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宫颈癌术后放疗靶区较大,与膀胱、直肠、股骨头关系密切,为保证放疗的精确性,放疗实施前需要对患者的放疗计划进行严格的剂量验证[1-3]。目前,电离室矩阵由于具有绝对剂量测量准确、可进行剂量叠加等优势,已成为临床上最常用的计划剂量验证工具,配合不同模体(二维和三维模体)及不同验证计划产生方法(所有射野角度归0°验证和实际射野角度验证)可以组合出不同的验证方案[4]。笔者通过分析PTW 729电离室矩阵在宫颈癌术后调强放疗计划中不同验证方法的结果差异,为其计划设计优化和剂量验证提供参考。
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V1、V2、V3验证计划的计划验证通过率分别为(99.72±0.44)%、(94.95±6.13)%、(94.72±6.43)%,评估点数分别为311±50、392±61、391±60。V1的计划验证通过率高于V2,而评估点数低于V2,二者比较差异均有统计学意义(t=2.621、−6.992,均P<0.05)。这说明使用不同的模体验证时获得的结果存在差异。
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由表1可知,与V3验证计划比较,V2的180°和232°射野的单野验证通过率均高,且差异均有统计学意义(均P<0.05),这说明实际射野角度验证及射野角度归0°验证在某些角度获得的射野验证通过率存在差异,实际射野验证的通过率略低。
机架角度 V1 V2 V3 180° 99.16±0.77 96.86±3.79 95.72±3.56a 232° 99.31±0.78 98.50±2.28 92.98±5.04a 284° 98.89±1.93 98.97±1.65 98.24±2.82 326° 99.41±0.84 98.48±2.90 98.70±2.58 28° 98.27±1.53 96.89±4.36 96.58±4.62 80° 99.62±0.61 97.33±4.25 97.18±3.79 130° 99.19±0.64 96.49±4.34 94.32±6.36 注:a表示与V2相比,差异均有统计学意义(t=2.294、4.052,均P<0.05)。V1为利用PTW RW3固体水模体生成二维射野角度归0°验证计划;V2为利用PTW Octavius 4D模体生成二维射野角度归0°验证计划;V3为利用PTW Octavius 4D模体生成二维实际射野角度验证计划 表 1 10例宫颈癌患者术后调强放疗计划的3种二维验证计划 不同机架角度单野验证通过率的比较(
,%)$\bar{x}\pm s $ Table 1. Comparison of different angle single-field verification pass rate in three two-dimensional verification for 10 case of postoperative cervical cancer patients (
, %)$\bar{x}\pm s $ -
V4的计划验证通过率和评估点数分别为(86.91±2.63)%和726 034±61 656。V1、V2、V3的计划验证通过率均高于V4,且差异均有统计学意义(t=17.912、6.645、5.962,均P<0.05);但V4的评估点数明显较高,且差异均有统计学意义(t=−37.244、−37.253、−37.252,均P<0.05)。这说明采用二维和三维验证计划时获得的结果存在差异,且三维验证时观察的评估点数远高于二维验证。
PTW 729电离室矩阵不同验证方法用于宫颈癌术后调强放疗计划验证结果分析
Analysis about the IMRT plan verification results obtained from different verification methods with PTW 729 ionization chamber matrix for postoperative cervical cancer patients
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摘要:
目的 分析PTW 729电离室矩阵不同验证方法用于宫颈癌术后调强放疗计划验证的结果差异。 方法 回顾性分析2020年8至12月于南通大学第二附属医院行宫颈癌术后调强放疗的10例女性患者的放疗资料。患者年龄44~69岁,中位年龄59岁,均采用七野均分方式进行调强放疗计划设计。采用治疗计划系统分别在4.2 cm厚的固体水+电离室矩阵+5.0 cm厚的固体水组成的RW3固体水模体图像上生成二维射野角度归0°验证计划(V1),在PTW Octavius 4D模体图像上生成二维射野角度归0°验证计划(V2)、二维实际射野角度验证计划(V3)和三维实际射野角度验证计划(V4)。在加速器上实测后分析宫颈癌术后调强放疗计划不同验证模体(V1 vs. V2)、二维射野角度归0°和二维实际射野角度验证(V2 vs. V3)、二维和三维验证(V1、V2、V3 vs. V4)的结果差异。计量资料的比较采用配对t检验。 结果 (1)V1的计划验证通过率高于V2[(99.72±0.44)%对(94.95±6.13)%,t=2.621,P<0.05],而评估点数低于V2(311±50对392±61,t=−6.992,P<0.05)。(2)V2的 180°和232°射野的单野验证通过率均高于V3[(96.86±3.79)% 对(95.72±3.56)%,(98.50±2.28)%对(92.98±5.04)%,t=2.294、4.052,均P<0.05 ]。(3)V1、V2、V3的计划验证通过率显著高于V4 [(99.72±0.44)%、(94.95±6.13)%、(94.72±6.43)%对(86.91±2.63)%,t=17.912、6.645、5.962,均P<0.05],而评估点数显著低于V4 (311±50、392±61、391±60对726 034±61 656,t=−37.244、−37.253、−37.252,均P<0.05)。 