Objective:Using GATE to do Monte Carlo simulation in nuclear medicine imaging SPECT and PET,photon and proton radiation therapy.To research the influence of carbon fiber bed in the dose distribution for photon radiation.Methods:First,three examples corresponding to SPECT,PET and RT which includes photon therapy and proton therapy provided by GATE V6.1 were simulated.The scattering of photons in SPECT and PET simulation and energy deposition characteristics of the photon beam and the proton beam in a water phantom in the RT simulation were analyzed.Then,photon therapy beam was launched into the water phantom with carbon fiber bed in the simulation.The simulation was repeated but without carbon fiber bed.The difference of dose distribution in the water phantom in both cases were compared and analyzed.Results:In the three examples,non-scattered photons stabilized at around 36％ in the SPECT and true coincidence without scattering stabilized at about 44.5％ in the PET.The dose distribution of proton was much better than photon in the depth direction,and dose distribution of photon was slightly better than proton in the lateral direction.The surface dose of the water phantom significantly improved when the carbon fiber bed was added in the simulation.Conclusions:GATE is a stable and accurate Monte Carlo simulation platform in nuclear medicine imaging and radiation therapy.It can be a powerful tool for researchers in the dose verification,clinical treatment planning and nuclear medicine imaging guided radiation therapy.%目的:探讨GATE在核医学成像SPECT和PET、光子和质子放射治疗中的蒙特卡洛模拟,并利用GATE平台研究碳纤维床板对光子放疗时剂量的影响.方法:首先模拟运行GATE V6.1提供的三个例子,分别对应于SPECT、PET和RT,其中RT又分为光子治疗和质子治疗.对SPECT和PET模拟中光子的散射情况进行统计分析,详细比较RT模拟中光子束和质子束在水模体中的能量沉积特性.然后在GATE平台上编程模拟了光子治疗束分别在有碳纤维床板和无床板时射入水模体中,比较并分析这两种情况下水模体中的剂量分布差异.结果:GATE V6.1的三个例子模拟中,SPECT中的未散射光子稳定在36％左右,PET中未散射的真符合计数稳定在44.5％左右,RT模拟中质子相比于光子在深度方向上有明显的剂量分布优势,而光子在横向方向的剂量分布稍好于质子.在碳纤维床板对光子放疗时剂量影响的模拟中,有碳纤维床板相对于无床板时,水模体的表层剂量有明显的提高.结论:GATE能够稳定准确的对核医学成像SPECT和PET及放射治疗过程进行蒙特卡洛模拟.它可以为放射治疗剂量验证、临床放射治疗计划以及核医学成像引导放射治疗的研究提供强大帮助.
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