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Dosimetric characteristics of 125I-seed-loaded portal stentsObjective: To evaluate the dosimetric characteristics of of 125I-seed-loaded portal stents and provide the dosimetry theory for the clinical application.Methods: The portal vein seed-loaded-stent system was designed as two separate parts that were coaxially deployed,consisting of an outer seed–loaded stent and an inner self-expandable nitinol commercial stent.The most frequently used size at a diameter of 12 mm and a length of 60 mm,which could load 16 type 6711 125 I seeds,is chosed in this study.A reference point is defined at 5 mm away from the projected center of seed array on a mid-cross-section plane.The prescription dose is 145 Gy at this reference point.Monte Carlo(MC)N-Particle transport code version 6.1(MCNP6.1)and treatment planning system(TPS)was respectively used and compared to perform the dose calculation of 4-array,6-array,and 8-array stent on radial dose distribution,angular uniformity.Results: Radial dose distributions of ?=0°,30° and 45° for five different Z for 4-array seed-loaded-stent system are obtained.The radial doses from MC and TPS were in a good agreement.When the angle and longitudinal positions are 0° and Z=5,15,respectively,the dose near the surface of the seeds were about 10.5 times higher than the dose at the reference point.When the longitudinal position Z is 20 mm,the doses at d=5 mm for all three different angles were 51-55% prescription dose.While the doses at d=5 from Z=0 to 5 were over than 94% prescription dose for all three angles,large drops of dose were observed for Z=15 at ?=30°and 45°(79-81% prescription dose).The radial doses at d=20 mm were decreased down to 20% prescription dose.For all three configurations,the 100% isodose curves at Z=0 and 5 were observed to cover the circle sufficiently.However,particularly for 4-array system at Z=15,the 100% isodose line showed that cold spots existed depending on the angle.Compared with 4-or 6-array,8-array seed-loaded-stent system showed better dose uniformity.Conclusions: Dosimetric properties of current 4-array seed-loaded-stent system were assessed by MC simulation and TPS calculation with proper dose uniformity.Eight-array seed-loaded-stent system was suggested to improve the dose uniformity.PART ? Feasibility and safety of 125I-seed-loaded portal stent placement in normal beaglesObjective: To assess the feasibility and safety of the 125I-seed-loaded portal stents in placement the portal vein of healthy beagles.Methods: A total of 20 healthy beagle dogs were randomly assigned into 4 groups(5 in each group),namely that 15 beagle dogs in three experimental groups received portal stenting with seed activity of 11.1 MBq,22.2 MBq,and 33.3 MBq while 5 received portal stent without seed as a blank control group.This experiment was approved by the experimental animal ethics committee of Southeast University.Follow-up was performed at the 1st,15 th,30th,60 th,and 120 th days after stent,including blood biochemical test,color Doppler sonography,and CT scans.Pathological tissues were obtained from sacrificed beagle dogs on the 120 th day.Results: All the 125I-seed-loaded portal stents in the experimental group and conventional portal stents in the control group were successfully deployed into the targeted portal vein in all beagles.Migration of seed or stent,fall-of of seed,and metallic wire twisting were not observed during the procedure.After the stent was released,immediate portal vein angiography showed that the blood flow was good.Differences of blood biochemical parameters and portal vein flow volume between pre-and post stent placement were not significant(P>0.05).No stent displacement and particle loss were found on CT scans after 120 days.After stent placement,differences of blood biochemical parameters and portal vein flow volume between 4 groups were not significant(P>0.05).No perforation of portal vein and necrosis of surrounding tissue were observed.Pathological tissues revealed that the stents were surrounded by fibrous tissues and a few inflammatory cells without significant differences among all groups.Conclusions: It is feasible and safe to implant the 125I-seed-loaded portal stents in the portal vein of healthy beagles.PART ? Feasibility and safety of 125I-seed-loaded portal stent placement for portal vein tumor thrombosis caused by hepatocellular carcinomaObjective: To assess feasibility,safety,and preliminary efficacy of 125I-seed-loaded portal stent placement for portal vein tumor thrombosis(PVTT)in patients with hepatocellular carcinoma(HCC).Methods: This prospective,single center study was approved by the ethics committee of Zhong-Da Hospital,Southeast University.Between October 2012 and September 2015,25 of 40 patients(mean age of 55.5 y)with PVTT caused by HCC were recruited.Liver function was classified as Child-Pugh class A in 15 patients(60%)and class B in 10 patients(40%).The Eastern Cooperative Oncology Group performance status score was 0 in 3 patients(12%),1 in 13 patients(52%),and 2 in 9 patients(36%).Transarterial chemoembolization was performed after stent placement.Outcomes were measured in terms of