90Y树脂微球治疗在临床应用中的放射防护研究

目的 探讨⁹⁰Y树脂微球治疗在临床应用中的放射防护措施。方法 模拟⁹⁰Y树脂微球治疗手术流程,通过监测术前药物分装准备、药物转运、术中药物操作和输注、术后患者住院观察各个阶段周围剂量当量率水平,分析临床应用中所应采取的放射防护措施。结果 活性室周围剂量当量率水平为0.12~0.42 μSv/h,通风橱周围剂量当量率为1.04~3.32 μSv/h。数字减影血管造影(DSA)室在⁹⁰Y+DSA扫描时最高为0.78 μSv/h,在⁹⁹Tc^m+DSA时最高为 0.36 μSv/h; 透视防护区在⁹⁰Y药物时在第一术者位155 cm高度为13.19 μSv/h,而在⁹⁰Y+DSA扫 描时最高为80 cm高度处315.01 μSv/h。第二术者位在⁹⁰Y药物时最高为155 cm高度为6.28 μSv/h, ⁹⁰Y+DSA 扫描时最高为155 cm高度处291.03 μSv/h。患者病房周围剂量当量率为0.11~0.58 μSv/h。 结论 核医学科及介入室等原有屏蔽措施能够满足⁹⁰Y树脂微球治疗的放射防护要求,但仍需根据实际情况进行科学评估,同时应加强药物操作中的放射防护及表面污染处理措施。     

核医学诊断工作场所辐射水平及防护现状调查

目的 对我国核医学诊断工作场所辐射防护现状进行调查.方法 2013年2—12月期间,在东北、华中和华北地区分别选择1家三甲医院,用γ剂量率仪巡测核医学诊断制药、淋洗、分装、注射、扫描过程中工作场所周围剂量当量率,光致发光剂量计测量放射工作人员个人有效剂量和当量剂量.结果 在放射性药物分装、注射和受检者摆位等操作环节中周围剂量当量率较高, 分装时最高达1.92 mSv/h,注射时距针管5 cm处剂量率最高达1.2 mSv/h,受检者体表30 cm处剂量率范围为5.36~240 μSv/h,某医院护士手部当量剂量为0.01~0.02 mGy,部分工作场所存在人员路线交叉及注射后受检者停留在公众区域的现象.结论 核医学实践中放射工作人员应加强个人防护,提高操作熟练程度以缩短作业时间,应优化放射工作人员出入路线,加强注射后受检者的管理,以免公众人员受到不必要的照射.     

18F-FDG PET显像中受检者周围人员的辐射剂量监测

目的　为1 8F 脱氧葡萄糖 (FDG)PET显像过程中工作和陪护人员的临床辐射防护提供参考数据。方法　用辐射剂量仪分别测量 30例工作人员在注射室、显像室的剂量当量率及受检者注射1 8F FDG后即刻、1和 2h距前胸 0 1、0 5、1 0、2 0m的剂量当量率 ,计算每例检查每一步操作的剂量当量和各工作场所工作人员的年剂量当量。结果　工作人员每例各步操作平均个人剂量当量为药品分装 :左手 (30 0± 8 0 ) μSv,右手 (6 0± 1 5 ) μSv ,全身 (0 5± 0 1) μSv;注射 :手部 (3 0 0± 0 75 )μSv,全身 (1 2 7± 0 2 0 ) μSv ;摆位和采集 ,结束采集共 (9 9± 1 4 ) μSv;密切接触的陪护人员为 (310±91) μSv。各工作场所工作人员的累计年剂量当量分别为 :药品分装及注射 :左手 (16 6 3± 4 4 1)mSv,右手 (6 4 5± 1 2 3)mSv ,全身 (1 18± 0 15 )mSv;显像采集 :全身 (4 99± 0 70 )mSv。结论　通过现有防护设施和方法 ,工作人员和陪护人员的受照剂量均未超过国家辐射安全标准 (GBSS)关于职业及公众个人年剂量限值。     

