2024 - Versant Medical Physics and Radiation Safety

23 Sep 2024

Dr. Thomas Morgan: An Inspirational Impact on Health Physics

Dr. Thomas Morgan, a Senior Health Physicist with Versant Physics, was recently made a Fellow by the Health Physics Society. As a long-standing scientist within the world of radiation science and health physics, this is an achievement he more than deserves. A 1983 graduate of the University of California, Irvine, Dr. Morgan has built a distinguished career spanning several decades. His academic and professional achievements reflect a deep commitment to advancing the field and training future generations of scientists.

Academic Foundations and Early Training

Dr. Morgan’s academic path laid a strong foundation for his future contributions to radiation science. At UC Irvine, he earned bachelor’s degrees in both biology and chemistry. These disciplines provided him with a robust understanding of the scientific principles underlying medical physics and radiological sciences. Dr. Morgan’s educational journey didn’t stop there. He continued at UC Irvine to obtain both a master’s degree and a Ph.D. in radiological sciences, specializing in medical physics.

During his time as a graduate student, Dr. Morgan underwent rigorous training in operating nuclear reactors. He became licensed by the Nuclear Regulatory Commission as a Senior Operator of the TRIGA Mk 1 nuclear reactor on campus. This hands-on experience with nuclear technology and safety would become a cornerstone of his career.

Contributions to Research and Publications

Dr. Morgan’s research contributions are significant and varied. His work spans several critical areas, including radiation biology and physics, cancer biology, clinical cancer research, and radiation safety. Over the years, he has directed and conducted valuable research. This work has advanced our understanding of how radiation affects biological systems. The research also produced options for how it can be used safely and effectively in medical treatments.

The scholarly output of Dr. Thomas Morgan is impressive, with more than 35 peer-reviewed publications to his name. Additionally, he has co-authored three books and six book chapters. This further solidifies his reputation as a leading expert in his field. In the Versant Physics newsroom, we covered the publication of one of his more recent publications with HPS. Publications like these not only reflect his deep knowledge but his dedication to sharing that knowledge with the broader scientific community.

Commitment to Education and Training

Dr. Morgan’s commitment to education is evident from his extensive teaching experience. He was hired by the Southern California Permanente Medical Group in Los Angeles, California, to teach radiation biology resident physicians in the Radiation Therapy Department. He was appointed as an Adjunct Professor of Health Sciences at California State University of Long Beach. This was where he taught radiation biology to radiation therapy radiologic technologists. Dr. Morgan took every role in educating these future professionals with determination to better the future. This underscores his belief in the importance of training and mentoring the next generation of radiation practitioners.

Dr. Thomas Morgan also taught health physics to medical physics graduate students at Columbia University in New York City. There he served as an Adjunct Professor of Applied Physics and Mathematics. Through these roles, Dr. Morgan has not only imparted his knowledge but has also helped shape the careers of the next generation of medical physicists.

Professional Roles Through a Dedicated Career

Dr. Morgan’s professional career includes several prestigious positions in radiation safety and environmental health. He served as the Radiation Safety Officer (RSO) at the Southern California Permanente Medical Group’s Los Angeles campus. Dr. Morgan was also the RSO at the University of Rochester and Strong Memorial Hospital in Rochester, New York. His expertise in managing radiation safety protocols in these settings was crucial for maintaining safe and compliant operations.

Before his retirement in 2018, Dr. Morgan held a prominent role as the Executive Director of Environmental Health and Safety and Chief Radiation Safety Officer at Columbia University and the Columbia University Irving Medical Center. In this capacity, he was responsible for overseeing all aspects of environmental health and safety. This included radiation safety, ensuring that the institution adhered to the highest standards.

Leadership in Professional Organizations

Dr. Morgan’s contributions extend beyond his research and teaching. He has always been an active member of the Health Physics Society. Dr. Morgan even served as past president of the Western New York and Florida chapters. His leadership roles also include chairing several committees and serving as a Director of the Society. In recognition of his service and contributions to the field, he was named a Fellow of the Health Physics Society in 2023.

His editorial roles further illustrate his commitment to advancing the field. Dr. Morgan is currently an Associate Editor of the Health Physics Journal. He also previously served as an Associate Editor of Applied Physics Research. These positions highlight his ongoing engagement with the latest research and developments in health physics.

Certification and Licensure

Dr. Morgan’s professional qualifications are extensive. He is certified by the American Board of Health Physics in the practice of comprehensive health physics and is licensed to practice medical health physics in New York, Florida, and Texas. These credentials underscore his expertise and commitment to maintaining the highest standards in his practice.

