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.