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。     

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.     

利用二维电离室矩阵验证鼻咽癌调强放射治疗的剂量分布

[目的]比较实际受照的剂量分布与计划的剂量分布,评价鼻咽癌调强放射治疗（IMRT）计划临床治疗的准确性。[方法]选取将做调强放射治疗的8例鼻咽癌患者,做好调强放射治疗计划,并将计划移植到二维电离室矩阵,生成验证计划,在加速器上进行模拟治疗,利用二维电离室矩阵进行测量,将测得的数据和原计划的数据进行比较和分析。[结果]经过gamma分析（按3mm和5%的误差标准）,98.2%的射野通过率超过95%,平均通过率为97.13%±1.27%,只有一个野的通过率小于95%为94.66%。[结论]实际测量的剂量分布与计划计算的剂量分布符合的较理想,可用于临床治疗。     

调强放射治疗的物理剂量验证

目的：检测调强适形放射治疗（Intensity modulatet radiation therapy,IMRT)的剂量误差,探索IMRT的质量控制和质量保证的措施和方法。方法：（1）用体模治疗计划移植的方法对43例IMRT治疗计划的照射区以电离室作实际物理剂量测量,以验证治疗计划系统剂量计算的准确性,照射设备的可靠性和稳定性,修正IMRT治疗剂量误差和确定其剂量精度范围。（2）选取计划照射区内剂量梯度变化较大处进行重复摆位测量剂量,推算和验证由于摆位误差可能造成的剂量误差。结果：（1）与计划剂量比较,实际测量剂量的相对误差范围为-0.74%-4.98%并近似正态分布,平均误差为2.38%。标准差为1.39%,标准误为0.21%。全部43例的剂量误差均在5%以内。（2）实际测量的剂量梯度变化与计划剂量梯度一致,全部计划中的最大梯度值为15%/mm。在该处重复摆位测量的最在与最小值的相对差别为1.97%。结论：用体模计划移植测量方法能有效检验IMRT计划计算和执行的误差,可作为每个病人治疗前的剂量验证常规方法;IMRT治疗精度的保证需要优于1mm的额外精确摆位。     

利用二维电离室矩阵验证食管癌调强放疗的剂量分布

目的比较实际受照剂量分布与计划剂量分布,评价食管癌调强放射治疗计划处方实施的准确性。方法选取135例食管癌患者,采用束流调强放射治疗,并将其中99例治疗计划移植到二维电离室矩阵和验证模体中,生成验证计划,在加速器上进行模拟治疗。利用二维电离室矩阵进行测量,将测得剂量数据和计划剂量数据进行比较和分析。结果经过Gamma分析（按3％／3mm的误差标准）,82．8％的计划验证通过率≥90．0％,平均通过率为94．8％,标准误差为0．6％。结论实际测量剂量分布与计划剂量分布符合情况基本理想,部分治疗计划需进一步调试修正直至验证通过后才可用于临床治疗。     

调强适形放射治疗的剂量学验证

理论上 ,调强适形放射治疗 (ｉｎｔｅｎｓｉｔｙｍｏｄｕｌａｔｅｄｒａｄｉａｔｉｏｎｔｈｅｒａｐｙ,ＩＭＲＴ)与常规放射治疗相比较的优势 ,一是提高了靶区的剂量 ,二是减少了周围正常组织或关键器官的照射剂量。ＩＭＲＴ技术与常规放射治疗技术相比远为复杂 ,逆向计划的优化算法在某些方面还不成熟 ,放射治疗中还存在众多不确定因素 ,ＩＭＲＴ实施后的剂量准确与否直接关系到治疗的最终结果。虽然远期的治疗结果是检验ＩＭＲＴ计划乃至剂量准确性的金标准 ,但遗憾的是 ,至今还没有关于该技术治疗恶性肿瘤长期结果的报道。因此 ,治疗前的…     

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.     

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.     

利用0.13cc电离室对头颈部肿瘤调强放疗计划的剂量学验证

目的:利用0.13cc电离室对头颈部肿瘤调强适形放射治疗(IMRT)计划进行剂量学验证.方法:将20例头颈部肿瘤患者的IMRT计划分别移植到经过CT扫描的调强体模,生成验证计划,将0.13cc电离室放置到调强体模中在加速器下执行验证计划,在治疗计划系统中算出电离室所在区域的吸收剂量为计划剂量,按验证计划照射测量到的电离室吸收剂量为实测剂量,将二者进行比较得出误差.相对误差=(计划剂量-实测剂量)/实测剂量.百分误差超过±5％,说明计划在执行中剂量误差过大,计划需要修正.结果:20例患者中有17例患者验证的误差在±5％以内,表明计划通过;有3例患者误差超过±5％以内,计划需重新修改,计划通过率为85％.结论:剂量学验证确定IMRT治疗剂量的置信度,保证治疗计划的准确实施,提供了临床评价治疗计划的依据.     

