Scholars@Duke
Lei Ren

Lei Ren

Adjunct Professor in the Department of Radiation Oncology
Radiation Oncology
lei.ren@duke.edu
Box 3295 Med Ctr, Durham, NC 27710
04209 Radiation Physics, P.O. Box 3295 DUMC, Durham, NC 27710

Scholarly Works - Conferences

3D CTGAN: generating 3D heterogeneous tissue textures for virtual phantoms

Conference Progress in Biomedical Optics and Imaging Proceedings of SPIE · January 1, 2025 Medical imaging simulation studies benefit from the use of virtual phantoms since they present a defined ground-truth to evaluate and optimize imaging devices and techniques. Currently, these phantoms are primarily morphologically focused, surface-based re ... Full text Cite

Accelerating Real-Time Imaging for Radiotherapy: Leveraging Multi-GPU Training with PyTorch

Conference Proceedings 22nd IEEE International Conference on Machine Learning and Applications Icmla 2023 · January 1, 2023 Proton beam therapy is an advanced form of cancer radiotherapy that uses high-energy proton beams to deliver precise and targeted radiation to tumors. This helps to mit-igate unnecessary radiation exposure in healthy tissues. Real-time imaging of prompt ga ... Full text Cite

Liver synthetic CT generation based on dense-cyclegan for MRI-only treatment planning

Conference Progress in Biomedical Optics and Imaging Proceedings of SPIE · January 1, 2020 The application of MRI significantly improves the accuracy and reliability of target delineation for many disease sites in radiotherapy due to its superior soft tissue contrast as compared to CT. However, MRI data do not contain the electron density inform ... Full text Cite

Quantifying Imaging Radiation to Patient from Optimized Procedures with LIVE System during SBRT Lung Treatment

Conference International Journal of Radiation Oncology*Biology*Physics · September 2019 Full text Cite

Ultrafast Volumetric Cine Magnetic Resonance Imaging (UVC-MRI) for Real-Time 3-Dimensional Target Localization/Tracking

Conference INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS · October 1, 2016 Link to item Cite

SU-D-204-01: A Methodology Based On Machine Learning and Quantum Clustering to Predict Lung SBRT Dosimetric Endpoints From Patient Specific Anatomic Features.

Conference Med Phys · June 2016 PURPOSE: To develop a data-mining methodology based on quantum clustering and machine learning to predict expected dosimetric endpoints for lung SBRT applications based on patient-specific anatomic features. METHODS: Ninety-three patients who received lung ... Full text Link to item Cite

TH-EF-BRA-02: A Novel Markerless 4D CBCT Projection Phase Sorting Technique Using Prior Knowledge and Patient Motion Modeling: A Feasibility Study.

Conference Med Phys · June 2016 PURPOSE: To investigate the feasibility of a novel marker-less motion-modeling based method for automatic 4D-CBCT projection phase sorting. METHODS: Patient on-board image volume at any instant is considered as a deformation of one phase of the prior plann ... Full text Link to item Cite

TH-EF-BRA-08: A Novel Technique for Estimating Volumetric Cine MRI (VC-MRI) From Multi-Slice Sparsely Sampled Cine Images Using Motion Modeling and Free Form Deformation.

Conference Med Phys · June 2016 PURPOSE: To develop a technique to estimate on-board VC-MRI using multi-slice sparsely-sampled cine images, patient prior 4D-MRI, motion-modeling and free-form deformation for real-time 3D target verification of lung radiotherapy. METHODS: A previous metho ... Full text Link to item Cite

SU-G-JeP3-01: A Method to Quantify Lung SBRT Target Localization Accuracy Based On Digitally Reconstructed Fluoroscopy.

Conference Med Phys · June 2016 PURPOSE: To develop a methodology based on digitally-reconstructed-fluoroscopy (DRF) to quantitatively assess target localization accuracy of lung SBRT, and to evaluate using both a dynamic digital phantom and a patient dataset. METHODS: For each treatment ... Full text Link to item Cite

TU-AB-BRA-09: A Novel Method of Generating Ultrafast Volumetric Cine MRI (VC-MRI) Using Prior 4D-MRI and On-Board Phase-Skipped Encoding Acquisition for Radiotherapy Target Localization.

