辐射剂量和染色体不稳定畸变的量效关系

目的:探讨辐射剂量和染色体不稳定畸变的量效关系.方法:应用4MV X线对离体淋巴细胞进行0、0.5、1、2、3、4、5、6Gy的辐射.进行淋巴细胞培养3天后,染色体分析,计数100个细胞的双着丝粒、着丝粒环、无着丝粒断片.统计分析辐射剂量和畸变染色体数目的量效关系.结果:0、0.5、1、2、3、4、5、6Gy的辐射后染色体畸变发生率为0%、6%、15%、41%、72%、148%、231%、382%,拟合曲线为Y=12.582X2 -15.387X+9.715.结论:染色体不稳定畸变发生率随辐射剂量增加呈二次多项式关系增加.     

早熟凝集染色体环法在山西太原事故受照射者生物剂量估算中的应用

目的： 探讨药物诱导的早熟凝集染色体环 (prematurely condensed chromosomes ring,PCC-R)分析方法在辐射事故受照射者生物剂量估算中的应用。方法：山西太原辐射事故发生后16 h收集5名受照射者 (1、2、3、4和5号)的外周血,及1号受照者照射后23 h的骨髓细胞和24 h的外周血,采用冈田酸 (Okadaic acid,OA)诱导的PCC方法计数PCC细胞中的PCC-R,以新建立的PCC-R剂量-效应曲线 (1～20 Gy)估算生物剂量。照射后31 d对4名受照射者 (2～5号)的PCC-R频率进行了分析。并采用常规染色体双加环 (dic+r)、胞质分裂阻滞微核 (cytokinesis-block micronuclei,aCBMN)分析及物理方法对PCC-R法的结果进行验证。结果：最严重受照射者1号的外周血培养仅获得极少量的PCC细胞,而骨髓培养获得了一定数量的PCC细胞。以骨髓细胞PCC-R频率对1号及以外周血PCC-R频率对2～5号进行剂量估算的结果分别为12.4、3.6、3.2、1.7和1.5 Gy。2～5号受照者照后31 d PCC-R频率与照后16 h相比下降幅度分别为51%、69%、69%及44%。结果与用dic+r、CBMN分析及物理方法估算的剂量接近,与临床表现基本相符。结论：经实际应用证明,药物诱导的PCC-R法简便、快速,新建立的PCC-R剂量-效应曲线准确、可靠。该法更适用于较高剂量照射的生物剂量估算,且应在照后尽早取血,最好在1个月之内。     

辐射剂量和染色体不稳定畸变的量效关系

目的：探讨辐射剂量和染色体不稳定畸变的量效关系。方法：应用4MVX线对离体淋巴细胞进行0、0．5、1、2．3、4、5、6Gy的辐射。进行淋巴细胞培养3天后,染色体分析,计数100个细胞的双着丝粒、着丝粒环、无着丝粒断片。统计分析辐射剂量和畸变染色体数目的量效关系。结果：0、0．5、1、2、3、4、5、6Gy的辐射后染色体畸变发生率为0％、6％、15％、41％、72％、148％、231％、382％,拟合曲线为Y=12．582X^2-15．387X＋9．715。结论：染色体不稳定畸变发生率随辐射剂量增加呈二次多项式关系增加。     

用染色体涂染方法对早先辐射受照人员进行回顾性照射剂量估算

背景与目的:探索用染色体涂染(painting)技术回顾性估算早先辐射受照人员照射剂量的可行性.材料与方法:用不同剂量(0～5.00 Gy)的60Co γ射线照射正常人外周血,用1、2和4号染色体涂染探针分析染色体易位,建立辐射诱发的染色体易位率剂量.效应曲线.用同样的方法分析3例早先受60co γ射线照射人员的染色体易位,参照剂量.效应曲线估算剂量,与照射后当时估算的生物剂量比较;并对1例无照射当时的生物剂量病例进行回顾性剂量估算.结果:用painting方法分析0～5.00 Gy 60Co γ射线诱发的全基因组易位率均随着吸收剂量的增加而增高,吸收剂量和全基因组易位率之间的剂量.效应曲线均为二次方程模式,曲线方程为γ=0.043D2 0.006D 0.0036.3例早先受照人员的估算剂量与照射后生物剂量的资料基本一致,另1例早先受照人员的估算剂量与照后当时物理模拟剂量一致.结论:本研究建立的painting方法可用于早先受辐射照射人员的回顾性剂量估算.     

