Radiation Medicine Commons^™

A Quantitative Dosimetric Comparison Of Dibh Vmat And Static-Imrt Apbi Treatments: Evaluating Large Left Sided Lumpectomy Cavities Located Near The Chest Wall, Christopher Jordan Clifton

Masters Projects

Abstract

Introduction

The main purpose of this study was to determine whether there was a significant difference between the dose distributions when comparing static-IMRT and VMAT plans for patients with large left sided lumpectomy cavities located near the chest wall while utilizing DIBH. Thorough planning and statistical analysis was performed to determine whether there was a clear advantage for either treatment technique to better benefit patient outcomes.

Methods

Ten female patients with large left sided lumpectomy cavities were selected to be retrospectively planned using both static-IMRT and VMAT plans. Each patient fell within the ASTRO eligibility criteria for APBI treatments. …

A Dosimetric Comparison Of Jaw Tracking Versus Non-Jaw Tracking Using 6mv Vmat Treatment Beams In Prostate Patients With Involved Lymph Nodes, Rebecca Todd

Masters Projects

Introduction:

Jaw tracking is the process of the collimator jaws dynamically following the multileaf collimators during modulated therapy. Jaw tracking can be used throughout the dosimetry treatment planning process for IMRT and VMAT treatment plans. It can reduce a patient’s OAR dose by reducing low dose spillage from MLC interleaf leakage. This study aims to investigate if jaw tracking reduces OAR dose while maintaining PTV coverage in prostate patients with involved lymph nodes using 6MV VMAT treatment planning technique.

Methods:

This is a quantitative study of 10 patients. For each patient, two plans were created, one plan using a non-jaw …

Longitudinal Diffusion And Volumetric Kinetics Of Head And Neck Cancer Magnetic Resonance On A 15 T Mr-Linear Accelerator Hybrid System: A Prospective R-Ideal Stage 2a Imaging Biomarker Characterization/Pre-Qualification Study, Joint Head And Neck Radiation Therapy-Mri Development Cooperative, Mr-Linac Consortium Head And Neck Tumor Site Group

Faculty, Staff and Student Publications

Objectives: We aim to characterize the serial quantitative apparent diffusion coefficient (ADC) changes of the target disease volume using diffusion-weighted imaging (DWI) acquired weekly during radiation therapy (RT) on a 1.5 T MR-Linac and correlate these changes with tumor response and oncologic outcomes for head and neck squamous cell carcinoma (HNSCC) patients as part of a programmatic R-IDEAL biomarker characterization effort.

Methods:Thirty patients with HNSCC who received curative-intent RT at MD Anderson Cancer Center, were included. Baseline and weekly MRI were obtained, and various ADC parameters were extracted from the regions of interest (ROIs). Baseline and weekly ADC parameters were …

Dosimetric Significance Of Manual Density Overrides In Oropharyngeal Cancer, Thomas Lo Greco

Masters Projects

Kilovoltage computed tomography plays a crucial role in radiotherapy planning. However, the presence of high-density metallic objects can introduce streaking artifacts in CT scans, resulting in inaccurate dose calculations by the treatment planning software. Previous studies have explored manual density overrides and artifact reduction algorithms individually to enhance dose calculation accuracy, but their combined application on patient plans within a treatment planning system remains unexplored.

This research aims to assess the necessity of manual density overrides when an artifact reduction algorithm is already employed to address dental artifacts in oropharyngeal cancer treatment plans. A total of 20 previously treated volumetric …

Intensity Modulated Bolus Electron Conformal Therapy (Im-Bect): Methods For Quality Assurance Of Prime Intensity Modulators And Evaluation Of Planned Im-Bect Dose Distributions, Andrew S. Mcguffey

LSU Doctoral Dissertations

Purpose: Intensity-modulated bolus electron conformal therapy (IM-BECT) shapes homogeneous dose distributions to superficial, irregularly-shaped target volumes, avoiding nearby critical structures. This dissertation provides research useful for translating IM-BECT to the radiotherapy clinic by: (1) developing and testing a factory quality assurance (QA) method for fabricated Passive Radiotherapy Intensity Modulator for Electrons (PRIME) devices and (2) verifying an IM-BECT planning and delivery process using end-to-end tests.

