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Dosimetry Group

Welcome

The Dosimetry Group advances the measurement of quantities important in the radiological sciences through programs in the dosimetry of x-rays, gamma-rays, electrons, and other charged particles. Its mission is to develop, maintain, and disseminate the national measurement standards for these radiations, and to engage in research on radiation interactions and effects to meet requirements for new standards and to address the needs of industry, medicine, and government. These standards are disseminated both directly to the customer and through networks of secondary calibration laboratories by means of calibrations and proficiency testing services provided to maintain measurement-quality assurance traceability. We maintain the national standards for the gray, the Système International (SI) unit for radiation dosimetry, and development, maintain and disseminate high-quality data on fundamental radiation interactions. These are used extensively in radiation transport calculations and simulations, using algorithms and codes often developed by our staff, to solve a wide range of problems in radiation science and applications.

Our work on homeland-security applications continued, while significant progress was made in our more traditional radiation-dosimetry programs. The development of performance criteria for x-ray and gamma-ray screening systems used in homeland-security applications was advanced through official working groups writing ANSI standards (imaging performance of small-particle checkpoint screening systems, CT checked-baggage screening systems, vehicle/cargo inspection systems and of personnel body-scanning systems.

Significant progress has been made in a number of our measurement standards and calibration services. Our research in improved water calorimetry to realize absorbed dose continues to move forward, and our clinical electron accelerator has been used extensively in the development of a second-generation water calorimeter to serve as a national standard for accelerator-produced high-energy x-ray beams used in cancer therapy. 

We work closely with the networks of secondary calibration laboratories traceable to us and continue to expend our capabilities in a number or measurement areas. Our staff continues to make important contributions to the work of national and international standards and of scientific organizations, and we are central to measurement-quality assurance of dosimetry in the many application areas of ionizing radiation.

Programs/Projects

Accelerator Facilities—The Radiation Physics Division's accelerator facilities continue to support a broad range of research efforts in the areas of industrial and medical dosimetry, homeland security, radiation-hardness …

High-Dose Dosimetry Uncertainty Tables—The high-dose dosimetry program supports radiation-processing applications by assuring that the absorbed dose to the product, often prescribed or limited by regulatory agencies, is traceable to …

Absorbed-Dose Measurements to Support Biologics Research—The Dosimetry Group have been working with Maryland-based biotech firm Sanaria Inc. that is planning to manufacture a new vaccine against malaria.

Comparison of Co60 Absorbed Dose for High-Dose Dosimetry—NIST participated in a recent international comparison of standards for absorbed dose to water for 60Co gamma radiation at radiation-processing dose levels organized by the Bureau International des …

Dose/Dose-Rate Effects in Alanine Dosimetry—Check standards are used by the NIST Ionizing Radiation Division to monitor the performance of the alanine dosimetry system that is central to its high-dose transfer dosimetry service. 

Applications of NIST Alanine/EPR Dosimetry to the Irradiation of Blood and Blood Products—At present, irradiation of blood products with ionizing energy is the only procedure known to prevent transfusion-associated graft-versus-host disease (TA-GVHD).

New Reference Standards for Digital Mammography—New NIST reference mammography beams using a tungsten target and silver, rhodium, molybdenum and aluminum filters at 20 kV to 50 kV have been developed.

Electron and Proton Absorbed-Dose-to-Water Primary Standards—Work on absorbed-dose standards for particle beams is in progress, with preliminary results obtained for both high-energy electrons (at the NIST Clinac 2100C) and double-scattered protons (at the …

Absorbed Dose to Water and Air Kerma Calibrations in Co-60 Therapy Level Gamma-Ray Beams—Three dosimetry calibration laboratories accredited by the American Association of Physicists in Medicine (AAPM) routinely perform calibrations of a large number of instruments used in hospitals …

Development of a New 137Cs Gamma-Ray Calibration Facility—The construction of a new primary calibration facility for air kerma measurements has been completed. It delivers a collimated 137Cs gamma-ray beam in which radiation detection instruments can be …

National Air-Kerma Standard for Electronic Brachytherapy—The Dosimetry Group has developed a new facility for the calibration of the Xoft miniature x-ray source, which provides low-energy x-rays (< 50 keV) for electronic brachytherapy applications.

Air Kerma Calibrations in Radiation Protection Level 137Cs and 60Co Gamma Ray Beams—The Dosimetry Group maintains and disseminates the national measurement standards for air-kerma (exposure) from 137Cs and 60Co gamma-ray beams  and for absorbed dose to water from 60Co gamma-ray …

National and International Standards for X-ray Security Screening Applications—The primary objective of this project is to assure the technical performance and radiation safety of the nation’s x-ray and gamma-ray security screening efforts in all venues in which they are …

Digital Mammography Standards—New NIST reference mammography beams using a tungsten target and silver, rhodium, molybdenum and aluminum filters at 20 kV to 50 kV have been developed.  

A Study of the Irradiation-Temperature Coefficient for Alanine Film and Pellet Dosimeters at Elevated Temperature—Correcting the response of a dosimeter for the average temperature during irradiation processing improves the accuracy of the dose measurement. 

High-Dose Dosimetry—The activities described here support the application of high-dose, high-energy ionizing radiation for a variety of industrial processes. Radiation-induced materials modifications improve the …

Photon Absorbed-Dose-to-Water Primary Standards—Computational and experimental studies to obtain correction factors for heat defect, heat transfer and scattering/perturbation for the water calorimeter in both Co-60 and high-energy x-ray beams …

Electron-Beam Irradiation of Solar Cells—The Dosimetry Group operates a system capable of performing electron beam processing, which consists of a Van de Graaff electron accelerator and a sample scanning mechanism.