用放射性铬胶片进行调强放疗剂量验证的研究

目的研究新型放射性铬胶片(RCF)的剂量响应特性,探讨其用于个体化调强放疗(IMRT)平面剂量验证的临床应用方法和剂量精度,简化传统胶片剂量测量系统的质控过程,建立更可靠易行的调强放疗剂量分布验证系统。方法采用阶梯式剂量-光密度刻度方法校正RCF和传统胶片(EDR2),比较两者剂量学特性与测量精度差别及过程的质控要求。采用模体内剂量实测方法,以RCF和EDR2胶片分别测量验证IMRT计划在同一平面的剂量分布,并与治疗计划系统计算的剂量注量分布、离轴剂量分布曲线、等剂量曲线等进行比较,评价RCF用于IMRT剂量分布验证的效果。结果在0～500 cGy外照射剂量范围内,RCF/VXR-16和EDR2/VXR-16胶片剂量系统的测量离散度均不超过0.70%,平均不确定度分别为0.37%和0.68%。IMRT剂量分布验证的RCF测量和严格执行冲片质控的EDR2胶片测量结果十分相近,两者在模体内同一平面与计划计算的最大离轴剂量偏差分别为3.1%和3.6%,相同DTA与△D设定值的γ像素符合率分别为94.28%和92.92%。结论RCF的剂量系统应用于临床个体化IMRT平面剂量验证,有较高可靠性和可信度,且操作和质控过程与传统剂量胶片相比大大简化,可以在临床推广应用。     

鼻咽癌动态调强放疗计划的剂量学验证

目的建立鼻咽癌动态调强放疗计划的剂量学验证方法。方法对80例鼻咽癌动态调强放疗计划分别进行3个项目的剂量验证一是用电离室在人体等效模体中测量靶区参考点的绝对剂量,二是使用二维电离室矩阵测量调强计划每个射野的剂量强度分布,三是使用慢感光胶片竖插在模体内,测量调强计划横断面的剂量分布。结果92.5%计划靶区参考点的绝对剂量误差小于5%,在改用体积较小的电离室和调整机架角度避开固定装置重新制定计划后,所有计划靶区参考点的绝对剂量误差也都小于5%。有88.1%的照射野剂量分布误差小于3%。结论为了得到更加真实的测量结果,建议所有测量,尤其是绝对剂量测量都在计划实际机架角度下进行。利用二维电离室矩阵可定量分析照射野剂量分布误差,并且省时省力,有利于验证工作的常规化。胶片法验证由于费时费力且误差较大已趋于淘汰。对于动态调强计划,模体计划各个射野的机器跳数(MU)应与实际计划相同,这样才能得到更加真实的测量结果。     

A comparison of the quality assurance of four dosimetric tools for intensity modulated radiation therapy

Background

This study was designed to compare the quality assurance (QA) results of four dosimetric tools used for intensity modulated radiation therapy (IMRT) and to suggest universal criteria for the passing rate in QA, irrespective of the dosimetric tool used.

Materials and methods.

Thirty fields of IMRT plans from five patients were selected, followed by irradiation onto radiochromic film, a diode array (Mapcheck), an ion chamber array (MatriXX) and an electronic portal imaging device (EPID) for patient-specific QA. The measured doses from the four dosimetric tools were compared with the dose calculated by the treatment planning system. The passing rates of the four dosimetric tools were calculated using the gamma index method, using as criteria a dose difference of 3% and a distance-to-agreement of 3 mm.

Results

The QA results based on Mapcheck, MatriXX and EPID showed good agreement, with average passing rates of 99.61%, 99.04% and 99.29%, respectively. However, the average passing rate based on film measurement was significantly lower, 95.88%. The average uncertainty (1 standard deviation) of passing rates for 6 intensity modulated fields was around 0.31 for film measurement, larger than those of the other three dosimetric tools.

Conclusions

QA results and consistencies depend on the choice of dosimetric tool. Universal passing rates should depend on the normalization or inter-comparisons of dosimetric tools if more than one dosimetric tool is used for patient specific QA.     

