放射性球囊内气泡对血管组织剂量分布的影响

目的：计算放射性球囊治疗冠状动脉再狭窄时球囊内气泡对血管的剂量分布影响。方法：采用Prestwich的剂量点核函数计算球囊周围的剂量分布，计算体积为0.02mL的气泡位于球囊壁中心和边缘两种情况下对球囊周围组织的剂量分布影响，并与无气泡的液体球囊比较。结果：气泡在球囊壁中心时，影响范围为4mm,球囊两侧的剂量不均匀最大可达38％；在边缘时，影响范围为6mm，剂量不均匀达47％。结论：球囊内气泡对血管组织的剂量分布有影响。     

32P液体球囊在血管组织中的剂量分布

目的　研究放射性液体球囊治疗冠状动脉再狭窄时在血管组织内的剂量分布。方法　用模拟实验和理论计算两种方法估算剂量分布。结果　模拟测量和理论计算的剂量平均值分别为 9 0 ,9 7mGy·min-1 ,两者差异为 7 8%。结论　3 2 P液体球囊的剂量分布在轴向上均匀 ,在径向上快速衰减     

放射性充液球囊的剂量学研究

单纯经皮冠脉血管成形术 (ＰＴＣＡ)最大的缺陷是术后再狭窄 ,发生率高达 30 %～ 5 0 %。血管内放射治疗是近年发展起来的防治再狭窄的有效手段。目前其照射方法大致有以下几种 :放射性导丝、放射性液体充盈球囊和放射性支架。放射性液体充盈球囊是将放射性液体注入球囊 ,达到局部照射的目的。放射性液体球囊容易使用 ,并最适合导管室的操作步骤 ,它易进入弯曲血管的中远段 ,具有均匀精确的剂量分布 ,很少受血管大小和形态变异的影响。缺点是有可能发生放射性泄漏 ,但其迅速的代谢和排泄对病人和操作人员影响较小。一、材料和方法1 放射源剂…     

血管内近距离放射治疗剂量影响因素的研究

目的　研究32 P球囊预防血管再狭窄的影响因素。方法　采用组织等效血管和热释光剂量学方法。结果　 2 5mm× 2 0mm空球囊内残留32 P对血管壁造成的剂量影响是 0 92Gy min。当球囊内导管偏离中心时 ,球囊外表面的吸收剂量将降低 2 0 %。气泡位置处的吸收剂量比球囊外表面平均吸收剂量低约 30 %。结论　32 P球囊表面轴向剂量分布较均匀 ,但径向吸收剂量随距离增加迅速减少。血管内近距离放射治疗有很好的临床应用前景。     

β核素球囊预防血管再狭窄的临床剂量估算

目的 探讨核素球囊内照射血管内的吸收剂量分布规律。方法 ①依据吸收剂量点核函数模拟计算^90Y、^186Re、^32P灌注球囊时血管组织中的吸收剂量率分布；②用非线性最小二乘法对吸收剂量率随球囊外径及组织深度的变化进行曲线拟合，并由此导出便于临床使用的经验公式。结果 球囊中吸收剂量率峰值出现在血管腔内球囊中，血管表面位于吸收剂量率曲线的拐点处，血管壁及周围组织中的吸收剂量率以近双指数方式下降。吸收剂量、持续照射时间、初始放射性浓度、组织深度及球囊外半径间的关系可用一经验公式表达。结论 血管组织中的β核素吸收剂量分布呈快速下降。该经验公式具有实用价值。     

32P液体球囊在血管内吸收剂量的研究

目的　研究32 P球囊在血管内的剂量分布。方法　用肌肉等效材料代替血管壁 ,采用热释光剂量学方法模拟测量靶血管轴向和径向吸收剂量率分布 ,并对相关影响因素 (球囊内压力 ,气泡 )进行了研究。结果　 3 0mm× 2 0mm 32 P球囊 ,活度为 92MBq时 ,血管表面平均吸收剂量率为0 48Gy min ,在径向 0 4mm处为 0 2 2Gy min。结论　血管壁表面剂量分布较均匀 ,径向剂量随距离迅速衰减 ,但存在诸多影响因素。     

模拟测定103Pd放射性支架在血管中的剂量分布

目的 测定血管内^103Pd放射性支架的剂量分布。方法 采用肌肉组织等效材料代替血管壁，用热释光剂量计模拟测量血管内的剂量分布。结果 当支架活度为9．8MBq时，支架表面累积吸收剂量为9．8Gy(17d)。^103Pd支架表面的剂量分布随径向距离增加而迅速减少，在支架表面径向距离0．4mm处80％的剂量被血管壁吸收。结论 血管内^103Pd支架对血管周围的器官和组织无明显损害。     

