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一种医学图像局部结构的尺度选择方法

中国医疗器械杂志 2013年第4期37卷 248-251页

作者：沈庄明秦斌杰上海交通大学生物医学工程学院上海市200240

局部结构的尺度信息是医学图像配准中一个重要的参数。然而,现有的图像配准研究大多没有关注对图像局部结构尺度的选择。该文提出了一种数据驱动的局部结构尺度选择方法,通过基于最小描述长度准则的后验概率最大化和基于马尔科夫随机场... 详细信息

局部结构的尺度信息是医学图像配准中一个重要的参数。然而,现有的图像配准研究大多没有关注对图像局部结构尺度的选择。该文提出了一种数据驱动的局部结构尺度选择方法,通过基于最小描述长度准则的后验概率最大化和基于马尔科夫随机场模型的空间一致性约束,从各向异性的离散尺度空间中,为每一个经超像素分割得到的局部结构分配最佳的尺度,以满足后续非刚性医学图像配准中对局部结构尺度信息的需求。

关键词：尺度选择超像素最小描述长度马尔科夫随机场

Implementation of Monte Carlo based PET verification of ion beam delivery into a TPS

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Radiation Medicine and Protection 2022年第3期3卷 131-138页

作者： Pablo Yepes zhuangming shen Michael F.Moyers Qianxia Wang Hongliang Chen Jie Li Yongqiang Li James Lin Rice University HoustonTX77005USA Shanghai Proton and Heavy Ion Center Shanghai Engineering Research Center of Proton and Heavy Ion Radiation TherapyShanghai 201315China

Objective:To develop and implement an ion beam teletherapy verification system based upon simulations of induced radioactivity and comparison with patient positron emission tomography(PET)***:A Monte Carlo algorithm was integrated into an in-house built treatment,information,management,and planning system(TIMPS■)to calculate distributions of positron emitters induced by ion *** distribu-tions are processed to simulate PET images taking into account positron diffusion,radioactive decay,biological washout,and detector *** tools were developed to register simulated PET images with planning CT images and perform comparisons of measured and simulated PET ***:Production cross-sections were generated for various isotopes and *** plans for several different body sites were used to verify the functioning and utility of the new tools for both proton and carbon ion ***:Several tools have been developed to simulate PET scans of patients irradiated with ion beams and compare the simulated images to *** commissioning and implementation into the clinic,the appropriate sizes for margins that account for uncertainties may be investigated.

关键词： ion beam PET Monte Carlo

Comparison of pencil beam and Monte Carlo calculations with ion chamber array measurements for patient-specific quality assurance

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Radiation Medicine and Protection 2022年第3期3卷 115-122页

作者： Yu Deng Zhi Chen Qianxia Wang Pablo Yepes zhuangming shen Hongliang Chen Jie Li Michael F.Moyers Shanghai Proton and Heavy Ion Center Shanghai Engineering Research Center of Proton and Heavy Ion Radiation TherapyShanghai 201315China Rice University HoustonTX77005USA

Objective:To determine under what conditions and criteria comparisons between calculations made with the current clinical treatment planning system(Syngo)and an in-house built TPS(TIMPS)would allow skipping of in-beam portal-specific ***:Measurements were made with an array of 24 ion chambers in a water phantom for 227 proton and 313 carbon ion portals with and without a range shifter(RS).These measurements were compared with calculations performed with Syngo and TIMPS using metrics of average dose difference and Gamma ***:For proton portals without RS,if a Gamma comparison between TIMPS and Syngo passed using criteria of 90%of tested points being within 3%and 3 mm,then 74%of measurements would agree with both TIMPS and *** proton portals with RS,more than 80%of measurements would agree with both calculations using the same *** carbon ion portals without RS,if a Gamma evaluation between TIMPS and Syngo passed with criteria of 90%of tested points being within 2%and 2 mm,85%of measurements would agree with both *** carbon ion portals with RS,if a Gamma evaluation between TIMPS and Syngo passed with criteria of 90%of tested points being within 3%and 3 mm,60%of measurements would agree with both ***:Both the pencil beam algorithm in Syngo and the FDC algorithm in TIMPS can provide accurate dose calculations in water for most clinical *** about 75%of portals,physicists can perform comparisons of calculations instead of phantom measurements to verify Syngo calculations thereby saving a large amount of beam *** are some portals,however,such as for low-energy protons without RS and high-energy carbon ions,where agreement between the two calculations and measurements are not yet satisfactory to allow the elimination of all measurements.

关键词： Ion beam Quality assurance Monte Carlo Pencil beam

Verification of an independent dose calculation method for portal-specific QA of proton and carbon ion beams

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Radiation Medicine and Protection 2022年第3期3卷 152-157页

作者： Michael F.Moyers Qianxia Wang Yu Deng Hongliang Chen Zhi Chen Xiaoli Liu Nicki Schlegel Jie Li zhuangming shen James Lin Pablo Yepes Shanghai Proton and Heavy Ion Center Shanghai 201315China Shanghai Engineering Research Center of Proton and Heavy Ion Radiation Therapy Shanghai 201315China Rice University HoustonTXUSA

Objective:To verify the accuracy of an independent dose calculation method,as incorporated into an in-house developed treatment planning system(TPS),for performing quality assurance of dose distributions delivered to a water phantom planned by a clinical ***:A Monte Carlo based track repeating algorithm was incorporated into an in-house treatment planning system for proton and carbon ion *** were performed in a flat water phantom for both a traditional pencil beam algorithm and a new Monte Carlo algorithm,and then compared to measurements made at multiple depths with a 2D ionization array for 44 patient *** comparisons utilized a Gamma ***:A total of 124 measurements were performed for proton and carbon ion patient *** a small Gamma criteria of 2%/2 mm,an average of 93%and 97%of measurement points passed for each portal for pencil beam and Monte Carlo calculations,*** passing rate was substantially higher for Monte Carlo calculations than for pencil beam calculations for portals that used a range ***:The implemented independent method has been verified against *** high passing rate with small tolerances leads to the possibility of reducing the number of required quality assurance measurements.

关键词： Ion beam Quality assurance Monte Carlo Ionization chamber array