Conference Med Phys · June 2016 PURPOSE: To develop a technique generating ultrafast on-board VC-MRI using prior 4D-MRI and on-board phase-skipped encoding k-space acquisition for real-time 3D target tracking of liver and lung radiotherapy. METHODS: The end-of-expiration (EOE) volume in ... Full text Link to item Cite

WE-DE-BRA-01: SCIENCE COUNCIL JUNIOR INVESTIGATOR COMPETITION WINNER: Acceleration of a Limited-Angle Intrafraction Verification (LIVE) System Using Adaptive Prior Knowledge Based Image Estimation.

Conference Med Phys · June 2016 PURPOSE: To develop an adaptive prior knowledge based image estimation method to reduce the scan angle needed in the LIVE system to reconstruct 4D-CBCT for intrafraction verification. METHODS: The LIVE system has been previously proposed to reconstructs 4D ... Full text Link to item Cite

SU-G-JeP4-02: An Investigation of Respiratory Surrogate Motion Data Requirements for Multiple-Step Ahead Prediction.

Conference Med Phys · June 2016 PURPOSE: Respiratory-gated radiotherapy and dynamic tracking employ real-time imaging and surrogate motion-monitoring methods with tumor motion prediction in advance of real-time. This study investigated respiratory motion data length on prediction accurac ... Full text Link to item Cite

SU-G-JeP3-06: Lower KV Image Dose Are Expected From a Limited-Angle Intra-Fractional Verification (LIVE) System for SBRT Treatments.

Conference Med Phys · June 2016 PURPOSE: In order to track the tumor movement for patient positioning verification during arc treatment delivery or in between 3D/IMRT beams for stereotactic body radiation therapy (SBRT), the limited-angle kV projections acquisition simultaneously during ... Full text Link to item Cite

SU-G-JeP3-04: Estimating 4D CBCT from Prior Information and Extremely Limited Angle Projections Using Structural PCA and Weighted Free-Form Deformation.

Conference Med Phys · June 2016 PURPOSE: To investigate the feasibility of using structure-based principal component analysis (PCA) motion-modeling and weighted free-form deformation to estimate on-board 4D-CBCT using prior information and extremely limited angle projections for potentia ... Full text Link to item Cite

TH-C-BRC-03: Emerging Linac Based SRS/SBRT Technologies with Modulated Arc Delivery.

Conference Med Phys · June 2016 The delivery techniques for SRS/SBRT have been under rapid developments in recent years, which pose new challenges to medical physicists ranging from planning and quality assurance to imaging and motion management. This educational course will provide a ge ... Full text Link to item Cite

SU-F-J-82: A Rapid Direct Method for Inverting Respiratory Deformation Fields.

Conference Med Phys · June 2016 PURPOSE: To enable efficient and consistent registrationbetween source and target images, related bynonlinear but periodic deformation, with particular focus on 4D CTimages. METHODS: We present a non-iterative method for inverting forward (or backward) def ... Full text Link to item Cite

TH-C-BRC-00: Emerging Technologies in SRS/SBRT Delivery.

Conference Med Phys · June 2016 The delivery techniques for SRS/SBRT have been under rapid developments in recent years, which pose new challenges to medical physicists ranging from planning and quality assurance to imaging and motion management. This educational course will provide a ge ... Full text Link to item Cite

SU-F-I-10: Spatially Local Statistics for Adaptive Image Filtering.

Conference Med Phys · June 2016 PURPOSE: To facilitate adaptive image filtering operations, addressing spatial variations in both noise and signal. Such issues are prevalent in cone-beam projections, where physical effects such as X-ray scattering result in spatially variant noise, viola ... Full text Link to item Cite

SU-F-J-83: Estimation of Deformation Field with Two-Scale Supervoxel Equations.

Conference Med Phys · June 2016 PURPOSE: To circumvent the ill-posedness in the problem to estimate inhomogeneous motion or deformation field without resorting to global regularization conditions. METHODS: We present a novel method for deformable registration. First, we estimate the defo ... Full text Link to item Cite

SU-F-J-138: An Extension of PCA-Based Respiratory Deformation Modeling Via Multi-Linear Decomposition.

