bluuebunny/crossref_metadata_2025_split huggingface dataset:
Many‐valued Logic in Multistate and Vague Stochastic Systems
Authors: Sellers Kimberly F. , Singpurwalla Nozer D. 
Published: July 2008

SummaryThe state of the art in coherent structure theory is driven by two assertions, both of which are limiting: (1) all units of a system can exist in one of two states, failed or functioning; and (2) at any point in time, each unit can exist in only one of the above states. In actuality, units can exist in more than two states, and it is possible that a unit cansimultaneouslyexist in more than one state. This latter feature is a consequence of the view that it may not be possible to precisely define the subsets of a set of states; such subsets are calledvague. The first limitation has been addressed via work labeled ‘multistate systems’; however, this work has not capitalized on the mathematics of many‐valued propositions in logic. Here, we invoke its truth tables to define the structure function of multistate systems and then harness our results in the context of vagueness. A key contribution of this paper is to argue that many‐valued logic is a common platform for studying both multistate and vague systems but, to do so, it is necessary to lean on several principles of statistical inference.
Early intervention in bipolar disorder, part II: therapeutics
Authors: Salvadore Giacomo , Drevets Wayne C. , Henter Ioline D. , Zarate Carlos A. , Manji Husseini K. 
Published: July 2008

AbstractRecent evidence has shown that early pharmacological and psychosocial treatment dramatically ameliorates poor prognosis and outcome for individuals with psychotic disorders, reducing conversion rates to full‐blown illness and decreasing symptom severity. In a companion paper, we discussed methodological issues pertaining to early intervention in bipolar disorder (BPD), reviewed clinical studies that focus on high‐risk subjects as well as first‐episode patients, and reviewed findings from brain imaging studies in the offspring of individuals with BPD as well as in first‐episode patients.In this paper, we discuss how drugs that modulate cellular and neural plasticity cascades are likely to benefit patients in the very early stages of BPD, because they target some of the core pathophysiological mechanisms of this devastating illness. Cellular and molecular mechanisms of action of agents with neurotrophic and neuroplastic properties are discussed, with a particular emphasis on lithium and valproate. We also discuss their potential use as early intervention strategies for improving symptoms and functioning in patients in the earliest stages of BPD, as well as high‐risk individuals.
Family strengths: a potential determinant of the duration of untreated psychosis among hospitalized African‐American first‐episode patients
Authors: Goulding Sandra M. , Leiner Amy S. , Thompson Nancy J. , Weiss Paul S. , Kaslow Nadine J. , Compton Michael T. 
Published: July 2008

AbstractAim: Evidence suggests that treatment delay, represented by the duration of untreated illness (DUI) and the duration of untreated psychosis (DUP), may be a potentially powerful determinant of the early course of primary psychotic disorders. Yet, research on the predictors of treatment delay has only just begun. To date, there are virtually no empirical data on the relationship between family functioning and treatment delay in the context of first‐episode psychosis. In this study, it was hypothesized that family strengths would be inversely correlated with DUI and DUP; and families of patients with a short DUI/DUP would have greater family strengths than those of patients with a long DUI/DUP.Methods: Family strengths (including pride and accord dimensions), DUI and DUP were assessed in 34 African Americans hospitalized for first‐episode psychosis and their respective 34 family members most involved in initiating care.Results: The total score of the Family Strengths scale and the accord subscale score were significantly inversely correlated with both DUI and DUP, although the correlation between the pride subscale score and DUI/DUP was not as strong and failed to reach statistical significance. Similarly, the family members of patients with a short DUI/DUP had higher family strength scores than those of patients with a long DUI/DUP.Conclusions: Given the dearth of research on the functioning of families beginning to initiate care for individuals with first‐episode psychosis, it is imperative to further clarify the role family characteristics may play in understanding treatment delay (DUI/DUP) and in the development of preventive interventions to facilitate early intervention for at‐risk populations.
Clinical and neurocognitive course in early‐onset psychosis: a longitudinal study of adolescents with schizophrenia‐spectrum disorders*
Authors: Wozniak Jeffrey R. , Block Erin E. , White Tonya , Jensen Jonathan B. , Schulz S. Charles 
Published: July 2008

