Radiation Medicine Commons^™

Clinical Experience Of Exactrac To Guide Six Degree Of Freedom Fiducial Marker Based Patient Positioning For Hypo-Prostate Fractionation, R Sandhu, C Knill, B Loughery, L Lin, Z Seymour

Conference Presentation Abstracts

Purpose: ExacTrac is clinically used for inter- and intra- fraction shift corrections for hypofractionated prostate patients by registering to implanted fiducial markers. ExacTrac corrections for thirty-three prostate patients were collated and analyzed. Methods: ExacTrac shifts were exported for prostate patients (140 total fractions) who were treated with two 180° partial arcs with beam-on time less than 60seconds/arc. Prior to each treatment fraction, a cone beam computed tomography (CBCT) image was acquired to verify bladder and rectal filling against simulation. Following CBCT, ExacTrac was used for initial prostate localization and shifts were applied using a 6 degree-of-freedom (6D) couch. Following initial …

Development Of A Collision Model For Advanced Proton Treatment Planning And Delivery, Shupeng Chen, Lewei Zhao, Weili Zheng, An Qin, Rohan Deraniyagala, Xuanfeng Ding

Conference Presentation Abstracts

Purpose: A major barrier to implementing advanced proton therapy delivery techniques, such as proton arc/4pi delivery is the unknown characteristics of the collision zones, i.e., the combinations of couch and gantry angles that result in a mechanical collision between the gantry and couch or patient. This study aims to develop a collision model for the determination of patient-specific collision zones to enable safe and deliverable noncoplanar proton therapy treatment planning. Methods: The detailed geometric parameters of the treatment machine including the nozzle, the snout, and the size and the location of the range shifter were measured from an IBA Proteus …

Commissioning And Validation Of A Monte Carlo Algorithm For Spine Stereotactic Radiosurgery, C Knill, R Sandhu, B Loughery, L Lin, R Halford, D Drake, M Snyder

Conference Presentation Abstracts

Purpose: A 6FFF Monte Carlo (MC) dose calculation algorithm was commissioned for spine stereotactic radiosurgery (SRS) planning on the Versa HD. Initial model generation, validation, and ensuing model tuning will be presented. Methods: The model was generated by the manufacturer, Brainlab, using both in-air and in-water commissioning measurements of field sizes between 6mm and 400mm on the Versa HD. Initial model validation was performed by simulating a water tank in the planning system, calculating commissioning fields, and comparing calculations to measured data. Model accuracy was quantified for output factors, PDDs, profile sizes, and profile penumbras. Nine previously treated Spine SRS …

A Novel Ultra-High Dose Rate Proton Therapy Technology: Spot-Scanning Proton Arc Therapy Flash (Splash), Gang Liu, Lewei Zhao, Xiaoqiang Li, S Zhang, S Dai, X Lu, Xuanfeng Ding

Conference Presentation Abstracts

Purpose: The flash dose rate on the order of 40 Gy/s has the potential to spare normal tissue with iso-effective tumor growth delay. Meanwhile, the spot-scanning proton arc therapy(SPArc), demonstrated its superior dosimetric conformity and plan robustness compared to the conventional intensity modulated proton therapy(IMPT). To take the full advantage of flash dose rate and the high dose conformity, we introduce a novel optimization and delivery technique, SPArc FLASH (SPLASH). Methods: SPLASH framework was implemented in an open-source proton planning platform (matRad). It optimizes the spot moniter unit(MU) weighting and cyclotron beam current per spot simultaneously. More specifically, it simultaneously …

During-Treatment Imaging Feasibility For Intrafraction Stereotactic Spine Treatment Evaluations, M Liu, D Drake, D Lack, M Sigler, J Sliwinski, K Barton, D To, I Grills, J Liang

