bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transcatheter chemoembolization for unresectable hepatocellular carcinoma and comparison of five staging systems
Authors: Kawaoka Tomokazu , Aikata Hiroshi , Takaki Shintaro , Hashimoto Yoshimasa , Katamura Yoshio , Hiramatsu Akira , Waki Koji , Takahashi Shoichi , Kamada Koji , Kitamoto Mikiya , Nakanishi Toshio , Ishikawa Masaki , Hieda Masashi , Kakizawa Hideaki , Tanaka Junko , Chayama Kazuaki 
Published: September 2010

Aim:  We compared the ability of five staging system to predict survival in patients with hepatocellular carcinoma (HCC) treated with chemoembolization.Methods:  The study subjects were 214 patients with HCC treated with repeated chemoembolization alone using cisplatin and lipiodol. Predictors of survival were assessed by multivariate analysis. Before chemoembolization was carried out, the modified Japan Integrated Staging (m‐JIS), Japan Integrated Staging (JIS score), Barcelona (BCLC) stage, Liver Cancer Study Group of Japan/Tumor–Node–Metastasis (LCSGJ/TNM) and Italian score (CLIP score) were checked. To validate the prognostic value of these staging systems, the survival curve was obtained and analyzed by the Kaplan–Meier method. Discriminatory ability and predictive power were compared using Akaike's information criterion (AIC) score and the likelihood ratio (LR) χ2.Results:  Overall survival was 1 year in 82.9%, 3 years in 39.9% and 5 years in 15.1%. Multivariate analysis identified more than 90% lipiodol accumulation (grade I) after the first chemoembolization (P = 0.001), absence of portal vein tumor thrombosis (PVTT) (P < 0.001) and liver damage A (P = 0.012) as independent determinants of survival. AIC score and the LR χ2 showed superior predictive power of the m‐JIS system in 95 patients with grade I accumulation of lipiodol after first chemoembolization.Conclusion:  The discriminate ability of the m‐JIS score is substantially better than those of other staging systems and has better prognostic predictive power in patients with grade I accumulation of lipiodol after first chemoembolization.
Politically‐Connected Boards and the Structure of Chief Executive Officer Compensation Packages in Taiwanese Firms*
Authors: Yu Hsin‐Yi 
Published: September 2010

AbstractThis paper examines the relationship between the level of political connection of the board and chief executive officer (CEO) equity‐based compensation. Using a sample of Taiwanese firms, the paper provides evidence that politically connected boards grant a lower proportion of equity‐based compensation to CEOs. Political intervention can reduce the proportion of equity‐based compensation and, thereby, can have negative consequences for the alignment between the interests of CEOs and shareholders in firms. The findings obtained in this paper could be useful to policy‐makers in emerging economies, where there is wide scope for political intervention.
Liquidity Commonality and its Causes: Evidence from the Korean Stock Market*
Authors: Choe Hyuk , Yang Cheol‐Won 
Published: September 2010

AbstractThis paper investigates the causes of liquidity commonality. We consider information asymmetry, volatility, utilitarian trading interest, style‐based trading, inventory cost, and investor sentiment as potential candidates. Our empirical analysis shows that greater information asymmetry causes higher liquidity commonality. The significant effect of the order imbalance beta supports our volatility hypothesis as a cause of liquidity commonality. Program trading and the KOSPI200 index dummy are positively related to liquidity commonality, which is consistent with the style‐based trading hypothesis. Higher individual trading is associated with higher liquidity commonality, which means that investor sentiment operates in the Korean market. However, volume beta and return beta, as proxies for the utilitarian trading effect and the inventory cost, respectively, are insignificantly related to liquidity commonality.
Hedge Ratio Stability and Hedging Effectiveness of Time‐Varying Hedge Ratios in Volatile Index Futures Markets: Evidence from the Asian Financial Crisis*
Authors: Wang Janchung , Hsu Hsinan 
Published: September 2010

