Patient Risk-Minimizing Tube Current Modulation in X-Ray Computed Tomography

This dissertation proposes a patient-specific tube current modulation for computed tomography (CT) that minimizes the individual patient risk (riskTCM). Modern CT scanners use automatic exposure control (AEC) techniques including tube current modulation (TCM) to reduce the radiation dose delivered to the patient while maintaining image quality. Today's TCM implementations aim at minimizing the tube current-time (mAs) product as a surrogate for patient dose, which is why they are referred to as mAsTCM hereafter. However, the actual patient risk, e.g., in the form of risk measures such as the effective dose Deff representing the sensitivity of individual organs with respect to ionizing radiation, is not taken into account. In order to be able to optimize the effective dose Deff or another biologically meaningful measure, organ doses must be estimated before the actual CT scan in order to compute an optimized riskTCM curve. This can be achieved using a machine learning approach and based on these information, the new patient risk-minimizing TCM curve can be obtained. The proposed riskTCM algorithm was evaluated in a simulation study for circular scans and compared against the current gold standard method mAsTCM and to a constant tube current as well as an organ-specific tube current modulation technique. The results illustrate that all anatomical regions can benefit from riskTCM and a reduction of effective dose of up to 30% can be expected compared to mAsTCM. Furthermore, riskTCM was extended to a spiral trajectory that is commonly used in clinical routine and initial measurements with phantoms have been performed. The introduction of riskTCM into clinical practice would only require a software update since almost all CT systems are already capable of modulating the tube current

Family Process Through the Prism of Living Donation: Courage, Coercion, Calculus and Coalescence

ABSTRACT FAMILY PROCESS THROUGH THE PRISM OF LIVING DONATION: COURAGE, COERCION, CALCULUS AND COALESCENCE Living donor liver transplantation is a relatively recent worldwide development in the field of transplantation due to a shortage of cadaveric organs. In 1989, the first successful living donor liver transplantation was performed (Gruessner & Benedetti, 2008, p.439) and by 2009 it had become an established way to treat end stage liver disease. The reasons that an individual decides to donate remain poorly understood. There are serious medical and psychological risks to the donor that necessitate careful psychosocial assessment prior to donation. Family processes for selecting a donor must be theoretically as well as clinically explored to refine our understanding of living donation. This study’s intent was to give voice to the experiences of a small number of transplant professionals experienced in working with living donors and their families. The work of the object relations theorists Klein, Kohut, and Winnicott provide background for this qualitative research study while the methods of Weiss (1994) were used to analyze the semi-structured intensive interviews. This research sheds light on the health care professionals’ perceptions of the experience of living liver donors and their families and offers direction for transplant social workers as they guide potential donors and donor families through the donation process

Current Developments in Advocacy to Expand the Civil Right to Counsel

Around the country, state and local bar associations, access to justice commissions, and local advocacy groups are working to expand the right to counsel in their jurisdictions. The passage of three statutes in the past three years is tangible evidence of their efforts. Many civil right to counsel advocates take as their mandate a resolution passed unanimously by the American Bar Association’s House of Delegates two years ago, calling on the government to provide counsel in cases in which “basic human needs are at stake.” This Article describes efforts underway in eleven states to expand the right to counsel, as well as national efforts, and concludes that these efforts promise to result in increased access to the courts for low-income people

Mechanical magnetometry of Cobalt nanospheres deposited by focused electron beam at the tip of ultra-soft cantilevers

Using focused-electron-beam-induced deposition, Cobalt magnetic nanospheres with diameter ranging between 100 nm and 300 nm are grown at the tip of ultra-soft cantilevers. By monitoring the mechanical resonance frequency of the cantilever as a function of the applied magnetic field, the hysteresis curve of these individual nanospheres are measured. This enables to evaluate their saturation magnetization, found to be around 430 emu/cm^3 independently of the size of the particle, and to infer that the magnetic vortex state is the equilibrium configuration of these nanospheres at remanence