Conference Med Phys · June 2016 PURPOSE: To address and lift the limited degree of freedom (DoF) of globally bilinear motion components such as those based on principal components analysis (PCA), for encoding and modeling volumetric deformation motion. METHODS: We provide a systematic ap ... Full text Link to item Cite

Phase-matched DTS Imaging for Lung Tumor Localization

Conference International Journal of Radiation Oncology*Biology*Physics · November 2015 Full text Cite

WE-G-BRD-06: Volumetric Cine MRI (VC-MRI) Estimated Based On Prior Knowledge for On-Board Target Localization.

Conference Med Phys · June 2015 PURPOSE: To develop a technique to generate on-board VC-MRI using patient prior 4D-MRI, motion modeling and on-board 2D-cine MRI for real-time 3D target verification of liver and lung radiotherapy. METHODS: The end-expiration phase images of a 4D-MRI acqui ... Full text Link to item Cite

SU-E-T-341: DVH-Based Comparison of True 3D Measurements to a Delta4 System.

Conference Med Phys · June 2015 PURPOSE: Delta4 dosimetric software can be used to calculate DVH-based metrics for patient-specific quality assurance from measurements made by a Delta4 QA device. This study investigates the effectiveness of a novel transform method that transposes measur ... Full text Link to item Cite

TH-D-BRD-01: X-Ray Based Real Time Imaging Verification.

Conference Med Phys · June 2015 UNLABELLED: Radiotherapy of moving targets, such as lung, liver or prostate tumors, is prone to treatment errors due to the uncertainties in the target position. Minimizing such error is critical for radiotherapy treatments, especially hypofractionated SBR ... Full text Link to item Cite

TH-CD-303-06: Deformable Registration-Based Image Estimation Method for 4D CBCT Using Region-Based PCA.

Conference Med Phys · June 2015 PURPOSE: To investigate the feasibility of using region-based principal component analysis (PCA) for motion modeling to estimate on-board 4D-CBCT using prior information and limited angle projections for potential 4D target verification of lung radiotherap ... Full text Link to item Cite

TH-AB-303-02: An Investigation of Respiratory Signal Parameters for Multiple-Step Ahead Prediction of Surrogate Motion.

Conference Med Phys · June 2015 PURPOSE: Target tracking or gating the radiation beam using real-time imaging and surrogate motion monitoring methods are employed for dynamic tracking treatment or respiratory-gated radiotherapy. This method requires tumor motion prediction far enough in ... Full text Link to item Cite

WE-EF-207-04: An Inter-Projection Sensor Fusion (IPSF) Approach to Estimate Missing Projection Signal in Synchronized Moving Grid (SMOG) System.

Conference Med Phys · June 2015 PURPOSE: A synchronized moving grid (SMOG) has been proposed to reduce scatter and lag artifacts in cone beam computed tomography (CBCT). However, information is missing in each projection because certain areas are blocked by the grid. A previous solution ... Full text Link to item Cite

WE-EF-207-08: Improve Cone Beam CT Using a Synchronized Moving Grid, An Inter-Projection Sensor Fusion and a Probability Total Variation Reconstruction.

Conference Med Phys · June 2015 PURPOSE: To present a cone beam computed tomography (CBCT) system, which uses a synchronized moving grid (SMOG) to reduce and correct scatter, an inter-projection sensor fusion (IPSF) algorithm to estimate the missing information blocked by the grid, and a ... Full text Link to item Cite

WE-D-303-05: Dosimetric Accuracy of CBCT Images Estimated by a Motion Modeling and Free-Form Deformation Technique for Radiotherapy of Lung Cancer.

Conference Med Phys · June 2015 PURPOSE: To investigate the dosimetric accuracy of CBCTs estimated by a motion modeling and free-form deformation(MM-FD) technique for radiotherapy of lung cancer. METHODS: Various inter-fractional variations featuring patient motion pattern change, tumor ... Full text Link to item Cite

WE-D-303-06: Multi-Layer Spectral Analysis for Tensor Structure Encoding of 4D Deformation Field Data.

