Radiation Medicine Commons^™

Evaluating Dosimetric Outcomes In A Prostate Rapid Plan Model: A Comparison Of Prostate Treatment Plans With And Without Standardized Planning Structures, Erica Wartman

Masters Projects

Abstract

Knowledge-based planning (KBP) using RapidPlan (RP) has demonstrated the ability to produce high quality radiation therapy treatment plans while reducing time. This study evaluated whether the inclusion of department specific standardized planning structures, including rings and other optimization tools, improves plan quality when using a prostate and lymph node RP model, or if the model alone is sufficient to provide a quality plan without the use of these additional planning structures.

Ten previously treated Prostate+LN patients were replanned using the departmental RP model in Varian Eclipse treatment planning system.1 For each patient, two plans were created, one with standardized …

Evaluating Parotid Gland Dose Between Electronic Tissue Compensation And Field In Field Treatment Techniques For Parotid Sparing In Whole-Brain Radiotherapy, Joesph E. Bodgonas

Masters Projects

Purpose:

The parotid glands are essential to salivary function and patient quality of life, yet they are not routinely prioritized as organs at risk (OARs) during whole-brain radiotherapy (WBRT). With growing recognition of long-term side effects like xerostomia in patients with prolonged survival after WBRT, parotid-sparing techniques warrant investigation. This study compares radiation dose to the parotid glands using three different 3D conformal WBRT planning approaches: field-in-field (FiF) with blocking, electronic tissue compensation (eCOMP) without blocking, and eCOMP with blocking.

Methods and Materials:

A retrospective study was conducted on 20 patients previously treated with 3D conformal WBRT. Original eCOMP plans …

A Comparative Study Of Vmat Beam Arrangements In Large Field Nodal Prostate Treatment Plans, Laura R. Black

Masters Projects

Treatment of extensive prostate and pelvic lymph node volumes for prostate cancer patients provide unique challenges related to limitations in multileaf collimator (MLC) design in many modern linear accelerators. A strategy to overcome this challenge is by restricting the field size, improving modulation as well as using overlapping arcs to ensure complete coverage of the target. Using too few arcs can result in suboptimal target coverage, while too many arcs can lead to prolonged time on the table, increasing the risk of patient movement and potential side effects that may compromise treatment accuracy. This study aims to evaluate the optimal …

Evaluating Coplanar And Noncoplanar Treatment Plans For The Varian Halcyon And Varian Truebeam For Intact Prostate Patients., Ashley Coppage

Masters Projects

Prostate cancer is among the most treated malignancies with radiation therapy, where precise dose delivery is critical for tumor control and minimizing toxicity. VMAT is widely adopted due to its efficiency and conformity; however, the choice between coplanar and non-coplanar beam arrangements remains an area of ongoing investigation, especially with newer platforms like Halcyon and TrueBeam. This retrospective dosimetric study compares coplanar and non-coplanar volumetric modulated arc therapy (VMAT) treatment plans for intact prostate cancer patients using the Varian Halcyon and Varian TrueBeam systems. Plans were created using a standardized protocol within Eclipse v16.1, with all Halcyon plans employing coplanar …

Radiation Induced Vaporization Of Exoskeletal Droplets As Potential X-Ray Acoustic Contrast Agents, Mohamed E. Eldib, William N. Frantz, Mark A. Borden, Ryan Lanning, Moyed Miften, David H. Thomas

Department of Radiation Oncology Faculty Papers

BACKGROUND: In vivo dosimetry is a crucial component of ensuring accurate and safe radiation therapy (RT) delivery, but many existing techniques face challenges such as low signal-to-noise ratio (SNR), which can limit their clinical applicability.

PURPOSE: In this study, we investigate a novel contrast agent sensitive to megavoltage (MV) radiation in vitro, ultimately aiming for in vivo dosimetry.

METHODS: Vaporizable exoskeletal droplets were engineered to phase-change into ultrasound-responsive microbubbles upon exposure to MV photon radiation. These droplets comprised a hydrocarbon (HC) exoskeleton doped with gold nanoparticles (GNPs) surrounding a liquid fluorocarbon (FC) core. Radiation absorbed by the GNPs induced localized …

Dosimetric Comparisons Of 6mv, 6fff, 10mv, And 10fff On Vmat Planning In Patients With Endometrial Cancer, Madisin M. Depas

Masters Projects

Purpose: This study aimed to evaluate the dosimetric and efficiency impacts of different photon beam energies—6MV, 6 flattening filter free (FFF), 10MV, and 10FFF—on volumetric modulated arc therapy (VMAT) plans for endometrial cancer, with attention to target coverage, organ at risk (OAR) sparing, and treatment efficiency.

