两种放疗计划系统用于鼻咽癌螺旋断层调强放疗计划的剂量学比较

苏灿森; 孙文钊; 黄晓延

doi:10.3760/cma.j.cn121381-202206001-00333

两种放疗计划系统用于鼻咽癌螺旋断层调强放疗计划的剂量学比较

Dosimetric comparison of helical tomotherapy plans for nasopharyngeal carcinoma with two radiotherapy planning systems

摘要

摘要:
目的比较Ray Station 7（V6.99）和螺旋断层放射治疗（TOMO）（Hi-Art@V5.1.3）2种放疗计划系统设计鼻咽癌螺旋断层调强放疗计划的剂量学差异。
方法回顾性分析2018年5至12月于中山大学肿瘤防治中心完成TOMO治疗计划的15例鼻咽癌患者的临床资料，其中男性11例、女性4例，年龄（44.0±17.7）岁，按照与TOMO治疗计划系统相同的计划设置参数和临床剂量学的要求，在Ray Station 7治疗计划系统中设计TOMO计划。比较2种治疗计划系统设计的计划质量，分析100%、95%处方剂量覆盖靶区的体积占靶区总体积的百分比（V₁₀₀、V₉₅），覆盖靶区1%、98%、99%体积的剂量（D_1%、D_98%、D_99%），均匀性指数（HI）和适形指数（CI），重要危及器官的剂量学指标，计划优化时间和计划执行时间。符合正态分布的计量资料的组间比较采用配对样本t检验的双侧检验。
结果 Ray Station 7和TOMO 计划的鼻咽癌原发病灶的计划靶区（PTV_nx）的V₁₀₀（97.5±2.1）%对（94.9±3.9）%，原发病灶侵犯区域的计划靶区（PTV1）的V₁₀₀（98.5±1.4）%对（99.1±0.9）%、V₉₅（99.3±0.7）%对100.0%，以原发病灶侵犯区域的临床靶区（CTV1）和双侧淋巴结病灶的大体肿瘤靶区（GTV_nd）外扩+GTV_nd所在淋巴引流区+需要预防性放疗的阴性淋巴引流区的计划靶区（PTV2）的V₁₀₀（98.6±1.1）%对（98.9±0.9）%、V₉₅（99.1±0.9）%对（99.8±0.2）%、CI（74.8±5.7）%对（79.2±8.3）%，基于脊髓外扩形成的计划危及器官靶区（PRV-SC）中包绕1 ml体积的等剂量线对应的剂量（D_{1 ml}）（3 750.0±250.0） cGy对（3 443.6±309.3） cGy、40和30 Gy对应的等剂量线包绕的体积占PRV-SC的百分比V_{40 Gy}（0.7±0.7）%对（0.1±0.1）%、V_{30 Gy}（52.3±29.1）%对（44.6±22.9）%、平均剂量（D_mean）（2 705.5±535.5） cGy对（2 619.4±413.9） cGy，右侧颞叶的D_mean（1 639.5±594.5） cGy对（2 150.3±735.6） cGy的差异均有统计学意义（t=−4.96~6.71，均P<0.05）。PTV_nx的V₉₅（99.7±0.3）% 对（99.8±0.2）%、D_1%（7 008.5±746.5） cGy对（6 996.0±767.0） cGy、D_98%（6 628.0±577.0） cGy对（6 548.8±577.3） cGy、HI（6.2±2.7）% 对（6.3±2.6）%、CI（59.8±26.1）% 对（64.0±24.3）%，双侧淋巴结病灶的计划靶区（PTV_nd）的V₁₀₀（98.5±1.5）%对（98.1±1.9）%、（98.7±1.2）%对（96.6±3.4）%、V₉₅（99.7±0.3）% 对100.0%、100% 对100%、D_99%（6 511.0±500.9） cGy对（6 487.1±483.5） cGy、（6 496.0±484.0） cGy对（6 493.3±466.9） cGy、D_1%（6 824.0±571.0） cGy对（6 815.7±562.6） cGy、（6 851.0±583.0） cGy对（6 807.0±587.5） cGy的差异均无统计学意义（t=−1.51~0.90，均P>0.05）。危及器官PRV-SC中50 Gy对应的等剂量线包绕的体积占PRV-SC的百分比（V_{50 Gy}）（0.03±0.03）%对0，基于脑干外扩形成的计划危及器官靶区（PRV-BS）的D_mean（2 511.0±792.0） cGy对（2 397.0±310.6） cGy、D_1%（4 880.0±1 600.0） cGy对（5 254.6±755.1） cGy、60 Gy对应的等剂量线包绕的体积占PRV-BS体积的百分比（V_{60 Gy}）（1.6±1.6）%对（3.6±3.6）%，双侧腮腺D_mean（3 986.5±836.5） cGy对（3 953.1±425.6） cGy、（4 223.0±708.0） cGy对（4 205.1±800.2） cGy，左侧颞叶D_mean（1 891.5±845.5） cGy对（2 077.1±573.0） cGy，双侧颞叶中60 Gy对应的等剂量线包绕的体积占颞叶体积的百分比（V_{60 Gy}）（6.7±6.7）%对（6.5±6.5）%、（4.0±4.0）%对（5.8±5.8）%的差异均无统计学意义（t=−1.29~1.96，均P>0.05）。Ray Station 7和TOMO 治疗计划系统的剂量均在临床要求范围内。Ray Station 7治疗计划系统用于鼻咽癌的计划优化时间短于TOMO治疗计划系统（3.00±0.58） min 对（120.00±17.00） min，且差异有统计学意义(t=−52.31，P<0.01)，二者的计划执行时间相当（611.0±94.2） s 对（612.2±94.3） s，且差异无统计学意义（t=−0.03，P>0.05）。
结论 2种放疗计划系统设计的鼻咽癌螺旋断层调强放疗计划在剂量学上存在微小差异，均能满足临床要求。Ray Station 7治疗计划系统设计的鼻咽癌螺旋断层调强放疗计划可以明显节约优化时间。