Conference Presentation Abstracts

Purpose: On Elekta linacs, cone-beam CTs (CBCT) can be acquired during VMAT delivery to monitor intrafraction motion during treatment. Stereotactic spine treatments can be lengthy, increasing patient motion likelihood during treatment. We evaluated during-treatment CBCT (DT-CBCT) feasibility to assess patient motion for stereotactic spine treatments in place of a mid-treatment CBCT. Methods: CBCTs from seven spine treatments were analyzed retrospectively. Various fractionation schemes were used (16-25Gy delivered in 1-5 fractions). All plans contained two VMAT arcs of 2209.5-13,332.4 MUs with treatment times of 7-58 minutes. Projections from pre-correction CBCTs were combined with post-correction CBCT to simulate patient motion (1cm, 2 …

Evaluation Of 4pi Arc Positioning For Cranial Vmat Srs In Elements, B Loughery, C Knill, R Sandhu, L Lin, Z Seymour

Conference Presentation Abstracts

Purpose: Brainlab’s Elements Cranial VMAT (CVMAT) v3.0 introduces a 4Pi optimization that includes automated gantry and couch positioning alongside collimator optimization. In contrast, v1.5 uses a fixed collimator angle and predefined templates for gantry and couch angles that are manually modified by the planner. This study evaluates the 4Pi generated plans for clinical acceptability in terms of plan quality and delivery accuracy on a VersaHD. Methods: We chose a recent sample of 9 clinical plans that represent our catalog of target locations, fractionation schemes, and target sizes. Cases were replanned in CVMAT v3.0 using 4Pi optimization. These plans were evaluated …

Financial Toxicity Tumor Board: A Multi-Disciplinary Team Activity Required In Low And Middle-Income Countries (Lmic), Ahmed Nadeem Abbasi, Sohail Rasool, Laraib Khan

Department of Radiation Oncology

No abstract provided.

In-Phantom Film Measurements Of Two Treatment Planning Systems For Single-Fraction Spine Sbrt, Michael J. Taylor

LSU Master's Theses

Purpose: Treatment planning accuracy for spine stereotactic body radiation therapy (SBRT) varies depending on the dose calculation algorithm utilized in the treatment planning system (TPS). This project compared the end-to-end accuracy between spine SBRT plans calculated in a convolution-superposition based TPS (TPS_CS) and Monte Carlo based TPS (TPS_MC) with radiochromic film measurements. The hypothesis was that TPS_MC would calculate the dose gradient in the critical region between the vertebral body and the spinal cord more accurately than TPS_CS.

Methods: Single-fraction spine SBRT treatments following RTOG 0631 and local institutional guidelines were planned in …

Evaluating The Impact Of Software Distortion Correction On Target Doses In Cranial Stereotactic Radiosurgery, Sharjil Shamim, Zachary Seymour

Posters

INTRODUCTION
Brainlab’s Elements suite proposed a novel MR distortion correction method based on CT imaging. This involves registration of sub-volumes from MR imaging to generate single continuous deformation field maps, creating a corrected MR image set. No literature currently exists studying the impact of software correction on target dose for cranial stereotactic radiosurgery. In this study, we aim to evaluate the impact of Brainlab distortion correction on radiation target dose compared to original treatment plans without distortion correction.

Development Of A Deep Neural Network For Synthesis Of Non-Contrast Cranial T1-Weighted Magnetic Resonance Imaging, Agueda M. Taylor, Evan Porter, Thomas Guerrero

Posters

INTRODUCTION
Although 122 out of 1000 people in the US have MRI’s done each year, there are over 4 million with contraindications that subsequently forgo the diagnostic benefits. Studies in recent years have implemented artificial intelligence (AI) algorithms such as deep neural networks (DNN) for production of synthetic medical imaging. The goals of this project are to develop a DNN, specifically a Generative Adversarial Network (GAN) that will predict synthetic Cranial T1 Weighted MRI from non-contrast CT, and to evaluate the model quality.

Fluoroscopic Demonstration Of Thoracic Tumor Immobilization With High Frequency Percussive Ventilation, Cristian Solano, Ina M. Sala, Beverly Maurer, Ronald Levitin, Thomas M. Guerrero

Posters

INTRODUCTION
High frequency percussive ventilation (HFPV) is a novel immobilization technique that utilizes high frequency low tidal volume ventilation to produce endotracheal percussion. In a previous departmental study of chest wall motion immobilization, it was found that volunteers were able to tolerate HFPV for varying lengths of time – from a few to tens of minutes. By investigating a novel process to immobilize the chest wall, and thus thoracic tumors, it can allow for more localized radiation delivery and reduction of healthy tissue irradiation.

