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23 Sep 2024
Graphic of someone teaching physics.
Health Physics, Nuclear Medicine, Radiation Safety Versant Physics 0 comment

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

Headshot of Dr. Tom Morgan.

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.

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 30o 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:

  1. 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.
  2. 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

  1. Friedberg, W., & Copeland, K. (2003). What aircrews should know about their occupational exposure to ionizing radiation. Oklahoma City, OK: Civil Aerospace Medical Institute, Federal Aviation Administration. ↩︎
  2. United Nations Scientific Committee on the Effects of Atomic Radiation. (2008). Sources and effects of ionizing radiation: UNSCEAR 2008 report to the General Assembly, with scientific annexes. New York: United Nations. ↩︎
  3. Validation of modelling the radiation exposure due to solar particle events at aircraft altitudes. Radiation Protection Dosimetry, Volume 131, Issue 1, August 2008, Pages 51–58. https://doi.org/10.1093/rpd/ncn238 ↩︎
  4. Wilson, J. W., Townsend, L. W., Schimmerling, W., Khandelwal, G. S., Khan, F., Nealy, J. E.,  & Norbury, J. W. (1991). Transport methods and interactions for space radiations. NASA Reference Publication, 1257 ↩︎
  5. O’Sullivan, D. Exposure to galactic cosmic radiation and solar energetic particles. Radiat Prot Dosimetry. 2007;125(1-4):407-11. https://pubmed.ncbi.nlm.nih.gov/17846031/ ↩︎
  6. Turner, R. E. (2007). Solar particle events from a risk management perspective. Radiation Protection Dosimetry, 127(1-4), 534-538. ↩︎
  7. Lantos, P., & Fuller, N. (2003). History of the solar particle event radiation doses on-board aeroplanes using a semi-empirical model and Concorde measurements. Radiation Protection Dosimetry, 104(3), 199-210. ↩︎
  8. Cosmic Radiation Exposure for Casual Flyers and Aircrew, https://www.arpansa.gov.au/understanding-radiation/radiation-sources/more-radiation-sources/flying-and-health ↩︎
  9. National Research Council. (2006). Health risks from exposure to low levels of ionizing radiation: BEIR VII phase 2 (Vol. 7). National Academies Press. ↩︎
  10. CDC – Aircrew Safety and Health – Cosmic Ionizing Radiation – NIOSH Workplace Safety & Health Topics. Centers for Disease Control and Prevention. Published 2019. https://www.cdc.gov/niosh/topics/aircrew/cosmicionizingradiation.html ↩︎
  11. Pukkala, E., Aspholm, R., Auvinen, A., Eliasch, H., Gundestrup, M., Haldorsen, T., & Tveten, U. (2003). Cancer incidence among 10,211 airline pilots: a Nordic study. Aviation, Space, and Environmental Medicine, 74(7), 699-706. ↩︎
  12. Rafnsson, V., Hrafnkelsson, J., & Tulinius, H. (2000). Incidence of cancer among commercial airline pilots. Occupational and Environmental Medicine, 57(3), 175-179. ↩︎
  13. Hammer, G. P., Blettner, M., & Zeeb, H. (2009). Epidemiological studies of cancer in aircrew. Radiation Protection Dosimetry, 136(4), 232-239. ↩︎
  14. Olumuyiwa A. Occupational Radiation Exposures in Aviation: Air Traffic Safety Systems Considerations. International Journal of Aviation, Aeronautics, and Aerospace. Published online 2020. doi:https://doi.org/10.15394/ijaaa.2020.1476 ↩︎
  15. International Commission on Radiological Protection. (2007). The 2007 recommendations of the International Commission on Radiological Protection. Annals of the ICRP, 37(2-4), 1-332. ↩︎
  16. International Commission on Radiological Protection. (2000). Pregnancy and medical radiation. Annals of the ICRP, 30(1), iii-viii, 1-43. ↩︎
  17. Bartlett, D. T. (2004). Radiation protection aspects of the cosmic radiation exposure of aircraft crew. Radiation Protection Dosimetry, 109(4), 349-355. ↩︎
  18. Wilson, J. W., Miller, J., Konradi, A., & Cucinotta, F. A. (1997). Shielding strategies for human space exploration. NASA Conference Publication, 3360. ↩︎
  19. Copeland, K. (2014). Cosmic radiation and commercial air travel. Radiation Protection Dosimetry, 162(3), 351-357. ↩︎
  20. International Civil Aviation Organization. (2012). Manual of Civil Aviation Medicine. https://www.icao.int/publications/Documents/8984_cons_en.pdf ↩︎
  21. International Atomic Energy Agency: Cosmic radiation exposure of aircrew and space crew. https://www.iaea.org/sites/default/files/20/11/rasa-cosmic.pdf ↩︎
18 Dec 2023
Large size motorized 3D water phantom system for dose distribution measurement of radiation therapy beams in real daily routine practice used as a part of quality control of radiation therapy.
Cancer Treatment, Dosimetry, Nuclear Medicine, Radiation Therapy, Uncategorized Versant Physics 0 comment

