测量方法对^125I密封籽源活度值的影响研究

目的 研究各种因素（包括测量的几何位置、不同容器、自屏蔽、容器壁厚等）对^125I密封籽源表观活度测量的影响，建立理想的测量条件。方法将^125I密封籽源直立在1ml尖底放免管中，放入CRC-15R活度计的小托盘中进行测量。结果 不同测量条件对^125I密封籽源表观活度测量有影响。结论 在最佳测量条件下，测量的^125I密封籽源表观活度比较准确。     

测量125I放射性活度的相加峰符合法

本文介绍测量¹²⁵I放射性活度的相加峰符合法。通过测量¹²⁵I衰变放射的27.5kevx射线飘135.5keVγ 射线单一峰计数率及这两种射线相加峰计数率,可准确的计算出¹²⁵I源的放射性活泼。本法与测量¹²⁵I活度的相对法比较,具有使用方便,不需要对计算系统进行刻度,以及测量结果几乎不受样品源体积、源在探测器中的位置和样品源容器类型的影响等优点,是核医学和辐射防护中测量¹²⁵I放射性活度的较为理想的一种方法。     

125Ⅰ密封籽源用于肿瘤治疗的动物实验初步研究

目的研究125I密封籽源对Hela细胞的杀伤作用以及对肿瘤的抑制作用.方法通过内植入法将125I密封籽源植入荷瘤鼠的肿瘤内,观察其对肿瘤的抑制作用以及血液学毒性.结果125I密封籽源对Hela细胞杀伤明显,照射48h的杀伤范围为1.6～2.4mm,对肿瘤有明显的抑制作用,对血象和生化指标无明显影响.结论125I密封籽源组织植入治疗法能有效抑制肿瘤的生长,并达到了治疗的效果.     

^125I密封籽源用于肿瘤治疗的动物实验初步研究

目的：研究^125I密封籽源对Hela细胞的杀伤作用以及对肿瘤的抑制作用。方法：通过内植入法将^125I密封籽源植入荷瘤鼠的肿瘤内，观察其对肿瘤的抑制作用以及血液学毒性。结果：^125I密封籽源对Hela细胞杀伤明显，照射48h的杀伤范围为1．6～2．4mm，对肿瘤有明显的抑制作用，对血象和生化指标无明显影响。结论：^125I密封籽源组织植入治疗法能有效抑制肿瘤的生长．并达到了治疗的效果。     

用热释光剂量学法和理论计算法研究125Ⅰ粒籽源的剂量分布

目的研究实验模型中~(125)I粒籽的剂量分布。方法采用热释光剂量学方法(TLD法)和美国医学物理学家协会43报告工作组(AAPM TG-43)推荐的理论计算公式(理论计算法)对~(125)I粒籽的径向剂量进行了研究,并对TLD法和理论计算结果进行比较。结果当~(125)I粒籽活度为37 MBq,粒籽的径向距离分别为0．5、1．0、1．5和2 cm时,用TLD法测得的径向剂量率分别为3．47、0．87、0．38、0．21 cGy/h,理论计算法分别为3．874、0．952、0．394、0．216 cGy/h。结论TLD法和理论计算法有较好的一致性,~(125)I粒籽源的径向剂量率随距离增加快速下降。     