Methods: The IM-BECT planning and delivery process determines beam parameters and treatment devices (cutout, bolus, PRIME device) using .decimal’s (Sanford, FL) ElectronRT (eRT) planning system; calculates dose using a pencil-beam redefinition algorithm modified for PRIME …

Multiple Primary Lung Cancers: Treatment Outcomes After Stereotactic Body Radiotherapy (Sbrt), Gyujae Choi, George Chen, Weiyuan Mai, Albert Chen, Angela Zhu

Faculty, Staff and Students Publications

PURPOSE/OBJECTIVES: Patients with lung cancer sometimes present with multiple primary lung cancers (MPLCs), either simultaneously (synchronous) or after treatment of an initial lesion (metachronous). Although open surgery remains a treatment mainstay for patients with stage I-II non-small-cell lung cancer (NSCLC), stereotactic body radiation therapy (SBRT) is an acceptable alternative for patients who are medically unfit for or who refuse surgery. In this study, we retrospectively examine the outcome among patients with early-stage MPLCs treated at our institution with SBRT.

MATERIALS/METHODS: Patients at our institution receiving SBRT for MPLC between June 2011 and March 2020 were reviewed retrospectively. Prior to undergoing …

Addressing The Global Expertise Gap In Radiation Oncology: The Radiation Planning Assistant, Laurence Court, Ajay Aggarwal, Hester Burger, Carlos Cardenas, Christine Chung, Raphael Douglas, Monique Du Toit, David Jaffray, Anuja Jhingran, Michael Mejia, Raymond Mumme, Sikudhani Muya, Komeela Naidoo, Jerry Ndumbalo, Kelly Nealon, Tucker Netherton, Callistus Nguyen, Niki Olanrewaju, Jeannette Parkes, Willie Shaw, Christoph Trauernicht, Melody Xu, Jinzhong Yang, Lifei Zhang, Hannah Simonds, Beth M Beadle

Faculty, Staff and Student Publications

PURPOSE: Automation, including the use of artificial intelligence, has been identified as a possible opportunity to help reduce the gap in access and quality for radiotherapy and other aspects of cancer care. The Radiation Planning Assistant (RPA) project was conceived in 2015 (and funded in 2016) to use automated contouring and treatment planning algorithms to support the efforts of oncologists in low- and middle-income countries, allowing them to scale their efforts and treat more patients safely and efficiently (to increase access).

DESIGN: In this review, we discuss the development of the RPA, with a particular focus on clinical acceptability and …

Differences In Clinical Outcomes Based On Molecular Markers In Glioblastoma Patients Treated With Concurrent Tumor-Treating Fields And Chemoradiation: Exploratory Analysis Of The Spare Trial, Louis Cappelli, Mehak Majid Khan, Allison Kayne, Spencer Poiset, Ryan Miller, Ayesha Ali, Muneeb Khan Niazi, Wenyin Shi, Iyad Alnahhas

Department of Radiation Oncology Faculty Papers

Background: Glioblastoma (GBM) is the most common primary malignant brain tumor in adults. Despite enormous research efforts, GBM remains a deadly disease. The standard-of-care treatment for patients with newly diagnosed with GBM as per the National Cancer Comprehensive Cancer Network (NCCN) is maximal safe surgical resection followed by concurrent chemoradiation and maintenance temozolomide (TMZ) with adjuvant tumor treating fields (TTF). TTF is a non-pharmacological intervention that delivers low-intensity, intermediate frequency alternating electric fields that arrests cell proliferation by disrupting the mitotic spindle. TTF have been shown in a large clinical trial to improve patient outcomes when added to radiation and …

