<p>In the United States, heart failure is a leading cause of hospitalization. The medical industry places great emphasis on diagnosing heart disease through cardiac metrics like ejection fraction. Left ventricular ejection fraction is a commonly used diagnostic indicator for heart efficiency and is measured with echocardiography through different volume calculation techniques. However, ejection fraction results can drastically vary from one examiner to another. Generally cardiologists still give ejection fraction measurements a plus or minus 10 percent error range. </p><p>A program developed at Duke called 4DViz is robust enough for users to process 3D ultrasound data. 4DViz allows examiners to determine heart chamber volumes by constructing a surface model over an imaged heart chamber with many mouse click inputs. Through 4DViz programming, a viable approach for calculating ejection fraction is attempted in this thesis. Using feature tracking, surface drawing, and voxel filling, the new approach aims to reduce examiner input and improve ejection fraction consistency. Water filled balloons were used to calibrate the algorithm's parameters. In testing, several volunteers were asked to use the 4DViz. Their results are compared to volume measurements where user input was standard. The results show promise and may remove some of the inconsistency behind ejection fraction measurements.</p> / Thesis

After a Radiological Dispersal Device (RDD) event, there will not be time to transport people to a whole-body-counter (WBC), since it is a specialized instrument. This work will assess the feasibility of using handheld spectrometers for measuring the radioactivity that may have been inhaled by a victim as a consequence of an RDD event. Measurements were made with a handheld isotope identifier using a slab phantom and several radioactive point sources. A Lawrence Livermore National Laboratory (LLNL) Realistic Torso Phantom and a set of phantoms based on Medical Internal Radiation Dose (MIRD) reports were also used in this work. These phantoms include the human skeleton and have tissue-equivalent organs. Computational models were developed of all of the phantoms using the Monte Carlo Transport code MCNP. After validation of the computer model, MCNP runs were conducted using other sources that are likely to be used in a RDD. Calculations were then done to find the Minimum Detectable Activity (MDA) of all sources used. The Minimum Detectable Dose (MDD) was then calculated for the MIRD phantoms at various times after inhalation.

Medical Imaging era is coming. The volume of business of the Department of Radiation Diagnosis is flourishing, and it drives overall hospital revenue to increase greatly. Thus, it is more important to maintain and promote the quality of medical services in hospital management. In this study, it used PZB model and referred to the SERVQUAL to design the questionnaire. It got the five dimensions for "tangible", "guaranteed", "reliability", "reactive" and "care" and twenty factors to explore the quality of service. A Department of Diagnostic Radiology of regional teaching hospital in Kaohsiung area as the scope of the study, it will be an important basis and reference to improve the quality of service according to the valid questionnaires to analyze the gap of the attention degree between medical staffs and patients for the medical service quality(gap 1), and the gap of the attention degree and the satisfaction to the medical service quality(gap 5), and the relationships between basic information of patients and satisfaction with the IPA analysis showing the service quality items distribution. In gap one, only the "reliability" and "tangible" dimensions in the five dimensions have positive gap and the dimension of "tangible" has the biggest. And ten results in 20 factors show that the attention degree of the subjects is greater than that of the medical staff, but there are no significant differences. In gap five, the five dimensions are all positive gaps and "reactive" dimensions is the biggest. In 20 factors, the subjects with the attention degree of the quality of medical services are greater than satisfaction, and in which there are 17 significant differences. Gap one and gap five have the maximum gap value both in the factor of "convenient transportation and easy parking to the hospital.¡¨ In addition, for the IPA analysis, "medical staffs can satisfy my immediate needs¡¨ fell to the quadrant of ¡§Concentrate Here¡¨. Finally, according to the results, we have the following conclusions: First, patients attach more importance to intangible service. Second, service of the medical staff begins from the heart. Third, mental cognitive of the medical staff will influence their work performance. We also have the following five suggestions: First, Improve traffic convenience. Second, strengthen the learning courses for the quality of health care personnel service. Third, implement the mechanism of service performance. Fourth, arrange the opportunities to service sharing and review. Fifth, establish a feedback way for patints.

