TEPC壁对重离子束微剂量学测量及相对生物学效应计算的影响
|
摘要
组织等效正比计数器(TEPC)广泛应用于重离子束微剂量学测量,提供用于计算相对生物学效应(RBE)的基础数据。为研究TEPC壁对重离子束微剂量学测量及RBE计算的影响,在蒙特卡罗(MC)模拟中引入理想组织等效正比计数器(Ideal-TEPC),精确计算得到碳离子束不同水等效深度处的微剂量学量及RBE。Ideal-TEPC和常规TEPC的计算结果表明:TEPC壁会使碳离子束产生较大的辐射场畸变,且会使TEPC测量结果及RBE计算结果产生较大偏差,该偏差随贯穿深度的增加而增大。将TEPC壁视为具有固定水等效厚度的水层可在数值上抵消TEPC壁对RBE计算的影响,但在展宽Bragg峰(SOBP)后端会产生过修正现象。Ideal-TEPC结合MC模拟能有效避免TEPC壁效应及TEPC壁引起的辐射场畸变对重离子束微剂量学量和RBE计算的影响。
Tissue equivalent proportional counter(TEPC) is widely used for microdosimetric measurements in heavy ion beams, which provides basic data for calculating relative biological effectiveness(RBE). To study the influence of TEPC wall on microdosimetric measurements and RBE calculations of heavy ion beams, an Ideal-TEPC combined with Monte Carlo(MC) simulation was introduced to accurately calculate the microdosimetric quantities and RBE at different water equivalent depths of carbon ion beams. The results using Ideal-TEPC and general TEPC show that the TEPC wall produces serious irradiation field distortions for the carbon ion beams, and leads to deviation for the results of TEPC measurements and the RBE calculations. The deviation increases with the penetration depth. Treating the TEPC wall as a water layer with a fixed water equivalent thickness could numerically offset the influence of the TEPC wall on the RBE calculation, but over-correction occurs at the distal end of the spread-out Bragg peak(SOBP). Using Ideal-TEPC combined with MC simulation, the influence of wall effect and irradiation field distortions caused by TEPC wall on microdosimetric measurements and RBE calculations of heavy ion beam can be effectively avoided.
Tissue equivalent proportional counter(TEPC) is widely used for microdosimetric measurements in heavy ion beams, which provides basic data for calculating relative biological effectiveness(RBE). To study the influence of TEPC wall on microdosimetric measurements and RBE calculations of heavy ion beams, an Ideal-TEPC combined with Monte Carlo(MC) simulation was introduced to accurately calculate the microdosimetric quantities and RBE at different water equivalent depths of carbon ion beams. The results using Ideal-TEPC and general TEPC show that the TEPC wall produces serious irradiation field distortions for the carbon ion beams, and leads to deviation for the results of TEPC measurements and the RBE calculations. The deviation increases with the penetration depth. Treating the TEPC wall as a water layer with a fixed water equivalent thickness could numerically offset the influence of the TEPC wall on the RBE calculation, but over-correction occurs at the distal end of the spread-out Bragg peak(SOBP). Using Ideal-TEPC combined with MC simulation, the influence of wall effect and irradiation field distortions caused by TEPC wall on microdosimetric measurements and RBE calculations of heavy ion beam can be effectively avoided.
引文
[1] KRAFT G.Tumor therapy with heavy charged particles[J].Prog Part Nucl Phys,2000.doi:10.1016/S0146-6410(00)00112-5.
[2] TSUJII H,KAMADA T,SHIRAI T,et al.Carbon-ion radiotherapy:Principles,practices,and treatment planning[M].Germany:Springer,2014.
[3] TORIKOSHI M,MINOHARA S,KANEMATSU N,et al.Irradiation system for HIMAC[J].J Radiat Res,2007.doi:10.1269/jrr.48.A15.
[4] YAN Y,MA Y,JI T,et al.Spot-scanning beam delivery with laterally- and longitudinally-mixed spot size pencil beams in heavy ion radiotherapy[J].Chinese Physics C,2017,41(9):098201.
[5] HE P,LI Q,LIU X,et al.Experimental measurement of the correlation between CT number and heavy ion range[J].Chinese Physics C,2012,36(10):954-957.
[6] MIHAILESCU D,BORCIA C.Biophysical models in hadrontherapy[J].Journal of Advanced Research in Physics,2012,3(1):1-9.
[7] SCHARDT D,ELS?SSER T,SCHULZ-ERTNER D.Heavy-ion tumor therapy:Physical and radiobiological benefits[J].Reviews of Modern Physics,2010,82(1):383-425.
[8] DAI T,LI Q,CHEN W.Dependence of relative biological effectiveness on dose in hypofractionated carbon ion beam radiotherapy[J].Nuclear Physics Review,2017,34(4):784-790.
[9] HAWKINS R.A microdosimetric-kinetic model of cell death from exposure to ionizing radiation of any LET,with experimental and clinical appli-cations[J].International Journal of Radiation Biology,1996,69(6):739-755.
[10] SCHOLZ M,KELLERER A,KRAFT-WEYRATHER W,et al.Computation of cell survival in heavy ion beams for therapy:The model and its approximation[J].Radiat Environ Biophys,1997,36:59-66.
