Objective:To verify the accuracy and feasibility of radioactive 125I seed implantation assisted by an optical navigation system and a 3D-printing non-coplanar template in the treatment of recurrent head and neck cancers. Methods:A total of 12 patients with recurrent head and neck cancer treated with radioactive 125I seed implantation assisted by an optical navigation system and 3D-printing non-coplanar template were enrolled from Dec 2018 to Dec 2019.The pre-plan and post-implant implantation needle number and implanted seed number were recorded.Meanwhile, their dosimetric parameters were compared, including D90, minimum peripheral dose (MPD), V100, V150, V200, conformity index (CI), external index (EI), and the homogeneity index (HI) of the target volume. Results:The median lesion volume was 31.5 cm 3, the median number of seeds was 61.5, and the median prescription dose was 130 Gy.The means of the pre-plan D90, MPD, V100, V150 and V200 were 134.2, 64.6, 93.3, 75.3 and 39.3 Gy, respectively, while those of post-implant D90, MPD, V100, V150, and V200 were 146.7, 68.94, 97.47, 80.40 and 48.30 Gy, respectively, with no statistically significant difference ( P>0.05). Meanwhile, there was no statistically significant difference between the pre-plan and post-implantation needle number, implanted seed number, CI, HI, and EI ( P>0.05). In terms of postoperative dose quality assessment, eight cases were rated excellent (66.6%) and four cases were rated good (33.3%). Conclusions:Radioactive 125I seed implantation assisted by an optical navigation system and 3D-printing non-coplanar template can be accurately performed in the treatment of recurrent head and neck cancer, with good consistency between pre-plan and post-implant dosimetric parameters and thus of prospective potential in clinical application.

Prolonged instances of arrhythmia may not only exacerbate original heart diseases,but also cause hemodynamic disorders and even sudden death.Catheter ablation,which utilizes a catheter to directly destroy the underlying arrhythmia substrate,has become the main treatment.Recent advances have enabled noninvasive delivery of precise arrhythmia radioablation with electrophysiology-guided stereotactic body radiation therapy(SBRT),termed stereotactic arrhythmia radioablation(STAR).The progress of STAR was reviewed in this paper.

Objective:To investigate the accuracy and feasibility of 3D-printing individualized template-guided and CT-guided 192Ir interstitial brachytherapy in the central recurrent gynecologic tumors by comparing pre-plan and intraoperative physical dosimetric parameters. Methods:This study involved 38 patients with central recurrent gynecologic tumors who underwent 3D printing individual template (3D-PIT)-assisted and CT-guided 192Ir interstitial brachytherapy in the Department of Radiation Oncology of the Peking University Third Hospital from Jan 2018 to Dec 2019.The prescription doses for the target tumor areas were 10-36 Gy to be delivered at 5-6 Gy/fraction for 2-6 fractions.The pre-plan and intraoperative dosimetric parameters were compared, including the minimum prescription doses delivered to 90% and 100% of target volume( D90, D100)and the mean percentage of volume receiving 100% of the prescription doses ( V100). Meanwhile, the doses delivered to 2 cm 3 ( D2 cm 3) of organs at risk (bladders, rectums, and colons) were analyzed.The quality parameters of the brachytherapy were studied, including conformity index (CI), homogeneity index (HI), and external index (EI) of the target volume.Perioperative complications were also observed. Results:A total of 194 treatments were included.During the treatment, 5-13 (median 6) needles were inserted, with a prescription dose of 5-6 Gy per fraction.There were no statistical differences between pre-plan and intraoperative D90, D100, V100, CI, HI, and EI as well as the D2 cm 3 of bladders and colons at risk ( P>0.05). In contrast, for the D2 cm 3 of rectums, the intraoperative dose was slightly higher than the pre-plan dose, showing a statistical difference ( t=-0.335, P=0.027). Conclusions:The 3D-PIT-assisted and CT-guided 192Ir interstitial brachytherapy at a high dose rate is accurate and feasible in the treatment of recurrent gynecologic tumors, meeting the pre-plan dose requirement.