Health and Medical Physics Commons^™

Establishing A Comprehensive Framework For Sfrt Lattice Treatments: Optimization, Planning, And Clinical Evaluation, Gregory M. Gill

UNLV Theses, Dissertations, Professional Papers, and Capstones

Spatially fractionated radiation therapy (SFRT) using lattice radiotherapy (LRT) has emerged as a promising treatment technique for bulky, nonresectable tumors by delivering spatially heterogeneous dose distributions consisting of high-dose vertices embedded within lower-dose regions. Although early clinical experiences have demonstrated potential therapeutic benefit, widespread clinical implementation of LRT remains limited due to the absence of standardized treatment planning workflows, consistent optimization strategies, and clearly defined evaluation metrics for heterogeneous dose distributions. The objective of this study is to develop and evaluate a structured framework to support efficient, reproducible, and safe clinical implementation of LRT.

To address these challenges, a comprehensive …

Theory, Experiments, And Image Recovery Algorithms For X-Ray Interferometry, Hunter C. Meyer

LSU Doctoral Dissertations

Purpose: X-ray grating interferometry is a form of X-ray phase contrast imaging capable of simultaneously measuring attenuation, differential-phase, and dark-field images arising from X-ray absorption, refraction, and small-angle scattering, respectively. These additional contrast mechanisms have potential clinical and industrial applications, particularly for lung tissue characterization and disease identification. As grating interferometers approach clinical viability, key challenges include reducing X-ray dose, mitigating mechanical instability, and correcting spectral artifacts resulting from beam hardening.

Methods: The modulated phase grating interferometer (MPGI) is a potential solution for reducing X-ray dose by eliminating the analyzer grating used in alternative interferometer designs, including the Talbot-Lau interferometer …

Exploring The Impact Of Adverse Childhood Experiences On Preventive Healthcare Utilization In Rural Georgia, Ryan R. Traylor

College of Graduate Studies: Theses & Dissertations

This study examines the relationship between Adverse Childhood Experiences (ACEs) and preventive healthcare use among adults in Georgia, specifically within rural populations facing structural barriers. Using 2023 Georgia Behavioral Risk Factor Surveillance System (BRFSS) data, the research analyzes associations between ACE exposure, rural residence, and preventive care outcomes, including physical exams and flu vaccinations. Guided by an intersectionally adapted version of Andersen’s Behavioral Model of Health Services Use, the study evaluates how predisposing factors, enabling resources, and perceived barriers relate to healthcare engagement. Logistic regression analyses assess the correlation of ACE exposure, cost barriers, provider access, and sociodemographics with preventive …

A Framework For Digital Energy Modulation And Translation In Projectional X-Ray Imaging, Richard R. Wargo

Theses and Dissertations

In projectional X-ray imaging, acquisition energy fundamentally influences subject contrast, image noise, and radiation dose. While dual-energy techniques exploit spectral differences to optimize contrast and enable material separation, acquiring multiple images of the same anatomy often requires additional exposures and increased system complexity.

This dissertation presents a framework for digital energy modulation (DEM), in which computational models are trained to translate projection images between energy domains without requiring additional X-ray acquisitions. DEM is conceived as a generalizable strategy for controlled contrast modulation in projection imaging, with potential applications in image optimization, radiation therapy alignment, and dual-energy applications.

The framework was …

Developing Reference Plans For Evaluating Global Clinical Trials Credentialing And Psqa Systems, Fre'etta M D Brooks, Mohammad Hussein, Jessica Lye, Christopher L Nelson, Nakamura Mitsuhiro, Mallory C Glenn, Patricia Diez, Rushil Patel, Maddison Shaw, Ileana Silvestre Patallo, Miriam Barry, Catharine H Clark, Joerg Lehmann, Stephen F Kry

Faculty, Staff and Student Publications

Purpose: To develop a practical framework for creating a diverse set of validated reference plans (varying in complexity) and implement a workflow to introduce beam modeling, calibration, and delivery errors into the reference cohort to test and compare various dosimetry audit methodologies.