Methods: A retrospective analysis was conducted on 25 patients with post-hysterectomy endometrial cancer. Each patient received four VMAT plans with varying energies. Planning metrics assessed included planning target volume (PTV) dose maximum (Dmax), conformity index (CI), heterogeneity index (HI), OAR doses (bladder, bowel, rectum), and total monitor units (MU). Correlations were drawn …

Dosimetric Effects Of Pinnacle³ Version 18.0 Advanced Auto-Planning Settings In Oropharyngeal Vmat Optimization, Emily Sanden

Masters Projects

This study evaluated the impact of Pinnacle³ version 18.0 auto-planning advanced settings modulation amount, monitor unit (MU) level, and dose fall-off priority on volumetric modulated arc therapy (VMAT) plan quality for bilateral oropharyngeal cancer. A total of 64 plans were generated using all possible combinations of low, medium, high, and very high settings for each parameter. A standardized base of tongue case was optimized once per plan using a single-time point approach, with planned target volume 1 (PTV1) (6996 cGy) and planned target volume 2 (PTV2) (5412 cGy) coverage evaluated. Each parotid gland, the spinal cord, brainstem, and the oral …

Impact Of Prostate Volume On Dose Fall-Off And Organ-At-Risk Exposure In Vmat For Prostate Cancer, Zhikang Jiang

Masters Projects

Prostate cancer remains one of the most prevalent malignancies among men, with radiotherapy, particularly VMAT—playing a central role in its management. VMAT allows for highly conformal dose delivery, but treatment planning must strike a careful balance between achieving steep dose gradients around the prostate and minimizing radiation exposure to nearby organs at risk (OARs), such as the bladder and rectum. This study aimed to evaluate how prostate volume influences dose fall-off characteristics and OAR dose exposure in VMAT treatment plans, providing insights into optimizing radiotherapy for patients with varying prostate sizes. A retrospective analysis was conducted on 50 prostate cancer …

Comparing Dosimetric Outcomes Of Static Imrt And Vmat In Accelerated Partial Breast Irradiation For Medially Located, Left-Sided Tumor Beds, Rani Jamil

Masters Projects

Abstract

Introduction: Accelerated partial breast irradiation (APBI) has emerged as a targeted alternative to whole-breast irradiation for early-stage breast cancer, particularly for patients with medially located, left-sided tumors. Static intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) offer advanced dose conformity, yet no direct comparisons between static IMRT and VMAT have been conducted specifically for medially located, left-sided APBI, a uniquely challenging anatomical subgroup. This study evaluates dosimetric differences between static IMRT and VMAT plans to determine which modality provides superior target coverage and organ-at-risk (OAR) sparing in left-sided APBI.

Methods: Ten patients with medially located left-sided breast …

Investigating The Necessity Of Adaptive Radiotherapy In Tomotherapy Of Head And Neck Cancer Patients, Ali Chaparian, Mahsa Kianinia, Mahnaz Roayaei, Nadia Najafizade, Abolfazl Kanani, Leili Mahani, Hamidreza Nourzadeh

Department of Radiation Oncology Faculty Papers

BACKGROUND: Anatomical variations that occur during radiation therapy in head and neck cancer (HNC) patients can lead to significant dosimetric changes. The purpose of this study is to evaluate dosimetric and volume changes in key anatomical structures for different treatment sites in HNC patients, and to determine the percentage of patients who need adaptive radiotherapy (ART) per treatment site.

METHODS: A total of 1,740 megavoltage computed tomography (MVCT) images from 58 HNC patients treated with helical tomotherapy (HT) were exported to the PreciseART™ (Accuray) software. Volume changes in the planning target volume (PTV) and the organs at risk (OARs) in …

Dosimetric Comparisons For Determining Optimal Arc Geometry In Multi Target Thoracic Vmat Sbrt Treatment Plans For Patients With Locally Advanced Inoperable Nsclc, Alexandrea M. Reeves

Masters Projects

Non-coplanar beam arrangements have been used for many years in radiation treatment planning. Their use has been known to show an increase in target conformity and gradient index. However, by using non-coplanar beam arrangements, the treatment planning time as well as the treatment delivery time can increase. Despite the increase in treatment planning and delivery complexity and time, previous studies have shown a decrease in OAR doses resulting in a desire to use non-coplanar beams. Previous studies have looked at various body sites and target locations, though no research has been found specifically studying non-coplanar beam arrangement in multi-target treatment …

