Latest Publications from RED²: FLASH Radiotherapy and Machine Learning Reference for Computational Phantom Dosimetry

As part of two key research thrusts in the RED² Laboratory – check out our latest publications in radiation shielding and in computational dosimetry!

Our first publication is led by Ph.D. candidate, Andrew Rosenstrom, in a study entitled, “Monte Carlo simulation of shielding designs for a cabinet form factor preclinical MV-energy photon FLASH radiotherapy system“, published in the journal, Medical Physics. This study investigates the use of alternating multilayered shielding compared to monolayered designs to mitigate secondary radiation for FLASH radiotherapy applications.  Learn more about Andrew’s work at Stanford Linear Accelerator Laboratory and the impacts of his work in new modalities in FLASH radiotherapy.


A second publication was a study conducted by RED² Laboratory collaborators, Dr. Keith Griffin (left, recent Georgia Tech NRE/MP Ph.D. graduate and Post-Doctoral Fellow at NIH/NCI) and Mr. David Coleman (right, University of Wisconsin Medical Physics Ph.D. student and former RED² Laboratory undergraduate researcher) entitled, “Stylized versus voxel phantoms: quantification of internal organ chord length distances” in the journal, Physics in Medicine and Biology. This study is a follow-on to a prior effort investigating the organ distribution between stylized and voxel phantoms to determine the inter and intra-organ placement for future use in individualized phantom dosimetry, applications limiting the need for traditional Monte Carlo in the computation of individualized SAFs, and for future use in machine learning. Included this study is a very extensive electronic supplementary data appendix with full results to share with the research community. The paper and supporting data are available via OpenAccess.

RED²’s Rosenstrom wins Lutz Moritz Memorial Award

Congratulations to RED² Ph.D. candidate, Andrew Rosenstrom, for being selected as the awardee for the Lutz Moritz Memorial Award by the Accelerator Section at the 67th Annual Meeting of the Health Physics Society in Spokane, WA (July 16-21,2022)  for his work on “High Power Beam Dump Shielding Design for the LCLS-II-HE Low Emittance Injector”.

Rosenstrom presenting at the 67th Annual Meeting of the Health Physics Society (July 19, 2022).

Established in 2009, the Lutz Moritz Memorial Award is presented yearly at the annual Health Physics Society meeting to recognize outstanding student presentations on accelerator health physics.  The award is a tribute to Lutz Moritz (1943-2008), who was a founding member of the Accelerator Section and served as president of the section in 1996. Lutz’s distinguished career at TRIUMF, Canada’s National Laboratory for Particle and Nuclear Physics, earned him an international reputation as Canada’s foremost expert on accelerator radiation safety.

Congratulations also to former RED² undergraduate researcher (now Texas A&M University graduate student), Jordan Hillis, for being awarded the 2022 H. Wade Patterson Memorial Award at the HPS Meeting in Spokane, Washington, in recognition of her presentation, “Analysis of Relative Hazards and Detection Capabilities for Radionuclides at the Spallation Neutron Source”.

Visit the Accelerator Section of the Health Physics Society here and thank you to the AS for supporting our next generation leaders!

U.S. Needs New $100 Million Research Program to Study Health Effects of Exposure to Low Doses of Radiation, Says New Report

The report estimates $100 million annually for the next 15 years would be required to conduct epidemiological and biological research, and to establish an infrastructure for research. Reproduced from:

Dr. Shaheen Dewji from the George W. Woodruff School of Mechanical Engineering – Nuclear and Radiological Engineering and Medical Physics Programs at Georgia Institute of Technology was a contributing author and member of the Committee on Developing a Long-Term Strategy for Low-Dose Radiation Research in the United States to the cited study.


NOTE: Reproduced from original article  available on NASEM website:


News Release | June 2, 2022


WASHINGTON — The U.S. should establish a new coordinated research program to investigate the impacts of exposure to low doses of radiation on human health, says a new report from the National Academies of Sciences, Engineering, and Medicine. The report estimates $100 million annually for the next 15 years would be required to conduct epidemiological and biological research, and to establish an infrastructure for research. This coordinated program should study how low doses of radiation affect cancer risks, cardiovascular disease risk, neurological disorders, and other disease — and try to establish causal links to health conditions. Research should also better define the impacts of radiation doses, dose rates, types of radiation, and exposure duration.

