一例192Ir源放射事故病人的物理剂量估算和测量

目的早期快速对遭受１９２Ｉｒ源局部大剂量外照射一例病人的病情作出判断。方法利用组织－空气比方法计算躯干内及手部、腿部受照部位及其周围组织的剂量分布，并计算全身剂量。利用手表红宝石作为事故剂量计测量手部剂量。结果给出了手部、腿部受照部位及其周围组织的剂量分布，全身造血干细胞活存计权等效剂量为２．９Ｇｙ。病人手腕处红宝石剂量为１４．２Ｇｙ。结论病人全身剂量在中度骨髓型放射病范围内，手部、腿部受到局部大剂量照射。     

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。     

国产血管内^192Ir线源的放射剂量测定

目的 对国产血管内^192Ir线源的剂量分布进行评价，为动物实验和临床应用提供依据。方法 采用KodakX-omatV慢感光胶片，从平行和垂直于放射源长轴方向进行测量，径向测量时间为25、45、65和82s，轴向测定时间为25s，同时进行标准剂量的标定，通过胶片自动分析测量系统分析剂量分布和吸收剂量。参考AAPM TG No.60报告，采用Monte Carlo方法对放射源和辐射剂量进行理论计算，同时与采用AAPM TG No.43报告计算方法进行比较。结果 国产血管内^192Ir线源具有良好的剂量分布。AAPMTGNo.43报告计算方法比Monte Carlo方法高估32％的辐射剂量。结论国产^192Ir线源作为血管内放射源是可行的，采用慢感光胶片测定放射源的剂量分布是一种有效手段。     

电离室灵敏体积对调强放射治疗剂量学验证准确性的影响

目的研究电离室灵敏体积对调强放射治疗绝对剂量验证的影响。方法将调强治疗计划移植到重建的数字化体模上计算吸收剂量，对单个照射野和整个计划，分别在等中心点、最大剂量点以及剂量梯度大和剂量分布均匀的区域选取一些有代表意义的剂量点，用0．6、0．125和0．015cc电离室在固体水体模中分别测量各点的吸收剂量，并与TPS计算值进行比较。结果等中心和剂量分布均匀区域，各电离室测量值与计算值的相对误差均在5％范围内；最大剂量点和剂量梯度较大区域，0．6cc电离室误差达到8％和12％，小体积电离室误差较小。结论0．6和0．125cc电离室可用于剂量梯度较小处的绝对剂量验证，在最大剂量点和剂量梯度大的区域，误差较大，0．015cc电离室较适用于调强放射治疗剂量验证。     

β源支架剂量分布的蒙特卡罗算法

目的 比较数值积分和蒙特卡罗方法计算的放射性支架的剂量率分布。方法 以3种有代表性的剂量点核函数为计算模型，计算支架的剂量率分布。结果 分别计算了中心面的径向，支架表面及离支架表面0.5mm处的轴向剂量分布，径向最大差异为1．5％，轴向的差异也有1．5％之内。结论 3种函数用数值积分和蒙特卡罗方法计算的剂量分布是一致的，蒙特卡罗方法可用来计算放射性支架的剂量分布。     

半身照射条件下以微核估计全身等效剂量可能性的探讨

作者探讨了半身照射条件下以微核（ＭＮ）率估计相当于全身一次均匀照射剂量的可能性，并与人体模型以相同条件照射后的剂量计算结果及临床反应相验证，结果显示：以ＭＮ率所估算的剂量与人体模型所计算出的相当于一次全身均匀照射的红骨髓干细胞活存计权剂量及临床反应基本一致，照后无或仅有白细胞、血小板计数的轻微下降，多数有恶心呕吐，可能与全腹照射有关。因此，在以下半身为主的高度不均匀照射条件下，ＭＮ检测所估计的生物剂量可用以表示全身等效剂量及反映全身损伤程度。     

数值模拟在民航飞行宇宙辐射防护中的应用研究

目的 研究简便可行的民航飞行人员所受宇宙辐射有效剂量的估算工具。方法用欧洲飞行航程剂量计算程序EPCARD计算民航飞行航程中的有效剂量和剂量率，计算结果与有关文献实测的数据进行对比分析。结果计算机估算系统计算的数据在多数航线上与实测数据较吻合，但实测数据由于实施人员不同、仪器不同及估算方法的差别，对同一时期同一条航线，实测结果差别较大。结论在飞行高度用简便的个人剂量计测定宇宙辐射的各种成分目前还相当困难。宇宙辐射有效剂量不能直接测量获得，而必须用计算的方法或是从接近实际剂量值的测量数据转换而来，因此计算机模拟系统是最简便实用的宇宙辐射有效剂量估算工具。     