Conference Med Phys · June 2015 PURPOSE: Adaptive denoising and encoding of 4D deformation-vector-field (DVF) extracted from 4D planning CT, for modeling patient dominant motion features across coupled trajectory dimensions and respiratory phases. METHODS: We propose a multi-layer spectr ... Full text Link to item Cite

WE-AB-303-01: FEATURED PRESENTATION: A Dual-Detector Phase-Matched Digital Tomosynthesis (DTS) Imaging Scheme Using Aggregated KV and MV Projections for Intra-Treatment Lung Tumor Tracking.

Conference Med Phys · June 2015 PURPOSE: To develop a dual-detector phase-matched DTS technique for continuous and fast intra-treatment lung tumor localization. METHODS: Tumor localization accuracy of limited-angle DTS imaging is affected by low inter-slice resolution. The dual-detector ... Full text Link to item Cite

WE-AB-303-09: Rapid Projection Computations for On-Board Digital Tomosynthesis in Radiation Therapy.

Conference Med Phys · June 2015 PURPOSE: To facilitate fast and accurate iterative volumetric image reconstruction from limited-angle on-board projections. METHODS: Intrafraction motion hinders the clinical applicability of modern radiotherapy techniques, such as lung stereotactic body r ... Full text Link to item Cite

SU-E-T-293: Dosimetric Analysis of Microscopic Disease in SBRT for Lung Cancers.

Conference Med Phys · June 2015 PURPOSE: To evaluate the dosimetry of microscopic disease (MD) region of lung cancer in stereotactic body radiation therapy (SBRT). METHODS: For simplicity, we assume organ moves along one dimension. The probability distribution function of tumor position ... Full text Link to item Cite

SU-E-J-26: A Novel Technique for Markerless Self-Sorted 4D-CBCT Using Patient Motion Modeling: A Feasibility Study.

Conference Med Phys · June 2015 PURPOSE: To develop an automatic markerless 4D-CBCT projection sorting technique by using a patient respiratory motion model extracted from the planning 4D-CT images. METHODS: Each phase of onboard 4D-CBCT is considered as a deformation of one phase of the ... Full text Link to item Cite

SU-E-I-40: Phantom Research On Monochromatic Images Taken by Dual CBCT with Multiple Energy Sets.

Conference Med Phys · June 2015 PURPOSE: To evaluate the quality of monochromatic images at the same virtual monochromatic energy using dual cone-beam computed tomography (CBCT) with either kV/kV or MV/kV or MV/MV energy sets. METHODS: CT images of Catphan 504 phantom were acquired using ... Full text Link to item Cite

An Inter-Projection Interpolation (IPI) Approach with Geometric Model Restriction to Reduce Image Dose in Cone Beam CT (CBCT).

Conference Comput Model Objects Present Images (2014) · September 2014 Cone beam computed tomography (CBCT) imaging is a key step in image guided radiation therapy (IGRT) to improve tumor targeting. The quality and imaging dose of CBCT are two important factors. However, X-ray scatter in the large cone beam field usually indu ... Full text Link to item Cite

Dosimetric Evaluation of a Limited-angle Intrafraction Verification (LIVE) System

Conference International Journal of Radiation Oncology*Biology*Physics · September 2014 Full text Cite

Lung 4D-CBCT Reconstruction Using Prior Information and Limited-Angle Projections: Phantom and Patient Studies

Conference International Journal of Radiation Oncology*Biology*Physics · September 2014 Full text Cite

TH-A-18C-05: Scatter Reduction and Correction for Dual-Source CBCT Using the Synchronized Moving Grid (SMOG) System.

Conference Med Phys · June 2014 PURPOSE: to implement the newly developed synchronized moving grid (SMOG) system on a prototype dual-source CBCT system to evaluate its efficacy for scatter reduction and correction under various settings, including different phantom size, grid ratio and i ... Full text Link to item Cite

SU-E-T-472: A Multi-Dimensional Measurements Comparison to Analyze a 3D Patient Specific QA Tool.

Conference Med Phys · June 2014 PURPOSE: To quantitatively evaluate a 3D patient specific QA tool using 2D film and 3D Presage dosimetry. METHODS: A brain IMRT case was delivered to Delta4, EBT2 film and Presage plastic dosimeter. The film was inserted in the solid water slabs at 7.5cm d ... Full text Link to item Cite

SU-E-I-56: Scan Angle Reduction for a Limited-Angle Intrafraction Verification (LIVE) System.