technical success,complications,stent patency,and overall survival.Results: The technical success rate was 92.0%(23/25).The mean portal vein flow volume increased from 750.0 ± 643.0 m L/min to 1534.7 ± 494.8 m L/min(P<0.001)on day 7 after stent placement.Overall,10 adverse events related to portal vein stent placement or radiation therapy were recorded in 8 patients,all of which were controlled with symptomatic therapy with several days.No severe complications were observed.Median stent patency period was 8.0 months.The 3-,6-,9-,and 12-month cumulative stent patency rates were 84.1%,66.1%,54.1%,and 37.1%,respectively.A total of 65 cycles of transarterial chemoembolization were performed with a mean of 2.8 cycles per patient.Median survival was 12.5 months.The 3-,6-,9-,and 12-month cumulative survival rates were 86.4%,81.6%,69.2%,and 54.5%,respectively.Conclusions: Placement of a 125I-seed-loaded portal stent appears feasible and safe and may prolong the patency of the portal vein and overall survial of patients.PART ? 125I-seed-loaded portal stent placement plus transarterial chemoembolization for hepatocellular carcinoma with portal vein tumor thrombosis: a retrospective controlled studyObjective: To investigate efficacy of transarterial chemoembolization(TACE)in combination with 125I-seed-loaded portal stent placement in patients with hepatocellular carcinoma(HCC)and portal vein tumor thrombosis(PVTT).Methods: From January 2011 to December 2016,patients with HCC and PVTT who underwent TACE combined with 125I-seed-loaded stent placement(Group A)or TACE monotherapy(Group B)at Zhong-Da Hospital,Southeast University were retrospectively reviewed.The eligibility criteria included the following:(a)newly diagnosed type II or III PVTT,(b)Child-Pugh classification grade A or B,(c)Eastern Cooperative Oncology Group performance status score 0-2.The exclusion criteria were as follows:(a)type I or IV PVTT,(b)received sorafenib,systemic chemotherapy,or external radiotherapy,(c)suffered from another malignancy,(d)with an incomplete medical record.Overall survival,tumor responses,adverse events,and underlying prognostic factors for survival were analyzed.Results: A total of 126 patients from 231 candidates were included in this study: 44(34.9%)in the Group A and 82(65.1%)in the Group B.The survival in the Group A was significantly longer than that in the Group B(median survival 14.5 vs.6.3 months,P <0.001).The cumulative survival rate at 3-,6-and 12 months was 95.4 % to 86.4%,85.1% to 55.1%,and 63.9% to 9.1% in the Group A and Group B,respectively(P<0.001).Disease control rate against liver parenchymal tumor was noted in 81.8% cases(36/44)in the Group A and 58.8% cases(47/80)in the Group B(P=0.009),respectively.Although the incidence of most adverse events between the two groups were not significantly different,the percentage of patients who experienced acute hepatic decompensation was lower in the Group A than in the Group B(P=0.010).Multivariate analysis revealed that AFP level,arterial-portal shunt,tumor response,and treatment group were the independent prognostic factor for survival in the two groups.Conclusions: TACE in combination with 125I-seed-loaded stent placement could decrease the incidence of acute liver failure,improve the tumor control rate,and prolong the overall survival in HCC and PVTT than TACE monotherapy.PART ? Placement of 125I-seed-loaded biliary stent for unresectable malignant biliary obstruction: a multicenter randomized conrolled trialObjective: Placement of 125I-seed-loaded biliary stent has been demonstrated to offer longer patency and survival than an uncovered self-expandable metallic stent(SEMS)in patients with unresectable malignant biliary obstruction(MBO).We aim to further assess the efficacy of a 125I-seed-loaded biliary stent compared to an uncovered SEMS in those patients.Methods: We performed a randomized,open-label trial of participants with unresectable MBO at 20 centers in China.A total of 328 patients fron 375 candidates were allocated in parallel to the irradiation stent group(ISG)or the uncovered SEMS group(USG).Endpoints included stent patency(primary),technical success,relief of jaundice,overall survival,and complications.Results: Stent restenosis was observed in 21%(34/164)of patients in the ISG and 34%(56/164)in the USG,respectively.The first quartile stent patency time(when 25% of the patients experienced stent restenosis)was 212 days for the ISG and 104 days for the USG.ISG was significantly associated with a decrease in the rate of stent restenosis(9% vs.15% at 90 days;16% vs.27% at 180 days;21% vs.33% at 360 days;P=0.010).Technical success achieved 93%(152/164)in the ISG and 95%(155/164)in the USG(P=0.499).Relief of jaundice was recorded of 85%(139/164)in the ISG versus 80%(132/164)in the USG(P=0.308).Patients in the ISG obtained longer survival time(median 202 days vs.140 days;P=0.020).The incidence of severe complications was comparable(8.5% v 7.9%;P=0.841).Conclusions: Insertion of 125I-seed-loaded biliary stents instead of uncovered SEMS could decrease rate of restenosis,improve patency,and overall survival in unresectable MBO. |
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