Kubicek心搏量公式的适用性

使用Kubicek公式计算心搏量和评价心功能是阻抗血流图的重要应用方向之一,目前已在我国广泛应用,并不断取得进展.本文从作为Kubicek心搏量公式理论基础的Nyboer公式开始,对Kubicek公式的适用性进行了讨论.并提出了在临床应用现状的条件下,应特别注意的三个问题:1 基础阻抗值Z0的影响;2 血液电阻率ρ不变3 dZ相似文献   

放疗分割剂量对食管癌细胞耐药基因表达的影响

目的:观察不同放疗剂量对食管癌细胞EC9706耐药基因MDR1表达水平的影响,同时分析其对细胞化疗耐药性的作用。方法:对食管癌细胞分别按常规剂量组(2 Gy/d.f)和小剂量组(1 Gy/d.f)进行分次外照射,共20次。采用实时定量PCR(QRT-PCR)和Western blot对外照射前后处于缺氧培养下的食管癌细胞MDR1表达水平进行检测。MTT实验评估化疗细胞抑制率。结果:照射前缺氧培养下的食管癌细胞MDR1表达水平即较对照组明显升高(P0.05)。接受20次2 Gy/d.f照射后食管癌细胞的MDR1表达水平明显高于单纯缺氧培养组(P0.05),但小剂量照射组的MDR1表达则明显减低(P0.05),同时其耐药指数亦明显下降(P0.05)。结论:同缺氧条件下进行常规剂量分次外照射相比,小剂量分次外照射可以缓解食管癌细胞的耐药程度,推测其辅助化疗疗效应较好。     

心阻抗血流图心搏量计算公式的问题

心阻抗血流图目前已在我国广泛应用，并不断取得进展。使用心搏量公式的计算结果评价心功能，是心阻抗血流图的重要应用方向之一。本文从作为Ｋｕｂｉｃｅｋ心搏量公式理论基础的并联阻抗模型和Ｎｙｂｏｅｒ公式开始，对Ｋｕｂｉｃｅｋ公式进行了讨论。并提出了在临床应用现状的条件下，应特别注意影响心搏量计算结果的两个问题：基础阻抗值Ｚ０的影响和血液电阻率ρ不变。     

心阻抗血流图电阻新公式与常用电阻公式的比较分析

本文是我们建立一种心阻抗血流图新理论的系列研究之三。本文根据文献［１，２］所得出心阻抗血流图新理论和电阻公式，通过数值计算，给出了电阻新公式与常用电阻公式的差别，分析了产生差别的原因；并对阻抗血流图中的电阻公式和我们提出的新公式进行了比较。     

公式法碘-131治疗Graves病甲亢甲状腺吸收剂量误差分析

目的:探讨公式法碘-131治疗Graves病甲状腺机能亢进症(甲亢)致甲状腺吸收剂量的误差。方法:对28例Graves病甲亢患者,采用超声计算甲状腺质量,并计算多时点测量甲状腺摄碘率(RAIU)、碘-131在甲状腺内有效半衰期(T_(1/2eff))、滞留时间(RT)。设碘-131计划量为3.7 MBq/g,根据RAIU_(24h)校正计算碘-131给药活度,依据RT计算该活度致甲状腺吸收剂量。采用t检验分析结果。结果:甲状腺质量为(34.0±21.4)g,RAIU_(24h)为(0.505±0.122),T_(1/2eff)为(3.56±0.92)d,RT为(2.98±1.03)d,公式法计算碘-131活度致甲状腺吸收剂量为(61.4±17.0)Gy,明显低于处方剂量75 Gy(t=-4.15,P0.01)。结论:临床上常用的计算碘-131活度方法致甲状腺吸收剂量明显低于处方剂量,误差较大,这主要与T_(1/2eff)较小且变异系数大有关。     