辐射诱导染色体畸变的快速FISH方法的建立

目的： 建立一种检测辐射诱导染色体畸变的快速荧光原位杂交(FISH)方法。方法：两步简并引物PCR法扩增人α-卫星DNA,制备荧光基团直接标记的泛着丝粒探针;对60Coγ射线照射后的人外周血淋巴细胞染色体标本进行FISH分析,荧光显微镜下检测着丝粒及染色体形态。结果：直接标记泛着丝粒探针杂交后显示所有染色体着丝粒均有较强的信号;应用制备的FISH探针检测到γ射线照射诱导的双着丝粒、着丝粒环和易位染色体畸变,37 ℃杂交5-12 h后经过简单的洗涤即可在荧光显微镜下检测到较好的信号。结论：本研究制备的直接标记泛着丝粒探针,可用于FISH快速检测辐射诱导的染色体双着丝粒体、着丝粒环和易位畸变。     

P-32持续低剂量率辐射对外周血淋巴细胞染色体的损伤研究

目的:探讨P-32持续低剂量率辐射对外周血淋巴细胞的染色体损伤.方法:应用不同活度(0、0.01、0.1、0.5、2.7MBq)的放射性P-32胶体溶液,加入6ml的外周血淋巴细胞培养液中,培养3天后进行染色体分析.结果:0.01、0.1、0.5 MBq的P-32持续低剂量率辐射均造成染色体不稳定畸变(双着丝粒、着丝环、无着丝粒断片),随放射性活度增加而增加;2.7MBq的P-32辐射剂量较大,染色体形成率很低.结论:0.01、0.1、0.5 MBq的P-32持续低剂量率辐射可以造成染色体不稳定畸变,随辐射剂量增加畸变率增加;2.7MBq P-32的辐射剂量过大,染色体形成率很低不利于染色体畸变分析.     

提前获取早熟凝集染色体环快速估算受照剂量的可行性研究

目的：缩短培养时间,拟合γ射线诱发离体人外周血淋巴细胞早熟凝集染色体环（premature condensation chromosomerings,PCC-R）的剂量-效应曲线,探讨快速估算生物剂量的可行性。方法：~（60）Coγ射线照射离体人外周血,剂量为0、1、3、6、10、15、20 Gy,照后分别培养44和48 h,收获前1 h加入冈田酸,分别计数PCC-R频率,拟合受照44与48 h的剂量-效应曲线并进行比较。结果：培养44 h较48 h获得的分析细胞数略少,PCC-R率略低于48 h结果（各个剂量点间的差异均无统计学意义）。外周血淋巴细胞PCC-R率随照射剂量的增加而增加,0～15 Gy剂量范围内二者之间满足直线方程Y=-0.015 2＋0.062 5D（R~2=0.983 9）。结论：缩短培养时间至44 h,PCC-R仍然可以用于15 Gy以内的辐射事故的剂量估算。     

双色荧光原位杂交检测放疗后鼻咽癌患者外周血淋巴细胞染色体畸变

目的 :评价辐射诱发的染色体畸变作为癌患风险评估指标的可行性。方法 :应用双色荧光原位杂交 (FISH)技术检测 10例放疗后及 6例放疗前鼻咽癌患者外周血淋巴细胞染色体畸变并与常规法比较。结果 :放疗后 1～ 10年 ,鼻咽癌患者淋巴细胞染色体易位率、双着丝粒体率仍显著高于放疗前对照组的相应数值 (P <0 .0 0 1)。患者的易位率约为双着丝粒体率的 3 .5倍 ,照后 3年以上患者染色体易位率与照后小于 3年患者的易位率之间差别无显著性 (P >0 .1) ,而照后 3年以上患者染色体双着丝粒体率显著低于照后小于 3年患者的双着丝粒体率 (P <0 .0 0 1)。 结论 :稳定性染色体畸变 (易位 )在照后相当长时间 (10年 )仍可保持较高百分率 ,有望成为癌患风险评估的生物标志。     

辐射诱导酵母细胞延迟的遗传不稳定性

目的: 探讨辐射诱导酵母细胞延迟的遗传不稳定性是否与特定的染色体改变有关,这些克隆是否发生了延迟的染色体内重组频率及延迟的染色体畸变频率的增加,以便帮助鉴别引起遗传不稳定性的基因或外基因子.方法:酵母细胞受不同剂量γ射线照射,采用变交电场凝胶电泳技术,检测了受照细胞第58代克隆体延迟的遗传不稳定性.结果:Rsy-112未受照细胞的重组频率范围为2.7×10{-4}～4.6×10{-4},平均值为3.5×10{-4};受照细胞剂量在0.4 kGy～4.0 kGy之间的重组频率范围为2.8×10{-4}～11.7×10{-4}和3.9×10{-4}～35.3×10{-4},平均值分别为5.9×10{-4}和19.4×10{-4}.结论:辐射能够诱导酵母细胞延迟的遗传不稳定性,克隆细胞出现染色体内重组频率明显增加,核型发生了不同改变,主要为显带丢失、重组、分离及出现新的显带.     