The Prognostic Significance Of Glucose-6-Phosphate Dehydrogenase As A Biomarker In Head And Neck Squamous Cell Carcinomas Treated With Conventional Chemoradiation, Kenneth H. Barker, Barbara L. Pruetz, Jessica D. Arden, Thomas J. Quinn, George D. Wilson

Posters

INTRODUCTION
The prognosis of patients with head and neck squamous cell carcinoma (HNSCC) treated with chemoradiation can be predicted using p16 as a surrogate biomarker of Human Papilloma Virus (HPV) status, but a subset of patients continues to do poorly despite a positive or negative p16 status. This project attempted to identify another biomarker, glucose-6-phosphate dehydrogenase (G6PD) as a marker for prognosis in HNSCC patients. Radiation induces oxidative damage to destroy tumor cells, and G6PD is a key enzyme involved in protecting cells from oxidative damage. The goal of this project was to identify a prognostic biomarker that would aid …

Functional Lung Segmentation From Computed Tomography Images Using Deep Learning, Duyen M. Quach, Evan Porter, Thomas M. Guerrero

Posters

INTRODUCTION
Functional avoidance treatment planning allows radiation oncologists to intentionally minimize radiation dose to higher-functioning lung areas while favoring radiation dose towards lower-functioning regions. This treatment planning method has been shown to reduce pulmonary toxicity for patients receiving radiation therapy. Functional lung information, traditionally ventilation or perfusion SPECT scans, is required to plan for functional avoidance.

Atr-Mediated Cd47 And Pd-L1 Upregulation Restricts Radiotherapy-Induced Immune Priming And Abscopal Responses In Colorectal Cancer, Cheng-En Hsieh, Cheng-En Hsieh

Dissertations & Theses (Open Access)

Radiotherapy of colorectal cancer (CRC) can prime adaptive immunity against tumor-associated antigen (TAA)-expressing CRC cells systemically. However, incidences of abscopal tumor remission are extremely rare, and the post-irradiation immune escape mechanisms in CRC remain elusive. We report that CRC cells utilize a common DNA repair signaling pathway — ATR/Chk1/STAT3 — to upregulate both CD47 and PD-L1 in response to radiotherapy, which through engagement of SIRPα and PD-1 suppresses the capacity of antigen-presenting cells to phagocytose them thereby preventing TAA cross-presentation and innate immune activation. This post-irradiation CD47 and PD-L1 upregulation can be observed across various human solid tumor cells. Concordantly, …

Feasibility Of Utilizing Spot-Scanning Proton Arc (Sparc) Therapy For Whole Lung Irradiation, Lewei Zhao, Gang Liu, An Qin, Di Yan, Craig Stevens, Xiaoqiang Li, Rohan Deraniyagala, Xuanfeng Ding

Conference Presentation Abstracts

Purpose or Objective We reported the first feasibility study of utilizing spot-scanning arc therapy (SPArc) whole lung irradiation for a pediatric patient to reduce cardiac toxicity. Materials and Methods A 13 year-old patient with metastatic Ewing sarcoma treated with Volumetric Modulated Arc Therapy (VMAT) in our institution was selected (Figure 1A). The clinical VMAT plan used three 360-deg arcs with 6 MV based on the Elekta HD. Intensity Modulated Proton Therapy (IMPT) plan was generated using 2 iso and 4 treatment fields (Figure 1B) based on the single field optimization approach in a clinical treatment planning system (TPS) (RayStation version …

Feasibility Of Acute Hematologic Toxicity Model-Based Patient Selection For Proton Beam Therapy, P Liu, X Cao, X Gao, S Shang, J Liu, Z Wang, Xuanfeng Ding

