华西医学

华西医学

胃癌放射治疗中静态调强计划射野和子野的优化研究

查看全文

目的 比较胃癌术后不同布野方案及子野数设置的静态调强计划质量差异,研究胃癌术后调强放射治疗(放疗)计划设计中较优的射野及子野数设置。 方法 采用随机抽样法选择四川大学华西医院 2013 年 2 月 1 日—8 月 30 日接受胃癌术后辅助放疗的 15 例患者入组研究,在每例患者原有的个体化 5 野调强计划的基础上,在相同的放疗计划系统 Pinnacle 9.2 中重新对每例患者进行 4 种不同共面布野方案的静态调强计划设计:布野方案一为 7 野等角度均分静态调强计划;方案二为 5 野等角度均分静态调强计划;方案三为 4 野静态调强计划,射野方向为 310、20、90、180°;方案四为 3 野静态调强计划,射野方向为 310、65、180°。对于 4 种不同布野方案的静态调强计划,设置最大子野数为 65。对于布野方案三,改变最大子野数 65 的设置为 45 和 25,另得 2 个不同的静态调强计划。分析对比 15×7 个静态调强计划结果中靶区和危及器官的剂量体积参数、机器跳数和治疗时间。 结果 当最大子野数为 65 时,使用 4 野调强计划相对于临床 5 野调强计划在靶区适形度方面稍有提高(0.74±0.04 vs. 0.73±0.05,P<0.01),在对危及器官肝脏[如受到 30 Gy 照射的百分体积V30:(22.71±6.10)% vs. (24.03±6.84)%,P<0.01]和肾脏[如右肾V20:(14.97±6.72)% vs. (19.41±6.14)%,P<0.01]的保护上优势明显。与最大子野数为 65 的 4 野调强计划相比,最大子野数为 45 和 25 的 4 野调强计划靶区适形度有所降低(0.74±0.04vs. 0.73±0.04 vs. 0.71±0.04,P<0.05),但仍在临床可接受的范围内,且继续保持了对危及器官肝脏和肾脏的保护优势;治疗时间分别平均减少了 1.8、4.3 min[(494.66±26.79)vs. (384.26±14.99)vs. (235.00±9.21) s,P<0.01];治疗效率分别提高了 22.3% 和 52.4%,且该结果具有统计学意义(P<0.05)。 结论 在胃癌辅助放疗中,使用较少射野和子野数的 4 野静态调强技术在保证计划质量的同时,更好地保护了危及器官,尤其是肝脏和肾脏,并且减少了照射时间,提高了治疗效率。

Objective To compare the static intensity-modulated radiation therapy (IMRT) plans using different beams sets and segments number and find the better static IMRT plan sets on beams and segments in gastric surgical adjuvant radiotherapy. Methods Fifteen patients who underwent adjuvant radiotherapy for gastric cancer between February 1st and August 30th, 2013 were chosen as subjects through random sampling. Based on the 5 beams static IMRT plans already used in clinical practice, four different static IMRT plans used diverse beams sets for each patient were designed in the same treatment planning system (Pinnacle 9.2). The beams sets of static IMRT plans were as follows: 7 coplanar equal beams; 5 coplanar equal beams; 4 coplanar beams of 310, 20, 90 and 180°; 3 coplanar beams of 310, 65 and 180°. Sufficient segments 65 was set as the max segments number in order to compare the plans’ difference just resulting from beams. In the second step, the max segments number was changed from 65 to 45 and 25 to design two different static IMRT plans for the 4 coplanar beams static IMRT plans. The dosimetric parameters were compared for the planning target volume (PTV) and organs at risk (OARs). The monitor units and treatment times of the different static IMRT plans were also evaluated. Results When the max segments number was set to 65, the 4 coplanar beams static IMRT plans were a little better on PTV conformability than the 5 coplanar beams static IMRT plans used in clinical practice (0.74±0.04 vs. 0.73±0.05, P<0.01). Meanwhile, better OARs dose sparing especially for liver and kidneys were gained by the 4 coplanar beams static IMRT plans, for example, the percent volume gained 30 Gy for liver [(22.71±6.10)%vs. (24.03±6.84)%, P<0.01] and the percent volume gained 20 Gy for the right kidney [(14.97±6.72)%vs. (19.41±6.14)%, P<0.01]. The PTV conformability of the 4 coplanar beams static IMRT plans reduced as the max segments number became smaller (0.74±0.04vs. 0.73±0.04 vs. 0.71±0.04, P<0.05). However, they were still acceptable in clinical practice. And the better dose sparing for liver and kidneys were retained. The average reductions of 1.8 and 4.3 minutes on the irradiation time were get by the 4 coplanar beams static IMRT plans with the max segments number 45 and 25 compared to that with the max segments number 65 [(494.66±26.79)vs. (384.26±14.99) vs. (235.00±9.21) s, P<0.01]. And the raises of treatment efficiency were 22.3% and 52.4%, respectively (P<0.05). Conclusions The 4 coplanar beams static IMRT plans with fewer segments could ensure plan quality, and protect the OARs better in the meanwhile, especially for liver and kidneys. The treatment time is reduced as well. The 4 coplanar beams static IMRT plans could improve the treatment efficiency.

