二维电离室矩阵在调强放射治疗中的剂量验证

目的:对逆向调强计划进行剂量学验证,保证IMRT计划临床实施的正确性。方法:利用ELEKTA precise直线加速器6MV X线,对pinnacle治疗计划系统设计的调强治疗计划。采用PTW公司的729二维电离室矩阵进行平面剂量的验证。结果:平面剂量验证采用Gamma分析(3%/3mm),结果是计划的测量点通过率均＞95%。结论:实际测量的剂量分布与计划计算的剂量分布符合的相当理想,可用于临床治疗。     

虚拟楔形板与物理楔形板角度和因子的比较观察

一般认为虚拟楔形板比物理楔形板具有以下优势：①防止射线硬化;②免装卸,减轻工作人员劳动强度;③可实现15°-60°任意角度;④可实现大野照射;⑤楔形因子为1,剂量计算更简便,机器损耗更小[1];⑥在不加楔形板的一侧没有剂量分布的倾斜[2]。     

Seven29TM二维电离室矩阵剂量学的评价

目的 对Seven29TM二维电离室矩阵的剂量学性能进行评价.方法 利用同体水、IBADose 1剂量仪和RITl 13胶片剂量分析系统,对Seven29TM二维电离室矩阵进行了刻度,对其在固体水中绝对剂量和相对剂量的测量精度进行了检测与验证.同时探讨了Seven29TM二维电离宅矩阵的剂量线性和能最响应.结果 固体水是水的理想等效模体.Seven29TM二维电离窒矩阵在同体水中的刻度因子为1.007,绝对剂量的测量误差<2.1%,相对剂虽测量误差<3.8%.Seven29TM二维电离室矩阵剂量线性误差<0.2%,能昔响应误差<1.2%.结论 Seven29TM二维电离事矩阵在放疗中具有很好的剂量学特性,是开展调强放疗技术的有力工具.     

西门子加速器虚拟楔形板物理参数的剂量学验证

目的　探讨虚拟楔形板楔形角的验证 ;楔形因子与射线能量、照射野尺寸和楔形角大小之间的关系 ;虚拟楔形野、物理楔形野和平野百分深度剂量之间的关系。方法　对西门子公司Meva tronM加速器 6MV、Primus加速器 8、18MV 3种能量X射线 ,用RFA PLUS三维水箱、RK指形电离室分别测量其 15°、30°、45°和 6 0°虚拟楔形板的楔形角和不同大小照射野的楔形因子 ;用FDM 30 0黑度计、KodakXV 2检验胶片测量 6MVX射线 30°虚拟楔形野、物理楔形野和平野的百分深度剂量 ,归一到最大剂量点并进行比较。结果　 4点法测得的虚拟楔形角与设定值有良好的一致性。不论射线能量、照射野大小和楔形角大小 ,虚拟楔形板楔形因子总是约等于 1,最大偏离为 0 .0 31;对于特定能量和照射野 ,大楔形角楔形因子较小楔形角略大 ;对于特定能量和楔形角 ,大野楔形因子较小野略大 ;虚拟楔形野深度剂量曲线非常接近平野 ,两者仅有很细微的差别。结论　 4点法测量虚拟楔形板楔形角可作为日常质量保证手段。虚拟楔形野较物理楔形野治疗不仅简单易行 ,更可以节省加速器出束量。虚拟楔形野与平野的深度剂量曲线的一致性简化了治疗计划或者提高了楔形野实际治疗剂量精度。     

二维电离室矩阵实时验证VMAT剂量价值研究

目的 探讨利用二维电离室矩阵进行VMAT患者透射剂量实时验证的临床价值。方法 将二维电离室矩阵面板粘贴固定在加速器EPID探测面板上,源到EPID探测面板距离为140 cm。电离室矩阵面板上加8 mm的RW3固体水以提高信躁比。选取食管癌、前列腺癌、肝癌患者计划,在圆柱形Cheese模体上照射测量5次,研究患者计划在模体中剂量验证的可行性与准确性。患者每次治疗时进行实时测量,第1次测量结果作为参考剂量,利用γ分析比较分次间剂量误差。结果采用3%3 mm标准,Cheese模体VMAT计划的γ通过率为98%左右,食管癌、前列腺癌和肝癌患者实时照射γ通过率分别约为92%、92%和94%。整个治疗过程中各分次的γ通过率都在90%以上。     