泪道放射性探针制备及其剂量学分布

目的 制备泪道放射性探针并探讨其近距离照射治疗的有效剂量范围及安全性。方法 ^125Ⅰ粒子内置热塑管中制成泪道放射性探针，对其进行温度、压力、浸泡、冲击试验，应用热释光法测量其在体模及蜡模中的剂量学分布。结果 泪道放射性探针温度、压力、浸泡实验结果示探针无变形，表面放射性污染〈185Bq。冲击实验结果示探针压扁变形，但表面放射性污染〈185Bq。在蜡模及人体等效模型中剂量学测量结果示：在1～12mm范围内，与探针距离每增加1mm单位时间内的吸收剂量差异有显著性（P〈0、05）；在12～40mm范围内，相邻测量组间的吸收剂量差异无显著性（P〉0、05）。结论 采用泪道放射性探针近距离照射治疗，在符合相关安全标准的同时，泪道狭窄处组织可获得有效治疗剂量，其有望成为治疗泪道再狭窄的新方法。     

^192Ir高线量率血管腔内照射对抑制兔血管平滑肌细胞增殖及新生内膜过度增生的研究

目的 研究^192I搞线量率血管腔内照射对用切割球囊导管行经皮血管腔内成形术（PTA）后的日本白兔髂动脉平滑肌细胞增殖抑制的经时反应和效果。方法 20只日本白兔经左侧颈总动脉放置切割球囊导管行髂动脉PTA术，随机于一侧髂动脉施行12Gy剂量的血管腔内照射，非照射侧作为对照侧。实验动物于术后1、2、3、4、8及12周处死。根据新生内膜的形成情况，血管成形术后接受血管腔内照射的血管段按时间分为3组：即1周组5只、2－4周组9只、8－12周组6只。随后对标本进行了组织病理、形态学测量和免疫组织化学分析。结果 1周时，与照射侧比较，对照侧血管段创口修复处可明显的新生内膜增生，新生内膜中抗增殖细胞核抗原（PCNA）阳性细胞率呈一峰值；2－4周期间，与对照侧比较，照射侧血管段新生内膜增生明显减弱（P＜0．01），新生内膜中PCNA阳性细胞率较对照侧低，差异有显著性意义（P＜0．01）；8－12周，照射侧血管段增生的新生内膜较对照侧仍处较低水平，新生内膜中PCNA阳性细胞率约低于1％。经抗平滑肌细胞α胶原免疫组织化学染色，证实新生内膜中主要为平滑肌细胞。结论 由照射所致的新生内膜增生过程的抑制作用从开始时即已启动。12Gy的^192Ir高线量率照射能有效地抑制用切割球囊导管损伤引起的日本白兔髂动脉新生内膜的过渡增生。     

PTA后再狭窄的血管内放射治疗研究现状

血管内放射治疗是抑制经皮血管腔内球囊扩张血管成形术(PTA)后再狭窄的一种新方法,在动物实验和临床研究中均取得明显效果。本文对血管内放射治疗抑制再狭窄的机制、放射源的选择、照射时间的选择和照射范围的界定、照射剂量的选择、放射源的传送方法和中心定位及其临床疗效和并发症作一综述。     

Endovascular brachytherapy for the prevention of restenosis after angioplasty

Restenosis is an unsolved clinical and financial limitation of angioplasty. Local irradiation is a new approach for the reduction of restenosis. Several animal studies have demonstrated the effective inhibition of arterial neointimal proliferation by percutaneous or endovascular irradiation. High-dose-rate irradiation from gamma and beta sources can be applied from radioactive wires or seeds and from liquid beta-emitter-filled balloon catheters. Dosimetric calculations have been performed for all relevant radionuclides. An effective dose can be applied within 10 min to the treated arteries. Beta-emitters are characterized by a low tissue penetration, which simplifies radiation protection but complicates the achievement of a homogeneous dose distribution without centering of the irradiation source. Gamma-emitters are characterized by deep tissue penetration and delivery of almost the same dose to all vessel layers; however, considerable care with regard to radiation protection of the environment is required if gamma-emitters are used. The liquid-filled balloon ensures a homogeneous dose delivery due to the self-centring irradiation source but entails the possibility of radioactivity incorporation in the event of balloon rupture. The most attractive radionuclide for this purpose is rhenium-188, which is available from the 188W/188Re generator system. Radiation exposure after accidental incorporation can be limited by chelation with mercaptoacetyltriglycine or by subsequent oral administration of perchlorate. Initial clinical trials have demonstrated the feasibility of the various irradiation techniques and yielded encouraging results. The use of unsealed radioactivity in a balloon catheter involves the nuclear medicine physician in this new field of therapy. This review discusses the concepts, the radiotracers and the results of animal experiments and early clinical trials in the field of endovascular irradiation employed as a possible means to prevent restenosis after angioplasty.     