RDS111型回旋加速器辐射剂量监测与防护

目的监测回旋加速器运行过程中产生的辐射水平及其与靶电流之间的关系,为相关人员的防护提供参考.方法用剂量仪分别测量美国CTI RDS111型回旋加速器在靶电流为40μA时生产11C、13N、15O、18F 4种核素在大厅内外的γ和中子剂量率及不同靶电流下的剂量当量率,并计算相关人员可能的年剂量当量.结果回旋加速器大厅内除1个点外,其余各处剂量当量率均小于15 μSv/h,大厅外周围环境则均小于0.5 μSv/h.相关人员可能的年剂量当量小于1.04mSv.线性拟合示,剂量当量率与束流强度呈正比.结论正常情况下,相关人员吸收剂量均未超过国家安全标准中关于职业人员（20 mSv）和公众个人（5 mSv）的年剂量当量限值.     

江苏省2011-2018年放射工作人员职业性外照射个人剂量监测结果分析

目的了解江苏省2011—2018年放射工作人员个人剂量监测基本情况,分析其变化趋势,为保护放射工作人员健康管理提供理论基础和科学依据。方法通过国家个人剂量登记系统,采集我省放射工作人员职业外照射个人剂量监测结果等相关数据,对其进行回顾分析。结果2011—2018年监测江苏省放射工作人员共176134人,总年集体有效剂量58人·Sv,期间人均年有效剂量为0.35 mSv。医用放射工作人员中从事介入放射学、核医学人均年有效剂量均为0.41 mSv,其高剂量人员构成比显著高于其他职业类别(χ²=219.1,P<0.05)。至2018年医疗放射工作人员为25714人,占81%,年平均有效剂量为0.24 mSv;工业放射工作人员为6169人,占19%,年平均有效剂量为0.18 mSv。结论江苏省放射工作人员人均年有效剂量符合国家标准要求,介入和核医学的放射工作人员人均年有效剂量相对较高,应改进和完善工作场所防护措施,同时应加强工业放射工作人员管理监督。     

湖北省2009-2018年放射工作人员职业性外照射剂量监测结果分析

目的回顾性分析湖北省2009—2018年间放射工作人员职业性外照射个人剂量水平与分布情况,预防和控制放射性职业照射的风险。方法以2009—2018年委托湖北省疾病预防控制中心进行个人剂量监测的放射工作人员外照射个人剂量为研究对象,共50070人。按照相关国家标准的要求,采用热释光方法监测放射工作人员的外照射剂量当量。结果10年间放射工作人员平均年集体有效剂量为1.93人·Sv,人均年有效剂量中位数为0.14 mSv(P25~P75为0.06~0.30 mSv),人均年有效剂量为0.40 mSv;年有效剂量<1 mSv的有46562人,占总监测人群的92.99%。不同职业类别的年有效剂量变化趋势不尽相同,但总体趋势均呈逐年下降的态势,并于2012年之后维持在较低水平。医学应用中核医学和介入放射学、工业应用中探伤和测井以及其他类放射工作人员人均年有效剂量相对较高。结论人均年有效剂量呈逐年降低并维持较低水平的趋势,表明10年间的放射防护措施基本能够保障其健康权益。连续性的监测结果提示,需对职业类别如核医学、介入放射学、探伤和测井以及其他类应用的放射工作人员予以重点关注,保障放射防护措施。     