Radiation exposure at low doses (below 100 milligray) or low-dose rates (less than 5 milligray per hour) occurs in a wide range of medical, industrial, military, and commercial settings. The effects of exposure at these levels are not fully understood, the report says, and there are long-standing concerns that such exposure could negatively affect human health. Although cancer has been linked to low-dose radiation exposure for decades, there is increasing evidence that it may also be associated with cardiovascular disease, neurological disorders, immune dysfunction, and cataracts.

Concerns about the health effects of low doses of radiation raise questions as to whether the public and workers are adequately protected from exposures from medical diagnostics procedures such as CT scans, legacy exposures from nuclear weapons production and nuclear waste management, and new sources of exposure such as rare earth element and lithium mining, among others. The report says research on the health effects of low-dose radiation in the U.S. is limited and fragmented, lacking leadership, central coordination, and an overarching strategic agenda. While this research was managed in the past by the U.S. Department of Energy’s Office of Science, the office’s focus has been redirected.

“There is much we don’t know about the impacts of low-dose radiation exposures on our health — but recent advances in research, new tools, and a coordinated multidisciplinary research program could help us fill those gaps,” said Joe W. Gray, professor emeritus of laboratory medicine at the University of California, San Francisco, and chair of the committee that wrote the report. “This is especially important as science seeks to provide answers to concerned individuals and to communities that have been involuntarily exposed to radiation, including Indigenous communities, atomic veterans, nuclear workers, and others impacted by the legacy of U.S. nuclear weapons testing and production.”

A Coordinated Research Program
Significant investments over a sustained period spanning more than a decade will be required in order to develop and maintain a low-dose radiation research program, with periodic reassessments based on how research is progressing. The $5 million appropriated for the DOE’s low-dose radiation program in 2021 and 2022 is not sufficient even to initiate a coordinated federal research program, the report says. With adequate funding, DOE could implement most of the research program’s essential elements identified in the report within two years.

The research agenda proposed by the report extends beyond any single agency’s capabilities at present, and would involve coordination across federal agencies and national and international partners. The committee supported leadership of this coordination by both DOE and the National Institutes of Health — with DOE leading a portion of the strategic research related to computational and modeling research, and NIH leading the epidemiological and biological research.

The report notes concerns raised by some communities about DOE’s inherent conflicts because of its work with the nuclear weapons program and its role in promoting nuclear technologies, as well as concerns from the research community about DOE’s shortcomings related to management of the previous program. NIH is widely trusted by the scientific community, has well-established and transparent processes for funding research, and has no perceived conflicts of interest. Within NIH, the National Institute of Allergy and Infectious Diseases’ Radiation and Nuclear Countermeasures Program, the National Cancer Institute, and the newly conceptualized Advanced Research Projects Agency for Health (ARPA-H) could contribute to innovative low-dose radiation research leadership.

The report also recommends elements of a research program that should be incorporated into management of the low-dose program including a long-term commitment to the research, scientific independence, and transparency and engagement with impacted communities.

Research Priorities
The report sets priorities for epidemiological and biological research on low-dose radiation, as well as for establishing a research infrastructure. A revitalized radiation research program would be able to leverage recent scientific breakthroughs — such as greater computing power, genetic research, and data sharing systems — that previous research did not.

  • Epidemiological research should improve our estimation of the risks for cancer and other health outcomes, determine factors that can modify these effects — such as genetics or lifestyle — and develop better analytical tools.
  • Biological research should define the dose-response relationships for low radiation exposure, linking specific doses of radiation to health effects on the cellular level and the progression of disease. This research should also identify the effects of radiation on cellular and molecular features in order to establish causal links to adverse health effects, among other priorities.
  • Developing a research infrastructure should include creating tools for sensitive detection of radiation and precise characterization of cell and tissue changes, harmonizing research databases, and ensuring researchers’ access to low-dose exposure facilities.

New information gleaned by the research program can help inform estimates of the economic impact of possible changes to radiation protection standards and guidance. As there are no comprehensive estimates of the economic impact of current regulations, the committee was not able to estimate those of the proposed radiation research program.