AbstractHedge ratio stability is especially important because hedgers are likely to use the estimate of historical hedge ratios to hedge future positions of their portfolios. One main purpose of the present study is to examine hedge ratio stability during the Asian financial crisis and post‐crisis, periods characterized by high price volatility, using the Nikkei 225, Hang Seng, and KOSPI 200 index futures contracts. Empirical results from the Hang Seng and the KOSPI 200 futures markets indicate that during the two periods of high price volatility, hedge ratios appeared to be unstable. Additionally, both in‐sample and out‐of‐sample evidences indicate that, for hedging effectiveness, the time‐varying hedge ratios clearly outperform the constant hedge ratios for the Hang Seng and the KOSPI 200 index futures, consistent with the findings of hedge ratio instability. The comparison results of different time‐varying hedge ratios support the conclusion that the bivariate error correction generalized autoregressive conditional heteroskedastic (1,1) model enhances hedging effectiveness compared to other time‐varying hedge ratios. Finally, this study examines the impact of hedge duration on hedging effectiveness and hedge ratios. The empirical results indicate that hedging effectiveness improves with increasing hedge duration.
Idiopathic aseptic pericardial effusion with cardiac tamponade in a horse
Authors: Malalana F. , Bardell D. , McKane S. 
Published: September 2010

SummaryThis report describes the successful treatment of pericardial effusion and cardiac tamponade in a 10‐year‐old Hanoverian gelding. Pericarditis and pericardial effusion are uncommon conditions in horses. Although many potential causes for the effusion have been described most cases are classified as idiopathic. The most valuable diagnostic procedure for the detection of pericardial effusion is echocardiography. Pericardiocentesis and drainage of the fluid were carried out in this case. At one year follow‐up there were no clinical signs of recurrence and the horse has returned to his previous level of athletic performance.
Evaluation of spherical fiducial localization in C‐arm cone‐beam CT using patient data
Authors: Yaniv Ziv 
Published: September 2010

Purpose:C‐arm based cone‐beam CT (CBCT) has been recently introduced as anin‐situ 3D soft tissue imaging modality. When combined with image‐guided navigation, it provides a streamlined clinical workflow with, potentially, improved interventional accuracy. A key component in these systems is image to patient registration. The most common registration method relies on fiducial markers placed on the patient's skin. The fiducials are localized in the volumetric image and in the interventional environment. When using C‐arm CBCT, the small spatial extent of the volumetric reconstruction makes this registration approach challenging, as the volume must include both the anatomy of interest and the fiducials. The authors have previously proposed a semiautomatic localization approach that addresses this challenge, with evaluation carried out using anthropomorphic phantoms. To truly evaluate the algorithm's utility, the evaluation must be carried out using clinical data. In this article, the authors extend the evaluation of the approach to data sets acquired in a clinical trial.Methods:Nine CBCT data sets were obtained in three interventional radiology procedures as part of a clinical trial evaluating a commercial navigation system. Fiducials were localized in the volumetric coordinate system directly from the projection images using the evaluated localization approach. Localization was assessed using two quality measures fiducial registration error to quantify precision and fiducial localization error to quantify accuracy. The fiducials used in this study are 6 mm spheres embedded in a custom registration phantom used by the navigation system.Results:In all cases, the proposed approach was able to localize all five fiducial markers embedded in the registration phantom. The approach's mean (std) fiducial registration error was 0.29 (0.13) mm. The mean (std) localization difference as compared to direct volumetric localization was 0.82 (0.34) mm.Conclusions:Based on the current evaluation using data from clinical cases, the authors conclude that the localization approach is sufficiently accurate for use in thoracic‐abdominal interventions, and that it can simplify the current workflow while reducing cumulative radiation to the patient due to repeated CBCT scans.
A support vector machine (SVM) for predicting preferred treatment position in radiotherapy of patients with breast cancer
Authors: Zhao Xuan , Wong Edward K. , Wang Yao , Lymberis Stella , Wen Bixiu , Formenti Silvia , Chang Jenghwa 
Published: September 2010

