Manual or auto-mode: Does this affect radiation dose in digital mammography without compromising image quality?

IntroductionIn current practice, auto-filter exposure mode is used for most screening mammography examinations. However, with better understanding of the side effects of radiation, it is important to examine exposure parameters and practises to minimise radiation dose to patients. The purpose of this phantom study is to investigate the impact that different exposure modes (manual, auto-time and auto-filter) have on radiation dose, while maintaining images of diagnostic quality.MethodsThis study was conducted in three stages. In the first stage, 125 images were taken using a Gammex 156 phantom with polymethyl methacrylate blocks to reflect varying thicknesses (4.5, 5.0, 5.5, 6.0 and 6.5 cm). In the second stage, three mammographers independently assessed image quality and assigned scores based on the number of distinct fibers, masses and speck groups visible. Images with acceptable quality were further investigated in the third stage by comparing their average glandular dose (AGD) using the Kruskal–Wallis H test and Dunn's post-hoc pairwise analysis.ResultsSignificant differences in AGD were shown between the auto-filter mode and manual mode techniques for 6.0 cm, and between auto-time mode and manual mode techniques for 6.5 cm (p < 0.05).ConclusionFor 4.5, 5.0 and 5.5 cm phantoms, as AGD was not significantly different among the different modes, the auto-filter may remain the most practical option. However, significant reductions in AGD were obtained for the 6.0 and 6.5 cm phantoms when manual mode techniques were used.Implications for practiceManual mode techniques can potentially provide dose-saving opportunity in 6.0 and 6.5 cm breast thickness though future work on human breast should be done to confirm this. Results from this study will support future research based on patient data.     

基于基因表达综合数据库筛选调控急性T淋巴细胞白血病超高剂量率放疗敏感性的枢纽基因

目的 通过生物信息学方法对基因表达综合(GEO)数据库中超高剂量率(FLASH)放疗的数据进行分析,寻找参与调控急性T淋巴细胞白血病FLASH放疗敏感性的枢纽(Hub)基因。方法 从GEO数据库中下载和提取接受FLASH放疗恶性肿瘤基因表达谱芯片数据,采用R软件进行差异基因的筛选,并对这些基因进行生物学功能、信号传导通路等分析。通过STRING在线软件分析差异基因的蛋白质相互作用(PPI) 网络,Cytoscape插件筛选Hub基因。最后,应用肿瘤基因组图谱(TCGA)和GTEx数据库验证Hub基因在急性T淋巴细胞白血病中的表达情况。结果 自GEO数据库中获得GSE100718芯片数据,共有12 800个基因与急性T淋巴细胞白血病放疗敏感性相关。选择表达量显著改变的61个基因进行进一步分析,这些基因参与代谢、应激反应、免疫应答等生物学过程。主要涉及氧化磷酸化、未折叠蛋白应答、脂质代谢等信号转导通路。通过PPI分析筛选出的Hub基因及后续验证表明HSPA5及SCD参与调控FLASH放疗敏感性,且在合并TRD/LMO2融合基因的急性T淋巴细胞白血病中显著高表达。结论 通过生物信息学分析可以有效筛选出调控FLASH放疗敏感性的Hub基因,基因表达谱可用于指导肿瘤患者分层以实现精准放疗。     

Collar Badge Lens Dose Equivalent Values among United States Physicians Performing Fluoroscopically Guided Interventional Procedures

PurposeTo describe the range of occupational badge dose readings and annualized dose records among physicians performing fluoroscopically guided interventional (FGI) procedures using job title information provided by the same 3 major medical institutions in 2009, 2012, and 2015.Materials and MethodsThe Radiation Safety Office of selected hospitals was contacted to request assistance with identifying physicians in a large commercial dosimetry database. All entries judged to be uninformative of occupational doses to FGI procedure staff were excluded. Monthly and annualized doses were described with univariate statistics and box-and-whisker plots.ResultsThe dosimetry data set of interventional radiology staff contained 169 annual dose records from 77 different physicians and 698 annual dose records from 455 nonphysicians. The median annualized lens dose equivalent values among physicians (11.9 mSv; interquartile range [IQR], 6.9–20.0 mSv) was nearly 3-fold higher than those among nonphysician medical staff assisting with FGI procedures (4.0 mSv; IQR, 1.8–6.7 mSv) (P < .001). During the study period, without eye protection, 25% (23 of 93) of the physician annualized lens dose equivalent values may have exceeded 20 mSv; for nonphysician medical staff, this value may have been exceeded 3.5% (6 of 173) of the time. However, these values did not account for eye protection.ConclusionsThe findings from this study highlight the importance of mitigating occupational dose to the eyes of medical staff, particularly physicians, performing or assisting with FGI procedures. Training on radiation protection principles, the use of personal protective equipment, and patient radiation dose management can all help ensure that the occupational radiation dose is adequately controlled.     