The study — undertaken by the Committee on Developing a Long-Term Strategy for Low-Dose Radiation Research in the United States — was sponsored by the U.S. Department of Energy.


Prestigious Health Physics Society Fellowships and Travel Grants awarded to RED² students

The Health Physics Society has awarded four prestigious fellowships and five travel grants to doctoral and undergraduate researchers in the RED² Laboratory led by Dr. Dewji in the Nuclear and Radiological Engineering and Medical Physics Programs of the George W. Woodruff School of Mechanical Engineering at the Georgia Institute of Technology. Each of the Travel Grants supports travel to the 67th Annual Meeting of the Health Physics Society held July 17-21, 2022 in Spokane, WA, and each of the graduate fellowships awards $5000 to each recipient, with Travel Grant support to attend the 2023 Annual Meeting of the Health Physics Society.

Dr. Dewji was a prior recipient of the Richard J. Burk, Jr. Fellowship in 2008. “This is a very proud moment for me. My participation in the Health Physics Society pivoted and cultivated my entire career towards a field of scientific research and societal impact, the scope of which I had never fathomed as I embarked on my academic journey, only further catalyzed by my own mentor and adviser, Dr. Nolan Hertel (Past President of the Health Physics Society). Now, as a professor of nuclear engineering at Georgia Tech with a research focus in radiation protection and health physics, as well as a prior recipient of the Health Physics Society’s Elda E. Anderson Award and Member-Elect of the Health Physics Board of Directors, I have only high expectations for my students to grow into future leaders and ambassadors of the Health Physics Society given such incredible opportunities”.

Congratulations to the following recipients of Health Physics Society Fellowships and Travel Grants for the 2022-2023 year:

  • Dmitri Margot (Ph.D. student – GT NRE) – 2022 Health Physics Society Travel Grant; Health Physics Society Robert Gardner Memorial Fellowship
  • Heechan Lee (Ph.D. student – GT NRE) – 2022 Health Physics Society Travel Grant; 2022-2023 Health Physics Fellowship
  • Ignacio Bartol (Ph.D. student – GT NRE) – 2022 Health Physics Society Travel Grant; 2022-2023 Health Physics Society Robert Gardner Memorial Fellowship
  • Emmanuel Matey Mate-Kole (Ph.D. student – GT NRE) – 2022 Health Physics Society Travel Grant; Health Physics Society J Newell Stannard Fellowship
  • Matthew Louis (Undergraduate student – GT NRE) – 2022 Health Physics Society Travel Grant;

Navigate over to Undergraduate Students and to Graduate Students to meet each of these energetic, future leaders in health physics and over to Research Projects to learn about the exciting research each of the RED² students are engaging in radiation protection sciences and health physics.

2022 Health Physics Society award recipients: (Top left-to-right) Dmitri Margot, Heechan Lee; (Bottom left-to-right) Ignacio Bartol, Emmanuel Matey Mate-Kole, Matthew Louis.

The Health Physics Society (HPS), formed in 1956, is a scientific organization of professionals who specialize in radiation safety. Its mission is to support its members in the practice of their profession and to promote excellence in the science and practice of radiation safety.
Today its members represent all scientific and technical areas related to radiation safety, including academia, government, medicine, research and development, analytical services, consulting, and industry in all 50 states and the District of Columbia. The Society is chartered in the United States as an independent nonprofit scientific organization and, as such, is not affiliated with any government or industrial organization or private entity.

Updates to Radionuclide Patient Release: I-131 Age-Specific Dose and Exposure Rate Coefficients

How does applying the latest radiation biokinetic and dosimetric models compare to traditional methods used by licensees for radionuclide therapy patient release – inclusive of age-specific patients and members of the public? Have a look at the latest publication by RED² Laboratory’s Landon Aziz, in the journal, Radiation Protection Dosimetry. Aziz is now putting his expertise to practice as a medical health physicist at Houston Methodist Hospital.

Updates to prior models established for adult I-131 to reflect age-specific biokinetic and dosimetric models for patient release calculations reflective of age-specific patients and members of the public.