Conference Presentation Abstracts

Purpose or Objective To investigate the potential clinical benefit of utilizing IMPT to reduce acute hematologic toxicity for locally advanced nonsmall cell lung cancer (NSCLC) patients and explore the feasibility of a model-based patient selection approach via the normal tissue complication probability (NTCP). Materials and Methods Twenty patients with locally advanced NSCLC were enrolled.[ld1] Volumetric modulated arc photon therapy (VMAT) and intensity-modulated proton therapy (IMPT) plans were generated with a prescription dose of 60 Gy in 30 fractions. A wide range of cases with varied tumor size, location, stations of metastatic lymph nodes were selected to represent the general cancer …

Integration Of Biomedical Imaging And Translational Approaches For Management Of Head And Neck Cancer, Abdallah Mohamed, Abdallah Mohamed

Dissertations & Theses (Open Access)

The aim of the clinical component of this work was to determine whether the currently available clinical imaging tools can be integrated with radiotherapy (RT) platforms for monitoring and adaptation of radiation dose, prediction of tumor response and disease outcomes, and characterization of patterns of failure and normal tissue toxicity in head and neck cancer (HNC) patients with potentially curable tumors. In Aim 1, we showed that the currently available clinical imaging modalities can be successfully used to adapt RT dose based-on dynamic tumor response, predict oncologic disease outcomes, characterize RT-induced toxicity, and identify the patterns of disease failure. We …

Mri-Based Synthetic Ct Images For Impt Treatment Planning Of Nasopharyngeal Carcinoma Patients, Shupeng Chen, Y Peng, Y Liu, C Zhao, X Deng, An Qin, Di Yan, Craig Stevens, Rohan Deraniyagala, Xuanfeng Ding

Conference Presentation Abstracts

Purpose or Objective To investigate the feasibility of using an MRI-based synthetic CT image (SCT) generated via a generative adversarial network (GAN) for intensity-modulated proton therapy (IMPT) treatment planning of nasopharyngeal carcinoma (NPC) patients. Materials and Methods T1-weighted MR images and paired CT (PCT) images were obtained from 158 NPC patients with radiotherapy immobilization. Deformable image registration was performed between each MR and PCT image for each patient to create an MR-CT pair. Thirteen pairs were randomly chosen as independent test sets and the remaining 145 pairs (10 for validation and 135 for training) were used to build a conditional …

Contralateral Control Rate With Unilateral Proton Beam Radiotherapy For Oropharyngeal Scc: A Multi-Institutional Prospective Study From The Proton Collaborative Group, Aleksander Vayntraub, Thomas Quinn, John Chang, Noah Kalman, Sanford Katz, James Urbanic, Arpi Thukral, Jason Molitoris, Craig Stevens, Rohan Deraniyagala

Conference Presentation Abstracts

Introduction: Select patients with oropharyngeal SCC are candidates for unilateral radiation therapy. We sought to investigate if ipsilateral targeting leads to increased contralateral recurrences. Methods: We queried the PCG database for patients treated with unilateral proton RT for head and neck SCC from 2015 – 2020 at 12 institutions. DICOMs were evaluated to ensure dose delivered matched a unilateral proton treatment plan. Demographic, clinical and pathological, toxicity and dosimetry information were compiled. Results: We found 43 cases treated with unilateral proton RT. 94% (n¼16) of recurrent cases received prior radiation. Oropharyngeal sites included tonsillar fossa (n¼32), and base of tongue …

The First Modeling Of The Spot-Scanning Proton Arc(Sparc) Delivery Sequence And Investigating Its Efficiency Improvement, Xuanfeng Ding, Gang Liu, Lewei Zhao, Rohan Deraniyagala, Craig Stevens, Di Yan, Xiaoqiang Li

Conference Presentation Abstracts

Purpose: Introduce an experimental approach to model a precise prototype arc system and quantitatively assess its efficiency improvement in the routine proton clinical operation. Methods: The SPArc delivery sequence model(DSMSPArc) includes two kinds of parameters:(1) mechanical parameters. (2) irradiation parameters. Log files and an independent gantry inclinometer were used to derive the irradiation parameters through a series of test plans. The in-house DSMSPArc was established by fitting both mechanical and irradiation parameters. Eight SPArc plans from different disease sites were used to validate the model’s accuracy. To assess the treatment efficiency improvement, the DSMSPArc was used to simulate the SPArc …