Radiation Medicine Commons^™

Reirradiation Treatment Effects In The Clinic (Retec) Proposal - Proof Of Concept Based On Spinal Cord Dose Tolerance For Reirradiation With Stereotactic Body Radiotherapy, Jimm Grimm, Anand Mahadevan, Olusola Obayomi-Davies, Scott G. Soltys, Arjun Sahgal, Kristin J. Redmond, Michael T. Milano, Wolfgang A. Tomé, Kenneth Brooks, Scott Dodd, John Austin Vargo, Gopal Subedi, Jinyu Xue, Bisher Ebid, Felix Ehret, Byung-Han Andrew Rhieu, Christoph Fürweger, Rachel Grimm, Alexander Muacevic, Vitali Moiseenko, Shalom Kalnicki, Mark Mclaughlin, Lawrence R. Kleinberg, John R. Adler, Iris C. Gibbs

College of Health Professions Faculty Papers

BACKGROUND: Since the inception of spinal radiosurgery decades ago, the factors influencing spinal cord recovery have remained unclear. Elucidating these factors would aid in reirradiation planning and delivery. We describe modeling reirradiation normal tissue complication probabilities (NTCP) from compiled published data, akin to the collaborative Quantitative Analysis of Normal Tissue Effects in the Clinic (QUANTEC) and High Dose per Fraction, Hypofractionated Treatment Effects in the Clinic (HyTEC) projects.

PURPOSE: Simple dose-time recovery factors for the spinal cord serve as a basis to propose the Reirradiation Treatment Effects in the Clinic (ReTEC) project. ReTEC aims to define human organ recovery factors …

Computed Tomography For Four-Dimensional Dose Calculation: Effect Of Detector Array Length, Inhwan Yeo, Qianyi Xu

Department of Radiation Oncology Faculty Papers

PURPOSE: Four-dimensional computed tomography (4DCT) is susceptible to a geometrical error when respiration changes upon patient shift. 4DCT using 16-cm detector arrays, not needing the shift, has been shown to improve geometrical accuracy, compared with a conventional 4DCT (4-cm array), albeit with some Hounsfield unit discrepancies. The 4DCTs were validated for 4D planning.

MATERIALS AND METHODS: A lung-mimicking phantom containing a spherical target with ten respiratory traces and three tumor-shaped targets with their traces was respectively imaged when, to each of the ten-positions/phases, the lung was moved (1) step-wisely by helical scan at each movement (ground truth; 4DCT_GT), …

Evaluation Of The Intempo Path Set For Cyberknife Prostate And Lung Sbrt: A Single-Institution Experience, Yingcui Jia, Lei Fu, Shari Rudoler, Eric Gressen, Yevgeniy Vinogradskiy, Qianyi Xu

Department of Radiation Oncology Faculty Papers

PURPOSE: The InTempo adaptive imaging system is an important component of the Accuray CyberKnife System, designed to enhance the system's ability to track and correct tumor motion during treatment. However, a limitation of this feature is the reduction of available nodes for treatment planning. The impact of a reduced number of nodes on the quality of InTempo-based treatment plans has not previously been evaluated. This retrospective study aims to compare the dosimetry of CyberKnife plans with and without The InTempo path set for both prostate and lung stereotactic body radiotherapy (SBRT).

METHODS: This study included twelve consecutive prostate SBRT patients …

Clinical Test Cases For Commissioning, Qa, And Benchmarking Of Model-Based Dose Calculation Algorithms In 1⁹2ir Hdr Gynecologic Tandem And Ring Brachytherapy, Vasiliki Peppa, Maude Robitaille, Fatemeh Akbari, Shirin Enger, Rowan Thomson, Firas Mourtada, Gabriel Fonseca

Department of Radiation Oncology Faculty Papers

PURPOSE: To develop clinically relevant test cases for commissioning Model-Based Dose Calculation Algorithms (MBDCAs) for ¹⁹²Ir High Dose Rate (HDR) gynecologic brachytherapy following the workflow proposed by the TG-186 report and the WGDCAB report 372.

