心脏介入诊疗患者辐射剂量和早期外周血细胞变化观察

心脏介入诊疗由于创伤小,效果好,临床广为使用。但由于患者需要直接暴露在X射线照射下接受一定剂量的X射线,对患者可能造成一定辐射影响。本文通过监测心脏介入诊疗患者X射线受照剂量、检测心脏介入诊疗患者血液系统的外周血细胞成分变化,了解辐射对患者血液系统的影响。     

心脏介入诊疗患者辐射剂量和早期外周血细胞变化观察

心脏介入诊疗由于创伤小,效果好,临床广为使用.但由于患者需要直接暴露在X射线照射下接受一定剂量的X射线,对患者可能造成一定辐射影响.本文通过监测心脏介入诊疗患者X射线受照剂量、检测心脏介入诊疗患者血液系统的外周血细胞成分变化,了解辐射对患者血液系统的影响.     

心脏介入诊疗患者辐射剂量和早期外周血细胞变化观察

心脏介入诊疗由于创伤小,效果好,临床广为使用.但由于患者需要直接暴露在X射线照射下接受一定剂量的X射线,对患者可能造成一定辐射影响.本文通过监测心脏介入诊疗患者X射线受照剂量、检测心脏介入诊疗患者血液系统的外周血细胞成分变化,了解辐射对患者血液系统的影响.     

心脏介入诊疗患者辐射剂量和早期外周血细胞变化观察

心脏介入诊疗由于创伤小,效果好,临床广为使用.但由于患者需要直接暴露在X射线照射下接受一定剂量的X射线,对患者可能造成一定辐射影响.本文通过监测心脏介入诊疗患者X射线受照剂量、检测心脏介入诊疗患者血液系统的外周血细胞成分变化,了解辐射对患者血液系统的影响.     

心脏介入诊疗患者辐射剂量和早期外周血细胞变化观察

心脏介入诊疗由于创伤小,效果好,临床广为使用.但由于患者需要直接暴露在X射线照射下接受一定剂量的X射线,对患者可能造成一定辐射影响.本文通过监测心脏介入诊疗患者X射线受照剂量、检测心脏介入诊疗患者血液系统的外周血细胞成分变化,了解辐射对患者血液系统的影响.     

心脏介入诊疗患者辐射剂量和早期外周血细胞变化观察

心脏介入诊疗由于创伤小,效果好,临床广为使用.但由于患者需要直接暴露在X射线照射下接受一定剂量的X射线,对患者可能造成一定辐射影响.本文通过监测心脏介入诊疗患者X射线受照剂量、检测心脏介入诊疗患者血液系统的外周血细胞成分变化,了解辐射对患者血液系统的影响.     

心脏介入诊疗患者辐射剂量和早期外周血细胞变化观察

心脏介入诊疗由于创伤小,效果好,临床广为使用.但由于患者需要直接暴露在X射线照射下接受一定剂量的X射线,对患者可能造成一定辐射影响.本文通过监测心脏介入诊疗患者X射线受照剂量、检测心脏介入诊疗患者血液系统的外周血细胞成分变化,了解辐射对患者血液系统的影响.     

心脏介入诊疗患者辐射剂量和早期外周血细胞变化观察

心脏介入诊疗由于创伤小,效果好,临床广为使用.但由于患者需要直接暴露在X射线照射下接受一定剂量的X射线,对患者可能造成一定辐射影响.本文通过监测心脏介入诊疗患者X射线受照剂量、检测心脏介入诊疗患者血液系统的外周血细胞成分变化,了解辐射对患者血液系统的影响.     

心脏介入诊疗患者辐射剂量和早期外周血细胞变化观察

心脏介入诊疗由于创伤小,效果好,临床广为使用.但由于患者需要直接暴露在X射线照射下接受一定剂量的X射线,对患者可能造成一定辐射影响.本文通过监测心脏介入诊疗患者X射线受照剂量、检测心脏介入诊疗患者血液系统的外周血细胞成分变化,了解辐射对患者血液系统的影响.     