What’s Inside Matters Most: Internal Dosimetry

Medical physics has been an integral part of medicine and healthcare over the greater part of the last century. Applying physics theory, concepts, and methods, scientists have created patient imaging, measurement, and treatment techniques that revolutionized the medical world. One product of medical physics has been the evolving specialty called radiopharmaceutical dosimetry, the calculation of absorbed dose and optimization of radiation dose delivery in cancer treatment. Today, we address internal dosimetry, the subset of medical physics that aims to optimize treatment and protect the patient from any undesirable side effects.

What is internal dosimetry?

Dosimetry is the measurement of radiation energy imparted to body organs and tissues. Radionuclides emit beneficial ionizing radiation that is useful for both diagnostic imaging of various diseases as well as for cancer treatment. Thus, medical internal dosimetry is the assessment of internal radiation dose from incorporated radionuclides associated with such life-saving radiopharmaceuticals.1 Radiation dose is the amount of energy imparted by radiations emitted during disintegration of radioactive atoms that constitute part of the radiopharmaceutical chemistry. Dose to organs of the body is quantified per unit mass (or weight) irradiated tissue. Dosimetry provides the fundamental quantities needed for several important purposes, including record-keeping, radiation protection decision-making, risk assessment, and cancer-treatment planning.2 The purpose and objective is to optimize medical benefit while minimizing potential radiation damage to body cells, tissues, and organs.

Dosimetry is a complex physical and biological science. Internal dosimetry provides critical information needed to better understand the biological mechanisms governing radionuclide uptake, translocation, and excretion from the body. The radiation dose imparted depends on the type, amount, and distribution of radionuclides, as well as specific nuclear properties, such as energy emitted.

Internal dosimetry differs from “external” dosimetry, which deals with the radiation dose from sources outside the body. Devices such as dosimeters measure external dosimetry directly, while internal dosimetry relies on indirect methods of radioactivity inside the patient using bioassay and imaging measurements.3 Bioassay is the measurement of the activity or concentration of radionuclides in biological samples. Samples can include urine specimens, feces, blood, or breath. Imaging techniques, such as whole-body counters or gamma cameras, can detect the radiation emitted by the radionuclides inside the body. This helps to provide information on their location and quantity.1

When is internal dosimetry used in healthcare?

Internal dosimetry mainly benefits patients who receive radionuclide therapy, a treatment that involves administering radioactively labeled proteins, such as monoclonal antibodies, to target specific types of cancer.3 It also helps to evaluate and account for unique patient variations in biodistribution—the way that different subjects respond to treatment. Internal dose assessments analyze radionuclide behavior in both normal (healthy) organs, as well as tumors. For example, imaging measurements provide physicists with important information to determine tumor uptake, retention, and clearance. In doing so, administered activity can be tailored according to patient health status, age, size, sex, and basal metabolic rates.

How does internal dosimetry produce useful data?

The main challenge of internal dosimetry is to track and follow the uptake, redistribution, metabolism, and clearance of the administered radiopharmaceutical inside the body over extended time periods after administration.4 Tracking sometimes involves mathematical modeling to describe the absorption, distribution, metabolization, and excretion of radionuclides by the body. Biokinetic models may be developed from the study of population groups, knowledge of radionuclide behavior in different organs, and the unique chemistry of each radiopharmaceutical. Biokinetic models incorporate mathematical compartments representing a particular organ or a tissue, and descriptions of the transfer rates that reflect the movement of radionuclides from one body compartment to another.1

Summary

Internal dosimetry is an important tool for radiation protection, especially in the fields of nuclear medicine, occupational health, and environmental monitoring. Dosimetry helps to customize or personalize nuclear medicine in cancer patients. In a broader sense, internal dosimetry is also applied to occupational and environmental health to prevent or reduce the exposure to radionuclides, by providing information on the sources, pathways, and levels of intake, and by suggesting appropriate measures, such as respiratory protection, contamination control, or dose limits. Internal dosimetry can also help to verify the adequacy of workplace controls, to demonstrate regulatory compliance, and to provide medical and legal evidence in case of accidental or intentional exposure.