Conference Med Phys · June 2014 PURPOSE: To develop a novel adaptive reconstruction strategy to further reduce the scanning angle required by the limited-angle intrafraction verification (LIVE) system for intrafraction verification. METHODS: LIVE acquires limited angle MV projections fro ... Full text Link to item Cite

WE-G-BRF-03: A Quasi-Cine CBCT Reconstruction Technique for Real-Time On- Board Target Tracking of Lung Cancer Treatment.

Conference Med Phys · June 2014 PURPOSE: To develop a quasi-cine CBCT reconstruction technique that uses extremely-small angle (∼3°) projections to generate real-time high-quality lung CBCT images. METHOD: 4D-CBCT is obtained at the beginning and used as prior images. This study uses ext ... Full text Link to item Cite

SU-E-I-08: An Inpaint-Based Interpolation Technique to Recover Blocked Information for Cone Beam CT with a Synchronized Moving Grid (SMOG).

Conference Med Phys · June 2014 PURPOSE: Synchronized moving grid (SMOG) is a promising technique to reduce scatter and ghost artifacts in cone beam computed tomography (CBCT). However, the grid blocks part of image information in each projection, and multiple projections at the same gan ... Full text Link to item Cite

SU-D-17A-01: Geometric and Dosimetric Evaluation of a 4D-CBCT Reconstruction Technique Using Prior Knowledge.

Conference Med Phys · June 2014 PURPOSE: To evaluate a 4D-CBCT reconstruction technique both geometrically and dosimetrically METHODS: A prior-knowledge guided 4DC-BCT reconstruction method named the motion-modeling and free-form deformation (MM-FD) has been developed. MM-FD views each p ... Full text Link to item Cite

SU-D-18A-02: Towards Real-Time On-Board Volumetric Image Reconstruction for Intrafraction Target Verification in Radiation Therapy.

Conference Med Phys · June 2014 PURPOSE: To expedite on-board volumetric image reconstruction from limited-angle kV-MV projections for intrafraction verification. METHODS: A limited-angle intrafraction verification (LIVE) system has recently been developed for real-time volumetric verifi ... Full text Link to item Cite

SU-D-12A-01: An Inter-Projection Interpolation (IPI) Approach for the Synchronized Moving Grid (SMOG) to Reduce Dose in Cone Beam CT.

Conference Med Phys · June 2014 PURPOSE: Synchronized moving grid is a promising technique to reduce scatter and ghost artifacts in cone beam computed tomography (CBCT). However, it requires 2 projections in the same gantry angle to obtain full information due to signal blockage by the g ... Full text Link to item Cite

SU-E-J-246: A Deformation-Field Map Based Liver 4D CBCT Reconstruction Method Using Gold Nanoparticles as Constraints.

Conference Med Phys · June 2014 PURPOSE: To investigate the feasibility of using nanoparticle markers to validate liver tumor motion together with a deformation field map-based four dimensional (4D) cone-beam computed tomography (CBCT) reconstruction method. METHODS: A technique for lung ... Full text Link to item Cite

SU-E-T-159: Evaluation of a Patient Specific QA Tool Based On TG119.

Conference Med Phys · June 2014 PURPOSE: To evaluate the accuracy of a 3D patient specific QA tool by analysis of the results produced from associated software in homogenous phantom and heterogonous patient CT. METHODS: IMRT and VMAT plans of five test suites introduced by TG119 were cre ... Full text Link to item Cite

A Simulation Study of Treatment Verification Using On-Board Multipinhole SPECT

Conference International Journal of Radiation Oncology*Biology*Physics · October 2013 Full text Cite

SU-E-T-196: Pretreatment Patient Clinical Objective IMRT Quality Assurance Using a 3D Diode Array.

Conference Med Phys · June 2013 PURPOSE: To evaluate the accuracy and sensitivity of a patient clinical objective IMRT QA tool using a 3D diode array. METHODS: A 3D QA device (Delta4, Scandidos Inc.) with 2 orthogonal diode array planes was used for IMRT QA. The diode spacing is 5mm in c ... Full text Link to item Cite

WE-G-141-07: Feasibility of Using a Grid to Detect and Correct the Geometric Variations in Flat-Panel Based Cone Beam CT.