Methods: Sixteen IMRT and VMAT reference plans were created, using RayStation software, for four phantom geometries based on established credentialing cases from participating Global Harmonization Group (GHG) members. These reference plans were first validated in a multi-ion-chamber phantom. Nine dosimetric errors (perturbations) were introduced into the plans by modifying beam model and/or delivery parameters (MLC-offset, MLC-transmission, leaf-tip-width, PDD, …

Hyalinization-Based Pathologic Response And Immune Infiltration Following Neoadjuvant Radiotherapy With Or Without Immune-Checkpoint Blockade In Localized Undifferentiated Pleomorphic Sarcoma, R S Traweek, M Zoghbi, R Lazcano, B M Cope, A J Bishop, A Farooqi, D Mitra, A K Yoder, B A Guadagnolo, D R Ingram, K Wani, D Shamsutdinova, A J Lazar, W-L Wang, C P Scally, E Z Keung, K E Torres, K K Hunt, R Ratan, J A Livingston, M S Nakazawa, D M Araujo, S Patel, V Ravi, A P Conley, M A Zarzour, N Somaiah, C L Roland, E F Nassif Haddad

Faculty, Staff and Student Publications

BACKGROUND: Standard-of-care treatment of localized undifferentiated pleomorphic sarcoma (UPS) involves preoperative radiotherapy (RT) and surgery. Combination of RT with immune-checkpoint blockade (ICB) represents a promising new strategy.

METHODS: Our primary objective was to assess survival outcomes and pathologically documented response in patients receiving RT with or without ICB or chemotherapy.

RESULTS: In a retrospective cohort of 68 patients with primary or locally recurrent UPS who received neoadjuvant RT with or without ICB, the ICB group had greater tumor hyalinization than the non-ICB group (89% compared with 30%, P = 0.018). In the non-ICB group, 19/37 patients (51%) achieved hyalinization-based pathologic …

Aapm Task Group No 249b-Essentials And Guidelines For Clinical Medical Physics Residency Training Programs, Jonathon A Nye, Joseph P Dugas, William D Erwin, David P Gierga, Darryl G Kaurin, Stephanie M Leon, Ho-Ling Anthony Liu, Zheng Feng Lu, Alphonso W Magri, Lynn N Rill, Leah K Schubert, Beth A Schueler, Irina Vergalasova, John Vetter, Brian D Wichman, Amy Shu-Jung Yu, Dandan Zheng

Faculty, Staff and Student Publications

The establishment of guidelines and curriculum standards for medical physics residency training is a critical component of setting expectations and competencies for the profession. Since the last publication of these standards, residency training has become integrated into the eligibility criteria for most medical physics certification bodies. The rapid growth of medical physics requires periodic review of the curriculum to remove outdated approaches, update established knowledge, and add emerging technologies. The goal of this document is to provide a reference standard for residency training program directors, training mentors, and residents to guide creation and/or optimization of their program's curriculum. The document …

Dose Prediction Via Deep Learning To Enhance Treatment Planning Of Lung Radiotherapy Including Simultaneous Integrated Boost Techniques, Wenhua Cao, Mary Gronberg, Stephen Bilton, Hana Baroudi, Skylar Gay, Christopher Peeler, Zhongxing Liao, Thomas J Whitaker, Karen Hoffman, Laurence E Court

Faculty, Staff and Student Publications

Background: Recent studies have shown deep learning techniques are able to predict three-dimensional (3D) dose distributions of radiotherapy treatment plans. However, their use in dose prediction for treatments with varied prescription doses including simultaneous integrated boost (SIB), that is, using multiple prescription doses within the same plan, and benefit in improving plan quality should be validated.

Purpose: To investigate the feasibility and potential benefit of using deep learning to predict dose distribution of volumetric modulated arc therapy (VMAT) including SIB techniques and improve treatment planning for patients with lung cancer.

