放射治疗射野任意点剂量自动计算的实现

本文介绍了放射治疗射野任意点剂量自动计算的实现方法。此方法完成模拟定位机下对患者治疗野图像的识别与任意点剂量的计算。     

复杂放疗射野模拟定位方法的改进研究

目的 :改进复杂放疗射野的模拟定位方法,以提高放疗定位工作效率。方法 :利用数字化治疗影像(digital therapy imaging,DTI)工作站和光学投影原理,测量标尺框架投影距离,更改模拟定位机治疗单元,对放疗射野缩放和打印,实现复杂放疗射野的投影定位。结果:简化了放疗射野定位流程,提高了放疗射野的适形程度,大幅缩短了复杂放疗射野的定位时间,减少了患者所受的辐射剂量。结论:该方法简单、易行、可靠,适合临床应用和推广。     

MatriXX系统结合TLD测量电子线全身放疗射野剂量参数的研究

目的探讨二维空气电离室矩阵MatriXX系统与热释光剂量计（TLD）相结合,测量电子线全身放疗（ETBI）射野剂量参数的可行性。方法用MatriXX系统、固体水模块、仿真人体模型及TLD,测量ETBI射野的百分深度剂量曲线、单野输出剂量和6个不同角度射野照射后的剂量累积因子。结果按照1mm递增测出了ETBI射野的百分深度剂量曲线及ETBI剂量计算所需要的各种校正因子。结论MatriXX系统与TLD相结合测量ETBI射野的剂量学参数非常简便、高效,是ETBI测量的理想工具。     

MatriXX二维电离室阵列的剂量特性研究

目的:在加速器X线、电子线射野条件下,通过测量和计算的方法研究MatriXX二维电离室阵列的剂量学特性,为调强放疗计划的剂量验证提供依据.方法:用MatriXX测量X线、电子线射野,研究其剂量线性、重复性和剂量率响应;用计算和测量相比对的方法,研究MatriXX多叶光栅射野的平面剂量分布.结果:MatriXX有良好的剂量线性、重复性,无剂量率依赖性;多野光栅射野较大时,计算和测量的剂量分布一致性较好,但在射野边缘和剂量梯度大的区域,计算和测量的结果一致性较差.结论:MatriXX可用于调强放疗计划的剂量验证,对于剂量梯度较大区域的剂量验证需要进一步研究.     

双种群遗传算法优化射野方向及权重的研究

目的:研究双种群遗传算法在同时优化射野方向和射野权重中的应用。方法:建立基于三维光子笔射束的IMRT剂量计算模型,用VisualC#.Net编写剂量计算并实现双种群遗传算法优化射野方向和权重的算法,分析优化结果。结果:在射野较少的情况下射野方向的微小变化可以使靶区剂量分布更加适形,且高剂量区域更大,用双种群遗传算法同时优化射野方向和权重,能够在一个临床可接受的计算时间内得到较高适形度的剂量分布。结论:在射野较小的情况下,射野方向的改变对剂量的分布有很大的影响。双种群遗传算法是一种有效的随机全局优化方法,它的并行性、全局性、鲁棒性使得方向和权重两个具有复杂耦合关系的量能够同时优化。双种群遗传算法在IMRT计划优化中具有广阔的应用前景。     

改变测量模体源皮距在大面积射野调强验证中的应用

目的 探讨改变测量模体源皮距（SSD）在大面积射野调强验证中的应用效果。方法 选取2018—2022年医院收治的15例鼻咽癌Ⅱ期患者作为研究对象，均接受放射治疗。先行CT模拟定位，然后将图像传输至Monaco治疗计划系统，物理师按照医师要求设计治疗计划，计算所有射野在模体中的剂量分布，并传输至验证系统进行分析，将所有射野角度设置为0°，在SSD为90、91、92、93、94、95、96、97、98、99、100 cm时分别进行模拟照射，运用软件分析相对剂量γ通过率。结果 当SSD为93、94、95、96、97、98、99 cm时，γ通过率均≥95.0%，当SSD为90、91、92、100 cm时，γ通过率均<95.0%。结论 大面积射野的调强验证可通过改变SSD大小实现，建议SSD设置在93～99 cm范围内。     

电子线靶区剂量计算软件的设计和实现

本研究通过实测建立了射野大小与输出剂量关系的数学模型,用VB程序设计语言开发了电子线靶区剂量计算的软件系统,软件模块包括射野输出因子和百分深度剂量(PDD)数据库、输入参数模块、计算模块、结果显示模块、软件容错模块等。系统开发完成后,用实测数据验证其计算结果的准确性,用极限条件及非常规数据验证软件的容错性及对异常数据的处理功能。测试结果表明,本研究开发的电子线靶区剂量计算软件计算结果准确、界面简洁、输入方便、容错性好,具有临床应用价值。     

