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National Research Council (US) and Institute of Medicine (US) Committee on State of the Science of Nuclear Medicine. Advancing Nuclear Medicine Through Innovation. Washington (DC): National Academies Press (US); 2007.

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Advancing Nuclear Medicine Through Innovation.

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8Education and Training of Nuclear Medicine Personnel

This chapter addresses part of the fourth charge of the statement of task that requests that the committee examine the “impact of shortages of highly trained radiopharmaceutical chemists and other nuclear medicine scientists on nuclear medicine basic and translational research, drug discovery, patient care, and short- and long-term strategies to alleviate these shortages if they exist.”

The chapter is organized into the following sections:


The renaissance of nuclear medicine brought about by the promise of using molecular targets as more precise determinants of disease has created new and greater demands for those providing the basic science expertise for the discipline. Creation of new agents will require interdisciplinary teams of molecular, cellular, and structural biologists, bioinformatics specialists, and synthetic and radiopharmaceutical chemists. Improved instrumentation of combined-modality imaging for humans and animals will rely on highly specialized medical physicists and engineers. The maintenance of contemporary, cyclotron-based research and clinical facilities will require additional radiochemists, radiopharmacists, and physicists, whether located in academic medical centers, government laboratories, or pharmaceutical and biotechnology companies. Add to this list the need for appropriate research training for clinician-scientists, and the future demands for education and training will be extensive.

Moreover, the current exacting needs of research, and to some extent of clinical practice, require a degree of super-specialization on the part of the nuclear medicine community previously unrealized. As examples of this specialization, determining how to target specific receptors in the brain, understanding how mutated forms of protein kinases1 are involved in cancer, and understanding how to use gene replacement to repair the ailing heart will necessitate a deeper understanding of the biology of disease and its molecular manifestations than ever before. Thus, there are qualitative questions about training candidates for careers in nuclear medicine research as well as quantitative ones that relate to the need for additional specialists.

Because of the multidisciplinary nature of nuclear medicine research and clinical practice, the committee undertook a broad look at the required personnel, from research technologists to clinician-scientists. The committee conducted an extensive search for specific data (e.g., number of faculty positions available, number of positions available in industry, the time it takes to fill each position); however, the committee was unable to find any systematic survey that gave reliable data. To gain a better understanding of the challenges, the committee solicited input from relevant scientific societies, government agencies, and industry representatives. In addition to the comments from scientific societies and government agencies and industry, selected members of training programs for chemists, radiopharmacists, medical physicists, health physicists, and clinician-scientists were invited to a panel discussion at the committee’s third meeting (Appendix A) which was dedicated to training needs. The following sections discuss the current status of the workforce by occupation.


The National Electrical Manufacturers Association (NEMA), which represents more than 90 percent of the market for nuclear medicine imaging equipment, “is convinced of the need for larger numbers of practitioners trained in the technical acquisition, pharmaceutical manufacture, and clinical interpretation of images in nuclear medicine. This will include physicists, radiopharmacists, and clinician readers” (Richard Eaton, NEMA, personal communication). This statement is supported by a recent report that surveyed the need for nuclear medicine scientists (Center for Health Workforce Studies 2006). Based on this survey, 86 percent of 310 respon dents in the fields of chemistry, pharmacy, physics, computer science and engineering, and other disciplines stated that very few qualified candidates were available.

8.2.1. Chemists

One of the most enriching aspects of radiopharmaceutical research is that it is generally carried out in an interdisciplinary environment where chemists work together with physicians, physicists, and biologists, sharing the excitement of solving important problems in medicine. Chemists who work in this discipline are often attracted by the opportunity to integrate chemistry with other imaging sciences, such as instrumentation. For example, the development of a new generation of small-animal imaging and multimodality imaging instruments created new challenges for the radiopharmaceutical chemist to produce radiopharmaceuticals with the very high specific activity necessary to conduct tracer studies in small animals.

Chemists who work in the field of nuclear medicine are trained in radiotracer techniques through a variety of mechanisms. Although formal radiochemistry graduate programs exist in the United States, the number has been declining because of lack of adequate funding, and there are few radiochemistry graduate programs. It is estimated that only 5 to 10 new doctoral degrees in radiochemistry are granted each year (Greg Choppin, Florida State University, personal communication). Most radiopharmaceutical chemists in the field are recruited from graduate and postgraduate university programs in organic, inorganic, medicinal, and analytical chemistry and add radiochemical skills through their postdoctoral experience. Some doctoral dissertations are written for work performed in nuclear medicine research laboratories where the principal radiopharmaceutical chemist holds an auxiliary or adjunct appointment in chemistry, nuclear/biomedical engineering, or another related field. As a result, there are few formal courses in radiochemical and radiopharmaceutical theory and practice. Moreover many if not most radiochemists are relatively specialized, concentrating on fluorine, other halogen, or technetium chemistry.

