目的:通过Delta4高分辨率模式研究空间分辨率变化对剂量验证γ通过率的影响。方法:随机选取11例鼻咽癌制定VMAT治疗计划,利用Delta4自带的Merge功能获取3组不同分辨率的实测剂量分布,分别为原始分辨率组和高分辨率组(offset=2.5 mm和offset=5 mm),利用SPSS软件对3组实测数据进行统计学分析。结果:2种高分辨率组的剂量测量点较原始分辨率组均有不同程度的增加;高分辨率组offset为5 mm的γ分析通过率较offest为2.5 mm的稍低,但两者均低于原始分辨率组,差异无统计学意义。结论:利用Delta4的Merge功能可以获取更多的剂量测量点参与剂量比较,验证结果更加真实可靠,一般情况下可替代传统胶片验证。 |
Objective: To study the impact of spatial resolution of measurement on Gamma rate in the dose verification through the Delta4 high resolution mode. Methods: 11 volume modulated arc therapy (VMAT)treatment plans of nasopharyngeal carcinoma were randomly chosen, and 3 groups of measured dose distribution with different resolution for each patient, including a original resolution group and two high resolution groups (offset=2.5 mm and offset=5 mm), were obtained by Delta4 using the Merge function. In addition, the paired t-test with SPSS software was applied for the three groups of data. Results: The number of measured dose points of the two high resolution groups increased in different degrees, compared with the original resolution group; the Gamma rate of the high resolution group with 5 mm offset was slightly lower than that of the group with 2.5 mm offset, besides, the Gamma rates of both high resoulution groups were lower than that of the original resolution group, which had no significant difference. Conclusion: More measured dose points can be accessed by the Merge function of Delta4 to obtain more reliable dose verification results, furthermore, the traditional film can be replaced in dose verification under general conditions. |
[1] BORTFELD T,BOYER A L,SCHLEGEL W,et al.Realization and verification of three dimensional conformal radiotherapy with modulated fields[J].Int J Radiat Oncol Biol Phys,1994,30(4):899-908.
[2] TSAI J S,WAZER D E,LING M N,et al.Dosimetric verification of the dynamic intensity modulated radiation therapy of 92 patients[J].Int J Radiat Oncol Biol Phys,1998,40(5):1213-1230.
[3] CHILDRESS N L,SALEHPOUR M,DONG L,et al.Dosimetric accuracy of Kodak EDR2 film for IMRT verifications[J].Med Phys,2005,32(2):539-548.
[4] POPPE B,BLECHSCHMIDT A,DIOUGUELA A,et al.Two-dimensional ionization chamber arrays for IMRT plan verification[J].Med Phys,2006,33(4):1005-1015.
[5] 林珠,吴丽丽,陆佳扬.Delta4三维剂量验证系统的原理及应用[J].医疗装备,2013,7:14-16.
[6] PALMA D,VOLLANS E,JAMES K,et al.Volumetric modulated are therapy for delivery of prostate radiotherapy:comparison with intensity-modulated radiotherapy and three-dimensional conformal radiotherapy[J].Int J Radiat Oncol Biol Phys,2008,72(4):996-1001.
[7] SHAFFER R,NICHOL A M,VOLLANS E,et al.A comparison of volumetric modulated arc therapy and conventional intensity modulated radiotherapy for frontal and temporal high-grade gliomas[J].Int J Radiat Oncol Biol Phys,2010,76(4):1177-1184.
[8] VERBAKEL W F,CUIJPERS J P,HOFFMANS D,et al.Volumetric intensity-modulated are therapy vs.conventional IMRT in headand-neck cancer:a comparative planning and dosimetric study[J].Int J Radiat Oncol Biol Phys,2009,74(1):252-259.
[9] 张伟,马照,邵鹏,等.Delta4的临床应用研究[J].中华放射肿瘤学杂志,2010,19(1):48-51.
[10] 唐媛媛,裴忠玲.鼻饲对鼻咽癌患者放疗期间营养状态及放疗毒副反应的影响[J].现代医学,2014,42(8):939-942.
[11] ROBAR J L,CLARK B G.A practical technique for verifica- tion of three-dimensional conformal dose distributions in stereotactic radiosurgery [J].Med Phys,2000,27(5):978-987.
[12] NYQUIST H.Certain topics in telegraph transmission theory [J].TransA IEE,1928,47(1):617-644. |
