125I brachytherapy seeds implantation for an inoperable large retroperitoneal leiomyosarcoma

Retroperitoneal leiomyosarcoma is relatively uncommon. Leiomyosarcoma has accounted for about 5%-10% of soft-tissue sarcoma, and 1/2–2/3 of the primary lesions were retroperitoneal, with a cumulative 5-year survival rate of only 35%.Leiomyosarcoma is one kind of soft-tissue sarcoma with the lowest survival rates due to the invasive growth, difficult treatment, and poor prognosis.The present study reported a case of a 78-year-old male diagnosed as left retroperitoneal leiomyosarcoma, who had received three operations. Computed tomography (CT) demonstrated a mass of approximately 12.9 cm × 6.9 cm × 6.6 cm in his retroperitoneal region. The Eastern cooperative oncology group and numerical rating scale scores of pain were 1 and 5, respectively. Multiple treatment strategies were administered, including the application of drainage and125I seed implantation. A total of 90125I seeds were implanted into the tumor through repetitious operations, with 30 seeds each time. Treatment planning system was involved to calculate the source distribution.125I seeds with the activity of 0.5 mCi were implanted under the guidance of CT, and dosimetric verification was performed after the operation. D90 (90% minimum prescription dose received by target volume) was 40 Gy. Follow-up was performed after 6 months, and complete response was achieved in the local lesions. However, there was no evidence-based treatment currently and the majority of our knowledge was based on results from case reports, thus further studies would be required

Preliminary investigation of computed tomography-guided iodine-125 seed implantation treatment efficacy in patients with iliac lymph nodes metastases

Objectives: The objective of this study is to assess the technical feasibility, safety, and efficacy of computed tomography (CT)-guided iodine-125 (125 I) seed implantation to treat malignant iliac lymph node metastases. Materials and Methods: In this retrospective study, 11 patients with a total of 11 iliac lymph node metastases were implanted with 125 I seeds (14.8–25.9 MBq) under CT-guidance, both the seed quantity and distribution were measured with a computerized treatment planning system. Treatment effects and adverse events were evaluated. Results: 125 I seeds were successfully implanted in all patients, and the minimum peripheral dose of seeds was ranged from 30 to 110 Gy (median of 75 Gy). The median follow-up period was 11 months (ranged 3–39 months). Follow-up at 2 months after implantation revealed partial response in eight patients, stable disease in two patients, and progressive disease in one patient. The overall response rate and the local tumor control rate at 2 months were 72.73% and 90.91%, respectively. The rates of refractory pain and leg edema relief were 100% and 50% within 2 weeks after treatment, respectively. Survival rate at 1 year was 45.45%. No peri-interventional mortality or major complication was observed. Conclusion: 125 I seed implantation was a safe and effective technique for minimally invasive treatment for iliac lymph node malignant metastasis

Precision dose measurement of 125I seed in solid water through SPECT/CT detecting

Purpose: The aim of the study is to study the feasibility of gamma-ray-detection-based precision dose measurement of 125I seed brachytherapy in solid water. Materials and Methods: Seven group 125I seeds with different activities were put into a hole in the center of solid water individually. Each group had ten seeds, and the seed activity ranged from 1.48 × 107 Bq to 3.7 × 107 Bq. Single-photon emission computed tomography/computed tomography (SPECT/CT) was used to scan the seeds perpendicular to the long axis of the seed, with a slice thickness of 3.75 mm. The radioactive count values (x) of the radioactive concentration around the seeds were collected at a distance of 1–15 mm from the center of the seeds, while the corresponding doses (Y) (Gy) were calculated. SPSS 18.0 was used to analyze the relationship between the count value and the dose. Results: With the same seed activity, the count values became smaller according to the distance from the center of the seeds. The count values at the same point had an increasing trend according to the activity. This is similar to the doses calculated at the same point. There was an exponential relationship between the dose around the 125I seeds, and the radioactive count value detected by SPECT/CT. Correlative curves between the dose and radioactive count value detected by SPECT/CT of different-activity 125I seeds were fitted. The formulas of the dose and radioactive count with different seed activity were in the form of Y = b0 (b1)x. The constant b0 ranged from 1.48 to 3.93, according to the seed activity, while b1 was 1.006 for every seed's activity. Conclusion: The count value around the 125I seed can be detected accurately by SPECT/CT, and then can be quantified. This study provided useful experiment data for the precision measurement of 125I seed implantation. Radiation detection-based dose measurement may become a new noninvasive technology for the dynamic dosimetry verification method after brachytherapy