Long-Term Outcomes Of Bevacizumab And Chemoradiation For Locoregionally Advanced Nasopharyngeal Carcinoma: A Nonrandomized Controlled Trial, Nancy Y. Lee, Jonathan Harris, John Kim, Adam Garden, James Mechalakos, David G. Pfister, Anthony T.C. Chan, Kenneth Hu, A. Dimitrios Colevas, Steven Frank, George Shenouda, Voichita Bar-Ad, John N. Waldron, Paul M. Harari, Adam Raben, Pedro Torres-Saavedra, Quynh-Thu Le

Department of Radiation Oncology Faculty Papers

IMPORTANCE: The long-term outcomes associated with adding bevacizumab, a vascular endothelial growth factor inhibitor, to standard chemoradiation have continued to be favorable for a group of patients with locoregionally advanced nasopharyngeal carcinoma (NPC).

OBJECTIVE: To assess long-term toxic effects and clinical outcomes associated with chemotherapy, radiation therapy (RT), and bevacizumab for NPC.

DESIGN, SETTING, AND PARTICIPANTS: This single-arm phase II nonrandomized controlled trial was conducted by the National Cancer Trials Network group and NRG Oncology (formerly Radiation Therapy Oncology Group), with accrual from December 13, 2006, to February 5, 2009, and data analysis from June 26 to July 1, 2019. …

Internal Lead Shielding For Clinical Electron Treatments, Patrick N. Mcdermott

Conference Presentation Abstracts

Purpose: Electron beams are often used to treat superficial lesions of the lip, cheek, nose and ear. Lead is frequently used to block distal structures. It is customary to place an internal bolus of low atomic number in between the tissue and the lead to reduce electron backscatter from the lead. Space for the lead and the internal bolus is quite limited. The current method, recommended by TG25, for estimating the thickness of the lead plus internal bolus is not self-consistent and leads to a larger than necessary thickness. Furthermore, this method uses an older expression for the electron backscatter …

Application Of A Novel Optical Tool For Linac Calibrations, Cory S. Knill, Brian Loughery, Raminder P. Sandhu, Lifeng Lin, Mark Stefani

Conference Presentation Abstracts

Purpose: Maintaining a linac within tight stereotactic isocentricity tolerances requires minimizing errors in individual components of the linac. However, while isocentricity can be measured using a Winston-Lutz test, contributions from individual components can be difficult to discern. The disconnect between how individual components contribute to isocentricity can lead to lengthy troubleshooting exercises when isocentricity is outside tolerance. To provide more info rmation to physicists and increase the speed of isocentricity adjustments, a new tool that uses optical tracking to investigate and adjust individual linac components that contribute to isocentricity was tested on three clinical linacs. Methods: The optical tracking tool …

Develop A Novel Beam Orientation Optimization Algorithm For Let (Linear Energy Transfer) Incorporated Impt (Intensity Modulated Proton Therapy) (Imptlet, R Dao, Y Qian, Xiaoqiang Li, H Quan, Xuanfeng Ding, G Liu

Conference Presentation Abstracts

Purpose: To improve the dose and LET distribution in the IMPTLET, we introduce a new optimization algorithm to search for the optimal beam orientation and count through the arc trajectory (BOC-IMPTLET). Methods: We introduce kmeans clustering analysis in the BOC-IMPTLET algorithm by analyzing the distribution of LET in the target from the full arc trajectory. The optimal of cluster count was used as beam count, which was determined based on the SSE (Sum of Square Error) value and the angle of the corresponding centroid of each cluster was used as beam orientation, respectively. The BOC-IMPTLET algorithm was implemented in the …

Physician Perceptions On Cancer Screening For Lgbtq+ Patients, Nicolas Nelson, Joseph F. Lombardo, Ayako Shimada, Marissa L. Ruggiero, Alexandria P. Smith, Kevin Ko, Amy E. Leader, Edith P. Mitchell, Nicole L. Simone

