Health and Medical Physics Commons^™

Assessing The Practicality Of Using A Single Knowledge-Based Planning Model For Multiple Linac Vendors, Raphael J Douglas, Adenike Olanrewaju, Lifei Zhang, Beth M Beadle, Laurence E Court

Faculty, Staff and Student Publications

Purpose: Knowledge-based planning (KBP) has been shown to be an effective tool in quality control for intensity-modulated radiation therapy treatment planning and generating high-quality plans. Previous studies have evaluated its ability to create consistent plans across institutions and between planners within the same institution as well as its use as teaching tool for inexperienced planners. This study evaluates whether planning quality is consistent when using a KBP model to plan across different treatment machines.

Materials and methods: This study used a RapidPlan model (Varian Medical Systems) provided by the vendor, to which we added additional planning objectives, maximum dose limits, …

Adding Customized Electron Energy Beams To Truebeam Linear Accelerators, Song Gao, Manickam Muruganandham, Weiliang Du, Jared Ohrt, Rajat J Kudchadker, Peter A Balter

Faculty, Staff and Student Publications

Purpose: To better meet clinical needs and facilitate optimal treatment planning, we added two new electron energy beams (7 and 11 MeV) to two Varian TrueBeam linacs.

Methods: We worked with the vendor to create two additional customized electron energies without hardware modifications. For each beam, we set the bending magnet current and then optimized other beam-specific parameters to achieve depths of 50% ionization (I50 ) of 2.9 cm for 7 MeV and 4.2 cm for the 11 MeV beam with the 15 × 15 cm2 cone at 100 cm source-to-surface distance (SSD) by using an ionization chamber profiler (ICP) …

Predictive Performance Of Different Ntcp Techniques For Radiation-Induced Esophagitis In Nsclc Patients Receiving Proton Radiotherapy, Mei Chen, Zeming Wang, Shengpeng Jiang, Jian Sun, Li Wang, Narayan Sahoo, G Brandon Gunn, Steven J Frank, Cheng Xu, Jiayi Chen, Quynh-Nhu Nguyen, Joe Y Chang, Zhongxing Liao, X Ronald Zhu, Xiaodong Zhang

Faculty, Staff and Student Publications

This study aimed to compare the predictive performance of different modeling methods in developing normal tissue complication probability (NTCP) models for predicting radiation-induced esophagitis (RE) in non-small cell lung cancer (NSCLC) patients receiving proton radiotherapy. The dataset was composed of 328 NSCLC patients receiving passive-scattering proton therapy and 41.6% of the patients experienced ≥ grade 2 RE. Five modeling methods were used to build NTCP models: standard Lyman-Kutcher-Burman (sLKB), generalized LKB (gLKB), multivariable logistic regression using two variable selection procedures-stepwise forward selection (Stepwise-MLR), and least absolute shrinkage and selection operator (LASSO-MLR), and support vector machines (SVM). Predictive performance was internally …

A Roadmap To Clinical Trials For Flash, Paige A Taylor, Jean M Moran, David A Jaffray, Jeffrey C Buchsbaum

Faculty, Staff and Student Publications

While FLASH radiation therapy is inspiring enthusiasm to transform the field, it is neither new nor well understood with respect to the radiobiological mechanisms. As FLASH clinical trials are designed, it will be important to ensure we can deliver dose consistently and safely to every patient. Much like hyperthermia and proton therapy, FLASH is a promising new technology that will be complex to implement in the clinic and similarly will require customized credentialing for multi-institutional clinical trials. There is no doubt that FLASH seems promising, but many technologies that we take for granted in conventional radiation oncology, such as rigorous …

Knowledge-Based Planning For The Radiation Therapy Treatment Plan Quality Assurance For Patients With Head And Neck Cancer, Wenhua Cao, Mary Gronberg, Adenike Olanrewaju, Thomas Whitaker, Karen Hoffman, Carlos Cardenas, Adam Garden, Heath Skinner, Beth Beadle, Laurence Court

