Radiation Medicine Commons^™

A Quantitative Investigation At Dose To Tissue When Using Physical Constraints Versus Biological Based Constraints In Pancreatic Carcinoma Patients, Kelly R. Alley

Culminating Experience Projects

Introduction

The purpose of this study was to compare dose to organs at risk as well as PTV coverage. Physical objectives, biological objectives, and a combination of the two were utilized to compare which technique provided the best coverage of the PTV while also preserving the greatest amount of healthy tissue.

Methods

Each randomly selected patient had three separate plans created for them. The first plan used only physical based constraints in the form of upper objectives. The second plan used only biological based constraints in the form of gEUD objectives. The third plan used a combination of both upper …

Development Of A Novel Rodent Model Of Radiation-Induced Implant Capsular Contracture, Tanya Delyzer

Electronic Thesis and Dissertation Repository

Radiation-induced implant capsular contracture is a challenging complication of post-mastectomy breast reconstruction. The objective of this thesis was to establish a novel rodent model that replicates the critical properties of this complication. Retired breeder female Sprague-Dawley rats underwent surgery with custom smooth silicone implants placed under the right 4^th mammary fat pad. Half these rats received 26Gy of ionizing radiation to the implant and fat pad. Radiated implants had both higher Baker grades of capsular contracture and Kumar scores denoting radiation-induced fibrosis. Irradiated capsules showed increased Masson’s trichrome staining and significantly higher hydroxyproline to total protein ratio compared to …

Tumor Vasculature Changes Before Or During Treatment To Predict Response To Systemic Therapy, Avinash Ramkissoon, Faria Ali, Thomas Vander Woude, Stephen Brown, James Ewing, Lisa Rogers

Medical Student Research Symposium

A diagnosis of non-small cell lung cancer (NSCLC) carries a grim prognosis, with 5-year survival rates of 25%. 25-30% of NSCLC patients have brain metastases at initial presentation, which carries an even worse prognosis. New systemic therapies such as targeted-therapies and immuno-therapies have potential to provide better outcomes, but are not without challenges. First, efficacy is limited to a subset of patients. Second, the blood-brain barrier limits penetration, which varies among patients. Third, toxicities can be considerable. Current practice involves waiting 3-6 months to follow-up and assess tumor response; however, by then, it is later than ideal to try other …

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 …

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 …

Variation In Molecularly Defined Prostate Tumor Subtypes By Self-Identified Race, Kevin H. Kensler, H. Lee Moffitt Cancer Center And Research Institute, Mohamed Alshalalfa, Bruce J. Trock, Stephen J. Freedland, Michael R. Freeman, Sungyong You, Brandon A. Mahal, Robert Den, Adam Dicker, R. Jeffrey Karnes, Eric A. Klein, Priti Lal, Yang Liu, Elai Davicioni, Walter Rayford, Kosj Yamoah, Timothy R. Rebbeck

Department of Radiation Oncology Faculty Papers

Background: Socioeconomic and health care utilization factors are major drivers of prostate cancer (PC) mortality disparities in the USA; however, tumor molecular heterogeneity may also contribute to the higher mortality among Black men. Objective: To compare differences in PC subtype frequency and genomic aggressiveness by self-identified race. Design, setting, and participants: Five molecular subtype classifiers were applied for 426 Black and 762 White PC patients in the Decipher Genomics Resource Information Database (GRID). Outcome measurements and statistical analysis: Differences in subtype frequency and tumor genomic risk (Decipher score >0.6) by race were evaluated using χ2 tests and multivariable-adjusted logistic regression …

An Evolutionary Algorithm Of The Spot Sparsity Optimization In Proton Arc Therapy, Lewei Zhao, Gang Liu, Xiaoqiang Li, Xuanfeng Ding

Conference Presentation Abstracts

Purpose: Spot-scanning Proton Arc (SPArc) plan normally contains thousands of spot numbers in which is the delivery time is proportional to the number of spots. It is critical to find an optimal SPArc with a fast delivery speed while maintaining a good plan quality. Thus, we developed a novel evolutionary algorithm to directly search the optimal spot sparsity solution in the balance of plan quality and beam delivery time (BDT). Methods: The planning platform included a plan quality objective, a selector and a generator. A selector was designed to filter or add the spot according to the expected spot number, …

Quantifying Copd Disease Severity With Ct-Derived Perfusion Imaging, A Nowacki, G Nair, Y Liu, C J. Galban, C Stevens, E Castillo

