code.This is a general-purpose Monte Carlo tool designed to transport neutron,photon and electron in three d...In this paper,we have addressed the problem of the radiation transport with the Monte Carlo N-particle(MCNP) code.This is a general-purpose Monte Carlo tool designed to transport neutron,photon and electron in three dimensional geometries.To examine the performance of MCNP5 code in the field of external radiotherapy,we performed the modeling of an Electron Density phantom(EDP) irradiated by photons from 60Co source.The model was used to calculate the Percent Depth Dose(PDD) at different depths in an EDP.One field size for PDD has been examined.A 60Co photons source placed at 80 cm source to surface distance(SSD).The results of calculations were compared to TPS data obtained at National Institute of Oncology of Rabat.展开更多
文摘The radiation therapy is applied on around 50% of the cancer patients. As we know, before implementing a radiation treatment planning system in the clinic, the dose-calculation measurement must be validated using rigorous, clinically relevant criteria [1]. Percent Depth Doses (PDD), Dose Profile (DP), Open Collimator Factor (OCF) etc., are measured for all numbers of square fields for Treatment Planning System XiO, version 4.7, for 6 and 15 MV photons energies and for 15°, 30°, 45°, 60° wedge, which were employed to obtain the profiles in any depth. The measurements were conducted also for different energies of electron beam and TPS calculation algorithms.
文摘In order to derive the linac photon spectrum accurately both the prior constrained model and the genetic algorithm GA are employed using the measured percentage depth dose PDD data and the Monte Carlo simulated monoenergetic PDDs where two steps are involved.First the spectrum is modeled as a prior analytical function with two parameters αand Ep optimized with the GA.Secondly the linac photon spectrum is modeled as a discretization constrained model optimized with the GA. The solved analytical function in the first step is used to generate initial solutions for the GA’s first run in this step.The method is applied to the Varian iX linear accelerator to derive the energy spectra of its 6 and 15 MV photon beams.The experimental results show that both the reconstructed spectrums and the derived PDDs with the proposed method are in good agreement with those calculated using the Monte Carlo simulation.
文摘The study is aimed to investigate the effect of the trace element concentrations in healthy and cancerous prostate tissues on dose distributions in radiotherapy. In this work, the trace element compounds completely soluble in the water were used and their concentrations given in the literature were mixed homogeneously with pure water. This is the first time study in literature as far as we know. The percent depth dose (PDD) measurements were performed using Elekta Synergy Platform Linac device for 6 and 18 MV photon energies. We also obtained the PDDs results by choosing higher trace element concentrations than given in literature in cancerous prostate tissue to see the effect on radiotherapy. The experimental measurements were compared with the results obtained from the GATE simulation code. The TPR<sub>20/10</sub> was calculated for 10 × 10 cm<sup>2</sup> field size at 6/18 MV energies photons and compared with simulation results. The differences between simulation and measurement for 6 MV and 18 MV photons are 1.75% and 1.82% respectively. The experimental results and simulations were presented an uncertainty lower than 3%. Simulated dose values are in good agreement with less than 2% differences with the experimental results. We see that the trace element concentrations of healthy and cancerous tissues did not affect the dose distribution at high-energy photons. This is expected and well known result. We believe that this <em>in vitro</em> study is important for proving the reliability of the dose given in radiotherapy treatment once again.
基金Supported by Shanghai Science and Technology Committee (08JC1410200)Shanghai Leading Academic Disciplines (S30109)
文摘In this paper,the beam quality and percent depth dose curves for different field sizes of CyberKnife? system were investigated by Monte Carlo simulations using the PENELOPE code,which has been used to simulate 6 MV photon beam.In water phantom,the absolute doses were calculated for Φ10–60 mm collimators,and percent depth dose curves were evaluated for Φ30–60 mm collimators.The agreement of dose distributions of the calculation with measurement was within 3.0%.The mean energy of photon spectrum was 1.46 MeV,and the beam quality index was 0.632,which was slightly smaller than that of measurement.
文摘高能医用直线加速器在放射治疗中的应用越来越广泛,其辐射源项及屏蔽防护研究一直是人们关注的重点。应用MCNP(Monte Carlo N-Particle Transport Code)软件对Clinac 23EX型医用直线加速器产生的15 MV X射线束进行模拟。依据厂家提供的机头内部件的材料组成和几何尺寸,构建X射线模式的加速器机头精细模型,计算了不同照射野下X射线束在水模体中的百分深度剂量(Percentage Depth Dose,PDD)曲线和剖面相对剂量(Profile)曲线。模拟计算结果与三维水箱的实测结果基本吻合,表明本研究建立的模型准确可靠,可应用于后续医用直线加速器各类辐射源项的研究。另外,通过分析机头不同组件对X射线束能谱及穿透能力的影响程度,可为优化屏蔽设计和放疗计划提供参考。
基金Laboratory of Radiation and Nuclear Systems (LRSN)
文摘In this paper,we have addressed the problem of the radiation transport with the Monte Carlo N-particle(MCNP) code.This is a general-purpose Monte Carlo tool designed to transport neutron,photon and electron in three dimensional geometries.To examine the performance of MCNP5 code in the field of external radiotherapy,we performed the modeling of an Electron Density phantom(EDP) irradiated by photons from 60Co source.The model was used to calculate the Percent Depth Dose(PDD) at different depths in an EDP.One field size for PDD has been examined.A 60Co photons source placed at 80 cm source to surface distance(SSD).The results of calculations were compared to TPS data obtained at National Institute of Oncology of Rabat.