结论 PTW 729电离室矩阵不同验证方法获得的调强放疗计划验证结果存在一定差异,尤其是180°和232°的单野验证结果。评判宫颈癌术后调强放疗计划是否通过验证需结合所采用的验证方法并对剂量差异区域的评估点进行分析。 Abstract:Objective To analyze the differences of intensity-modulated radiotherapy (IMRT) plan verification results obtained from various verification methods with PTW 729 ionization chamber matrix for postoperative cervical cancer patients. Methods The radiotherapy data of 10 postoperative cervical cancer patients, aged 44–69 years old, with a median age of 59 years old were analyzed retrospectively. The patients were underwent IMRT in the Second Affiliated Hospital of Nantong University from August 2020 to December 2020. The IMRT plan was designed with seven fields. Using the treatment planning system, four verification plans, namely, V1–V4, with different phantoms were designed. Three 2D isocenter plane verification plans (V1−V3) and one 3D stereoscopic verification plan (V4) were designed. In V1, all field angles were converted to 0°, and PTW 729 RW3 solid water was used which composed of 4.2 cm-thick solid water + ionization chamber matrix + 5.0 cm-thick solid water. In V2, all field angles were converted to 0°, and the PTW Octavius 4D phantom was used. The actual angle and the Octavius 4D phantom were used to obtain one-plane verification (V3) and stereoscopic verification (V4). Then, all of the above mentioned four verification plans were actually measured in an accelerator, and the differences of the measurement results between the verification plans in which different verification phantoms were used (V1 vs. V2), between two 2D plans in which all field angles were converted to 0° or actual angle were used (V2 vs. V3), and between 2D and 3D plans(V1, V2, V3 vs. V4), were analyzed with paired t test respectively. Results (1) The plan validation pass rate of V1 was significantly higher than that of V2 ((99.72±0.44)% vs. (94.95±6.13)%, t=2.621, P<0.05). The evaluation point of V1 were lower than that of V2 (311±50 vs. 392±61, t=−6.992, P<0.05). (2) The single-field validation pass rates of 180° and 232° fields in V2 were higher than that in V3 ((96.86±3.79)% vs. (95.72±3.56)%, (98.50±2.28)% vs. (92.98±5.04)%; t=2.294, 4.052; both P<0.05). (3) The plan validation pass rates of V1, V2, and V3 plans were significantly higher than that of V4 ((99.72±0.44)%, (94.95±6.13)%, (94.72±6.43)% vs. (86.91±2.63)%; t=17.912, 6.645, 5.962; all P<0.05). The evaluation points of V1, V2, and V3 were significantly lower than that of V4 (311±50, 392±61, 391±60 vs. 726 034±61 656; t=−37.244, −37.253, −37.252; all P<0.05). Conclusions Differences were found in the verification results of the IMRT plan obtained from different verification methods with PTW 729 ionization chamber matrix, especially the single field verification results for 180° and 232°. Therefore, to judge whether the IMRT plan for postoperative cervical cancer passed the verification, the verification methods and the location of the evaluation point with significant dose difference must be considered. -