Updated effective dose rate and exposure rate coefficients for age-specific receptors representing members of the public were computed for external exposures from age-specific patients administered I-131 to treat thyroid dysfunction for patient release evaluation. Coefficients were compared to the simplified point source method described by United States Nuclear Regulatory Commission Regulatory Guide (RG) 8.39, which does not consider age-specific parameters, morphometry or time-dependent 131I biodistribution. Monte Carlo age-specific phantom simulations were correlated with modified continuous voiding patient biokinetic models approximating age-specific dose and exposure rates as a function of time postadministration. Dose rates resulted in an overapproximation by a factor of ~3 from differentiated thyroid cancer patients (5% uptake) and by ~2 from hyperthyroid patients (80%) at 8 h postadministration compared to RG8.39. This study provides a paradigm where age-specific morphometry and biokinetic integration must be jointly considered when developing patient release guidelines for I-131 and future radionuclide therapies.

RED² Students win prestigious awards from American Nuclear Society and Department of Energy

Congratulations to Georgia Tech RED² Ph.D. Candidate in Nuclear Engineering, Andrew Rosenstrom, for being awarded the 2022-2023 American Nuclear Society Radiation Protection and Shielding Division Everitt P. Blizard Memorial Scholarship totaling $3000. The Everitt P. Blizard Memorial Scholarship was established by the Radiation Protection & Shielding Division in November of 1993 to recognize graduate students studying in the field of radiation protection & shielding (see here for further history of this prestigious scholarship). Learn more about Rosenstrom’s research in FLASH radiotherapy shielding project here and his research experience at SLAC.

Congratulations are also merited to RED² undergraduate researcher and  Georgia Tech undergraduate in Nuclear Engineering, Matthew Louis, for being awarded the FY2021 U.S. Department of Energy, Office of Nuclear Energy – University Nuclear Leadership Program Undergraduate Scholarship totaling $10,000 (announcement here). Learn more about Louis here.

Graduate students and/or Post-doctoral fellows being sought to join RED²

Either 2 graduate students (with MS experience seeking Ph.D.) or 2 post-doctoral position hires are being sought for Summer-Fall 2022 (June/July/August 2022) start in my research group at Georgia Tech in the fields of CFD and biokinetics/PBPK. The official postings will be available in the coming weeks.


Please share these opportunities for qualified prospective Ph.D. students or postdoctoral researchers. Only candidates with appropriate qualifications as listed in the descriptions will be considered.

Post-doc candidates – please send support material in the meantime to me at;

Graduate students – please send unofficial transcript, CV, and e-mail expressing interest (in lieu of cover letter), and 1-2 appropriately relevant journal publications if available to me at


#biokinetics #countermeasures #internaldosimetry #cfd #cfpd #pbpk#hiring #students #postdocposition

In a “FLASH”! Meet RED² Ph.D. Student – Andrew Rosenstrom

RED² Ph.D. student, Andrew Rosenstrom, shares his research and goals as part of his work at SLAC on FLASH radiotherapy.

As part of a collaboration between RED² Laboratory and Stanford Linear Accelerator Center (SLAC), Ph.D. student, Andrew Rosenstrom is onsite at SLAC investigating new applications of high energy accelerator physics with new modalities in FLASH radiotherapy.

Catch up with Andrew as he describes his exciting research activities at SLAC.

  1. Please describe your project(s) work you conducted in the RED²  Laboratory. Include any details on the scientific/technical challenges you were tasked with addressing and limitations on current approaches that prompted your investigation.

My work as a part of the RED²  group is to design and optimize FLASH radiotherapy components for a preclinical system to inform radiation biology research and design parameters for a clinical FLASH radiotherapy device. The FLASH radiotherapy system in question uses high energy bremsstrahlung radiation (>10 MeV) while previous photon-driven FLASH systems have used photon energies <250 keV. Due to the higher photon energies and high workload, adverse secondary radiation, photoneutrons and capture gamma rays, are generated with relatively high fluences compared to radiotherapy machines that use conventional dose rates; shielding methodologies are needed to efficiently shield the primary and secondary radiation from preclinical and clinical FLASH radiotherapy machines to minimize extraneous doses to the patient, the operator and the public. Additionally, collimator components, which shape the photon beam and subsequently, the dose distribution in the sample, need to be optimized to meet certain experimental criteria while maximizing the dose rate in the desired region.  By increasing the dose rate as high as possible, the experimenters will have greater flexibility to perform experiments in order to understand the underlying biological mechanisms of the FLASH effect.