Conference Med Phys · June 2013 PURPOSE: To study the feasibility of using a grid, shown previously to mitigate the scatter problem, to detect and correct geometric variations in flat-panel-based cone beam CT (CBCT) imaging. METHODS: The study was performed on the CBCT system of a Varian ... Full text Link to item Cite

MO-F-WAB-11: Investigation of CBCT-Based Patient Positioning Accuracy in Lung SBRT: Correlation with Breathing Irregularity.

Conference Med Phys · June 2013 PURPOSE: To evaluate breathing irregularity induced error in CBCT-based patient positioning in lung SBRT and correlate the error with a measure of breathing variability. METHODS: The 4D extended cardiac-torso (XCAT) digital phantom was used to generate 10- ... Full text Link to item Cite

SU-E-T-560: A Method to Determine Optimal Dynamic MLC Parameters for Varian Truebeam with Millennium MLC and HDMLC.

Conference Med Phys · June 2013 PURPOSE: Correct MLC modeling is essential to the accurate IMRT delivery. Most TPSs use simplified models with parameters of leaf transmission (LT) and dynamic leaf gap (DLG). The common way to determine them is through extrapolation from measurements. In ... Full text Link to item Cite

WE-A-134-04: Comprehensive Evaluation of a Respiration-Phase-Matched Digital Tomosynthesis (DTS) Imaging Technique for Monitoring Moving Targets.

Conference Med Phys · June 2013 PURPOSE: To develop a respiration-phase-matched DTS technique to monitor moving targets, and to evaluate its accuracy for various imaging parameters and anatomical characteristics Methods: Conventional methods, registering on-board DTS(OB-DTS, reconstructe ... Full text Link to item Cite

TU-G-141-03: An On-Board 4D-CBCT Reconstruction Technique Using Limited-Angle Projections Based On Motion Modeling and Free-Form Deformation (MM-FD).

Conference Med Phys · June 2013 PURPOSE: To develop an on-board 4D-CBCT(OB-4D-CBCT) reconstruction technique using prior information and limited-angle projections for 4D inter/intra-fractional target verificationMethods: The OB-4D-CBCT at each phase is considered as a deformation of plan ... Full text Link to item Cite

Can Standard Radiation Therapy Quality Assurance (QA) Detect Potential Delivery Errors?

Conference International Journal of Radiation Oncology*Biology*Physics · November 2012 Full text Cite

SU-E-T-645: Treatment of Multiple Brain Metastases Using Stereotactic Radiosurgery with Single-Isocenter Volumetric Modulated Arc Therapy: Comparison with Conventional Dynamic Conformal Arc and Static Beam Stereotactic Radiosurgery.

Conference Med Phys · June 2012 PURPOSE: To investigate the treatment of multiple brain metastases using stereotactic radiosurgery with single-isocenter volumetric modulated arc therapy (VMAT) compared with conventional multi-isocenter dynamic conformal arc therapy (DCAT) and three-dimen ... Full text Link to item Cite

Dosimetric Evaluation and Optimization of a Novel CBCT Estimation Method for Adaptive Radiation Therapy (ART)

Conference International Journal of Radiation Oncology*Biology*Physics · October 2011 Full text Cite

MO‐D‐BRC‐01: Dosimetric Evaluation of a Novel Cone‐Beam CT (CBCT) Estimation Method Using Prior Information for Lung Cancer Patient Treatment

Conference Medical Physics · January 1, 2011 Purpose: To evaluate the dosimetric accuracy of a novel CBCT estimation method using prior information for use in adaptive radiotherapy (ART)‐based treatment of lung cancer patients. Methods: Patient planning CT or previous day's CBCT images are used as th ... Full text Cite

SU‐E‐J‐21: Verification of a Monte Carlo Model of CBCT Flat Panel Detector Using BEAMnrc/EGSnrc Code

Conference Medical Physics · January 1, 2011 Purpose: Cone beam computed tomography (CBCT) provides wide scan coverage per rotation; however, its image quality is compromised due to large amounts of scatter. In this study, we performed detailed Monte Carlo (MC) simulations of a CBCT flat panel detect ... Full text Cite