碳离子辐照诱导人外周血淋巴细胞染色体畸变的时间和剂量效应

目的：研究碳离子辐照诱导淋巴细胞染色体畸变的时间和剂量效应。方法：以加速的碳离子为辐射源,吸收剂量分别为2、4Gy的碳离子辐照人外周血淋巴细胞后,分别培养48、72、84h后收集细胞,用姊妹染色单体区别染色法分析淋巴细胞第一次分裂中期染色体畸变,以研究畸变的时间效应;吸收剂量为0、0.5、1、2、3、4Gy的碳离子辐照人外周血淋巴细胞后,培养48h,用常规染色体技术研究碳离子辐照诱导淋巴细胞染色体畸变的剂量效应。结果：辐照后分别培养48、72和84h得到的双着丝粒和着丝粒环畸变（＂双＋环＂畸变）频率没有明显差异;在0.5～4Gy剂量范围内,＂双＋环＂畸变的量效关系符合线性关系：Y=0.0005＋0.689D。结论：在本实验辐照条件下,碳离子辐射诱导淋巴细胞染色体畸变不存在时间效应,可以用48h的培养时间来研究碳离子的生物学效应,并发现染色体＂双＋环＂畸变随剂量的增加而呈线性增加。     

KRAS基因突变与分化型甲状腺癌131I 放疗耐受性及预后的关系

[摘要] 目的：探究KRAS基因突变与分化型甲状腺癌（differentiated thyroid carcinoma,DTC）131I 放疗疗效和预后的相关性,并阐明其可能的机制。方法：收集经131I 放射治疗DTC临床组织样本,聚合酶链反应-单链构象分析法（single strand conformation polymorphism analysis of polymerase chain reaction products,PCR-SSCP）检测KRAS的遗传突变;采用qPCR 和Wb检测p21 蛋白的表达水平;亚致死剂量的131I 放射治疗DTC细胞系,采用CCK-8、流式细胞术（FCM）、Transwell 实验检测细胞活力的变化,并通过动物模型验证。结果：131I 放射治疗耐受DTC患者的KRAS基因突变增加（P<0.01）,KRAS基因突变导致p21 蛋白表达下调（P<0.05）,且与DTC临床分期及预后较差相关（P<0.05,P<0.01）。体内外实验证明,亚致死剂量的131I 放射治疗导致DTC细胞KRAS基因的突变率增加、p21 蛋白的表达水平降低,导致DTC细胞产生131I 放射耐受,而超表达KRAS基因显著提高p21 的表达,抑制肿瘤增长及转移。结论：KRAS基因突变与DTC临床分期及131I 放射耐受相关,亚致死剂量131I 放射治疗DTC促进KRAS基因突变产生放射耐受,而超表达KRAS基因能够提高DTC对131I放射治疗的敏感性。     

The presence of BRAF point mutation in adult papillary thyroid carcinomas from atomic bomb survivors correlates with radiation dose

In papillary thyroid carcinogenesis, the constitutively activated mitogen-activated protein (MAP) kinase signaling pathway caused by a genetic alteration such as RET/PTC rearrangement or mutation of RAS and BRAF genes, is thought to be a major early event. Among these, the recently identified BRAF(V600E) mutation has been found at high frequency in adult patients with papillary thyroid carcinoma (PTC). However, the association between this mutation and radiation exposure in adult PTC is still unknown. In this study, we examined the BRAF(V600E) mutation in 64 PTCs among adult atomic bomb survivors in Hiroshima, Japan, comprising 17 nonexposed (0 mGy) and 47 exposed patients who developed the carcinoma after the bombing, and assessed the association of BRAF(V600E) mutation with clinico-pathological and epidemiological variables. The median radiation dose in PTCs with the BRAF(V600E) mutation was significantly lower than that without the mutation (18.5 vs.156.9 mGy, Wilcoxon rank-sum test, P=0.022). A significant difference was found in the median latency period (years elapsed from atomic bombing to diagnosis) between exposed patients with and without BRAF(V600E) mutation (29 vs. 21 yr, Wilcoxon rank-sum test, P=0.014). These findings were further confirmed by logistic regression analysis with BRAF(V600E) mutation status as a dependent variable and taking into account possible interactions between the variables. We found that the log-transformed radiation dose and latency period were independently associated with the BRAF(V600E) mutation (P=0.039 and P=0.010, respectively). These results suggest that involvement of BRAF mutation in thyroid carcinogenesis in exposed people may differ from that in the nonexposed people.     