探讨靶区处方剂量50%生成区域的平均γ值在Compass三维剂量验证中的应用

目的 探讨Compass剂量验证系统在基于模型计算剂量和基于测量重建剂量的容积旋转调强放射治疗（VMAT）计划验证中，使用50%靶区处方剂量区平均γ值作为计划验证参考指标的应用价值。方法 基于Compass剂量系统用两种方法对70例患者的VMAT计划进行剂量验证，得到每例VMAT计划验证中50%靶区处方剂量区的平均γ值和γ通过率，评估50%靶区处方剂量区的平均γ值在剂量验证中的应用价值。先将计划系统（TPS）计算得到的计划信息导入到Compass系统中，进行基于加速器数据模型的独立核算剂量计算，得到基于模型独立核算的三维剂量。再将每例患者的治疗计划在加速器下实测得到的计划通量通过Compass系统进行剂量重建，得到基于测量重建的三维剂量。将两种方法得到的三维剂量分布结果与TPS计算得到的结果进行比较。结果 结合γ分析误差设定条件为3%/3mm标准的γ通过率结果，对50%靶区处方剂量区的平均γ值进行评估，γ≤0.4为通过，0.4<γ≤0.6为临床可接受结果，γ>0.6为不通过。70例VMAT计划验证结果显示，基于模型独立核算和TPS计算结果具有较好的一致性，γ值均<0.6，其中γ≤0.4的67例，0.4<γ≤0.6的3例，γ通过率均>92%；基于测量重建体内三维剂量的结果略差于基于模型的计划结果，γ值均<0.6，其中γ≤0.4的35例，0.4<γ≤0.6的35例，γ通过率均>88%，其中68例通过率>90%，2例<90%，但都符合临床剂量验证要求。基于模型的独立核算剂量分布结果优于基于测量重建剂量的结果，差异有统计学意义（t=15.20、10.71，P<0.05）。结论 50%靶区处方剂量区的平均γ值可作为临床计剂量验证参考指标判断临床计划的可执行性，平均γ值结合γ通过率的综合结果共同对剂量验证进行评估更有说服力；基于模型的剂量验证省时省力，但需要与基于测量的验证方式相结合进行综合考虑，作为一种可靠的剂量验证方法应用到临床。     

非规范案例的辐射致癌病因概率计算：一例钚内污染工人…

结合一例钚内污染人员所患肘部恶纤维组织细胞瘤的辐射病因判断，提出非规范病例辐射致癌病因概率计算方法，作为示范。根据肿瘤的组织结构提出三种可能的靶细胞，通过现有剂量监测数据计算三种靶细胞的照剂量，再利用间接导出的相应的致癌超额相对危险系数计算肿瘤来自所受照射的病因概率，其结果因所选用的靶细胞，危险系数和计算模型而有很大不同，最大相差４个量级。由于这个病例情况比较复杂，因此作者提出的计算步骤可供计算其     

p（35）Be快中子辐射场生物剂量参数的测定

报道了ｐ（３５）Ｂｅ快中子、γ混合辐射场生物剂量参数，说明了采用双电离室方法测量ｐ（３５）Ｂｅ快中子时，剂量计算中有关因子和参数的确定原则和估算结果；给出了辐射场的中子／γ比，照射野内组织比释动能率分布，以及由比释动能率计算小鼠全身与局部照射和血液样品照射时的吸收剂量转换系数等剂量常参数；最后还对剂量测量的误差问题做了分析。     

CB微核法在忻州事故生物剂量估算中的应用

本文作者报道了在忻州放射事故中３４例受检者ＣＢ法微核的检测结果。同时，用本实验室建立的ＣＢ微核剂量效应曲线对上述受检者进行生物剂量估算，并与染色体畸变分析估算的剂量进行比较，结果两种方法估算的剂量基本一致。表明ＣＢ微核法是估算事故受照者所受剂量的一种较为理想的方法。     

Excerpts from Maintaining Radiation Protection Records. National Council on Radiation Protection and Measurements

This is the first of a three-part series of articles from a report by the NCRP, to be reprinted in successive issues of Radiology Management. The report offers practical recommendations for establishing a radiation safety program. Different aspects of record-keeping, an essential part of all radiation safety programs, will be highlighted in each article. The introduction and a chapter on the systematic generation of records are included in this issue.     