MO‐D‐BRC‐06: A Multi‐Exposure Approach to Improve Image Quality for Linac‐Based Cone Beam Computed Tomography (CBCT)

Conference Medical Physics · January 1, 2011 Purpose: Recently we demonstrated the use of a 1‐D grid placed between the source and patient to directly reduce scatter, and correct the remaining scatter in cone‐beam computed tomography (CBCT). However, that technique required two 360° gantry rotations ... Full text Cite

TH‐E‐BRC‐11: Practical Methods for Improving Dose Non‐Uniformity in Monte Carlo‐ Based IMRT Planning of Lung Tumors Treated with Stereotactic Body Radiotherapy (SBRT)

Conference Medical Physics · January 1, 2011 Purpose: Current commercially available planning systems which utilize MC algorithm‐based final dose calculation in IMRT planning employ pencil‐beam algorithms in the optimization process. Consequently, dose coverage for SBRT lung plans can be quite non‐un ... Full text Cite

SU‐DD‐A4‐03: Cone Beam Computed Tomography Reconstruction on Graphics Processing Units: Flat3D Texture Techniques

Conference Medical Physics · January 1, 2010 Purpose: Graphics processing units (GPUs) can shorten cone‐beam volume reconstruction time significantly in comparison to CPUs. We evaluated Flat3D texture techniques to further enhance calculation efficiency. Methods: Typical reconstruction involves proce ... Full text Cite

TU‐C‐204B‐01: Reduce Patient Dose and Improve Image Quality in CBCT for Image Guided Radiotherapy

Conference Medical Physics · January 1, 2010 Introduction: We have demonstrated that cone beam CT (CBCT) image quality was substantially improved in terms of eliminating scatter related artifacts and enhancing contrast‐to‐noise ratio, using a 1D grid placed between the x‐ray source and the imaging ob ... Full text Cite

TU‐C‐204B‐07: A Comparative Study for Daily Localization with 3D Ultrasound, Cone Beam CT, Implanted Prostate Fiducial Markers and Calypso 4D Localization System for Patients Undergoing IGRT for Prostate Cancer

Conference Medical Physics · January 1, 2010 Purpose: To assess the accuracy and dosimetric implications of multi‐modality, online image‐guided localization methods, including intra‐modality 3D prostate ultrasound, cone beam CT (CBCT), implanted prostate markers and Calypso 4D localization for patien ... Full text Cite

SU‐GG‐J‐30: A Novel Scatter Reduction and Correction Method to Improve Cone‐Beam CT (CBCT) Image Quality

Conference Medical Physics · January 1, 2010 Purpose: To develop a novel scatter reduction and correction method to improve the CBCT image quality for IGRT applications. Method and Materials: A one‐dimensional grid composed of lead with equal interspacing was positioned between the x‐ray source and t ... Full text Cite

MO‐E‐BRA‐05: Clinical Issues Associated with the Use of Monte Carlo‐Based Prospective Planning for Lung SBRT and Spine SRS Patients

Conference Medical Physics · January 1, 2010 Purpose: To investigate the clinical issues associated with the use of Monte Carlo‐based prospective planning for lung SBRT and spine SRS patients. Methods: Experimental verification of the iPlan v.4.1 MC photon beam algorithm (BrainLab) was performed usin ... Full text Cite

SU‐FF‐J‐09: Limited‐Angle Imaging for Target Positioning Using Orthogonal Conebeam X‐Ray Systems

Conference Medical Physics · January 1, 2009 Purpose: To investigate limited‐angle imaging using orthogonal x‐ray systems, with regard to use for target positioning onboard external beam radiation therapy (EBRT) machines. Method and Materials: Image reconstruction was performed using projection data ... Full text Cite

TH‐A‐211A‐01: Digital Tomosynthesis for Target Localization

Conference Medical Physics · January 1, 2009 Any deviation between treated and planned volumes for 3‐D conformal therapy, such as IMRT, may cause an adverse clinical outcome. It is therefore critical to minimize all potential deviations using an on‐board (or real‐time) imaging procedure immediately p ... Full text Cite

Limited-angle DTS Imaging using CT Bone Information

Conference International Journal of Radiation Oncology*Biology*Physics · September 2008 Full text Cite

A Novel Digital Tomosynthesis (DTS) Reconstruction Method using Prior Information and a Deformation Model

