Radiation Medicine Commons^™

Mechanistic Insights Into The Flash Effect: The Role Of Oxygen And Radiation Chemistry In Ultra-High Dose Rate Radiation Therapy, Jacob Pierce Sunnerberg

Dartmouth College Ph.D Dissertations

The development of new cancer therapies focuses on widening the therapeutic ratio between tumor control and normal tissue toxicity. Over the last decade, ultra-high dose rate (UHDR) radiation therapy, commonly known as FLASH radiotherapy (FLASH-RT), has shown promising potential to reduce normal tissue toxicity while maintaining tumor control. However, the underlying mechanisms of the FLASH effect remain poorly understood. This thesis explores the radiation-chemical basis of FLASH-RT, focusing on the role of oxygen and reactive oxygen species in modulating biological outcomes.

A comprehensive set of in vitro studies demonstrated that UHDR delivery significantly alters radiation chemistry compared to conventional dose …

Impact Of Post-Operative Radiation Therapy On Survival In Nsclc Patients With Incomplete Surgical Resection, Farrah R. Khan Md

Posters

Postoperative radiation therapy (PORT) has a limited role in the management of resectable non-small cell lung carcinoma (NSCLC). A relatively strong indication for its use is in the presence of residual tumor after surgical resection, as PORT has been shown to improve survival in such patients. However, it is unclear how much of the survival detriment of incomplete resection PORT is able to offset compared to negative margins. We aim to answer this question in our study

Automated Radiotherapy Treatment Planning For Breast Cancer: A Robust To Ol For Global Deployment, Hana Baroudi

Dissertations and Theses (Open Access)

Breast cancer incidence continues to rise worldwide, particularly in low- and middle-income countries, where limitations in resources already constrain access to timely care. Radiotherapy is a cornerstone of breast cancer management, proven to significantly lower both recurrence and mortality. However, a growing shortage of radiation staff worldwide threatens the prompt delivery of these treatments.This thesis proposes an automated solution to address the limited accessibility of radiotherapy planning in breast cancer management by developing an end-to-end automated treatment planning model and evaluating its performance and limitations across diverse patient populations.

An automated contouring model was trained using data from 104 whole-breast …

A Comparative Analysis Of Helical Tomotherapy Planning With Active Versus Total Bone Marrow Sparing Using Dual-Energy Computed Tomography, April E. Premo

Masters Projects

Purpose: This study aims to compare helical tomotherapy (HT) plans using active bone marrow (ABM) sparing contouring versus traditional bone marrow (BM) sparing contouring using dual-energy computed tomography (DECT) in the treatment of gynecologic (GYN) cancers. The goal is to evaluate the effects of using ABM contours in optimization on organs at risk (OAR) and planning target volumes (PTVs).

Methods: The study involved creating HT plans for GYN cancer patients, utilizing both ABM and BM contouring techniques. DECT was used to distinguish between active and inactive bone marrow. Dosimetric comparisons were made between BM and ABM sparing plans. Statistical analyses …

Plan Comparison Of Hybrid Dynamic Conformal Arc Therapy (Hdcat) And 3-Dimensional Conformal Radiation Therapy (3dcrt) In Palliative Treatment Of Thoracic Spine Tumors, Maria Juchartz

Masters Projects

Abstract

Introduction

When cancer spreads from its place of origin to a new location, it is termed ‘metastatic’. Metastatic cancer is often not curable, however palliative care can be given. One common method of palliation is in the form of radiation therapy. A common site of metastasis is in the thoracic spine, which has several nearby organs that can make treatment planning difficult. These treatments often consist of three-dimensional conformal radiotherapy methods. The purpose of this study was to compare the traditional 3DCRT techniques to a hybrid dynamic conformal arc technique. HDCAT has been used in previous studies, however none …

Acute Pain Prediction In Oral Cavity And Oropharyngeal Cancer Patients Receiving Radiation Therapy, Vivian Salama

Dissertations and Theses (Open Access)

Oral-Cavity and oropharyngeal cancers (OC/OPC) are types of head and neck cancers that are increasing in incidence domestically. Radiation therapy (RT) is crucial in OC/OPC management. Pain is a common and challenging symptom for most patients during therapy, as nearly all patients undergoing locoregional RT in OC/OPC require analgesia for acute iatrogenic pain. Moreover, about 45% of long-term survivors report chronic pain, with more than 10% exhibiting severe chronic pain. Pain control is challenging due to the multifactorial clinical, molecular, and cellular etiology of cancer/therapy pain, as well as variation in pain assessment and the non-uniform management of pain between …

Evaluation Of An End-To-End Radiotherapy Treatment Planning Pipeline For Prostate Cancer, Mohammad Daniel El Basha, Court Laurence, Carlos Eduardo Cardenas, Julianne Pollard-Larkin, Steven Frank, David T. Fuentes, Falk Poenisch, Zhiqian H. Yu

Dissertations and Theses (Open Access)

Radiation treatment planning is a crucial and time-intensive process in radiation therapy. This planning involves carefully designing a treatment regimen tailored to a patient’s specific condition, including the type, location, and size of the tumor with reference to surrounding healthy tissues. For prostate cancer, this tumor may be either local, locally advanced with extracapsular involvement, or extend into the pelvic lymph node chain. Automating essential parts of this process would allow for the rapid development of effective treatment plans and better plan optimization to enhance tumor control for better outcomes.

