Abstract：Objective To study dosimetric difference of the orthogonal dual‐layer multileaf collimation (MLC) of domestic linear
accelerator Venus X in the dynamic intensity modulated radiotherapy (IMRT), and to explore the advantages of orthogonal duallayer
MLC in clinical application of radiotherapy. Methods Forty-two tumor patients who had completed clinical treatment with
single-layer gratings were selected retrospectively to compare the dynamic intensity modulated treatment plan based on single-layer
MLC and orthogonal dual-layer MLC respectively, and the dosimetric differences were analyzed. Results Both plans can meet the
prescription requirements. The target conformal index (CI) of the plan based on orthogonal dual-layer MLC was 3.28% higher than
that of single-layer MLC plan, and the difference was statistically significant丨 The homogeneity index (HI) was 8.41% better than
that of single-layer MLC plan. For the protection of organs at risk, the low-dose distribution of the dual-layer MLC plan was smaller,
and the average dose to the organ-at-risk was reduced by 12.20% compared with the single-layer MLC plan, and the difference was
statistically significant (P<0.05). Conclusion The dynamic IMRT plan based on orthogonal dual-layer MLC is superior to singlelayer
MLC in target CI, HI and organ protection, which has advantages in clinical application.