ACQUISITION AND VALIDATION METHODS: Two cervical cancer intracavitary HDR brachytherapy models were developed based on a real patient, using either uniformly structured regions or realistic segmentation. The patient's computed tomography (CT) images were processed, converted to a series of digital imaging and communications in medicine (DICOM) CT images, and imported into two treatment planning systems (TPSs), the Oncentra Brachy and BrachyVision. The original segmentation …

A Feasibility Study Of Sexual Organ-Dose Sparing Volumetric Modulated Arc Therapy In Female Low Rectal Cancer Patients Treated With Three-Dimensional Conformal Radiation Therapy, Margaret Downes, Victoria Olsen, Andre Williams, Rendi Sheu, Maria Thor, Lucy Greenwald, Vishruta Dumane, Kristin Hsieh, Ayesha Ali, Orly Morgan, Michael Buckstein, Deborah Marshall

Department of Radiation Oncology Faculty Papers

BACKGROUND: Sexual dysfunction is a significant toxicity of pelvic radiation therapy (RT) for female rectal cancer patients and may be more common with intensity-modulated techniques compared to three-dimensional conformal radiation therapy (3D-CRT). However, limited research has evaluated dose sparing of female sexual organs at risk (OARs), particularly erectile tissues that are critical for sexual function.

PURPOSE: This feasibility study aimed to demonstrate the practicality of contouring and sparing female sexual OARs in rectal cancer RT by generating sexual organ-sparing volumetric modulated arc therapy (SO-VMAT) plans from a small 3D-CRT cohort and comparing dose distributions to guide future planning.

METHODS: Nine …

From Standard To Stratified: Modeling Ntcp And Ear To Personalize Daily Mv-Cbct In Radiotherapy., Duong Thanh Tai, Luong Tien Phat, Tran Trung Kien, Duong Tuan Linh, Nguyen Ngoc Anh, Nguyen Quang Hung, Peter Sandwall, Parham Alaei, David Bradley, James C L Chow

Oncology Articles

PURPOSE: To evaluate the cumulative radiobiological impact of daily megavoltage cone-beam computed tomography (MV-CBCT) imaging dose based on normal tissue complication probability (NTCP) and excess absolute risk (EAR) of secondary malignancies among radiotherapy patients treated for breast, pelvic, and head & neck cancers. This study investigated whether MV-CBCT imaging dose warrants protocol personalization according to patient age, anatomical treatment site, and organ-specific radiosensitivity.

METHODS: This retrospective study included cohorts of breast (n = 30), pelvic (n = 17), and head & neck (n = 20) cancer patients undergoing radiotherapy with daily MV-CBCT. Imaging dose distributions employing two common MV-CBCT protocols …

Fast And Accurate Measurement Of Small Field Dosimetry Using A Novel Scintillation Detector, Yiding Han, Jingzhu Xu, Yao Hao, Baozhou Sun

Faculty, Staff and Students Publications

Background: The most used instruments for small-field dosimetry have notable limitations, including the need for correction of output factors, limited scanning speeds, and challenges in alignment for percentage depth dose (PDD) measurements, particularly for extremely small fields. However, plastic scintillation detectors (PSDs) are an attractive alternative for small-field dosimetry due to their correction-free nature, linear dose response, and fast response time.

Purpose: This study evaluates the robustness and accuracy of the dosimetric measurements using a new water-equivalent PSD in small-field dosimetry. The study also aims to report accurate measurements of output factors, profiles, and an indirect method for measuring PDD …

Enhancing Cyberattack Resiliency Through The Radiotherapy Backup And Recovery Dashboard Tool, Justin Pijanowski, Eric Nguyen, Yasin Abdulkadir, Justin Hink, Yevgeniy Vinogradskiy, James Lamb

Department of Radiation Oncology Faculty Papers

PURPOSE: Radiation Oncology departments impacted by recent cyberattacks were unable to access data backups or their Record and Verify (R&V) system and therefore faced challenges to resume patient treatments in a timely manner. We present a novel software tool that backs-up critical radiotherapy treatment information and displays essential information for on-treatment patients in an intuitive and accessible dashboard allowing clinics to continue radiotherapy treatments. The purpose of this report is to describe implementation details, challenges, and share open-source code to facilitate radiation oncology clinics' efforts to develop tools to improve cyberattack resiliency.

METHODS: The Radiotherapy Backup and Recovery Dashboard Tool …

Evaluation Of Image Quality In Mobile Cone-Beam Ct With Dose Modulation Using Automatic Exposure Control: A Phantom Study, Keita Okazaki, Wenchao Cao, Reza Taleei, Firas Mourtada, Jun Li, Karen Mooney, Pramila Rani Anne, Yingxuan Chen

Department of Radiation Oncology Faculty Papers

BACKGROUND: The integration of mobile cone-beam computed tomography (CBCT) into brachytherapy workflows offers clinical advantages such as immediate verification of applicator placement and adaptive treatment planning. These benefits require sufficient image quality to delineate applicators, target volumes, and organs at risk. A systematic evaluation of automatic exposure control (AEC) settings, radiation dose, and image quality is essential to ensure clinically acceptable imaging while minimizing patient exposure.