Department of Radiation Oncology Faculty Papers

The LGBTQ+ community experiences cancer disparities due to increased risk factors and lower screening rates, attributable to health literacy gaps and systemic barriers. We sought to understand the experiences, perceptions, and knowledge base of healthcare providers regarding cancer screening for LGBTQ+ patients. A 20-item IRB-approved survey was distributed to physicians through professional organizations. The survey assessed experiences and education regarding the LGBTQ+ community and perceptions of patient concerns with different cancer screenings on a 5-point Likert scale. Complete responses were collected from 355 providers. Only 100 (28%) reported past LGBTQ+-related training and were more likely to be female (p = …

Endovascular Exclusion Of Ascending Aortic Pseudoaneurysm With An Experimental Ascending Aortic Stent-Graft, Chibueze Onyemkpa, Joseph S Coselli

Faculty, Staff and Students Publications

No abstract provided.

Effect Of Sarcopenia On Survival And Spinal Cord Deficit Outcomes After Thoracoabdominal Aortic Aneurysm Repair In Patients 60 Years Of Age And Older, Subhasis Chatterjee, Ann Shi, Luke Yoon, Susan Y Green, Qianzi Zhang, Hiruni S Amarasekara, Vicente Orozco-Sevilla, Ourania Preventza, Scott A Lemaire, Joseph S Coselli

Faculty, Staff and Students Publications

Objective: Sarcopenia (core muscle loss) has been used as a surrogate marker of frailty. We investigated whether sarcopenia would adversely affect survival after thoracoabdominal aortic aneurysm repair.

Methods: We retrospectively reviewed prospectively collected data from patients aged 60 years or older who underwent thoracoabdominal aortic aneurysm repairs from 2006 to 2016. Imaging was reviewed by 2 radiologists blinded to clinical outcomes. The total psoas index was derived from total psoas muscle cross-sectional area (cm2) at the mid-L4 level, normalized for height (m2). Patients were divided by sex-specific total psoas index values into sarcopenia (lower third) and nonsarcopenia (upper two-thirds) groups. …

A Case Report Of Unusual Presentation Of A Rare Renal Tumor, Farzaneh Sharifiaghdas, Behzad Narouie, Mohammad Ghasemi-Rad, Fatemeh Moosavian, Mohadese Ahmadzade, Hamidreza Rouientan

Faculty, Staff and Students Publications

There are very few cases of primary renal Ewing sarcomas, which are characterized by a high rate of metastasis. These tumors are often mistaken for other more common kidney tumors due to their rarity and lack of pathognomonic symptoms in the early stages. A 28-year-old male patient presented to our clinic with a 2-month history of nonproductive progressive cough and left flank pain. The chest was scanned with contrast-enhanced computed tomography, which showed a heterogeneously enhancing mass with central vascularity on the left retroperitoneal. An abdominal dynamic multiphasic magnetic resonance imaging with contrast revealed a large mass that was highly …

Three-Dimensional Microct Imaging Of Mouse Heart Development From Early Post-Implantation To Late Fetal Stages, Nanbing Li-Villarreal, Tara L Rasmussen, Audrey E Christiansen, Mary E Dickinson, Chih-Wei Hsu

Faculty, Staff and Students Publications

Comprehensive detailed characterization of new mouse models can be challenging due to the individual focus involved in developing these models. Often models are engineered to test a specific hypothesis in a limited number of tissues, stages, and/or other contexts. Whether or not the model produces the desired phenotypes, phenotyping beyond the desired context can be extremely work intensive and these studies are often not undertaken. However, the general information resulting from broader phenotyping can be invaluable to the wider scientific community. The International Mouse Phenotyping Consortium (IMPC) and its subsidiaries, like the Knockout Mouse Project (KOMP), has made great strides …