Faculty, Staff and Student Publications

This study aimed to investigate the feasibility of using a knowledge-based planning technique to detect poor quality VMAT plans for patients with head and neck cancer. We created two dose-volume histogram (DVH) prediction models using a commercial knowledge-based planning system (RapidPlan, Varian Medical Systems, Palo Alto, CA) from plans generated by manual planning (MP) and automated planning (AP) approaches. DVHs were predicted for evaluation cohort 1 (EC1) of 25 patients and compared with achieved DVHs of MP and AP plans to evaluate prediction accuracy. Additionally, we predicted DVHs for evaluation cohort 2 (EC2) of 25 patients for which we intentionally …

Effect Of Perfluorocarbon Composition On Activation Of Phase-Changing Ultrasound Contrast Agents, Trevor M Mitcham, Dmitry Nevozhay, Yunyun Chen, Linh D Nguyen, Gianmarco F Pinton, Stephen Y Lai, Konstantin V Sokolov, Richard R Bouchard

Faculty, Staff and Student Publications

BACKGROUND: While microbubble contrast agents (MCAs) are commonly used in ultrasound (US), they are inherently limited to vascular targets due to their size. Alternatively, phase-changing nanodroplet contrast agents (PNCAs) can be delivered as nanoscale agents (i.e., small enough to extravasate), but when exposed to a US field of sufficient mechanical index (MI), they convert to MCAs, which can be visualized with high contrast using nonlinear US.

PURPOSE: To investigate the effect of perfluorocarbon (PFC) core composition and presence of cholesterol in particle coatings on stability and image contrast generated from acoustic activation of PNCAs using high-frequency US suitable for clinical …

An Efficient Magnetic Resonance Image Data Quality Screening Dashboard, Evan D H Gates, Adrian Celaya, Dima Suki, Dawid Schellingerhout, David Fuentes

Faculty, Staff and Student Publications

Purpose: Complex data processing and curation for artificial intelligence applications rely on high-quality data sets for training and analysis. Manually reviewing images and their associated annotations is a very laborious task and existing quality control tools for data review are generally limited to raw images only. The purpose of this work was to develop an imaging informatics dashboard for the easy and fast review of processed magnetic resonance (MR) imaging data sets; we demonstrated its ability in a large-scale data review.

Methods: We developed a custom R Shiny dashboard that displays key static snapshots of each imaging study and its …

Brain Stereotactic Radiosurgery Using Mr-Guided Online Adaptive Planning For Daily Setup Variation: An End-To-End Test, Eun Young Han, He Wang, Tina Marie Briere, Debra Nana Yeboa, Themistoklis Boursianis, Georgios Kalaitzakis, Evangelos Pappas, Pamela Castillo, Jinzhong Yang

Faculty, Staff and Student Publications

Online magnetic resonance (MR)-guided radiotherapy is expected to benefit brain stereotactic radiosurgery (SRS) due to superior soft tissue contrast and capability of daily adaptive planning. The purpose of this study was to investigate daily adaptive plan quality with setup variations and to perform an end-to-end test for brain SRS with multiple metastases treated with a 1.5-Tesla MR-Linac (MRL). The RTsafe PseudoPatient Prime brain phantom was used with a delineation insert that includes two predefined structures mimicking gadolinium contrast-enhanced brain lesions. Daily adaptive plans were generated using six preset and six random setup variations. Two adaptive plans per daily MR image …

A Retrospective Dosimetry Comparison To Define Uncertainties Found In A Novel Intensity Modulated Electron Therapy (Imet) Treatment Technique For Use In Radiation Therapy, Marco A. Masciantonio

Honors Undergraduate Theses

This study will investigate the difference in radiation at different volumes between traditional electron beam therapy and a novel IMET. The difference in dose will be recorded between the novel IMET and the IMET with a slight shift in the target area. The percent difference between this new model treatment and the model treatment with a shift will be calculated. The main goal of this project is to determine if the target area is still sufficiently treated with this slight shift of the patient in different directions. The percent difference is crucial for the success of this project. It will …

A Game Theoretical Model Of Radiological Terrorism Defense, Shraddha Rane, Jason Timothy Harris