125I粒子不同分布组织间植入对荷人胃癌裸鼠移植瘤疗效的影响

目的 探讨125I粒子总活度相同时,不同分布的组织间植入对荷人胃癌裸鼠移植瘤疗效的影响.方法 建立人胃低分化腺癌BGC-823细胞裸鼠皮下移植瘤模型32只,按随机数字表法分为实验组和对照组.实验组植入总活度33.30 MBq125I粒子,按照植入单枚活度及分布不同分为高活度组(33.30 MBq×1枚)、中活度组(16.65 MBq×2枚)、低活度组(11.10 MBq×3枚);对照组植入空源粒子.每组8只裸鼠模型.比较实验和对照组及125I粒子不同分布状态下对移植瘤体积的抑制率、组织病理学改变、局部皮肤反应、裸鼠体质量和存活率.采用方差分析和秩和检验对数据进行统计学处理.结果 各组存活率均为100%.125I粒子植入第30天裸鼠体质量各组比较,差异无统计学意义[高、中、低活度及对照组分别为(26.44±1.07)、(26.58±0.51)、(27.15±1.37)和(26.92±0.60)g,F=2.23,P>0.05].第30天各实验组125I粒子对肿瘤体积抑制率分别为92.47%,97.15%和89.01%;平均体积各实验组[高、中、低活度组分别为(138.85±16.45)、(52.52±30.54)、(202.72±126.97)mm3]与对照组[(1843.99±447.63)mm3]比较,差异均有统计学意义(t值分别为3.092,3.376,3.269,P均<0.05),中活度组和低活度组组间比较差异有统计学意义(t=2.308,P<0.05),高活度组分别和中活度组、低活度组组间比较差异均无统计学意义(t值分别为1.300,1.007,P均>0.05).高活度组与中活度组组织病理学分级按直肠癌消退分级标准(RCRG)均为RCRG 1级;低活度组3只为RCRG 3级,4只为RCRG 2级,1只为RCRG 1级.中、低活度组均未出现放射性损伤,高活度组中4只裸鼠于125I粒子植入后9～12 d出现放射治疗肿瘤学组织(RTOG)1～2级放射性损伤.结论 125I粒子植入治疗中单源活度的选择和分布方式可直接影响疗效和放射性损伤的程度.     

不同活度125I粒子植入抑制兔VX2肝癌机制研究

目的：探讨125I粒子组织间植入诱导肝癌细胞凋亡的机制。比较不同活度125I粒子组织间植入诱导肿瘤细胞凋亡、抑制肿瘤细胞增殖的作用强度。方法将24只兔VX2肝癌模型随机分为3组,分别植入不同初始活度的125I粒子：0 mCi组（对照组,n=8）、0.7 mCi组（n=8）及1.0 mCi组（n=8）。5周后处死实验兔,取出肿瘤病灶,检测125I粒子对肿瘤细胞凋亡、肿瘤生长相关因子表达的影响及caspase-3活性改变。结果不同初始活度125I粒子均可使肿瘤细胞凋亡率上升, Bcl-2、VEGF表达下调,Bax表达上调,1.0 mCi 125I粒子组作用均更加明显（P＜0.05）。不同初始活度125I粒子可增加肿瘤组织中caspase-3活性,两治疗组间差异无明显统计学意义（P＞0.05）。结论125I粒子植入后不仅通过诱导肿瘤细胞凋亡抑制肿瘤生长、增殖,还影响凋亡相关基因及编码蛋白表达,抑制肿瘤细胞新生血管生成。     

125I籽源连续照射诱导人乳腺癌细胞凋亡的研究

目的探讨125I籽源低剂量率γ射线持续照射诱导MCF-7人乳腺癌细胞凋亡过程中Bcl-2/Bax的变化情况.方法用9粒表面放射活度为27.75 MBq的6711型125I籽源连续照射MCF-7细胞72 h后,采用RT-PCR和Western blot法检测Bcl-2和Bax mRNA和蛋白表达.常规细胞流式法和Annexin V标记法直接检测MCF-7细胞凋亡率.结果 MCF-7细胞经125I籽源照射后较对照组Bcl-2 mRNA的表达降低,Bax mRNA的表达升高;Western blot检测Bcl-2/Bax比值,结果对照组为1.89±0.09,125I籽源照射组为0.62±0.08,两者差异有统计学意义(P＜0.05).常规细胞流式法检测照射组(n=10)和对照组(n=12)细胞凋亡率分别为(23.61±7.27)%和(2.81±1.68)%,P＜0.05.Annexin V标记法检测两组细胞早期凋亡率分别为(21.46±8.29)%和(1.94±1.38)%,P＜0.05.结论 125I籽源连续照射能够诱导Bcl-2/Bax比值的降低,促进MCF-7细胞的凋亡.     