Geometric and dosimetric evaluations of an online image-guidance strategy for 3D-CRT of prostate cancer

PURPOSE: To evaluate an online image-guidance strategy for conformal treatment of prostate cancer and to estimate margin-reduction benefits. METHODS AND MATERIALS: Twenty-eight patients with at least 16 helical computed tomography scans were each used in this study. Two prostate soft-tissue registration methods, including sagittal rotation, were evaluated. Setup errors and rigid organ motion were corrected online; non-rigid and intrafraction motion were included in offline analysis. Various clinical target volume-planning target volume (CTV-PTV) margins were applied. Geometrical evaluations included analyses of isocenter shifts and rotations and overlap index. Dosimetric evaluations included minimum dose and equivalent uniform dose (EUD) for prostate and gEUD for rectum. RESULTS: Average isocenter shift and rotation were (dX,dY,dZ,theta) = (0.0 +/- 0.7,-1.1 +/- 4.0,-0.1 +/- 2.5,0.7 degrees +/- 2.0 degrees ) mm. Prostate motion in anterior-posterior (AP) direction was significantly higher than superior-inferior and left-right (LR) directions. This observation was confirmed by isocenter shift in perspectives AP (1.8 +/- 1.8 mm) and RL (3.7 +/- 3.0 mm). Organ motion degrades target coverage and reduces doses to rectum. If 2% dose reduction on prostate D(99) is allowed for 90% patients, then minimum 3 mm margins are necessary with ideal image registration. CONCLUSIONS: Significant margin reduction can be achieved through online image guidance. Certain margins are still required for nonrigid and intrafraction motion. To further reduce margin, a strategy that combines online geometric intervention and offline dose replanning is necessary.     

胃癌中p16基因缺失与突变的研究

目的：探讨p16基因外显子2的缺失和突变与胃癌发生发展的关系.方法：应用新鲜组织标本基因组DNA抽提、PCR-SSCP分析的方法,对30例胃癌及癌旁组织中p16基因外显子2的缺失和突变进行检测.结果：胃癌组织样本中p16基因外显子2的缺失率为10.00%,突变率为10.00%,两者之和为20.00%,癌旁组织样本中未发现缺失和突变,统计学分析有显著性差异（P〈0.01）.结论：p16基因外显子2的缺失和突变与胃癌的发生具有一定的相关性.     

立体定向放射治疗技术在前列腺增生症治疗中的应用探索

目的：观察立体定向放射治疗（X刀）前列腺增生症（BPH）的有效性及安全性。方法：应用X刀治疗12例重度BPH，靶区为整个前列腺，采用90％的等剂量曲线包绕靶区，（1．5—2）Gy／f，共（5—8）f，隔日一次，每周3次。治疗前、后比较国际前列腺症状评分、生活质量指数、前列腺体积、膀胱残余尿量、最大尿流速。结果：临床治愈8例，显效4例，各项指标变化显著（P〈0．01）。结论：立体定向放射治疗BPH安全、有效。     

Radiation therapy for recurrent esophageal cancer after surgery: clinical results and prognostic factors

Objective: To evaluate the outcome of radiotherapy for recurrent esophagealcancer after surgery and to determine the prognostic factors. Methods: From 1987 through 2002, 82 patients treated with radiotherapyfor loco-regional recurrences of esophageal cancer after surgerywere retrospectively reviewed. The stage at initial surgerywas I in 16, II in 41, III or higher in 24 and unknown in 1.The median size of recurrent tumors was 3.5 cm in diameter.Fifty-two patients were treated with radiotherapy alone, and30 were treated with radiotherapy combined with chemotherapy.The median total dose of external radiotherapy given was 50.4Gy in 28 fractions. Results: The median survival period after recurrence was 7.0 months.The 2- and 5-year overall survival rate for all patients was22 and 11%, respectively. In univariate analysis, the patientswith performance status (PS) = 0–1, or tumor size <3.5cm, and those treated with total dose 50 Gy showed a bettersurvival outcome than each the other groups. The patients witha history of previous radiotherapy showed a poorer survivaloutcome in univariate analysis than each the other groups. Inmultivariate analysis, tumor size, PS and radiation dose wereindependent prognostic factors for overall survival. Conclusion: The prognosis of patients with post-operative loco-regionalrecurrence of esophageal cancer is poor. However, a long-termsurvival may be expected by definitive radiotherapy for thepatients with small-size tumors and with a good PS.     

