An Assessment of the National Institute of Standards and Technology Physics Laboratory: Fiscal Year 2010 (2010)

The goal of the Ionizing Radiation Division is to provide the foundation of ionizing radiation measurements for the nation through its mission to develop, maintain, and disseminate the national standards for ionizing radiation and radioactivity to meet national needs for health care, the environment, U.S. industry, and homeland security.

The Ionizing Radiation Division, located at NIST’s Gaithersburg, Maryland, campus, has 39 scientists/engineers, 5 technicians, 125 NIST associates, and 4 administrative support staff, as of January 2010. Its FY 2009 budget was about $13.4 million, 43 percent of which was STRS funding.

The major programs in the division include the following:

• Standards and calibrations—The division is a recognized world leader in the area of radiation standards. The importance of this function is currently growing, with increased needs in the medical imaging, therapy, and homeland security areas.

• Neutron physics—The division has a unique program in basic nuclear physics that has several important experiments currently underway and a number of unique studies awaiting execution.

• Medical imaging and therapy—Although this activity has been a focus in the division for a number of years, through the work in mammography and brachytherapy calibrations, it has recently become a wider program with the impending installation of a PET/CT scanner.

The mission of the Radiation Interactions and Dosimetry Group is to develop dosimetric standards for x-rays, gamma rays, and electrons based on the Système International (SI) unit, the gray, for homeland security, medical, radiation processing, and radiation protection applications. These standards are disseminated by means of calibrations and proficiency testing services provided to maintain quality assurance and traceability. The projects in the group are classified in six areas: theoretical dosimetry, quantum metrology, medical dosimetry, homeland security applications, industrial applications, and protection and accident dosimetry. Work on homeland security issues has continued since the previous panel review, in 2008. There has, however, been an

increasing focus on standards, calibrations, and traceability with respect to medical imaging.

Significant progress has been made in a number of the group’s measurement standards and calibration services, including the following:

• Low-energy absolute x-ray calibration wavelength metrology—production of data needed in a number of areas in quantum metrology;

• Maintenance of the national mammography standard—necessary to ensure that the radiation doses delivered in this medical imaging technique are consistent and safe;

• The development of dosimetry systems for industrial applications—necessary to meet the growing need for accurate dosimetry in the radiation sterilization of medical disposables and the treatment of food and other biological materials;

• Prostate seed brachytherapy dosimetry—necessary to ensure that the radiation doses delivered during radiation treatment for certain cancers are accurate in intensity and spatial distribution; and

• The calibration of miniature x-ray sources used for brachytherapy—necessary to establish a national primary air-kerma-rate standard for this developing technique for in situ irradiation of cancerous tissue in humans.

The group regularly compares its standards for radiation dose with those of other national and international standards laboratories, and in most cases they compare to within 0.5 percent with the averaged measurements of these other laboratories. This is an excellent outcome.

Two new projects of major need for the nation with respect to the safety of patients and technicians are calibration and dosimetry for part- and whole-body diagnostic studies and the calibration and ongoing monitoring of external radiation therapy (linear particle accelerators [LINACs] producing beams of x-rays, electrons, and, more recently, protons and heavier charged particles for conventional and conformal delivery systems, and cobalt-60 [Co-60] systems). This undertaking has priority for action commencing immediately. These needs have arisen in a fashion similar to the brachytherapy calibration and mammography work now successfully underway.

Budget and staffing are critical issues for this group, which is experiencing decreases in personnel and funding. Three researchers left the group in February 2010—one retired and two transferred to other groups owing to a lack of funding. This decrease in staff is occurring even as the workload for calibrations is increasing. This attrition should be reversed.

The mission of the Radioactivity Group is to develop, maintain, and disseminate radioactivity standards, develop and apply radioactivity measurement techniques, and engage in research to meet the requirements for new standards. This mission leads to the development, maintenance, and dissemination of the national measurement standards for ionizing radiation and to engagement in research for meeting the requirements for new

standards needed by industry, medicine, and government. Further, it provides standards for the radioactivity based on the SI unit, the becquerel, for homeland security, environmental, medical, and radiation protection applications.

There are a number of good, technically advanced programs in the Radioactivity Group. The following are notable examples. The Low-Level Radiochemistry Program is involved in many research projects dealing with analysis of low levels of radioactivity. These include the investigations of methods for radionuclide speciation in soil, techniques for isolation in the characterization of various radioactive particles in cells and sediments, the development of rapid radioactivity screening methods for emergency situations, including approaches to assess internal contamination by radionuclides that are difficult to measure.

