Health and Medical Physics Commons^™

Comparison Of Signaling Profiles In The Low Dose Range Following Low And High Let Radiation, Deepa M. Sridharan, Lung-Chang Chien, Francis A. Cucinotta, Janice M. Pluth

Environmental & Global Health Faculty Research

During space travel astronauts will be exposed to a very low, mixed field of radiation containing different high LET particles of varying energies, over an extended period. Thus, defining how human cells respond to these complex low dose exposures is important in ascertaining risk. In the current study, we have chosen to investigate how low doses of three different ion's at various energies uniquely change the kinetics of three different phospho-proteins. A normal hTERT immortalized fibroblast cell line, 82–6, was exposed to a range of lower doses (0.05–0.5 Gy) of radiation of different qualities and energies (Si 1000 MeV/u, Si …

Development Of A Diabetes Self-Management + Mhealth Program: Tailoring The Intervention For A Pilot Study In A Low-Income Setting In Mexico, Robin Whittemore, Mireya Vilar-Compte, Soraya Burrola-Méndez, Annel Lozano-Marrufo, Roberta Delvy, Mariana Pardo-Carrillo, Selene De La Cerda, Ninfa Pena-Purcell, Rafael Pérez-Escamilla

Department of Public Health Scholarship and Creative Works

Background: Type 2 diabetes (T2D) is a public health pandemic disproportionately affecting low- and middle-income countries. The purpose of this formative research was to adapt evidence-based diabetes self-management education programs to the context of Seguro Popular clinics in Mexico. A theory-based mHealth (pictorial text messaging) component was developed.

Method: Our formative research and development of the program protocol consisted of six phases: (1) interviews and focus groups with stakeholders on the challenges to T2D management, curriculum content needs, and the use of mHealth as a supplement to a DSME program; (2) review of the theoretical underpinning, curriculum, and interactive strategies …

Association Between Breastfeeding And Child Stunting In Mexico, Ana Paola Campos, Mireya Vilar-Compte, Summer Sherburne Hawkins

Department of Public Health Scholarship and Creative Works

Background: Globally, the prevalence of child stunting has been decreasing over the past decades. How-ever, in low-and middle-income countries such as Mexico, stunting is still the most prevalent form of undernutrition affecting a large number of children in the most vulnerable conditions. Breastfeeding has been identified as one of the key affordable and modifiable maternal health behaviors protecting against child stunting. Objective: To examine the association between breastfeeding (defined as never breastfed, any breast-feeding for <6 months, and any breastfeeding for ≥6 months) and other individual-, household-, and area-level factors with child stunting (defined as length/height-for-age-z-score for sex under –2 standard deviations of the World Health Organization child growth standards’ median) in Mexico. Methods: Secondary data analysis using the 2012 Mexican Health and Nutrition Survey, which allowed representativeness of rural and urban areas at national level and among 4 regions in Mexico. Our subset included data on 2,089 singleton Mexican children aged 6–35 months with information on previously identified risk and protective factors for stunting. We conducted fixed-and mixed-effects logistic regression models sequentially controlling for each level of factors. Findings: Overall, 12.3% of children were stunted and 71.1% were breastfed for ≥6 months. Any breast-feeding and being female were consistent protective factors against child stunting across all models. In contrast, child low birthweight, maternal short stature, higher number of children aged <5 years per household, and moderate to severe food insecurity were consistent risk factors for child stunting across all models. Conclusions: According to our findings, efforts to reduce child stunting in Mexico should include prenatal strategies aiming to prevent low birthweight offspring particularly among short-stature women, moderate to severe food insecure households, families with a higher number of children aged <5 years, and indigenous communities. Postnatal components should include multilevel strategies to support breastfeeding.