表 1 10例宫颈癌患者术后调强放疗计划的3种二维验证计划 不同机架角度单野验证通过率的比较(
,%)$\bar{x}\pm s $ Table 1. Comparison of different angle single-field verification pass rate in three two-dimensional verification for 10 case of postoperative cervical cancer patients (
, %)$\bar{x}\pm s $ 机架角度 V1 V2 V3 180° 99.16±0.77 96.86±3.79 95.72±3.56a 232° 99.31±0.78 98.50±2.28 92.98±5.04a 284° 98.89±1.93 98.97±1.65 98.24±2.82 326° 99.41±0.84 98.48±2.90 98.70±2.58 28° 98.27±1.53 96.89±4.36 96.58±4.62 80° 99.62±0.61 97.33±4.25 97.18±3.79 130° 99.19±0.64 96.49±4.34 94.32±6.36 注:a表示与V2相比,差异均有统计学意义(t=2.294、4.052,均P<0.05)。V1为利用PTW RW3固体水模体生成二维射野角度归0°验证计划;V2为利用PTW Octavius 4D模体生成二维射野角度归0°验证计划;V3为利用PTW Octavius 4D模体生成二维实际射野角度验证计划 -
[1] Miften M, Olch A, Mihailidis D, et al. Tolerance limits and methodologies for IMRT measurement-based verification QA: recommendations of AAPM Task Group No. 218[J]. Med Phys, 2018, 45(4): e53−e83. DOI: 10.1002/mp.12810. [2] Radojcic ĐS, Rajlic D, Casar B, et al. Evaluation of two-dimensional dose distributions for pre-treatment patient-specific IMRT dosimetry[J]. Radiol Oncol, 2018, 52(3): 346−352. DOI: 10.2478/raon-2018-0019. [3] 马晓春, 蔡宏懿, 李冬云, 等. Octavius验证系统用于旋转调强三维剂量验证的研究[J]. 甘肃医药, 2020, 39(9): 791−795. DOI: 10.15975/j.cnki.gsyy.2020.09.008.
Ma XC, Cai HY, Li DY, et al. A study on the application of Octavius verification system to rotational intensity-modulated three-dimensional dose verification[J]. Gansu Med J, 2020, 39(9): 791−795. DOI: 10.15975/j.cnki.gsyy.2020.09.008.[4] Low DA, Moran JM, Dempsey JF, et al. Dosimetry tools and techniques for IMRT[J]. Med Phys, 2011, 38(3): 1313−1338. DOI: 10.1118/1.3514120. [5] Mijnheer BJ, González P, Olaciregui-Ruiz I, et al. Overview of 3-year experience with large-scale electronic portal imaging device-based 3-dimensional transit dosimetry[J]. Pract Radiat Oncol, 2015, 5(6): e679−e687. DOI: 10.1016/j.prro.2015.07.001. [6] 王宁, 陈阿龙. Octavius 4D电离室探头特性及在RapidArc剂量验证中的应用研究[J]. 中国医疗设备, 2019, 34(7): 65−68. DOI: 10.3969/j.issn.1674-1633.2019.07.015.
Wang N, Chen AL. Characteristics and clinical application of the Octavius 4D ionization chamber arrays in dose verification of the RapidArc[J]. China Med Dev, 2019, 34(7): 65−68. DOI: 10.3969/j.issn.1674-1633.2019.07.015.[7] 王勇, 李俊萍, 张玲玲, 等. 不同病种IMRT计划验证通过率差异分析[J]. 中华放射肿瘤学杂志, 2017, 26(1): 50−52. DOI: 10.3760/cma.j.issn.1004-4221.2017.01.011.