Special software tools have been developed for the clinical nuclear medicine setting to facilitate medical imaging and calculate internal doses.

QDOSE® Multi-purpose Voxel Dosimetry (Personalized Dosimetry in Molecular Radiotherapy) is a complete, one-stop solution software for all internal dosimetry needs with multiple parallel workflows. With USFDA 510(k) clearance granted in August 2023, QDOSE® has proven its quality and compliance. To learn more, visit our QDOSE® webpage or schedule a meeting with our team.

Sources

  1. Sudprasert W, Belyakov OV, Tashiro S. Biological and internal dosimetry for radiation medicine: current status and future perspectives. J Radiat Res. 2022;63(2):247-254. doi:10.1093/jrr/rrab119
  2. Bartlett R, Bolch W, Brill AB, et al. MIRD Primer 2022: A Complete Guide to Radiopharmaceutical Dosimetry. Society of Nuclear Medicine & Molecular Imaging; 2022.
  3. Chapter 7 External and Internal Dosimetry. Accessed November 15, 2023. https://www.nrc.gov/docs/ML1121/ML11210B523.pdf
  4. What is Internal Dosimetry – Definition. Radiation Dosimetry. Published December 14, 2019. Accessed November 16, 2023. https://www.radiation-dosimetry.org/what-is-internal-dosimetry-definition/

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13 Sep 2023
Supervisor use the survey meter to checks the level of radiation
Ionizing Radiation, Medical Physics, Radiation Safety, Radioactive Material Versant Physics 0 comment

The Units to Measure Radiation: Explained

The history of radiation units ties closely to the development of our understanding about radiation and its effects. The discovery of x-rays and radioactivity in the late 19th century by scientists like Wilhelm Roentgen, Henri Becquerel, and Pierre Curie paved the way for the exploration of radiation measurement.

As our knowledge of radiation’s effects on living organisms grew, the need for standardized units became evident. The roentgen was one of the earliest units to measure ionization, followed by the introduction of the curie to measure radioactivity. Over time, advancements in our understanding of radiation’s biological effects led to the development of units like the rem and the sievert.

Creating Radiation Units

The development of the SI system (International System of Units) established a standardized set of units to provide a coherent and universal way to measure radiation. The gray and the sievert were introduced as the primary units for absorbed dose and equivalent dose, respectively, within the SI system.

Four distinct yet interconnected units quantify radioactivity, exposure, absorbed dose, and dose equivalent. The mnemonic R-E-A-D creates a simple way to recall these units, which consist of a combination of commonly used (British, e.g., Ci) and internationally recognized (metric, e.g., Bq) units.1 Below, we will detail the mnemonic and discuss the history of the radiation units along with their relevant scientists:

Radioactivity defines the release of ionizing radiation from a substance. Whether it emits alpha or beta particles, gamma rays, x-rays, or neutrons, the radioactivity of a material is a measure of how many atoms within it decay over a specific period of time. The curie (Ci) and becquerel (Bq) units quantify radioactivity.1


Antoine Henri Becquerel was a French physicist, engineer, and Nobel laureate who discovered evidence of radioactivity. Becquerel’s earliest works centered on the subject of his doctoral thesis: the plane polarization of light, with the phenomenon of phosphorescence and absorption of light by crystals. Early in his career, Becquerel also studied the Earth’s magnetic fields. In 1896, Becquerel discovered evidence of radioactivity while investigating phosphorescent materials such as some uranium salts. For his work in this field, he shared the 1903 Nobel Prize in Physics with Marie Curie and Pierre Curie. The SI unit for radioactivity, becquerel (Bq), is named after him.2

The curie (Ci) unit was created in 1910 by the International Congress of Radiology to measure radioactivity. Pierre Curie, another French physicist, and his wife Marie Curie, who also sat on the committee that named the unit, were the inspirations for the name through their radioactive studies. The original definition of the curie was “the quantity or mass of radium emanation in equilibrium with one gram of radium (element)”.3 In 1975, the becquerel replaced the curie as the official radiation unit in the International System of Units (SI) where 1 Bq = 1 nuclear decay/second4. The relationship between the two units is 1 Ci = 37 GBq (giga becquerels).

Exposure quantifies the extent of radiation going through the atmosphere that reaches a person’s body or a material. Numerous radiation monitors gauge exposure, utilizing the units of roentgen (R) or coulomb/kilogram (C/kg).1

The roentgen is a legacy unit of measurement for the exposure of X-rays and gamma rays. This unit is defined as the electric charge freed by such radiation in a specified volume of air divided by the mass of that air and has the value 2.58 x 10-4 C/(kg air).5 It was named after Wilhelm Roentgen, a German physicist who discovered X-rays and was awarded the first Nobel Prize in Physics for the discovery.