Conference Presentation Abstracts

Purpose: CT-derived perfusion (CTP) is a novel image processing modality that quantifies pulmonary perfusion from non-contrast inhale/exhale CT image pairs. While existing imaging markers for COPD primarily depend on morphological features or HU thresholding, CTP provides a quantitative marker of blood flow and has been shown to identify disease progression prior to the appearance structural abnormalities. In this study, we assess the potential utility of CTP as a disease severity marker for COPD. Methods: CTP was computed from high-resolution inhale-exhale CT scans for 785 patients with a Global Initiative for Obstructive Lung Disease (GOLD) score ranging from 0 to 4 …

Per-Fraction Deviation In Logfile Parameters Reported In A Single Vmat Arc, M Snyder, D To, D Drake, J Liang, D Lack

Conference Presentation Abstracts

Purpose: Measurement-based QA identifies large deviations between planned and delivered dose, but subtle—yet clinically unacceptable—deviations can pass through the conventional QA process unnoticed. Incorporating logfilebased information into pre-treatment QA should result in more robust QA overall, provided such information is stable across the entire treatment course. We present here a case-study of logfile stability to investigate the potential of logfiles as useful adjuncts in the QA process. Methods: We analyzed logfiles from six fractions of a VMAT plan delivered on an Elekta Infinity linac with an Agility MLC. To simplify the analysis, we considered a single 52 control point VMAT …

Mri-Based Synthetic Ct Images Generated Using 3d Conditional Gan For Impt Treatment Planning, Shupeng Chen, An Qin, Rohan Deraniyagala, Xuanfeng Ding, Y Peng, Y Liu, C Zhao, X Deng

Conference Presentation Abstracts

Purpose: To develop an advanced deep convolutional neural network architecture to generate synthetic CT (SCT) images from MR images for intensity-modulated proton therapy (IMPT) treatment planning of head and neck cancer patients. Methods: T1-weighted MR images and paired CT (PCT) images were obtained from 189 nasopharyngeal cancer (NPC) patients under radiotherapy immobilization. Deformable image registration was performed between MR and PCT images for each patient to create an MR-CT image pair. Thirteen pairs were randomly chosen as independent test sets and the remaining 176 pairs (14 for validation and 162 for training) were used to build two conditional generative adversarial …

Does Lung Function Imaging Modality Have A Dosimetric Impact On Functional Avoidance Treatment Planning: Assessment Using Prospective Clinical Trial Data, J Belardo, S Zhang, E Castillo, R Castillo, C Rusthoven, B Jones, M Miften, T Guerrero, I Grills, Y Chen

Conference Presentation Abstracts

Purpose: Functional avoidance radiotherapy proposes to use functional imaging to design treatment plans that reduce doses to functional regions of lung. Prospective data has shown that reducing doses to functional lung results in reduced pulmonary toxicity. Various lung function imaging modalities have been proposed for functional avoidance; however, there have been no studies evaluating whether using different imaging modalities results in dosimetrically different functional avoidance plans. The purpose of this study was to quantify the differences in treatment plans as a function of lung function imaging modality. Methods: 25 lung cancer patients enrolled on a prospective trial underwent nuclear medicine …

Evaluation Of Variables Predicting Pulmonary Function Test (Pft) Changes For Lung Cancer Patients Treated On A Prospective 4dct-Ventilation Functional Avoidance Clinical Trial, Nader Ghassemi, Richard Castillo, Edward Castillo, Bernard L. Jones, Moyed Miften, Brian Kavanaugh, Maria Werner Werner-Wasik, Ryan Miller, Julie Barta, Inga Grills, Thomas Guerrero

Conference Presentation Abstracts

Purpose: Functional avoidance radiotherapy uses functional imaging to reduce pulmonary toxicity by designing radiotherapy plans that reduce doses to the functional lung. A novel form of lung functional imaging uses 4DCT imaging to calculate 4DCT-based lung ventilation (4DCT-ventilation) maps. A phase-II, multi-center, prospective study of 4DCT-ventilation functional avoidance was completed. Pre and post-treatment pulmonary function tests (PFTs) were acquired in order to quantitatively assess pulmonary function change. The purpose of this study is to evaluate which factors predict for PFT changes for patients treated with 4DCT-ventilation functional avoidance radiotherapy. Methods: 56 patients with locally advanced lung cancer receiving radiotherapy were …

Real-Time Tracking Diaphragm Motion On During-Treatment Kv Cone Beam Projection Images Using Resnet50, J Liang, Q Liu, E Porter, D Yan