Methods: The dose prediction model was trained with 93 retrospective …

T2-Weighted Imaging Of Rectal Cancer Using A 3d Fast Spin Echo Sequence With And Without Deep Learning Reconstruction: A Reader Study, Dan Nguyen, Sarah Palmquist, Ken-Pin Hwang, Jingfei Ma, Usama Salem, Jia Sun, Xinzeng Wang, Jong Bum Son, Randy Ernst, Peng Wei, Harmeet Kaur, Nir Stanietzky

Faculty, Staff and Student Publications

Purpose: To compare image quality and clinical utility of a T2-weighted (T2W) 3-dimensional (3D) fast spin echo (FSE) sequence using deep learning reconstruction (DLR) versus conventional reconstruction for rectal magnetic resonance imaging (MRI).

Methods: The study included 50 patients with rectal cancer who underwent rectal MRI consecutively between July 7, 2020 and January 20, 2021 using a T2W 3D FSE sequence with DLR and conventional reconstruction. Three radiologists reviewed the two sets of images, scoring overall SNR, motion artifacts, and overall image quality on a 3-point scale and indicating clinical preference for DLR or conventional reconstruction based on those three …

Robust Automated Method Of Spatial Resolution Measurement In Radiotherapy Ct Simulation Images, Pavel Govyadinov, Rick R Layman, Tucker Netherton, Raymond Mumme, Aaron K Jones, Laurence E Court, Moiz Ahmad

Faculty, Staff and Student Publications

Background: Variation in imaging protocol, patient positioning, and the presence of artifacts can vary image quality in CT images used for radiotherapy planning. Automated methods for spatial resolution (SR) estimation exist but require further investigation and validation for wider adoption.

Purpose: To validated previously existing algorithm for SR estimation and introduce improvements that make it robust to patient positioning, CT protocol, site, and artifacts.

Method: A reference algorithm based on the previous gold standard was recreated and modified to improve robustness. The algorithms were tested on three different datasets: (1) a cylindrical ACR CT QC phantom scanned using a Siemens …

American Association Of Physicists In Medicine (Aapm) Chapter Climate Check: Mixed Methods Analysis Of Survey Responses, Ashley J Cetnar, Ghada Aldosary, Meghan C Koo, Holly Lincoln, Angélica Pérez-Andújar, Surendra Prajapati, Samantha J Simiele, Kristi R G Hendrickson

Faculty, Staff and Student Publications

Introduction: The American Association of Physicists in Medicine (AAPM) recently shared results and recommendations from its first Equity, Diversity, and Inclusion (EDI) Climate Survey, which was designed to assess the climate at the workplace, the AAPM organization, and the AAPM regional chapter level. This work further explores the status of EDI at the regional chapter level.

Methods: AAPM's EDI Survey was distributed to 5500 members and had a response rate of 25%. In the survey, three open-ended comment boxes were provided for feedback, including one for regional AAPM members. Sixty-four percent of respondents indicated they were part of a regional …

Clinical Use Of Gafchromic Ebt4 Film For In Vivo Dosimetry For Total Body Irradiation, Emily Draeger, Fada Guan, Min-Young Lee, Dae Yup Han, William Donahue, Zhe Jay Chen

Faculty, Staff and Student Publications

Purpose: In vivo dosimetry is a common requirement to validate dose accuracy/uniformity in total body irradiation (TBI). Several detectors can be used for in vivo dosimetry, including thermoluminescent dosimeters (TLDs), diodes, ion chambers, optically stimulated luminescent dosimeters (OSLDs), and film. TLDs are well established for use in vivo but required expertise and clinical system availability may make them impractical for multifractionated TBI. OSLDs offer quick readout, but recalls have restricted their use. The purpose of this work was to validate the newly available Gafchromic EBT4 film for TBI in vivo dosimetry.

