Efficacy of different jaw widths in volumetric modulated arc therapy for cervical cancer

Abstract

Objective To analyze the clinical application of jaw width on cervical cancer from plan quality, plan complexity and γ pass rate in volume moderated arc therapy (VMAT). Methods A total of 20 patients diagnosed as postoperative cervical cancer in the Radiotherapy Center of our hospital from June 2019 to October 2020 were retrospectively recruited, and thery were designed with 4 VMAT plans with Eclipse v13.6. The X1 jaw of Half-V group was set with Tmax, the X2 jaw was set with T0, the jaw width of Arc1-V group was set with 2/3 width of target, and the jaw width of Arc2-V group was set with 5/6 width of target. The X1 jaw of All-V group was set with Tleft max, and the X2 jaw was set with Tright max. The other optimization parameters of all plans were set as the same value. The dosimetric parameters of the target and organ at risk (OAR), plan complexity and γ passing rate were compared and analyzed in the 4 groups of treatment plans. Results There was no significant difference in the dosimetry of planning target volume (PTV) in the 4 groups. Statistical differences were observed in the Dmax values of the left femoral head and small intestine and the V30 and V40 values of the rectum and bladder (P 64 cm2 and MU were significantly correlated with γ pass rate in the 4 groups (P 64 cm2 and γ pass rate presented growth trend, while MU and ALT were in decreasing trend. The MU/CP curve was higher in the Half -V group than the other 3 groups. The AI curve of 4 groups showed slight discrepancy. Conclusion The X-direction jaw setting of the cervical cancer can be selected 2/3 target area width or 5/6 target area width.

Keywords

• cervical cancer
• jaw width
• volume moderated arc therapy
• plan complexity
• pass rate