Application of canal-shaped implant template in brachytherapy for cervical cancer / 中华放射肿瘤学杂志

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.

Material Extrusion Based Fabrication of Surgical Implant Template and Accuracy Analysis.

An implant template with great precision is significantly critical for clinical application. Currently, the application of an immediate implant remains limited by the deviations between the planned and actual achieved positions and long periods required for preparation of implant templates. Material Extrusion (MEX), as one kind of 3D printing method, is well known for its low cost and easy operation. However, the accuracy of the implant template printed by MEX has not been fully researched. To investigate the accuracy and feasibility of in vitro computer-guided surgery assisted with a MEX printed template, unidentified plaster samples missing a maxillary molar are digitalized. Mimics software (Materialise, Leuven, Belgium) is used for preoperative design. Surgical templates are fabricated by a MEX 3D printer (Lingtong III, Beijing SHINO, Beijing, China). Postoperative CBCT data are obtained after surgical template placement. The differences in positions of X, Y, Z, and dXYZ as well as angulations between the placed and the designed template are measured on labiolingual and mesiodistal planes. The deviations of the planned and the actual outcome in each dimension are observed and analyzed. Data from different samples indicate that the mean deviation of the angle measures approximately 3.640°. For position deviation, the maximum deviation is found in the z-direction and the mean deviation is about 0.365 ± 0.136 mm. The mean deviation of space Euclidean distance dXYZ is approximately 0.537 ± 0.123 mm. Implant templates fabricated by MEX present a relatively high accuracy for tooth-supported guide implantation.

Accuracy of a chairside fused deposition modeling 3D-printed single-tooth surgical template for implant placement: An in vitro comparison with a light cured template.

PURPOSE: To compare the accuracy of a chairside fused deposition modeling (FDM) 3D-printed surgical template with that of a light-cured template for implant placement. MATERIALS AND METHODS: Twenty standard mandibular resin models with missing teeth 36 and 46 were selected. Surgical templates were fabricated using a chairside FDM 3D-printer (test group) or a light-curing 3D printer (control group) (n = 20/group). Forty implants were placed by a clinician blinded to group allocation. The angular, 3D, mesiodistal, buccolingual, and apicocoronal deviations at the implant base and tip between preoperative design and postoperative implant position were recorded. RESULTS: The mean angular (test vs control groups: 3.22° ± 1.55° vs 2.74° ± 1.24°, p = 0.343) and 3D deviations at the implant base (test vs control groups: 0.41 ± 0.13 mm vs 0.35 ± 0.11 mm, p = 0.127) and tip (test vs control groups: 0.91 ± 0.34 mm vs 0.75 ± 0.28 mm, p = 0.150) were similar. The mesiodistal, buccolingual, and apicocoronal deviations at the implant base and tip also did not differ significantly between groups (p > 0.05). CONCLUSIONS: For single tooth gap indications, implant placement with an FDM 3D-printed surgical template was as accurate as that with a light-cured template, and more efficient.