AbstractAim: Adolescents with psychotic disorders show deficits in IQ, attention, learning and memory, executive functioning, and processing speed that are related to important clinical variables including negative symptoms, adaptive functioning and academics. Previous studies have reported relatively consistent deficits with varying relationships to illness status and symptoms. The goals of this study were to examine these relationships in a larger sample at baseline, and also to examine the longitudinal course of these deficits in a smaller subset of adolescents.Method: Thirty‐six subjects, aged 10 to 17 years, were included at baseline. All had Diagnostic and Statistical Manual‐Fourth Edition diagnoses of schizophrenia, schizoaffective disorder, schizophreniform disorder and psychosis – not otherwise specified, as determined by Kiddie‐Schedule for Affective Disorders and Schizophrenia for School‐Age Children structured interviews. Patients were administered a neuropsychological battery, and Positive and Negative Syndrome Scale ratings were completed at baseline and again at 1 year (n = 14). Most participants were inpatients at baseline, and 13 of 14 were on atypical antipsychotic medication during both sessions.Results: At baseline, the patients demonstrated impairments in working memory, processing speed, executive function and verbal learning. No significant cognitive change was detected at 1‐year follow‐up. In contrast, clinical symptoms were variable across 1 year, with an improvement in positive symptoms at 1 year. No relationships between clinical and cognitive symptoms were observed, with the exception of baseline IQ predicting negative symptoms at 1 year.Conclusions: Young patients with schizophrenia‐spectrum disorders displayed neurocognitive impairments at baseline. Despite measurable fluctuations in clinical symptoms over the year, no significant changes were measured in cognition. Lower IQ at baseline was predictive of more negative symptoms at 1 year.
SU‐EE‐A3‐05: A Protocol to Extend On‐Board Cone‐Beam CT Longitudinal Coverage with Multiple Orbits
Authors: Zheng D , Lu J , Wu J , Weiss E , Dogan N , Williamson J 
Published: July 2008

Purpose: To develop, evaluate and optimize a protocol for acquiring on‐board cone‐beam CT (CBCT) images for larger longitudinal coverage than the maximum 14 cm coverage allowed by the Varian OBI half‐fan single‐orbit mode. Extended coverage is needed to fully image many standard pelvic, thoracic, and head‐and‐neck treatment volumes and to support such tasks as deformable image registration and dose reconstruction on serial CBCT images. Method and Materials: Multiple Varian single‐orbit data acquisitions separated by couch shifts were performed with small overlaps to provide the desired coverage. Simple approaches to aligning the two image volumes based on the nominal couch shift were validated against rigid image registration based upon orthogonal radiographic projections. An automatic algorithm was devised to decode the DICOM headers of the original slices and get corresponding position information, subsequently join the volumes, and finally rewrite the headers so that the resultant CBCT image set will be correlated as a single DICOM image volume. Validation of the volume reconstruction was performed with AP/PA radiographs and CatPhan QA phantom to evaluate the combining accuracy and the image quality in the abutment region where data sampling violates Tuy's data sufficiency condition. Results: The above protocol successfully provides OBI CBCT images with any desirable longitudinal coverage. An optimized protocol is implemented clinically, based upon the dose consequences and application simplicity. Conclusion: A practical method was developed to effectively extend the OBI longitudinal coverage, which improved the applicability of the OBI CBCT images in image‐guided adaptive radiation therapy.This work was supported by NIH P01 CA116602.
SU‐GG‐I‐12: Effect of Geometric Unsharpness On the Reconstructed Image in Region of Interest (ROI) μCT
Authors: Wang W , Patel V , Keleshis C , Bednarek D , Hoffmann K , Rudin S 
Published: July 2008