Managing Virtual Internships During the Covid-19 Pandemic Era: Implications for Academic Instructors and Business Leaders

During the beginning phase of the COVID-19 Pandemic in late March of 2020 in the United States, two academic instructors at a mid-sized, public university in the Midwest were involved in converting a traditional human resource development internship course into a virtual internship course that they would be teaching in May of 2020. This paper shares the lessons learned by the two instructors along with a summary of a relevant theoretical leadership framework that provides useful insights for academic instructors and business leaders who are or will be managing virtual academic internships in the future. This paper concludes by offering insights and recommendations for academic instructors, business leaders, and students interested in virtual internships

Measuring DHEA-S in saliva: time of day differences and positive correlations between two different types of collection methods

<p>Abstract</p> <p>Background</p> <p>The anabolic steroid, dehydroepiandosterone sulfate (DHEA-S), is secreted from the adrenal cortex. It plays a significant role in the body as a precursor to sex steroids as well as a lesser known role in the hypothalamic pituitary adrenal axis (HPA) response to stress. DHEA-S can be measured reliably in saliva, making saliva collection a valuable tool for health research because it minimizes the need for invasive sampling procedures (e.g., blood draws). Typical saliva collection methods include the use of plain cotton swab collection devices (e.g., Salivette^®) or passive drool. There has been some speculation that the plain saliva cotton collection device may interfere with determination of DHEA-S by enzyme immunoassay (EIA) bringing this saliva collection method into question. Because of the increasing popularity of salivary biomarker research, we sought to determine whether the cotton swab interferes with DHEA-S determination through EIA techniques.</p> <p>Findings</p> <p>Fifty-six healthy young adult men and women aged 18-30 years came to the lab in the morning (0800 hrs; 14 men, 14 women) or late afternoon (1600 hrs; 14 men, 14 women) and provided saliva samples via cotton Salivette and passive drool. Passive drool collection was taken first to minimize particle cross contamination from the cotton swab. Samples were assayed for DHEA-S in duplicate using a commercially available kit (DSL, Inc., Webster, TX). DHEA-S levels collected via Salivette and passive drool were positively correlated (r = + 0.83, p < 0.05). Mean DHEA-S levels were not significantly different between collection methods. Salivary DHEA-S levels were significantly higher in males than in females, regardless of saliva collection method (p < 0.05), and morning DHEA-S values were higher than evening levels (p < 0.05).</p> <p>Conclusions</p> <p>Results suggest that DHEA-S can be measured accurately using passive drool or cotton Salivette collection methods. Results also suggest that DHEA-S levels change across the day and that future studies need to take this time of day difference into account when measuring DHEA-S.</p

Testosterone Trajectories and Reference Ranges in a Large Longitudinal Sample of Male Adolescents

Pubertal dynamics plays an important role in physical and psychological development of children and adolescents. We aim to provide reference ranges of plasma testosterone in a large longitudinal sample. Furthermore, we describe a measure of testosterone trajectories during adolescence that can be used in future investigations of development.We carried out longitudinal measurements of plasma testosterone in 2,216 samples obtained from 513 males (9 to 17 years of age) from the Avon Longitudinal Study of Parents and Children. We used integration of a model fitted to each participant's testosterone trajectory to calculate a measure of average exposure to testosterone over adolescence. We pooled these data with corresponding values reported in the literature to provide a reference range of testosterone levels in males between the ages of 6 and 19 years.The average values of total testosterone in the ALSPAC sample range from 0.82 nmol/L (Standard Deviation [SD]: 0.09) at 9 years of age to 16.5 (SD: 2.65) nmol/L at 17 years of age; these values are congruent with other reports in the literature. The average exposure to testosterone is associated with different features of testosterone trajectories such as Peak Testosterone Change, Age at Peak Testosterone Change, and Testosterone at 17 years of age as well as the timing of the growth spurt during puberty.The average exposure to testosterone is a useful measure for future investigations using testosterone trajectories to examine pubertal dynamics