International Journal of Nuclear Security

Radiological dispersal devices (RDD) pose a threat to the United States. Healthcare facilities housing high-risk radioactive materials and devices are potentially easy targets for unauthorized access and are vulnerable to malevolent acts of theft or sabotage. The three most attractive candidates for use in RDD considered in this study are: ⁶⁰Co (radiosurgery devices), ¹³⁷Cs (blood irradiators) and ¹⁹²Ir (brachytherapy high dose radiation device). The threat posed by RDDs has led to evaluating the security risk of radioactive materials and defending against attacks. The concepts of risk analysis used in conjunction with game theory lay the foundations of …

Nuclear Security Awareness Survey At A University, Marcia P. Robinson, Naomi German, Destiny B. White, Shraddha V. Rane, Jason Timothy Harris

International Journal of Nuclear Security

The concept of assessing safety culture in an organization emerged with its application at the nuclear power industry and has expanded since then. An assessment of nuclear security, on the contrary, is still under-developed, especially at non-nuclear facilities, such as academic institutions and medical facilities. To identify the level of the awareness and understanding of credible nuclear and radiological threats, response preparedness, security culture, and the integrity of nuclear security systems among non-radioactive material users at a university setting; a campus-wide survey was deployed. A total of 3,336 non-radioactive material users, including students, faculty, and staff participated in the survey. …

Investigating The Uncertainties In Ct Non-Small Cell Lung Cancer Radiomics, Gary Ge

Theses and Dissertations--Radiation Medicine

Radiomics is a technique that extracts quantitative features, termed radiomic features, from medical images using data-characterization algorithms. These radiomic features can be used to identify tissue characteristics and radiologic phenotyping that are not observable by clinicians in a non-invasive, low-cost manner, potentially generating image biomarkers for clinical decision. To date, there are still many uncertainties involved in radiomics which limit its clinical implementation. Herein, we propose to explore the impact of each component in the radiomics pipeline on predicting clinical outcomes. In Chapter II, we conduct a thorough review of CT lung cancer radiomics studies to examine the typical feature …

The Yearly Financing Need Of Providing Paid Maternity Leave In The Informal Sector In Indonesia, Adiatma Y. M. Siregar, Pipit Pitriyan, Donny Hardiawan, Paul Zambrano, Mireya Vilar-Compte, Graciela Ma Teruel Belismelis, Meztli Moncada, David Tamayo, Grace Carroll, Rafael Perez-Escamilla, Roger Mathisen

Department of Public Health Scholarship and Creative Works

Background: The economic cost of not breastfeeding in Indonesia is estimated at US$1.5–9.4 billion annually, the highest in South East Asia. Half of the 33.6 million working women of reproductive age (WRA) in Indonesia (15–49 years) are informal employees, meaning they are working as casual workers or they are self-employed (small scale business) and assisted by unpaid/family worker(s). No specific maternity protection entitlements are currently available for WRA working informally in Indonesia. This study aims to estimate the financing need of providing maternity leave cash transfer (MCT) for WRA working in the informal sector in Indonesia. Method: The costing methodology …

Breastfeeding Media Coverage And Beliefs During The Covid-19 Pandemic In Mexico: Implications For Breastfeeding Equity, Mireya Vilar-Compte, P. Gaitán‐Rossi, E. C. Rhodes, V. Cruz‐Villalba, R. Pérez‐Escamilla

Department of Public Health Scholarship and Creative Works

Background: Because breastfeeding offers short- and long- term health benefits to mothers and children, breastfeeding promotion and support is a public health priority. Evidence shows that SARS-CoV-2 is not likely to be transmitted via breastmilk. Moreover, antibodies against SARS-CoV-2 are thought to be contained in breastmilk of mothers with history of COVID-19 infection or vaccination. WHO recommends direct breastfeeding as the preferred infant feeding option during the COVID-19 pandemic, even among women with COVID-19; but conflicting practices have been adopted, which could widen existing inequities in breastfeeding. This study aims to describe how information about breastfeeding was communicated in Mexican …

La Migración Como Determinante De La Obesidad Infantil En Estados Unidos Y Latinoamérica, Mireya Vilar-Compte, Arturo V. Bustamante, Nancy López-Olmedo, Pablo Gaitán-Ross, Jaqueline Torres, Karen E. Peterson, Graciela Teruel, Rafael Pérez-Escamilla