Abstract:
Objective To evaluate the dosimetric difference of helical tomotherapy plans for nasopharyngeal carcinoma via Ray Station 7 (V6.99) and Tomotheraphy (TOMO) (Hi-Art@V5.1.3) treatment planning systems.
Methods This retrospective analysis involved 15 patients of nasopharyngeal carcinoma who completed the TOMO plan in Sun Yat-sen University Cancer Center from May 2018 to December 2018. Among them, 11 cases were males and 4 cases were females, aged (44.0±17.7) years. Using the same prescription dose requirements and dose constraints in TOMO, the plan was designed on the Ray Station 7 treatment planning system. The dosimetric indexes for plan comparison included the 100% and 95% prescription dose coverage of the target volume (V₁₀₀, V₉₅), dose covering 1%, 98%, 99% of the volume of the target volume (D_1%, D_98%, D_99%), homogeneity index (HI), conformity index (CI), key dosimetric indexes for organs at risk, planning optimization time and delivery time of treatment plan. Data from the two groups that fit a normal distribution were compared by paired t-test.
Results The V₁₀₀ of planning target volume of the primary lesion of nasopharyngeal carcinoma (PTV_nx) ((97.5±2.1)% vs. (94.9±3.9)%); V₁₀₀, V₉₅ of planning target volume of the primary lesion invasion (PTV1) ((98.5±1.4)% vs. (99.1±0.9)%, (99.3±0.7)% vs. 100.0%); V₁₀₀, V₉₅, CI of planning target volume of primary lesion invasion clinical target volume (CTV1) and expanded gross tumor volume of bilateral lymph node lesions (GTV_nd) and the lymphatic drainage area where GTV_nd is located and the negative lymphatic drainage area that needs preventive radiotherapy (PTV2) ((98.6±1.1)% vs. (98.9±0.9)%, (99.1±0.9)% vs. (99.8±0.2)%, (74.8±5.7)% vs. (79.2±8.3)%); the dose corresponding to the isodose line surrounding the volume of 1 ml in planning organ at risk volume of spinal cord (PRV-SC) (D_{1 ml}) , the relative volume of the volume surrounded by the isodose line corresponding to 40 and 30 Gy in PRV-SC and the volume of PRV-SC (V_{40 Gy}, V_{30 Gy}), the mean dose (D_mean) of planning organ at risk target volume of the spinal cord ((3 750.0±250.0) cGy vs. (3 443.6±309.3) cGy, (0.7±0.7)% vs. (0.1±0.1)%, (52.3±29.1)% vs. (44.6±22.9)%, (2 705.5±535.5) cGy vs. (2 619.4±413.9) cGy); and D_mean of the right temporal lobe ((1 639.5±594.5) cGy vs. (2 150.3±735.6) cGy) showed statistically significant differences between Ray Station 7 and TOMO plans (t=−4.96−6.71, all P<0.05). The V₉₅, D_1%, D_98%, HI, CI of PTV_nx((99.7±0.3)% vs. (99.8±0.2)%, (7 