RÉSUMÉ
Objective:To explore the method of developing a canal-shaped implant template using a combined automatic pre-planning and 3D printing technology, and assess its impact on dose and efficacy improvement.Methods:Retrospective analysis of 15 patients with advanced cervical cancer admitted to the Affiliated Cancer Hospital of Guangxi Medical University from September 2020 to September 2022 was performed. Patients had characteristics such as vaginal stump recurrence, tumor eccentric growth, and previous hysterotomy, etc. Three-dimensional images were obtained by CT scan after automatic pre-planning. The PMT 3D software was used to analyze digital imaging and communications in medicine (DICOM) radiotherapy data, capture the coordinates of the pre-planned stay points to establish the implant channel, and generate the size and shape of the canal-shaped implant template based on patients' physiological structure. Dosimetric parameters, such as conformity index (CI), were evaluated. The changes of tumor size before and after treatment were analyzed by paired t-test. Results:Fifteen patients were treated with the canal-shaped implant template. The CI was 0.74±0.26, the total radiation dose (HR-CTV) D 90% (EQD 2, α/β=10) was (85.5±6.8) Gy, and the D 2 cm3 (EQD 2, α/β=3)for bladder, rectum, small intestine, and colon were (72.2±4.2), (65.8±6.1), (65.2±4.4), and (69.8±3.7) Gy, respectively, meeting clinical needs. After the treatment, the tumor volume was significantly decreased. The template had a good fit with the vaginal cavity, and a small amount of air gap on the sidewall did not affect the dose. Non-parallel needle insertion increased the utilization of the cavity space and implant needles. Conclusion:The method of developing the canal-shaped implant template using automatic pre-planning and 3D printing technology is efficient and effective, meets the requirements of modern precise radiotherapy, and has practical clinical value.