医用诊断X射线工作者的眼部防护

X射线照射可引起受照者眼晶状体混浊。混浊的发生率及严重程度随受照剂量的增大而加重。通过加强对X射线的防护，降低受照剂量，可减少或阻止晶状体混浊的发生。笔者对地市以上和旗县以下两个不同区域的医用诊断X射线工作者眼晶状体混浊情况进行比较。     

介入诊疗中重要站立区域辐射剂量的测定与评价

目的 给出介入诊疗中重要站立区域的概念，测量这一区域辐射剂量的分布并分析其特点，为介入工作人员特别是第一术者的放射防护提出建议和理论依据。方法 在重要站立区域内，从距地面10cm处向上至180cm处，每10cm选取一个测量点，选用介入诊疗中比较常用的冠脉造影程序，分3种状态：①不使用床上、下防护屏。②使用床上、下防护屏。③使用床上、下防护屏和铅衣防护进行辐射剂量的测定。每实验点重复测量3次，取算术平均值，经刻度校正并折算为mGy／h。结果 成功测量3种状态下的相关数据并绘制介入诊疗中重要的站立区域剂量分布示意图。结论 对第一术者重要站立区域内的辐射防护在整个介入放射防护体系的建立中具有重要的地位，应足够重视这一区域的放射防护。要注意尽可能的联合选用多种防护手段，特别不要忽视上、下防护屏和铅衣的选用。建议在第一术者足踝前部放置一活动铅挡板，或把下防护帘延长至地面以保护下肢足踝部。     

DR床旁摄影辐射剂量分布规律的研究

目的：分析DR床旁机X线管周围辐射剂量的分布规律,指导操作人员及同室其他人员选择相对合理位置,减少辐射。方法：采用成人胸部床旁摄影参数,将DR床旁机球管正对水模进行多次曝光,以X线管焦点为中心选择2个辐射平面共40个测量点,使用辐射剂量仪记录每次曝光时各测量点的瞬时最大剂量值,取每个点的平均值作为该测量点的辐射剂量值。结果：①在X线管长轴与入射中心线平面,不同距离各测量点的辐射剂量值分别为：200、190、150、140、90、80、15μGy/h（50cm）,170、155、120、110、80、70、11.5μGy/h（100cm）和130、115、90、80、60、50、9.5μGy/h（150cm）;②在X线管短轴与入射中心线平面,不同距离各测量点的辐射剂量值分别为198、186、146、132、86、75、15μGy/h（50cm）,166、149、115、101、75、65、11.5μGy/h（100cm）和124、108、84、69、54、46、9.5μGy/h（150cm）;③入射中心线上距焦点100cm处辐射剂量均为350μGy/h。结论：DR床旁机X线管周围辐射剂量存在阴极侧大于阳极侧、距焦点距离越远辐射剂量越小和从入射中心线到X线管正后方两侧剂量逐渐减小的分布规律。     

Efficacy of Lower-Body Shielding in Computed Tomography Fluoroscopy-Guided Interventions

Purpose

Computed tomography (CT) fluoroscopy-guided interventions pose relevant radiation exposure to the interventionalist. The goal of this study was to analyze the efficacy of lower-body shielding as a simple structural method for decreasing radiation dose to the interventionalist without limiting access to the patient.

Material and Methods

All examinations were performed with a 128-slice dual source CT scanner (12?×?1.2-mm collimation; 120?kV; and 20, 40, 60, and 80?mAs) and an Alderson-Rando phantom. Scatter radiation was measured with an ionization chamber and a digital dosimeter at standardized positions and heights with and without a lower-body lead shield (0.5-mm lead equivalent; Kenex, Harlow, UK). Dose decreases were computed for the different points of measurement.

Results

On average, lower-body shielding decreased scatter radiation by 38.2% within a 150-cm radius around the shielding. This decrease is most significant close to the gantry opening and at low heights of 50 and 100?cm above the floor with a maximum decrease of scatter radiation of 95.9% close to the scanner’s isocentre. With increasing distance to the gantry opening, the effect decreased. There is almost no dose decrease effect at ≥150 above the floor. Scatter radiation and its decrease were linearly correlated with the tube current-time product (r ²?=?0.99), whereas percent scatter radiation decrease was independent of the tube current-time product.

Conclusion

Lower-body shielding is an effective way to decrease radiation exposure to the interventionalist and should routinely be used in CT fluoroscopy-guided interventions.     