008.5±746.5) cGy vs. (6 996.0±767.0) cGy, (6 628.0±577.0) cGy vs. (6 548.8±577.3) cGy, (6.2±2.7)% vs. (6.3±2.6)%, (59.8±26.1)% vs. (64.0±24.3)%); V₁₀₀, V₉₅, D_99% and D_1% of planning target volume for bilateral lymph node lesion (PTV_nd) ((98.5±1.5)% vs. (98.1±1.9)% and (98.7±1.2)% vs. (96.6±3.4)%, (99.7±0.3)% vs. 100.0% and 100.0% vs.100.0%, (6 511.0±500.9) cGy vs. (6 487.1±483.5）cGy and (6 496.0±484.0) cGy vs. (6 493.3±466.6) cGy, (6 824.0±571.0) cGy vs. (6 815.7±562.6) cGy and (6 815.0±583.0) cGy vs.(6 807.0±587.5) cGy) of the two groups of plans showed that the difference was not statistically significant (t=−1.51−0.90, all P>0.05). The relative volume of the volume surrounded by the isodose line corresponding to 50 Gy in PRV-SC and the volume of PRV-SC (V_{50 Gy}) ((0.03±0.03)% vs. 0); D_mean of planning organ at risk target volume of brainstem (PRV-BS) ((2 511.0±792.0) cGy vs. (2 397.0±310.6) cGy); D_1% and relative volume of the volume surrounded by the isodose line corresponding to 60 Gy in PRV-BS and the volume of PRV-BS (V₆₀ _Gy) ((4 880.0±1 600.0) cGy vs. (5 254.6±755.1) cGy, (1.6±1.6)% vs. (3.6±3.6)%); D_mean of the bilateral parotid ((3 986.5±836.5) cGy vs. (3 953.1±425.6) cGy and (4 223.0±708.0) cGy vs. (4 205.1±800.2) cGy); D_mean of the left temporal lobe ((1 891.5±845.5) cGy vs. (2 077.1±573.0) cGy; V₆₀ _Gy of the bilateral temporal lobe ((6.7±6.7)% vs. (6.5±6.5)% and (4.0±4.0)% vs. (5.8±5.8)%) of the two groups of plans showed that the differences were not statistically significant (t=−1.29−1.96, all P>0.05). The dosages of two treatment planning systems were within the clinical requirements range. The planning optimization time of Ray Station 7 treatment planning systems for nasopharyngeal carcinoma was significantly faster than that of TOMO treatment planning systems ((3.00±0.58) min vs. (120.00±17.00) min), the difference was statistically significant (t=−52.31, P<0.01), but their delivery times were similar to each other ((611.0±94.2) s vs. (612.2±94.3) s), the difference was not statistically significant (t=−0.03, P>0.05).
Conclusion Statistical analysis of the quality of helical tomotherapy plans for nasopharyngeal carcinoma designed by the two treatment planning systems showed that the differences were not significant, and both can meet clinical dosimetry requirements. Designing a nasopharyngeal carcinoma plan with the Ray Station 7 treatment planning system can significantly save the optimization time.

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