Application value of personalized 3D printing vaginal model for the Image-guided adaptive brachytherapy of cervical cancer

Objective: To explore the application value of using 3-dimensional (3D) printing (3DP) technology to create individualized vaginal molds for brachytherapy (BT) in high-dose-rate 3D cervical cancer through reverse engineering of needle placement.

Methods: Prospectively, 11 patients with cervical cancer were treated with 3DP-intracavitary/interstitial (IC/IS) BT using 3DP to create individualized vaginal molds. All patients were performed BT after completion of external beam radiotherapy (EBRT). Each patient was treated with BT 5 times, the prescription dose was 600 cGy/F, which was performed once or twice a week, 2 of them were freehand IC/IS BT, and 3 were 3DP-IC/IS BT. The relevant planning parameters (bladder, rectum, sigmoid colon, and small intestine) and target conformity index (CI) for high-risk clinical target volume (HR-CTV) and organs at risk (OARs) were compared between the groups.

Results: There were significant advantages in the 3DP-IC/IS BT group compared with the freehand IC/IS BT group: HR-CTV D₉₀ (629.40±19.34 vs. 613.03±15.93 cGy, p=0.002), D₉₅ (580.74±18.31 vs. 567.44±23.94 cGy, p=0.032), bladder D_2cc (431.11±23.27 vs. 458.07±23.27 cGy, p<0.001), bladder D_1cc and bladder D_0.1cc. There was no statistically significant difference (p>0.05) between the 2 groups in rectal D_2cc (352.30±42.42 vs. 361.29±42.42 cGy, p=0.470), sigmoid colon D_2cc (236.73±78.95 vs. 246.50±58.17 cGy, p=0.621), CI (0.79±0.04 vs. 0.79±0.039 p=0.773), HR-CTV V₁₀₀, V₂₀₀, D₉₈, D₁₀₀ and other OARs parameters (p>0.05).

Conclusion: Compared with IC/IS BT, 3DP-IC/IS BT has apparent advantages with simple operation and high safety. In addition, individualized mold helps to improve the tumor target area's radiation dose while meeting the dose-limiting requirements for organs at risk and reduces the clinical proficiency requirements for operating physicians.