Fluoroscopy: An essential diagnostic modality in the age of high-resolution cross-sectional imaging

The importance of fluoroscopy as an imaging modality has been minimized relative to other cross-sectional modalities, including high-resolution computed tomography (CT), magnetic resonance imaging (MRI) and ultrasound. Fluoroscopy examinations have decreased in clinical practice due to reduced appreciation of its usefulness, insufficient training of residents, fewer staff with adequate expertise, and poor reimbursements relative to other modalities. We revisit and build upon the prior literature and history of this decreased utilization. We then seek to prove continued value, through categorized examples and within multiple subspecialties, wherein fluoroscopy plays an integral part toward clinical diagnoses as well as optimizing patient outcomes. This is particularly true for motility and esophageal disorders, where structure and function with real-time evaluation is essential.  We additionally show several post-operative cases where the synergy of fluoroscopy with CT and endoscopy is apparent.  The fluoroscopic radiologist also has the unique ability to vary patient positioning, as opposed to traditional CT or MRI, where orthogonal views are employed without positional or temporal changes. We turn attention to the modern era, with synergistic and novel cases demonstrating that fluoroscopy remains instrumental toward achieving a diagnosis alongside other modalities. Our cases stress the need to maintain expertise in fluoroscopy skill, and underline its continued importance in residency training programs.  We conclude that fluoroscopy is a relatively inexpensive modality that is often under-appreciated in diagnostic radiology. We suggest that competency in fluoroscopy is crucial for future generations of radiologists to both work with their peers, as well as to aid clinicians in the optimal treatment of patients.     

AERMOD在核设施辐射环境影响评价中的应用研究

目的 基于AERMOD模型机理，研究其在核设施辐射环境影响评价中的应用。方法 根据给定的释放源项和厂址气象数据，模拟获取核设施常规运行时气态放射性核素浓度分布，并进一步定性分析气态流出物浓度峰值落地点和时间分布，研究AERMOD模型在核设施辐射环境影响评价中的适用性和应用前景。结果 通过AERMOD模型适用性和应用前景分析，得出该模型总体满足核设施气态流出物浓度分布计算需求，可应用于核设施气态流出物扩散趋势和敏感点分析，并可为核设施常规运行的监测计划提供数据支撑。结论 本研究可为今后深入开展AERMOD模型在核设施辐射环境影响评价中的应用提供参考。     

基于品质因素评价瓦里安锥束CT成像质量与辐射剂量风险收益比

目的 分析比对不同Varian加速器平台机载千伏锥束CT（kV CBCT）系统的辐射剂量和成像质量，指导临床选用风险收益比（成像质量/辐射剂量）最高的图像引导方案。方法 利用CT剂量指数模体（CTDI模体）和CT电离室，以及Catphan604模体分别获取Edge、Truebeam、新旧两台ix加速器机载CBCT典型扫描模式的辐射剂量和成像质量参数，使用品质因素（figure of merit，FOM）值评估各图像引导方案的风险收益比。结果 不同型号的瓦里安加速器配置的kV CBCT系统的FOM不同，差异广泛分布于0.65（温和成像一圈）~48.46（温和成像半圈）区间；各扫描参数间FOM也存在较大差异，均值为22.14±13.47。结论 由于设备间和参数间存在显著差异，基于实际测量的验证评估有助于临床选择合理的影像引导方案，剂量敏感患者应优先选择加权CT剂量指数（CTDI_w）低的参数和设备；对图像质量要求高的患者应优选对比度噪声比（CNR）高的方案；而普通患者则可依据风险收益比进行选择，此时品质因素FOM可为临床决策提供有利工具。     

Inhibition of PRRX2 suppressed colon cancer liver metastasis via inactivation of Wnt/β-catenin signaling pathway