Department of Public Health Scholarship and Creative Works

La migración internacional tiene consecuencias económicas y en la salud. El proceso de aculturación en el país de acogida puede estar relacionado con la obesidad infan-til. Utilizamos el marco conceptual del balance energético comunitario (CEB, por sus siglas en inglés) para analizar la relación entre migración y obesidad infantil en los hogares mexicanos con migrantes internacionales. Utilizando datos longitudinales de la Encuesta Nacional de Niveles de Vida de los Hogares de México (ENNViH), exami-namos cómo influyen las redes de migrantes sobre la obesidad infantil en las comuni-dades de origen. También revisamos programas de salud binacionales que podrían ser eficaces para …

Living Environment Considerations On Obesity Prevention Behaviors And Self-Efficacy Among Chinese Americans, Doreen Liou, Jessica A. Karasik

Department of Nutrition and Food Studies Scholarship and Creative Works

The aim of this study is to ascertain if the living environment (type of residential neighborhood and number of household members) will elucidate differences in obesity risk reduction behaviors and self-efficacy in Chinese Americans. A cross-sectional survey design was used to recruit participants from Los Angeles County and New York City metropolitan areas. A total of 650 adults were recruited from diverse socioeconomic backgrounds. Descriptive statistics were measured for 19 behaviors reflecting food intake and portion size control and items measuring self-efficacy and attitudes. T-tests were applied for the two categories of living environment. The mean age of the sample …

Modeling Of Island Block Scatter For Intensity Modulated Bolus Electron Conformal Therapy, Joseph G. Scotto

LSU Master's Theses

Purpose: Bolus electron conformal therapy (BECT) benefits treatment of the post-mastectomy chest wall, head and neck, paraspinal muscles, and extremities. Patient dose heterogeneities caused by bolus can be reduced through intensity modulation (IM) across the incident electron beam. This requires passive radiotherapy intensity modulation for electrons (PRIME) devices, which utilize tungsten pins (island blocks) imbedded in machinable foam. IM-BECT treatment planning requires accurate dose calculation using the pencil beam redefinition dose algorithm (PBRA). Currently, the PBRA models island blocks as perfect collimators. This work explores models to account for electrons scattering into and out of the sides of island blocks. …

Migration As A Determinant Of Childhood Obesity In The United States And Latin America, Mireya Vilar-Compte, Arturo V. Bustamante, Nancy López-Olmedo, Pablo Gaitán-Rossi, Jaqueline Torres, Karen E. Peterson, Graciela Teruel, Rafael Pérez-Escamilla

Department of Public Health Scholarship and Creative Works

International migration has economic and health implications. The acculturation process to the host country may be linked to childhood obesity. We use the Community Energy Balance (CEB) framework to analyze the relationship between migration and childhood obesity in Mexican households with international migrants. Using longitudinal data from the Mexican Family Life Survey (MxFLS), we examine how migrant networks affect childhood obesity in origin communities. We also review binational health programs that could be effective at tackling childhood obesity in migrant households from Mexico. Children embedded in migrant networks are at greater risk of developing overweight or obesity, suggesting a significant …

Implementation Of Childhood Obesity Prevention And Control Policies In The United States And Latin America: Lessons For Cross-Border Research And Practice, Rafael Perez-Escamilla, Mireya Vilar-Compte, Elizabeth Rhodes, Olga L. Sarmiento, Camila Corvalan, Rachel Sturke, Susan Vorkoper

Department of Public Health Scholarship and Creative Works

Progress has been made in the development and widespread implementation of effective interventions to address childhood obesity, yet important challenges remain. To understand how the United States and Latin American countries achieved success in implementing obesity policies and programs (PAPs) and identify improvement opportunities using implementation science principles. We identified three comparative case studies: (1) front-of-food package labeling (Mexico and Chile); (2) Open Streets/play streets (Colombia and the United States); and (3) the Baby-Friendly Hospital Initiative (Brazil and the United States). Information from multiple sources (e.g., scientific and gray literature and key informant interviews) was synthesized to describe barriers, facilitators, …

The Financing Need For Expanding Paid Maternity Leave To Support Breastfeeding In The Informal Sector In The Philippines, Valerie Gilbert Ulep, Paul Zambrano, Janice Datu-Sanguyo, Mireya Vilar-Compte, Graciela Materuel Belismelis, Rafael Pérez-Escamilla, Grace J. Carrol, Roger Mathisen