Conference International Journal of Radiation Oncology*Biology*Physics · September 2008 Full text Cite

SU‐GG‐I‐52: Conversion of On‐Board Digital TomoSynthesis (DTS) to HU Values

Conference Medical Physics · January 1, 2008 Purpose: To investigate a method to convert the pixel values of DTS images to HU values with reference HU values from CT images. Method and Materials: This study included CT and DTS images of two phantoms (Catphan and a chest phantom) and three patients (p ... Full text Cite

SU‐GG‐J‐119: Localization Accuracy of Target Verification System Using Digitial Tomosynthesis (DTS)

Conference Medical Physics · January 1, 2008 Purposes: A research platform was developed for target verification using digital tomosynthesis (DTS). To verify its accuracy, a phantom study was conducted and several clinical cases were investigated. Method and Materials: customer‐developed reconstructi ... Full text Cite

SU‐GG‐I‐53: The Impact of Scan Angles On the Visibility of Anatomy in On‐Board Digital Tomosynthesis (DTS) Images for Head and Neck Cancer Patients: A Single‐Observer Study

Conference Medical Physics · January 1, 2008 Purpose: To assess the impact of scan angles on the visibility of anatomy in on‐board digital tomosynthesis (DTS) images as a means to optimize this technique. Method and Materials: Head and neck cancer patients undergoing intensity‐modulated radiotherapy ... Full text Cite

TH‐D‐351‐02: A Novel Digital Tomosynthesis (DTS) Reconstruction Method Using Prior Information and a Deformation Model

Conference Medical Physics · January 1, 2008 Purpose: Digital Tomosynthesis (DTS) is a quasi‐3D imaging technique which reconstructs images from a limited angle of on‐board projections with significantly lower dose and shorter acquisition time than full cone‐beam CT (CBCT). However, DTS images recons ... Full text Cite

SU‐GG‐I‐47: A New Limited‐Angle CT Reconstruction Method Based On Total‐Variation Minimization

Conference Medical Physics · January 1, 2008 Purpose: To develop a new CT reconstruction algorithm based on Total‐Variation (TV) minimization. The new algorithm is specifically designed for limited angle reconstruction to alleviate volume information loss caused by incomplete projections. Method and ... Full text Cite

Implementation of Digital Tomosynthesis for On-Board Target Localization of Radiotherapy

Conference International Journal of Radiation Oncology*Biology*Physics · November 2007 Full text Cite

SU‐FF‐J‐54: A Hybrid Multiresolution Method for Automatic Registration Between Reference and On Board Digital Tomosynthesis

Conference Medical Physics · January 1, 2007 Purpose: Automatic registration between reference and on‐board digital tomosynthesis (DTS) is a critical step for target localization using DTS. We previously developed an approximate method for automatic registration between reference and on‐board DTS, in ... Full text Cite

SU‐FF‐I‐39: Development of Clinical Application Platform Using Digital Tomosynthesis for Target Localization

Conference Medical Physics · January 1, 2007 Purpose: To develop a workstation for clinical application of digital tomosynthesis (DTS) for real‐time target localization. Specifically, to accelerate the reconstruction both digitally‐reconstructed radiograph (DRR) and DTS using ultra‐fast interpolation ... Full text Cite

TH‐C‐ValB‐04: Evaluation of the Quality of 3D‐3D Mutual Information (MI) Shared Between Reference and On‐Board DTS Images

Conference Medical Physics · January 1, 2006 Purpose: Digital tomosynthesis (DTS) is a fast, low‐dose method for reconstructing 3‐D slices from 2‐D cone‐beam x‐ray projection data acquired with limited source angulation (e.g., 40°). We previously developed a method for reconstructing reference DTS (R ... Full text Cite

SU‐CC‐ValA‐01: Automatic Comparison Between Reference and On Board Digital Tomosynthesis for Target Localization

Conference Medical Physics · January 1, 2006 Purpose: Digital tomosynthesis (DTS) is a method for reconstructing 3D images from cone‐beam projection data acquired with limited angulation (e.g., 40°) of an x‐ray source, and is much faster and lower dose than full cone‐beam CT (CBCT). We previously dev ... Full text Cite