This dissertation presents the research performed to develop an optical model, improve some design parameters, and analyze the performance of the UA modular gamma camera. Initially we provide a brief background on nuclear medical imaging with scintillation cameras. The key hardware components of a camera are introduced, and some of the fundamental physics involved in the detection of gamma rays is explained. Then we describe a stand-alone modular camera imaging system that was developed to image human breasts in the clinic. The hardware and software components, calibration procedure, and general operation of the system are detailed. We explain the concepts of position estimation and scatter rejection and note how they have been applied to imaging with the UA modular gamma camera. Position estimation uses the output signals of the camera to determine where an incident gamma ray interacted within the camera, and scatter rejection uses the signals to decide whether or not an incident gamma ray underwent scattering prior to being detected by the camera. Then we present an analytical optical model of the UA modular gamma camera. Taking into account physical and optical properties of the camera components, the model performs radiometric calculations to estimate the mean response of the camera to a scintillation event anywhere within the scintillation crystal. The results of several studies using the optical model to test and improve some camera design parameters are reported. Finally, we demonstrate how straightforward signal detection theory can be used to evaluate the performance of a modular gamma camera for the task of detecting signals in noisy backgrounds. Guided by the preliminary design of a dedicated breast imaging system, estimates of how well the UA modular gamma camera can detect lesions within human breasts were generated.

The mandibular condyles represent important growth sites within the facial skeleton. Condylar growth is not a pacemaker of mandibular development, but it provides regional adaptive growth that is of considerable clinical significance, as the condyle’s upward and backward growth movement regulates the anteriorly and inferiorly directed displacement of the mandible as a whole. Orthopedic problems of the temporomandibular joint (TMJ), such as displacement of the TMJ disk, are common in the adolescent population. Clinical studies of mandibular asymmetry and mandibular retrognathia in adults as well as in children and adolescents, have reported an association with coexisting non-reducing displacement of the TMJ disk without identifying the cause and effect. Through experimental studies causality has been established, and unilateral affliction during growth has been shown to retard ipsilateral mandibular development with facial asymmetry as the sequel. It was hypothesized that bilateral non-reducing TMJ disk displacement during growth would impair mandibular development bilaterally, resulting in mandibular retrognathia. TMJ disk displacement has repeatedly been demonstrated to induce histological reactions of the condylar cartilage. An additional assumption was therefore that a non-deranged TMJ disk function is crucial for the maintenance of the growing condyle’s biophysical environment, and that a connection ought to exist between the amount of condylar cartilage changes caused by TMJ disk displacement and the amount of subsequent adverse mandibular growth. It was also hypothesized that non-reducing displacement of the TMJ disk in growing individuals would result in qualitative and quantitative changes of the condylar subchondral bone. An improved experimental cephalometric method was developed in order to optimize the reliability of longitudinal radiographic evaluation of fast growing small animals. Bilateral non-reducing TMJ disk displacement was surgically created in ten growing New Zealand White rabbits, with ten additional rabbits serving as a sham operated control group. The amount and direction of craniofacial growth was followed over time in serial cephalograms, aided by tantalum implants in the jaws. The study period was chosen to correspond to childhood and adolescence in man. The assessed growth of each side of the mandible was correlated to the histological feature of ipsilateral condylar cartilage at the end of the growth period. The amount and composition of subchondral bone from three regions of interest in the condyle, and the expression of local growth factors in the adjacent condylar cartilage was evaluated. The results verified that bilateral non-reducing TMJ disk displacement retarded mandibular growth bilaterally; the extent corresponding to mandibular retrognathia in man. Displacement of the TMJ disk during the growth period induced condylar cartilage adaptive reactions that were associated with both an adverse amount and direction of mandibular growth, manifesting in a retrognathic mandibular growth pattern. Growth impairment fluctuated over time, with the most striking retardation occurring during periods of increased general growth, implying a local growth reduction explicitly counteracting general hormonal growth acceleration. A significant decrease of the total amount of subchondral bone, in spite of a general increase of new bone formation in the experimental condyles, pointed to a reparative compensation for an extensive resorption of subchondral bone due to displacement of the TMJ disk, but not to the extent that normal growth would be maintained. These results constitute an explanation for the adverse mandibular development following non-reducing TMJ disk displacement in growing individuals. This project has shown that non-reducing displacement of the TMJ disk during growth has significant consequences on facial development. The findings strongly advocate early and accurate diagnosis and treatment of TMJ disk displacement in the adolescent population, thereby presumably reducing the need for future orthodontic and surgical craniofacial corrective therapy. The results furthermore enhance the need for full appraisal of TMJ disk function in the adolescent population during orthodontic functional therapy, as the condylar cartilage and subchondral bone reactions to a concomitantly displaced non-reducing TMJ disk must be expected to interfere with the intended growth stimulating treatment. The findings of intact articular layers in spite of gross histological and morphological soft and hard tissue changes as a sequel to TMJ disk displacement in growing individuals, implicate a clinical risk of false positive radiographic diagnosis of degenerative changes of the TMJ in children and adolescents.