Department of Public Health Scholarship and Creative Works

In low- and middle-income countries, almost three-fourths of women in the labour force lack maternity protection. In the Philippines, current laws do not guarantee paid maternity leave to workers in the informal economy. A non-contributory maternity cash transfer to informal sector workers could be used to promote social equity and economic productivity and could provide health benefits by helping mothers meet their breastfeeding goals. The objective of the study is to provide a realistic cost estimate and to assess the financial feasibility of implementing a publicly financed, non-contributory maternity cash transfer programme to the informal sector in the Philippines. Using …

Food Insecurity Measurement And Prevalence Estimates During The Covid-19 Pandemic In A Repeated Cross-Sectional Survey In Mexico, Pablo Gaitán-Rossi, Mireya Vilar-Compte, Graciela Teruel, Rafael Pérez-Escamilla

Department of Public Health Scholarship and Creative Works

Objective: To validate the telephone modality of the Latin American and Caribbean Food Security Scale (ELCSA) included in three waves of a phone survey to estimate the monthly household food insecurity prevalence during the COVID-19 pandemic in Mexico. Design: We examined the reliability and internal validity of the ELCSA scale in three repeated waves of cross-sectional surveys with Rasch models. We estimated the monthly prevalence of food insecurity in the general population and in households with and without children and compared them with a national 2018 survey. We tested concurrent validity by testing associations of food insecurity with socio-economic status …

Leakage Versus Material Filtration In Barrier Facemask Efficiency, Ali Bahloul, Clothilde Brochot, Barbara Layne

Études primaires

The World Health Association and many governmental agencies recommend the wearing of facemasks by the general public to prevent the spread of COVID-19. It is believed that masks can significantly protect others and may offer some protection to the wearer. Although there are standards for FFRs, surgical masks, and recently for barrier face coverings, they all indicate the level of protection for the wearer. However, testing facial masks not at the point of inhalation, but at the source, the exhale, offers a new perspective on how to impede particle emissions. In this paper, the experimental results show that, although the …

A Deep Learning U-Net For Detecting And Segmenting Liver Tumors, Vidhya Cardozo

Theses and Dissertations

Visualization of liver tumors on simulation CT scans is challenging even with contrast-enhancement, due to the sensitivity of the contrast enhancement to the timing of the CT acquisition. Image registration to magnetic resonance imaging (MRI) can be helpful for delineation, but differences in patient position, liver shape and volume, and the lack of anatomical landmarks between the two image sets makes the task difficult. This study develops a U-Net based neural network for automated liver and tumor segmentation for purposes of radiotherapy treatment planning. Non-contrast simulation based abdominal CT axial scans of 52 patients with primary liver tumors were utilized. …

How Effective Is The Filtration Of ‘Kn95’ Filtering Facepiece Respirators During The Covid-19 Pandemic?, Clothilde Brochot, Mohamed Nejib Saidi, Ali Bahloul

Études primaires

Objectives

The high demand of filtering facepiece respirators (FFRs) worldwide during the period of the COVID-19 pandemic has led to a critical situation for decision-makers regarding their supply. After authorizing the use of FFRs certified by other regions of the world, decision-makers in many countries have published alerts, particularly concerning the ‘KN95’ type.

Methods

This paper investigated the filtration performance of different FFRs using an experimental setup already employed during several studies on FFRs filtration performance. Its high-resolution measuring devices permit to determine filtration performance according to the normative criteria: the pressure drop and the filtration efficiency. Eight different FFRs …

Non-Traditional Component Of Metabolic Syndrome In Children With Obesity: Assesment Of Tg:Hdl-C Ratio As Insulin Resistance Component, Nur Zati Iwani Ahmad Kamil

Student Works (2020-2029)

Paediatrics metabolic syndrome (MetS) is on the rise parallel to the increased prevalence of childhood obesity. Although insulin resistance (IR) is an important variable in the diagnosis of MetS, the existing paediatric definition of MetS only measures elevated fasting blood glucose (FBG). Arguably, many children with severe IR can still regulate their FBG, especially in children with obesity. Therefore, this study aims to assess the utility of triglyceride to high-density lipoprotein-cholesterol (TG: HDL-C) ratio as an IR marker in the modelling of paediatric MetS among children with obesity using structural equation modelling (SEM). This is a cross-sectional study in which …