Personal Life and Volunteer Work

Outside of his professional life, Dr. Morgan enjoys residing in Sarasota, Florida, with his wife, Diane. He remains actively involved in his community through volunteer work. He serves as a docent at the Mote Marine Laboratory, where he helps educate the public about marine science. Additionally, his involvement with the Manasota Medical Reserve Corps reflects his dedication to supporting public health and safety.

A Continuing Devotion to Radiation Science and Health Physics

The career of Dr. Thomas Morgan is a testament to his passion for radiation science and health physics. From his early academic achievements to his significant research contributions, teaching roles, and leadership positions, his impact on the field is profound. His dedication to education, professional service, and community involvement underscores a lifetime of commitment to advancing science and improving safety. As a newly named Fellow of the Health Physics Society, Dr. Morgan’s legacy continues to inspire and shape the future of radiation science.

29 Aug 2024

Cancer Treatment, Nuclear Medicine Versant Physics 0 comment

Celebrating the Achievements of Dr. Darrell R. Fisher: A Journey of Scientific Excellence

Earlier this year, the Columbia Chapter of Health Physics Society and the Georgian Health Physics Association nominated Dr. Darrell R. Fisher for the 2024 Distinguished Scientific Achievement Award of the Health Physics Society (HPS). Fisher is a nuclear medicine physicist with Versant Medical Physics and Radiation Safety. He received the Distinguished Scientific Achievement Award in July 2024, during the 16^th International Congress of the International Radiation Protection Association and 69^th HPS Annual Meeting in Orlando, Florida. The award recognized Dr. Fisher’s scientific contributions over a career spanning more than five decades in applied radiation safety sciences, including internal dosimetry, radiobiology, radiochemistry, and design and testing of radiopharmaceuticals and medical devices. His innovative research has led to numerous significant advancements in the applied radiation health sciences.

Discoveries in Chelation Therapy and Radiotoxicity

One of Dr. Fisher’s early discoveries was identifying the toxicity and congenital birth defect teratogenicity of the heavy-metal chelating agent CaNa₃DTPA compared to the non-toxic ZnNa₃DTPA. This research showed the importance of maintaining cellular zinc and manganese availability during critical growth periods to ensure uninterrupted cell division. His work was instrumental in enhancing the safety and effectiveness of emergency decorporation therapy for nuclear workers accidentally exposed to plutonium, neptunium, and americium. By establishing the safety of ZnNa₃DTPA, Dr. Fisher’s work paved the way for safe and effective treatments after actinide contamination events, significantly impacting emergency response protocols and worker safety in nuclear industry.

Advances in Applied Microdosimetry

Dr. Fisher performed the first microdosimetry calculations for plutonium-238 and plutonium-239 in beagle dog lung tissue specimens. His research disproved the “hot particle hypothesis” claimed by Thomas Cochran and Arthur Tamplin; Fisher showed that their hypothesis could not be supported by dosimetry or radiobiology. Fisher described the fundamental science underlying relative biological effectiveness (RBE) relationships between alpha-particle dose and two critical biological endpoints: cellular mutation and primary DNA damage. This work demonstrated that varying the specific activity and spatial geometry of plutonium microsphere sources could result in vastly different biological outcomes at constant absorbed dose. These findings were pivotal to better understanding radiation effects at the microscopic level, influencing safety standards, and advancing what would later become new cancer treatment approaches with alpha-emitting radionuclides.

Innovations in Cancer Treatment

Dr. Fisher was an early proponent of short-lived alpha emitters such as radium-223 and actinium-225 for cancer treatment. He performed the first cellular-level microdosimetry calculations for alpha-emitter-radiolabeled monoclonal antibodies used in cell-targeted radioimmunotherapy. His pioneering work in developing treatment-planning dosimetry for clinical radioimmunotherapy supported the high-dose treatment of relapsed lymphoma, leukemia, and multiple myeloma patients. In the laboratory, he helped to develop and test several innovative alpha-emitter complexing agents, including macrocyclic cages and nanoparticle delivery constructs for next-generation therapies.

Contributions to Uranium Toxicology

Dr. Fisher’s assessments of dosimetry and health effects from uranium intakes led to a modified biokinetic model for inhaled uranium hexafluoride compounds. His research provided crucial insights following the Sequoyah Fuels accident in Oklahoma, where workers were exposed to uranium hexafluoride. Dr. Fisher’s model improved the understanding of uranium’s behavior in the body, leading to better understanding of uranium toxicity.

Pioneering Work in Radionuclide-Polymer Composites

Dr. Fisher conceived, designed, patented, and tested novel radionuclide-polymer composites employing insoluble crystalline yttrium-90-phosphate microspheres administered in a thermo-reversible hydrogel delivery matrix. This innovation has enabled direct interstitial therapy of nonresectable solid tumors, providing new avenues for cancer treatment in both humans and veterinary animals. Precision radionuclide therapy by direct intra-tumoral injection maximizes therapeutic ratios, a key measure of treatment safety and efficacy. His work has enabled highly efficient delivery of radiation to tumors, minimizing damage to surrounding healthy organs and tissues and associated side-effects of radiation therapy.

