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您的检索式：作者名="Pablo Yepes"
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| 1 | Comparison of pencil beam and Monte Carlo calculations with ion chamber array measurements for patient-specific quality assurance显示文摘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.Methods: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 index.Results: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 Syngo.For proton portals with RS,more than 80%of measurements would agree with both calculations using the same criteria.For 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 cal-culations.For 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 calculations.Conclusions:Both the pencil beam algorithm in Syngo and the FDC algorithm in TIMPS can provide accurate dose calculations in water for most clinical portals.For 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 time.There 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. | Yu Deng Zhi Chen Qianxia Wang Pablo Yepes Zhuangming Shen Hongliang Chen Jie Li Michael F.Moyers | 2022 | Radiation Medicine and Protection2022，3，3： | 2 |
| 2 | Implementation of Monte Carlo based PET verification of ion beam delivery into a TPS显示文摘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)scans.Methods: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 beams.These distribu-tions are processed to simulate PET images taking into account positron diffusion,radioactive decay,biological washout,and detector blurring.Additional tools were developed to register simulated PET images with planning CT images and perform comparisons of measured and simulated PET images.Results:Production cross-sections were generated for various isotopes and materials.Treatment plans for several different body sites were used to verify the functioning and utility of the new tools for both proton and carbon ion beams.Conclusions:Several tools have been developed to simulate PET scans of patients irradiated with ion beams and compare the simulated images to measurements.After commissioning and implementation into the clinic,the appropriate sizes for margins that account for uncertainties may be investigated. | Pablo Yepes Zhuangming Shen Michael F.Moyers Qianxia Wang Hongliang Chen Jie Li Yongqiang Li James Lin | 2022 | Radiation Medicine and Protection2022，3，3： | 1 |
| 3 | Verification of an independent dose calculation method for portal-specific QA of proton and carbon ion beams显示文摘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 TPS.Methods:A Monte Carlo based track repeating algorithm was incorporated into an in-house treatment planning system for proton and carbon ion beams.Calculations 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 portals.The comparisons utilized a Gamma analysis.Results:A total of 124 measurements were performed for proton and carbon ion patient portals.Using 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,respectively.The passing rate was substantially higher for Monte Carlo calculations than for pencil beam calculations for portals that used a range shifter.Conclusions:The implemented independent method has been verified against measurements.The high passing rate with small tolerances leads to the possibility of reducing the number of required quality assurance measurements. | Michael F.Moyers Qianxia Wang Yu Deng Hongliang Chen Zhi Chen Xiaoli Liu Nicki Schlegel Jie Li Zhuangming Shen James Lin Pablo Yepes | 2022 | Radiation Medicine and Protection2022，3，3： | 1 |
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