“十”字封闭型介入防护装置的研制

目的 为介入放射学提供辐射安全保障,方法根据介入手术之特点、Ｘ射线辐射场的剂量２以及辐 护最优化的原则,按照射区与手术区屏蔽隔离的原理,设计制造通用组合式介入防护装置。结果 研制出三台防护装置,经三家医院三种没类型线机匹配使用一,证明其适用性,通用性与防护效果良好。结论 设计思路科学、可行,具有推广应用价值,可民甸的介入防护问题。     

Image noise in X-ray imaging caused by radiation scattering and source leakage, a qualitative and quantitative analysis

All irradiated objects in the vicinity of an imaging set-up increase the amount of scattered radiation. It is a well-known fact that if this radiation is allowed to impinge on the image collector it naturally degrades the image quality. It also causes problems with equipment characterisation, such as X-ray energy spectra measurements. However, it may not be a well-known fact that when a small radiation safety enclosure is used - common for industrial applications - this type of scattered radiation is astonishing large. In this work a quantitative and qualitative analysis has been carried out in an attempt to explain the origin of the problem, why it occurs and how it may be treated.The scattered radiation increases rapidly when the fractions of X-ray photons in the primary X-ray spectrum above the K-edges of the enclosure wall material increase. High-energy photons are scattered and/or will generate characteristic radiation in the enclosure wall material instead of being absorbed. For lead, which is commonly used as shielding and wall material, this noise becomes significant when tube potentials over 90-100 kV are used, since the K-edges for lead are 72-74 keV (Kα) and 85-87 keV (Kβ). Below tube potentials of 100 kV, the noise from scattered radiation is insignificant, even if the primary beam is wide enough to hit the enclosure walls. Above 100 kV it increases rapidly and for this application the number of scattered photons was 50% of the primary photons at 170 kV.In this particular case this problem was accentuated above tube potentials of 100 kV since the steel housing of the micro focal X-ray source used was penetrated by high-energy photons in unwanted directions. Collimation of the X-ray beam just in front of the X-ray source output window to narrow the solid angle of the primary X-ray beam to avoid direct radiation of the enclosure walls was not enough to suppress this scattered noise. A wider X-ray shield, covering the entire front of the X-ray source had to be applied. Other solutions to decrease scattered radiation would be the following: Increased internal shielding of the X-ray source is the first choice if the same possibilities for geometrical magnification of the imaged object are to be maintained. Increased distances to the enclosure walls and other objects inside, that is, to use larger enclosures or even separate X-ray chambers would also decrease scattered radiation. To line the enclosure with a series of X-ray shielding materials with K-edges at lower and lower energies is another alternative. The lowest K-edge material should be placed closest to the detector followed by the second lowest K-edge material etc., to effectively absorb backscatter and characteristic radiation from the enclosure walls. This would, however, be a rather expensive and complicated solution.     

低剂量CT肺动脉成像技术进展

CT肺动脉成像(CTPA)已成为评价肺栓塞(PE)主要影像技术,筛查及多次CTPA复查PE疗效等使辐射剂量增加,因此低剂量CTPA日益受到重视。低剂量CTPA采取多种措施:降低管电流和管电压最为简单有效;大螺距扫描通过缩短扫描时间降低辐射剂量;缩小扫描覆盖范围可降低边缘器官的辐射;前瞻性心电门控在固定期相扫描及迭代重建算法选择性去除噪声等均可降低辐射。低剂量意识对于降低辐射至关重要。     

Dose reduction in multidetector CT using attenuation-based online tube current modulation

OBJECTIVE: This study was designed to quantify the radiation dose saved by attenuation-based online tube current modulation applied to multidetector CT (MDCT) of the adult trunk as a function of effective milliampere-second (mAs) presets, sex, and body habitus. SUBJECTS AND METHODS. One hundred twenty patients underwent MDCT of the trunk (60 thoracic, 60 abdominal) with an attenuation-based online tube current modulation. Consecutive acquisitions at standard and two lower effective mAs presets were obtained in each patient. Mean percentage effective mAs reductions were compared for each effective mAs preset, taking into account sex and body mass index. RESULTS: Mean effective mAs reduction was 16.9% and 20.0% for the chest and the abdomen, respectively. Mean percentage effective mAs reductions were found to be significantly different for sex (chest, p = 0.003; abdomen, p = 0.002) but not significantly different for the different effective mAs presets or body mass index. CONCLUSION: Attenuation-based online tube current modulation used with MDCT should be considered as a secondary tool of radiation dose reduction because it saves as much as 20% of the radiation dose on the adult trunk, regardless of initial mAs preset. However, initial decreases of mAs presets by the physician should be considered the primary tool for radiation dose reduction.     