A Novel Planning Framework For The Efficient Spot-Scanning Proton Arc Therapy Via The Particle Swarm Optimization (Sparc-Particle Swarm), Y Qian, R Dao, G Liu, Xiaoqiang Li, H Quan, Xuanfeng Ding

Conference Presentation Abstracts

Purpose: The delivery efficiency is the bottleneck of spot-scanning proton arc therapy (SPArc) because of the numerous energy layers (EL) ascending switches. This study aims to develop a new algorithm to mitigate the need of EL ascending via water equivalent thickness (WET) sector selection followed by the particle swarm optimization (SPArc- particle swarm). Methods: SPArc- particle swarm divided the full arc trajectory into the optimal sectors based on the K-means clustering analysis of the relative mean WET. Within the sector, particle swarm optimization was used to minimize the total energy switch time, in which it optimized the energy selection integrated …

Individual Vmat Beam Complexity Indices Have Limited Predictive Value For Qa Pass-Rates, Jian Liang, Q Liu, David T. To, Michael G. Snyder

Conference Presentation Abstracts

Purpose: Previous studies with sample sizes <400 have indicated that VMAT beam complexity indices may have a relationship with measured QA pass-rates. The aim of this study is to evaluate such relationships on a large scale to further investigate their strength. Methods: Total of 17,273 VMAT QA results across 8 Elekta Agility machines were used in this study. All beams were flattened 6MV or 10MV. Sun Nuclear ArcCheck was used for QA measurements with γ-analysis parameters of 10% threshold, 3% dose difference, 2mm distance to agreement, and 95% passing threshold. A total 214 Beams (1.23%) failed QA. QA distributions in Pinnacle were calculated with 2 degree gantry intervals and a dose grid of 2mm. Four complexity indices (MCSv, MU weighted Segment Area, Segment Area/Perimeter, and Average Leaf Gap) were computed. Spearman’s correlations were evaluated for each, and cut-off values for the indices were sought to indicate values above which no QA failures would be expected. Results: Evaluation of the 4 complexity metrics showed weak correlation with QA pass rates (< ±0.42) with high significance (p < 0.001). When metrics were evaluated independently, cut-off values from correlation plots separated only 0.67%, 0.72%, 2.2%, 6.3% guaranteed passing beams from the total sample, respectively. When evaluating whether anymetric for a given beam exceeded its cut-off, the fraction of guaranteed passing beams rose to only 6.6%. However, when cut-off values for one metric were allowed to be functionally dependent upon another, the fraction of guaranteed passing beams increased. For MU weighted Segment Area andAverage Leaf Gap, a dependent approach separated 19.1% guaranteed passing beams from the sample. Conclusion: Individual complexity metrics have weak predictive utility in assessing plan performance. However, using multiple complexity cut-off functions with dependence upon more than one metric increased the fraction of predicted passing beams by around 300%.

The Clinical Usability, Efficiency, And Accuracy Of Combining Deep-Learning-Based Synthetic Ct And Auto-Contouring For Daily Cbct-Based Online Adaptive Radiation Therapy, An Qin, J Xu, N O'Connell, Xuanfeng Ding, Shupeng Chen, D Thill

Conference Presentation Abstracts

Purpose: To evaluate the feasibility of deep-learning and CBCT-based online adaptive radiotherapy(ART) in thorax, Head&Neck, and pelvic regions. Methods: The study utilized ADMIRE(Advanced Medical Image Registration Engine), a research software designed to enable fast online ART through: (1)synthetic CT(sCT) generation from CBCT, (2)automatic segmentation of critical organs(OARs), and(3)deformable image registration(DIR) to transfer the target volume. ADMIRE trained a modified Cycle-Generative-Adversarial-Networks with Structural Similarity Index Map(SSIM) loss term to generate sCT, while the auto-segmentation model was based on a 3D-ResUnet with modification. Site-specific models were trained for three anatomic sites: thorax, pelvic, and head&neck, and for both networks. The study included …