In 1928, the roentgen became the first international measurement quantity for ionizing radiation defined for radiation protection. This is because it was, at the time, the most easily replicated method of measuring air ionization by using ion chambers.6 However, although this was a major step forward in standardizing radiation measurement, the roentgen had a disadvantage: it was only a measure of air ionization rather than a direct measure of radiation absorption in other materials, such as different forms of human tissue. As a result, it did not take into account the type of radiation or the biological effects of the different types of radiation on biological tissue. Consequently, new radiometric units for radiation protection came to be which took these concerns into account.7

The SI unit for measuring exposure to ionizing radiation is coulomb per kilogram (C/kg). Interestingly, unlike other SI radiation units, this unit does not have a specific name. It officially replaced the previous unit, the roentgen, in 1975, with a transition period of at least ten years.8 The SI unit of electric charge, the coulomb, was named in honor of Charles-Augustin de Coulomb in 1880. Charles-Augustin de Coulomb was a French physicist whose best-known work is his formulation of Coulomb’s law. This law states that the force between two electrical charges is proportional to the product of the charges and inversely proportional to the square of the distance between them. He also made important contributions to the fields of electricity, magnetism, applied mechanics, friction studies, and torsion.9

Absorbed dose refers to the quantity of energy that is absorbed by an object or person where the energy is deposited by ionizing radiation as it passes through materials or the body. The units, radiation absorbed dose (rad) and gray (Gy), measure absorbed dose.1

In 1953, the International Commission on Radiation Units and Measurements (ICRU) adopted the unit rad at the Seventh International Congress of Radiology. This was the unit that replaced the rep, roentgen equivalent physical (detailed later in this blog). Although many believe that the rad is an abbreviation of “radiation absorbed dose”, the ICRU never identified it as such. This suggests that the term “rad” was as a standalone word to be a unit for absorbed dose. There was no documented discussion regarding the use of the rad prior to the Seventh International Congress of Radiology. The closest discussion was during the meeting in 1951 when they determined the need for this type of unit. In 1975, the gray (Gy) replaced the rad as the SI unit of absorbed dose where 1 Gy = 100 rad.10

Louis Harold Gray was a 20th century English physicist who worked mainly on the effects of radiation on biological systems. He was one of the earliest contributors to the field of radiobiology. He worked as a hospital physicist at Mount Vernon Hospital in London and developed the Bragg–Gray equation in collaboration with the father and son team of William Henry Bragg and William Lawrence Bragg. Bragg-Gray theory is the basis for the cavity ionization method of measuring energy absorption by materials exposed to ionizing radiation. Gray’s contributions to radiobiology were numerous. Amongst many other achievements, he developed the concept of RBE (Relative Biological Effectiveness) of doses of neutrons and initiated research into cells in hypoxic tumors and hyperbaric oxygen.11 Gray defined a unit of radiation dosage (absorbed dose) which was later named after him as an SI unit, the gray.

Dose equivalent, also known as effective dose, is a measurement that combines the amount of radiation absorbed and the impact it has on the human body. When it comes to beta and gamma radiation, the dose equivalent is equal to the absorbed dose. However, for alpha and neutron radiation, the dose equivalent surpasses the absorbed dose because these types of radiation have a greater biological impact resulting from their increased ability to damage tissue. To quantify dose equivalent, we use the units of roentgen equivalent man (rem) and sievert (Sv).1

Roentgen equivalent man, or “rem”, was first proposed for use in 1945, but under a different abbreviation. The roentgen was the only unit capable of expressing a radiation exposure at the time. However, it fell short being specifically measurable for photons. Workers came into contact with many other forms of radiation such as alpha particles, beta particles, and neutrons, so Herbert Parker, British-American physicist, created units that would be able to gauge exposures to many types of radiation. These were the roentgen equivalent physical (rep) and the roentgen equivalent biological (reb). Due to similarity in pronunciation between rep and reb, reb was eventually renamed to roentgen equivalent man or mammal (rem) to avoid confusion.

