The Dosimetric Performance of Volumetric Modulated Arc Therapy and Intensity Modulated Radiation Therapy in the Treatment of Locally Advanced Laryngeal Cancer

Abstract

Background: This study aims to compare the performance of intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) in treating laryngeal cancer.Method: In this retrospective dosimetric study, 15 patients diagnosed with locally advanced laryngeal cancer (LALC) were selected. The dosimetric performance of the two techniques was analyzed using 6 MV X-rays, based on dose-volume histograms for primary and boost planning target volumes (PTVp and PTVb, respectively), relevant organs at risk (OARs), mean Dose (Dmean), maximum Dose (Dmax), 95% Dose (D95), 2% Dose (D2%), 5% Dose (D5%), monitor units per segment (MU/segment), number of MU/cGy, treatment delivery time, along with conformity and homogeneity indices.Results: Both techniques were able to achieve favorable equivalent uniform doses and low doses to OARs. The average total number of monitor units for IMRT was significantly greater than that for VMAT (1724.5 ± 249.5 and 475.3 ± 47.0, respectively for PTVp and 601.4 ± 81.7 and 458.0 ± 62.6, respectively for PTVb). The modulation factor (MU/cGy) of IMRT was significantly greater than that for VMAT for both the primary and the boost phases. The mean treatment delivery time for all cases of IMRT was significantly longer than that of VMAT.Conclusion: The primary distinction between IMRT and VMAT in the treatment of LALC is that VMAT requires significantly fewer monitor units (one-third) compared with IMRT. This reduction contributes to a decrease in treatment time, which in turn positively impacts patient comfort and the accuracy of treatment.

Keywords

• radiotherapy
• intensity-modulated
• dvh
• organs at risk
• ptv