Another mechanism by which chemists from other disciplines obtain their training in radiolabeling techniques is through continuing education courses conducted by universities, scientific societies (e.g., American Chemical Society, Society of Radiopharmaceutical Sciences), the national laboratories, other Department of Energy (DOE) entities, the National Institutes of Health (NIH), or industrial training programs. Many also receive additional training on the job in the research environment. These efforts, however, lack the required depth, and these training pathways are insufficient to meet the needs of the anticipated advanced technologies that will become available in the future.

In April 2002, the DOE Office of Biological and Environmental Research held a workshop on Radiochemistry Research Resources (DOE 2002). Attending the workshop were representatives from radiopharmaceutical chemistry training programs at universities, DOE’s national laboratories, and NIH. The conclusion of the workshop was that “the current shortage of radiochemist applicants was evident” and that “at their institutions there were openings currently for postdoctoral students, junior faculty members, and senior faculty members.” The assembled group of experts felt that a more extensive nationwide survey was necessary. Subsequent to that workshop, data were solicited from pharmaceutical and biotech companies as well as 30 other organizations with interest in nuclear medicine. The data confirmed a serious deficiency of radiochemistry personnel possessing the skills that will be needed for future technologies in the United States (DOE 2002).

Subsequent reviews of this field by other organizations have also come to the same conclusions. The National Research Council study that reviewed the health of the U.S. chemical research community reported that although the United States still leads chemical research worldwide, its dominance in radiochemistry is being challenged (NRC 2007). Furthermore, a recent American Chemical Society symposium2 noted the increased need for chemists with expertise in nuclear medicine with a growing requirement for chemists with additional training in radiochemistry. Similarly, a subcommittee of the DOE Biological and Environmental Research Advisory Committee (DOE 2004) noted an acute need for additional “trained chemists (including pharmaceutical chemists, organic chemists, inorganic chemists, and peptide and protein chemists) with an interest and ability in the design and synthesis of molecular imaging and targeted probes.” On the basis of a survey of 20 institutions, that subcommittee reported that on average, two to three positions per institution went unfilled because of a lack of qualified applicants. The International Atomic Energy Agency (IAEA) has conducted a worldwide study of radiochemistry personnel and determined that only India and China have sufficient numbers to meet current and future needs (IAEA 2002).

The committee’s own review concurs that one of the continuing challenges is to recruit new chemists. Feedback and discussions with all of our constituents revealed concerns about the lack of radiochemistry personnel at academic institutions and in industry. Industry representatives stated that there is a need for organic and medicinal chemists with strong backgrounds in radiochemistry to provide the expertise needed for drug discovery and development (personal communication, William Clarke, GE Healthcare).

8.2.2. Radiopharmacists

Closely associated with the shortage of radiochemists is the rapidly growing need for more radiopharmacists. Currently there are several ways in which pharmacists become involved in the field of nuclear medicine. They can complete advanced degrees (Ph.D. or M.S.) in radiopharmacy, take advanced courses in nuclear pharmacy following their completion of pharmacy school, or simply take the necessary training to become a Nuclear Regulatory Commission (U.S. NRC) “authorized user.”3 The Board of Pharmaceutical Specialties also provides a nuclear pharmacy specialty certification. According to the Society of Nuclear Medicine, 468 pharmacists held such certification in the United States in 2003.

With a new emphasis on research in molecular imaging at academic medical centers, the increasing expansion of commercial radiopharmaceutical companies supplying hospitals with unit doses, and the rapid expansion in commercial positron emission tomography (PET) facilities, there is considerable demand for individuals with radiopharmacy training and experience. Industry is acutely aware of this shortage since they are having difficulty filling the job openings as nuclear medicine becomes more vital in patient care. NEMA reports that there are approximately 350 commercial nuclear pharmacies in the United States with another 50 opening over the next 5 years. These pharmacies will generate the need for an additional 150 nuclear pharmacists. Industry alone will need a steady supply of approximately 200 nuclear pharmacists per year.