Through the Medical Imaging Standards Program, NIST has taken up the national need for the calibration and standardization of nuclear medicine imaging systems by the acquisition of a PET/CT instrument that will provide the platform for the development of calibration phantoms to be used by manufacturers and clinics for instrument-performance calibrations. An international collaboration program through the International Atomic Energy Agency has been initiated so that both primary institutions and second-world countries can have materials and protocols for instrument-performance assessments and calibrations. This work is encouraged by the panel, and it is important to note that the national needs go beyond phantom creation and calibration standards for PET/CT. Indeed, the current instrumentation being commercially produced requires standardization for the safety and quality of medical diagnostics. These standardization needs include the robustness of attenuation correction, motion compensation, and scatter correction. In addition, this program should include single photon emission tomography and standard multidetector x-ray CT within its charge. SPECT instruments have additional algorithmic components, such as depth-dependent collimator response, truncation compensation, and methods of attenuation compensation. (For clarity, it is noted that NIST is not involved in the development of the instruments themselves or their applications, except to the extent of understanding their operation and applications sufficiently to establish standards.)

The investigators have carried out significant work on the development of standards for radionuclides employed in SPECT positron emission tomography and nuclides used directly for therapy. These studies have resulted in a significant number of publications in appropriate journals. A PET/CT scanner for humans has been ordered to allow the assessment both of the standards developed for PET/CT and of phantoms developed to determine the characteristics of the various PET/CT scanners being utilized. This is an important project, and the group is well qualified to carry out these studies. At present, the group involved in this work consists of three staff members; however, other individuals are being transferred to this program.

The mission of the Neutron Interactions and Dosimetry Group is to maintain and disseminate measurement standards for neutron dosimeters, neutron survey instruments, and neutron sources, and to improve neutron cross-section standards through both evaluation and experimental work. This effort will provide neutron standards and

measurements needed for worker protection, nuclear power, homeland security, and fundamental applications and will provide the world’s most accurate measurements of neutron coherent scattering lengths, important to materials science research and the modeling of the nuclear potentials.

Eight permanent scientific staff, 2 technicians, and approximately 20 visiting scientists with various residence times comprise the personnel involved in neutron innovative physics experiments and the neutron dosimetry and calibration program of NIST. The facility’s major resource is a 20 MW reactor with nine beam lines available for a variety of experiments. The program plans an expansion to extended space and additional beam lines.

This program is responsible for a number of very significant accomplishments. The neutron radiography program relies on the unique characteristics of neutrons to penetrate metals and interact with light elements as well as with structural aspects of the medium (e.g., metal fine structure) so as to allow high-sensitivity detection of water, boron, lithium, and so on as well as regional defects in metals. This program has major projects of national importance. The industrial applications have recently gone beyond the fuel cell evaluation of water distribution to the study of lithium-ion batteries. Resolution is obtainable at 10 micrometers. A new development, first in the world, is neutron phase contrast imaging. The contrast mechanisms leading to good target-to-background images are based on material property changes associated with stressed metals or the carbon/hydrogen composition of biological objects. The images show unprecedented results. Other advances are the production of a polarized helium-3 system that provides a type of filter for polarized neutrons that enables physics experiments not otherwise possible. The NIST technology serves programs both at NIST and at the Oak Ridge National Laboratory. The unique aspect is the preparation of neutron polarizer cells available to a wide range of fundamental physics experimenters.

The service component of the Neutron Interactions and Dosimetry Group includes the best-in-the-world results of calibration using the unique manganese sulfate (MnSO₄) bath as well as the new smaller but portable MnSO₄system. The assessment of their excellence is based on a comparison at an international intercomparison with 10 other facilities. The current and planned calibrations and evaluations of dosimeters using the group’s californium-252 (Cf-252) neutron sources as well as its innovations in a scintillation/lithium dosimeter are significant advances that make this one of the best service centers in the world.

Some of the service projects have been canceled. For example, reactor-materials dosimetry calibrations related to commercial power plants are no longer provided by NIST, and another project was not pursued owing to a lack of personnel. The service component of the neutron group is extremely important to the nation and should be expanded as warranted either by perceived need or by customer requests.

Programs in all three groups in the Ionizing Radiation Division that are of major importance to national security are the performance standards for radiation-detection devices (portal screening and handheld devices) used for the detection of nuclear explosives, and the development of national x-ray standards for security-screening

systems. These projects are essential activities for activities of the Department of Homeland Security’s Domestic Nuclear Detection Office.

Following is the summary of the panel’s assessment of the overall quality of the Ionizing Radiation Division (including opportunities for improvement) in terms of the three criteria as requested by the NIST Director (see Chapter 1).

In general, the programs currently underway in the Ionizing Radiation Division are as good as or better than those in other national and international laboratories. Examples include the neutron radiography and basic physics programs, the development of standards and calibration techniques in which the results obtained generally agree extremely well with those of other laboratories, and calibration programs supporting advanced medical imaging techniques such as PET/CT.