用二维电离室阵列对螺旋断层治疗的调强计划进行剂量验证

目的 研究采用二维电离室阵列对螺旋断层治疗(HT)的调强计划实施剂量验证的可行性,寻求建立一套临床上针对该条件下患者治疗更为有效的剂量验证方法 .方法 采用IBA公司I'mRT MatriXX二维电离室阵列及其相配套MULTICube等效同体水模体对10例患者HT的调强计划实施验证.分别对二维电离室阵列实行冠状及纵向位测量,并获取模体中阵列轴平面和纵断面剂量分布.通过HT系统兆伏级CT图像实现模体精确配准及校正,以确保二维电离室阵列摆位准确性.束流照射后将二维阵列剂量测量平面分布与HT计划系统模体计划中计算平面结果 进行比较,定性或定量分析其绝对剂最及相对剂量验证情况.探讨其不同位置摆放来实现其测量方法 的可行性.结果 定性或定量分析所测量与计算绝对剂量点及相对剂量分布的结果 均显示出了较好一致性,点绝对测量与计算剂量偏差保持在±3%以内.MatrXX阵列测量的相对剂量分布与治疗计划系统模体中计算平面相比较,采用了Gamma法(3 mm或3%)进行2 mm栅格精度分析,γ≤1像素点平均通过率分别为97.76%、96.83%.结论 MatriXX二维电离室阵列可较好地进行绝对剂量及相对剂量测量,能较好地实现调强计划的剂量验证.     

用二维电离室阵列对螺旋断层治疗的调强计划进行剂量验证

Objective To investigate the feasibility of dose verification of intensity modulated (IM) planning of helical tomotherapy (HT) using two-dimensional ion chamber array (2DICA),and develop an efficient way to validate the dose delivered under the parameters mirroring those during the treatment. Meth-ods A 2DICA,I'mRT MatriXX and MULTICube equivalent solid water phantom from IBA company were used to verify the dose distribution of 10 IM planning. The combined phantom was set up to measure the dose distributions on coronal and sagittal surface. The precise setup of phantom was guided by HTMVCT images. After the irradiation, the measured dose distributions on the coronal and sngittal plane were compared with those calculated by the IM planning system for verification. The results were evaluated and the feasibility of the different measuring methods was studied. Results The dose distribution measured by the MatriXX 2DICA was well consistent with that calculated by the treatment planning system. The errors between the measured dose and predicted dose in the selected points were within ±3%. In the comparison of the pixel-segmented ionization chamber versus treatment planning system using the 3 mm/3% γ criteria, the passing ratio of pixels with γ parameter ≤1 was 97.76% and 96.83%, respectively. Conclusions MatriXX is a-ble to measure the absolute and relative dose distributions simultaneously,which can be used for dose verifi-cation of IM planning.     

基于OCTAVIUS 1500电离室矩阵的近距离放疗相对剂量分布验证

目的 通过OCTAVIUS 1500电离室矩阵对高剂量率近距离放疗剂量分布进行可行性验证,探讨其剂量分布的验证方法.方法 首先利用井型电离室对放射源的活度进行标定,然后对放有施源器的电离室矩阵进行计算机断层扫描,图像传至放疗计划系统进行计划设计,最后利用OCTAVIUS 1500电离室矩阵对剂量分布进行验证.结果 本研...     

用二维电离室阵列对螺旋断层治疗的调强计划进行剂量验证

Objective To investigate the feasibility of dose verification of intensity modulated (IM) planning of helical tomotherapy (HT) using two-dimensional ion chamber array (2DICA),and develop an efficient way to validate the dose delivered under the parameters mirroring those during the treatment. Meth-ods A 2DICA,I'mRT MatriXX and MULTICube equivalent solid water phantom from IBA company were used to verify the dose distribution of 10 IM planning. The combined phantom was set up to measure the dose distributions on coronal and sagittal surface. The precise setup of phantom was guided by HTMVCT images. After the irradiation, the measured dose distributions on the coronal and sngittal plane were compared with those calculated by the IM planning system for verification. The results were evaluated and the feasibility of the different measuring methods was studied. Results The dose distribution measured by the MatriXX 2DICA was well consistent with that calculated by the treatment planning system. The errors between the measured dose and predicted dose in the selected points were within ±3%. In the comparison of the pixel-segmented ionization chamber versus treatment planning system using the 3 mm/3% γ criteria, the passing ratio of pixels with γ parameter ≤1 was 97.76% and 96.83%, respectively. Conclusions MatriXX is a-ble to measure the absolute and relative dose distributions simultaneously,which can be used for dose verifi-cation of IM planning.     