关键词: 胃癌; 静态调强放射治疗; 布野方案; 子野数; 计划质量; 治疗时间

Key words: Gastric cancer; Static intensity-modulated radiation therapy; Beams sets; Segments number; Plan quality; Delivery time

登录后 ,请手动点击刷新查看全文内容。 没有账号,
登录后 ,请手动点击刷新查看图表内容。 没有账号,
1. Torre LA, Bray F, Siegel RL, et al. Global cancer statistics, 2012. CA Cancer J Clin, 2015, 65(2): 87-108.
2. Sasako M, Sano T, Yamamoto S, et al. D2 lymphadenectomy alone or with para-aortic nodal dissection for gastric cancer. N Engl J Med, 2008, 359(5): 453-462.
3. Lim DH, Kim DY, Kang MK, et al. Patterns of failure in gastric carcinoma after D2 gastrectomy and chemoradiotherapy: a radiation oncologist's view. Br J Cancer, 2004, 91(1): 11-17.
4. Yoo CH, Noh SH, Shin DW, et al. Recurrence following curative resection for gastric carcinoma. Br J Surg, 2000, 87(2): 236-242.
5. Macdonald JS, Smalley SR, Benedetti J, et al. Chemoradiotherapy after surgery compared with surgery alone for adenocarcinoma of the stomach or gastroesophageal junction. N Engl J Med, 2001, 345(10): 725-730.
6. Park SH, Sohn TS, Lee J, et al. Phase Ⅲ trial to compare adjuvant chemotherapy with capecitabine and cisplatin versus concurrent chemoradiotherapy in gastric cancer: final report of the adjuvant chemoradiotherapy in stomach tumors trial, including survival and subset analyses. J Clin Oncol, 2015, 33(28): 3130-3136.
7. Alani S, Soyfer V, Strauss N, et al. Limited advantages of intensity-modulated radiotherapy over 3D conformal radiation therapy in the adjuvant management of gastric cancer. Int J Radiat Oncol Biol Phys, 2009, 74(2): 562-566.
8. Milano MT, Garofalo MC, Chmura SJ, et al. Intensity-modulated radiation therapy in the treatment of gastric cancer: early clinical outcome and dosimetric comparison with conventional techniques. Br J Radiol, 2006, 79(942): 497-503.
9. Hoogeman MS, Nuyttens JJ, Levendag PC, et al. Time dependence of intrafraction patient motion assessed by repeat stereoscopic imaging. Int J Radiat Oncol Biol Phys, 2008, 70(2): 609-618.
10. Teoh M, Clark CH, Wood K, et al. Volumetric modulated arc therapy: a review of current literature and clinical use in practice. Br J Radiol, 2011, 84(17): 967-996.
11. Edge SB, Compton CC. The American joint committee on cancer: the 7th edition of the AJCC cancer staging manual and the future of TNM. Ann Surg Oncol, 2010, 17(6): 1471-1474.
12. Hess CF, Christ G, Jany R, et al. Dosage specification at the ICRU reference point: the consequences for clinical practice. Strahlenther Onkol, 1993, 169(11): 660-667.
13. Wambersie A, Landberg T, Prescribing GR. Recording and reporting photon beam therapy: the problem of margins (the recent ICRU recommendations, Report 62, 1999). Patras Medical Physics, 1999, 99(1): 25-31.
14. Smalley SR, Gunderson L, Tepper J, et al. Gastric surgical adjuvant radiotherapy consensus report: Rationale and treatment implementation. Int J Radiat Oncol Biol Phys, 2002, 52(2): 283-293.
15. Tepper JE, Gunderson LL. Radiation treatment parameters in the adjuvant postoperative therapy of gastric cancer. Semin Radiat Oncol, 2002, 12(2): 187-195.
16. Daly-Schveitzer N, Julieron M, Tao YG, et al. Intensity-modulated radiation therapy (IMRT): toward a new standard for radiation therapy of head and neck cancer?. Eur Ann Otorhinolaryngol Head Neck Dis, 2011, 128(5): 241-247.
17. Gomez-Millan J, Fernandez JR, Medina CJ. Current status of IMRT in head and neck cancer. Reports of practical oncology and radiotherapy. Rep Pract Oncol Radiother, 2013, 18(6): 371-375.
18. Arbea L, Ramos L, Martinez-Monge R, et al. Intensity-modulated radiation therapy (IMRT) vs. 3D conformal radiotherapy (3DCRT) in locally advanced rectal cancer (LARC): dosimetric comparison and clinical implications. Radiat Oncol, 2010, 5: 17.
19. Chung HT, Lee B, Park E, et al. Can all centers plan intensity-modulated radiotherapy (IMRT) effectively? An external audit of dosimetric comparisons between three-dimensional conformal radiotherapy and IMRT for adjuvant chemoradiation for gastric cancer. Int J Radiat Oncol Biol Phys, 2008, 71(4): 1167-1174.
20. Dzierma Y, Nuesken FG, Fleckenstein JA, et al. Comparative planning of flattening-filter-free and flat beam IMRT for hypopharynx cancer as a function of beam and segment number. PLoS One, 2014, 9(4): e94371.
21. Bzdusek K, Friberger H, Eriksson K, et al. Development and evaluation of an efficient approach to volumetric arc therapy planning. Med Phys, 2009, 36(6): 2328-2339.
22. Fung-Kee-Fung SD, Hackett R, Hales L, et al. A prospective trial of volumetric intensity-modulated arc therapy vs conventional intensity modulated radiation therapy in advanced head and neck cancer. World J Clin Oncol, 2012, 3(4): 57-62.
23. Bewes JM, Suchowerska N, Jackson M, et al. The radiobiological effect of intra-fraction dose-rate modulation in intensity modulated radiation therapy (IMRT). Phys Med Biol, 2008, 53(13): 3567-3578.
24. Bratengeier K, Gainey MB, Flentje M. Fast IMRT by increasing the beam number and reducing the number of segments. Radiat Oncol, 2011, 6: 170.