How does a non-optimal tube potential influence radiation dose to the patient in lumbar spine radiography?

IntroductionWhen comparing the radiation dose to the patient, the lumbar spine has one of the highest dose values in general radiography, therefore the procedure needs to be optimised. The aim of this study was to investigate the effect of a non-optimal tube potential (66 kV) during anteroposterior (AP) lumbar spine radiography on the radiation dose received by the patient compared with the radiation dose when an optimal tube potential (79 kV) is used, in accordance with European guidelines.MethodsThis retrospective study involved 100 patients referred for lumbar radiography in two different diagnostic departments. Half of the patients were admitted to a department which used optimal tube potential and the other half to the department which used non-optimal tube potential for AP lumbar spine radiography protocols. The height and weight of the patients were collected to calculate the body mass index (BMI) of the patients. The image field size and dose area product (DAP) values were collected after each imaging session. The effective dose and selected organ dose were calculated using the PCXMC 2.0 program.ResultsThe results showed that a non-optimal tube potential resulted in a significant increase in the DAP value by 360% (p < 0.001) and a significant increase in the effective dose by 160% (p < 0.001). Dose to selected organs due to non-optimal tube potential increased from 107% (breasts) up to 631% (prostate) (p < 0.001). The images were not assessed using visual grading characteristics (VGC) analysis, but the radiologists evaluated all the images appropriate for diagnostic reading.ConclusionBased on our study's stated results, we can conclude that optimal tube potential use is essential to achieve the ALARA principle.Implications for practiceThe study shows the effect of a non-optimal tube potential on the radiation dose received by the patient during radiography of the lumbar spine. This could influence possible diagnostic departments to consider protocol optimisation due to the high radiation dose received by the patient.     

Do metallic endoprostheses increase radiation dose associated with automatic tube-current modulation in abdominal-pelvic MDCT? A phantom and patient study

OBJECTIVE: Our objective was to assess the effect of orthopedic metallic prostheses on radiation dose associated with MDCT using z-axis automatic tube-current modulation and a fixed tube current in a phantom and patient study. CONCLUSION: Z-modulation is associated with a 34.1% increase in the mean tube current-time product and no change in the extent of streak artifacts in patients with a metallic prosthesis, compared with patients without a prosthesis. However, compared with the fixed-tube-current technique, z-modulation is associated with a 28.9% decrease in the mean tube current-time product.     

"Anode heel effect" on patient dose in lumbar spine radiography

Appropriate use of the "anode heel effect" of the output beam from an X-ray tube can reduce the effective dose to patients in some common radiological examinations. We investigated the variation in radiation intensity across the X-ray beam caused by the anode heel effect, and quantified the difference in absorbed dose to critical organs resulting from lumbar spine X-ray projections carried out with the two possible orientations of the patient along the tube axis (cathode to anode). A Rando phantom and some high sensitivity thermoluminescent dosemeters (TLDs) (LiF:Mg,Cu,P) were used. With the tube axis horizontal, radiation intensity profiles, parallel and perpendicular to the axis, were measured. Lumbar spine radiographs were recorded using the Rando phantom in the standard anteroposterior (AP) and lateral projections. TLD pellets were used to measure the absorbed radiation dose at various sites corresponding to critical organ tissues (ovaries, testes, breasts, thyroid and lens). Each set of projections was recorded in two phantom orientations, first with the phantom head placed towards the cathode end of the X-ray tube, and then in the reverse direction. From the radiation intensity profile of the incident X-ray beam, the "cathode end" to "anode end" air dose ratio was found to be 1.8. In lumbar spine radiography, with the phantom head placed towards the anode end of the X-ray tube, the ovaries and testes received an average dose 17% and 12% higher, respectively, in the lateral projection, and 16% and 27% higher, respectively, in the AP projection, than those obtained in the reverse "patient" orientation. These results indicate that patients (particularly females) should always be positioned with the head placed towards the cathode end of the X-ray tube for lumbar spine radiography to achieve significant dose reductions.