8种肾小球滤过率预测公式对肾细胞癌患者肾功能评价的适用性及相关因素分析

目的 评价8种常用的肾小球滤过率(GFR)预测公式对肾细胞癌患者肾功能评价的适用性,并分析影响预测公式的相关因素。方法 收集蚌埠医学院第一附属医院泌尿外科2017年1月—2018年12月收治的132例肾细胞癌患者的临床资料进行回顾性分析。记录患者术前测得的血清肌酐Scr值、年龄、性别、体质量指数(BMI)、有无合并症、肿瘤T分期等资料。以外源性放射标记物同位素⁹⁹Tc^m-二乙三胺五醋酸 (DTPA) 的肾排泄率所测得的GFR参照值(rGFR)为标准,应用Bland-Altman分析法比较以下8种预测公式计算得出GFR评估值(eGFR)的偏差:改良 MDRD-1、改良MDRD-2,CKD-EPI公式,联合血清肌酐与胱抑素 C的公式,Cockcroft-Gault (C-G) 公式,基于胱抑素 C的公式 1,基于胱抑素C的公式2,简化 MDRD公式。通过单因素分析方法分别观察患者性别、年龄、BMI、T分期及合并症等对不同预测公式的影响。结果 以rGFR为标准比较8种计算公式的95%一致性分析,胱抑素C相关的2种公式均低估了GFR实际水平,其余6种公式均不同程高估了GFR实际水平。eGFR值偏差较小的3种公式依次是CKD-EPI(7.74 mL/min)、血清肌酐与胱抑素 C(7.87 mL/min)以及改良MDRD-1公式(7.98 mL/min),界外百分比最低的3种公式依次为改良MDRD-2(1.98%)、改良MDRD-1(2.48%)、 C-G公式(2.97%);eGFR值偏差最大的公式为:改良MDRD-2(22.22 mL/min)。通过单因素分析显示8种公式计算的eGFR结果在不同性别、BMI及T分期的肾癌患者间差异均无统计学意义(P值均＞0.05)。除胱抑素C-1和胱抑素C-2两种公式计算结果外,其余6种公式计算的eGFR值在不同年龄段结果不同(随年龄的增高均减少),在合并症组较无合并症组低,差异均有统计学意义(P值均<0.05)。结论 CKD-EPI、联合肌酐胱抑素以及改良MDRD-1对于评价肾癌患者适用性较好,影响eGFR准确度的因素是多样的,患者年龄和是否存在合并症对预测公式的一致性影响较大。     

SRK II公式测量近视眼晶状体度数准确性的研究

目的 分析SRK II公式计算近视眼晶状体度数的准确性.方法 收集2004-2005年克拉玛依市中心医院眼科行准分子激光手术患者158例,共316眼,按不同眼轴及不同屈光度分组,两两比较各组晶状体度数.结果 同一眼轴长度组,不同屈光度组晶状体度数的差异具有显著统计学意义;同一屈光度组,眼轴较长组与眼轴较短组的晶状体度数没有明显差异.结论 SRK II公式计算近视眼晶体度数存在不足之处,尤其是眼轴影响较大.     

放射治疗后宫颈癌组织内差异表达基因鉴定

目的 研究放射治疗对宫颈癌组织基因表达的影响,探讨差异表达基因对放射治疗敏感及在抗拒中的作用.方法 患者接受相同的放疗模式:全盆腔外照射总剂量45戈瑞(Gy),共25次(45 Gy/25 f),腔内近距离内照射每次剂量5～6 Gy,共治疗5～6次.分别在近距离放射治疗前、近距离放射治疗中、近距离放射治疗结束时留取标本....     

不同分割剂量同步推量调强放疗治疗肺癌脑转移瘤的安全性分析

目的:分析不同分割剂量同步推量调强放疗治疗肺癌脑转移瘤的安全性及生存情况。方法:选取肺癌脑转移瘤患者75例,随机分为3组,均实施同步推量调强放疗,其中A组放疗方案为全脑40 Gy/20f（2.0 Gy/f）+瘤区同步推量46 Gy/20f（2.3 Gy/f）,B组方案为全脑40 Gy/20f（2.0 Gy/f）+瘤区同步推量52 Gy/20f（2.6 Gy/f）,C组方案为全脑40 Gy/20f（2.0 Gy/f）+瘤区同步推量58 Gy/20f（2.9 Gy/f）。放疗开始后,对3组患者危及器官（眼球、晶体、视神经、脑干）平均剂量及最大剂量和3组患者放疗相关不良反应进行比较。治疗结束后定期复查颅脑MRI评价疗效,观察3组患者1年生存率。结果:A、B、C组危及器官平均剂量及最大剂量差异不显著（P>0.05）;A、B、C组急性放疗不良反应发生率差异不显著（P>0.05）,晚期神经系统不良反应发生率亦差异不显著（P>0.05）,3级放疗不良反应低于5%,无4级放疗不良反应发生。随访1年,C组生存率高于A、B组（P<0.05）。结论:同步推量调强放疗治疗肺癌脑转移瘤是一种安全有效的方法,随着放疗剂量增加,疗效有增加趋势。     