125I植入对小鼠移植性实体瘤抑制效果

目的观察12I籽源组织间植入对小鼠移植性实体瘤的治疗效果.方法建立小鼠艾氏腹水瘤细胞移植性实体肿瘤模型.治疗组在肿瘤组织内平均植入4粒表面放射活性为8.14MBq的BT-125-Ⅰ型125I籽源,对照组植入4粒无放射活性的空心籽源.治疗28 d,记录小鼠存活率.处死存活的小鼠,测量残存肿瘤的体积、重量并计算肿瘤体积抑制率.对摘除的肿瘤组织进行常规病理切片检查,观察籽源对肿瘤组织的破坏程度和范围.结果治疗28 d,治疗组和对照组小鼠存活率分别为75%和50%;平均瘤重分别为(0.347±0.25)g,(5.162±1.75)g(t=6.164,P＜0.05);肿瘤平均体积分别为(175.9±147.9)mm3,(3974.1±1507.7)mm3(t=5.618,P＜0.05),肿瘤体积抑制率为95.6%.常规病理切片结果显示,125I籽源周围0～3 mm范围内肿瘤细胞病理变化由凝固坏死向外逐渐减弱为变性坏死;空心籽源周边区域仅有机械刺激导致的轻微水肿和纤维化.结论125I籽源组织间植入对小鼠实体肿瘤具有显著的治疗效果.     

放射性125I粒籽源的剂量分布

采用放射性^125I粒籽源永久性植入治疗恶性肿瘤，使肿瘤部位受照剂量高，有助于肿瘤的整体杀灭，而对周围正常组织造成损伤较小，在我国已有研究报道。本研究采用热释光剂量学方法，研究放射性^125I粒籽源治疗恶性肿瘤的剂量及剂量分布，为临床近距离治疗提供科学的剂量依据。现将单颗^125I粒籽源的剂量分布结果报道如下。     

CT引导下125I籽源植入近距离放射治疗多发性椎体转移癌

目的探讨~(125)I籽源植入近距离放射治疗多发性椎体转移患者的价值。方法15例癌症多发椎体转移患者(共43个椎体)进行了CT引导下~(125)I籽源植入近距离放射治疗。肺癌术后椎体转移7例,乳腺癌术后椎体转移4例,肝癌术后椎体转移2例,前列腺癌术后椎体转移1例,左肾癌术后椎体转移1例。共43个椎体转移,每例椎体转移数为2～5个。在CT引导下按共轴针法投放籽源,视病变情况采取椎弓根入路、侧方入路、前入路等3种方式将~(125)I籽源植入椎体病变区,籽源呈倒V形、X形或平行分布,籽源距椎体后缘3～10mm。~(125)I籽源总活度由公式(长 宽 高)(cm)/3×5mCi计算或"放射性粒子源植入治疗计划系统"计算获得,单椎体植入剂量8～22mCi。椎旁软组织病变内同时植入~(125)I籽源。结果术后随访3～30个月,平均12.3个月,15例患者术后均未出现脊髓、神经损伤等并发症,未出现放射相关不良反应。11个没有疼痛的部位未出现新的疼痛,18/32部位症状体征消失,14/32部位部分消失。最短术后第3天觉得症状已有缓解。影像表现,10例患者29个椎体影像回访,治疗3个月以后7例17个椎体CT可见病灶稳定,边缘形成硬化环。4个椎体病变进展,见硬化环不完整,破坏区有扩大。3例8个椎体MRI显示骨水肿明显减轻,病变区T_2WI信号减低。结论~(125)I籽源植入近距离放射治疗多发性椎体转移癌具有疗效高,创伤小,并发症发生率低等优点,是一种较好的微创治疗方法,不仅适合于未经治疗的患者,也适合于放射治疗后复发的患者,具有较高的耐受性和安全性。     

Dosimetric consideration of individual 125I source strength measurement and a large-scale comparison of that measured with a nominal value in permanent prostate implant brachytherapy

Purpose We investigated the difference between measured and manufacturer's nominal source strength in a large sample of a single model of ¹²⁵I seeds. Physical characteristics of single seed measurement by the well-type ionization chamber were also investigated to provide dosimetric data. Materials and methods A well-type ionization chamber with a single seed holder was used to measure source strength of all 1935 ¹²⁵I seeds implanted in the initial 28 patients in our hospital. Physical characteristics including linearity of readings for different integral time intervals, reproducibility, isotropy, and axial positional sensitivity were assessed. To calculate the source strength, the integral charge during 30 s was measured and converted to air kerma strength. The nominal activity stated by the manufacturer was compared with the measured value. Results Linearity, reproducibility, and isotropy of the well-type ionization chamber were within 0.2%. Measured source strength was on average 2.1% (range −7.6% to +7.2%), lower than the nominal value. Standard deviation of all measured seeds was 2.0%. The maximum difference between the measured and the manufacturer's nominal source strength in each patient was −3.7%. The standard deviation averaged 1.6%. Conclusion The nominal source strength of the ¹²⁵I seeds agreed well with the measured value. Our study can be helpful as guidance for individual ¹²⁵I seed source strength measurement.     