Currently the majority of nuclear pharmacists has received only the necessary training to become an “authorized user,” which consist of 700 hours of didactic instruction in basics of radiation methods and protection. This training is most commonly obtained as part of a doctor of pharmacy degree or as a nondegree “authorized user” postgraduate course. Continuing education courses are also conducted by universities and scientific societies for pharmacists to become “authorized users.”

Radiopharmacists needed to provide the necessary faculty and individuals capable of leading the research efforts required to advance the field of nuclear medicine are educated primarily in university schools of pharmacy. They receive a bachelor’s degree in pharmacy and then complete additional course work in radiopharmacy or enroll in graduate M.S. or Ph.D. programs specifically in radiopharmacy. There are currently very few such programs (less than a dozen), each with a limited number of trainees. There is a critical need to expand these programs.

8.2.3. Physical Scientists and Engineers

Physicists’ involvement in nuclear medicine is broad and diverse, including the disciplines of medical physics, instrumentation, computer and computational sciences, and health physics. Physicists trained in these disciplines are essential to research conducted at universities and industry, as well as in clinical practice. There are many avenues for the entry of physicists into nuclear medicine. Students with Bachelor of Science degrees or M.S. or Ph.D. degrees in physics or engineering are recruited directly into academic research institutions or industry and gain experience in such areas as imaging techniques and instrumentation, cyclotron targetry and engineering, and data processing. There are also university programs for individuals to obtain M.S. or Ph.D. degrees in subspecialty areas of medical physics, such as medical nuclear physics, diagnostic radiological physics, medical health physics, and therapeutic radiological physics. Currently, eight universities in the United States offer graduate programs in medical physics. The eight universities provide postdoctoral research programs, clinical residencies, and bioengineering programs, and all are accredited by the Commission on Accreditation of Medical Physics Education Program, Inc. (CAMPEP 2007). In addition, there are 46 nonaccredited programs at medical centers throughout the United States. The American Board of Radiology and the American Board of Medical Physicists also offer certification opportunities for medical physicists. Health physicists focus on safety issues of radiation workers and are certified by the American Board of Health Physics.

In recent years, biomedical and nuclear engineering departments, respectively, have emerged as an alternative venue for the training of physical scientists and engineers for careers in nuclear medicine. The breadth of topics covered within biomedical engineering programs currently ranges from algorithm and detector development to applying the tools of molecular biology for the intelligent design of nanotechnology-driven radionuclide carrier systems. Generally, these programs have been most effective when engineering students have the opportunity to interact with medical-school-based scientists and clinicians through participation in multidisciplinary research projects. Similarly, nuclear engineering departments offer a general curriculum that encompasses the fundamentals of nuclear science, radiation measurements, and nuclear and radiation applications in biology and medicine. Some nuclear engineering students elect to participate in research projects related to nuclear medicine, radiochemistry, radiation biology, imaging, computation modeling, or other medical applications.

However, a shortage of physicists and engineers exists in many catego ries: medical physics, instrumentation, computer computational sciences, and health physics. The shortage of physicists can be attributed to the declining number of training programs. For example, 20 years ago 200 to 400 health physicists were being trained each year; today the number is less than 50 (Ken Miller, Pennsylvania State University, personal communication). There are currently eight accredited programs for medical physicists in the United States with approximately 350 students in training (Paul DeLuca, University of Wisconsin, personal communication). Based on the estimated needs calculated by the American Association of Physicists in Medicine (AAPM), this number of trainees is not adequate to sustain the growth that is anticipated for the field (DeLuca 2004). Based on the membership patterns estimated by AAPM, 750 students would be needed to supply 200 new physicists per year.

8.2.4. Clinician-Scientists

There is a considerable need for appropriately trained clinician-scientists to further the development and implementation of nuclear medicine diagnostic and therapeutic tools and to act as mentors for a much needed increase in trainees. The need for an increase in the number of such individuals is a result of a belief that nuclear medicine imaging mechanisms can uniquely provide clinically relevant insights into many molecular manifestations of disease. With a rapid increase in the number of cyclotrons and radiopharmacy units proximate to PET scanners, the development of new potentially useful nuclear probes of disease will multiply. The large number of new probes to be tested for their suitability on volunteers and patients will require additional research physicians from many disciplines, including nuclear medicine specialists, radiologists, cardiologists, oncologists, and neurologists. Many will need additional training in nuclear medicine and molecular imaging techniques in order to conduct the required clinical trials. Similarly, a substantial increase in the number of new radiolabeled metabolic therapies will require clinician-scientists able to investigate their utility.