Endovascular brachytherapy for the prevention of restenosis after angioplasty

Restenosis is an unsolved clinical and financial limitation of angioplasty. Local irradiation is a new approach for the reduction of restenosis. Several animal studies have demonstrated the effective inhibition of arterial neointimal proliferation by percutaneous or endovascular irradiation. High-dose-rate irradiation from gamma and beta sources can be applied from radioactive wires or seeds and from liquid beta-emitter-filled balloon catheters. Dosimetric calculations have been performed for all relevant radionuclides. An effective dose can be applied within 10 min to the treated arteries. Beta-emitters are characterized by a low tissue penetration, which simplifies radiation protection but complicates the achievement of a homogeneous dose distribution without centring of the irradiation source. Gamma-emitters are characterized by deep tissue penetration and delivery of almost the same dose to all vessel layers; however, considerable care with regard to radiation protection of the environment is required if gamma-emitters are used. The liquid-filled balloon ensures a homogeneous dose delivery due to the self-centring irradiation source but entails the possibility of radioactivity incorporation in the event of balloon rupture. The most attractive radionuclide for this purpose is rhenium-188, which is available from the ¹⁸⁸W/¹⁸⁸Re generator system. Radiation exposure after accidental incorporation can be limited by chelation with mercaptoacetyltriglycine or by subsequent oral administration of perchlorate. Initial clinical trials have demonstrated the feasibility of the various irradiation techniques and yielded encouraging results. The use of unsealed radioactivity in a balloon catheter involves the nuclear medicine physician in this new field of therapy. This review discusses the concepts, the radiotracers and the results of animal experiments and early clinical trials in the field of endovascular irradiation employed as a possible means to prevent restenosis after angioplasty.     

Therapeutic enema for pediatric ileocolic intussusception: using a balloon catheter improves efficacy

A therapeutic enema for pediatric intussusception may benefit by using a rectal catheter with an inflated balloon. We compared the efficacy of rectal catheters without and with an inflated balloon for air and liquid enemas. We retrospectively reviewed PACS images and hospital records of children who had a therapeutic enema for intussusception at our institution between January 2006 and May 2011. Sixty-two enemas in 60 children were included. Physician assistants with training in pediatric fluoroscopy and pediatric radiologists were more likely to use air enema (37/41 or 90 %), and general radiologists were more likely to use liquid enema (18/21 or 86 %). However, the reduction rate for air enema overall was only slightly higher than for liquid enema using an inflated balloon catheter (36/40 or 90 % versus 14/17 or 82 %) (P?=?0.653). For air enema, mean procedure time for successful reductions was shorter with an inflated balloon catheter than with a plastic catheter (7.6 versus 28.2 min) (P?<?0.009), but the reduction rate was not affected. For liquid enema, the reduction rate was higher with an inflated balloon catheter than without inflation (14/17 or 82 % versus 1/5 or 20 %; P?=?0.021), but the procedure time was not shortened. No procedural complications were directly attributed to using a rectal catheter with an inflated balloon. Using a rectal catheter with an inflated balloon appears to safely shorten the procedure time of a successful air enema and improve the reduction rate of liquid enema.     

32P液体球囊血管内照射预防血管成形术后再狭窄

目的 探讨^32P液体球囊血管内近距离照射治疗对防止血管成形术后再狭窄的量效关系及其抑制再狭窄发生的可能机制。方法 27只雌性大白兔据动脉球囊扩张损伤后，实验组(18只)分别给予3、9、18和36Gy^32P液体球囊行内照射治疗，对照组(9只)灌注生理盐水。术后于不同时间点取材，行HE染色、增殖细胞核抗原(PCNA)免疫组织化学染色以及电镜观察血管组织形态学的改变，用计算机图像分析法测量管腔面积和内膜面积。结果 对照组血管内膜明显增生，管腔变狭窄。18Gy组血管壁平滑肌细胞增殖明显受抑，细胞凋亡增加，管腔面积无明显丢失；36GY组血栓形成明显；3和9Gy组均未观察到明显的生物效应。结论 ^32P液体球囊血管内照射可防止血管成形术后再狭窄发生，其机制可能为抑制血管壁平滑肌细胞增殖，促进其凋亡及改善血管重塑形。     