NSD3促进组蛋白H3K36双甲基化抑制巨噬细胞中TNF-α的产生

目的主要研究巨噬细胞中核受体结合SET结构域蛋白3(NSD3)对脂多糖(LPS)触发的肿瘤坏死因子α(TNF-α)的调控作用,并探讨其调控机制。方法以小鼠腹腔巨噬细胞和RAW264. 7细胞作为细胞模型。100 ng/m L LPS刺激小鼠腹腔巨噬细胞,采用实时定量PCR检测NSD3 mRNA水平,Western blot法检测NSD3蛋白水平;在RAW264. 7细胞中过表达NSD3或采用RNA干扰技术敲低腹腔巨噬细胞中NSD3的表达,ELISA检测NSD3对LPS触发的TNF-α分泌的影响; Western blot法检测敲低NSD3对LPS触发的核因子κB p65(NF-κBp65)信号通路的影响;荧光素酶法检测NSD3对NF-κBp65介导的TNF-α基因转录活性的影响;染色质免疫沉淀实验检测TNF-α基因启动子区组蛋白H3的36位赖氨酸(H3K36)甲基化的募集。结果 LPS抑制巨噬细胞中NSD3的表达;过表达NSD3抑制LPS触发的TNF-α的产生,敲低NSD3则促进LPS触发的TNF-α的产生,但对NF-κB活化无影响; NSD3抑制NF-κBp65介导的TNF-α基因的转录活化,促进TNF-α基因启动子区的H3K36二甲基化。结论 NSD3促进TNF-α基因启动子区H3K36的双甲基化,抑制TNF-α的表达。     

放射生物学数学模型的研究进展

目的：放射生物学数学模型随着放射治疗的发展不断被提出,最早提出了L-Q模型和靶模型,由于靶模型形式较为复杂、参数较多,L-Q模型得到了广泛的应用。但是随着SRS、SBRT大剂量放疗的出现,越来越多的证据表明,L-Q模型在大剂量范围计算精度不高,尤其是从常规低剂量到大剂量。研究者提出了新的放射生物学数学模型。方法：本文按照模型被提出的时间顺序对L-Q模型、SH-MT模型、ML-Q模型、USC模型、gL-Q模型进行阐述。结果：ML-Q模型、USC模型、gL-Q模型与实验数据符合较好。结论 ：相比较而言,对于目前SRS、SBRT大剂量照射,USC模型和gL-Q模型可能更为适用,但USC模型和gL-Q模型的适用性和模型中的参数仍需进一步的确认。     

Hyperfractionation in advanced head and neck cancer.

This preliminary study was undertaken to observe tumour response and normal tissue tolerance to hyperfractionation. This study showed encouraging locoregional control rate in advanced head and neck cancer. Responses T4 tumors are poor and are prone to recur. This indicates that probably greater dose is needed to control T4 disease. We used 7920 cGy for T4 and late T3 status tumour. This dose is well tolerated by patients. Control of T4 tumours may further be increased by increasing total dose, but in view of inadequate clear cut numerical data of tissue tolerance derived by L-Q = Linear Quadratic formula which is still under clinical trial, further increase in total dose cannot be overemphasized. Longer follow up is necessary to assess the long term control rate and late tissue reaction. There is a need of randomized controlled clinical trial to compare hyperfractionation and conventional fractionation. In next phase we are undertaking randomized study of twice daily, daily and weekly fractionation in advanced head and neck cancer.     

螺旋断层放疗自适应技术的初步应用

目的：通过比较螺旋断层自适应计划与非自适应计划中危及器官的受照剂量体积,评估应用螺旋断层放疗减少周围正常组织受照体积的临床可行性。方法与材料：收集5例患者治疗过程中每完成5个分次剂量后在螺旋断层治疗机上采集的兆伏级CT（MVCT）图像并勾画肿瘤范围（GTV）并测量GTV的体积,评价GTV的体积变化。完成20个分次照射剂量后应用MVCT图像勾画缩减后的GTV并创建自适应计划,通过比较自适应计划与非自适应计划危及器官的体积剂量直方图（DVH）,评估自适应放疗的剂量学优势。结果：5例应用螺旋断层放疗自适应技术的病人的GTV在完成25个治疗分次后与治疗前比较均有明显的缩小（约为40%～60%）。三例肺癌患者接受20 Gy照射的同侧肺的体积平均减少了8.76%;两例盆腔患者接受40 Gy照射的小肠体积减少了1.48%;接受40 Gy照射的直肠体积减少了8.86%;接受45 Gy照射的膀胱体积减少了7.67%。而应用螺旋断层放疗系统实施自适应放疗技术平均只需要185.4min。结论：应用螺旋断层放疗的自适应技术减少周围正常组织的受照体积在临床上是可行的。     