Dose-dense chemotherapy for breast cancer

The concept of dose-dense chemotherapy has emerged and is based on the hypothesis that maximal chemotherapy effectiveness can be achieved by scheduling the interval of chemotherapy to correspond to the period of most rapid tumor growth, as predicted by preclinical models. The granulocyte-colony stimulating factor support has permitted the safe delivery of chemotherapy at shorter ("dose-dense") inter-treatment intervals. Several randomized trials have been conducted to test the feasibility and effectiveness of anthracycline and/or taxanes-based dose-dense strategies. They have been associated with a modest impact on disease recurrence and overall survival of patients with early-stage breast cancer. Subset analyses have suggested increased benefits for specific tumor subtypes such as hormone receptor-negative, highly proliferative or HER2 overexpressing tumors. This review article aims to outline the theoretical framework for dose-dense chemotherapy and summarizes the results of several recent clinical trials addressing this concept within neoadjuvant and adjuvant breast cancer treatment and discuss their implications for clinical practice. Further studies are needed to define the optimal regimen and the patient population that will receive the greatest benefit from dose-dense strategy.     

Radiation exposure to premature infants in a neonatal intensive care unit in Turkey

OBJECTIVE: The aim of this work was to determine the radiation dose received by infants from radiographic exposure and the contribution from scatter radiation due to radiographic exposure of other infants in the same room. MATERIALS AND METHODS: We retrospectively evaluated the entrance skin doses (ESDs) and effective doses of 23 infants with a gestational age as low as 28 weeks. ESDs were determined from tube output measurements (ESD(TO)) (n = 23) and from the use of thermoluminescent dosimetry (ESD(TLD)) (n = 16). Scattered radiation was evaluated using a 5 cm Perspex phantom. Effective doses were estimated from ESD(TO) by Monte Carlo computed software and radiation risks were estimated from the effective dose. ESD(TO) and ESD(TLD) were correlated using linear regression analysis. RESULTS: The mean ESD(TO) for the chest and abdomen were 67 microGy and 65 microGy per procedure, respectively. The mean ESD(TLD) per radiograph was 70 microGy. The measured scattered radiation range at a 2 m distance from the neonatal intensive care unit (NICU) was (11-17 microGy) per radiograph. Mean effective doses were 16 and 27 microSv per procedure for the chest and abdomen, respectively. ESD(TLD) was well correlated with ESD(TO) obtained from the total chest and abdomen radiographs for each infant (R(2) = 0.86). The radiation risks for childhood cancer estimated from the effective dose were 0.4 x 10(-6) to 2 x 10(-6) and 0.6 x 10(-6) to 2.9 x 10(-6) for chest and abdomen radiographs, respectively. CONCLUSION: The results of our study show that neonates received acceptable doses from common radiological examinations. Although the contribution of scatter radiation to the neonatal dose is low, considering the sensitivity of the neonates to radiation, further protective action was performed by increasing the distance of the infants from each other.     

64排螺旋CT冠状动脉成像的前瞻性与回顾性心电门控技术的图像质量及辐射剂量的比较研究

目的 研究前瞻性心电门控触发(prospective ECG-triggering)与回顾性心电门控(retrosp-ective ECG gating)两种技术方法行冠状动脉CTA检查时,对冠状动脉图像质量及辐射剂量的比较.方法 33名疑似冠状动脉疾病的患者分两组进行对比研究.前瞻组16例为前瞻性心电门控成像,心率小于65次/min;回顾组17例为回顾性心电门控成像,心率小于75次/min.记录两组的辐射剂量并统计分析,同时进行图像质量评价.结果 两组图像质量比较,差异无统计学意义(P0.05).前瞻性心电门控冠状动脉CTA的平均DLP 234.4 mGy·cm,占回顾性心电门控冠状动脉CTA的平均DLP 974.4 mGy·cm的24.1%.前瞻性心电门控冠状动脉CTA的患者的平均有效剂量为3.2 mSy,回顾心电门控冠状动脉CTA患者的为13.6 mSv,降低76.47%.结论 64排螺旋CT在前瞻性心电门控冠状动脉CTA与回顾性心电门控冠状动脉CTA比较可以获得相似的图像质量,可大幅降低患者的有效剂量对于不能接受高辐射剂量且心率较低的受检人群具有重要的临床价值.     

