Abby Besemer, PhD

Assistant Professor & Associate Director of the Physics Residency Program


Abby Besemer, PhD

 twitterlogo.png @AbbyBesemerPhD

Residency in Medical Physics; University of Wisconsin - Madison; 2018 
PhD in Medical Physics; University of Wisconsin - Madison; 2016 
MS in Medical Physics; University of Wisconsin - Madison; 2013
BS in Physics; Indiana University - Bloomington; 2010
BS in Astronomy/Astrophysics; Indiana University - Bloomington; 2010
BS in Mathematics; Indiana University - Bloomington; 2010

American Board of Radiology - Therapeutic Radiological Physics (2019)

Professional Memberships:
American Association of Physicists in Medicine (AAPM)
American Brachytherapy Society (ABS)
Socety of Director of Academic Medical Physics Programs (SDAMPP)
American Nuclear Society (ANS)
Medical Physics for World Benefit

Clinical & Research Interests:
Patient-Specific Dosimetry for Radiopharmaceutical Therapy
Stereotactic Radiosurgery
Motion Management
Image Guided Radiation Therapy
Adaptive Radiotherapy
Safety, Quality Assurance, Standardization of Procedures
Monte Carlo

Selected Clinical and Research Projects:

Radiopharmaceutical Therapy
Radiopharmaceutical therapy is an attractive treatment option for a broad spectrum of tumor types because it has the potential to simultaneously eradicate both the primary tumor site as well as the metastatic disease throughout the body. Like external beam radiation therapy, accurate dosimetry calculations are essential for establishing dose-response relationships during radiopharmaceutical clinical trials and important for reducing the risk of normal tissue complications and optimizing tumor response during targeted radionuclide therapy. However, dosimetry calculations and treatment planning in radiopharmaceutical therapy are performed in a very different way than external beam dose calculations. Thus, the goal of my work has been to develop a Monte Carlo internal dosimetry platform and utilize it to provide patient-specific voxelized dose distributions for radiopharmaceutical pre-clinical and clinical trials. This work is in collaboration with Bryan Bednarz’s research group at the University of Wisconsin.

Fiducial Tracking on TrueBeam using kV-triggered Imaging
Intrafraction motion management is arguably one of the biggest challenges in radiation therapy. To mitigate these effects, TrueBeam offers the capability to track internally implanted fiducials using on board kV-triggered imaging during treatment. After each image is acquired, the location of fiducial is automatically detected and compared to position on the simulation CT. If any fiducial is outside a specified tolerance region then the treatment beam is paused and the patient can be realigned if needed. The main goal of this work has been to assess functionality and performance of the TrueBeam fiducial-based gating system and also compare it with the Calypso system, which is an alternative motion management device available on TrueBeams designed to track internally implanted radio-frequency beacons.

HDR Prostate Brachytherapy
Due to the ease of use and the flexibility to create highly conformal dose distributions, High Dose Rate (HDR) Brachytherapy has slowly been replacing Low Dose Rate (LDR) Brachytherapy. Here at UNMC, we have recently transitioned from LDR to HDR Brachytherapy for the treatment of prostate cancer. This procedure utilizes Oncentra Prostate which is a real-time planning software that can optimize the implant and needle geometry using ultrasound guidance while the patient is in the operating room.

One of the things that I am very passionate about is the standardization of policies and procedures. I am currently in charge of managing a departmental wiki page for internal documentation and procedures. The goal is to have a single location to store information that is easily accessible and editable by everyone in the department. Additionally, the beauty of a wiki is that it allows pages to be interlinked and is also searchable. The hope is that this will also be a great resource and educational tool for students and residents.