纤维支气管镜下植入~(125)I粒子治疗中央型肺癌

目的 评估植入~(125)I粒子治疗中央型肺癌的临床价值.方法 56例确诊的晚期中央型肺癌患者,经纤维支气管镜引导植入125I粒子,定期复查,观察疗效及不良反应.结果 56例中央型肺癌患者经治疗总有效率达76.78%,肺不张复张有效率为90.90%.结论 ~(125)I粒子经纤维支气管镜植入治疗晚期中央型肺癌有效,且安全可行.     

CT引导125Ⅰ粒子植入治疗非小细胞肺癌的剂量学验证

目的对125Ⅰ粒子植入治疗非小细胞肺癌进行剂量学验证.方法37例确诊的非小细胞肺癌患者,由放射治疗计划系统(TPS)通过CT引导植入125Ⅰ粒子,并行验证.定期进行复查.结果除2例无效外,1O例患者的病灶消失,25例明显缩小;瘤体的平均吸收剂量为150.5 Gy,匹配周缘吸收剂量(DMP)为86.6 Gy,靶区90%体积的吸收剂量(D90)为92.4 Gy,D90＞DMP.结论125Ⅰ粒子植入治疗非小细胞肺癌安全可行.     

~(125)I粒子治疗对肝癌细胞凋亡及细胞周期的影响

~(125)I粒子低剂量率连续照射肝癌细胞,能明显上调细胞Bax表达,降低Bcl-2表达,同时明显诱导细胞凋亡的发生,且细胞周期发生再分布,照射后细胞被阻滞在对辐射相对敏感的G_2-M和S期.研究结果表明,~(125)I粒子连续照射能够通过诱导凋亡的途径,明显杀伤肿瘤细胞.     

125I放射粒子在肿瘤介入治疗中的应用

目的 探索采用介入微刨技术进行放射粒子病灶内植入的可行性、安全性及疗效;比较不同影像设备在粒子植入术中的作用及优缺点。方法 入选30例患者,其中15例为晚期肿瘤转移患者,15例为失去手术机会的食管癌患者。粒子植入方法：在B超或CT定位下行经皮穿刺病灶内粒子植入术;在DSA监视下将捆绑有放射粒子的食管支架植入到食管病变部位。结果 在B超、CT及DSA监视下,除因操作原因造成食管内照射支架上丢失一颗放射粒子外,所有放射粒子均准确植入到位。术后随访,患者临床症状均有明显改善;未发现局部皮肤坏死、出血、感染、放射性肺炎、食管穿孔等与粒子照射相关的并发症;手术前后连续血象、免疫指标复查未发现显著性变化。ECT复查：放射源未发现泄漏。病灶复查：15例食管癌患者1个月后胸部CT复查示13例病变厚度和体积较术前有所缩小,2例病变增大,3例随访近13个月,CT复查病变厚度较术前明显变薄;5例直接置入无膜内照射支架患者中3例术后3个月胃镜复查并活检提示支架捆绑粒子部位肿瘤明显退缩,未发现肿瘤细胞生长。15例经皮穿刺植入粒子的患者在术后2个月病变明显缩小。结论 采用介入微创技术进行放射粒子病灶内植入是可行的、安全的,疗效是明确的。     

A Monte Carlo evaluation of the dosimetric characteristics of the EchoSeed Model 6733 (125)I brachytherapy source

