联影直线加速器新型全碳素纤维治疗床对放疗剂量的影响
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摘要
目的:研究联影直线加速器新型全碳素纤维床床板对放疗剂量的影响。方法:将固体水分别置于治疗床中间(offset=0 cm)、右侧(offset=+10 cm)以及左侧(offset=-10 cm),改变机臂角度,让高能X射线从不同角度穿透治疗床,计算出相对应的衰减因子。结果:对于6 MV的X射线,治疗床板中间处的衰减因子范围是0.043 8~0.085 0,在115°时衰减因子最大;右侧位置的衰减因子范围是0.044 1~0.127 2,在110°时衰减因子最大;左侧位置的衰减因子范围是0.043 2~0.093 1,在110°时衰减因子最大。在180°~130°区间时,治疗床中间、右侧和左侧位置的衰减因子之间的差异较小,且右侧衰减因子高于中间和左侧处。结论:不同的机架角度,在联影直线加速器新型全碳素纤维治疗床床板上不同的位置,对X射线的衰减程度不同。治疗床右侧位置在130°~110°区间对剂量的衰减高于中间和左侧,且在110°时衰减最大,在设计患者后斜野计划时应该尽量避开对剂量衰减程度大的角度。
Objective To investigate the effects of a new carbon fiber couch of linear accelerator from Shanghai United Imaging Healthcare Co.,Ltd on the radiotherapy dose.Methods The solid water phantom were placed in the middle(offset=0 cm),the right(offset=+10 cm) and the left(offset=-10 cm) of the treatment couch.The angle of gantry was changed to make the highenergy X-ray penetrate the treatment couch from different angles,and the corresponding attenuation factors of X-ray were calculated.Results The attenuation factors for 6 MV X-ray were 0.043 8-0.085 0 at the middle of the treatment couch,with a maximum attenuation factor at 115°;0.044 1-0.127 2 at the right side of the treatment couch,with a maximum attenuation factor at 110°;0.043 2-0.093 1 at the left side of the treatment couch,with a maximum attenuation factor at 110°.When the gantry angle was 180°-130°,the differences among the attenuation factors at the middle,the right and the left of the treatment couch were trivial,but the attenuation factor was higher at the right than at the middle and the left.Conclusion The attenuation of the new carbon fiber treatment couch of linear accelerator from Shanghai United Imaging Healthcare Co.,Ltd varies at different positions with different angles of gantry.When the gantry angle was 130°-110°,the dose attenuation is higher at the right side of the treatment couch that at the middle and the left,and the maximum is at 110°.Those angles causing larger dose attenuations should be avoided in oblique field plan.
Objective To investigate the effects of a new carbon fiber couch of linear accelerator from Shanghai United Imaging Healthcare Co.,Ltd on the radiotherapy dose.Methods The solid water phantom were placed in the middle(offset=0 cm),the right(offset=+10 cm) and the left(offset=-10 cm) of the treatment couch.The angle of gantry was changed to make the highenergy X-ray penetrate the treatment couch from different angles,and the corresponding attenuation factors of X-ray were calculated.Results The attenuation factors for 6 MV X-ray were 0.043 8-0.085 0 at the middle of the treatment couch,with a maximum attenuation factor at 115°;0.044 1-0.127 2 at the right side of the treatment couch,with a maximum attenuation factor at 110°;0.043 2-0.093 1 at the left side of the treatment couch,with a maximum attenuation factor at 110°.When the gantry angle was 180°-130°,the differences among the attenuation factors at the middle,the right and the left of the treatment couch were trivial,but the attenuation factor was higher at the right than at the middle and the left.Conclusion The attenuation of the new carbon fiber treatment couch of linear accelerator from Shanghai United Imaging Healthcare Co.,Ltd varies at different positions with different angles of gantry.When the gantry angle was 130°-110°,the dose attenuation is higher at the right side of the treatment couch that at the middle and the left,and the maximum is at 110°.Those angles causing larger dose attenuations should be avoided in oblique field plan.
引文
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[14]MCCORMACK S,DIFFEY J,MORGAN A.The effect of gantry angle on megavoltage photon beam attenuation by a carbon fiber couch insert[J].Med Phys,2005,32(2):483-487.
[15]NJEH C F,RAINES T W,SAUNDERS M W.Determination of the photon beam attenuation by the Brainlab imaging couch:angular and field size dependence[J].J App Clin Med Phys,2009,10(3):2979.
[16]PULLIAM K B,HOWELL R M,FOLLOWILL D,et al.The clinical impact of the couch top and rails on IMRT and arc therapy[J].Phys Med Biol,2011,56(23):7435.
[17]甘家应,胡银祥,洪卫,等.Elekta直线加速器全碳纤维六维治疗床床板对后斜野放疗剂量的影响[J].中国肿瘤,2010,19(8):511-513.GAN J Y,HU Y X,HONG W,et al.The effect of the six dimensional whole carbon fiber bed board of Elekta linear accelerator on the radiation dose of posterior oblique field[J].China Cancer,2010,19(8):511-513.
[18]张西志,李军,汪步海,等.医用直线加速器治疗床对放疗剂量影响的研究[J].生物医学工程学进展,2008,29(3):161-163.ZHANG X Z,LI J,WANG B H,et al.Research of effect for medical linear accelerator treatment table on radiotherapy dosimetry[J].Progress in Biomedical Engineering,2008,29(3):161-163.