重组人血管内皮抑素联合放疗对Lewis肺癌小鼠肿瘤生长及VEGF表达的影响

目的:研究重组人血管内皮抑素(rh-Endostatin,YH-16,恩度)对不同放射剂量治疗的Lewis肺癌小鼠肿瘤生长及血管内皮生长因子(VEGF)表达的影响。方法:制作Lewis肺癌细胞接种肿瘤的动物模型,并将60只模型小鼠随机分为5组:A,空白对照组(不予任何治疗);B,小剂量多次放疗组(1Gy/f,隔日一次,共4次);C,大剂量单次放疗组(4Gy/f,共1次);D,小剂量多次放疗联合恩度组(放疗前4天起每天右侧腹股沟区皮下注射恩度0.1ml,共15天,放射剂量为1Gy/f,隔日一次,共4次);E,大剂量单次放疗联合恩度组(放疗前4天起每天右侧腹股沟区皮下注射恩度0.1ml,共15天,放射剂量为4Gy/f,共1次)。分别给予上述处理后计算抑瘤率,并用免疫组化SP法测定各组VEGF的阳性表达率。结果:与C、E组比较,B、D组的抑瘤作用及VEGF表达下降明显(P<0.05),尤以D组抑瘤更强(P<0.05)、VEGF下降最多(P<0.05)。结论:放疗前使用恩度可使Lewis肺癌小鼠对放疗的敏感性增加,其机制可能与下调VEGF的表达有关。     

Biological dose volume histograms during conformal hypofractionated accelerated radiotherapy for prostate cancer

Radiobiological data suggest that prostate cancer has a low alpha/beta ratio. Large radiotherapy fractions may, therefore, prove more efficacious than standard radiotherapy, while radiotherapy acceleration should further improve control rates. This study describes the radiobiology of a conformal hypofractionated accelerated radiotherapy scheme for the treatment of high risk prostate cancer. Anteroposterior fields to the pelvis deliver a daily dose of 2.7 Gy, while lateral fields confined to the prostate and seminal vesicles deliver an additional daily dose of 0.7 Gy. Radiotherapy is accomplished within 19 days (15 fractions). Dose volume histograms, calculated for tissue specific alpha/beta ratios and time factors, predict a high biological dose to the prostate and seminal vesicles (77-93 Gy). The biological dose to normal pelvic tissues is maintained at standard levels. Radiobiological dosimetry suggests that, using hypofractionated and accelerated radiotherapy, high biological radiation dose can be given to the prostate without overdosing normal tissues.     

Gadolinium neutron capture brachytherapy (GdNCB), a new treatment method for intravascular brachytherapy

Restenosis is a major problem after balloon angioplasty and stent implantation. The aim of this study is to introduce gadolinium neutron capture brachytherapy (GdNCB) as a suitable modality for treatment of stenosis. The utility of GdNCB in intravascular brachytherapy (IVBT) of stent stenosis is investigated by using the GEANT4 and MCNP4B Monte Carlo radiation transport codes. To study capture rate, Kerma, absorbed dose and absorbed dose rate around a Gd-containing stent activated with neutrons, a 30 mm long, 5 mm diameter gadolinium foil is chosen. The input data is a neutron spectrum used for clinical neutron capture therapy in Studsvik, Sweden. Thermal neutron capture in gadolinium yields a spectrum of high-energy gamma photons, which due to the build-up effect gives an almost flat dose delivery pattern to the first 4 mm around the stent. The absorbed dose rate is 1.33 Gy/min, 0.25 mm from the stent surface while the dose to normal tissue is in order of 0.22 Gy/min, i.e., a factor of 6 lower. To spare normal tissue further fractionation of the dose is also possible. The capture rate is relatively high at both ends of the foil. The dose distribution from gamma and charge particle radiation at the edges and inside the stent contributes to a nonuniform dose distribution. This will lead to higher doses to the surrounding tissue and may prevent stent edge and in-stent restenosis. The position of the stent can be verified and corrected by the treatment plan prior to activation. Activation of the stent by an external neutron field can be performed days after catherization when the target cells start to proliferate and can be expected to be more radiation sensitive. Another advantage of the nonradioactive gadolinium stent is the possibility to avoid radiation hazard to personnel.     

