Accuracy of 3D printing template-assisted CT-guided radioactive iodine-125 seed implantation for peripheral locally recurrent rectal cancer: A retrospective study

Abstract

Objective

This study aimed to investigate the accuracy of needle insertion and dosimetric parameters in three-dimensional printing template (3D-PT)-assisted computed tomography (CT)-guided radioactive iodine-125 (¹²⁵I) seed implantation (RISI) for the treatment of peripheral locally recurrent rectal cancer (pLRRC).

Materials and methods

A total of 37 patients with pLRRC who underwent 3D-assisted CT-guided RISI treatment at Peking University Third Hospital between January 2016 and November 2019 were included in this study. All patients underwent preoperative assessment, CT simulation positioning, preoperative plan design, 3D template printing, 3D template reduction, needle and seed implantation, postoperative dosimetry evaluation, postoperative care, and regular follow-up. The preoperative and postoperative needle position, angle, and tip distance were compared. The dosimetric parameters, including D90 (the dose to 90% of the target volume), D100, V100 (the volume receives 100% of the prescribed dose), V150, V200, conformal index (CI), external index (EI), and homogeneity index (HI), were compared among preoperative plan, intraoperative plan, and postoperative plan. The perioperative complications were assessed.

Results

The total number of needles was 595. The depths of needle insertion in preoperative and intraoperative plans were 109.87 ± 1.33 mm and 108.46 ± 1.26 mm, respectively, with no significant difference (p > 0.05). The angles of needle insertion in preoperative and intraoperative plans were (93.55 ± 2.05)° and (92.04 ± 1.99)°, respectively, with no significant difference (p > 0.05). The average deviation of the needle insertion distance was 1.99 ± 0.08 mm. There were no differences in preoperative, intraoperative, and postoperative parameters, including D90, D100, V100, V150, V200, CI, EI, and HI. All patients were closely followed up during the perioperative period (from seven days before surgery to seven days after surgery). No patients experienced severe perioperative complications. A total of eight patients (21.6%) experienced grade 1−2 complications. Among all patients, six individuals (16.2%) experienced pain, one patient (2.7%) had a fever, and one patient (2.7%) suffered from a hemorrhage. All patients recovered after conservative treatment.

Conclusion

The needle insertion in 3D-PT-assisted CT-guided RISI showed good accuracy for treating pLRRC.