Bakgrund: Trots en snabb utveckling av undersökningsmetoderna inom IR har inte strålskydden utvecklats i samma takt. Den joniserande strålning som förekommer på modaliteten kan medföra en hälsorisk för personalen därav finns det stråldosgränser att hålla sig inom för att minimera risken för yrkesrelaterade strålskador. För att förebygga risken för strålningsrelaterade skador är det viktigt att undersöka olika metoder av skydd för att optimera personalens strålsäkerhet.Syfte: Syftet med studien var att belysa metoder för att reducera stråldosen för personal verksam vid interventionell radiologi.Metod: Sökningarna av artiklarna genomfördes i databaserna CINAHL, PubMed och Scopus varav 13 studier valdes ut, kvalitetsgranskades samt analyserades kritiskt med utgångspunkt från en innehållsanalys.Resultat: Resultatet visade på 11 strålskyddsmetoder för personalen: blyförkläde med thyroideablyskydd, Suspended Personal Radiation Protection System, blyglasögon, blyhandskar, takfäst blyglas, golvbaserade blyglas, patientblyskydd, direktdigital dosimeter, avstånd till patienten genom automatisk kontrastspruta, vismut-bariumöverdrag samt erfarenhet och information.Konklusion: Trots att metoderna enskild reducerade stråldosen till personalen skulle det kunna vara mer effektivt att kombinera olika strålskydd för bättre reduceringseffekt. Genom resultatet anser författarna att fortsatt forskning krävs inom utvecklandet av nya strålskydd som är mer ergonomiska mot personalen samt hur strålskydden påverkar patienterna både fysiskt och psykiskt. / Background: Despite the fast development of examination methods in IR, the development of the radiation protections has not been as rapid. Ionizing radiation that occurs in the modality can be a threat to the personnel of which there are radiation dose limits to keep within in order to minimize the risk of occupational radiation damage. In order to minimize the risk of occupational radiation damage, it is of importance to explore different methods to optimize the radiation protection for the personnel.Purpose: The aim of this study was to illuminate methods to reduce the radiation dose to personnel working in interventional radiology.Method: Searches were conducted in the databases CINAHL, PubMed and Scopus from which 13 studies were selected, viewed and analyzed with basis from a content analysis.Results: The results showed 11 different radiation protection methods for the staff were identified and those were: lead apron with a thyroid lead shield, Suspended Personal Radiation Protection System, leaded eyeglasses, leaded gloves, ceiling suspended leaded shield, rolling leaded shield, patient lead shield, real-time dosimeter, distance to the patient through an automatic power injector, bismuth - barium shielding and experience and information.Conclusion: Although the methods individual reduced radiation dose to the personnel, it might be more efficient to combine the various radiation protections for better reduction effect. The authors recommend that further research is required in the development of new radiation protection that is more ergonomic to the personnel and how the radiation shields affects patients both physically and psychologically.

We hypothesize that acid-outside transplasmalemmalar pH gradients, typical of those found in drug-insensitive breast tumors, will result in drug resistance by the exclusion of weakly basic chemotherapeutic agents via ion trapping. We tested our hypothesis in vitro by evaluating pH dependent cytotoxicity of various clinically relevant chemotherapeutic drugs in the MCF-7 human breast adenocarcinoma cell line. The results of this work were consistent with our hypothesis, namely that (i) weak acids are more toxic in acidic extracellular media, (ii) weak bases are more toxic in basic extracellular media, and (iii) large lipophilic molecules are unaffected by pH change. Both doxorubicin and mitoxantrone were found to have enhanced intracellular accumulation in alkaline media, with the effect being more significant on mitoxantrone. In contrast, only mitoxantrone had a partition coefficient that was appropriately high and compatible with our ion-trapping model. Moreover, the pH dependent cytotoxicity and drug accumulation of mitoxantrone, doxorubicin and chlorambucil remained constant even in drug resistant cell lines such as the MCF-7D40 and MCF-7mitox cell lines. In an MCF-7 tumor/SCID mouse model the in vivo biodistribution of doxorubicin in alkalotic mice was evaluated. No significant difference in doxorubicin accumulation was observed in the tumor compared to controls. We evaluated the anti-tumor activity of mitoxantrone in the C3H model system and found that metabolic alkalosis significantly increased both the tumor growth delay and the log cell kill. In our MCF-7/SCID model system, doxorubicin combined with chronic metabolic alkalosis resulted in a reduction in the rate of tumor regrowth. In vivo mitoxantrone C3H mouse toxicity studies were performed with and without metabolic alkalosis. The LD50 and average weight loss per group remained constant with or without alkalosis. In conclusion, mitoxantrone has a pH-dependent behavior consistent with ion-trapping. (Abstract shortened by UMI.)