Endoluminal beta-radiation therapy for the prevention of coronary restenosis after balloon angioplasty. The Dose-Finding Study Group

BACKGROUND: Beta radiation is effective in reducing vascular neointimal proliferation in animals after injury caused by balloon angioplasty. However, the lowest dose that can prevent restenosis after coronary angioplasty has yet to be determined. METHODS: After successful balloon angioplasty of a previously untreated coronary stenosis, 181 patients were randomly assigned to receive 9, 12, 15, or 18 Gy of radiation delivered by a centered yttrium-90 source. Adjunctive stenting was required in 28 percent of the patients. The primary end point was the minimal luminal diameter six months after treatment, as a function of the delivered dose of radiation. RESULTS: At the time of follow-up coronary angiography, the mean minimal luminal diameter was 1.67 mm in the 9-Gy group, 1.76 mm in the 12-Gy group, 1.83 mm in the 15-Gy group, and 1.97 mm in the 18-Gy group (P=0.06 for the comparison of 9 Gy with 18 Gy), resulting in restenosis rates of 29 percent, 21 percent, 16 percent, and 15 percent, respectively (P=0.14 for the comparison of 9 Gy with 18 Gy). At that time, 86 percent of the patients had had no serious cardiac events. In 130 patients treated with balloon angioplasty alone, restenosis rates were 28 percent, 17 percent, 16 percent, and 4 percent, respectively (P=0.02 for the comparison of 9 Gy with 18 Gy). Among these patients, there was a dose-dependent enlargement of the lumen in 28 percent, 50 percent, 45 percent, and 74 percent of patients, respectively (P<0.001 for the comparison of 9 Gy with 18 Gy). The rate of repeated revascularization was 18 percent with 9 Gy and 6 percent with 18 Gy (P=0.26). CONCLUSIONS: Intracoronary beta radiation therapy produces a significant dose-dependent decrease in the rate of restenosis after angioplasty. An 18-Gy dose not only prevents the renarrowing of the lumen typically observed after successful balloon angioplasty, but actually induces luminal enlargement.     

Estimation of the dose at the maze entrance for x-rays from radiotherapy linear accelerators

Recent measurements have shown that the NCRP formula to estimate the x radiation dose at the maze entrance of high energy radiotherapy rooms underestimates the dose by an order of magnitude. In the present work the Monte Carlo Code MCNP was used to model a radiotherapy room and investigate the NCRP formula. The dose of the scattered photons was calculated for 6-MV and 10-MV x-rays for the following situations: primary beam in vacuum, primary beam with air in the room, collimated primary beam (by the jaws) with air in the room and primary beam collimated with air in the room, and phantom at 100-cm SSD. It was found that for 6-MV x-rays the dose, when these materials were present in the beam path, was 1.2, 1.6, 5.3, and 13.1 x 10(-22) Gy photon(-1), respectively. Therefore the presence of all these materials together increased the dose by a factor of 11. The dose due to leakage was calculated separately to be 9.1 x 10(-22) Gy photon(-1). This adds another factor of 8. The 10-MV results were similar to those at 6 MV. There was good agreement between MCNP calculations and the published measurements. The spectrum and average energy of scattered photons at different locations in the radiotherapy room and the maze were also calculated by MCNP.     

基于PARTER开展肿瘤Flash-RT研究——设计及计算

闪光放疗（Flash-RT）是近年来国际肿瘤放疗研究的前沿科技和研究热点,其使用超大剂量率（通常大于100 Gy/s） 在极短时间（1~50 ms）内将全部放疗剂量注入靶区。研究发现其对正常组织体现出更小的损伤,同时可呈量级地降低放 疗时间。中国工程物理研究院太赫兹自由电子激光装置上的超导电子加速器可提供最高平均流强5 mA的6~8 MeV电 子束流,基于它的先进放疗研究平台（PARTER）具有Flash-RT研究的潜力。本文首次介绍PARTER及详细的Flash-RT专 用靶和准直器物理设计方案,并给出关键参数的蒙特卡罗模拟计算结果。根据设计,平台上生物样品内注入的最高剂量 率达2 000 Gy/s,剂量注入时间从μs到百ms持续可调,100 Gy/s以上剂量率覆盖深度超过20 cm,符合Flash-RT研究要求。 文中给出了详细的计算过程和结果分析,以提供给之后在PARTER上开展Flash-RT实验研究作为基本参考数据。