The majority of specialists who perform diagnostic nuclear medicine procedures have completed residencies in nuclear medicine approved by the Accreditation Council for Graduate Medical Education. They receive certification through the American Board of Nuclear Medicine or through approved residencies in diagnostic radiology and certification by the American Board of Radiology, sometimes also with Special Competency certification in nuclear medicine. Many board-certified radiologists who have not obtained Special Competency certification in nuclear medicine are involved in the interpretation of nuclear medicine studies, as are a number of other clinical specialists such as cardiologists and neurologists. In the case of cardiologists and neurologists, specialty professional societies and their respective certifying boards have created mechanisms whereby their member physicians do not necessarily have to complete a diagnostic radiology or nuclear medicine residency to perform and interpret nuclear medicine procedures. For example, guidelines for training in cardiovascular nuclear medicine (nuclear cardiology) have been established by the American Society of Nuclear Cardiology and the American College of Cardiology. They are part of the overall training guidelines in adult cardiovascular medicine as accepted by consensus from the Core Cardiology Training Symposium in 1994. These training guidelines have been updated to include emerging imaging technologies, such as single photon emission computed tomography/ computed tomography (SPECT/CT) and PET/CT hybrid modality imaging systems, and are part of the general 3-year training in cardiovascular medicine.

Training requirements and curricula may therefore vary widely among these groups of imagers. Regarding use of unsealed sources of radioactivity, practitioners require certification by the American Board of Nuclear Medicine, the American Board of Radiology with Special Competency in Nuclear Medicine, or Radiation Oncology. In addition, the practitioner must be an authorized user and meet applicable U.S. NRC and/or Agreement State4 requirements

The training of physicians involved in research and the clinical practice of nuclear medicine will require substantial changes with the evolution of the field. One broad division within nuclear medicine can be found between nuclear medicine physicians who are predominantly involved in diagnostic imaging and those involved in targeted radionuclide therapy. However, even within diagnostic imaging, nuclear medicine has changed considerably with the advent of combined-modality imaging. Clearly, a full interpretation of an integrated PET/CT or SPECT/CT scan requires cross-training of nuclear medical specialists in radiology. There are currently few nuclear medicine physicians or radiologists competent in fully interpreting images taken with combined modality machines. For the relatively few who are competent to do so, private practice may be so intellectually and financially rewarding that additional incentives will be needed to recruit physicians to conduct clinical research.

At present, research and clinical nuclear medicine is concentrated mainly on oncology, heart disease, and neurological disorders. Although the former two are firmly established in clinical practice, most novel neurological applications of nuclear medicine have not been translated into the clinic. This, however, will change with an increased development of new PET tracers useful for the diagnosis and management of dementias and other neurodegenerative diseases as well as movement disorders.

Given this background, creation of a molecular imaging residency or fellowship, where individuals can assimilate the latest technologies into clinical practice is challenging. There is little consensus on curriculum or the topics to be covered and the complement of faculty expertise needed to teach these topics. Irrespective of these challenges, the training of nuclear medicine clinician-scientists will be different within the next 5 to10 years, and preparations must be made now in order to have an appropriate number of individuals capable of translating the latest technological innovations into clinical practice.

Without an organized effort to define the skills needed to guide clinical development of these new technologies, the field will not realize its potential. Traditional nuclear medicine, radiology, cardiology, neurology, and other specialty programs are currently not training a sufficient number of multidisciplinary imaging specialists to accomplish the desired outcome. Trainees today are not being given proper incentives to pursue an academic research career or to lead clinical trials because clinical departments preferentially reward clinical work over research.

Government agencies and the private sector must also refocus their efforts to support training programs that will generate more clinician-scientists. Imaging departments and divisions need to emphasize the importance of encouraging and supporting clinician-scientists as key participants in the process of delivering state-of-the-art health care and in advancing the area of personalized medicine. The next “PET” instrument or the next “FDG” radiotracer will not be developed unless capable clinician-scientists who understand how to conduct clinical trials are in place to translate laboratory discovery into clinical practice. Clinical trials led by experienced nuclear medicine and imaging science experts will provide young clinician-scientists with the opportunity to learn the process of conducting such trials.