PURPOSE: This study evaluates the characteristics of AEC and its impact on image quality and radiation dose in a mobile CBCT system used for brachytherapy.

METHODS: The Elekta ImagingRing CBCT system was used to …

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 …

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 …

Evaluating Artifact-Free Four-Dimensional Computer Tomography With 16 Cm Detector Array, Inhwan Yeo, Wei Nie, Jiajin Fan, Mindy Joo, Michael Correa, Qianyi Xu

Department of Radiation Oncology Faculty Papers

PURPOSE: To evaluate a 16 cm-array axial four-dimensional computer tomography (4DCT) in comparison with a 4 cm-array 4DCT in the presence of respiration irregularity.

METHOD: Ten traces of lung tumor motion from CyberKnife treatments were imported to move the lung cylinder, containing a spherical target, of a phantom. Images were acquired for the lung that moved to each of the 10-positions/phases (1) step-wisely by nominal helical scan at each movement (ground truth), (2) continuously by 4D scan with the 16 cm array, and (3) the same with the 4 cm array, involving table shift. Irregularities, consisting of baseline shift and/or …

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 …

Three-Dimensional Deep Learning Normal Tissue Complication Probability Model To Predict Late Xerostomia In Patients With Head And Neck Cancer, Hung Chu, Suzanne P M De Vette, Hendrike Neh, Nanna M Sijtsema, Roel J H M Steenbakkers, Amy Moreno, Johannes A Langendijk, Peter M A Van Ooijen, Clifton D Fuller, Lisanne V Van Dijk

Faculty, Staff and Student Publications

Purpose: Conventional normal tissue complication probability (NTCP) models for patients with head and neck cancer are typically based on single-value variables, which, for radiation-induced xerostomia, are baseline xerostomia and mean salivary gland doses. This study aimed to improve the prediction of late xerostomia by using 3-dimensional information from radiation dose distributions, computed tomography imaging, organ-at-risk segmentations, and clinical variables with deep learning (DL).

Methods and materials: An international cohort of 1208 patients with head and neck cancer from 2 institutes was used to train and twice validate DL models (deep convolutional neural network, EfficientNet-v2, and ResNet) with 3-dimensional dose distribution, …

Novel 3d Printed Universal Conical Holder For Eye Plaque Quality Assurance, Wentao Wang, Jacqueline Emrich, Firas Mourtada

Department of Radiation Oncology Faculty Papers

PURPOSE: For the custom-built construction of eye plaques, the iodine (I-125) seeds of different source strengths are recycled in our eye plaque program. To return I-125 seeds to the correct lot, we developed a novel 3D-printed conical plaque QA holder for relative assay for eye plaques.

MATERIALS AND METHODS: A universal 3D-printed conical plaque holder was designed to accommodate six plaque sizes and fit reproducibly in a well-type dose calibrator. A reproducibility test was used to compare the plaque placement consistency in the holder versus without the holder. Plaque assays were performed for assembled plaques both before implant and after …

Multi-Institution Single Geometry Plan Complexity Characteristics Based On Iroc Phantoms, Vimal Desai, Zacariah Labby, Wesley Culberson, Larry Dewerd, Stephen Kry

Department of Radiation Oncology Faculty Papers

BACKGROUND: Clinical intensity modulated radiation therapy plans have been described using various complexity metrics to help identify problematic radiotherapy plans. Most previous studies related to the quantification of plan complexity and their utility have relied on institution-specific plans which can be highly variable depending on the machines, planning techniques, delivery modalities, and measurement devices used. In this work, 1723 plans treating one of only four standardized geometries were simultaneously analyzed to investigate how radiation plan complexity metrics vary across four different sets of common objectives.

PURPOSE: To assess the treatment plan complexity characteristics of plans developed for Imaging and Radiation …

Real World Clinical Experience Using Daily Intelligence-Assisted Online Adaptive Radiotherapy For Head And Neck Cancer, Philip Blumenfeld, Eduard Arbit, Robert Den, Ayman Salhab, Tal Falick Michaeli, Marc Wygoda, Yair Hillman, Raphael Pfeffer, Marcel Fang, Yael Misrati, Noam Weizman, Jon Feldman, Aron Popovtzer

Department of Radiation Oncology Faculty Papers

Background

Adaptive radiation therapy (ART) offers a dynamic approach to address structural and spatial changes that occur during radiotherapy (RT) for locally advanced head and neck cancers. The integration of daily ART with Cone-Beam CT (CBCT) imaging presents a solution to enhance the therapeutic ratio by addressing inter-fractional changes.