Purpose: To demonstrate the effects of variation of focal‐spot size and magnification on the spatial resolution of reconstructed images of a micro‐computed tomography (μCT) system which is attached to a standard angiographic C‐arm gantry to enable Region‐of‐Interest cone‐beam CT (ROI‐CBCT). Method and Materials: High‐resolution ROI projection data of a vascular phantom were acquired using a new high‐sensitivity, microangiographic fluoroscope (HSMAF) detector (35 μm pixels), which was attached to the C‐arm gantry and able to be positioned in front of a standard full field‐of‐view, low‐resolution commercial flat‐panel detector (FPD) (194 μm pixels). The HSMAF consists of a CsI phosphor viewed by a 4‐cm diameter light image‐intensifier with large variable dynamic range whose output is coupled via a fiber‐optic taper to a CCD camera. The test objects in the vascular phantom were a stent (100 micron struts) inside of a catheter in a cylindrical water bath. The phantom was placed on a portable test platform (PTP) enabling CBCT image acquisition by the HSMAF every 1°. Six μCT runs were performed using two focal‐spot sizes (0.3 and 0.6 mm) and three magnification factors (1.15, 1.29, and 1.48). Profiles were extracted from the reconstructed struts, and the full width half‐maximum (FWHM) were measured. Results: The reconstructed data show that using the optimal configuration (smallest magnification with small focal spot) compared to the worst configuration (largest magnification and the large focal spot) resulted in a 47% reduction in the FWHM in the object plane (175 μm versus 375 μm). Conclusion: Micro‐CBCT can provide more accurate visualization of fine device features; however, geometric unsharpness and/or large focal spots can substantially degrade resolution reducing the quality of the μCBCT reconstructions.(Research sponsored by: NIH Grants R01‐NS43924, R01‐EB002873, Toshiba Medical Systems Corporation)
SU‐GG‐I‐25: An Image Quality Comparison Study Between XVI and OBI CBCT Systems
Authors: Kamath S , Song W , Chvetsov A , Li J , Ozawa S , Liu C , Palta J 
Published: July 2008

Purpose: To evaluate image quality on the X‐ray Volumetric Imager (XVI®, Elekta Medical Systems) and the On‐Board Imager (OBI®, Varian Medical Systems) using a CatPhan® phantom in a single institution setting. Method and Materials: We evaluated four major image quality indices, including high and low contrast resolution, noise, and contrast‐to‐noise (CNR) ratio. For the XVI unit, the four manufacturer‐supplied protocols were measured. For the OBI unit, full bow‐tie and half bow‐tie filters were used in combination with the “full‐fan” and “half‐fan” modes. The mAs was varied for each protocol. High contrast resolution was evaluated using number of line pairs visible per cm and low contrast resolution was evaluated using the visibility of low resolution disks. Noise was computed over circular regions of interest (ROIs) on the uniformity module. CNR was calculated using a polystyrene insert and the background of module CTP404. The images were analyzed using MATLAB. Results: Up to 10 line pairs per cm are visible on OBI for high mAs settings and so are most low contrast discs. 2 line pairs per cm and none of the low contrast discs are visible on XVI. Noise values fall from 35 to 6 on OBI and vary between 10 and 3 for “prostate” protocol on XVI with increasing mAs. On OBI, CNR steadily increased from 4 to 20 with increasing mAs. For the “prostate” protocol on XVI, CNR varies from 10 to 23 and generally increases with mAs. For the four XVI protocols evaluated, mean pixel values in ROIs are found to decrease with mAs. Conclusion: Image quality parameters are generally found to be better on OBI as compared with XVI for clinical protocols. However, this is important to be viewed in the context of the observation that OBI generally delivered higher doses than XVI.Research sponsored by Elekta Inc.
SU‐GG‐I‐47: A New Limited‐Angle CT Reconstruction Method Based On Total‐Variation Minimization
Authors: Zhang J , Ren L , Zhou S , Yin F 
Published: July 2008