Lowering radiation dose for integrated assessment of coronary morphology and physiology: First experience with step-and-shoot CT angiography in a rubidium 82 PET-CT protocol

Background. Reduction of radiation exposure from computed tomography coronary angiography (CTA) will be a key factor for more liberal use in cardiac hybrid positron emission tomography (PET)-computed tomography (CT). We report our initial experience with a new algorithm for low-dose CTA based on a prospectively gated step-and-shoot technique. This limits acquisition to the diastolic phase and minimizes exposure time versus the previous standard of retrospectively gated helical acquisitions. Methods and Results. In 15 consecutive patients referred for integrated functional and morphologic workup by rubidium 82 perfusion PET-CTA, step-and-shoot CTA (SnapShot Pulse; GE Medical Systems) (120 kV, 600–800 mA) was acquired on a 64-slice GE Discovery Rx VCT PET-CT scanner and compared with a group of patients with conventional helical CTA (120 kV, with modulation of the milliampere level) who were matched with regard to clinical variables. Effective dose was estimated from dose-length product. The American Heart Association 15-segment coronary tree model was used to determine study interpretability. Potential for fusion with Rb-82 perfusion PET was tested by use of commercial software. In addition, direct dose measurements were conducted by use of an anthropomorphic phantom for more accurate dosimetry. The dose-length product-derived effective patient dose for step-and-shoot and helical CTA was 5.5±0.1 mSv versus 20.5±3.5 mSv (P<.0001). The mean number of evaluable segments per patient for the best phase of helical CTA was 12.5±2.8 (83.3%±18.7%) versus 13.3±2.2 (88.7%±14.7%) (P=not significant vs helical) for step-and-shoot CTA. Review of multiple phases increased the number for helical CTA to 13.7±1.7 (91.3%±11.3%;P=not significant vs step-and-shoot CTA, for which this was not an option). Semiautomated fusion with corresponding PET was feasible for all studies. Phantom data confirm effective doses of 5.4 mSv for step-and-shoot CTA and 19.6 mSv for helical acquisition. Conclusions. Low-dose prospectively gated CTA reduces radiation exposure by nearly 70% versus the previous standard of helical acquisition, without significant loss in interpretability and integrative potential with Rb-82 perfusion PET. This represents a step toward a broader, routine integration of CTA and perfusion PET for assessment of coronary morphology and physiology by cardiac PET-CT.     

低剂量半身照射对恶性肿瘤患者免疫功能的影响

目的 评价低剂量辐射对恶性肿瘤患者免疫功能的影响。方法 将20例患者(其中非何杰金氏淋巴瘤13例、小细胞肺癌7例)随机分为两组:HBR组和RR组。其中HBR组10例患者采用常规放疗(RR)加低剂量半身照射,低剂量半身照射方法为10 cGy/次,2次/周,总剂量为100 cGy,每次均间隔6～8 h再行常规放疗;RR组10例患者只予以常规放疗。采用流式细胞术(FCM)双标法检测HBR与RR组在放疗前、中、后外周血淋巴细胞CD₄、CD₈、CD₂₅和CD₅₆等指标的变化。结果 照射后RR组患者的CD₄⁺ CD₈⁺降低(P<0.05),HBR组患者的CD₄⁺升高(P<0.05),CD₂₅⁺和CD₅₆⁺分子表达均明显地增加(P<0.05),放疗前和放疗后CD₈⁺均低(P<0.05),放疗中(P<0.05)和放疗后(P<0.01)CD₄⁺ CD₈⁺均高。结论 低剂量半身照射可增强机体的免疫功能。     

低剂量辐射增强小鼠肿瘤基因-放射治疗效应的免疫学机制研究

目的 探讨低剂量辐射全身照射对小鼠Lewis肺癌移植肿瘤基因-放疗方案中的免疫增强作用机制。方法 小鼠右后肢皮下接种Lewis肺癌细胞建立荷瘤模型,基因-放疗组中小鼠肿瘤局部注射由多聚乙烯亚胺包裹的pEgr-IL18-B7.1重组质粒,分别接受由2 Gy 局部照射和0.075 Gy 全身照射组合的不同治疗方案,通过³H-TdR标记方法检测小鼠CTL和NK细胞毒活性,ELISA方法检测TNF-α和IFN-γ分泌活性,观察各治疗组对荷瘤小鼠抗肿瘤免疫的作用。结果 在pEgr-IL18-B7.1基因治疗方案中,单次大剂量辐射局部照射后加多次低剂量全身照射与常规多次大剂量辐射局部照射相比,小鼠CTL和NK细胞毒活性显著增强,TNF-α和IFN-γ分泌活性有不同程度的增高。 结论 低剂量辐射可以通过促进CTL和NK细胞毒效应,上调TNF-α和IFN-γ细胞因子表达,从而增强机体抗肿瘤免疫功能,提高肿瘤基因-放疗的抑瘤效果。