Conference Presentation Abstracts

Purpose: Diaphragm manifested on Cone Beam projection image has been used as surrogate to monitor lung tumor position. We propose a deep learning method to detect diaphragm apex position of the ipsilateral lung in real-time on KV projections acquired during Lung SBRT delivery. Methods: 7 hypo-lung SBRT patients with right lower lobe tumor were selected in this retrospective study. The imaging projection angle ranges from about -270 to 112 degrees. The right lung diaphragm apex was manually labeled as ground-truth on KV projections acquired during-treatment sessions with 899±167 projections per session. The backbone of our machine learning model is 50 …

Comparison Of Aperture Complexity Between Vmat Plans Using Conventionally Flattened (Ff) And Flattening-Filter-Free (Fff) Beams, Q Liu, J Liang

Conference Presentation Abstracts

Purpose: VMAT plans with high amount of complex apertures could lead to less confidence in dose calculation accuracy due to machine modelling and dose algorithm limitations. It was hypothesized that VMAT plans generated with FFF beams would result in more complex aperture shapes due to the non-flattened beam profile. The purpose of this study was to test this hypothesis by assessing various plan complexity metrics. Methods: Target and organ-at-risk structures were created on an anthropomorphic phantom in various sites: lung, prostate, spine, pancreas, breast, rectum and HN. Hypo-fractioned VMAT plans were generated using Elekta Agility MLC in Pinnacle TPS. Both …

A Team Learning Initiative In Undergraduate Medical Physics, B Loughery, J Mcbrady, M Joiner

Conference Presentation Abstracts

Purpose: To improve comprehension in traditionally difficult subjects for a senior-level undergraduate medical physics course, we designed and implemented a Team Learning technique. This work evaluates the translation of Team Learning to medical physics.  Methods: At the beginning of the term, students were sorted into 3 even teams (students/year = 14.5).  The class met twice weekly: a traditional lecture was taught first, and each team was assigned a specific 1/3 of the lecture material in which to specialize.  Each team was assigned to create a PowerPoint presentation on their material using outside references and without copying the original figures or …

A Novel Simultaneous Plan Quality And Beam Delivery Time Sparc Optimization Platform Using Primal Dual Active Set With Continuation (Pdasc), Lewei Zhao, J You, Gang Liu, X Lu, Xuanfeng Ding

Conference Presentation Abstracts

Purpose: Proton arc is a new treatment modality that delivers proton beams while continuously rotating the gantry. This study proposed a regularized l0-minimization primal dual active set with continuation (PDASC) algorithm for proton arc spot sparsity optimization to simultaneously optimize the plan quality and the beam delivery time (BDT). Methods: Based on the previously published beam delivery sequence model of IBA ProteusONE®, proton treatment delivery time is actually dominated by spot switching time (SSWT). SSWT is approximately linearly dependent on spot numbers. So we used a non-convex l0-norm to control the sparsity level of the regularized solution. The clinical objective …

Validation And Implementation Of A Dedicated Spine Stereotactic Radiosurgery Treatment Planning System, C Knill, R Sandhu, B Loughery, L Lin, Z Seymour, P Chinnaiyan, T Quinn, M Almahariq, R Deraniyagala

Conference Presentation Abstracts

Purpose: A dedicated spine stereotactic radiosurgery optimization algorithm was commissioned for 6FFF Versa HD deliveries. Plan comparisons with the existing clinical optimization algorithm along with the dosimetric validation of the deliveries were investigated. Methods: Nine stereotactic spine patients, previously treated with Pinnacle generated plans, were re-optimized using Brainlab’s SRS spine planning Element. Three additional Elements plans were created for each patient: 1) initial optimization using a pencil beam calculation algorithm (PBC), 2) Monte Carlo (MC) recalculation of the PBC plan, and 3) re-optimization of the PBC plan using Monte Carlo. Patient dose from PBC plans was compared to MC recalculated …

A Novel Technique To Evaluate Skin Toxicity In Breast Cancer Radiotherapy, R Culcasi, M Vlachaki, M Snyder

Conference Presentation Abstracts

Purpose: To evaluate skin toxicity throughout breast radiotherapy by visualizing variations in Eulerian amplified microcirculation and correlating to skin temperature as measured by a thermal camera. Methods: High-resolution monochrome video recordings and thermal images were acquired for four breast cancer patients prior to radiation treatment followed weekly over 3-5 weeks. During these visits, the radiation oncologist assessed the patient’s skin following the CTCAE scoring system. Videos were amplified by a factor of 100 for frequencies near the patient's measured heart rate (as measured by a fingertip pulse oximeter) with a bandwidth of 0.2Hz, based on a technique developed by CSAIL …

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 …