The first appearances of the rem unit in scientific literature were not until 1950.10 The rem related to the rad by multiplying the latter by a quality factor (QF) used to account for the varying biological effects of the different types of radiation. The rad in turn may be obtained from the roentgen by multiplying a dose conversion factor. In air, the dose conversion factor relationship between rad and roentgen is 1 R = 0.88 rad. The absorbed dose to a material is in turn found by multiplying 0.88 by the ratio of the mass energy absorption of the material to that of air.12

Rolf Maximilian Sievert was a Swedish medical physicist. He is best known for his work on the biological effects of ionizing radiation and his pioneering role in the measurement of doses of radiation, especially in its use in the diagnosis and treatment of cancer.13 Sievert contributed significantly to medical physics, earning him the title of “Father of Radiation Protection”. The sievert (Sv), the SI unit representing the stochastic health risk of ionizing radiation, is named after him. The sievert officially replaced the rem as the international SI unit in 1979 with 1 Sv = 100 rem.14

Conclusion

In summary, the history of radiation units is a journey that reflects the progress in our understanding of radiation’s properties and its impact on living organisms. The development of these units has enabled safer and more accurate measurement and assessment of radiation exposure and its effects on human health. By understanding the intricate relationship between radiation and our bodies, we can now take proactive measures to mitigate its harmful effects and promote a safer environment for all.

Sources

  1. NRC: Measuring Radiation. Nrc.gov. Published 2017. https://www.nrc.gov/about-nrc/radiation/health-effects/measuring-radiation.html
  2. The Nobel Prize. The Nobel Prize in Physics 1903. NobelPrize.org. Published 2019. https://www.nobelprize.org/prizes/physics/1903/becquerel/biographical/
  3. Curie – Unit of Radioactivity | nuclear-power.com. Nuclear Power. https://www.nuclear-power.com/nuclear-engineering/radiation-protection/units-of-radioactivity/curie-unit-of-radioactivity/
  4. ‌ Bell DJ. Becquerel (SI unit) | Radiology Reference Article | Radiopaedia.org. Radiopaedia. https://radiopaedia.org/articles/becquerel-si-unit
  5. ‌ Bashir U. Roentgen (unit) | Radiology Reference Article | Radiopaedia.org. Radiopaedia. Accessed August 29, 2023. https://radiopaedia.org/articles/roentgen-unit?lang=us
  6. ‌ Roentgen – Unit of Exposure | nuclear-power.com. Nuclear Power. Accessed August 29, 2023. https://www.nuclear-power.com/nuclear-engineering/radiation-protection/radiation-exposure/roentgen-unit-of-exposure/
  7. ‌ Roentgen (unit) explained. everything.explained.today. Accessed August 29, 2023. http://everything.explained.today/Roentgen_(unit)/
  8. ‌ Bell DJ. Coulomb per kilogram | Radiology Reference Article | Radiopaedia.org. Radiopaedia. Accessed August 29, 2023. https://radiopaedia.org/articles/coulomb-per-kilogram
  9. ‌ Laboratory NHMF. Charles-Augustin de Coulomb – Magnet Academy. nationalmaglab.org. https://nationalmaglab.org/magnet-academy/history-of-electricity-magnetism/pioneers/charles-augustin-de-coulomb/
  10. ‌ Why Did They Call It That? The Origin of Selected Radiological and Nuclear Terms. Museum of Radiation and Radioactivity. Accessed August 29, 2023. https://orau.org/health-physics-museum/articles/selected-radiological-nuclear-terms.html#rad
  11. ‌ LH Gray Memorial Trust: About L.H. Gray. www.lhgraytrust.org. Accessed August 29, 2023. http://www.lhgraytrust.org/lhgraybiography.html
  12. ‌Dosimetric Quantities and Units. U.S. NRC. Published October 25, 2010. Accessed September 11, 2023. https://www.nrc.gov/docs/ML1122/ML11229A688.pdf
  13. Aip.org. Published 2023. Accessed August 29, 2023. https://pubs.aip.org/physicstoday/Online/8433/Rolf-Sievert
  14. ‌ Bell DJ. Sievert (SI unit) | Radiology Reference Article | Radiopaedia.org. Radiopaedia. https://radiopaedia.org/articles/sievert-si-unit?lang=us
05 Jan 2023
2023 Happy New Year Banner with blue gradient background
Medical Physics, Odyssey Software, Personnel Dosimetry, Radiation Safety, Radiation Therapy, Uncategorized Versant Physics 0 comment

A Year in Review & New Resolutions

Coming full circle to another new year invigorates millions. It is a time to reflect and develop goals for a better self, career, or quality of life. Versant Medical Physics & Radiation Safety also looks eagerly into 2023 and new opportunities of growth. We strive to provide our services to continuously benefit existing or future clients—even while appreciating our building-block actions of 2022. Even as our teams replace calendars in the office and spread poor puns about not seeing each other since last year, we shape our goals to provide exceptional support for healthcare providers to ensure safe workplaces and practices:

Remaining at the Forefront of Medical Physics and Radiation Safety

Sometimes the best resolution is to maintain healthy habits achieved from the year before. Versant Physics will continue its focus on sustaining its status as a trusted, knowledgeable business. Our consulting services demonstrate excellence within medical physics and radiation safety and will continue to in 2023. This involves keeping up with new discoveries in science, seeking value-add opportunities, and ensuring our provided support is top quality. It is with this idea that we strive to keep our competitive edge in all aspects.