68Ga-奥曲肽PET/CT显像患者对周围人群产生的有效剂量的估算

目的 估算68Ga-奥曲肽PET/CT显像患者对周围人群产生的有效剂量。 方法 采用简单随机抽样的方法选取2021年10至12月于北京大学肿瘤医院接受68Ga-奥曲肽PET/CT显像的20例患者进行前瞻性研究,其中男性15例、女性5例,年龄30~68（49.0±12.2）岁。在患者静脉注射68Ga-奥曲肽0 h后,使用辐射监测剂量仪测量距患者1.0 m处的空气吸收剂量率,注射1.0 h后测量距患者0.3 m处的空气吸收剂量率,注射1.5 h后测量距患者0.3、0.5、1.0和1.5 m处的空气吸收剂量率。依据美国国家辐射防护和测量委员会第155号报告提出的人类社会活动模式,采用积分法估算68Ga-奥曲肽PET/CT显像患者对周围人群产生的有效剂量。 结果 注射68Ga-奥曲肽0 h后,距患者1.0 m处的空气吸收剂量率为12.97~33.67 （20.24±6.57） μSv/h;注射1.0 h后,距患者0.3 m处的空气吸收剂量率为32.73~57.69（48.98±6.20） μSv/h;注射1.5 h后,距患者0.3、0.5、1.0、1.5 m处的空气吸收剂量率分别为24.04~42.39（35.98±4.56） μSv/h、11.83~28.83（20.70±4.55） μSv/h、5.17~13.42（8.07±2.61） μSv/h、1.51~7.01（3.75±1.72） μSv/h。与68Ga-奥曲肽显像患者白天接触的家庭成员受照的有效剂量为8.22~21.33（12.83±4.15） μSv,夜间同床共睡的家庭成员受照的有效剂量为38.92~68.62（58.25±7.38） μSv,单位同事受照的有效剂量为8.37~21.73（13.06±4.23） μSv,同车邻座乘客受照的有效剂量为32.97~58.15（49.36±6.26） μSv。每接触一例患者,操作人员受照的有效剂量为2.66~4.69（3.98±0.50） μSv,陪护护士受照的有效剂量为9.70~25.17（15.13±4.90） μSv。 结论 68Ga-奥曲肽PET/CT显像患者对周围人群产生的有效剂量远低于国家标准规定的有效剂量限值。     

回旋加速器工作场所辐射水平的调查与分析

目的 调查回旋加速器工作场所辐射剂量水平及其分布状况, 以期更好地指导现场人员的防护并为放射性药物生产场所的屏蔽设计提供技术依据。 方法 以某医院安装的1台HM-20S型回旋加速器及其放射性药物生产场所为研究对象, 使用LiF(Mg, Cu, P)热释光剂量计、CR39中子剂量计、NH-1B中子剂量当量率仪和451B剂量巡测仪测量加速器室内中子和γ射线辐射剂量率, 并对室外关注点的辐射水平进行验证。 结果 在质子能量20 MeV、束流100 μA条件下, 回旋加速器自屏蔽体南侧表面中子最高剂量率为北侧表面的63倍、γ射线最高剂量率为北侧的6. 0倍; 机房南墙内表面中子和γ射线剂量率分别为北墙内表面的11倍和5. 3倍; 机房东墙内表面中子和γ射线剂量率平均值分别为21 μSv/h和45 μSv/h, 西墙内表面中子和γ射线剂量率平均值分别为34 μSv/h和69 μSv/h。 结论 回旋加速器室内辐射水平及其分布状况与束流方向和靶位置等因素密切相关, 其实测值可用于指导场所的屏蔽设计和人员防护。     

钇-90微球的特性、放射栓塞的操作技术及安全防护——钇-90微球放射栓塞系列回顾(一)

钇-90(90Y)微球放射栓塞是一种局部治疗方法,它将载有发射β射线的90Y树脂或玻璃微球选择性地注射到肝动脉.90Y微球随血流被阻塞在肿瘤血管床,其发出的射线对靶肿瘤具有细胞毒性作用.该方法的安全性和有效性已经在不可切除的肝脏恶性肿瘤患者中得到证实.本文作为90Y微球放射栓塞系列综述的第一部分,将讨论90Y和90Y微球的基本特性,90Y微球放射栓塞的基本操作方法,以及放射性安全与防护.     

