Journal of Jilin University Medicine Edition ›› 2016, Vol. 42 ›› Issue (01): 120-124.doi: 10.13481/j.1671-587x.20160124

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Dosimetric comparison between IMRT and a single full arc,two full arc VMAT for postoperative cervical cancer patients

ZHOU Jieping1, WANG Peng2, QIAN Liting2, WU Aidong1   

  1. 1. Medical Physics Room, Anhui Provincial Cancer Hospital, Hefei 230001, China;
    2. Department of Radiotherapy, Anhui Provincial Cancer Hospital, Hefei 230001, China
  • Received:2015-08-10 Published:2016-01-26

Abstract:

Objective: To compare the planning quality,treatment efficiency and delivery accuracy for treating the postoperative cervical cancer patients with intensity modulated radiotherapy (IMRT)and two kinds of volumetric modulated arc therapy (VMAT),and to provide the reference basis for selecting the number of arcs in the VMAT treatment of postoperative cervical cancer in clinic.Methods: Twenty patients with cervical cancer after operation were planned with the same dose prescription and optimization parameters by means of 7-field IMRT (7F-IMRT),a single full arc (Arc1)and two full arc (Arc2)VMAT,respectively. The dosimetric differences of planning target volumes (PTV)and organs at risk (OAR),the number of monitor units (MU)and treatment delivery time and the accuracy of treatment plan dose verification were compared among the three treatment plans.Results: The conformity index (CI)and the dose distribution homogeneity index (HI)of PTV for Arc2 plan were best (P<0.05),and 7F-IMRT was superior to Arc1 plan (P<0.05).The value of V50 in the the rectum,V40 and V10 in small bowel for Arc2 plan were lowest (P<0.05),while the near-maximum absorbed dose (D2cc),the mean dose(Dmean)and the values of V50 in rectum,bladder,and small bowel for Arc1 plan were higher than 7F-IMRT(P<0.05 or P<0.01). Compared with 7F-IMRT plan,the number of MU and treatment delivery time for Arc2 plan were decreased by 24% and 54%, respectively (P<0.01). There were no significant differences in the pass ratios of 3mm/3% γ analysis of dose verification among three plans (P>0.05).Conclusion: A single full arc of VMAT is difficult to meet the clinical requirements for the postoperative cervical cancer patients. At least two full arcs should be chosen,and the treatment time can be shortened;as a result,there will reduce the fractional error and patient discomfort.

Key words: uterine cervical neoplasms/radiotherapy, intensity modulated radiotherapy, volumetric modulated arc therapy

CLC Number: 

  • R730.55