Maintaining an edge means aligning ourselves with strong sources when the chances arise. In the past year, Versant acquired Radiological Physics Services, Inc (RPS) and completed a business merger with Grove Physics, Inc. We were excited to welcome Joseph Mahoney from Grove Physics as the new Vice President of Diagnostic Physics. Additionally, Versant brought in the talents of Ray Carlson and his team within RPS. The overall consolidation of these companies’ resources with Versant’s has increased services towards our clients. We are enthusiastic about efficiently using these combined assets to their full potential in 2023.

Another constituent to higher performance levels becoming achievable in the new year is that Versant Medical Physics achieved their ISO/IEC 27001:2013 certification in 2022. This certification demonstrates our dedication to being a trusted source. Not only can we be sought for our expertise in the field, but now to maintain personal information and customer data through even better safeguards in 2023. Being certified for strict security and compliance standards allows for peace of mind to clients using our Odyssey software; the protection of which is performed by our own security management team.

Versant Medical Physics and Radiation Safety ISO/IEC 27001:2013 Certification

As a web-based, modern management system, Odyssey’s enhanced security is not its only feature that is being refined. Odyssey is kept as a radiation software suite that our clients can trust for the central administration of radiation safety programs. This is accomplished by our development team’s dedication to the software’s continuous improvement based off internal and external feedback. Radiation safety programs can quickly become complex and difficult to manage for healthcare companies, large or small. In addition to Versant’s experienced personnel, Odyssey provides clients an all-in-one platform to manage their program more easily and effectively. Within 2023, Versant’s development team will be focusing on projects to publish customizable reports. They will also revamp the centralized audit logging in Odyssey as part of software enhancement requests received through the feedback system.  

Radiation Safety Implementation and Maintenance

Radiation safety has an extensive list of requirements and regulations set through organizations such as the NRC. The necessity of radiation safety programs is unquestionable when working with radioactive substances or ionizing radiation generating equipment. However, the issue remains that implementation and maintenance of these programs can become complicated fast. In 2023, Versant Medical Physics will assist healthcare providers simplify program compliance, protecting their employees and overall business.

Versant provides a variety of services, from dosimetry management to the support of our physicists, Radiation Safety Officers, and specialists. These professionals’ collective years of experience range over key modalities of radiation safety:

  • Any company—regardless of size—can run their badge program through our dosimetry monitoring services. Doing so assures access to our competent technical support team that can accommodate any company’s needs. Dosimetry badge management is top priority for this team to make your program easier to handle. The support team provides technical and customer service to your employees, so they understand best practices for the dosimeters they wear and to simplify compliance. This lets your employees quickly get back to what they do best: providing healthcare to those who need it.
  • Versant Medical Physics has board-certified physicists that cover regulatory and diagnostic services across the board. Versant’s physicists are driven to provide top-tier assistance so that our clients meet regulatory guidelines and ALARA fundamentals easily to protect people: employees, patients, and the general population. We will continue to achieve this in 2023 through provision of full-service support for your company’s radiation safety program’s crucial areas. These services can include but are not limited to equipment testing, radiation shielding and design, and comprehensive audits.

Medical Physics and Radiation Safety Certification and Training Support

Another component of medical physics and radiation safety is requirement (depending on role) of being certified for one’s work. Certifications in this field surround topics such as radioactive material handling in a continually evolving medical field. Our online continuing education training courses are available at any time to earn certifications approved by CAMPEP, AAHP, and ASRT. Many professionals within the medical physics and radiation safety fields need continuing education credits; this can be for compliance purposes or to take on new responsibilities within their company. In addition to providing support for our clients, Versant provides certified courses such as

  • Medical Radiation Safety Officer (MRSO) Training – Compliance knowledge and lectures provided to learn day-to-day requirements for a new Medical RSO. This course has been complimented for its clarity and precision of material.
  • Medical X-Ray Radiation Safety Training – Designed for anyone managing a radiation safety program or working with radiative machines in a medical environment. This course is practical and informative to prepare for any inspection.
  • Fluoroscopy Courses – Safety training that details optimization of fluoroscopy techniques while maintaining ALARA practices. This course has been recognized by previous customers for being comprehensive with employable practices.
  • Department of Transportation (DOT) Training – A combination of safety training for radioactive material transport and general handling. Usable for anyone within the shipping process such as technologists.