Purpose:NYU 05‐181 protocol compared the CT simulation in both supine and prone positions for 400 patients with breast cancer (200 left‐breast and 200 right‐breast) to identify which setup is better at sparing heart and lung involvement in the treatment process. The results demonstrated that all right‐breast patients benefited from the prone treatment position, while for left‐breast patients, 85% were better treated prone and 15% were better treated supine. Using the clinical data collected from this protocol, the authors aimed at developing an automated tool capable of identifying which of the left‐breast cancer patients are better treated supine without obtaining a second CT scan in the supine position.Methods:Prone CT scans from 198 of the 200 left‐breast cancer patients enrolled in NYU 05‐181 protocol were deidentified and exported to a dedicated research planning workstation. Three‐dimensional geometric features of the organs at risk and tumor bed were extracted. A two‐stage classifier was used to classify patients into the prone class or the supine class. In the first stage, the authors use simple thresholding to divide the patients into two groups based on their in‐field heart volume. For patients with in‐field heart volume, the prone position was chosen as the preferred treatment position. Patients with in‐field heart volume will be further classified in the second stage by a weighted support vector machine (SVM). The weight parameters of the SVM were adjusted to maximize the specificity at the cost of lowering but still maintaining reasonable sensitivity . The authors used ‐fold cross validations to test the performance of the SVM classifier. A feature selection algorithm was also used to identify features that give the best classification performance.Results:After the first stage, 49 of the 198 left‐breast cancer patients were found to have of in‐field heart volume. The three geometric features of heart orientation, distance between heart and tumor, and in‐field lung were selected by the feature selection algorithm in the second stage of the two‐stage classifier to give the best predefined weighted accuracy. The overall sensitivity and specificity of the proposed method were found to be 90.4% and 99.3%, respectively. Using two‐stage classification, the authors reduced the proportion of prone‐treated patients that need a second supine CT scan down to 16.3/170 or 9.6%, as compared to 21/170 or 12.4% when the authors use only the first stage (thresholding) for classification.Conclusions:The authors’ study showed that a feature‐based classifier is feasible for predicting the preferred treatment position, based on features extracted from prone CT scans. The two‐stage classifier achieved very high specificity at an acceptable expense of sensitivity.
Noninvasive mapping of spontaneous fluctuations in tumor oxygenation using MRI
Authors: Magat J. , Jordan B. F. , Cron G. O. , Gallez B. 
Published: September 2010

Purpose:Acute hypoxia (transient cycles of hypoxia‐reoxygenation) is known to occur in solid tumors and may be a poorly appreciated therapeutic problem as it can be associated with resistance to radiation therapy, impaired delivery of chemotherapeutic agents, or metastasis development. The objective of the present study was to use MR relaxometry maps to analyze the spontaneous fluctuations of partial pressure of oxygen over time in experimental tumors.Methods:The maps were generated after direct intratumoral administration of a fluorine compound (hexafluorobenzene) whose relaxation rate is proportional to the % . The authors used a SNAP inversion‐recovery sequence at 4.7 T to acquire parametric images of the relaxation time with a high spatial and temporal resolution. Homemade routines were developed to perform regions of interest analysis, as well as pixel by pixel analysis of over time.Results:The authors were able to quantify and probe the heterogeneity of spontaneous fluctuations in tumor: (i) Spontaneous fluctuations in occurred regardless of the basal oxygenation state (i.e., both in oxygenated and in hypoxic regions) and (ii) spontaneous fluctuations occurred at a rate of 1 cycle/12–47 min. For validation, the analysis was performed in dead mice for which acute changes did not occur. The authors thereby demonstrated that MRI technique is sensitive to acute change in in tumors.Conclusions:This is the first approach that allows quantitative minimally invasive measurement of the spontaneous fluctuations of tumor oxygenation using a look‐locker approach (e.g., SNAP IR). This approach could be an important tool to characterize the phenomenon of tumor acute hypoxia, to understand its physiopathology, and to improve therapies.
Clinical development of a failure detection‐based online repositioning strategy for prostate IMRT—Experiments, simulation, and dosimetry study
Authors: Liu Wu , Qian Jianguo , Hancock Steven L. , Xing Lei , Luxton Gary 
Published: September 2010