Potential future application with therapeutic agents

Several new approaches to radiation therapy with radionuclides have been discussed. Iron 55 is selectively utilized in the red cell developmental cycle and in therapeutic doses, can lower marrow and circulating erythrocyte levels with much smaller degrees of effect on other cell lines. A serious complication, noted in animal studies, is the induction of neoplasma, especially osteosarcoma. Selective irradiation of the cell nucleus is possible with 125IUdR. This results in highly efficient cell killing due to the highly concentrated region of ionization. High concentrations of densely ionizing radiation in the malignant cell may also be accomplished with 211At. The use of labeled liposomes is an additional approach to the delivery of intracellular irradiation. None of these approaches is applicable for the practical treatment of human malignancy at the present time. The importance of these approaches is their value as models for future development of methods that can provide highly selective radiation to target sites.     

辐射诱导小鼠外周血网织红细胞微核与骨髓嗜多染红细胞微核的 剂量-效应关系

目的 观察X射线照射后小鼠外周血网织红细胞微核(MN-RET)和骨髓嗜多染红细胞微核(MN-PCE)的变化,为探索快速、高通量的辐射生物剂量计奠定基础.方法 54只ICR雄性小鼠随机分为3组,每组18只,分别施予X射线全身照射,吸收剂量分别为0、0.5、1、2、4和5 Gy.在照射后24、48和72 h,分别采用流式细胞术(FCM)和人工镜检的方法,观察外周血MN-RET和骨髓MN-PCE的变化.结果 在0.5～5.0 Gy范围内,3个时间点外周血MN-RET和骨髓MN-PCE均随剂量的增加而升高,剂量-效应曲线可拟合成直线回归方程(t=10.26～25.77,P<0.05);外周血MN-RET和骨髓MN-PCE之间明显相关(r=0.986-0.996,P<0.05).结论 FCM检测MN-RET有望成为快速、高通量的辐射生物剂量计或辅助诊断方法.

Abstract：

objective To study the changes of reticulocyte micronueleus(MN-RET)from peripherai blood and polychromatic erythrocyte mieronucleUS(MN-PCE)from bone marrow in mice following exposure to X-rays in order to provide an experimental basis for exploring possible hish-throughput radiation biodosimeter.Methods Male ICR mice were whole-body irradiated with 0,0.5,1,2,4 and 5 Gy at a dose rate of 0.488 Gy/min.MN-RET from peripheral blood wag scored with FCM and MN-PCE from bone marrow was scored with manual microscopy at 24,48 and 72 h post-irradiation.Results Both MN-RET and MN-PCE rates increaged with doses in the range of 0-5 Gy at 24,48 and 72 h after WBI.The dose-response relationship can be fit with linear equations(t=10.26-25.77,P<0.05).The correlation coeffcients between MN-RET from peripheral blood and MN-PCE from bone mallow were highly significant(r=0.986-0.996,P<0.05).Conclusions In view of its simplicity,accuracy and high throughput capacity,FCM scoring of peripheral blood MN-RET may be a candidate for radiation biodosimetry,More work should be carried out on human specimens to investigate this possibility.     

Effect of low-dose X-ray irradiation on micronucleus formation in human embryo,newborn and child cells

Purpose: It is well known that a high-dose of ionizing radiation is sufficient to break DNA strands, which leads to elevated genotoxic risks; however, the risks associated with low doses of ionizing radiation remain unclear. In addition, there is little data about the effect of low-dose ionizing radiation on human-derived embryo, newborn and child cells. We investigated the frequency of micronucleus (MN) formation in these cells to understand the genotoxic effects of ionizing radiation.

Materials and methods: We irradiated the cells with X-rays from 0.02–2?Gy at a rate of 0.0635?Gy/min. After irradiation, we investigated the effect of low-dose X-ray irradiation on cellular viability and frequency of MN formation.

Results: Increases in MN formation were largely dose-dependent; however, there were no differences between controls and doses lower than 0.2?Gy, except in KMST-6 human transformed embryo cells.

Conclusion: We could not detect an obvious effect of low-dose X-ray irradiation at doses lower than 0.1?Gy. The embryonic cells were more sensitive to X-ray irradiation than newborn and child cells. The threshold for X-ray-induced MN formation appears to be in the range of 0.05–0.1?Gy in cultured human embryo, newborn and child cells.     

Radiation therapy technologist survey: state of Michigan.