Cardiologists share in the clinical utilization of nuclear medicine. According to industry estimates, the number of cardiac nuclear medicine procedures performed each year in the United States exceeds 7 million (about a third of all nuclear medicine procedures) (Heinz Schelbert, University of California at Los Angeles, personal communications). These procedures contribute substantially to the detection of cardiovascular disease, to the assessment of risk for cardiac mortality and morbidity, and to the stratification of cardiac patients for optimum treatment. A substantial fraction of them are performed by cardiologists alone or in collaboration with nuclear medicine physicians or radiologists. Nuclear cardiologists together with nuclear medicine physicians account for most of the ongoing clinical research activities in cardiovascular nuclear medicine; these activities rely mostly on well-established nuclear imaging techniques

Research and development of novel radionuclide-based approaches for delineating and quantifying local molecular and cellular processes in the human cardiovascular system is urgently needed so that these new approaches can be transferred into the clinic. Yet, because of a serious shortage of qualified clinician-scientists, this area of research with its potentially considerable impact on patient care has remained underdeveloped. What is needed to overcome this impairment are nuclear medicine specialists who are well trained in basic and clinical cardiovascular sciences and research methodologies. Formal training of such individuals does not yet exist.


In general, medical and surgical oncologists need no special training in imaging and are satisfied to accept the interpretation of imaging studies by competent diagnosticians. On the other hand, the use of targeted radionuclide therapy requires considerable cooperation between nuclear medicine and oncology. This is particularly true for therapies given to very ill patients. Antithyroid radioiodine therapy, in most instances, is done with relatively healthy patients and can be readily handled by nuclear physicians and endocrinologists. This is not the case with other radionuclide treatments, where metabolic, targeted radionuclide therapy is added to patients already being burdened with many toxic nonradioactive drugs. A nuclear medicine physician not also trained in clinical oncology cannot handle such patients alone, and close collaboration with clinical oncologists is a prerequisite. Likewise, medical and radiation oncologists often need assistance from nuclear medicine physicians, particularly in understanding results, advantages and limitations of dosimetry, radiation protection, and radiation side effects. There are no formal cross-training programs at present and experience can only be gained by an oncologist spending time in a nuclear medicine department. The matter of proper training for oncologists in the use of radioactive materials is amplified when they are involved in research projects, where the issues of radiation dosimetry, radiation protection, and radiation side effects are considerable.

Clinical Neuroscientists

Thus far, neuronuclear medicine has had a limited impact on clinical decision making. Brain imaging is mainly used for the assessment of patho morphology,5 and functional magnetic resonance imaging (fMRI) is used in evaluating blood flow in both healthy and diseased brains. Although functional brain imaging started with functional PET (fPET) examinations, the radiation exposure from fPET, among other factors, has prompted a shift to the use of fMRI. However, more specific molecular-imaging-based tests using radioactive molecular probes are on the horizon and could change diagnostic imaging practice in dementias, movement disorders, and possibly demyelinating disease.6 It is foreseeable that imaging tests developed in the future will be useful for therapeutic decision making and control of disease. Thus, there will be a greater need for interactions between neurologists, neurosurgeons, neuroradiologists, and properly trained nuclear medicine physicians. Nuclear medicine physicians specializing in brain imaging will need additional skills in the interpretation of morphological imaging examinations, while neurologists, neurosurgeons, and neuroradiologists will need to develop an understanding of tracer imaging probes and tracer kinetics in relation to morphological imaging results.


Skilled technical personnel to conduct nuclear medicine exams are necessary in both the clinical and research settings. Yet, the number of training programs for nuclear medicine technologists had already declined prior to the emergence of PET. With the introduction of PET and PET/CT into clinical practice, the need for well-trained technologists has become even more urgent. Training of nuclear medicine technologists requires 2- or 4-year college-level course work that includes practical experience and leads to a Bachelor of Arts or Associate of Arts degree. National certification of nuclear medicine technologists is conducted by the Nuclear Medicine Technology Certification Board or the American Registry of Radiological Technologists (ARRT 2005). However, much of the earlier staff shortages, especially of technologists with qualification and certification for PET/CT hybrid systems, has now been relieved because colleges began offering 1-year training programs in nuclear medicine technology to individuals with some prior imaging experience. With the likely introduction of PET/MR hybrid systems into clinical care in the near future, the challenge may again be repeated. Some concerns, however, have been expressed by technologists about whether the one-year training pathway adequately covers the technical aspects of nuclear medicine. In nuclear medicine research (unlike clinical nuclear medicine), a substantial shortage of qualified technologists continues to persist. This shortage has been further exacerbated by an increasing reliance on small-animal radiotracer imaging in drug discovery and research in academic medical centers and in the biotechnology and pharmaceutical industry. Industry representatives informed the committee that the number of small-animal imaging facilities in their research has dramatically increased within the past several years without a commensurate increase in the number of trained or qualified individuals. It appears that only a few clinically trained nuclear medicine technologists participate in this area of research activity, likely due to lower financial rewards. Most small-animal imaging facilities therefore are staffed by research assistants, radiopharmacists, physicists, or biomedical engineers.