2. What scientific/technical tools/methods did you use/learn to conduct your investigation?

My work deals primarily with Monte Carlo radiation transport using the code FLUKA. As a part of my work, I have continued to gain proficiency in conducting efficient and accurate simulations as well as more complex aspects of radiation transport through the use of FLUKA’s user-routines.

In order to perform the optimization of the beam shaping components of the collimator, I have learned how to use heuristic methods, namely Genetic and Nelder-Mead simplex search algorithms, as well as how to address the challenges faced by algorithms in optimization: proving optimality, completeness of the search, proving accuracy and precision of results, and computational efficiency.

3. What non-technical skills did you develop as a result of your experiences? Did you present at any conferences/win any awards?

Through my work, I have greatly improved my presentation skills, both speaking and slide design, performing weekly presentations with my research group. I have also presented my work at several conferences and have won second place at the Texas HPS conference.

Andrew Rosenstrom and SLAC mentor, Dr. Mario Santana Leitner, suiting up for a facility walkthrough.

4. What do you believe will be the impact of your work  – scientifically? In your academic goals?

I believe my work will help to inform the design of clinical FLASH machines that use high energy bremsstrahlung radiation to deliver dose. Beyond radiation protection, the work involving FLASH radiotherapy has the potential to provide better patient outcomes and expanded access for external beam radiotherapy treatments.

5. Looking ahead, what are your professional and/or technical goals?

My long-term professional goal is to become the Radiation Safety Officer of a national laboratory. This role would require technical proficiency, and intuition for all aspects of radiation protection systems. Being in this role at a national laboratory would provide access to cutting edge applications that involve radiation and would be very exciting as well as a real challenge.


RED² Investigates Radiation Doses from Improvised Nuclear Devices

In the event of exposure or dose construction involving an improvised nuclear device (IND), RED² Ph.D. students Andrew Rosenstrom and Ethan Asano used the latest computational human phantom models from University of Florida/National Cancer Institute series and Monte Carlo radiation transport code to compute organ dose coefficients from the prompt neutron and gamma-ray fields from an IND. Results were recently published in a peer-reviewed journal manuscript in the journal, Radiation Research, in collaboration with Keith Griffin and Dr. Choonsik Lee at the National Cancer Institute and Dr. David Hooper at Oak Ridge National Laboratory.

Representative radius from an IND detonation.

In this work, the  voxel phantom series including  newborn, 1-, 5-, 10-, 15-, and 35-year-old male and female models based on International Commission on Radiological Protection physiological parameters were used to compute organ and effective dose coefficients. Dose coefficients have prior been calculated for epidemiological purposes specifically to the studied population from the 1945 Japanese cohort. Dose assessment using the lastest models in radiation protection have not yet been harnessed to provide an assessment for a more representative reference population.


Age- and sex-specific reference phantom models from UF/NCI used in the study to compute prompt neutron and photon organ and effective dose coefficients in this study.

Source irradiation was simulated using Monte Carlo N-Particle transport code version 6.2 to determine organ dose coefficients under four idealized irradiation geometries at three distances from the detonation hypocenter at Hiroshima and Nagasaki using the corrected DS/02 free-in-air prompt neutron and photon fluence spectra as a representative surrogate source term of a low-yield IND. Through these simulations, age-specific dose coefficients were determined for individual organs.

PIMAL phantom in postures beyond upright used to determine the variability between upright and articulated postures in dose estimation and reconstruction.

The effect of posture were additionally simulated to determine the effect of posture on dosimetric estimation and reconstruction, drawing upon prior work by RED² .

Results demonstrated that that Cs-137 and the Watt fission spectrum are not ideal general surrogate sources for fission weapons, which may be considered for experimental testing of medical countermeasures and other dose/dose rate reproduction activities.

The data produced can be implemented in nuclear emergency response and defense for higher fidelity estimation of radiation detriment to a reference population.

Check out the latest publications by RED²  here!