用二维电离室阵列对螺旋断层治疗的调强计划进行剂量验证

Objective To investigate the feasibility of dose verification of intensity modulated (IM) planning of helical tomotherapy (HT) using two-dimensional ion chamber array (2DICA),and develop an efficient way to validate the dose delivered under the parameters mirroring those during the treatment. Meth-ods A 2DICA,I'mRT MatriXX and MULTICube equivalent solid water phantom from IBA company were used to verify the dose distribution of 10 IM planning. The combined phantom was set up to measure the dose distributions on coronal and sagittal surface. The precise setup of phantom was guided by HTMVCT images. After the irradiation, the measured dose distributions on the coronal and sngittal plane were compared with those calculated by the IM planning system for verification. The results were evaluated and the feasibility of the different measuring methods was studied. Results The dose distribution measured by the MatriXX 2DICA was well consistent with that calculated by the treatment planning system. The errors between the measured dose and predicted dose in the selected points were within ±3%. In the comparison of the pixel-segmented ionization chamber versus treatment planning system using the 3 mm/3% γ criteria, the passing ratio of pixels with γ parameter ≤1 was 97.76% and 96.83%, respectively. Conclusions MatriXX is a-ble to measure the absolute and relative dose distributions simultaneously,which can be used for dose verifi-cation of IM planning.     

用二维电离室矩阵验证多叶准直器叶片到位精度

目的用二维电离室矩阵验证多叶准直器(MLC)叶片的到位精度。方法使用PTW公司的Seven29~(TM)二维电离室矩阵对医科达公司的Precise加速器的MLC进行测量。先测出叶片到位的边缘函数作为基准,再根据测量值和标准值的差异评价叶片的位置精度。结果MLC叶片到位精度可达到±0．1 mm。结论使用二维电离室矩阵验证多叶准直器到位精度方法简单易行,结果可靠。     

二维电离室阵列与EDR2胶片在螺旋断层治疗计划剂量验证中的应用研究

目的 比较EDR2胶片与二维电离室阵列在螺旋断层治疗(HT)计划质量保证过程中的剂量学特性,并分析测量方法间的可能差异.方法 采用IBA公司I′mRT MatriXX二维电离室阵列其相配套MULTICube等效固体水模体,同时夹放EDR2胶片对15例患者HT计划实施剂量学验证,分别实行轴位和纵向摆位测量以获取模体冠、矢状面剂量分布.照后将两种方法所测得的剂量分布与其对应模体计划中计算结果进行比对,以γ分析法(3 mm/3%)评估验证情况及实施效率.结果 15例患者冠状面、矢状面二维电离室阵列和EDR2胶片测量的γ≤1平均通过率分别为97.00%±1.56%和95.98%±2.52%(t=-2.22,P=0.043)、98.28%±1.55%和95.42%±1.99%(t=0.75,P=0.464);其中>90%、>95%通过率比例分别为93.3%、66.7%.两种方法测量所得剂量分布与计算结果在相同平面的几何分布均有较好的符合度,且亦存在一定相关性(r=0.14,P=0.001).结论 日常HT质量保证中二维电离室阵列可有效替代胶片和电离室测量,而胶片验证作为"金标准"为定期相互比对提供了可能.

Abstract：

Objective The aim of this work is to compare the performances of EDR2 film dosimetry with two-dimensional ion chamber array (2DICA) in quality assurance (QA) procedures and to investigate the origin of possible discrepancies between the two methods.Methods A 2DICA, I′mRT MatriXX and MULTICube equivalent solid water phantom from IBA Company were used to verify the dose distribution of 15 tomotherapy plan cases.The combined phantom which includes EDR2 film on the array was set up to measure the dose distribution from coronal and sagittal orientations.After the irradiation, the dose distributions of 2DICA and film were compared with those calculated in the planning system for verification.The results and efficiency were evaluated independently in the two methods.Results The mean number of points satifying γ parameter ≤1 in the coronal and sagittal planes was 97.00%±1.56%& 95.98%±2.52%(t=-2.22,P=0.043) and 98.28%±1.55%& 95.42%±1.99%(t=0.75,P=0.464) of the 15 cases respectively for 2DICA and EDR2 film.The ratio of more than 90% and 95% were 93.3% and 66.7%.The results we presented show a very good agreement between the two methods when used to assess the dose distribution between calculated and measured doses,and a certain degree of correlation (r=0.14,P=0.001).Conclusions The 2DICA may effectively replace both film and ion chamber dosimetry in routine IMRT QA.The good agreement between 2DICA and EDR2 film may give a possible check regularly just as a gold standard.     