A survey of institutions in Michigan utilizing megavoltage equipment demonstrated a shortage of certified radiation therapy technologists. The low number of such personnel who can be trained in the available approved programs in the state is barely sufficient to maintain the present level. Projections show a continued shortage and a need for more approved radiation therapy technology training programs.     

Out of the Basement and Into the Classroom: Pathways for Expanding the Role of Radiation Oncologists in Medical Student Education

PurposeTo characterize radiation oncologist involvement in undergraduate medical education at US academic medical centers and to incorporate these findings into practical pathways for greater and broader integration of radiation oncology (RO) into medical curricula.MethodsChairpersons and residency program directors at RO departments directly affiliated with a medical school were asked to describe all the ways in which radiation oncologists in their department are involved in medical student education, excluding their elective clerkship.ResultsOf 75 eligible departments, 49 responded (response rate 65.3%). Twenty departments (40.8%) reported that at least one faculty member participates in a curricular educational session on an oncology-related topic. Twelve (24.5%) of these sessions were focused specifically on RO. Twenty-one departments (42.9%) had faculty involved with organized clinical shadowing or preceptorship programs for first- and second-year medical students. Twelve departments (24.5%) described no involvement in the formal curricula at their local or affiliated medical school. Thirteen departments (44.8%) described participation in a medical school–organized residency fair, and 12 departments (41.4%) sponsor an RO interest group. Reported novel approaches to teaching included development of multidisciplinary clerkships or educational sessions that include RO concepts, guest lectures on RO during a required clerkship, organized extracurricular experiences such as an oncology seminar series, participation in special medical student enrichment programs, and sponsorship or initiation of an RO interest group.ConclusionThe minority of RO departments are involved in formal teaching of the medical student body at large. The approaches described herein should facilitate more robust involvement of radiation oncologists in all areas of undergraduate medical education.     

微核着丝粒的荧光原位杂交技术在辐射研究中的应用

微核分析因其在遗传毒理学和辐射生物剂量学中的广泛应用而受到人们关注。近年来,随着分子遗传学及荧光原位杂交(FISH)技术的发展,人们对微核有了进一步的认识。FISH技术能用于解释微核的形成机理、功能及微核的超微结构,并可用于辐射损伤的遗传学评价。     

The "Golden Age" of prostate brachytherapy: a cautionary tale

PURPOSE: To investigate the earliest attempts to use man-made isotopes for prostate brachytherapy. METHODS AND MATERIALS: Two radiogold brachytherapy programs were analyzed, using literature review and interviews of participants. RESULTS: Although (198)Au has been discredited as a source for permanent prostate brachytherapy, the major flaw in the reviewed programs was the misapplication of the isotope. CONCLUSIONS: Safe and effective implant programs are grounded in the sound application of brachytherapy principles. New brachytherapy procedures should arise from the collaboration of radiation oncologists, surgeons, physicists, radiobiologists, and radiation safety specialists.     

Biodosimetry using radiation-induced micronuclei in skin fibroblasts

Purpose:?We assessed micronuclei in dermal fibroblasts as a local biodosimeter for estimating accidental in vivo radiation exposure.

Materials and methods:?Male and female C3H/HeJ and C57Bl6 mice of four age groups (～11, 36, 60 and 99 weeks) received a single whole body dose of gamma radiation (0–10 Gy) and radiation-induced micronuclei per 1,000 binucleated cells were assessed in skin fibroblasts in their first division after isolation from biopsies taken on days 1 and 7 post irradiation. The method of generalized estimating equations was used for statistical analyses.

Results:?Total micronuclei were increased on day 1 in a dose-dependent manner in the range of 1–10 Gy, with no significant attenuation of response between day 1 and day 7 and no significant effect of gender. Between-strain differences were observed with C3H/HeJ mice showing lower background micronuclei and a slightly steeper dose response. Age affected only the background micronuclei (moderate increase with age). The model demonstrated that the assay yields ‘unbiased’ prediction of the dose between 0 and 7 Gy. Within this dose range, the predicted dose was found to be accurate within ±1.5–2 Gy. When the specificity is set to 95%, the assay can distinguish between unexposed and 2 Gy exposed mice with a sensitivity of around 60%. The sensitivity approached 100% when discriminating between unexposed mice and mice receiving doses equal to or greater than 4 Gy. The percentage of binucleated cells with micronuclei was shown to be useful as a simpler and slightly faster substitute for the total micronuclei count.

Conclusion:?Micronuclei in dermal fibroblasts isolated up to 1 week after irradiation can be a useful biodosimeter for local dose after accidental radiation exposure.