Methods

We evaluated the initial clinical experience of daily ART for patients with head and neck cancer using an online adaptive platform with intelligence-assisted workflows on daily CBCT. Treatment included auto-contour and structure deformation of Organs at Risk (OARs) and target structures, with adjustments by the treating physician. Two plans were …

Clinical And Dosimetric Results Of Proton Or Photon Radiation Therapy For Large (>5 Cm) Hepatocellular Carcinoma: A Retrospective Analysis, Rodney Cheng-En Hsieh, Ching-Hsin Lee, Hsiao-Chieh Huang, Shu-Wei Wu, Chen-Yu Chou, Sheng-Ping Hung, Chao-Wei Lee, Sunil Krishnan, Bhanu Prasad Venkatesulu, Jin-Chiao Lee, Yung-Chih Chou, Kun-Ming Chan, Po-Ting Lin, Wei-Chen Lee, Chen-Chun Lin, Shen-Yen Lin, Ji-Hong Hong

Faculty, Staff and Student Publications

Purpose: Our purpose was to report the clinical and dosimetric attributes of patients with large unresectable hepatocellular carcinoma (HCC) undergoing proton or photon radiation therapy.

Methods and materials: We retrospectively analyzed the outcomes and dosimetric indices of 159 patients with >5 cm nonmetastatic HCC who underwent definitive radiation therapy using either protons (N = 105) or photons (N = 54) between 2014 and 2018. Additional photon plans were performed in the 105 proton-treated patients using the same dose prescription criteria for intragroup dosimetric comparison.

Results: After a median follow-up of 47 months, patients with biologically effective dose (BED10) ≥ 75 …

Characterizing The Interplay Of Treatment Parameters And Complexity And Their Impact On Performance On An Iroc Imrt Phantom Using Machine Learning, Hunter Mehrens, Andrea Molineu, Nadia Hernandez, Laurence Court, Rebecca Howell, David Jaffray, Christine B Peterson, Julianne Pollard-Larkin, Stephen F Kry

Faculty, Staff and Student Publications

AIM OF THE STUDY: To elucidate the important factors and their interplay that drive performance on IMRT phantoms from the Imaging and Radiation Oncology Core (IROC).

METHODS: IROC's IMRT head and neck phantom contains two targets and an organ at risk. Point and 2D dose are measured by TLDs and film, respectively. 1,542 irradiations between 2012-2020 were retrospectively analyzed based on output parameters, complexity metrics, and treatment parameters. Univariate analysis compared parameters based on pass/fail, and random forest modeling was used to predict output parameters and determine the underlying importance of the variables.

RESULTS: The average phantom pass rate was …

High-Dose Once-Daily Thoracic Radiotherapy In Limited-Stage Small-Cell Lung Cancer: Calgb 30610 (Alliance)/Rtog 0538, Jeffrey Bogart, Xiaofei Wang, Gregory Masters, Junheng Gao, Ritsuko Komaki, Laurie E Gaspar, John Heymach, James Bonner, Charles Kuzma, Saiama Waqar, William Petty, Thomas E Stinchcombe, Jeffrey D Bradley, Everett Vokes

Faculty, Staff and Student Publications

PURPOSE: Although level 1 evidence supports 45-Gy twice-daily radiotherapy as standard for limited-stage small-cell lung cancer, most patients receive higher-dose once-daily regimens in clinical practice. Whether increasing radiotherapy dose improves outcomes remains to be prospectively demonstrated.