用二维电离室阵列对螺旋断层治疗的调强计划进行剂量验证

Objective To investigate the feasibility of dose verification of intensity modulated (IM) planning of helical tomotherapy (HT) using two-dimensional ion chamber array (2DICA),and develop an efficient way to validate the dose delivered under the parameters mirroring those during the treatment. Meth-ods A 2DICA,I'mRT MatriXX and MULTICube equivalent solid water phantom from IBA company were used to verify the dose distribution of 10 IM planning. The combined phantom was set up to measure the dose distributions on coronal and sagittal surface. The precise setup of phantom was guided by HTMVCT images. After the irradiation, the measured dose distributions on the coronal and sngittal plane were compared with those calculated by the IM planning system for verification. The results were evaluated and the feasibility of the different measuring methods was studied. Results The dose distribution measured by the MatriXX 2DICA was well consistent with that calculated by the treatment planning system. The errors between the measured dose and predicted dose in the selected points were within ±3%. In the comparison of the pixel-segmented ionization chamber versus treatment planning system using the 3 mm/3% γ criteria, the passing ratio of pixels with γ parameter ≤1 was 97.76% and 96.83%, respectively. Conclusions MatriXX is a-ble to measure the absolute and relative dose distributions simultaneously,which can be used for dose verifi-cation of IM planning.     

用二维电离室阵列对螺旋断层治疗的调强计划进行剂量验证

Objective To investigate the feasibility of dose verification of intensity modulated (IM) planning of helical tomotherapy (HT) using two-dimensional ion chamber array (2DICA),and develop an efficient way to validate the dose delivered under the parameters mirroring those during the treatment. Meth-ods A 2DICA,I'mRT MatriXX and MULTICube equivalent solid water phantom from IBA company were used to verify the dose distribution of 10 IM planning. The combined phantom was set up to measure the dose distributions on coronal and sagittal surface. The precise setup of phantom was guided by HTMVCT images. After the irradiation, the measured dose distributions on the coronal and sngittal plane were compared with those calculated by the IM planning system for verification. The results were evaluated and the feasibility of the different measuring methods was studied. Results The dose distribution measured by the MatriXX 2DICA was well consistent with that calculated by the treatment planning system. The errors between the measured dose and predicted dose in the selected points were within ±3%. In the comparison of the pixel-segmented ionization chamber versus treatment planning system using the 3 mm/3% γ criteria, the passing ratio of pixels with γ parameter ≤1 was 97.76% and 96.83%, respectively. Conclusions MatriXX is a-ble to measure the absolute and relative dose distributions simultaneously,which can be used for dose verifi-cation of IM planning.     

用二维电离室阵列对螺旋断层治疗的调强计划进行剂量验证

Objective To investigate the feasibility of dose verification of intensity modulated (IM) planning of helical tomotherapy (HT) using two-dimensional ion chamber array (2DICA),and develop an efficient way to validate the dose delivered under the parameters mirroring those during the treatment. Meth-ods A 2DICA,I'mRT MatriXX and MULTICube equivalent solid water phantom from IBA company were used to verify the dose distribution of 10 IM planning. The combined phantom was set up to measure the dose distributions on coronal and sagittal surface. The precise setup of phantom was guided by HTMVCT images. After the irradiation, the measured dose distributions on the coronal and sngittal plane were compared with those calculated by the IM planning system for verification. The results were evaluated and the feasibility of the different measuring methods was studied. Results The dose distribution measured by the MatriXX 2DICA was well consistent with that calculated by the treatment planning system. The errors between the measured dose and predicted dose in the selected points were within ±3%. In the comparison of the pixel-segmented ionization chamber versus treatment planning system using the 3 mm/3% γ criteria, the passing ratio of pixels with γ parameter ≤1 was 97.76% and 96.83%, respectively. Conclusions MatriXX is a-ble to measure the absolute and relative dose distributions simultaneously,which can be used for dose verifi-cation of IM planning.