Comparing And Evaluating Contralateral Breast Dose Relative To Median Ptv Tumor Bed Dose For Hypo-Fractionated Breast Treatments Using Import High Dose Constraints., Shannon J. Nordby

Masters Projects

This study is aimed to compare two different planning constraints for post-lumpectomy whole breast radiation treatments to evaluate whether or not the mean dose to the contralateral breast can be significantly reduced while maintaining plan quality for treatment. A total of 10 patients who had first undergone a lumpectomy were included into this study. Each patient’s initial treatment plan was created using a conventional approach with a mean dose constraint of < 600 cGy (Plan A) and then was replanned using the Import High protocol of a mean dose constraint, aiming to further push for a mean dose < 150 cGy (Plan B) to the contralateral breast. Both of these plans were analyzed for PTV coverage and dose to the surrounding critical structures. The results have shown that the contralateral mean dose was significantly reduced from an average of 216.32 in Plan A to 126.53 cGy in Plan B. All while meeting the target coverage of > 95% isodose line. Statistical testing showed a significant difference between the two planning techniques of lowering the contralateral dose (p < 0.0001), and normality testing supported the validity of the data analysis. In addition to a substantial dose reduction to the contralateral breast, Plan B maintained equal or improved dose constraint to other surrounding critical organs at risk, including the heart, lungs, spinal cord, and thyroid. The Import High protocol demonstrated consistent outcomes across diverse patient anatomies. These findings suggest that by using the Import High mean dose constraint, it is possible to maintain plan quality while reducing dose to the contralateral breast. This approach may help reduce the risk of long-term side effects and improve the patient’s overall outcomes in whole breast radiation treatments.

First Quantitative Investigation On The Dosimetric Perturbation From Dental Hardware In Spot-Scanning Proton Arc (Sparc®) Therapy And Planning Strategies In Head Neck Cancer Patient Population, Evan Harbert

Masters Projects

Purpose

There has been a tremendous interest in applying Spot-scanning Proton Arc (SPArc^®) to benefit head and neck cancer (HNC) patient population. However, the dental hardware materials effects on the beam distribution are not well understood, and placing spots through the dental hardware may cause an unnecessary degradation of target coverage if the material components differ from the nominal plan. The purpose of this study is to provide a quantitative dose perturbation analysis of the uncertainties caused by dental hardware and introduce a SPArc^® planning strategy to mitigate such impacts.

Methods and Materials

A published in-house developed …

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 …

Cone Beam Ct Dose Optimisation: A Review And Expert Consensus By The 2022 Estro Physics Workshop Igrt Working Group, Lydia J. Wilson, Andria Hadjipanteli, Daniella E. Østergaard, Evelien Bogaert, Kirstie F. Brown, Rianne Dejong, James Earley, Magali Edouard, Marina Khan, Josh Lindsay, Jessica Van Der Himst, George X. Ding, Tim Wood, Marianne C. Aznar, Nuria Jornet, Georgios Ntentas

Department of Radiation Oncology Faculty Papers

Image guided radiotherapy (IGRT) using kilovoltage cone-beam CT (CBCT) has become an indispensable tool to ensure the geometric accuracy of radiotherapy treatment delivery. Although significant technical advances have been made in reducing imaging dose, the repeated imaging procedures can still accumulate significant dose to healthy tissues. Despite the widespread use, we still lack clear guidance for optimisation and widely accepted frameworks for evaluating the quality and suitability of CBCT imaging protocols. To address this gap, the 2022 European Society for Radiotherapy and Oncology (ESTRO) Physics Workshop focused on image-quality and imaging-dose optimisation for IGRT using CBCT. This publication represents a …

A Semiclassical Model Of The Immediate Temperature Distribution Surrounding The Track Of Heavy Ions With Therapeutic Energies, Martin Rädler, Niayesh Afshordi, Reza Taleei, Katia Parodi, Ramin Abolfath, Julie Lascaud

Department of Radiation Oncology Faculty Papers

Objective. Spikes of high temperature and pressure are created in the vicinity of heavy ions, especially at the Bragg peak. The expected subsequent thermoacoustic effects are however not well understood. In particular, the distribution of the densely packed primary interactions has not been considered in molecular dynamics (MDs) simulations or shock wave solutions. In this work, we derive a dedicated model to describe the primary interactions and their radial distribution, applicable to the modeling of acoustic and thermodynamic effects at the nanoscale. Approach. Starting from first principles, we assemble a semiclassical model of the energy loss of the primary heavy …