Monte Carlo dose simulation for intracoronary radiation therapy with a rhenium 188 solution-filled balloon with contrast medium

BACKGROUND: The therapeutic efficacy of percutaneous transluminal coronary angioplasty is limited by the incidence of restenosis. Intracoronary irradiation has shown to be effective in restenosis control by inhibiting the neointimal proliferation. METHODS AND RESULTS: Monte Carlo simulation has been performed to calculate the dose to the vessel wall for intracoronary irradiation with a rhenium 188 solution-filled balloon for restenosis inhibition. With a 3-mm-diameter and 30-mm-long balloon, the radiation dose at 1 mm from the balloon surface was 5.3% lower when the balloon structure was included in geometric modeling of the angioplasty catheter, as compared with that obtained by ignoring the structure. The additional dose reduction due to Hexabrix 320 contrast medium added in 30% of volume ratio was 4.7%. With regard to axial dose distribution, the dose was uniform over the balloon length except near the balloon end, at which the dose was reduced by 35% at a 1-mm-deep layer in the vessel wall. With the Re-188 solution mixed with 30% of Hexabrix 320 in volume ratio, the Re-188 activity to be injected for delivery of 15 Gy to the 1-mm-deep layer by 1-minute irradiation was 27.3 GBq/mL. CONCLUSIONS: Dose estimates produced in this study should be helpful in determining the Re-188 activity to be injected or the irradiation time for a varying situation in terms of length and diameter of the irradiated arterial segment and depth of the target layer.     

Potential (166)Ho radiopharmaceuticals for intravascular radiation therapy (IVRT)-I: [(166)Ho] holmium labeled ethylene dicysteine

The use of beta(-) emitting radionuclides in the control of restenosis in post angioplasty patients is currently under intense investigation at many leading cardiovascular research centers. (32)P coated metallic stents, (192)Ir wire source and balloons filled with an appropriate radionuclide solution such as of (188)Re, attached to catheter are being studied. (166)Ho has comparable radionuclidic properties to that of (188)Re, can be more easily produced and hence is an attractive alternative to (188)Re. Ethylene dicysteine complex of (166)Ho was prepared and its pharmacological behavior studied. Optimum conditions for the preparation of complex with respect to the reaction time, ligand concentration, pH of the reaction mixture as well as reaction temperature were standardized. The stability of the labeled complex at room temperature as well as at 4 degrees C was determined. Biodistribution pattern of the injected complex in Wistar rats was estimated at 10 min, 30 min and 3 h post injection. This study indicated that >90% of the injected (166)Ho-EC complex was excreted in urine within 3 h post injection, with insignificant retention in any major organ. These studies reveal that (166)Ho-EC could be a viable substitute for (188)Re compounds in radioactive liquid-filled balloon IVRT.     

Development of a New Coaxial Balloon Catheter System for Balloon-Occluded Retrograde Transvenous Obliteration (B-RTO)

Purpose To develop a new coaxial balloon catheter system and evaluate its clinical feasibility for balloon-occluded retrograde transvenous obliteration (B-RTO). Methods A coaxial balloon catheter system was constructed with 9 Fr guiding balloon catheter and 5 Fr balloon catheter. A 5 Fr catheter has a high flexibility and can be coaxially inserted into the guiding catheter in advance. The catheter balloons are made of natural rubber and can be inflated to 2 cm (guiding) and 1 cm (5 Fr) maximum diameter. Between July 2003 and April 2005, 8 consecutive patients (6 men, 2 women; age range 33–72 years, mean age 55.5 years) underwent B-RTO using the balloon catheter system. Five percent ethanolamine oleate iopamidol (EOI) was used as sclerosing agent. The procedures, including maneuverability of the catheter, amount of injected sclerosing agent, necessity for coil embolization of collateral draining veins, and initial clinical results, were evaluated retrospectively. The occlusion rate was assessed by postcontrast CT within 2 weeks after B-RTO. Results The balloon catheter could be advanced into the proximal potion of the gastrorenal shunt beyond the collateral draining vein in all cases. The amount of injected EOI ranged from 3 to 34 ml. Coil embolization of the collateral draining vein was required in 2 cases. Complete obliteration of gastric varices on initial follow-up CT was obtained in 7 cases. The remaining case required re-treatment that resulted in complete obstruction of the varices after the second B-RTO. No procedure-related complications were observed. Conclusion B-RTO using the new coaxial balloon catheter is feasible. Gastric varices can be treated more simply by using this catheter system.