[19]DUGGAR W N,NGUYEN A,STANFORD J,et al.Modeling treatment couches in the Pinnacle treatment planning system:especially important for arc therapy[J].OJAA Med Dos,2016,41(1):34.
[20]CHYOU T Y,LORENZ F.Couch modeling for volumetric modulated arc therapy(VMAT)[J].Austral Phys Eng Sci Med,2017,40(2):1-10.
[21]ZHANG R,BAI W,FLECKENSTEIN J.SU-E-T-650:quantification and modeling of the dosimetric impact of the IBEAM Evo Treatment Couchtop EP(Elekta)in VMAT[J].Med Phys,2015,42(6 Part 22):3486.
[2]HUFTON A P,RUSSELL J G.The use of carbon fibre material in table tops,cassette fronts and grid covers:magnitude of possible dose reduction[J].Br J Radiol,1986,59(698):157-163.
[3]COCHRAN B E.The effect of treatment couches on delivered dose during radiotherapy treatments[D].San Diego:San Diego State University,2012.
[4]SHEYKHOO A,ABDOLLAHI S,HADIZADEH YAZDI M H,et al.Effects of Siemens TT-D carbon fiber table top on beam attenuation,and build up region of 6 MV photon beam[J].Rep Pract Oncol Radiot,2017,22(1):19.
[5]OLCH A J,GERIG L,LI H,et al.Dosimetric effects caused by couch tops and immobilization devices:report of AAPM Task Group 176[J].Med Phys,2014,41(6):061501.
[6]YU C Y,CHOU W T,LIAO Y J,et al.Impact of radiation attenuation by a carbon fiber couch on patient dose verification[J].Sci Rep,2017,7:43336.
[7]MUNJAL R K,NEGI P S,BABU A G,et al.Impact of 6 MV photon beam attenuation by carbon fiber couch and immobilization devices in IMRT planning and dose delivery[J].J Med Phys,2006,31(2):67.
[8]MEYDANCI T P,KEMIKLER G.Effect of a carbon fiber tabletop on the surface dose and attenuation for high-energy photon beams[J].Rad Med,2008,26(9):539.
[9]SEPP?L?J K,KULMALA J A.Increased beam attenuation and surface dose by different couch inserts of treatment tables used in megavoltage radiotherapy[J].J App Clin Med Phys,2011,12(4):3554.
[10]胡逸民,张红志,戴建荣,等.肿瘤放射物理学[M].北京:原子能出版社,1999:614-618.HU Y M,ZHANG H Z,DAI J Y,et al.Radiation physical of tumour[M].Beijing:Nuclear Energy Publishing House,1999:614-618.
[11]MYINT W K,NIEDBALA M,WILKINS D,et al.Investigating treatment dose error due to beam attenuation by a carbon fiber tabletop[J].J App Clin Med Phys,2006,7(3):21.
[12]HAYASHI N,SHIBAMOTO Y,OBATA Y,et al.Megavoltage photon beam attenuation by carbon fiber couch tops and its prediction using correction factors[J].J Radiol Res,2010,51(4):455-463.
[13]花威,李军,陈婷婷,等.Varian直线加速器全碳纤维治疗床对放疗剂量的影响[J].医疗卫生装备,2012,33(7):108-109.HUA W,LI J,CHEN T T,et al.Effect of whole carbon fiber couch of Varian linear accelerator on radiotherapy dose[J].Chinese Medical Equipment Journal,2012,33(7):108-109.
[14]MCCORMACK S,DIFFEY J,MORGAN A.The effect of gantry angle on megavoltage photon beam attenuation by a carbon fiber couch insert[J].Med Phys,2005,32(2):483-487.
[15]NJEH C F,RAINES T W,SAUNDERS M W.Determination of the photon beam attenuation by the Brainlab imaging couch:angular and field size dependence[J].J App Clin Med Phys,2009,10(3):2979.
[16]PULLIAM K B,HOWELL R M,FOLLOWILL D,et al.The clinical impact of the couch top and rails on IMRT and arc therapy[J].Phys Med Biol,2011,56(23):7435.
[17]甘家应,胡银祥,洪卫,等.Elekta直线加速器全碳纤维六维治疗床床板对后斜野放疗剂量的影响[J].中国肿瘤,2010,19(8):511-513.GAN J Y,HU Y X,HONG W,et al.The effect of the six dimensional whole carbon fiber bed board of Elekta linear accelerator on the radiation dose of posterior oblique field[J].China Cancer,2010,19(8):511-513.
[18]张西志,李军,汪步海,等.医用直线加速器治疗床对放疗剂量影响的研究[J].生物医学工程学进展,2008,29(3):161-163.ZHANG X Z,LI J,WANG B H,et al.Research of effect for medical linear accelerator treatment table on radiotherapy dosimetry[J].Progress in Biomedical Engineering,2008,29(3):161-163.
[19]DUGGAR W N,NGUYEN A,STANFORD J,et al.Modeling treatment couches in the Pinnacle treatment planning system:especially important for arc therapy[J].OJAA Med Dos,2016,41(1):34.
[20]CHYOU T Y,LORENZ F.Couch modeling for volumetric modulated arc therapy(VMAT)[J].Austral Phys Eng Sci Med,2017,40(2):1-10.
[21]ZHANG R,BAI W,FLECKENSTEIN J.SU-E-T-650:quantification and modeling of the dosimetric impact of the IBEAM Evo Treatment Couchtop EP(Elekta)in VMAT[J].Med Phys,2015,42(6 Part 22):3486.