The first objective of this work, to automate the treatment …

Methods For The Prediction Of Osteoradionecrosis Resulting From Head And Neck Cancer Radiation Therapy, Brandon Reber

Dissertations and Theses (Open Access)

Head and neck cancer (HNC) is the sixth most diagnosed cancer worldwide with over 600,000 patients diagnosed every year. One of the primary methods to treat HNC is through radiation therapy (RT). While RT is effective at treating HNC, late toxicities resulting from treatment can occur months to years post-treatment and can cause debilitating quality of life changes for HNC survivors. One of these late toxicities is osteoradionecrosis (ORN), which is the death of bone due to radiation. For HNC, the mandible is commonly affected and can cause challenges chewing, swallowing, and physical appearance changes. Several factors indicate the pressing …

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 …

Prospective Validation Of Diffusion-Weighted Mri As A Biomarker Of Tumor Response And Oncologic Outcomes In Head And Neck Cancer: Results From An Observational Biomarker Pre-Qualification Study, Abdallah S R Mohamed, Abdelrahman Abusaif, Renjie He, Kareem A Wahid, Vivian Salama, Sara Youssef, Brigid A Mcdonald, Mohamed Naser, Yao Ding, Travis C Salzillo, Moamen A Abobakr, Jihong Wang, Stephen Y Lai, Clifton D Fuller

Faculty, Staff and Student Publications

PURPOSE: To determine DWI parameters associated with tumor response and oncologic outcomes in head and neck (HNC) patients treated with radiotherapy (RT).

METHODS: HNC patients in a prospective study were included. Patients had MRIs pre-, mid-, and post-RT completion. We used T2-weighted sequences for tumor segmentation which were co-registered to respective DWIs for extraction of apparent diffusion coefficient (ADC) measurements. Treatment response was assessed at mid- and post-RT and was defined as: complete response (CR) vs. non-complete response (non-CR). The Mann-Whitney U test was used to compare ADC between CR and non-CR. Recursive partitioning analysis (RPA) was performed to identify …

The Safe And Effective Clinical Deployment Of Artificial Intelligence To Ols, Kelly Nealon

Dissertations and Theses (Open Access)

18 million new cancer cases are diagnosed each year. Roughly half of these patients will be treated with radiation therapy, a complex technique that requires an interdisciplinary team of clinical staff and expensive equipment to be delivered safely. Cancer centers in Low- and Middle-Income Countries (LMIC) have an especially difficult time meeting the demands of radiation therapy as the complexity of treatment techniques increase, with only 37% of patients in these regions having access to the care they need. Artificial Intelligence (AI) based tools are being developed to simplify the treatment planning and quality assurance processes to increase the number …

Analysis Of Biologically Effective Dose For Retroactive Yttrium-90 Trans-Arterial Radioembolization Treatment Optimization, Mj Lindsey

CMC Senior Theses

Trans-arterial radioembolization (TARE) is a protracted modality of radiation therapy where radionuclides labeled with Yttrium-90 (⁹⁰Y) are inserted inside a patient's hepatic artery to treat hepatocellular carcinoma (HCC). While TARE has been shown to be a clinically effective and safe treatment, there is little understanding of the radiobiological relationship between absorbed dose and tissue response, and thus there is no dosimetric standard for treatment planning. The Biologically Effective Dose (BED) formalism, derived from the Linear-Quadratic model of radiobiology, is used to weigh the absorbed dose by the time pattern of delivery. BED is a virtual dose that can …

Infrastructure Development For Personalized Risk Prediction To Reduce Cardiovascular Disease In Childhood Cancer Survivors, Suman Shrestha

Dissertations and Theses (Open Access)

Although childhood cancer survivors have lengthy life expectancies, they run the risk of experiencing long-term health issues as a result of their treatment. The most frequent non-cancerous cause of morbidity and mortality for these survivors is cardiac disease. Radiation therapy (RT) has been linked in numerous cohort studies to a higher chance of developing a late cardiac disease in these survivors, and this risk rises with higher mean heart doses and increased RT exposure to larger cardiac volumes. Since, the heart is a heterogeneous organ made up of several distinct substructures, RT dose received by the entire heart does not …

Structure Sparsity Of The Spot Optimization In Proton Arc Therapy, Lewei Zhao

Conference Presentation Abstracts

Radiation therapy is one of the main cancer treatments that uses radiation to kill cancer cells. Proton therapy, or proton radiotherapy, is a type of particle therapy that uses a beam of protons to irradiate tumor volume. Beaumont proton therapy center research group invented the first robust and delivery-efficient spot-scanning proton arc (SPArc) therapy in 2016. Based on our beam modeling platform, we have found that the spot switching time (SSWT) is proportional to spot numbers. We aim to develop a direct mathematical optimization method to reduce the spot numbers for SPArc based on an independent optimization method to reduce …