METHODS: This phase III trial, CALGB 30610/RTOG 0538 (ClinicalTrials.gov identifier: NCT00632853), was conducted in two stages. In the first stage, patients with limited-stage disease were randomly assigned to receive 45-Gy twice-daily, 70-Gy once-daily, or 61.2-Gy concomitant-boost radiotherapy, starting with either the first or second (of four total) chemotherapy cycles. In the second stage, allocation to the 61.2-Gy arm was discontinued following planned interim toxicity …

Applicability And Usage Of Dose Mapping/Accumulation In Radiotherapy, Martina Murr, Kristy K Brock, Marco Fusella, Nicholas Hardcastle, Mohammad Hussein, Michael G Jameson, Isak Wahlstedt, Johnson Yuen, Jamie R Mcclelland, Eliana Vasquez Osorio

Faculty, Staff and Student Publications

Dose mapping/accumulation (DMA) is a topic in radiotherapy (RT) for years, but has not yet found its widespread way into clinical RT routine. During the ESTRO Physics workshop 2021 on "commissioning and quality assurance of deformable image registration (DIR) for current and future RT applications", we built a working group on DMA from which we present the results of our discussions in this article. Our aim in this manuscript is to shed light on the current situation of DMA in RT and to highlight the issues that hinder consciously integrating it into clinical RT routine. As a first outcome of …

Deep Learning-Based Dose Prediction For Automated, Individualized Quality Assurance Of Head And Neck Radiation Therapy Plans, Mary P Gronberg, Beth M Beadle, Adam S Garden, Heath Skinner, Skylar Gay, Tucker Netherton, Wenhua Cao, Carlos E Cardenas, Christine Chung, David T Fuentes, Clifton D Fuller, Rebecca M Howell, Anuja Jhingran, Tze Yee Lim, Barbara Marquez, Raymond Mumme, Adenike M Olanrewaju, Christine B Peterson, Ivan Vazquez, Thomas J Whitaker, Zachary Wooten, Ming Yang, Laurence E Court

Faculty, Staff and Student Publications

PURPOSE: This study aimed to use deep learning-based dose prediction to assess head and neck (HN) plan quality and identify suboptimal plans.

METHODS AND MATERIALS: A total of 245 volumetric modulated arc therapy HN plans were created using RapidPlan knowledge-based planning (KBP). A subset of 112 high-quality plans was selected under the supervision of an HN radiation oncologist. We trained a 3D Dense Dilated U-Net architecture to predict 3-dimensional dose distributions using 3-fold cross-validation on 90 plans. Model inputs included computed tomography images, target prescriptions, and contours for targets and organs at risk (OARs). The model's performance was assessed on …

High Local Control And Low Ocular Toxicity Using Ultra-Low-Dose “Boom-Boom” Radiotherapy For Indolent Orbital Lymphoma, Sanjna Shelukar, Christian Fernandez, Zeynep Bas, Lydia Komarnicky, Sara E. Lally, Carol L Shields, Adam Binder, Pierluigi Porcu, Onder Alpdogan, Ubaldo Martinez-Outschoorn, Wenyin Shi

Department of Medical Oncology Faculty Papers

Background: The first line definitive treatment for early-stage indolent B-cell lymphoma is radiation therapy (RT). Due to the sensitivity of orbital structures to radiation, ultra-low-dose RT (4 Gy in 2 fractions, "boom-boom") has and been utilized as an attractive option for orbital lymphoma. In this retrospective study, we evaluated the outcome and toxicity of "boom-boom" RT for indolent orbital lymphoma with an emphasis on ophthalmologic toxicity.

Methods: This is a retrospective case series with 17 patients with orbital lymphoma who received boom-boom RT at a single tertiary referral center between January 2017 and June 2022. Medical records, imaging and radiation …

Fast Generation Of Lung Sbrt Plans With A Knowledge-Based Planning Model On Ring-Mounted Halcyon Linac, Justin Visak, Aaron Webster, Mark E. Bernard, Mahesh R. Kudrimoti, Marcus E. Randall, Ronald C. Mcgarry, Damodar Pokhrel

Radiation Medicine Faculty Publications

PURPOSE: To demonstrate fast treatment planning feasibility of stereotactic body radiation therapy (SBRT) for centrally located lung tumors on Halcyon Linac via a previously validated knowledge-based planning (KBP) model to support offline adaptive radiotherapy.

MATERIALS/METHODS: Twenty previously treated non-coplanar volumetric-modulated arc therapy (VMAT) lung SBRT plans (c-Truebeam) on SBRT-dedicated C-arm Truebeam Linac were selected. Patients received 50 Gy in five fractions. c-Truebeam plans were re-optimized for Halcyon manually (m-Halcyon) and with KBP model (k-Halcyon). Both m-Halcyon and k-Halcyon plans were normalized for identical or better target coverage than clinical c-Truebeam …

Predicting The Effect Of Indirect Cell Kill In The Treatment Of Multiple Brain Metastases Via Single-Isocenter/Multitarget Volumetric Modulated Arc Therapy Stereotactic Radiosurgery, Allison N. Palmiero, Denise Fabian, Marcus E. Randall, William St. Clair, Damodar Pokhrel