The aim of this study was to investigate whether PRRX2 may regulate the liver metastasis of colon cancer via the Wnt/β-catenin signaling pathway. PRRX2 and β-catenin in patients with the liver metastases of colon cancer was detected by immunochemistry. Colon cancer cells (CT-26 and CMT93) were divided into Normal, si-Ctrl, si-PRRX2 and si-PRRX2 +LiCl groups. Cell invasive and migrating abilities and the related proteins were detected. Liver-metastatic mice model was constructed consisting of Normal, NC shRNA and PRRX2 shRNA groups to examine the function of PRRX2 shRNA on liver metastasis. We found that PRRX2 and β-catenin positive rate was elevated in colon cancer tissues, especially in those tissues with liver metastasis, and there was a close relation between PRRX2 and the clinical staging, lymph node metastasis and numbers of liver metastases of colon cancer patients with liver metastasis. In vitro, the invasive and migrating abilities of CT-26 and CMT93 cells decreased apparently in the si-PRRX2 group, with down-regulation of PRRX2, p-GSK3β^Ser9/GSK3β, nucleus and cytoplasm β-catenin, TCF4 and Vimentin but up-regulation of E-cadherin. However, LiCl, the Wnt/β-catenin pathway activator, can reverse the inhibitory effect of si-PRRX2 on invasive and migrating ability of colon cancer cells. In vivo, the volume and weight of transplanted tumor and the number of liver metastases in the PRRX2 shRNA group were significantly reduced, with the similar protein expression patterns as in vitro. In a word, PRRX2 inhibition may reduce invasive and migrating abilities to hinder epithelial-mesenchymal transition (EMT), and suppress colon cancer liver metastasis through inactivation of Wnt/β-catenin pathway.     

An Environmental Scan of the National and Provincial Diagnostic Reference Levels in Canada for Common Adult Computed Tomography Scans

Several regulatory bodies have agreed that low-dose radiation used in medical imaging is a weak carcinogen that follows a linear, non-threshold model of cancer risk. While avoiding radiation is the best course of action to mitigate risk, computed tomography (CT) scans are often critical for diagnosis. In addition to the as low as reasonably achievable principle, a more concrete method of dose reduction for common CT imaging exams is the use of a diagnostic reference level (DRL). This paper examines Canada's national DRL values from the recent CT survey and compares it to published provincial DRLs as well as the DRLs in the United Kingdom and the United States of America for the 3 most common CT exams: head, chest, and abdomen/pelvis. Canada compares well on the international scale, but it should consider using more electronic dose monitoring solutions to create a culture of dose optimization.     

Risk analysis for radiotherapy at the Universitätsklinikum Erlangen

PurposeRisk analysis is required by various laws and regulations in Germany and has an impact on each department of a large clinic. We provide an overview of the relevant laws and regulations in Germany and present the technical and organizational experience of introducing risk analysis in the Department of Radiation Oncology at the Universitätsklinikum Erlangen.MethodsRisk analysis was performed with an in-house developed extension of our intranet platform and ticketing system. Risks were classified according to occurrence and severity, each on a 5-level scale resulting into a risk matrix. An interdisciplinary team of six experienced members formed the core meeting weekly.ResultsA total of 38 risks and 50 measures have been identified in 41 1 h-meetings corresponding to approx. 260 working hours. Risk was distributed 8/20/13 to the categories critical (n = 8), monitoring (n = 20), and conditionally acceptable (n = 13). Risk analysis has been evaluated before and after introducing measures.ConclusionThe risk analysis method introduced has been successfully used in routine operations for over a year. Risk analysis takes time and effort. However, because experts from different disciplines meet each other every week, the overall workflow of the radiation oncology department can be improved efficiently and continuously.     

Ultra-low-dose unenhanced chest CT: Prospective comparison of high kV/low mA versus low kV/high mA protocols

Purpose

To qualitatively and quantitatively compare unenhanced ultra-low-dose chest computed tomography (ULD-CT) acquired at 80 kVp and 135 kVp.

ITV-Based Robust Optimization for VMAT Planning of Stereotactic Body Radiation Therapy of Lung Cancer

Purpose

Using planning target volume (PTV) to account for setup uncertainties in stereotactic body radiation therapy (SBRT) of lung cancer has been questioned because a significant portion of the PTV contains low-density lung tissue. The purpose of this study is to (1) investigate the feasibility of using robust optimization to account for setup uncertainties in volumetric modulated arc therapy plan for lung SBRT and (2) evaluate the potential normal tissue–sparing benefit of a robust optimized plan compared with a conventional PTV-based optimized plan.