How Much Can Mexican Healthcare Providers Learn About Breastfeeding Through A Semi-Virtual Training? A Propensity Score Matching Analysis, Mireya Vilar-Compte, Rafael Pérez-Escamilla, Meztli Moncada, Diana Flores

Department of Public Health Scholarship and Creative Works

Background: Mexico has shown a worrisome decrease in breastfeeding indicators, especially in the lowest socioeconomic level. Improving breastfeeding protection, promotion, and support services through workforce development is a key area of intervention. The objective of this study is to assess the influence on breastfeeding knowledge and abilities of a semi-virtual training for primary healthcare providers assisting beneficiaries of PROSPERA in Mexico, which is one of the largest conditional cash-transfer programs in the world. Methods: Two independent cross-sectional samples of healthcare providers were drawn at baseline and post-intervention in three states of Mexico. Baseline data were collected among primary physicians, registered …

Reconsidering The Obstetrical Dilemma: Correlations Between Head And Pelvic Size, Kelsey Catrice Fox

LSU Master's Theses

The Obstetrical Dilemma (OD) theory has become canon in biological anthropology. The OD posits that i] dystocia results from bipedal mothers and encephalized infants, ii] contrasting selection for bipedality and obstetrics hinders locomotive efficiency, and iii] the contradicting requirement of the fetus being small enough to pass through the birth canal yet being cognitively advanced enough to cling to its mother after birth. Females, theoretically, exhibit deficient gait efficiency for the sake of successful childbirth. An obstetric advantage theory has been posited where taller individuals with a larger head size have larger pelves. If the distance between the acetabulae increases …

Costs Of Maternity Leave To Support Breastfeeding; Brazil, Ghana And Mexico, Mireya Vilar-Compte, Graciela M. Teruel, Diana Flores-Peregrina, Grace J. Carroll, Gabriela S. Buccini, Rafael Perez-Escamilla

Department of Public Health Scholarship and Creative Works

Objective To develop a method to assess the cost of extending the duration of maternity leave for formally-employed women at the national level and apply it in Brazil, Ghana and Mexico. Methods We adapted a World Bank costing method into a five-step method to estimate the costs of extending the length of maternity leave mandates. Our method used the unit cost of maternity leave based on working women’s weekly wages; the number of additional weeks of maternity leave to be analysed for a given year; and the weighted population of women of reproductive and legal working age in a given …

Towards Optimizing Quality Assurance Outcomes Of Knowledge-Based Radiation Therapy Treatment Plans Using Machine Learning, Phillip Douglas Hardenbergh Wall

LSU Doctoral Dissertations

Knowledge-based planning (KBP) techniques have been shown to provide improvements in plan quality, consistency, and efficiency for advanced radiation therapies such as volumetric modulated arc therapy (VMAT). While the potential clinical benefits of KBP methods are generally well known, comparatively less is understood regarding the impact of using these systems on resulting plan complexity and pre-treatment quality assurance (QA) measurements, especially for in-house KBP systems. Therefore, the overarching purpose of this work was to assess QA implications with using an in-house KBP system and explore data-driven methods for mitigating increased plan complexity and QA error rates without compromising dosimetric plan …

Costing Of Actions To Safeguard Vulnerable Mexican Households With Young Children From The Consequences Of Covid-19 Social Distancing Measures, Mireya Vilar-Compte, Víctor Pérez, Graciela Teruel, Aranzazu Alonso, Rafael Pérez-Escamilla

Department of Public Health Scholarship and Creative Works

COVID-19 has imposed unprecedented challenges to society. As the pandemic evolves, the social distancing measures that have been globally enforced, while essential, are having undesirable socioeconomic side effects particularly among vulnerable populations. In Mexico, families who depend upon informal employment face increased threats to their wellbeing, and households who in addition have young children may face long-term consequences. The Mexican government has not yet taken actions, but a coalition of non-governmental organizations is advocating in partnership with academic institutions for social protection actions such as a cash transfer and basic services subsidies for families with young children, subsisting from the …