Radiation Medicine Faculty Publications

PURPOSE: Due to spatial uncertainty, patient setup errors are of major concern for radiosurgery of multiple brain metastases (m-bm) when using single-isocenter/multitarget (SIMT) volumetric modulated arc therapy (VMAT) techniques. However, recent clinical outcome studies show high rates of tumor local control for SIMT-VMAT. In addition to direct cell kill (DCK), another possible explanation includes the effects of indirect cell kill (ICK) via devascularization for a single dose of 15 Gy or more and by inducing a radiation immune intratumor response. This study quantifies the role of indirect cell death in dosimetric errors as a function of spatial patient setup uncertainty …

Conditional Survival Among Patients With Oropharyngeal Cancer Treated With Radiation Therapy And Alive Without Recurrence 5 Years After Diagnosis, Kristina R Dahlstrom, Juhee Song, Peter F Thall, Clifton D Fuller, Katherine A Hutcheson, Faye M Johnson, G Brandon Gunn, Jack Phan, Steven J Frank, William H Morrison, Renata Ferrarotto, David I Rosenthal, Erich M Sturgis, Adam S Garden

Faculty, Staff and Students Publications

BACKGROUND: Risk of recurrence among patients with oropharyngeal cancer (OPC) who survive 5 years is low. The goal of this study was to assess long-term survival of patients with OPC alive without recurrence 5 years after diagnosis.

METHODS: This study included newly diagnosed patients with OPC, who had been treated with radiation and were alive without recurrence 5 years after diagnosis. Overall survival (OS) probabilities beyond 5 years were estimated using the Kaplan-Meier method. Factors associated with OS were determined using Bayesian piecewise exponential survival regression. Standardized mortality ratios for all-cause death were estimated controlling for study year, age, and …

An Analytical Expression For R50% Dependent On Ptv Surface Area And Volume: A Cranial Srs Comparison, Dharmin D. Desai, Ellis Lee Johnson, Ivan L. Cordrey

Radiation Medicine Faculty Publications

The intermediate dose spill for a stereotactic radiosurgery (SRS) plan can be quantified with the metric R50%, defined as the 50% isodose cloud volume (V_IDC50%) divided by the volume of the planning target volume (PTV). By coupling sound physical principles with the basic definition of R50%, we derive an analytical expression for R50% for a spherical PTV. Our analytical expression depends on three quantities: the surface area of PTV (SA_PTV), the volume of PTV (V_PTV), and the distance of dose drop-off to 50% (Δr). The value of ∆r was obtained from a simple set …

A Novel And Clinically Useful Dynamic Conformal Arc (Dca)-Based Vmat Planning Technique For Lung Sbrt, Damodar Pokhrel, Justin Visak, Lana Sanford

Radiation Medicine Faculty Publications

PURPOSE: Volumetric modulated arc therapy (VMAT) is gaining popularity for stereotactic treatment of lung lesions for medically inoperable patients. Due to multiple beamlets in delivery of highly modulated VMAT plans, there are dose delivery uncertainties associated with small-field dosimetry error and interplay effects with small lesions. We describe and compare a clinically useful dynamic conformal arc (DCA)-based VMAT (d-VMAT) technique for lung SBRT using flattening filter free (FFF) beams to minimize these effects.

MATERIALS AND METHODS: Ten solitary early-stage I-II non-small-cell lung cancer (NSCLC) patients were treated with a single dose of 30 Gy using 3-6 non-coplanar VMAT arcs (clinical …

Outlier Identification In Radiation Therapy Knowledge-Based Planning: A Study Of Pelvic Cases., Yang Sheng, Yaorong Ge, Lulin Yuan, Taoran Li, Fang-Fang Yin, Qingrong Jackie Wu

Department of Radiation Oncology Faculty Papers

PURPOSE: The purpose of this study was to apply statistical metrics to identify outliers and to investigate the impact of outliers on knowledge-based planning in radiation therapy of pelvic cases. We also aimed to develop a systematic workflow for identifying and analyzing geometric and dosimetric outliers.

METHODS: Four groups (G1-G4) of pelvic plans were sampled in this study. These include the following three groups of clinical IMRT cases: G1 (37 prostate cases), G2 (37 prostate plus lymph node cases) and G3 (37 prostate bed cases). Cases in G4 were planned in accordance with dynamic-arc radiation therapy procedure and include 10 …