Dosimetric Comparison of Volumetric and Intensity-modulated Radiotherapy Techniques in Cervical Cancer Patients with Paraaortic Lymph Node Metastasis.

OBJECTIVE To compare the dosimetric criteria of intensity-modulated radiotherapy (IMRT) and volumetric modulated radiotherapy (VMAT) plans with simultaneous integrated boost (SIB) technique in cervical cancer patients with para-aortic lymph node (PALN) metastases. METHODS SIB-IMRT and SIB-VMAT plans of 10 patients were retrospectively analyzed. The elective volume received 45 Gy(PTV45) in 25 fractions of 1.8 Gy, while the integrated boost volume (lymph nodes) simultaneously received 55 Gy (PTV55). Using the same dose constraints in optimization, IMRT plans consisted of 9 fields, while VMAT plans were performed with 2 full arcs. Volume and dose parameters were determined across the planning target volume, bladder, bowel, femoral heads, kidneys, liver, rectum, sigmoid, and spinal cord. Conformity and homogeneity indices were calculated, the Monitor Unit (MU) was analyzed, and the Wilcoxon-signed rank test was applied for statistical analysis (p≤0.05). RESULTS Both techniques were found to be effective for treatment, but there was a significant difference in favor of SIB-VMAT in terms of target volume reaching the predicted dose and protection of critical organs (OAR) (p=0.028). For PTV55, MU and right-left kidney; V20, V30 - V20, V30, liver; Dort, liver values were significantly different (p=0.005, p=0.005, p=0.005, p=0.02, p=0.005, p=0.007, p=0.03, respectively). In SIB-IMRT, a significant difference was observed for CI value close to 1 (p=0.02). CONCLUSION The SIB-VMAT technique showed lower MU, kidney, and liver values, and SIB-IMRT showed better CI values. Other parameters indicated that the two planning techniques were nearly equivalent. These findings indicate the different efficacies of treatment techniques in radiotherapy planning for cervical cancer patients who were diagnosed with PALN metastases. [ABSTRACT FROM AUTHOR]