Radiology departments are implementing conversion from the use of hard copy film in favor of digital imaging. New digital acquisitions are increasing the efficacy of radiological imaging. The outputs of new modalities such as magnetic resonance (MR) and computed tomography (CT) are digital. They both involve gathering information that allows reconstructing cross sectional projections of internal structures and displaying them as digital images. Other technologies, e.g., computed radiography (CR), can provide digital radiographic data that replaces analog projection radiography. To date, the processed digital data is still transferred to film to provide a typical radiographic film in appearance. The film is presented to the doctor for diagnostic review. The research in this dissertation is concerned with making a film-less department. It specifically addresses problems in presenting CR images to the physician. The goal of this research is to create a computer recognition algorithm that will automatically recognize the orientation and discriminate between the lateral and posteroanterior view of digital chest radiographs image. The algorithm maintains 91.9% accuracy rate. The recognition takes .15 second per image.

Ultraviolet-B (UVB) irradiation is a major cause of human non-melanoma skin cancer. Transcription factor activator protein-1 (AP-1) plays an important role in tumor promotion. The mechanism of UVB induced tumor promotion may be through AP-1 activation. In this dissertation, the molecular mechanisms of UVB induced AP-1 activation were pursued in a human keratinocyte cell line, HaCaT. UVB induced AP-1 activation was observed by gel shift assays and transactivation assays. c-Fos and Jun D were the main components of the bound AP-1 complexes. Inhibition of RNA and protein synthesis significantly abrogated UVB induced AP-1 DNA binding. Further investigation revealed a correlation between increased AP-1 activity and c-fos gene expression after UVB. These results suggested that increased c-fos expression may play an important role in UVB induced AP-1 activation. To further examine the mechanism of UVB induced c-fos expression, the UVB signaling pathways were studied. Two members of mitogen-activated protein kinase (MAPK) family, p38 and extracellular signal-regulated protein kinase (ERK), were activated after UVB. Blocking p38 significantly abrogated UVB induced c-fos expression. Inhibiting ERK partially abrogated UVB induced c-fos expression. These data suggested that both p38 and ERK were required in UVB induced c-fos expression in human keratinocytes. Furthermore, p38 appeared to play a more important role than ERK in this process. Since c-fos expression may play an important role in UVB induced AP-1 activation, and AP-1 activation is known to play a role in tumor promotion, both p38 and ERK could be potential targets for chemoprevention of skin cancer. (-)-Epigallocatechin gallate (EGCG), the major polyphenol isolated from green tea, has been shown to inhibit UVB induced tumorigenesis. However, the mechanisms that underline the inhibitory effects of EGCG are not well understood. In this study, EGCG was found to inhibit UVB induced AP-1 transactivation and c-fos expression. Furthermore, EGCG inhibited UVB induced p38 activation. Thus, suppression of p38 signaling cascade was the mechanism of EGCG's inhibitory effect on UVB induced c-fos expression, which may further explain its inhibitory effect on UVB induced AP-1 activation.

Semiconductor-based gamma-ray-imaging detectors are under development for use in high-resolution nuclear medicine imaging applications. These detectors, based on cadmium zinc telluride, hold great promise for delivering improved spatial resolution and detection efficiency over current methods. This dissertation presents work done on three fronts, all directed toward enhancing the practicality of these imaging devices. Electronic readout systems were built to produce gamma-ray images from the raw signals generated by the imagers. Mathematical models were developed to describe the detection process in detail. Finally, a method was developed for recovering the energy spectrum of the original source by using maximum-likelihood estimation techniques. Two electronics systems were built to read out signals from the imaging detectors. The first system takes signals from a 48 x 48-pixel array at 500 k samples per second. Pulse-height histograms are formed for each pixel in the detector, all in real time. A second system was built to read out four 64 x 64 arrays at 4 million pixels per second. This system is based on digital signal processors and flexible software, making it easily adaptable to new imaging tasks. A mathematical model of the detection process was developed as a tool for evaluating possible detector designs. One part of the model describes how the mobile charge carriers, which are released when a gamma ray is absorbed in a photoelectric interaction, induce signals in a readout circuit. Induced signals follow a "near-field effect," wherein only carriers moving close to a pixel electrode produce significant signal. Detector pixels having lateral dimensions that are small compared to the detector thickness will develop a signal primarily due to a single carrier type. This effect is confirmed experimentally in time-resolved measurements and with pulse-height spectra. The second part of the model is a simulation of scattering processes that take place when a gamma ray is absorbed within the detector volume. A separate simulation predicts the spreading of charge carriers due to diffusion and electrostatic forces. The models are used in a technique to improve the energy resolution of the detectors by estimation of the source spectrum using the Expectation-Maximization algorithm.