Dosimetric comparison of fixed field dynamic IMRT and VMAT techniques in simultaneous integrated boost radiotherapy of prostate cancer

High-risk prostate cancer can take advantage of the combination of hypofractionated radiotherapy and pelvic conventional fraction radiotherapy. The comparison between fixed field dynamic IMRT and VMAT techniques can provide suggestions for clinical treatment. We selected 10 high-risk prostate cancer patients who received radiotherapy at the cancer center of Sun Yat-sen University from January 2016 to December 2019. The targets contained in prostate, seminal vesicles and pelvic lymph nodes. With the same prescription and optimized parameters, 9F, single-arc (1ARC) and double-arc (2ARC) treatment plans were developed. The dose distribution of the targets, OAR, MU, treatment time and gamma pass ratios of dose verification was compared. The D 2% (69.37 ± 0.89) Gy, D 50% (66.92 ± 0.63) Gy, HI (0.09 ± 0.02), and CI (0.83 ± 0.05) of PTV1 in 9F were slightly better than those of 1ARC which were (71.13 ± 1.21) Gy, (68.50 ± 0.76) Gy, (0.12 ± 0.02), (0.74 ± 0.07), except D 98% , the difference was significant ( P .05). The V 95% (99.45 ± 0.78)% of PTV2 in 9F was slightly better than that in 1ARC (99.35 ± 1.28)%. The difference was significant ( P .05). The D mean of the bladder and the V67.5 Gy of rectum between all three plans were similar. The D mean of left and right femoral in 1ARC and 2ARC were lower than that in 9F, and the difference was significant ( P