Hybrid IMRT for treatment of cancers of the lung and esophagus

PURPOSE: To report on a hybrid intensity-modulated radiation therapy (IMRT; static plus IMRT beams treated concurrently) technique for lung and esophageal patients to reduce the volume of lung treated to low doses while delivering a conformal dose distribution. METHODS: Treatment plans were analyzed for 18 patients (12 lung and 6 esophageal). Patients were treated with a hybrid technique that concurrently combines static (approximately two-thirds dose) and IMRT (approximately one-third dose) beams. These plans were compared with conventional three-dimensional (3D; non-IMRT) plans and all IMRT plans using custom four- and five-field arrangements and nine equally spaced coplanar beams. Plans were optimized to reduce V13 and V5 values. Dose-volume histograms were calculated for the planning target volume, heart, and the ipsilateral, contralateral, and total lung. Lung volumes V5, V13, V20, V30; mean lung dose (MLD); and the generalized equivalent uniform dose (gEUD) were calculated for each plan. RESULTS: Hybrid plans treated significantly smaller total and contralateral lung volumes with low doses than nine-field IMRT plans. Largest reductions were for contralateral lung V5, V13, and V20 values for lung (-11%, -15%, -7%) and esophageal (-16%, -20%, -7%) patients. Smaller reductions were found also for 3D and four- and five-field IMRT plans. MLD and gEUDs were similar for all plan types. The 3D plans treated much larger extra planning target volumes to prescribed dose levels. CONCLUSIONS: Hybrid IMRT demonstrated advantages for reduction of low-dose lung volumes in the thorax for reducing low dose to lung while also reducing the potential magnitude of dose deviations due to intrafraction motion and small field calculation accuracy.     

Factors associated with radiation-induced nausea and vomiting in head and neck cancer patients treated with intensity modulated radiation therapy

BACKGROUND AND PURPOSE: To investigate factors associated with radiation-induced nausea and vomiting (RINV) in the setting of head and neck intensity modulated radiation therapy (IMRT). MATERIALS AND METHODS: Forty-three patients treated with IMRT for head and neck cancer between 2002 and 2007 comprise the cohort. The majority (79%) were treated with an accelerated altered fractionation scheme, and concurrent chemotherapy was delivered to 23. A retrospective review of factors associated with nausea was performed. RESULTS: Eighteen patients (42%) reported grade 1 acute nausea, and seven patients (16%) reported grade 2 nausea. Factors significant for grade 1-2 nausea on univariate analysis included dose to the dorsal vagal complex of the mid-medulla, younger age, use of a low neck field, and Amifostine use. Only young age retained significance on multivariate analysis. High-grade nausea was associated with use of Amifostine (p=0.003) and concurrent chemotherapy (p=0.015). CONCLUSIONS: In addition to previously recognized emetic factors, young age and radiation dose to the dorsal vagal complex of the brainstem may play a role in development of nausea during head and neck IMRT.     

Retreatment of the spinal cord with palliative radiotherapy

We conducted this retrospective review of patients whose spinal cord was irradiated twice to evaluate the outcome in terms of palliation and long-term side effects.

Eight patients (4 females, 4 males; median age: 67 years) were identified whose spinal cord had been irradiated twice between July 1990 and July 1997, usually for the management of bone metastases. All patients were followed up until their death from progressive disease. The Karnofsky performance score at the time of retreatment ranged from 20% to 90%. Total dose for the first treatment ranged from 29 to 50 Gy (median: 38 Gy) with single doses 1.25–3 Gy; the total dose for the retreatment ranged from 29 to 38 Gy (median: 30 Gy) with a single dose 1.8–4 Gy. The cumulative dose ranged from 59 to 88 Gy (median: 67.5 Gy). The overlap in the site of retreatment consisted of 1–3 segments, whereas in one patient, 2 single segments were treated twice. The outcome in terms of progressive disease, the palliative effects, and the development of myelopathy was assessed retrospectively.

The median interval to reirradiation was 30 months (range: 6–63 months), and the median follow-up after the last treatment was 16 months (range: 5–44 months). After reirradiation, 4/7 patients experienced complete pain relief, 2/7 patients experienced minor pain relief, and only 1 patient showed no change. Two patients with paraparesis experienced complete recovery. All patients tolerated retreatment very well. No serious acute side effects requiring any therapy were seen. During follow-up, no patient showed treatment-induced neurologic abnormalities affecting motor and sensory function, and all patients were able to walk and were continent for stool and urine.

On the basis of the findings in this limited number of patients, it is not possible to give clear and general recommendations concerning the optimal total dose and fraction size that will have maximal palliative effects and minimal side effects. However, for the purpose of palliation, retreatment within the dose range used at our institution should be considered, taking the patient’s expected life span and clinical symptoms into account.