Resume

• 2013

  Master of Business Administration (M.B.A.)

  Business of Health

  The University of Texas at San Antonio

• 2005

  Spanish

  English

  Doctor of Philosophy (Ph.D.)

  Medical Physics

  University of Wisconsin-Madison

• 2003

  Master's Degree

  Medical Physics

  University of Wisconsin-Madison

• 1999

  B.S.M.E.

  Mechanical Engineering

  B.S.

  Physics

• X-ray

  Radiation

  Radiation Safety

  Medical Physics

  Medical Education

  Clinical Research

  Image Processing

  Healthcare

  MRI

  Radiation Therapy

  Image Analysis

  Physics

  Medical Devices

  Radiology

  Cancer

  Hardware Diagnostics

  Oncology

  Dosimetric Effect of Photon Beam Energy on VMAT Treatment Plan Quality Due to Body Habitus for Advanced Prostate Cancer

  The purpose of this study was to dosimetrically compare 6MV and 10MV photon beam energies in high-risk prostate cancer patients of varying body habitus using a VMAT radiation delivery technique. The objectives of the study were to evaluate if dosimetric differences exist and to investigate if differences are dependent on patient body habitus.

  Dosimetric Effect of Photon Beam Energy on VMAT Treatment Plan Quality Due to Body Habitus for Advanced Prostate Cancer

  First author publication. 1 citation as of 05/2016. Research done at Cancer Therapy and Research Center (San Antonio

  TX).

  \"Practical aspects and uncertainty analysis of biological effective dose (BED) regarding its three-dimensional calculation in multi-phase radiotherapy treatment plans\"

  Niko Papanikolaou

  Kim Seongheon

  The purpose of the study was to create detector element-specific angular correction factors for each detector of the MatriXX planar ion chamber array and compare them to vendor-default angular correction factors. Additionally

  the impact of both factors on Gamma Index was quantified using two corrections.\n\nThe correction factor of each element is determined irradiating the detector at different incidences by the ratio of the calculated expected dose to the MatriXX measured dose as a gantry angle function. To evaluate its impact

  sixty-five pre-irradiated patient-specific dose validations were re-analyzed using the gamma index with: 3%/3 mm

  2%/2 mm

  1%/1 mm criteria.\n \nThe factors for 6 MV were found to differ (7%) from the default ones for specific angles—particularly for 85°-95°. For 10 MV

  differences (1.0%) existed when correction factors were created using various size ROI´s. Two corrections were proposed

  absolute differences for 3%/3 mm

  2%/2 mm

  & 1%/1 mm were up to 1.5%

  4.2% & 4.1% (p<0.01)

  respectively.\n\nLarge differences in the default and specific factors were noted for 6 MV and lead to improvement of the absolute GI value of up to 4.2%. In general

  gamma index value increases for patient specific dose validations when using device specific factors.\n\nKey Words: Angular dependence

  2D ionization chamber array

  VMAT

  Gamma Index.\n

  Correction of the angular dependence of the Matrixx Evolution detector and its impact in the IMRT and VMAT treatment validation

  Quality assurance (QA) of the image quality for image-guided localization systems is crucial to ensure accurate visualization and localization of regions of interest within the patient. In this study

  the temporal stability of selected image parameters was assessed and evaluated for kV CBCT mode

  planar radiographic kV

  and MV modes. The motivation of the study was to better characterize the temporal variability in specific image-quality parameters. The CATPHAN

  QckV-1

  and QC-3 phantoms were used to evaluate the image-quality parameters of the imaging systems on a Varian Novalis Tx linear accelerator. The planar radiographic images were analyzed in PIPSpro with high-contrast spatial resolution (f30

  f40

  f50 lp/mm) being recorded.

  An evaluation of the stability of image-quality parameters of Varian on-board imaging (OBI) and EPID imaging systems

  Quality assurance (QA) of the image quality for image-guided localization systems is crucial to ensure accurate visualization and localization of target volumes. In this study

  a methodology was developed to assess and evaluate the constancy of the high-contrast spatial resolution

  dose

  energy

  contrast

  and geometrical accuracy of the BrainLAB ExacTrac system. An in-house fixation device was constructed to hold the QCkV-1 phantom firmly and reproducibly against the face of the flat panel detectors. Two image sets per detector were acquired using ExacTrac preset console settings over a period of three months. The image sets were analyzed in PIPSpro and the following metrics were recorded: high-contrast spatial resolution (f30

  f40

  f50 (lp/mm))

  noise

  and contrast-to-noise ratio. Geometrical image accu- racy was evaluated by assessing the length between to predetermined points of the QCkV-1 phantom. Dose and kVp were recorded using the Unfors RaySafe Xi R/F Detector. The kVp and dose were evaluated for the following: Cranial Standard (CS) (80 kV

  80 mA

  80 ms)

  Thorax Standard (TS) (120 kV

  160 mA

  160 ms)

  Abdomen Standard (AS) (120 kV

  160 mA

  130 ms)

  and Pelvis Standard (PS) (120 kV

  160 mA

  160 ms).

  Development of image quality assurance measures of the ExacTrac localization system using commercially available image evaluation software and hardware for image-guided radiotherapy

  Alonso N.

  Gutiérrez

  Florida International University - Herbert Wertheim College of Medicine

  Baptist Health South Florida

  The University of Texas Health Science Center at San Antonio

  Miami

  FL

  Asst. Vice President & Chief Physicist

  Baptist Health South Florida

  The University of Texas Health Science Center at San Antonio

  Florida International University - Herbert Wertheim College of Medicine

  Miami

  FL

  Associate Professor and Vice Chair

  Radiation Oncology