Performance Of Mechanical Filters Used In General Ventilation Against Nanoparticles, Clothilde Brochot, Pooya Abdolghader, Fariborz Haghighat, Ali Bahloul

Études primaires

With an equal mass, nanoparticles (NP) have a higher toxicity than particles with the same chemical composition but with larger surface area. However, the toxicological knowledge concerning NP is still insufficient to establish limit values of exposure. To seek the lowest exposure level, filtration is a simple and effective way to capture particles, including NP. According to ANSI/ASHRAE 52.2 standard, ventilation filters efficiency is tested for particles ranging from 0.3 to 10.0 μm. Performances of entire filters for NP are still very limited and particle size of 300 nm (0.3 μm) is commonly used as the most penetrating particle size …

Qualitative Knowledge Of Filtering Facepiece Respirators For Filtration Performance Tests During The Covid-19 Pandemic, Clothilde Brochot, Mohamed Nejib Saidi, Ali Bahloul

Études primaires

Background: During the COVID-19 pandemic, the pressure on health centers to obtain certified N95 filtering facepiece respirators (N95 FFRs) and the pressure on the FFRs production sector led to a diversification of FFRs’ supply chains, with the approval of several government authorities.

Objective: The main issue then becomes whether these purchased FFRs are as effective as the FFRs commonly used in the pre-COVID-19 period.

Methods: The most efficient way is to test these FFRs under normative conditions. The setup used here allows to measure the pressure drop Δp (mbar) and the filtration efficiency E (%) of FFRs with a constant …

Theoretical Investigation Of The Low Frequency Fundamental Mechanism Of The Objective Occlusion Effect Induced By Bone-Conducted Stimulation, Kevin Carillo, Olivier Doutres, Franck Sgard

Études primaires

The objective occlusion effect induced by bone-conducted stimulation refers to the low frequency acoustic pressure increase that results from occluding the ear canal opening. This phenomenon is commonly interpreted as follows: the bone-conducted sound “leaks” through the earcanal opening and is “trapped” by the occlusion device. This instinctive interpretation misrepresents the fundamental mechanism of the occlusion effect related to the earcanal impedance increase and already highlighted by existing electro-acoustic models. However, these models simplify the earcanal wall vibration (i.e., the origin of the phenomenon) to a volume velocity source which, in the authors' opinion, (i) hinders an exhaustive comprehension of …

Comparative Performance Of The Nanoscan And The Classic Smps In Determining N95 Filtering Facepiece Efficiency Against Nanoparticles, Clothilde Brochot, Fariborz Haghighat, Ali Bahloul

Études primaires

Nanoparticles are defined as particles with at least one dimension in the range of 1–100 nm. Due to the special properties of nanoparticles, they are used in many workplaces, thus leading to occupational exposure. Filtering facepieces (FFPs) are generally used in these workplaces to reduce the exposure. Many studies have measured FFP efficiency in laboratories using a scanning mobility particle sizer (SMPS). The aim of this study was to determine whether a NanoScan could be used to measure FFP efficiency against nanoparticles in workplaces for one type of N95 FFP. The results showed that the NanoScan gave maximum penetration and …

Quantitative Study Of The Antimicrobial Effects Of Silver On The Motility Of Escherichia Coli, Benjamin Russell

Graduate Theses and Dissertations

In recent decades, the number of antibiotic-resistant bacterial infections has grown to become a serious global threat. This rise can be attributed to the widespread misuse of antibiotics and the lack of newly developed drugs to fight resistant organisms. Novel bactericidal substances have, therefore, garnered significant research interest. Silver, due to its powerful antimicrobial effects, is one such substance. Silver is typically most effective in cationic form; however, advancements in nanotechnology have paved the way for the controlled fabrication of nano-silver. Silver nanoparticles have been shown to have increased antibacterial potency for a variety of reasons, including the release of …

Evaluating Feline Release Criteria Following Iodine-131 Therapy For Hyperthyroidism, Anthony Davila

LSU Master's Theses

Hyperthyroidism is a very common endocrine disorder in both humans and cats. Radioactive iodine ablation therapy is considered the gold standard; however, the patient becomes a radiation source and poses a potential radiological risk to others. The regulations governing when the patient can be released differ between human medicine and veterinary medicine. A human patient can receive up to 33 mCi of I-131 and be discharged the same day; yet a feline patient can receive a dose as low as 2 mCi and require multiple days of hospitalization. This discrepancy has not been satisfactorily addressed; and overly restrictive release criteria …