Advanced X-ray Systems for the Detection of Special Nuclear Materials—The Dosimetry Group provides support to the Domestic Nuclear Detection Office (DNDO) of the Department of Homeland Security (DHS) for their advanced non-intrusive inspection (NII) initiatives. Our …

Comparison of ANSI N42.46 and IEC 62523 Standards for Cargo and Vehicle Screening—We are undertaking a comparison of the relative performance of ANSI N42.46 and IEC 62523 consensus standards for x-ray cargo and vehicle screening.

Theoretical Dosimetry and Radiation-Transport Calculations—The fundamental photon and charged particle interaction data and the radiation transport methods, pioneered and developed at NIST to calculate the penetration of electrons and photons in matter, …

Calibration of Low-Energy Photon Brachytherapy Sources—Small radioactive "seed" sources used in prostate brachytherapy, containing the radionuclide 103Pd, 125I, or 131Cs, are calibrated in terms of air-kerma strength using the NIST Wide-Angle Free-Air …

Characterization of Dosimeters Used in Computed Tomography—In an effort to both reduce and improve the monitoring of radiation dose delivered to patients during computed tomography (CT) procedures, the Dosimetry Group has an ongoing project that involves …

NIST Work in Support of the Navy Dosimetry Program—The U.S. Navy uses thermoluminescent dosimeters (TLDs) to monitor personnel for radiation exposure.

Calibration of Beta-Particle Sources and Instruments for Radiation Protection—A calibration service for protection-level beta-particle sources and instrumentation has been in place at NIST for several years

Enhanced X-Ray Imaging—This project pursues enhanced x-ray image acquisition and analysis methods that are applicable to, for example, security and medical applications of x-ray imaging as well as basic science …

High-Resolution X-ray Spectroscopy—We are pursuing a program of x-ray spectroscopy of highly-charged ions and plasmas using custom-designed and constructed curved crystal spectrometers.

Remote Sensing Methods for Imaging Dose to Water—Calorimetry based upon remote sensing of the temperature field in an irradiated volume would offer distinct advantages over the present approach, employing thermistor probes, for the dosimetry of …

Key Comparison for Air-Kerma From Therapy Level and Radiation Protection Gamma-Ray Beams—Comparisons for the national standards of air kerma from therapy level and radiation protection gamma-ray beams were conducted by the NIST and the Bureau International des Poids et Mesures (BIPM).

Photon and Charged Particle Data Center—The Photon and Charged Particle Data Center has long been an international source of photon and charged particle reference data that have been used in stand-alone applications or integrated into …

Small-Field Therapy Dosimetry Using Alanine/EPR—NIST has an ongoing program in small-field therapy dosimetry studies using alanine/EPR.

Traceability for Industrial Irradiator—U.S. manufacturers have contended for decades that traceability to national standards for industrial irradiation applications is best achieved by services based on national laboratory facilities …

Air Kerma Measurements in High Energy X-ray Beams—Cargo-inspection systems employ high-energy x-ray beams from accelerators. These systems are designed to detect potential threats that may be present in cargo containers and vehicles that pass …

Dosimetry Standardization for Radiobiology—A program for the development of dosimetry standards for radiobiology was launched through a highly successful workshop.  The NIAID/NCI/NIST-sponsored workshop on Radiation Dosimetry …

X-Ray Standards—A new free-air ionization chamber has been built to eventually replace the Wyckoff-Attix chamber, which has been used at NIST as a primary x-ray standard for more than fifty years.

Spectrometry of X-Ray Beams Used for Calibrations—Spectrometry measurements in the x-ray calibration ranges have been undertaken using a high-resolution HPGe detector both in the direct beam and at 90 % using a Compton-scatter spectrometer.

Advancing Alanine Dosimetry for Small Radiosurgery Fields—Research is underway to expand the current range (20 Gy to 200 kGy) of alanine dosimetry to include therapy level dosimetry (as low as 1 Gy) for small-field radiation treatment applications (e.g., …

International Comparisons for Air Kerma and Absorbed Dose to Water from Gamma-ray Beams—A bilateral comparison was conducted between NIST and the International Atomic Energy Agency (IAEA) to support international efforts for harmonizing radiation protection measurements around the …

Standard Reference Data on Radiation Interactions—NIST has nearly five decades of experience in the development of critically evaluated, comprehensive databases of cross-section information for ionizing photons (x and gamma rays), electrons, and …

Evaluation of Uncertainty in Brachytherapy Dosimetry—NIST is participating in Task Group # 138 (TG-138) of the American Association of Physicists in Medicine (AAPM), AAPM Recommendations on Assessing Uncertainty of the Brachytherapy Clinical Dose …

Calibrations of a Miniature X-ray Source Used for Electronic Brachytherapy—A new laboratory dedicated to establishing a national primary air-kerma rate standard for Xoft's AXXENT™ miniature x-ray source has been fabricated.  The Xoft source was designed to provide …

Applications of Diagnostic X-ray Spectrometers—The Dosimetry Group designs, fabricates, and calibrates bent-crystal optics and diagnostic spectrometers for customers around the world.

NIST Calibrations of a Miniature X-Ray Source Used for Electronic Brachytherapy— A new laboratory dedicated to establishing a national primary air-kerma rate standard for Xoft's AXXENT™ miniature x-ray source has been fabricated

 
Staff Directory
Contact

Mitch
 

Michael G. Mitch, Group Leader

301-975-5491 Phone
301-975-5575 Group Secretary
301-869-7682 Facsimile

100 Bureau Drive, M/S 8460
Gaithersburg, MD 20899-8460

Dosimetry Group Staff Directory