新型头部γ刀建设项目放射防护控制效果评价

目的 评价新型头部γ刀机房的放射防护状态及防护设施的有效性、合理性,进而保证相关人员的健康安全。 方法 依据国家有关法规和标准,结合建设单位提交的新型γ刀及机房的材料,进行现场调查和放射防护检测,然后综合分析评价。 结果 新型头部γ刀性能检测结果满足GBZ 168-2005标准的要求;工作场所的周围剂量当量率在0.11~0.18 μSv/h,γ刀机房屏蔽满足放射防护要求;个人防护用品等放射防护设施和工作人员个人剂量监测、健康体检制度及相应的规章制度均达标。 结论 该新型头部γ刀建设项目可有效控制放射性职业病危害因素,放射防护设施达到了竣工验收的要求。     

人体中的镭-226、镭-228、钋-210、铅-210

本文报道了广东阳江高本底地区6名、对照地区8名人尸体的骨²²⁶Ra、²²⁶Ra的浓度以及部分居民内脏器官中。²¹⁰Po、²¹⁰Pb的浓度。结果轰明阳江高本底地区和对照地区居民骨镭-226、镭-228的浓度分别为29.9pCi/kg, 26.9pCi/kgl 8.7pCi/kg, 8.2pCi/kg.由此估算出阳江高本底地区屠民骨中²²⁶Ra、²²⁸Ra的负薄璧及对骨衬、骨髓所产生的剂量当量分别为对照地区民民的3.4倍, 3.3倍。两地区居民内脏器官中^{210Po、210Pb的测定分析铡数较少但仍看出, 高本底地区均明显高于对照地区.}     

226Ra 228Ra 210Pb和210Po在水生生物及食物链中转移规律的探讨

目的 为了解天然放射性核素²²⁶Ra、²²⁸Ra、²¹⁰Pb与²¹⁰Po在水生物及食物链中转移和蓄积情况。方法 定点采集养殖水产品及栖息环境中水与底质沉积物, 按不同的实验需要, 每个鲜样分别剥取肉, 骨(壳),鳞片和胃肠。烹饪样品, 洗净、称重、清炖, 熟后分离出骨(壳),余为食物。样品分别测定²²⁶Ra、²²⁸Ra、²¹⁰Pb和²¹⁰Po含量。数据按统计学要求处理, 配对数据, 作了配对显着性检验。结果 ²²⁶Ra、²²⁸Ra和²¹⁰Pb主要沉积于骨(壳)中, 浓集系数为10²～10³,肉中为10⁰～10².²¹⁰Po主要蓄积在水生物胃肠中, 浓集系数在10²～10⁴,鱼类胃肠与贝类肉中可达10⁴.水产食品烹饪加工过程²²⁶Ra、²²⁸Ra和²¹⁰Pb在食物链中转移不明显, 经配对显着性检验, 差异无显着性(P0.05);然而210Po在淡水鱼类和虾类中转移是明显的, 肉配对检验有非常显着性差别(P<0.01).结论水生物对²²⁶Ra、²²⁸Ra、²¹⁰Pb和²¹⁰Po有很强浓集能力。     

Production of large quantities of 90Y by ion-exchange chromatography using an organic resin and a chelating agent

The performance of a system composed of an organic cation exchanger (Dowex 50Wx8) and a chelating agent (EDTA) previously described for the successful production of (90)Y via a (90)Sr/(90)Y generator is assessed under dynamic conditions. In an attempt to overcome the established limitation of ion-exchange resins for the separation of subcurie quantities of activity, (90)Y is repeatedly isolated from an 11.8-GBq (320 mCi) (90)Sr cow using a three-column tandem arrangement. The high recovery and radionuclidic purity obtained for (90)Y and the parameters of the separation (time, eluant concentration, pH and flow rate range) strongly suggest that Ci quantities of (90)Y can be handled satisfactorily by the ion-exchange method. No replacement or treatment of the cow, low waste generation and (90)Sr losses less than 0.1% after each run were observed during the present study which, in combination with the low cost of this resin, may result in an attractive alternate method for the production of large quantities of (90)Y.     

