Objective  By comparing the effects of installing 3d-printed bolus with or without positioning holes on the skin fit and patient dose distribution, the advantages and disadvantages of the two installation methods in the application of radiotherapy after radical breast cancer surgery were evaluated, and the reference was provided for clinical application.

Methods  A total of 48 patients (34 patients with and 14 patients without positioning holes) who received radiotherapy for breast cancer in Suining Central Hospital from December 2022 to August 2024 were randomly selected. Three dimensional reconstruction of the air gap between the patient body surface and the 3d-printed bolus was conducted, and the tissue dose distribution of each case was analyzed. Comparative analysis was conducted using t-test to analyze the differences of the skin fit and the key dosimetric indexes of target areas and organs at risk between the two bolus installation methods.

Results The mean values of the maximum air gap height, air gap area and air gap volume of the group with positioning holes were lower than those of the group without positioning holes (P<0.05), and the skin fit showed better consistency. The target area conformity index (CI), homogeneity index (HI), and affected lung radiation acceptance (V20, V5) of patients with positioning holes were better than those of patients without positioning holes (P<0.05). There was no significant difference in target area coverage of prescription dose, cardiac dose D_mean and spinal cord dose D_max between two groups (P>0.05).

Conclusions The skin fit, dosimetric indexes of patient target area and organs at risk of 3d-printed bolus with positioning holes were superior to those without positioning holes, showing significant advantages in clinical applications.