Our board-certified physicists are available through online communication to assist with questions or understanding of the content. This ensures that students feel supported through the process. By the end, each student can walk away with an accredited certification for the betterment of their career. Versant Medical Physics will ensure this content reaches as many people as possible to deepen their knowledge base in 2023.

Connecting and Sharing Ideas

Over the last decades, social media became an increasingly significant channel of communication for businesses. As a platform to promote their services and generate brand, companies connect in fashions more popular with the public. Although Versant has seen increases in our reach through social media followings and to the visitors of our website, there are still opportunities to further connect with our fellow companies, clients, and acquaintances within the medical physics and radiation safety fields.

In 2023, Versant Physics will bring a stronger focus into revitalizing our most popular channels for engaging content: our blog and podcast. Versant’s blog is a space for informational posts about radiation in the world and its various practices/safe handling in healthcare, as well as general tutorials on our Odyssey software. With the VersantCast Podcast, hosted by our very own medical physicist, Dr. Eric Ramsay, we take our listeners through various topics surrounding radiation, physics, and healthcare with the expansive knowledge of special guests. We are excited to work back into periodic postings and create subject matter that informs, inspires, and educates both readers and listeners alike.

Versant will also strive to further our network through our most popular social media platforms, being LinkedIn, Facebook, and Twitter. Even as a small company in a niche field, social media gives us the opportunity to connect with other people and businesses within the medical physics and radiation safety industry. Creating spaces to share ideas and new discoveries in science are beneficial to us as well as our followers to further our security in the knowledge surrounding the many fields that handle radiation. To join Versant in our goal to be more connected within the industry, you can follow us on LinkedIn, Facebook, and Twitter.

A Leadership Team that Inspires

Our devoted leadership team’s optimistic goals have shaped the future of Versant Medical Physics since 2016 to bring today’s success. Closing out our list of resolutions, our members of leadership provided what they strive to see to fruition in 2023:

Marcie Ramsay – President, CEO

“As president, I hope to continue providing a positive and supportive workplace environment for our professionals. The new year will also bring the opportunity for me to encourage our team to explore new areas of personal interest and work-life balance through Versant Physics’ recent subscription to the online education platform, MasterClass. On a personal note, I intend to devote more time to daily meditation and reflection.”  

Eric Ramsay – Vice President, Commissioning

“Techniques for treatment in Radiation Therapy get more complex each year. Keeping up one’s knowledge base and gaining expertise in new modalities is challenging with a busy schedule. So, a suitable (and frankly, essential) resolution for the new year will be to focus on continuing education and professional development. This involves staying up to date with the latest research and techniques in the field, attending conferences and workshops, as well as seeking out opportunities for collaboration and networking with other professionals including the staff physicists at Versant. This resolution also includes taking steps to maintain a healthy work-life balance as burn out doesn’t help anyone.”

Ben Ramsay – Vice President, Technology & Finance

“Continue to develop a security mindset. With the increase in cyberattacks globally, and the risks internal and external to Versant, establishing a security-focused mindset is one of our goals in line with our ISO 27001 certification. I will also be focusing on improvement of Odyssey usability for existing clients and ways to bundle the software into our services with non-Odyssey customers that will provide enhanced value. Lastly, Versant will benefit from focuses on cross training staff in 2023 so that we are more flexible and capable of maintaining the highest levels of service possible.”

Joseph Mahoney – Vice President, Diagnostic Physics

“In 2023, I will be aiming for improved frequency and clarity of our client communication. Staying up to date and responsive towards the ever-changing regulatory environment will also allow for a strong start into the new year. Aligning with Versant’s desire for our teams to maintain work-life balances, there will be a strong focus in optimization of physical presence for our staff of physicists in geographic regions only where they are most needed so that they all can get back home more often.”  

Cheers to a productive and exciting 2023!

24 Aug 2022
Dosimeter wearers standing and smiling
Dosimetry, Instadose+, Personnel Dosimetry, Radiation Safety, Radiation Safety Officer Versant Physics 0 comment

The 3 Best Personnel Dosimeters: Which Should You Choose?

Continual advances in medicine and medical technology have introduced a greater risk of exposure to ionizing radiation for occupational workers. This has increased the need for effective radiation monitoring services which are a key component of a compliant, well-run radiation safety program.

The problem for most new radiation safety officers is the sheer number of dosimeter types to choose from. How do you know which is the best personnel dosimeter for your radiation safety program? When should you consider phasing out your program’s existing dosimeters for something new?

To help you make your decision, we’ve put together this expert guide on the 3 best personnel dosimeters, their applications, and general specifications.