Radiobiological Issues in the Anomalous Enhanced Effect of Low-dose-rate Fission-spectrum Neutrons: Reply to Letter to the Editor by G. W. Barendsen

Summary

The influence of diet or its ingredients on ¹⁴¹Ce absorption and retention was investigated in six-day-old rats. Animals were fed over 8 h with cow's milk, rat diet or a mixture of rat diet ingredients (fish meal, sunfiower meal, alfalfa, cane molasses and premix) labelled with ¹⁴¹Ce. Whole-body radioactivity was determined in a double crystal scintillation counter every 24 h over a six-day period. Gut, liver, kidney and femur retention and cerium distribution in the gut was determined at the end of the experiment. Compared to milk diet, administration of rat diet or ingredients caused respectively 3 and 7·5 times lower whole body retention. Carcass retention was reduced by rat diet or ingredients 2–3 times and intestinal retention 3 and 8 times respectively. Irrespective of the dietary treatment the main site of cerium intestinal retention was the ileum. Our present results indicate that some compounds of rat diet might be considered as a means of reducing cerium absorption and intestinal retention in the very young.     

Rapid determination of Sr impurities in freshly “generator eluted” Y for radiopharmaceutical preparation

⁹⁰Y is one of the most useful radionuclides for radioimmunotherapeutic applications and has a half-life (t_1/2=64.14 h) suitable for most therapeutic applications, beta particles of high energy and decays to a stable daughter. It is significant that ⁹⁰Y is available conveniently and inexpensively from a radionuclide “generator” by decay of its parent, ⁹⁰Sr. Nevertheless, current and planned clinical applications with [⁹⁰Y] labelled compounds employ activity levels that cannot be readily obtained from an in-house generator, but from commercial sources. We have evaluated Eichrom's Sr-resin, either as an “in-house” generator or as a fast QC method for analysis of ⁹⁰Y solutions.In particular, for the development as a generator, we investigated the percentage of the radio-Sr in the first 8 M HNO₃ eluate: in this fraction the concentration of ⁹⁰Sr must be smaller than 10⁻⁵% (recommendations of the International Commission on Radiological Protection). For evaluation as a rapid QC method, we analyzed the concentration of ⁹⁰Y in all the fractions containing “only” radio-Sr: ⁹⁰Y should not be present in these eluates. After the collection of β⁻ and γ spectra and analysis of them, we concluded that commercial Sr-resin minicolumn cannot give us the results expected; we developed an in-house system loaded with 4 mL of Sr-resin which gave better results as a generator and a rapid QC method.     

Pre-therapeutic dosimetry and biodistribution of 86Y-DOTA-Phe1-Tyr3-octreotide versus 111In-pentetreotide in patients with advanced neuroendocrine tumours

Purpose For the internal radiotherapy of neuroendocrine tumours, the somatostatin analogue DOTATOC labelled with ⁹⁰Y is frequently used [⁹⁰Y-DOTA-Phe¹-Tyr³-octreotide (SMT487-OctreoTher)]. Radiation exposure to the kidneys is critical in this therapy as it may result in renal failure. The aim of this study was to compare cumulative organ and tumour doses based upon dosimetric data acquired with the chemically identical ⁸⁶Y-DOTA-Phe¹-Tyr³-octreotide (considered as the gold standard) and the commercially available ¹¹¹In-pentetreotide.Methods The cumulative organ and tumour doses for the therapeutic administration of 13.32 GBq ⁹⁰Y-DOTA-Phe¹-Tyr³-octreotide (three cycles, each of 4.44 GBq) were estimated based on the MIRD concept (MIRDOSE 3.1 and IMEDOSE). Patients with a cumulative kidney dose exceeding 27 Gy had to be excluded from subsequent therapy with ⁹⁰Y-DOTA-Phe¹-Tyr³-octreotide, in accordance with the directives of the German radiation protection authorities.Results The range of doses (mGy/MBq ⁹⁰Y-DOTA-Phe¹-Tyr³-octreotide) for kidneys, spleen, liver and tumour masses was 0.6–2.8, 1.5–4.2, 0.3–1.3 and 2.1–29.5 (⁸⁶Y-DOTA-Phe¹-Tyr³-octreotide), respectively, versus 1.3–3.0, 1.8–4.4, 0.2–0.8 and 1.4–19.7 (¹¹¹In-pentetreotide), with wide inter-subject variability. Despite renal protection with amino acid infusions, estimated cumulative kidney doses in two patients exceeded 27 Gy.Conclusion Compared with ⁸⁶Y-DOTA-Phe¹-Tyr³-octreotide, dosimetry with ¹¹¹In-pentetreotide overestimated doses to kidneys and spleen, whereas the radiation dose to the tumour-free liver was underestimated. However, both dosimetric approaches detected the two patients with an exceptionally high radiation burden to the kidneys that carried a potential risk of renal failure following radionuclide therapy.     