Methods: Film calibration curves were created under standard conditions …

An Automated Treatment Planning Portfolio For Whole Breast Radiotherapy, Hana Baroudi, Leonard Che Fru, Deborah Schofield, Dominique L Roniger, Callistus Nguyen, Donald Hancock, Christine Chung, Beth M Beadle, Kent A Gifford, Tucker Netherton, Joshua S Niedzielski, Adam Melancon, Manickam Muruganandham, Meena Khan, Simona F Shaitelman, Sanjay Shete, Patricia Murina, Daniel Venencia, Sheeba Thengumpallil, Conny Vrieling, Joy Zhang, Melissa P Mitchell, Laurence E Court

Faculty, Staff and Student Publications

Background: Automation in radiotherapy presents a promising solution to the increasing cancer burden and workforce shortages. However, existing automated methods for breast radiotherapy lack a comprehensive, end-to-end solution that meets varying standards of care.

Purpose: This study aims to develop a complete portfolio of automated radiotherapy treatment planning for intact breasts, tailored to individual patient factors, clinical approaches, and available resources.

Methods: We developed five automated conventional treatment approaches and utilized an established RapidPlan model for volumetric arc therapy. These approaches include conventional tangents for whole breast treatment, two variants for supraclavicular nodes (SCLV) treatment with/without axillary nodes, and two …

Iroc Phantoms Accurately Detect Mlc Delivery Errors, Sharbacha S Edward, Julianne M Pollard-Larkin, Peter A Balter, Rebecca M Howell, Christine B Peterson, Stephen F Kry

Faculty, Staff and Student Publications

Purpose: We evaluated the impact of random and whole-bank multileaf collimator (MLC) delivery errors on dosimetric delivery accuracy in the Imaging and Radiation Oncology Core (IROC) phantom audits, as well as differences in delivery accuracy between the IROC phantom prescription and typical clinical fraction sizes.

Methods and materials: Plans were created for the IROC IMRT head and neck (H&N) and SBRT spine phantoms. MLC leaf errors were introduced into the plans: random shifts between -2 and 2 mm, and whole bank shifts of 0.5, 1, and 2 mm. Plans were recalculated and delivered on a Varian Truebeam, and the log …

Rapidbrachyivbt: A Dosimetry Software For Patient-Specific Intravascular Brachytherapy Dose Calculations On Optical Coherence Tomography Images, Maryam Rahbaran, Jonathan Kalinowski, Joseph M Decunha, Kevin J Croce, Brian A Bergmark, James M G Tsui, Phillip M Devlin, Shirin A Enger

Faculty, Staff and Student Publications

Background: Coronary artery disease is the most common form of cardiovascular disease. It is caused by excess plaque along the arterial wall, blocking blood flow to the heart (stenosis). A percutaneous coronary intervention widens the arterial wall with the inflation of a balloon inside the lesion area and leaves behind a metal stent to prevent re-narrowing of the artery (restenosis). However, in-stent restenosis may occur due to damage to the arterial wall tissue, triggering neointimal hyperplasia, producing fibrotic and calcified plaques and narrowing the artery again. Drug-eluting stents, which slowly release medication to inhibit neointimal hyperplasia, are used to prevent …

On The Acceptance, Commissioning, And Quality Assurance Of Electron Flash Units, Allison Palmiero, Kevin Liu, Julie Colnot, Nitish Chopra, Denae Neill, Luke Connell, Brett Velasquez, Albert C Koong, Steven H Lin, Peter Balter, Ramesh Tailor, Charlotte Robert, Jean-François Germond, Patrik Gonçalves Jorge, Reiner Geyer, Sam Beddar, Raphael Moeckli, Emil Schüler

Faculty, Staff and Student Publications

Background and purpose: FLASH or ultra-high dose rate (UHDR) radiation therapy (RT) has gained attention in recent years for its ability to spare normal tissues relative to conventional dose rate (CDR) RT in various preclinical trials. However, clinical implementation of this promising treatment option has been limited because of the lack of availability of accelerators capable of delivering UHDR RT. Commercial options are finally reaching the market that produce electron beams with average dose rates of up to 1000 Gy/s. We established a framework for the acceptance, commissioning, and periodic quality assurance (QA) of electron FLASH units and present an …

Open-Chest Cardiac Ultrasound-Mediated Imaging With A Vacuum Coupler, Nilesh Mathuria, Krithik Vishwanath, Giorgio Brero, Blake C Fallon, Antonio Martino, Richard C Willson, Carly S Filgueira, Richard R Bouchard

Faculty, Staff and Student Publications

BACKGROUND: A fundamental obstacle for the preclinical development of ultrasound-(US) mediated cardiac imaging remains cardiac motion, which limits interframe correlation during extended acquisition periods.

