Dosimetry evaluation of three-dimensional-printing template guided radioactive seeds implantation assisted by navigation system in malignant tumors / 中华核医学与分子影像杂志

ABSTRACT

Objective:To compare the difference of preoperative and postoperative plans of navigation-assisted three-dimensional (3D)-printing template combined with CT-guided radioactive 125I seeds implantation for malignant tumors, and verify preliminarily the plan quality of optical navigation-assisted seeds implantation. Methods:From December 2018 to November 2019, a total of 20 patients (10 males, 10 females, median age 60.5 years) with malignant tumors received navigation-assisted 3D-printing template combined with CT-guided radioactive 125I seeds implantation in Peking University Third Hospital. Eight cases were implanted in the head and neck, 1 case in the chest wall, 9 cases in the pelvis and 2 cases in the paravertebral and/or retroperitoneal region. The median prescription dose was 150 Gy. The data in the preoperative and postoperative plans was compared, including seeds number, needles number, and some dosimetry parameters. Dosimetry parameters including dose delivered to 90% gross tumor volume (GTV) ( D90), percentage of GTV received 100%, 150%, and 200% of the prescribed dose ( V100, V150, V200), minimum peripheral dose (MPD), conformal index (CI), external index (EI), homogeneity index (HI) of target volume, and 2 cm 3 range of spinal cord receiving dose ( D2 cm 3). Paired t test and Wilcoxon signed rank test were used to analyze the data. Results:The needles number of preoperative and postoperative plans was the same (both 12 (9, 19)), and the seeds number of postoperative plan was more than preoperative plan with no significant difference (51(35, 68) vs 49(35, 63); z=1.859, P>0.05). The MPD of postoperative plans was higher than preoperative plans ((80.52±14.89) vs (67.22±20.56) Gy, t=-3.769, P=0.001). There were no significant differences in other dosimetry parameters between the two plans ( t values -0.533, -0.423, z values from -0.849 to 1.416, all P>0.05). Postoperative dose quality assessment was excellent in 17 cases (17/20), good in 2 cases (2/20) and middle in 1 case (1/20). Conclusions:The quality of the implantation is good under the guidance of combined mode. The actual target dose after operation can meet the requirements of preoperative planning.