鼻咽癌容积调强旋转放疗和固定野适形调强放疗的剂量学对比

目的：对比旋转容积调强技术（RapidArc ）和固定野适形调强放疗（intensity modulated radiation therapy ,IMRT）治疗鼻咽癌剂量学方面的差异,探索不同T 分期从何种技术获益最大。方法：选取60例无远处转移鼻咽癌患者,按鼻咽癌2008分期T 1～2期20例,T 3 期20例,T 4 期20例。使用瓦里安公司Eclipse 系统,每例患者分别制定RapidArc 和固定野IMRT 计划,比较两者靶区覆盖、危机器官剂量、跳数和治疗时间的差别。结果：IMRT 和RapidArc 均能满足临床要求,靶区剂量分布差异无统计学意义（P >0.05）,均匀性和适形性相当。按T 分期分层比较,T 4 期患者RapidArc 组PGTV、PTV 1、PTV 2 的靶区剂量较高（P < 0.05）,PGTV 均匀指数较好（P = 0.059）。 RapidArc 组视神经、晶体、颞叶、腮腺V 20、喉、颞颌关节受照剂量均较低（P < 0.05）。 按T 分期分层比较,脑干剂量T 1～2 期、T 3 期两组比较差异无统计学意义（P > 0.05）,T 4 期患者脑干D 1% 、Dmax剂量RapidArc 组较IMRT 组低（P < 0.05）。RapidArc 和IMRT 相比,治疗跳数节省65% ,治疗时间节省63% 。结论：RapidArc 和9 野IMRT 治疗鼻咽癌均可满足临床要求,Rap?idArc 可明显降低正常器官剂量,缩短治疗时间,减少治疗跳数。对局部早、中期（T 1～3 期）患者,两者有相似的靶区剂量分布,但对局部晚期（T 4 期）患者,RapidArc 更具有将高剂量区集中在靶区而减少正常器官受照剂量的优势。     

鼻咽癌调强放疗的剂量学研究

 【摘要】目的 分析鼻咽癌调强放疗各个靶区和周围正常组织器官的剂量学特点。方法 2005年1月-2006年6月住院的30例初治鼻咽癌进行调强放疗，将鼻咽和颈部的靶体积勾画为鼻咽大体肿瘤体积（GTVnx）、颈部大体肿瘤体积(GTVnd)、临床靶体积1（CTV1）和临床靶体积2(CTV2)，处方剂量分别为70、66、60、60Gy/30F，鼻咽和上颈部靶体积采用IMRT技术照射、下颈部靶体积采用下颈前野常规照射。研究GTV、CTV的最大、最小、平均剂量和颞叶、脑干、脊髓、视神经、晶体、眼球的最大受照剂量及腮腺、颞下颌关节的50%体积受照剂量。结果 GTVnx的最大、最小、平均剂量（均值）分别为79.2、59.5、71.9Gy, GTVnd的最大、最小、平均剂量分别为77.1、63.6、72.1Gy，CTV1、CTV2的最小剂量分别为47.6、49.7Gy，颞叶、脑干、脊髓、视神经、晶体、眼球的最大受照剂量及腮腺、颞下颌关节的50%体积受照剂量63.2、48.6、44.7、59.3、6.9、25.9Gy和34.0、36.3Gy。结论 调强放疗可以使各个靶区得到足够的、均匀的剂量分布，周围正常组织器官得到较好的保护，但是要注意CTV的低剂量区。鼻咽癌调强放疗剂量分布优于常规放疗。     

局部晚期喉癌3DCRT与IMRT放疗计划的剂量学对比

目的 利用ECLIPSE计划系统对局部晚期喉癌适形放疗(3DCRT)和逆向调强适形放疗(IMRT)计划作剂量学比较,评估不同照射方法的优缺点。方法 选择6例病理证实的局部晚期喉癌患者,用ECLIPSE对每例患者分别作出3DCRT和IMRT计划。根据靶区V95%、D5%、D95%、靶区最大值、最小值及平均值和正常组织受量D50、D33、D5、Dmax和Dmean来比较这两种计划剂量学的差异。结果 两种不同计划中的靶区分布中,GTV和GTVnd差别不大,但对于亚临床区CTV和某些正常组织有统计学差异。结论 对局部晚期喉癌原发灶及阳性淋巴结,3DCRT和IMRT计划均有较好覆盖。但在亚临床病灶方面,IMRT比3DCRT包含靶区更好一些,且IMRT减少了腮腺正常组织的照射剂量。     

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.