Purpose:To implement and evaluate clinic‐ready adaptive imaging protocols for online patient repositioning (motion tracking) during prostate IMRT using treatment beam imaging supplemented by minimal, as‐needed use of on‐board kV.Methods:The authors examine the two‐step decision‐making strategy: (1) Use cine‐MV imaging and online‐updated characterization of prostate motion to detect target motion that is potentially beyond a predefined threshold and (2) use paired MV‐kV 3D localization to determine overthreshold displacement and, if needed, reposition the patient. Two levels of clinical implementation were evaluated: (1) Field‐by‐field based motion correction for present‐day linacs and (2) instantaneous repositioning for new‐generation linacs with capabilities of simultaneous MV‐kV imaging and remote automatic couch control during treatment delivery. Experiments were performed on a Varian Trilogy linac in clinical mode using a 4D motion phantom programed with prostate motion trajectories taken from patient data. Dosimetric impact was examined using a 2D ion chamber array. Simulations were done for 536 trajectories from 17 patients.Results:Despite the loss of marker detection efficiency caused by the MLC leaves sometimes obscuring the field at the marker's projected position on the MV imager, the field‐by‐field correction halved (from 23% to 10%) the mean percentage of time that target displacement exceeded a 3 mm threshold, as compared to no intervention. This was achieved at minimal cost in additional imaging (average of one MV‐kV pair per two to three treatment fractions) and with a very small number of repositionings (once every four to five fractions). Also with low kV usage , the instantaneous repositioning approach reduced overthreshold time by more than 75% (23% to 5%) even with severe MLC blockage as often encountered in current IMRT and could reduce the overthreshold time tenfold (to ) if the MLC blockage problem were relieved. The information acquired for repositioning using combined MV‐kV images was found to have submillimeter accuracy.Conclusions:This work demonstrated with a current clinical setup that substantial reduction of adverse targeting effects of intrafraction prostate motion can be realized. The proposed adaptive imaging strategy incurs minimal imaging dose to the patient as compared to other stereoscopic imaging techniques.
Validation for photon beams in the energy range of 20–1000 keV
Authors: Terribilini Dario , Fix Michael K. , Frei Daniel , Volken Werner , Manser Peter 
Published: September 2010

Purpose:In high energy teletherapy,is known to be a very accurate and efficient Monte Carlo (MC) code. In principle, the MC method is also a powerful dose calculation tool in other areas in radiation oncology, e.g., brachytherapy or orthovoltage radiotherapy. However,is not validated for the low‐energy range of such applications. This work aims in the validation of theMC code for photon beams in the energy range between 20 and 1000 keV.Methods:Dose calculations were performed in differentphantoms of different materials. Dose distributions of monoenergetic (ranging from 20 to 1000 keV)andparallel beams were calculated. Voxel sizes ofandwere used for the dose calculations. The resulting dose distributions were compared to those calculated using EGSnrc, which is used as a golden standard in this work.Results:At energies between 100 and 1000 keV, EGSnrc andcalculated dose distributions agree within the statistical uncertainty of about 1%. At energies, dose differences of up to 1.6% (in % of) occur whenand EGSnrc are compared. Turning off Rayleigh scattering, binding effects for Compton scattering, and the atomic relaxation after photoelectric absorption in EGSnrc (all not implemented in) leads to an agreement between both MC codes within statistical uncertainty. Further, using the KERMA approximation feature implemented inleads to very efficient simulations in the energy range between 20 and 1000 keV.Conclusions:Further improvements for very low energies in accuracy ofcould be achieved by implementing Rayleigh scattering, binding effects for Compton scattering, and the atomic relaxation after photoelectric absorption. Implementation intoof KERMA approximation has been validated.
Regularized antenna profile adaptation in online hyperthermia treatment
Authors: Ranneberg Maximilian , Weiser Martin , Weihrauch Mirko , Budach Volker , Gellermann Johanna , Wust Peter 
Published: September 2010

Purpose:Online optimization of annular‐phased‐array hyperthermia (HT) is based on planning tools and magnetic resonance (MR) thermometry. Until now, the method has been validated in phantoms. Further developments and extensions are required for clinical purposes. In particular, the problem of deducing the electric field distribution inside the patient from MR thermometry is ill‐posed, which leads to an amplification of measurement errors. A method to overcome this difficulty is proposed.Methods:The authors utilized a regularized Gauß–Newton algorithm with a fast bioheat transfer equation (BHTE) approximation to identify the field parameters. To evaluate the method, simulations with patient models are conducted and a treatment data set obtained from a heat treatment performed in the hybrid HT‐MR system at the Charité Medical School is used to visualize the error amplification.Results:The regularization leads to a significantly improved accuracy of the predicted electric fields and temperatures compared to an unregularized approach. The BHTE approximation enables highly accurate temperature predictions in real‐time.Conclusions:Regularization proves to be necessary to identify electromagnetic field parameters. The proposed method is able to reproduce measurements without overfitting to the noise in the MR measurements and results in an improved treatment planning.
Virtual eversion and rotation of colon based on outer surface centerline
Authors: Zhang Danfeng , Zhao Jun , Lu Lin , Li Lei , Wang Zhizhong 
Published: September 2010

