固定野静态及动态调强和容积旋转调强在宫颈癌术后放疗中的剂量学比较
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摘要
目的探讨容积旋转调强放疗(VMAT)、固定野动态调强放疗(Dmlc-IMRT)以及静态调强放疗(Step&shoot-IMRT)3种技术在宫颈癌术后放疗中的剂量学差异和适用性。方法选取20例宫颈癌术后病人,分别进行VMAT、Dmlc-IMRT和Step&shoot-IMRT计划设计,通过剂量体积直方图比较3种计划的靶区剂量分布、适形度、均匀性、低剂量受照体积、危及器官剂量分布,记录并比较机器跳数和治疗时间。结果 VMAT和DmlcIMRT在靶区的适形度和均匀性上均优于Step&shoot-IMRT,差异具有统计学意义(F=12.34、31.64,P<0.05)。VMAT的低剂量受照体积较Dmlc-IMRT和Step&shoot-IMRT略有增加,但差异无显著性。小肠和膀胱等危及器官的剂量分布,Dmlc-IMRT总体低于VMAT和Step&shoot-IMRT,计划质量较高。VMAT计划的治疗时间较Step&shoot-IMRT计划减少了49%,较Dmlc-IMRT计划减少了35%。结论 VMAT计划质量可以达到或优于Step&shoot-IMRT计划质量,较另两种计划极大缩短了治疗时间,适用于长时间放疗过程中控制力差的病人和繁忙的放疗中心。当采用Step&shoot-IMRT技术难以确保计划质量时,换用Dmlc-IMRT技术,基本可以优化所有剂量评价参数。
Objective To investigate the dosimetric differences and applicability of volume modulated arc therapy(VMAT),dynamic intensity-modulated radiotherapy(Dmlc-IMRT)and static intensity-modulated radiotherapy(Step&shoot-IMRT)in postoperative radiotherapy for cervical cancer. Methods Twenty patients with cervical cancer after operation were selected.Plans of VMAT,Dmlc-IMRT and Step&shoot-IMRT were designed,respectively,for the 20 patients.Applying dose volume histogram(DVH),target dose distribution,conformal and uniformity,low dose irradiation volume and organ threatening dose distribution among three plans were compared,and the machine hops and treatment time were recorded and compared as well. Results On the shape and uniformity of target area,VMAT and Dmlc-IMRT plans were better than that of Step&shoot-IMRT,the difference being statistically significant(F=12.34,31.64;P <0.05).The low dose irradiation volume of the VMAT plan was slightly higher than that of Dmlc-IMRT and Step&shoot-IMRT,but the difference in that was not significant.As for the dose distribution of organs at risk-such as small bowel and bladder-the Dmlc-IMRT was overall lower than VMAT and Step&shootIMRT,the Dmlc-IMRT plan quality being the best.The treatment time of VMAT was 49%lower than that of Step&shoot-IMRT and 35%lower than that of Dmlc-IMRT. Conclusion VMAT plan quality can meet or exceed Step&shoot-IMRT plan quality,and the time of treatment is greatly shortened as compared with the other two schemes,which is suitable for patients with poor control of long term radiotherapy and in some busy radiotherapy centers.When Step&shoot-IMRT technology is difficult to ensure the quality of the plan,replacing Dmlc-IMRT technology,all dose evaluation parameters can basically be optimized.
Objective To investigate the dosimetric differences and applicability of volume modulated arc therapy(VMAT),dynamic intensity-modulated radiotherapy(Dmlc-IMRT)and static intensity-modulated radiotherapy(Step&shoot-IMRT)in postoperative radiotherapy for cervical cancer. Methods Twenty patients with cervical cancer after operation were selected.Plans of VMAT,Dmlc-IMRT and Step&shoot-IMRT were designed,respectively,for the 20 patients.Applying dose volume histogram(DVH),target dose distribution,conformal and uniformity,low dose irradiation volume and organ threatening dose distribution among three plans were compared,and the machine hops and treatment time were recorded and compared as well. Results On the shape and uniformity of target area,VMAT and Dmlc-IMRT plans were better than that of Step&shoot-IMRT,the difference being statistically significant(F=12.34,31.64;P <0.05).The low dose irradiation volume of the VMAT plan was slightly higher than that of Dmlc-IMRT and Step&shoot-IMRT,but the difference in that was not significant.As for the dose distribution of organs at risk-such as small bowel and bladder-the Dmlc-IMRT was overall lower than VMAT and Step&shootIMRT,the Dmlc-IMRT plan quality being the best.The treatment time of VMAT was 49%lower than that of Step&shoot-IMRT and 35%lower than that of Dmlc-IMRT. Conclusion VMAT plan quality can meet or exceed Step&shoot-IMRT plan quality,and the time of treatment is greatly shortened as compared with the other two schemes,which is suitable for patients with poor control of long term radiotherapy and in some busy radiotherapy centers.When Step&shoot-IMRT technology is difficult to ensure the quality of the plan,replacing Dmlc-IMRT technology,all dose evaluation parameters can basically be optimized.
引文
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[9]刘丽虹,韩春.容积旋转调强放射治疗的临床应用[J].肿瘤防治研究,2013,40(9):903-907.
[10]张玉海,李月敏,夏火生,等.宫颈癌术后不同放疗技术剂量学比较研究[J].中国医学物理学杂志,2010,27(1):1583-1587.
[2]梁健,黄思娟,张树芝,等.全段食管癌旋转容积调强与固定野静态调强和三维适形放疗计划的剂量学比较[J].中山大学学报(医学科学版),2016,37(4):597-601.
[3]ZHANG R,BAI W,GAO Y,et al.SU-E-P-55:the reaserch ofcervicalcancerdeliveredwithconstant dose rate and gantry speed arc therapy(CDR-CAS-IMAT)on conventional linac[J].Med Phys,2015,42(6):879-886.
[4]曹倩倩,刘路,朱丽红,等.三维适形、固定野动态调强和容积旋转调强在宫颈癌术后放疗中的剂量学比较[J].中国妇产科临床杂志,2015,16(1):15-18.
[5]KANG H J,KAY C S,SON S H,et al.Hypofractionated intensity-modulated radiotherapy in patients with localized prostate cancer:apreliminary study[J].Radiat Oncol J,2016,34(1):45-51.
[6]李军,陈雪梅,张西志,等.宫颈癌术后常规与旋转容积调强放疗计划剂量学研究[J].中华肿瘤防治杂志,2014,21(14):1104-1108.
[7]孙小梅,丁丽娟,董丽华,等.容积旋转调强与固定野调强在晚期宫颈癌放疗的剂量学比较及疗效观察[J].中华放射医学与防护杂志,2016,36(7):509-512.
[8]NAKONECHNY K,TRAN M,SASAKI D,et al.Poster-53:improving inter-linac DMLC IMRT dose precision by fine tuning of MLC leaf calibration[J].Med Phys,2016,43(8):4949.
[9]刘丽虹,韩春.容积旋转调强放射治疗的临床应用[J].肿瘤防治研究,2013,40(9):903-907.
[10]张玉海,李月敏,夏火生,等.宫颈癌术后不同放疗技术剂量学比较研究[J].中国医学物理学杂志,2010,27(1):1583-1587.