Purpose: To develop a new CT reconstruction algorithm based on Total‐Variation (TV) minimization. The new algorithm is specifically designed for limited angle reconstruction to alleviate volume information loss caused by incomplete projections. Method and Materials: TV is defined as the summation of the gradients between adjacent pixels. A nonlinear conjugate gradient algorithm is used to minimize TV and projection error simultaneously. Pixel Signal‐to‐Noise Ratio (PSNR) was used to quantitatively evaluate reconstruction quality of a Shepp‐Logan phantom. Head and neck CT images were reconstructed from simulated projections to demonstrate reconstruction quality at different scan angle. The effects of weighting factors for TV and projection frequency were investigated. Results: The algorithm can reconstruct good quality images with the scan angle as low as 60 degree. With 90‐degree projections, the reconstructed Shepp‐Logan phantom has a high PSNR of 17 dB. Weighting factors for TV were determined through simulations. Image qualities were improved by weighting more high frequency of the projection data. In simulation tests using head/neck simulated projections, volume information can be recovered accurately from 60‐degree projections. Conclusion: The TV‐based reconstruction algorithm improves the quality of limited angle CT reconstruction.Research sponsored by a Varian research grant.
SU‐GG‐I‐52: Conversion of On‐Board Digital TomoSynthesis (DTS) to HU Values
Authors: Yoo S , Wu Q , Godfrey D , Ren L , Yin F 
Published: July 2008

Purpose: To investigate a method to convert the pixel values of DTS images to HU values with reference HU values from CT images. Method and Materials: This study included CT and DTS images of two phantoms (Catphan and a chest phantom) and three patients (prostate, head‐and‐neck, and lung). Cone‐beam radiograph projections were acquired to reconstruct the limited angle DTS images, which were expressed in arbitral pixel values after a Feldkamp‐type technique. Regions of interest (ROIs) in the CT images were selected for low‐ and high‐density areas, and HU values were measured in the ROIs. DTS pixel values were measured for the corresponding ROIs in the DTS images. A linear regression was performed using the DTS pixel values (D) as the dependent variable in terms of the HU (H) for each phantom and patient independently. The linear regression was applied to the DTS images in order to convert the DTS pixel values into HU values. DTS images expressed in HU values were compared to CT images. Results: The method proposed in this study is simple and feasible to convert DTS images in HU values. However, the DTS image slices certainly contain different image contents than corresponding CT image slices. The out‐of‐plane objects smear into the plane of interested in DTS images and affect HU values of in‐plane objects. Thus, HU values do not represent correct tissue materials due to underlying/overlaying tissues. Conclusion: This method could be used to convert DTS images in HU values and useful to understand DTS images for positioning purpose. However, DTS images in HU values should not be used for planning purposes due to smearing effect of underlying/overlaying objects.Research partially sponsored by grants from NIH and Varian Medical Systems.
SU‐GG‐J‐102: Image Guided Radiotherapy of the Cervix with Biomechanical Model‐Based Deformable Registration
Authors: Brock K , Moseley J , Stewart J , Lim K , Xie J , Lundin A , Rehbinder H , Fyles A , Milosevic M , Jaffray D 
Published: July 2008

Purpose: Evaluate the potential geometric and dosimetric improvements in image‐guided radiotherapy of the cervix using deformable registration. Method and Materials: Weekly MR images obtained prior to and during radiotherapy for 29 women with cervix cancer were selected. The bladder, rectum, and GTV were contoured on each image following rigid, bony anatomy based registration. Deformable registration was performed using MORFEUS, a multi‐organ finite element model‐based deformable registration algorithm. The bladder and rectum were explicitly registered between planning and each week. The GTV displacement was estimated by the biomechanical model and the bladder and rectum displacement. The improvements using couch shifts based on deformable registration were assessed using 3 metrics: 1) improvement in localization of tumor COM, 2) improvements in GTV coverage by the PTV, and 3) improvements in the dosimetric coverage of the GTV and CTV accumulated over the treatment using deformable dose accumulation in ORBIT Workstation. Results: The average error in COM alignment of the tumor improved by 0.3, 2.1, and 1.1 mm in the LR, AP, and SI directions, respectively with deformable registration. Following bony registration, 69% of GTVs were at least 95% covered by the PTV, improving to 86% following deformable registration. Dosimetric coverage of the GTV improved from 93% of patients achieving 98% volume coverage by 4900 cGy to 100% following deformable registration‐based couch shift for tumor COM correction. CTV coverage improved from 83% of patients achieving 98% volume coverage by 4750 cGy to 93% following deformable registration‐based couch shift for tumor COM correction. Conclusion: A method has been developed to perform deformable registration of surrounding anatomy to calculate the COM of the tumor for application in volumetric image guidance where the tumor is not visible. Both geometric and dosimetric improvements were demonstrated.Supported by RaySearch Laboratories and National Cancer Institute of Canada — Terry Fox Foundation.
SU‐GG‐J‐106: Improved Planar and Megavoltage Cone‐Beam Imaging Using Low‐Z Linear Accelerator Targets
Authors: Orton E , Kelly R , Robar J 
Published: July 2008