  1. Besemer A, Grudzinski J, Hall L and Bednarz B, 2018 “Pre-treatment 124I-CLR1404 PET accurately predicts 131I-CLR1404 dosimetry in triple negative breast cancer patient” Cancer Biotherapy and Radiopharmaceuticals.
  1. Besemer A, Yang YM, Grudzinski J, Hall L and Bednarz B, 2018 “Development and validation of RAPID: A patient-specific Monte Carlo 3D internal dosimetry platform” Cancer Biotherapy and Radiopharmaceuticals 33(4), 155-165.
  1. Labby ZE, Barraclough BA, Bayliss RA, Besemer A, Dunkerley DAP, Howard SP, 2018 “Radiation treatment planning and delivery strategies for a pregnant brain tumor patient” Journal of Applied Clinical Medical Physics 19(5), 368-374.
  1. Bednarz B., Grudzinski J., Marsh I., Besemer A., Baiu D., Weichert J., & Otto M. 2018 “Murine-specific Internal Dosimetry for Preclinical Investigations of Imaging and Therapeutic Agents” Health physics114(4), 450-45.
  1. Besemer A, Titz B, Grudzinski J, Weichert4 JP, Kuo JS, Robins HI, Hall LT, and Bednarz BP 2017 “Impact of PET and MRI threshold-based tumor volume segmentation on patient-specific targeted radionuclide therapy dosimetry using CLR1404” Med. Biol. 62.15 6008-602.  
  1. Morris ZS, Weichert JP, Saker J, Armstrong EA, Besemer A, Bednarz BP, Kimple RJ, and Harari PM 2015 "Therapeutic combination of radiolabeled CLR1404 with external beam radiation in head and neck cancer model systems" Radiotherapy and Oncology116 (3) 504-9.
  1. Besemer A, Paganetti H, and Bednarz B 2013“The clinical impact of uncertainties in the mean excitation energy of human tissues during proton therapy” Med. Biol. 58 (4) 887-902.
  1. Buchsbaum JC,Besemer A, Simmons J, Hoene T, Simoneaux V, Sandefur A, Wolanski M, Li Z, Cheng CW  2013 “Supine proton beam craniospinal radiotherapy using a novel tabletop adapter” Med Dosim 38 (1) 70–
  1. Bednarz B and Besemer A 2017 Radiation-Induced Second Cancer Risk Estimates from Radionuclide Therapy. In EPJ Web of Conferences (Vol. 153, p. 04020). EDP Sciences.
  1. Wu H, Besemer A, and Lu M 2014 "Dynamic Correlation of Synchronized Internal Tumor and External Skin Respiratory Motion for Image Guided Lung Cancer Radiation Treatment" International Journal of Computers and their Applications 21 (1) 14-23. 