数字化AGFA设备在放射治疗中的应用

<正>肿瘤放疗进入了“精确定位、精确计划、精确治疗”的新时代,为此,不断加强肿瘤放疗的质量控制和质量保证就显得尤为重要。摆位误差的测量是其中一个重要的方法,它需将治疗位置图像与模拟定位的图像进行比较。目前应用的射野验证方法有:①电子射野影像系统     

放射治疗实时二维治疗计划系统的设计

本文介绍了一种放射治疗实时二维治疗计划系统的设计。此系统完成模拟定位机下定位图像动、静态采集、处理，实时完成对患者治疗 定位与剂量点的计算。     

CT模拟定位技术研究

利用CT模拟定位技术可为靶区的确定。复杂多野照射，适形调强放疗以及立体定向立体定向放射治疗提供更多的信息和更高的定位精度，CT模拟定位技术贴近实际临床放疗。可以取代传统的X光定位形式，能提高定位精度和治疗计划的准确性。提高放射治疗质量。具有很大的现实意义与广阔应用前景，本文对CT模拟定位技术中涉及到的图像融合，三维可视化技术，激光定位技术，射野设计和三维剂量计算等关键技术予以介绍。     

基于ImageJ的伽马刀质量控制检测技术的应用研究

目的:基于ImageJ图像处理软件,制定一套实用性强、准确可靠的γ刀检测分析方法,以解决γ刀检测中的胶片分析问题。方法:利用ImageJ图像处理软件,并结合宏命令(macro)编写脚本程序,对γ刀检测的胶片图像进行分析,分别实现胶片剂量标定、机械等中心与辐射野等中心的偏差、照射野尺寸、半影宽度等关键参数的分析与计算。结果:胶片剂量标定中,用不同的拟合函数建立胶片的灰度-剂量曲线,对于EBT3胶片,多项式拟合和Devic方法均能取得可接受的拟合结果,相关系数r²>0.99;利用图像处理方法对等中心偏差的结果进行了验证,偏差≤0.05 mm;辐射野尺寸和半影宽度的计算结果与γ刀厂家的分析软件得到的结果具有较好一致性,二者偏差<1 mm。结论:制定的γ刀检测分析方法可为γ刀质量控制检测工作提供技术支撑,提高检测结果的准确性与可靠性。     

X线图像引导放射治疗设备性能评价标准考虑的主要问题

该文简要阐述了在放射治疗领域使用的X线图像引导放射治疗(X-IGRT)设备的定义和分类,并结合医药行业标准YY 1650-2019《X射线图像引导放射治疗设备性能和试验方法》,分析了X-IGRT设备的辐射野尺寸和靶点引导范围,以及摆位校正计算的准确性,讨论了X-IGRT摆位校正计算的准确性影响因素,目的是帮助同行了解X-IGRT设备性能评价标准,掌握X-IGRT设备性能评价的指标要求和试验方法,以期在评价X-IGRT设备性能时达成一致。     

Results of the study of typhoid vaccines in four controlled field trials in the USSR

In field trials of typhoid vaccine in the USSR, a comparison was made of the effectiveness of chemical, heat-killed, and alcoholized vaccines. All of them conferred protection if administered in sufficient dosage, and variations in effectiveness could usually be traced to size of dosage. The heat-killed vaccine, however, appeared to be significantly more effective than the others. The immunological history of a vaccinated person apparently had no essential influence on the effectiveness of a vaccine, and the data indicated that two doses of the vaccine conferred no greater protection than one.     

基于CT/MRI图像的三维近距离放射治疗计划系统

介绍了一个以CT/MRI序列图像为数据源的三维近距离放射治疗计划系统。系统区别于外照射治疗计划系统,为医生提供了具有三维动态剂量分布显示的交互式布源系统,并包括独特的模板库支持、精确快速的剂丘分布计算及实时显示和完备的计划评估预警系统等。此外,该系统还具有从数据采集到配准、分割、二维图像处理、三维重建、计划报告输出等一系列功能,并提供了友好的图形用户接口(GUI),完全适用于临床应用。该系统现已在临床试用,效果良好。     

Monte Carlo simulation of the effect of focal spot size on contrast-detail detectability

A contrast-detail experiment was simulated using Monte Carlo methods, to test the hypothesis that quantum limitations lead to an optimum minimum focal spot size below which no further improvement in image quality may be obtained. The simulation included a variable X-ray tube focal spot size, patient equivalent water phantom, X-ray couch, automatic exposure control, anti-scatter grid and indirect digital radiography detector. A number of simplifications were necessary in order to limit the calculation time to 8 days per image. Four images were produced for each focal spot size and these were scored by eight experienced observers. The contrast-detail curves were found to improve monotonically as focal spot size was reduced, with the best images produced by a point source. This contradicts the hypothesis of quantum limitation of focal spot size. We conclude that further work is required on the optimization of focal spot size. To assist with this, a new definition of system detective quantum efficiency is suggested, that includes the focal spot modulation transfer function, but does not include scattered radiation from the patient.     