PURPOSE: To address this need, we present the design and implementation of a 3D-printed vacuum coupler that stabilizes a US transducer on the epicardial surface of the heart for feasibility assessment and development of advanced, cardiac, US-mediated imaging approaches.

METHODS: The vacuum coupler was 3D printed with biocompatible resins and secured with a standard intraoperative suction aspirator. US-mediated imaging (i.e., B-mode and photoacoustic [PA] imaging) was performed in an open-chest porcine model with and without the …

Imaging Lung Tumor Motion Using Integrated-Mode Proton Radiography-A Phantom Study Towards Tumor Tracking In Proton Radiotherapy, Ryan Fullarton, Mikaël Simard, Lennart Volz, Allison Toltz, Savanna Chung, Christoph Schuy, Daniel G Robertson, Gary Royle, Sam Beddar, Colin Baker, Christian Graeff, Charles-Antoine Collins-Fekete

Faculty, Staff and Student Publications

BACKGROUND: Motion of lung tumors during radiotherapy leads to decreased accuracy of the delivered dose distribution. This is especially true for proton radiotherapy due to the finite range of the proton beam. Methods for mitigating motion rely on knowing the position of the tumor during treatment.

PURPOSE: Proton radiography uses the treatment beam, at an energy high enough to traverse the patient, to produce a radiograph. This work shows the first results of using an integrated-mode proton radiography system to track the position of moving objects in an experimental phantom study; demonstrating the potential of using this method for measuring …

Molecular Modification Of Queen Bee Acid And 10-Hydroxydecanoic Acid With Specific Tripeptides: Rational Design, Organic Synthesis, And Assessment For Prohealing And Antimicrobial Hydrogel Properties, Song Hong, Sachin B. Baravkar, Yan Lu, Abdul Razak Masoud, Qi Zhao, Weilie Zhou

School of Medicine Faculty Publications

Royal jelly and medical grade honey are traditionally used in treating wounds and infections, although their effectiveness is often variable and insufficient. To overcome their limitations, we created novel amphiphiles by modifying the main reparative and antimicrobial components, queen bee acid (hda) and 10-hydroxyl-decanoic acid (hdaa), through peptide bonding with specific tripeptides. Our molecular design incorporated amphiphile targets as being biocompatible in wound healing, biodegradable, non-toxic, hydrogelable, prohealing, and antimicrobial. The amphiphilic molecules were designed in a hda(hdaa)-aa1-aa2-aa3 structural model with rational selection criteria for each moiety, prepared via Rink/Fmoc-tBu-based solid-phase peptide synthesis, and structurally verified by NMR and LC–MS/MS. …

Customized Feminine Hygiene Wash Containing Postbiotics From Lactobacillus Spp. To Treat Urinary Tract Infections (Uti), Veena G. Nair

Theses and Dissertations

Probiotics, which support host health by maintaining normal microbial flora, offer a promising approach for preventing recurrent infections. To evaluate the prophylactic potential of vaginal probiotics against urinary tract infections (UTIs), we conducted a study on 54 healthy South Indian women aged 18–40 who visited the Obstetrics and Gynaecology outpatient clinic at Trichy SRM Medical College and Research Centre between June and July 2022. Vaginal swabs were collected following ethical guidelines, and commensal microbiota were isolated for probiotic characterization, with the broader objective of developing a customized feminine hygiene wash enriched with vaginal postbiotics.

Lactobacilli cell-free supernatant (CFS) demonstrated potent …