Wang Y, Li JP, Zhang LL, et al. The differences among the pass rate of intensity modulated radiation therapy planning in different tumors[J]. Chin J Radiat Oncol, 2017, 26(1): 50−52. DOI: 10.3760/cma.j.issn.1004-4221.2017.01.011.[8] Lv Y, Wang F, Yang L, et al. Intensity-modulated whole pelvic radiotherapy provides effective dosimetric outcomes for cervical cancer treatment with lower toxicities[J]. Cancer Radiother, 2014, 18(8): 745−752. DOI: 10.1016/j.canrad.2014.08.005. [9] 马建华, 李明, 刘宝玲, 等. 宫颈癌术后容积旋转调强放疗与5野调强放疗计划的剂量学比较[J]. 国际放射医学核医学杂志, 2018, 42(1): 41−46. DOI: 10.3760/cma.j.issn.1673-4114.2018.01.008.
Ma JH, Li M, Liu BL, et al. Dosimetric comparison between volumetric modulated arc radiotherapy and five fields intensity-modulated radiation therapy for postoperative cervical carcinoma[J]. Int J Radiat Med Nucl Med, 2018, 42(1): 41−46. DOI: 10.3760/cma.j.issn.1673-4114.2018.01.008.[10] Urso P, Lorusso R, Marzoli L, et al. Practical application of Octavius®-4D: characteristics and criticalities for IMRT and VMAT verification[J/OL]. J Appl Clin Med Phys, 2018, 19(5): 517−524[2021-04-19]. https://aapm.onlinelibrary.wiley.com/doi/10.1002/acm2.12412. DOI: 10.1002/acm2.12412. [11] Rajasekaran D, Jeevanandam P, Sukumar P, et al. A study on correlation between 2D and 3D gamma evaluation metrics in patient-specific quality assurance for VMAT[J]. Med Dosim, 2014, 39(4): 300−308. DOI: 10.1016/j.meddos.2014.05.002. [12] 姜仁伟, 郭栓栓, 陈舒婷, 等. 利用ArcCHECK在实际机架角与零机架角的IMRT剂量验证结果比较[J]. 中华放射肿瘤学杂志, 2017, 26(1): 66−68. DOI: 10.3760/cma.j.issn.1004-4221.2017.01.015.
Jiang RW, Guo SS, Chen ST, et al. A comparative study of ArcCHECK measurements at actual and zero degree gantry angles for dose verification of intensity-modulated radiotherapy[J]. Chin J Radiat Oncol, 2017, 26(1): 66−68. DOI: 10.3760/cma.j.issn.1004-4221.2017.01.015.[13] 王宁, 王彬, 陈阿龙, 等. IMRT计划剂量验证通过率对机架角度误差灵敏度分析[J]. 中华放射肿瘤学杂志, 2016, 25(12): 1327−1330. DOI: 10.3760/cma.j.issn.1004-4221.2016.12.012.
Wang N, Wang B, Chen AL, et al. To analyze the sensitivity of passing rates of intensity modulated radiation therapy (IMRT) plans in dose verification against gantry angle errors[J]. Chin J Radiat Oncol, 2016, 25(12): 1327−1330. DOI: 10.3760/cma.j.issn.1004-4221.2016.12.012.[14] Olaciregui-Ruiz I, Vivas-Maiques B, Kaas J, et al. Transit and non-transit 3D EPID dosimetry versus detector arrays for patient specific QA[J]. J Appl Clin Med Phys, 2019, 20(6): 79−90. DOI: 10.1002/acm2.1261. [15] 郭逸潇, 李亚洲, 刘志强, 等. Octavius1500电离室矩阵基于模体和CT影像剂量验证的分析[J]. 辐射研究与辐射工艺学报, 2021, 39(2): 37−46. DOI: 10.11889/j.1000-3436.2021.rrj.39.020302.
Guo YX, Li YZ, Liu ZQ, et al. Dose verification based on phantom and CT images using Octavius 1500 detector[J]. J Radiat Res Radiat Process, 2021, 39(2): 37−46. DOI: 10.11889/j.1000-3436.2021.rrj.39.020302.