Purpose:We study the dosimetric effect on the target volume,organs at risk(OARs)and normal tissues based on the different choice for four types of variables,namely,treatment position,dose calculation algorithm,mulitleaf collimator(MLC)motion mode and X-ray energy.We also discuss the optimum treatment mode applied to post-operative cervical cancer for five-field intensity-modulated radiation therapy(5F-IMRT)technique.Methods:The dosimetric difference on the target volume and OARs under the influence of four types of variables was compared by changing one variable at a time.Then,based on the above comparison results,the dosimetric difference on planning target volume(PTV)and OARs between group A,which comprised the superior four variables and group B,which comprised the relatively inferior four variables,was made.The dosimetric parameters included the dose distribution of the target volume,OARs and normal tissues,conformal index(CI),homogeneity index(HI),monitor units(MU)and beam-on time(T).The independent and paired t-tests were chosen for statistical analysis,and results were considered statistically significant(P≤0.05).Results:Compared with supine position,the maximum dose of PTV(Dmax-PTV),the maximum dose of small intestine(Dmax-small intestine)and V50 of bladder(V50-bladder)were all lower in prone position.In contrast with the Pencil Beam Convolution(PBC),CI of PTV(CI-PTV)was larger while the HI of PTV(HI-PTV)was lower,both V50-bladder and the maximum dose of rectum(Dmax-rectum)were lower using Anisotropic Analytical Algorithm(AAA).Moreover,the same results were obtained using sliding window(SW)compared with multiple static segments(MSS).Compared with 6MV X-ray,the mean dose of PTV(Dmean-PTV)and CI-PTV were larger while the maximum dose of spinal cord(Dmax-spinal cord),V50-bladder and the maximum dose of femoral heads were lower with the 15MV X-ray.In comparison with group B comprising the supine position,PBC,MSS and 6MV X-ray,Dmean-PTV and HI-PTV decreased 1.4%and 53.4%respectively,CI-PTV increased 5.8%medially,while Dmax-small intestine,Dmax-rectum,V50-bladder and Dmax-femoral heads all decreased in group A that comprised the prone position,AAA,SW and 15MV X-ray.Conclusion:The treatment mode of prone position,AAA algorithm,SW and 15MV X-ray is chosen for the post-operative cervical cancer of 5F-IMRT technique,which is more capable of meeting the target volume constraints and maximal protection of OARs.