From the testimony presented as well as the committee’s own observations and experience, the following are considered to be impediments to the realization of an expanded work-force.

  1. Shortage of Nuclear Medicine Personnel. There are shortages of both clinical and research personnel in all nuclear medicine disciplines (chemists, radiopharmacists, physicists, engineers, clinician-scientists, and technologists) with an impending “generation gap” of leadership in the field. Training, particularly of radiopharmaceutical chemists, has not kept up with current demands in universities, medical institutions, and industry, a problem that is exacerbated by a critical shortage of university faculty in nuclear chemistry and radiochemistry (NRC 2007). Nuclear medicine research requires a multidisciplinary team consisting of individuals with extremely varied education and training. Only by training an adequate number of individuals in these various disciplines will nuclear medicine and molecular imaging/therapy reach its potential. There is a pressing need for additional training programs with the proper infrastructure (including a culture of interdisciplinary science), appropriate faculty, and more doctoral students and postdoctoral fellowship opportunities.
  2. Acute Shortage of Chemists. The recruitment of new chemists into the field of nuclear medicine is a significant and continual challenge. Such recruitment has been difficult because many of the chemists working in the nuclear medicine area do not have academic appointments in chemistry departments and therefore do not have access to chemistry graduate students. Thus, it is essential to reach out to chemistry students at the undergraduate and graduate student levels to fill the pipeline and avoid an impending generation gap in leadership in radiopharmaceutical chemistry. Furthermore, with the current decline in the number of U.S. students going into chemistry, the restriction of training grants to U.S. citizens and permanent residents as required by the Public Health Service Act7 is an impediment to recruitment of new talent into the field.


RECOMMENDATION 1: Train nuclear medicine scientists. To address the shortage of nuclear medicine scientists, engineers, and research physicians, the NIH and the DOE, in conjunction with specialty societies, should con sider convening expert panels to identify the most critical national needs for training and determine how best to develop appropriate curricula to train the next generation of scientists and provide for their support.

RECOMMENDATION 2: Provide additional, innovative training grants. To address the needs documented in this report, specialized instruction of chemists from overseas could be accomplished in some innovative fashion (particularly in DOE-supported programs) by linking training to research. This might take the form of subsidies for course development and delivery as well as tuition subventions. By directly linking training to specific re search efforts, such subventions would differ from conventional NIH/DOE training grants.



Kinases are enzymes that transfer phosphate groups to other molecules.


21st Century Radiochemistry Opportunities: A Symposium Highlighting Nuclear Science Workforce Needs, March 2006, (http://oasys2​.confex​.com/acs/231nm/techprogram/).


The U.S. NRC regulates the use of radioactive material in medicine by issuing licenses to medical facilities and users. Research involving human subjects using radioactive materials may only be performed if the licensee has fulfilled the requirements outlined in 10 CFR Part 35. To become an authorized user, the applicant must complete a minimum of 700 hours of training.


Agreement States are those states to which the U.S. NRC has transferred some of its regulatory authority. Transfer of U.S. NRC’s authority to a state is an agreement that is signed by the governor of the state and the chairman of the commission.


Pathomorphology is the study of structural changes in tissues or cells resulting from abnormal conditions.


Demyelinating diseases are any conditions that result in damage to the protective covering (myelin sheath) that surrounds the nerves in the brain and spinal cord.


The Public Health Service Act restricts training awards to U.S. citizens and permanent residents. The law was implemented through the Code of Federal Regulations (http://grants1​​/training/NRSA_NameChangeLegislation​.rtf) (NIH 2002).

Copyright © 2007, National Academy of Sciences.
Bookshelf ID: NBK11463


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