Purpose:Virtual eversion turns the colon's inner surface to its outside while maintaining the original colon path. The virtually everted colon allows both global and local views of the mucosal surface for observation. However, the conventional colon's inner surface centerline commonly used in virtual colonoscopy and virtual flattening is not suitable for virtual eversion. Therefore, the colon's outer surface centerline is introduced for virtual eversion to produce a more accurate representation.Methods:An improved level set segmentation method is presented for generating the colon's outer surface. To achieve eversion with fewer errors, the centerline of the colon's outer surface is employed in the proposed virtual eversion method instead of the inner surface centerline. A hybrid sampling method is designed to accelerate the eversion. Virtual rotation is introduced to visualize the lateral and rear views of the colon better. The gathered structures in the high curvature regions can be separated by virtual rotation.Results:The proposed methods were validated using two three‐dimensional phantoms and 87 CT data sets. A study on the observation performance of the everted data showed that the reading times were (63% of time reduction for phantom A, 65% of time reduction for phantom B, and 77% of time reduction for CT data) less than those using virtual colonoscopy, while maintaining the sensibility. The incidence of improperly everted regions in the virtual eversion based on the outer surface centerline was 71% less than that based on the inner surface centerline.Conclusions:The virtual eversion based on the outer surface centerline is more accurate than the one based on the inner surface centerline whether the colon's inner surface is smooth or ragged. The time required for polyp detection using the virtual eversion is considerably less than that using the conventional virtual endoscopy. Virtual eversion and virtual rotation are promising methods for the rapid location of colonic polyps. Together with virtual colonoscopy and virtual flattening, virtual eversion and virtual rotation can be integrated to produce a powerful system for diagnosing colonic lesions.
Apparent absence of a proton beam dose rate effect and possible differences in RBE between Bragg peak and plateau
Authors: Matsuura Taeko , Egashira Yusuke , Nishio Teiji , Matsumoto Yoshitaka , Wada Mami , Koike Sachiko , Furusawa Yoshiya , Kohno Ryosuke , Nishioka Shie , Kameoka Satoru , Tsuchihara Katsuya , Kawashima Mitsuhiko , Ogino Takashi 
Published: September 2010

Purpose:Respiration‐gated irradiation for a moving target requires a longer time to deliver single fraction in proton radiotherapy (PRT). Ultrahigh dose rate (UDR) proton beam, which is 10–100 times higher than that is used in current clinical practice, has been investigated to deliver daily dose in single breath hold duration. The purpose of this study is to investigate the survival curve and relative biological effectiveness (RBE) of such an ultrahigh dose rate proton beam and their linear energy transfer (LET) dependence.Methods:HSG cells were irradiated by a spatially and temporally uniform proton beam at two different dose rates: 8 Gy/min (CDR, clinical dose rate) and 325 Gy/min (UDR, ultrahigh dose rate) at the Bragg peak and 1.75 (CDR) and 114 Gy/min (UDR) at the plateau. To study LET dependence, the cells were positioned at the Bragg peak, where the absorbed dose‐averaged LET was, and at the plateau, where it was . After the cell exposure and colony assay, the measured data were fitted by the linear quadratic (LQ) model and the survival curves and RBE at 10% survival were compared.Results:No significant difference was observed in the survival curves between the two proton dose rates. The ratio of the RBE for CDR/UDR was at the Bragg peak and at the plateau. On the other hand, Bragg peak/plateau RBE ratio was for UDR and for CDR.Conclusions:Present RBE can be consistently used in treatment planning of PRT using ultrahigh dose rate radiation. Because a significant increase in RBE toward the Bragg peak was observed for both UDR and CDR, further evaluation of RBE enhancement toward the Bragg peak and beyond is required.