Challenges To Diabetes Self-Management For Adults With Type 2 Diabetes In Low-Resource Settings In Mexico City: A Qualitative Descriptive Study, Robin Whittemore, Mireya Vilar-Compte, Selene De La Cerda, Denise Marron, Rosabelle Conover, Roberta Delvy, Annel Lozano-Marrufo, Rafael Pérez-Escamilla

Department of Public Health Scholarship and Creative Works

Background: The prevalence of type 2 diabetes (T2D) in Mexico is one of the highest in the world, with high morbidity and mortality, and difficulty meeting glycemic targets. The purpose of this study was to identify the challenges for T2D self-management as perceived by both adults with T2D and health care providers in primary health clinics from Seguro Popular in Mexico City.

Methods: This was a qualitative descriptive study conducted in three Seguro Popular primary care clinics in Mexico City using convenience sampling. Semi-structured interviews were conducted with participants and data were analyzed using a content analysis approach.

Results: The …

Short Relative Leg Length Is Associated With Overweight And Obesity In Mexican Immigrant Women, Mireya Vilar-Compte, James Macinko, Beth C. Weitzman, Carlos M. Avendaño-Villela

Department of Public Health Scholarship and Creative Works

Background: Prior research suggests that undernutrition and enteric infections predispose children to stunted growth. Undernutrition and infections have been associated with limited access to healthy diets, lack of sanitation, and access barriers to healthcare - all associated with human rights. Stunting has also been documented to be a major determinant of subsequent obesity and non-communicable diseases. Short leg length relative to stature during adulthood seems to be a good proxy indicator tracking such barriers, and has been reported to be associated with adverse health effects during adulthood. Our objective was to examine the association between relative leg length (as measured …

Stray Radiation Dose From X-Ray And Proton Beam Radiation Therapies, Christopher William Schneider

LSU Doctoral Dissertations

The growing population of cancer survivors at risk of radiation induced side-effects is a public health concern. These side-effects include serious conditions such as second cancers, the majority of which occur outside of the primary treatment volume. Radiotherapy treatment planning systems systematically underestimate the dose to tissues out-of-field. Attempts to predict and reduce the risks of radiogenic side effects require accurate and personalized knowledge of the out-of-field radiation dose to patients. The long-term goal of this research is to provide clinical and research tools necessary to reduce the risk of radiotherapy side effects and improve the health outcomes of radiotherapy …

Computational Feasibility Of Simulating Whole-Organ Vascular Networks And Their Response To Injury, William Patrick Donahue

LSU Doctoral Dissertations

Healthy vasculature is critical to sustaining the function of normal tissues in the human body. Radiation therapy for cancer causes injury of the vasculature of non-cancerous tissues. These changes have been associated with potentially deadly conditions such as necrosis of the brain tissue. There are currently no computational methods to study the effects of radiation vascular injury in whole-organ vasculatures because of the large number of vessels involved. The goal of this work was to test the feasibility of simulating radiation damage to whole-brain vascular networks and calculate the resulting change in blood flow. To accomplish this, we developed algorithms …

Determination Of Scatter Fractions, Albedos, And Tenth Value Layers For Shielding Of Synchrotron Beamline Hutches, Bethany Lynn Broekhoven

LSU Master's Theses

Synchrotron facilities require substantial amounts of shielding to protect facility staff and researchers. To meet mandatory exposure limits, the traditional combination of time, distance, and shielding of the radiation source are utilized. Because of continuous 24-7 operation of most synchrotrons, time is the least useful tool. The experimental stations for synchrotron x-ray beamlines, called hutches, enforce a minimum distance from the source, but shielding provided by hutch walls is still the principal tool for a synchrotron facility. Currently there is no single resource for synchrotron beamline hutch shielding design in the literature; most hutch shielding is designed through either over-simplified …