Instadose+ Wireless Dosimeter

The Instadose+ dosimeter badge is one of the best ways to effectively track cumulative dose for high-risk employees.

Instadose+ Dosimeter

These revolutionary electronic dosimeters utilize Bluetooth technology, Direct Ion Storage (DIS), and SmartMonitoring to wirelessly and remotely transmit on-demand dose data. Mobile devices, such as a smartphone or tablets, as well as PCs or hotspot stations, are used to transmit and record the readings to the wearer’s private account.

The Instadose+ is the best personnel dosimeter for occupational workers like:  

  • Healthcare workers
  • Nuclear medicine professionals
  • Chiropractors
  • Veterinarians
  • Power plant employees
  • Military personnel
  • Flight attendants
  • Lab assistants

Instadose+ badges have a useful dose range of 1 mrem – 500 rem (0.01 mSv – 5 Sv) and a minimum reportable dose of 3 mrem (0.03 mSv).

Energy response:

  • Photon 5 keV – 6 keV

Instadose+ badges are ideal for occupational workers who want access to their own data at the drop of a hat.  The digital read-outs are recorded on a regular basis in accordance with the needs of the radiation safety program. This means no off-site processing.

TLD/OSL Dosimeters

The Genesis Ultra TLD-BP is a lightweight, eco-friendly, thermoluminescent dosimeter. It consists of two parts: a sealed blister pack, which protects the TLD’s internal components, and a separate holder with a clip for attaching to the collar or waist. The TLD also comes with a unique serial number that makes reassigning and tracking an individual’s occupational dose easier.

This personal dosimeter is useful for occupational workers with potential exposure to gamma, beta, neutron, or X-ray radiation. It can be used in a wide range of applications, including:

  • Nuclear medicine facilities
  • Medical imaging centers
  • Diagnostic research facilities
  • Hospitals
  • Universities
  • Nuclear power plants
  • Industrial facilities

The Genesis Ultra TLD-BP has a minimum reportable dose of 1 mrem (0.01 mSv) and a useful dose range of 1 mrem – 1000 rad (0.01 mSv – 10 Gy).

Energy response:

  • Photon 5 keV – 6MeV
  • Beta 0.251 MeV – 5 MeV
  • Neutron (TLD): Thermal – 6 MeV

Unlike with the Instadose+ dosimeter, TLDs require off-site processing to obtain the dose information. This process requires an in-house staff person to collect the dosimeters from wearers, send them out for processing, and re-assign new badges on a regular basis.

Ring Dosimeters

Mirion’s durable extremity dosimeters, commonly referred to as ring dosimeters, are the best personnel dosimeter choice for individuals who perform interventional radiographic procedures or who regularly handle radioisotopes.

There are several different options to choose from, including:

These are ideal for measuring low or high energy beta, gamma, or X-ray radiation to the hands and fingers. These dosimeters pair well with the Instadose+, which measures radiation exposure to the whole body, particularly in research and surgical environments.

Depending on the ring badge, the wear period can last from one week up to six months. They also are comfortable to wear under surgical gloves.

So, Which Is the Right Dosimeter for Your Radiation Safety Program?

When choosing a dosimeter for your radiation safety program, we recommend considering the following:  

  • Functionality and scope of use. How will it be worn and by whom?

  • The information you need the dosimeter to record. Do you need to track full body dose, or the dose received to the extremities, like the hands and fingers?
  • Quality. A higher quality better made dosimeter might cost more up front, but it will withstand continual use and record accurate radiation dose.  
  • Processing Requirements. Do you have the administrative support to collect badges from employees, send them out for processing, and redistribute new badges on a regular basis? If not, you may require a digital dosimeter like the Instadose+ that does not require processing.

If you’re still unsure, you can reach out to our physicists for a personal consultation about the best personnel dosimeter for your program.

Personnel Dosimetry Management with Versant Physics

Here at Versant Physics, we are passionate about radiation safety, adhering to ALARA principles, and helping radiation workers feel confident their dose measurements are accurate.

Our team of experienced physicists and technical support specialists will work with you one-on-one to ensure every aspect of your badge program runs smoothly and efficiently. 

With Versant managing your badge program, you can expect:  

  • Unparalleled customer service and technical support. We take care of everything from the initialization of badges for new wearers to badge troubleshooting.

  • Quality badge administration. Our team manages high-dose reports, adding and removing wearers from the program, and communicates consistently with your RSO.

  • Effective compliance administration. Our effective badge management processes are proven to improve compliance, from read day reminders to comprehensive monthly reports.

Schedule a consultation with our dosimetry program management specialists to get started!

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