Conference Publications

  1. Besemer A, “Are patient‐specific QA measurements needed for TomoTherapy 3D conformal plans?, NCC AAPM Chapter Meeting, La Crosse, Wisconsin, November 10, 2017.
  1. Adam D, A Besemer A, Marsh I, Kloepping K, Hall L, Grudzinski J, Weichert J, Otto M, “Towards Patient-Specific Treatment Planning of External Beam Radiotherapy Involving Radiosensitizers Using Nuclear Medicine Imaging”, AAPM Annual Meeting, Denver Colorado, July 30–Aug 4, 2017 [John R. Cameron Young Investigator Symposium Finalist].
  1. Marsh I, Grudzinski J, Besemer A, Weichert J, Harari P, Bednarz B, “Towards Integrated Treatment Planning of Combined External Beam Radiotherapy and Targeted “Radionuclide Therapy”, AAPM Annual Meeting, Denver Colorado, July 30–Aug 4, 2017.
  1. Besemer A, Grudzinski J, Titz B, and Bednarz B “Evaluation of dosimetric uncertainties in individualized targeted radionuclide therapy (TRT) treatment planning using pre-clinical data, AAPM Annual Meeting, Anaheim, California, July 12-16, 2015.
  1. Besemer A, Wikre P, Grudzinski J, and Bednarz B “RAPID: Radiopharmaceutical Assessment Platform for Internal Dosimetry, Society of Nuclear Medicine and Molecular Imaging (SNMMI) Meeting – MIRD Dosimetry Symposium, Baltimore, Maryland, June 3-10, 2015.
  1. Besemer A, Titz B, Grudzinski J, Kozak K, Hall L, Weichert J, and Bednarz B “Impact of PET and MRI Threshold-Based Tumor Volume Segmentation on Targeted Radionuclide Therapy Dosimetry using CLR1404, Society for Brain Mapping and Therapeutics (SBT) Meeting, Sydney, Australia, March 17-20, 2014.
  1. Shepard A, Fowler T, Besemer A, Bednarz B “A Highly Focused Small Animal Irradiator for Preclinical Trials of Low Energy Sources” American Nuclear Society (ANS) National Winter Meeting, Washington, DC, November 10-14, 2013.
  1. Besemer A, Wu H, and Lu M “Dynamic Adaptive Correlation over Synchronous Streaming Time Series”, 26th International Conference on Computer Applications in Industry and Engineering (CAINE-2013), Los Angeles, California, September 25 -27, 2013.
  1. Besemer A, Grudzinski J Titz B, P Wickre, Hall L, Weichert J, and Bednarz B “Towards Personalized Dosimetry using Diapeutic Radiopharmaceuticals”, AAPM Annual Meeting, Indianapolis, Indiana, August 4-8, 2013 [John R. Cameron Young Investigator Symposium Finalist].
  1. Besemer A, Grudzinski J Titz B, Hall L, Weichert J, and Bednarz B, “Monte Carlo-based Radiation Dosimetry for Preclinical Trials of Radiohalogenated Pharmaceuticals”, American Nuclear Society (ANS) Annual Meeting, Atlanta, Georgia, June 16-20, 2013.
  1. Besemer A, Paganetti H, Bednarz B, “Clinical impact of uncertainties in the mean excitation energy of human tissues during proton therapy”, AAPM Annual Meeting, Charlotte, North Carolina, August 1-6, 2013.
  1. Bednarz B, Besemer A, and Yang YM, “A Monte Carlo-based small animal dosimetry platform for pre-clinical trials: proof of concept”, AAPM Annual Meeting, Charlotte, North Carolina, August 1-6, 2013.
  1. Besemer A and Wu H, “Static and Dynamic Polynomial Correlations of Internal/External Marker Positions in Radiotherapy”, Ohio River Valley Chapter 2011 Spring Symposium, Cincinnati, Ohio, March 4-5, 2011.
  1. Besemer A, J Smilowitz, M Geurts, “Is Patient-Specific IMRT QA Needed for TomoTherapy 3D Conformal Radiation Therapy (3D-CRT) Treatment Plans?”, AAPM Annual Meeting, Denver Colorado, July 30–Aug 4, 2017.
  1. Jacqmin D, Labby Z, Besemer A, Schaefer K,“Dose Rate Constancy, MU Linearity and Profile Stability of the TrueBeam Radiotherapy System”, AAPM Annual Meeting, Denver Colorado, July 30–Aug 4, 2017.
  1. Jacqmin D, Huang J, Besemer A, Schaefer K, “Characterization of Spatial Drift for the AlignRT 3D Surface Imaging System Under Multiple Warm-Up Scenarios”, AAPM Annual Meeting, Denver Colorado, July 30–Aug 4, 2017.
  2. Besemer A, Hall L, Bednarz B “In-human validation of the use of pre-treatment molecular imaging for the prediction of patient-specific dosimetry in targeted radionuclide therapy (TRT)”, World Molecular Imaging Congress (WMIC), Honolulu, Hawaii Sept 2-5 2015.
  1. Besemer A and Bednarz B, “Validation of a patient-specific Monte Carlo targeted radionuclide therapy dosimetry platform”, AAPM Annual Meeting, Austin, Texas, July 20 -24, 2014.
  1. Besemer A, Titz B, Grudzinski J, Weichert J, Hall L, and Bednarz B, “Optimizing the combination of targeted radionuclide therapy agents using a multi-scale patient-specific Monte Carlo dosimetry platform”, AAPM Annual Meeting, Austin, Texas, July 20 -24, 2014.
  2. Saker J, Armstrong E, Bednarz B, Besemer A, Farhoud M, Weichert J, and Harari P, “Combination external beam and internal radiation via 131I-CLR1404 in the treatment of head and neck squamous cell carcinoma xenografts”, American Association for Cancer Research (AACR) Annual Meeting, Washington, DC, April 6-10, 2013.