Sub-Region Based Radiomics Analysis For Survival Prediction In Oesophageal Tumours Treated By Definitive Concurrent Chemoradiotherapy, Congying Xie, Pengfei Yang, Xuebang Zhang, Lei Xu, Xiaoju Wang, Xiadong Li, Luhan Zhang, Ruifei Xie, Ling Yang, Zhao Jing, Hongfang Zhang, Lingyu Ding, Yu Kuang, Tianye Niu, Shixiu Wu

Health Physics and Diagnostic Sciences Faculty Research

Background: Evaluating clinical outcome prior to concurrent chemoradiotherapy remains challenging for oesophageal squamous cell carcinoma (OSCC) as traditional prognostic markers are assessed at the completion of treatment. Herein, we investigated the potential of using sub-region radiomics as a novel tumour biomarker in predicting overall survival of OSCC patients treated by concurrent chemoradiotherapy. Methods: Independent patient cohorts from two hospitals were included for training (n = 87) and validation (n = 46). Radiomics features were extracted from sub-regions clustered from patients' tumour regions using K-means method. The LASSO regression for ‘Cox’ method was used for feature selection. The survival prediction model …

Framework For Algorithmically Optimizing Longitudinal Health Outcomes: Examples In Cancer Radiotherapy And Occupational Radiation Protection, Lydia Joyce Wilson

LSU Doctoral Dissertations

Background: Advancements in the treatment of non-infectious disease have enabled survival rates to steadily increase in recent decades (e.g., diabetes, heart disease, and cancer). Epidemiological studies have revealed that the treatments for these diseases can have life-threatening and/or life–altering effects. Thus, realizing the full beneficial potential of advanced treatments necessitates new tools to algorithmically consider all major components of the health outcome, including benefit and detriment. The goal of this dissertation was to develop a framework for improving projected health outcomes following planned radiation exposures in consideration of all beneficial and detrimental, early and late, and fatal and non-fatal …

Potential Reduction Of Lung Dose Via Vmat With Jaw Tracking In The Treatment Of Single-Isocenter/Two-Lesion Lung Sbrt, Damodar Pokhrel, Lana Sanford, Matthew Halfman, Janelle A. Molloy

Radiation Medicine Faculty Publications

Purpose/objectives: Due to higher radiosensitivity, non‐target normal tissue dose is a major concern in stereotactic body radiation therapy (SBRT) treatment. The aim of this report was to estimate the dosimetric impact, specifically the reduction of normal lung dose in the treatment of single‐isocenter/two‐lesion lung SBRT via volumetric modulated arc therapy with jaw tracking (JT‐VMAT).

Materials/methods: Twelve patients with two peripherally located early‐stage non‐small‐cell‐lung cancer (NSCLC) lung lesions underwent single‐isocenter highly conformal non‐coplanar JT‐VMAT SBRT treatment in our institution. The mean isocenter to tumors distance was 5.6 ± 1.9 (range 4.3–9.5) cm. The mean combined planning target volume (PTV) was 38.7 …

Feedforward And Feedback Signals In The Olfactory System, Srimoy Chakraborty

Graduate Theses and Dissertations

The conglomeration of myriad activities in neural systems often results in prominent oscillations. The primary goal of the research presented in this thesis was to study effects of sensory stimulus on the olfactory system of rats, focusing on the olfactory bulb (OB) and the anterior piriform cortex (aPC). Extracellular electrophysiological measurements revealed distinct frequency bands of oscillations in OB and aPC. However, how these oscillatory fluctuations help the animal to process sensory input is not clearly understood. Here we show high frequency oscillations in olfactory bulb carry feedforward signals to anterior piriform cortex whereas feedback from the aPC is predominantly …

An Evaluation Of The Supply And Demand Of Radiation Oncology Medical Physicists In The United States., Christine Marie Swanson

Electronic Theses and Dissertations

Background: This dissertation is a mixed methods evaluation of the radiation oncology medical physics workforce in the United States. Radiation oncology medical physicists serve a vital role in the safe treatment of patients with radiation therapy. While cancer incidence continues to rise, the pathways to board certification in radiation oncology medical physics continue to narrow causing a potential shortage of radiation oncology physicists in the United States. While there is no lack of data about the medical physics community it has scarcely been used to evaluate the current state of the workforce. In order to ensure patient safety, appropriate physics …