The funding of the Ionizing Radiation Division is not adequate at this time, when the need for its services is increasing. It is the panel’s understanding that, subsequent to its visit to the Ionizing Radiation Division for this assessment, two members of the Radiation Interactions and Dosimetry Group were transferred to other groups for budgetary reasons and the group leader has retired, with his responsibilities being assumed by an existing lead.

The Radiation Interactions and Dosimetry Group’s losses come at a time when the needs for standards and the demand for calibrations are increasing. Moreover, the Neutron Interactions and Dosimetry Group’s loss of two researchers to retirement in the past years comes at a time when new reactor beam lines are being constructed for the specific use of this group. Although attrition is to be expected, there appears to be no plan to replace the losses.

The building in which the majority of the division is housed is old and in need of a major upgrade. With the confirmation of a new chief for the division, an aggressive strategic plan should be put in place by the chief that will ensure the continuation of the high quality of work being done by the division and increase funding for the group.

The Ionizing Radiation Division currently has 48 full-time staff and 125 NIST associates. The high number of associates versus full-time employees is a matter of

concern; the full-time staff should be expanded in the future at the expense of associates. Clearly, there are budgetary issues associated with this recommended change.

The Ionizing Radiation Division is recognized worldwide for its expertise in the measurement of standards related to radiation.

The mission, projects, and performance of the Ionizing Radiation Division are good. The situation with respect to major equipment has improved since the previous panel review, in 2008. Since that review, some older, unreliable equipment has been decommissioned, and other equipment has been moved. These changes have freed up space for the installation of a high-power LINAC needed to do the high-dose calibrations required for industrial processes. In addition, new beam lines for neutron physics are under construction, and a PET/CT scanner has been ordered that will greatly enhance the medical imaging capability. The time required to complete some projects appears to be longer than might be desired, but much of this is due to staff and budget constraints.

Building 245, where most of the Ionizing Radiation Division is housed, is one of the oldest on the NIST campus. During the 2008 panel review, it became very clear that the condition of this building was very poor, as was noted in the panel’s 2008 report. Since that time, the building has seen some improvement, but it still needs a major upgrade.

The following comments pertain to the division’s responses to items raised by the panel that conducted the 2008 review:

• Much of the division’s radiation-producing equipment is obsolete or in poor condition and should be modernized or replaced.—The division has made significant progress in this area since the 2008 review. The decommissioning of old equipment has freed up space for a new high-power LINAC and the installation of a PET/CT scanner. Further, the construction of an extension to the existing experimental hall at the NIST Center for Neutron Research’s (NCNR’s) neutron-producing reactor facility will allow the installation of more experiments in this facility.

• The NCNR experimental hall is being enlarged and the Neutron Interactions Group will be acquiring new beam lines. These new facilities will require new experimental equipment and staff.—Little progress has been made in this regard, but construction at the NCNR has been delayed, so there is no need for the equipment and staff at this time. Purchase of the equipment is budgeted for FY 2010.

• The Neutron Interactions Group should pursue interagency agreements as a means of getting increased funding and manpower for additional neutron experiments.—This suggestion is being vigorously pursued.

• External Advisory Committees should be appointed to help the Radioactivity Group select and prioritize research projects.—There appears to be some resistance to this suggestion, and there may be some legal issues related to implementing this recommendation, as there are federal regulations restricting NIST and other government entities from having outside advisory committees.

1. The Ionizing Radiation Division may be losing its leading position in the national and international radiation measurements community as a result of an increasing workload in the standards area and a lack of funding to cover this increase, and the loss of personnel due to retirements and the transfer of personnel to other, fully funded programs.

2. Interviews with division management and employees conveyed the overall impression that more frequent and open communications with NIST administration on staffing, funding, and technical direction would be of benefit in giving direction to the division and in discovering ways to increase funding.

3. The process through which the Ionizing Radiation Division prioritizes and selects projects to pursue is of concern. For example, in the medical imaging area, input on clinical experience should be considered.

4. The physical plant occupied by most of the Ionizing Radiation Division equipment and personnel (Building 245) is still substandard, although some improvements have been made.

1. NIST in general and the Ionizing Radiation Division in particular need to develop a mechanism whereby the critical standards work of importance to the nation receives the necessary funding to maintain quality standards assessments.

2. The division chief and others in the division should seek advice on programs and priorities from experts in the field outside the NIST laboratory. Such advice may assist the division chief in determining which programs will allow the division to develop cutting-edge research projects to support and advance the measurements of standards in the field.

3. The Ionizing Radiation Division’s nuclear measurements and research programs are of the highest quality. Funding for these efforts should be maintained or, preferably, increased. Although there is the potential for work of Nobel Prize quality, the major goal is and should be to serve the nation in measurements, standards, and safety that underpin advances in technology throughout the country.

4. A major upgrade of Building 245 must be a priority for NIST.