PURPOSE: Recently a new design of a (125)I brachytherapy source was introduced for interstitial seed implants, particularly for prostate seed implants. This new source is the EchoSeed Model 6733 (125)I brachytherapy source. Due to the differences in source design and manufacturing process from one new source to the next, their dosimetric parameters should be determined according to the American Association of Physicists in Medicine (AAPM) TG-43 guidelines. METHODS AND MATERIALS: As per AAPM recommendation, it is required to perform at least one experimental study and one Monte Carlo simulation, preferably done by two independent investigators. Other investigators have experimentally determined the dosimetric parameters of this new source. In this project, the Monte Carlo simulated dosimetric parameters of the EchoSeed Model 6733 source have been provided. RESULTS: The results of this evaluation indicate the value of the dose rate constant of 0.97 +/- 3% cGyh(-1)U(-1) in liquid water, which is in good agreement with the measured value of 0.99 +/- 8% cGyh(-1)U(-1) reported by Meigooni et al. The anisotropy constant of the EchoSeed (125)I brachytherapy source was found to be 0.960 in liquid water. CONCLUSIONS: The Monte Carlo Simulated TG-43 dosimetric parameters of the EchoSeed were determined and the results were compared with the published measured data.     

Studies on the production and quality assurance of miniature (125)I radioactive sources suitable for treatment of ocular and prostate cancers.

(125)I sources were prepared by adsorption of (125)I on palladium-coated silver wires. The effect of reducing agent on percentage adsorption of (125)I was studied and the amount of adsorbed activity on source core was studied by repeated adsorption cycles. The activity per source in the sources produced from the same batch varied with coefficient of variation (i.e. the ratio of standard deviation to mean multiplied by 100) less than 10%. The unencapsulated source exhibited low leachability (< 0.01%). The laser parameters were optimized to obtain quality welds with negligible leak rate. The sources were laser-encapsulated in titanium capsules of 0.8 mm (OD) x 4.5mm (l). The release of radioactivity from encapsulated sources in an immersion test at 50 degrees C for 5 h was <5 nCi (185 Bq). The surface contamination on the sealed capsules was found to be<0.05 nCi or 1.85 Bq per source. The sources were used in the treatment of a child having retinoblastoma.     

兔门静脉主干内植入连续排列~（125）I粒子条的实验研究

目的 评价兔门静脉腔内植入连续排列125I粒子条的安全性.方法 将20只新西兰大白兔随机分成两组并编号,包括实验组(T组)和对照组(C组).实验组动物将封装在导管内连续排列的3粒125I粒子条经开腹、穿刺,悬挂固定在门静脉主干内壁.对照组仅开腹门静脉作荷包缝合.术后14、28、60和120 d分别抽血标本并行CT检查和直接门静脉造影.实验组、对照组在14、28和60 d造影后分别处死2只动物;120 d时处死剩余动物.收取门静脉主干,邻近肝、肠等组织及远处肝组织行病理检查.结果 实验组动物未发现125I粒子辐射相关的呕吐、腹泻、体重下降等症状及死亡.MDCT及DSA均显示门静脉血流通畅.病理大体标本未显示门静脉穿孔,狭窄及血栓形成,植入粒子条与管壁无粘连.实验组镜下见血管内皮细胞坏死、脱落,中膜及外膜无改变.临近125I粒子旁肝细胞坏死明显,肝右叶下角及十二指肠组织无异常.两组间血常规及肝功能比较差异无统计学意义(P>0.05).结论 连续排列125I粒子条兔门静脉管腔内植入安全、可行.     

A Monte Carlo evaluation of the dosimetric characteristics of the Best Model 2301 125I brachytherapy source.

Recently a new design of a 125I brachytherapy source was introduced for interstitial seed implants, particularly for prostate seed implants. This new source is the Best Model 2301 brachytherapy source. Due to the differences in source design and manufacturing process from one new source to the next, their dosimetric parameters should be determined according to the AAPM TG-43 guidelines. As per AAPM recommendation (Med. Phys. 25 (12) (1998) 2269), it is required to perform the seed dosimetry using at least one experimental study and one Monte Carlo simulation, preferably done by two separate investigators. Other investigators have experimentally determined the dosimetric parameters of this new source. In this project, the Monte Carlo simulated dosimetric parameters of the Best Model 2301 125I source have been provided. The results of this evaluation indicate the value of dose rate constant of 1.01 +/- 3% cGyh-1U-1 in liquid water, which is in good agreement with 1.02 +/- 8% cGyh-1U-1 reported by Nath and Yue, 2002. The anisotropy constant was found to be 0.98 in liquid water.