An Iterative Process For Training Design And Implementation Increased Health Workers' Knowledge For Taking Nutrition Behavior Change To Scale, Wendy Gonzalez, Anabelle Bonvecchio Arenas, Armando García-Guerra, Mireya Vilar-Compte, Alejandría Villa De La Vega, Laura Quezada, Cynthia Rosas, Ana Lilia Lozada-Tequeanes, Amira Hernández

Department of Public Health Scholarship and Creative Works

The shortage of skilled, motivated, and well-supported health workers is a major barrier to scaling up nutrition interventions and services. Objective: The objective of this study is to describe the process for developing and implementing a training of health personnel for the delivery of the Integrated Strategy for Attention to Nutrition (EsIAN), an evidence-based strategy for promoting infant and young child feeding through primary health care in Mexico. The specific objective is to provide a case study and highlight challenges, as well as elements to successfully mitigate these, and discuss potential applications of findings beyond the Mexican context. Methods: The …

Evaluation Of Plan Quality And Treatment Efficiency For Single-Isocenter/Two-Lesion Lung Stereotactic Body Radiation Therapy, Lana Sanford, Janelle A. Molloy, Sameera S. Kumar, Marcus Randall, Ronald C. Mcgarry, Damodar Pokhrel

Radiation Medicine Faculty Publications

Purpose/objectives: To evaluate the plan quality and treatment delivery efficiency of single‐isocenter/two‐lesions volumetric modulated arc therapy (VMAT) lung stereotactic body radiation therapy (SBRT).

Materials/methods: Eight consecutive patients with two peripherally located early stage nonsmall‐cell‐lung cancer (NSCLC) lung lesions underwent single‐isocenter highly conformal noncoplanar VMAT SBRT treatment in our institution. A single‐isocenter was placed between the two lesions. Doses were 54 or 50 Gy in 3 and 5 fractions respectively. Patients were treated every other day. Plans were calculated in Eclipse with AcurosXB algorithm and normalized to at least 95% of the planning target volume (PTV) receiving 100% of the prescribed …

Classification Of Intensity-Modulated Proton Therapy Plans, Louise Gabrielle Lima '19, Alice Liu '19

Student Publications & Research

Proton Radiotherapy

Proton radiotherapy is a form of radiation treatment that uses energized protons to break DNA, leading to cell death and killing cancers.

Endorectal Digital Prostate Tomosynthesis, Joseph Robert Steiner

LSU Doctoral Dissertations

Several areas of prostate cancer (PCa) management, such as imaging permanent brachytherapy implants or small, aggressive lesions, benefit from high image resolution. Current PCa imaging methods can have inadequate resolution for imaging these areas. Endorectal digital prostate tomosynthesis (endoDPT), an imaging method that combines an external x-ray source and an endorectal x-ray sensor, can produce three-dimensional images of the prostate region that have high image resolution compared to typical methods. This high resolution may improve PCa management and increase positive outcomes in affected men.

This dissertation presents the initial development of endoDPT, including system design, image quality assessment, and examples …

Behavior Coding Strategies: Population Coupling And The Functional Role Of Excitatory/Inhibitory Balance In Primary Motor Cortex, Patrick Aaron Kells

Graduate Theses and Dissertations

The complexities of an organism’s experience of- and interaction with the world are emergent phenomena produced by large populations of neurons within the cerebral cortex and other brain regions. The network dynamics of these populations have been shown to be sometimes synchronous, with many neurons firing together, and sometimes asynchronous, with neurons firing more independently, leading to a decades-old debate within the neuroscience community. This discrepancy comes from viewing the system at two different scales; at the single cell level, the spiking activity of two neurons within cortex tend to be rather independent, but when the average activity of a …

Development And Applications Of A Real-Time Magnetic Electron Energy Spectrometer For Use With Medical Linear Accelerators, Paul Ethan Maggi

LSU Doctoral Dissertations

Purpose – This work presents a design for a real-time electron energy spectrometer, and provides data analysis methods and characterization of the real-time system. This system is intended for use with medical linear accelerators (linacs). The goal is 1 Hz acquisition of the energy range 4-25 MeV, reconstructed in 0.1 MeV increments.

