ABSTRACT
Objective To explore the dosimetric effects of the same number and activity of radioactive 125I seeds in different plane arrangements. Methods Simulated 9 distribution modes using 9 125I seeds were designed by three- dimensional treatment planning system (3D- TPS), and the isodose curves of 60 Gy, 80Gy, 130 Gy, 145 Gy and 200 Gy were obtained. The areas enclosed by the isodose curves, the longer and shorter radius of these isodose curves and the medical cost per unit area were calculated with the professional image analysis software. Results Obvious differences in areas enclosed by the isodose curves, the longer and shorter radius of these isodose curves and the medical cost per unit area existed between each other among the nine different distribution modes of 9 125I seeds. The distribution modes that had the maximum areas enclosed by 60 Gy, 80 Gy, 130 Gy, 145 Gy and 200 Gy isodose curves were x1.5y1.5, x1y1.5, x1y1, x1y1 and x0.5y1, respectively, with the corresponding areas of 1 583.86 mm2, 1 146.03 mm2, 768.30 mm2, 621.85 mm2 and 480.97 mm2, respectively. Conclusion The peripheral dose and the therapeutic efficacy are significantly influenced by the arrangement of 125I seeds when the same number and activity of the seeds are used. The dose distributions are more homogeneous when the maximum areas enclosed by the isodose curves are obtained.
ABSTRACT
Objective To investigate the safety and effectiveness of radioactive 125I seed implantation in treating recurrent cervical lymphatic metastases after radiotherapy. Methods During the period from Aug. 2011 to July 2012, 17 patients with recurrent cervical lymphatic metastases who had received radiotherapy before were admitted to authors’ hospital. The clinical data were retrospectively analyzed. A total of 23 metastatic lymph nodes were detected in the 17 patients. Brachytherapy treatment planning system (TPS) was used to formulate the number, activity and distribution of radioactive 125I seeds. The radioactive activity was 0.3 - 0.8 mCi (1.30 × 107- 2.96 × 107 Bq), and the matched peripheral dose (MPD) was 60 - 120 Gy. Guided by ultrasound and CT radioactive 125I seeds were implanted under local anesthesia. CT scanning was performed within 24 hours after the procedure. Postoperative D90 was (81.4 ± 2.1) Gy. CT examination was employed every two months to determine the tumor size and to record the complications. Results All patients were followed up for 6 months. The 6-month local control rate was 65.2%. The control rates (CR+PR) for4 cm (n=13) lymph nodes were 90%and 46%respectively, the difference between the two was statistically significant (P = 0.038). No significant difference existed between the control rate (CR + PR) and the un-control rate (SD + PD) for each lymph node group at cervical Ⅰ, Ⅱ, Ⅲ and Ⅴ grade Ⅱ was seen in 8 cases and grade Ⅰ in 7 cases. No severe complications occurred. Conclusion For the treatment of recurrent cervical lymphatic metastases after radiotherapy, radioactive 125I seed implantation is effective and mini-invasive with fewer complications. This technique is more suitable for < 4 cm solitary metastatic lymph node with clear border.
ABSTRACT
Objective To study the effective dose and precaution time of the irradiation of the close contact from the radiators who underwent implantation of radioactive 125Ⅰ seeds so as to guide scientifically people how to avoid radiation damage.Methods Twenty patients with different types of cancer underwent implantation of radioactive 125Ⅰ seeds with the median value of implantation depth of 2.16 cm.Within 24hs after the operations the dose rates 30 cm and 100 cm from the skin were measured with pocket-size radiometer so as to imitate the situations of the close contacts.The effective doses and precaution times of different persons were calculated according to relevant formula.Results The dose rate a person received at the same time points (1,54,78,and 109 d,respectively) decreased along with the increase of the distance from the skin (t =5.962,5.961,5.961,5.962,P ＜ 0.05).and the dose rate a person received at the same distance from the skin decreased along with the extension of time (30 cm:t =6.236,6.236,6.235,P＜0.05;100 cm:t=7.310,7.315,7.314,P＜0.05).At different time points,the dose rates at 30 cm distance point were all significant higher than those at the 100 cm point (P ＜0.05).The adult living together,minors and pregnant women sharing the room,colleagues,adults who slept together with the patients began to reach the 50％ dose constraint values 0,54,78 and 109 days after the operation.Conclusions After their precaution time,it's safe to contact with the patients for the groups;otherwise,it's necessary to take some protect works within the precaution time.