Comparison of extraarticular leakage values of radiopharmaceuticals used for radionuclide synovectomy

OBJECTIVES: Radionuclide synovectomy is a reliable therapy in patients with chronic synovitis. However, radiation doses delivered to non-target organ systems due to leakage of radioactive material from the articular cavity are an important disadvantage of this procedure. In this study we compared extraarticular leakage values of the 3 commonly used radiopharmaceuticals; 90Y-citrate, 90Y-silicate and 186Re-sulfide colloid. MATERIALS AND METHODS: Thirty-five patients with persistent synovitis were enrolled in the study. Twenty-two hemophilic, 8 rheumatoid arthritis and 5 patients with pigmented villonodular synovitis were studied. 90Y labeled silicate and citrate were used for knee joints and 186Re-sulfide for intermediate sized joints. Radiocolloid leakage values were evaluated using a gamma camera with 20% window centered over the bremsstrahlung photopeak of 90Y and a respective window over the 137 keV photopeak of 186Re. Regions of interest were drawn over the injection site, the regional lymph nodes and the background areas. Leakage of radiocolloid was calculated by dividing the counts/pixel in the regional lymph node area to the counts/pixel in the injection site. RESULTS: No visible leakage was observed. The median leakage values calculated for 90Y-citrate, 90Y-silicate and 186Re-sulfide were found as 1.9%, 2.4% and 2.7%, respectively. The difference between the variability of leakage values was not statistically significant (p > 0.05). CONCLUSION: There was no significant difference in terms of extraarticular leakage between 9Y-citrate, 9Y-silicate and 186Re-sulfide radiocolloids.     

Rapid synthesis and in vitro and in vivo evaluation of folic acid derivatives labeled with fluorine-18 for PET imaging of folate receptor-positive tumors

In an attempt to visualize folate receptors that overexpress on many cancers, [¹⁸F]-fluorobenzene and pyridinecarbohydrazide-folate/methotrexate conjugates ([¹⁸F]-1, [¹⁸F]-2-folates and [¹⁸F]-8, [¹⁸F]-9-MTXs) were synthesized by the nucleophilic displacement reactions using ethyl-trimethylammonium-benzoate and pyridinecarboxylate precursors. The intermediates ethyl [¹⁸F]-fluorinated benzene and pyridine esters were reacted with hydrazine to produce the [¹⁸F]-fluorobenzene and pyridinecarbohydrazides, followed by coupling with N-hydroxysuccinimide-folate/MTX. Radiochemical yields were greater than 80% (decay corrected), with total synthesis time of less than 45 min. Radiochemical purities were always greater than 97% without high-performance liquid chromatography purification. These synthetic approaches hold considerable promise as rapid and simple method for the radiofluorination of folate derivatives with high radiochemical yield in short synthesis time. In vitro tests on KB cell line showed that significant amount of the radioconjugates were associated with cell fractions, and in vivo characterization in normal Balb/c mice revealed rapid blood clearance of these radioconjugates with excretion predominantly by the urinary and partially by the hepatobiliary systems. Biodistribution studies in nude mice bearing human KB cell line xenografts demonstrated significant tumor uptake and favorable biodistribution profile for [¹⁸F]-2-folate over the other conjugates. The uptake in the tumors was blocked by excess coinjection of folic acid, suggesting a receptor-mediated process. Micro-positron emission tomography images of nude mice bearing human KB cell line xenografts confirmed these observations. These results demonstrate that [¹⁸F]-2-folate may be useful as molecular probe for detecting and staging of folate receptor-positive cancers, such as ovarian cancer and their metastasis as well as monitoring tumor response to treatment.     