Purpose: to examine the effect of using low atomic number (Z) target materials on megavoltage portal and cone‐beam CT (CBCT) image quality. Method and materials: for experimental measurements, four low‐Z targets were installed in a linear accelerator carousel (Varian 2100EX) for the generation of experimental spectra for imaging. The targets were composed of beryllium or aluminum with thicknesses set to approximately 60% of the CSDA range of either 4 MeV or 6 MeV electrons. For CBCT acquisition, the beam and detector were fixed, and a rotation stage was controlled by software to acquire multiple angular projections of phantoms. To examine photon energy spectra and to provide a means for optimizing the imaging system, the beam generation and detector panel were modeled using BEAMnrc/DOSXYZ Monte Carlo package. For 6MV, the beam/detector model was validated by comparing experimental and MC‐generated images of open fields. Results: The modeled, experimental spectra demonstrate the recovery of photons below 150 keV. For the 4 MeV/Be beam, for example, approximately 1/3rd of photons have energies below 60 keV. MC models of planar imaging show significant improvement of image contrast compared to the standard 6MV beam, and suggest that i) of the four energy/target combinations studied, the 4 MeV/Be combination provides the greatest contrast improvement and ii) a modest additional increase in contrast is achieved by removing the copper buildup layer from the detector. Initial low‐Z target CBCT images show improved image contrast; full quantitative results will be presented. Conclusion: The use of megavoltage electron beams combined with low‐Z targets offers the potential for improved image quality, particularly in terms of image contrast. This approach may be promising for improved and highly‐integrated on‐board megavoltage imaging.Conflict of interest: This research has been sponsored by Varian Medical Systems, Incorporated.
SU‐GG‐J‐119: Localization Accuracy of Target Verification System Using Digitial Tomosynthesis (DTS)
Authors: Yan H , Ren L , Godfrey D , Yoo S , Yin F 
Published: July 2008

Purposes: A research platform was developed for target verification using digital tomosynthesis (DTS). To verify its accuracy, a phantom study was conducted and several clinical cases were investigated. Method and Materials: customer‐developed reconstruction and image registration algorithms were implemented in this platform. The existing image reviewing software was employed for the purpose of manual registration. Phantom study was conducted to investigate the target localization accuracy using DTS with respect to different simulated shifts along three directions. In real clinical cases, the registration results of both CBCT‐based and DTS‐based methods were achieved and compared for identify their equivalency. Results: with respect to different simulated shifts of phantom ranging from 1 cm to 5 cm, the high target localization accuracy was obtained which is within 1 mm. The comparison between CBCT‐based and DTS‐based registration results on clinical cases shows that they are nearly identical. The maximal different is less than 0.5 mm and averagely 0.1 mm over three dimensions was observed. Conclusion: DTS is an effective way for fast target localization. With properly setting, the high registration accuracy comparable to CBCT can be achieved. Currently, more effects related to acquisition mode, scan angles, and reconstruction slice thickness, were under investigation. It is expected to present interested user a clear guidance on how to use this new image modality more effectively for image‐guided radiotherapy.Acknowledgements: this study was supported by NIH grant (R21‐CA128368).