非均匀人形体模及医用诊断X线工作人员的有效剂量当量估算

本文根据ICRP有效剂量当量的概念,应用所研制的人干骨,干粉模拟软组织非均匀人形体模,求出了胃肠检查和胸透时医用诊断X线工作人员的器官剂量、有效剂量当量与个人剂量计读数的比值,也计算了它们与工作人员所在位置自由空气照射量率的比值。得出男女性别不同的医用诊断X线工作人员的有效剂量当量与佩戴在左胸的个人剂量计读数的比值,胃肠检查时分别为0.52和0.43,胸透时分别为0.32和0.21。应用这些比值和个人剂量监测数据估算了该类人员的有效剂量当量。     

乳腺仿真体模在超声专业住培教学中的应用

分析使用乳腺仿真体模在超声专业规培教学中的可行性。方法：选取2018年12月在杭州市第一人民医院培训的规培生作为实验组、进修生作为对照组,将乳腺仿真体模应用于规培教学,并进行进阶式理论及操作手法培训。通过操作考试、理论考试、课后问卷调查等方式进行教学效果分析。结果： 本研究实验组21人,对照组8人。培训后理论考试成绩实验组为68.10±8.14,对照组为50±12.24,两者有显著统计学意义。在同一年级不同阶段考试中,不同次的操作分数差异有统计学意义(F=106.59 P=0.00),问卷调查中100%学员认为在相关学习中获益。讨论：乳腺体模应用于超声规培教学的优点在于授课时便于规培医生理解解剖关系,方便男生进行敏感部位练习操作手法；缺点在于病变图像及位置固定,不利于高年级的业务能力提升。     

A novel realistic three-layer phantom for intravascular ultrasound imaging

Intravascular ultrasound (IVUS) is an imaging modality that experienced a tremendous development over the last 20 years. Phantoms for IVUS are rare and poorly documented. The aim of this paper is to propose an original IVUS phantom that has geometries and specular textures closer to those of coronary arteries than conventional tube-like phantoms. The proposed phantom has a three-layer aspect, reproducing the intima, media and adventitia that compose the arterial wall. It is made of an agar-based compound, with water, glycerol and cellulose particles. Fourteen phantoms were quantified using IVUS. Six phantoms were evaluated by both photomacroscopy and IVUS. There was an excellent correlation between phantom dimensions evaluated by photomacroscopy and the nominal values (mold dimensions). The IVUS quantification of the phantom was closely correlated to the measurements obtained by photomacroscopy. These results demonstrate that a multilayer phantom, with known and reproducible dimensions and with realistic geometric and echographic properties has been developed.     

新型胸部CT参考体模的实验研究

作者报道新型胸部CT参考体模的实验研究和制作。本体模是按中国人体参数设计,高分子材料制成,对X线、γ线的吸收和散射与人体组织有相似特性,具有心、肺、骨骼、肌肉、脂肪和皮肤,是CT诊断、放射治疗、放射防护、教学和辐射剂量标准等研究的重要实验工具,可作为人的替身使用。CT研究结果显示,本新型胸部CT参考体模的解剖形态仿真,组织密度等效,同真人相似,由4或5个横断面组装成形,是一种多功能新型胸部CT参考体模,在放射科质量保证(qualityassurence,QA)和质量控制(quality control,QC)中有重要的理论和实用价值。作者对其临床应用和操作技术进行了讨论。     

Radionuclide left ventricular volume determination. Influence of scattered radiation and surrounding activity

Summary. Radionuclide measurements of left ventricular volumes, ejection fractions and stroke volumes were performed by an equilibrium technique in nine patients using left anterior oblique projection and individual depth correction. Phantom studies were made in order to evaluate attenuation and scattering of the radiation. It was found that a simple depth correction factor, k(d)= e^μd, can be used under certain conditions. However, the determination of left ventricular volume by radionuclide techniques is not a truly absolute method. The depth correction factor to be used is dependent on the condition of measuring and evaluation, for instance how the region of interest for the left ventricle is selected. Therefore, this method should be carefully standardized, evaluated and compared to other techniques. Stroke volume measured by radionuclide and dye-dilution technique showed a correlation coefficient of 0·76 (nine patients) at rest and 0·77 (seven patients) at work. This method can be easily performed during routine ejection fraction determination and can thus be useful in clinical studies.     

运用彩色多普勒流速剖面图测定血流量的实验研究

运用实验血流模型，检测新近开发的彩色多普勒血流速度部面图（velocityprofile，VP）对血流量测定的准确性，并与脉冲型多普勒（PulsedwaveDoppler，PWD）测定法比较。结果显示在不同流速下两种方法的流量测值与实际流量间均有高度相关性，相关系数r分别为0．999（P＜0．001）和0．988（P<0．02）。但测得流量与实际流量之间的误差程度，VP法为-7.64～2．79％，PWD法为17.82～27.97％。表明VP法较PWD法更接近实际情况。     

Versatile,Reusable, and Inexpensive Ultrasound Phantom Procedural Trainers

We have constructed simple and inexpensive models for ultrasound‐guided procedural training using synthetic ballistic gelatin. These models are durable, leak resistant, and able to be shaped to fit a variety of simulation scenarios to teach procedures. They provide realistic tactile and sonographic training for our learners in a safe, idealized setting.     

数字X线摄影辐射剂量与图像质量相关性的实验研究

目的:前瞻性研究不同X线辐射剂量与图像质量的相关性,以探索数字X线摄影(Digital radiography,DR)最适宜曝光量.方法:在仿真胸部体模中放置模拟网状、线状和结节病变结构.用125 kVp不同mAs,对体模及分辨率测试卡进行DR成像.4位放射陕师分别对所有图像进行阅片评分,同时测量入射体表剂量(Entrance surface dose,ESD)、均方根(Root mean squar,RMS)和空间分辨率.结果:ESD随着mAs的增加会增加,而RMS随着mAs的增加会降低;ESD增加至一定量时,空间分辨率达到极限值.曝光指数(Exposure index,EI)值1800以下的图像模拟微小结节显示不清,EI值2000以上的图像对模拟病变的检出高.结论:在保证DR图像质量的前提下,最优化的曝光剂量可以有效地减少辐射损伤.     

Calculation of MRI-induced heating of an implanted medical lead wire with an electric field transfer function

PURPOSE: To develop and demonstrate a method to calculate the temperature rise that is induced by the radio frequency (RF) field in MRI at the electrode of an implanted medical lead. MATERIALS AND METHODS: The electric field near the electrode is calculated by integrating the product of the tangential electric field and a transfer function along the length of the lead. The transfer function is numerically calculated with the method of moments. Transfer functions were calculated at 64 MHz for different lengths of model implants in the form of bare wires and insulated wires with 1 cm of wire exposed at one or both ends. RESULTS: Heating at the electrode depends on the magnitude and the phase distribution of the transfer function and the incident electric field along the length of the lead. For a uniform electric field, the electrode heating is maximized for a lead length of approximately one-half a wavelength when the lead is terminated open. The heating can be greater for a worst-case phase distribution of the incident field. CONCLUSION: The transfer function is proposed as an efficient method to calculate MRI-induced heating at an electrode of a medical lead. Measured temperature rises of a model implant in a phantom were in good agreement with the rises predicted by the transfer function. The transfer function could be numerically or experimentally determined.