Methods – Our spectrometer uses a nominal 0.54 T permanent magnet block as the dispersive element and scintillating fibers coupled to a CCD camera as the position sensitive detector. A broad electron beam produced by a linac is collimated by a 6.35 mm dimeter aperture at the entrance …

Proposed Method For Measuring The Let Of Radiotherapeutic Particle Beams, Stephen D. Bello

Physics & Astronomy ETDs

The Bragg peak geometry of the depth dose distributions for hadrons allows for precise and effective dose delivery to tumors while sparing neighboring healthy tissue. Further, compared against other forms of radiotherapeutic treatments, such as electron beam therapy (EBT) or photons (x and \(\gamma\)-rays), hadrons create denser ionization events along the particle track, which induces irreparable damage to DNA, and thus are more effective at inactivating cancerous cells. The measurement of radiation's ability to inactivate cellular reproduction is the relative biological effectiveness (RBE). A quality related to the RBE that is a measurable physical property is the linear energy transfer …

An Algorithm To Improve Deformable Image Registration Accuracy In Challenging Cases Of Locally-Advanced Non-Small Cell Lung Cancer, Christopher L. Guy

Theses and Dissertations

A common co-pathology of large lung tumors located near the central airways is collapse of portions of lung due to blockage of airflow by the tumor. Not only does the lung volume decrease as collapse occurs, but fluid from capillaries also fills the space no longer occupied by air, greatly altering tissue appearance. During radiotherapy, typically administered to the patient over multiple weeks, the tumor can dramatically shrink in response to the treatment, restoring airflow to the lung sections which were collapsed when therapy began. While return of normal lung function is a positive development, the change in anatomy presents …

Postural Responses To Perturbations Of The Vestibular System During Walking In Healthy Young And Older Adults, Jung Hung Chien

Theses & Dissertations

It has been shown that approximate one-third of US adults aged 40 years and older (69 million US citizens) have some type of vestibular problems. These declining abilities of the vestibular system affect quality of life. Difficulties in performing daily activities (dressing, bathing, getting in and out of the bed and etc.) have been highly correlated to loss of balance due to vestibular disorders. The exact number of people affected by vestibular disorders is still difficult to quantify. This might be because symptoms are difficult to describe and differences exist in the qualifying criteria within and across studies. Thus, it …

Multi – Modality Molecular Imaging Of Adoptive Immune Cell Therapy In Breast Cancer, Fatma Youniss

Theses and Dissertations

Cancer treatment by adoptive immune cell therapy (AIT) is a form of immunotherapy that relies on the in vitro activation and/or expansion of immune cells. In this approach, immune cells, particularly CD8+ T lymphocytes, can potentially be harvested from a tumor-bearing patient, then activated and/or expanded in vitro in the presence of cytokines and other growth factors, and then transferred back into the same patient to induce tumor regression. AIT allows the in vitro generation and activation of T-lymphocytes away from the immunosuppressive tumor microenvironment, thereby providing optimum conditions for potent anti-tumor activity. The overall objective of this study is …

Multimodality Molecular Imaging Of [18f]-Fluorinated Carboplatin Derivative Encapsulated In [111in]-Labeled Liposome, Narottam Lamichhane

Theses and Dissertations

Platinum based chemotherapy is amongst the mainstream DNA-damaging agents used in clinical cancer therapy today. Agents such as cisplatin, carboplatin are clinically prescribed for the treatment of solid tumors either as single agents, in combination, or as part of multi-modality treatment strategy. Despite the potent anti-tumor activity of these drugs, overall effectiveness is still hampered by inadequate delivery and retention of drug in tumor and unwanted normal tissue toxicity, induced by non-selective accumulation of drug in normal cells and tissues. Utilizing molecular imaging and nanoparticle technologies, this thesis aims to contribute to better understanding of how to improve the profile …