Comparison of [18F]FDG-PET and L-3[123I]-iodo-alpha-methyl tyrosine (I-123 IMT)-SPECT in primary lung cancer

OBJECTIVE: The aim of this study was to evaluate L-3[123I]-iodo-alpha-methyl tyrosine (IMT)-SPECT and FDG-PET in pulmonary lesions suspected to be lung cancer. METHODS: Whole body PET (measured transmission corrected emission scans) was performed 45 minutes after i.v. injection of 222-370 MBq (6-10 mCi) 18F-FDG on a Siemens PET scanner (ECAT EXACT 47) including 5-6 bed positions. 123I-IMT-SPECT (chest) was performed after injection of 370 MBq (10 mCi) with a dual head camera (Picker Prism 2000) and commercially available reconstruction algorithms. Ten patients (6 male and 4 female) with suspected lung cancer were investigated. The results were compared to histological findings after surgery or bronchoscopic biopsies and CT. RESULTS: 123I-IMT-SPECT and FDG-PET were able to detect all 9 cases of lung cancer (1-8 cm in diameter). One case was true negative. Both imaging methods were true positive with respect to mediastinal lymph node metastases in one patient. The tumor/background ratio was higher with PET (8.20 vs. 2.84). CONCLUSION: Despite the limited number of patients it may be concluded that IMT-SPECT as well as FDG-PET are suited to correctly diagnose lung cancer. Nevertheless, FDG-PET, if available, seems to be better suited because of the higher tumor/background ratio and better resolution.     

Repeated 0.5-Gy γ-ray irradiation attenuates autoimmune manifestations in MRL-lpr/lpr mice

Purpose: MRL-lpr/lpr mice, a model for various autoimmune diseases, were repeatedly irradiated with 0.5 Gy of γ-rays, and changes in their autoimmune manifestations were investigated.

Materials and methods: MRL-lpr/lpr mice at 13 weeks of age were maintained in plastic cages and exposed whole-body to 0.5 Gy γ-ray irradiation from a ¹³⁷Cs source 5 times per week for 4 weeks, from the time they were 13 weeks old until they reached 17 weeks old. Changes of autoimmune manifestations were examined 3 weeks later at the 20th week.

Results: Splenomegaly, lymphadenopathy, and proteinuria in MRL-lpr/lpr mice were clearly ameliorated by a total dose of 10 Gy (0.5 Gy/day×5 days/week for 4 weeks). Histologically severe disease-specific damage to the kidney and the salivary gland, i.e., glomerulonephritis and sialoadenitis, was also improved after irradiation. CD3⁺ CD4^? CD8^? CD45R/B220⁺ T cell numbers, which proliferate abnormally in MRL-lpr/lpr mice, were significantly decreased by the irradiation, possibly through induction of apoptosis. The elevated NO₂^? and NO₃^? (NO_x^?) production by macrophages of MRL-lpr/lpr mice was lowered by the irradiation. The irradiation also prolonged the life span of MRL-lpr/lpr mice. These phenomena may contribute to the amelioration of autoimmune manifestations in MRL-lpr/lpr mice exposed to repeated small-doses of γ-rays.

Conclusions: Repeated small-dose γ-ray exposure ameliorates the autoimmune manifestations in MRL-lpr/lpr model mice.