Lei Ren

Journal article Med Phys · April 2013 Featured Publication PURPOSE: Setup errors and prostate intrafraction motion are main sources of localization uncertainty in prostate cancer radiation therapy. This study evaluates four different imaging modalities 3D ultrasound (US), kV planar images, cone-beam computed tomog ... Full text Link to item Cite

Commissioning and dosimetric characteristics of TrueBeam system: composite data of three TrueBeam machines.

Journal article Med Phys · November 2012 Featured Publication PURPOSE: A TrueBeam linear accelerator (TB-LINAC) is designed to deliver traditionally flattened and flattening-filter-free (FFF) beams. Although it has been widely adopted in many clinics for patient treatment, limited information is available related to ... Full text Link to item Cite

Implementation of dual-energy technique for virtual monochromatic and linearly mixed CBCTs.

Journal article Med Phys · October 2012 Featured Publication PURPOSE: To implement dual-energy imaging technique for virtual monochromatic (VM) and linearly mixed (LM) cone beam CTs (CBCTs) and to demonstrate their potential applications in metal artifact reduction and contrast enhancement in image-guided radiation ... Full text Link to item Cite

Feasibility study of a synchronized-moving-grid (SMOG) system to improve image quality in cone-beam computed tomography (CBCT).

Journal article Med Phys · August 2012 Featured Publication PURPOSE: To evaluate the feasibility of a synchronized moving grid (SMOG) system to remove scatter artifacts, improve the contrast-to-noise ratio (CNR), and reduce image lag artifacts in cone-beam CT (CBCT). METHODS: The SMOG system proposed here uses a ra ... Full text Link to item Cite

Development and clinical evaluation of a three-dimensional cone-beam computed tomography estimation method using a deformation field map.

Journal article Int J Radiat Oncol Biol Phys · April 1, 2012 Featured Publication PURPOSE: To develop a three-dimensional (3D) cone-beam computed tomography (CBCT) estimation method using a deformation field map, and to evaluate and optimize the efficiency and accuracy of the method for use in the clinical setting. METHODS AND MATERIALS ... Full text Link to item Cite

Imaging system QA of a medical accelerator, Novalis Tx, for IGRT per TG 142: Our 1 year experience

Journal article Journal of Applied Clinical Medical Physics · January 1, 2012 Featured Publication American Association of Physicists in Medicine (AAPM) task group (TG) 142 has recently published a report to update recommendations of the AAPM TG 40 report and add new recommendations concerning medical accelerators in the era of image-guided radiation th ... Full text Cite

Advances in treatment techniques: arc-based and other intensity modulated therapies.

Journal article Cancer J · 2011 Featured Publication Treatment planning and radiation delivery techniques have advanced significantly during the past 2 decades. The development of the multileaf collimator has changed the scope of radiotherapy. The dynamic conformal arc technique emerged from traditional cone ... Full text Link to item Cite

A TCP model incorporating setup uncertainty and tumor cell density variation in microscopic extension to guide treatment planning.

Journal article Med Phys · January 2011 Featured Publication PURPOSE: Tumor control probability (TCP) models have been proposed to evaluate and guide treatment planning. However, they are usually based on the dose volume histograms (DVHs) of the planning target volume (PTV) and may not properly reflect the substanti ... Full text Link to item Cite

Combining scatter reduction and correction to improve image quality in cone-beam computed tomography (CBCT).

Journal article Med Phys · November 2010 Featured Publication PURPOSE: The authors propose a combined scatter reduction and correction method to improve image quality in cone-beam computed tomography (CBCT). Although using a beam-block approach similar to previous techniques to measure the scatter, this method differ ... Full text Link to item Cite

Clinical evaluation of positioning verification using digital tomosynthesis and bony anatomy and soft tissues for prostate image-guided radiotherapy.

Journal article Int J Radiat Oncol Biol Phys · January 1, 2009 Featured Publication PURPOSE: To evaluate on-board digital tomosynthesis (DTS) for patient positioning vs. two-dimensional (2D) radiography and three-dimensional cone beam (CBCT). METHODS AND MATERIALS: A total of 92 image sessions from 9 prostate cancer patients were analyzed ... Full text Link to item Cite

A novel digital tomosynthesis (DTS) reconstruction method using a deformation field map.

Journal article Med Phys · July 2008 Featured Publication We developed a novel digital tomosynthesis (DTS) reconstruction method using a deformation field map to optimally estimate volumetric information in DTS images. The deformation field map is solved by using prior information, a deformation model, and new pr ... Full text Link to item Cite

Automatic registration between reference and on-board digital tomosynthesis images for positioning verification.

Journal article Med Phys · February 2008 Featured Publication The authors developed a hybrid multiresolution rigid-body registration technique to automatically register reference digital tomosynthesis (DTS) images with on-board DTS images to guide patient positioning in radiation therapy. This hybrid registration tec ... Full text Link to item Cite

Accelerating reconstruction of reference digital tomosynthesis using graphics hardware.

Journal article Med Phys · October 2007 Featured Publication The successful implementation of digital tomosynthesis (DTS) for on-board image guided radiation therapy (IGRT) requires fast DTS image reconstruction. Both target and reference DTS image sets are required to support an image registration application for I ... Full text Link to item Cite

Evaluation of three types of reference image data for external beam radiotherapy target localization using digital tomosynthesis (DTS).

Journal article Med Phys · August 2007 Featured Publication Digital tomosynthesis (DTS) is a fast, low-dose three-dimensional (3D) imaging approach which yields slice images with excellent in-plane resolution, though low plane-to-plane resolution. A stack of DTS slices can be reconstructed from a single limited-ang ... Full text Link to item Cite