Enhancing Patient Safety in Nuclear Medicine

Dr. Fisher helped develop and published practical methods for patient-specific dosimetry to characterize the severity of inadvertent radiopharmaceutical extravasations in diagnostic and therapeutic nuclear medicine. Fisher has specialized in medical internal radiation dosimetry, an essential element of managing patient safety and improving therapy outcomes.

Lifelong Commitment to Radiation Safety

Darrell Fisher’s journey in health physics began in 1973 as an undergraduate research assistant at the University of Utah’s Radiobiology Laboratory. His early research on extracting americium-241 from skeletal surfaces in live mice laid the foundation for his future contributions to radiation safety and radiobiology. Over the years, his work has led to significant advancements in understanding and mitigating the effects of radiation exposures in medical and occupational settings. His dedication to the field is evident in his continuous efforts to improve safety standards, develop innovative treatment methods, and educate future generations of health physicists.

The 2024 Distinguished Scientific Achievement Award recognizes Dr. Fisher’s commitment to scientific excellence and discovery for work that not only advances scientific knowledge but also improves patient care and radiation safety. His diverse contributions to the field of applied radiation safety sciences, in collaboration with highly respected research associates and colleagues worldwide, have been impactful. His innovative research, spanning over 50 years, has led to significant advancements in worker safety, dosimetry and microdosimetry, radionuclide therapy treatment planning, direct interstitial treatment of inoperable tumors, and patient safety in nuclear medicine.

27 Mar 2024

Airplane flight crew character design. Pilot and stewardess flat vector illustration

Background Radiation, Health Effects, Ionizing Radiation, Radiation Safety Versant Physics 0 comment

Flight Crews and Radiation Exposure

Flight crews are among the occupational groups most exposed to ionizing radiation, with an average annual effective dose surpassing that of other radiation-exposed workers in the United States, excluding astronauts.¹ This elevated exposure is primarily due to the high levels of cosmic radiation encountered at flight altitudes, which can pose significant health risks to pilots and cabin crew members.² In this blog post, we’ll explore the nature of cosmic radiation, its potential health effects, current exposure levels for aircrews, as well as the guidelines and regulations in place to ensure their safety.

What Is Cosmic Ionizing Radiation?

As we’ve touched on in a previous blog, cosmic ionizing radiation–or simply cosmic radiation–originates from beyond Earth’s atmosphere. Additionally, it consists of two main components: galactic cosmic radiation (GCR) and solar particle events (SPEs).³^,⁴

Galactic Cosmic Radiation

GCR is a constant background radiation that permeates interstellar space, originating from distant stars and galaxies. It is composed primarily of high-energy protons (85%) and alpha particles (14%). There is also a small fraction of heavier nuclei (1%) ranging from lithium to iron and beyond. These particles span a wide energy range, and as a result some reach extremely high energies capable of penetrating deep into the Earth’s atmosphere and passing through aircraft shielding.⁵

Solar Particle Events (Solar Flares)

Solar particle events, on the other hand, are sporadic bursts of intense radiation associated with solar flares and coronal mass ejections. During an SPE, the Sun ejects a large number of high-energy protons and other particles that can reach Earth within hours to days. While less frequent than GCR, SPEs can dramatically increase radiation exposure for flight crews, particularly those on polar routes where the Earth’s magnetic field provides less protection.⁶^,⁷

At higher altitudes, such as those typically encountered during air travel, the Earth’s atmosphere provides less shielding against cosmic radiation, resulting in increased exposure for flight crews and passengers.

Several studies that have investigated the difference in cosmic ray levels at various altitudes versus ground level found that the dose rate of cosmic radiation at a cruising altitude of 30,000 feet was approximately 10 times higher than at sea level.

The specific increase in cosmic ray exposure at higher altitudes is influenced by several factors, including the solar cycle (solar maximum vs. solar minimum), geomagnetic field strength, and also the path of the flight (polar routes are exposed to higher levels of cosmic rays). For example, during periods of high solar activity (solar maximum), the increased solar wind can actually shield the Earth from some cosmic rays, slightly reducing the exposure at high altitudes. Conversely, during a solar minimum, the cosmic ray intensity can be higher.

Estimates of the number of hours that have to be flown in order to receive an effective dose of 1 mSv at 30,000 feet are 510 hours at a latitude of 30^o South and 1,330 hours at the equator.⁸

Health Effects and Uncertainties

The health risks associated with radiation exposure are generally well-documented. Prolonged exposure to high levels of radiation can increase the risk of cancer, cataracts, as well as other adverse health effects. However, quantifying the specific risks associated with the chronic low-dose radiation experienced by flight crews remains a challenge.