Decoding Resistance To Immune Checkpoint Inhibitors In Non-Small Cell Lung Cancer: A Comprehensive Analysis Of Plasma Proteomics And Therapeutic Implications, Michal Harel, Nili Dahan, Coren Lahav, Eyal Jacob, Yehonatan Elon, Igor Puzanov, Ronan J. Kelly, Yuval Shaked, Raya Leibowitz, David P. Carbone, David R. Gandara, Adam P. Dicker

Department of Radiation Oncology Faculty Papers

BACKGROUND: Immune checkpoint inhibitors (ICIs) have shown substantial benefit for patients with advanced non-small cell lung cancer (NSCLC). However, resistance to ICIs remains a major clinical challenge. Here, we perform a comprehensive bioinformatic analysis of plasma proteomic profiles to explore the underlying biology of treatment resistance in NSCLC.

METHODS: The analysis was performed on 388 "resistance-associated proteins" (RAPs) that were previously described as pretreatment plasma proteomic predictors within the PROphet computational model designed to predict ICI clinical benefit in NSCLC. Putative tissue origins of the RAPs were explored using publicly available datasets. Enrichment analyses were performed to investigate RAP-related biological …

Treatment Outcomes Following Tme For Biologically Unfavorable Locally Advanced Rectal Cancer, Maryam Aleissa, Amr Aref, Hussein Gharib, Ernesto R. Drelichman, Amer Zeni, Amer Alame, Jasneet S. Bhullar

Conference Presentation Abstracts

Purpose/Background: Many centers now offer organ preservation for selected patients with locally advanced rectal cancer. Our group initiated three Phase II trials to assess the safety of this approach in various clinical scenarios. Nonoperative management was recommended only for patients achieving complete clinical response CCR)after total neoadjuvant therapy TNT. Total mesorectal excision TME was advised when CCR was not achieved (primary TME), following residual cancer after Limited Local Excision LLE (completion TME), or after tumor recurrence/regrowth post-LLE or watchful waiting WW (salvage TME). This study examines treatment outcomes following primary or salvage TME in these biologically unfavorable cases.

Methods/Interventions: Each …

Comparison Of Magnetic Resonance Imaging (Mri) And Endoluminal Endoscopic Ultrasound (Eus) For Restaging Rectal Cancer After Neoadjuvant Chemotherapy, Judy Sheffeh, Amr Aref, Mohammed Barawi, Amer Alame, Amer Zeni, Ernesto R. Drelichman, Jasneet S. Bhullar

Conference Presentation Abstracts

Purpose/Background: Given the high incidence and mortality of rectal cancer, accurate staging and restaging are crucial for guiding optimal interventions. However, no consensus exists on the best imaging modality for restaging after neoadjuvant chemoradiotherapy. This study aims to compare MRI and EUS in the restaging of rectal cancer following neoadjuvant chemoradiotherapy.

Methods/Interventions: We conducted a prospective observational study and enrolled patients with rectal cancer. EUS and MRI were performed at diagnosis for initial staging and repeated after neoadjuvant chemotherapy and chemoradiotherapy for restaging. A total of 43 patients were enrolled, with 25 patients (10 males, 15 females) with rectal cancer …

Real-World Management Of High-Risk Prostate Cancer Post-Radical Prostatectomy: Insights From A Regional Quality Collaborative, Aaron R. Hochberg, Annie H. Ho, Rasheed A. M. Thompson, Matthew B. Buck, Costas D. Lallas, Christine Ibilibor, Jeffrey J. Tomaszewski, Serge Ginzburg, Andres Correa, Robert Uzzo, Marc C. Smaldone, John F. Danella, Thomas J. Guzzo, Daniel J. Lee, Laurence Belkoff, Jeffrey Walker, Jay D. Raman, Roderick K. Clark, Adam Reese, Bruce Jacobs, Thomas Jang, Keith J. Kowalczyk, Meghan Smith, Mihir S. Shah

Department of Urology Faculty Papers

Background/Objectives: Data from clinical trials showing the non-inferiority of early salvage radiotherapy were recently incorporated into societal guideline statements. However, questions remain regarding ideal prostate-specific antigen (PSA) criteria for salvage, and how to apply these findings to pathologic lymph node-positive (pN+) disease. We investigated variance in management of clinically localized prostate cancer found to have high-risk features after radical prostatectomy. Methods: We retrospectively identified patients from May 2015 to January 2024 utilizing a multi-institutional, regional collaborative database. The primary outcome was identifying factors associated with the receipt of adjuvant versus salvage therapy. Factors associated with secondary treatment were assessed via …