A set of equipment for rapid roentgenography based on diffusion photographic materials

The authors describe a set of equipment for x-ray diagnosis based on diffusion photographic material, including an exposure cassette, an outfit for image processing and a portable impulse x-ray device. That the use of the roentgenographic set under outpatient or field conditions holds promise is determined by rapid production of an image, small size and weight of the set, convenience in operation and by the information content of the image obtained.     

An x-ray diagnostic unit based on a gas-discharge converter

The authors describe a pulse x-ray unit based on a gas-discharge luminescent converter, including a two-channel high-voltage impulse generator, an x-ray radiator, and a control desk. The high dosage sensitivity of the gas-discharge converter and large dimensions of the operating field as well as small size, mass and power consumption make it possible to use the unit for roentgenoscopic low-dose examination in the medical diagnosis under outpatient conditions.     

Film based scatter measurement in mammography

Film based measurements of scatter to primary ratio (s/p) have been made using the "beam stop" technique. Phantom material, radiographically equivalent to 100% glandular tissue, 100% adipose tissue and 50% glandular: 50% adipose tissue was used. These measurements have been made at 25 and 28 kVp for non grid and 28 and 30 kVp with grid for phantom thicknesses varying from 3 cm to 7 cm and 'D shaped' field sizes varying from 80 to 290 cm2. Results indicate that s/p is predominantly uniform across a mammographic image with a reduction towards the edge of the phantom. The values for s/p agree with previously published values determined from Monte Carlo calculation. Scatter primary ratio was found to be directly proportional to phantom thickness with little effect from field size. The effect of beam energy was significant in the non-grid case but reduced in significance with the use of a grid. The average measurement error was estimated at 4.5%. No variation in scatter primary ratio was detected between glandular and adipose phantom materials in this study.     

Investigation of photon beam models in heterogeneous media of modern radiotherapy

This study investigates the performance of photon beam models in dose calculations involving heterogeneous media in modern radiotherapy. Three dose calculation algorithms implemented in the CMS FOCUS treatment planning system have been assessed and validated using ionization chambers, thermoluminescent dosimeters (TLDs) and film. The algorithms include the multigrid superposition (MGS) algorithm, fast Fourier Transform Convolution (FFTC) algorithm and Clarkson algorithm. Heterogeneous phantoms used in the study consist of air cavities, lung analogue and an anthropomorphic phantom. Depth dose distributions along the central beam axis for 6 MV and 10 MV photon beams with field sizes of 5 cm x 5 cm and 10 cm x 10 cm were measured in the air cavity phantoms and lung analogue phantom. Point dose measurements were performed in the anthropomorphic phantom. Calculated results with three dose calculation algorithms were compared with measured results. In the air cavity phantoms, the maximum dose differences between the algorithms and the measurements were found at the distal surface of the air cavity with a 10 MV photon beam and a 5 cm x 5 cm field size. The differences were 3.8%. 24.9% and 27.7% for the MGS. FFTC and Clarkson algorithms. respectively. Experimental measurements of secondary electron build-up range beyond the air cavity showed an increase with decreasing field size, increasing energy and increasing air cavity thickness. The maximum dose differences in the lung analogue with 5 cm x 5 cm field size were found to be 0.3%. 4.9% and 6.9% for the MGS. FFTC and Clarkson algorithms with a 6 MV photon beam and 0.4%. 6.3% and 9.1% with a 10 MV photon beam, respectively. In the anthropomorphic phantom, the dose differences between calculations using the MGS algorithm and measurements with TLD rods were less than +/-4.5% for 6 MV and 10 MV photon beams with 10 cm x 10 cm field size and 6 MV photon beam with 5 cm x 5 cm field size, and within +/-7.5% for 10 MV with 5 cm x 5 cm field size, respectively. The FFTC and Clarkson algorithms overestimate doses at all dose points in the lung of the anthropomorphic phantom. In conclusion, the MGS is the most accurate dose calculation algorithm of investigated photon beam models. It is strongly recommended for implementation in modern radiotherapy with multiple small fields when heterogeneous media are in the treatment fields.     

正常成人总体蛋白质更新率及血浆甘氨酸动力学参数的测定

实验以~(15)N-甘氨酸为示踪剂,一次静脉内注射给药后,分别收集一定时间内血浆样品和尿样。血浆样品经一系列处理后,用气相层析-质谱联用仪(GC-MS)分析血浆中~(15)N-甘氨酸的丰度衰减情况,尿样经处理后,用同位素比值质谱计测定其中~(15)N丰度,并分别按不同的数学模型,计算出一系列动力学参数。实验测定了12例正常成人的总体蛋白质更新率为4.20±0.23(蛋白质g·d~(-1)·kg~(-1),合成速率为3.29±0.26(蛋白质g·d~(-1)·kg~(-1)),分解速率为3.06±0.25(蛋白质g·d~(-1)·kg~(-1)),其中10例的血浆甘氨酸更新率为3.02±0.46/h,血浆库容量为98.358±9.60μmol/kg,血浆甘氨酸流量为289.325±26.23(μmol·kg~(-1)·h~(-1))。