The World Health Organization’s International Agency for Research on Cancer (IARC) acknowledges that ionizing radiation causes cancer in humans and is also associated with reproductive problems. However, when it comes to cosmic ionizing radiation, several uncertainties remain:

Cancer Risk: Most radiation health studies have focused on groups exposed to much higher doses from different types of radiation (such as atomic bomb survivors or patients receiving radiation therapy).⁹ Due to this, the specific link between cosmic ionizing radiation and cancer risk is not yet fully understood.
Reproductive Health: Miscarriages and birth defects related to cosmic radiation exposure are still not definitively established.¹⁰

Despite the limitations of current research, several studies have suggested that flight crews may have a higher incidence of certain cancers compared to the general population. These include breast cancer, melanoma, as well as non-melanoma skin cancers.¹¹^,¹² However, the causal link between cosmic radiation exposure and these increased risks has not been definitively established. Other factors, such as lifestyle and genetic predisposition, may also play a role.¹³

Exposure Levels for Flight Crews

Recent dose and risk assessments by a wide variety of investigators have demonstrated the need to dedicate further attempts to quantify potential radiation exposure.¹⁴ The National Council on Radiation Protection and Measurements (NCRP) reports an average annual effective dose of 3.07 mSv for flight crews; most of this exposure comes from natural radiation:

Estimates of annual aircrew cosmic radiation exposure range from 0.2 to 5 millisieverts (mSv) per year depending on factors such as flight routes, altitude, and solar activity.
Solar particle events occur less frequently, but during events, exposure levels can increase substantially and potentially lead to higher doses over short periods.

Guidelines and Regulations

While there are no official dose limits specifically for aircrew in the United States, national and international guidelines provide context:

International Commission on Radiological Protection (ICRP): Recognizes aircrew as radiation-exposed workers. They also recommend an effective dose limit of 20 mSv per year averaged over 5 years (totaling 100 mSv in 5 years) for radiation workers. However, for the general public, the recommended limit is 1 mSv per year.¹⁵
Pregnant Aircrew: The ICRP recommends a dose limit of 1 mSv throughout pregnancy.¹⁶

Current regulations aim to limit radiation exposure for flight crews, but there is room for improvement. The International Commission on Radiological Protection (ICRP) sets guidelines for radiation protection and also includes dose limits for occupational exposure. However, these guidelines may not adequately address the unique challenges faced by flight crews. To improve current radiation safety regulations for aircrews, a multi-faceted approach is necessary. This should include:

Improved Monitoring and Data Collection

Implementing advanced radiation monitoring systems on aircraft in addition to encouraging the use of personal dosimeters by flight crews can provide more accurate and comprehensive data on exposure levels¹⁷. This information can help refine risk assessments as well as guide the development of more effective protection strategies.

Aircraft Shielding and Design

Continued research into advanced shielding materials in addition to aircraft design modifications can help reduce the radiation dose received by flight crews and passengers¹⁸. This may also involve the use of novel composite materials or the incorporation of additional shielding in critical areas of the aircraft.

Route Optimization and Flight Planning

By carefully planning flight routes and altitudes, airlines can minimize exposure to cosmic radiation, particularly during solar particle events¹⁹. This may also involve rerouting flights to lower latitudes or reducing flight time at higher altitudes when necessary.

Education and Awareness Programs

Providing flight crews with comprehensive information about the risks of cosmic radiation exposure in addition to the importance of proper protection measures can empower them to make informed decisions about their health and safety²⁰. This should include training on the use of personal protective equipment, such as dosimeters, as well as guidelines for managing exposure during pregnancy.

Regulatory Harmonization and Enforcement

Strengthening international collaboration to harmonize radiation protection standards for flight crews in addition to ensuring consistent implementation and enforcement of these standards across the aviation industry can help create a safer working environment for all aircrews²¹²¹.

Conclusion

Although no regulations officially set dose limits, radiation exposure is still a concern to be evaluated for airplane flight crews due to their occupational exposure to cosmic radiation. While the specific health risks associated with this chronic low-dose exposure remain uncertain, continued efforts are essential ensure a safe working environment. By implementing measures such as personal dosimetry devices, increased monitoring, staff training, and encouraging airplane manufacturers to consider shielding and design modifications, airlines can better protect their flight crews. Ensuring a safer career for every radiation worker will require time, dedication, and collaboration. However, the benefits for the health and safety of all industries, including aircrews, make it a worthwhile endeavor.

Versant Physics is a full-service medical physics and radiation safety consulting company based in Kalamazoo, MI. Contact us for all of your regulatory, radiation safety, and personnel dosimetry needs.

Sources

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Year: 2024