[11] SELLNER S.Simulations,optimizations and microdosimetric measurements of beam quality for heavy-ion tumor therapy[J].CMES-Computer Modeling in Engineering & Sciences,2013,95(3):177-204.
[12] IVANCHENKO V,INCERTI S,FRANCIS Z,et al.Combination of electromagnetic physics processes for microdosimetry in liquid water with the Geant4 Monte Carlo simulation toolkit[J].Nuclear Instruments and Methods in Physics Research B,2012,273:95-97.
[13] BURIGO L,PSHENICHNOV I,MISHUSTIN I,et al.Microdosimetry of radiation field from a therapeutic 12C beam in water:A study with Geant4 toolkit[J].Nuclear Instruments and Methods in Physics Research B,2013,310:37-53.
[14] KANAI T,FURUSAWA Y,FUKUTSU K,et al.Irradiation of mixed beam and design of spread-out Bragg peak for heavy-ion radiotherapy[J].Radiation Research,1997,147(1):78-84.
[15] KASE Y,KANAI T,MATSUMOTO Y,et al.Microdosimetric measurements and estimation of human cell survival for heavy-ion beams[J].Radiation Research,2006,166(4):629-638.
[16] KASE Y,KANAI T,SAKAMA M,et al.Microdosimetric approach to NIRS-defined biological dose measurement for carbon-ion treatment beam[J].Journal of Radiation Research,2011,52(1):59-68.
[17] GALER S,SHIPLEY D,PALMANS H,et al.Monte Carlo simulation of a TEPC for microdosimetry of carbon ions[J].Radiation Physics and Chemistry,2017,140:412-418.
[2] TSUJII H,KAMADA T,SHIRAI T,et al.Carbon-ion radiotherapy:Principles,practices,and treatment planning[M].Germany:Springer,2014.
[3] TORIKOSHI M,MINOHARA S,KANEMATSU N,et al.Irradiation system for HIMAC[J].J Radiat Res,2007.doi:10.1269/jrr.48.A15.
[4] YAN Y,MA Y,JI T,et al.Spot-scanning beam delivery with laterally- and longitudinally-mixed spot size pencil beams in heavy ion radiotherapy[J].Chinese Physics C,2017,41(9):098201.
[5] HE P,LI Q,LIU X,et al.Experimental measurement of the correlation between CT number and heavy ion range[J].Chinese Physics C,2012,36(10):954-957.
[6] MIHAILESCU D,BORCIA C.Biophysical models in hadrontherapy[J].Journal of Advanced Research in Physics,2012,3(1):1-9.
[7] SCHARDT D,ELS?SSER T,SCHULZ-ERTNER D.Heavy-ion tumor therapy:Physical and radiobiological benefits[J].Reviews of Modern Physics,2010,82(1):383-425.
[8] DAI T,LI Q,CHEN W.Dependence of relative biological effectiveness on dose in hypofractionated carbon ion beam radiotherapy[J].Nuclear Physics Review,2017,34(4):784-790.
[9] HAWKINS R.A microdosimetric-kinetic model of cell death from exposure to ionizing radiation of any LET,with experimental and clinical appli-cations[J].International Journal of Radiation Biology,1996,69(6):739-755.
[10] SCHOLZ M,KELLERER A,KRAFT-WEYRATHER W,et al.Computation of cell survival in heavy ion beams for therapy:The model and its approximation[J].Radiat Environ Biophys,1997,36:59-66.
[11] SELLNER S.Simulations,optimizations and microdosimetric measurements of beam quality for heavy-ion tumor therapy[J].CMES-Computer Modeling in Engineering & Sciences,2013,95(3):177-204.
[12] IVANCHENKO V,INCERTI S,FRANCIS Z,et al.Combination of electromagnetic physics processes for microdosimetry in liquid water with the Geant4 Monte Carlo simulation toolkit[J].Nuclear Instruments and Methods in Physics Research B,2012,273:95-97.
[13] BURIGO L,PSHENICHNOV I,MISHUSTIN I,et al.Microdosimetry of radiation field from a therapeutic 12C beam in water:A study with Geant4 toolkit[J].Nuclear Instruments and Methods in Physics Research B,2013,310:37-53.
[14] KANAI T,FURUSAWA Y,FUKUTSU K,et al.Irradiation of mixed beam and design of spread-out Bragg peak for heavy-ion radiotherapy[J].Radiation Research,1997,147(1):78-84.
[15] KASE Y,KANAI T,MATSUMOTO Y,et al.Microdosimetric measurements and estimation of human cell survival for heavy-ion beams[J].Radiation Research,2006,166(4):629-638.
[16] KASE Y,KANAI T,SAKAMA M,et al.Microdosimetric approach to NIRS-defined biological dose measurement for carbon-ion treatment beam[J].Journal of Radiation Research,2011,52(1):59-68.
[17] GALER S,SHIPLEY D,PALMANS H,et al.Monte Carlo simulation of a TEPC for microdosimetry of carbon ions[J].Radiation Physics and Chemistry,2017,140:412-418.