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Radiation-based quantitative bioimaging at the national institute of standards and technology.

Karam LR - J Med Phys (2009)

Bottom Line: Building on a long history of providing physical measurements and standards for medical X rays and nuclear medicine radionuclides, the laboratory has expanded its focus to better support the extensive use of medical physics in the United States today, providing confidence in key results needed for drug and device development and marketing, therapy planning and efficacy and disease screening.X-ray measurements of the laboratory's recently developed small, resilient and inexpensive length standard phantom have shown the potential usefulness of such a "pocket" phantom for patient-based calibration of computed tomography (alone or with PET) systems.The ability to calibrate diagnostic imaging tools in a way that is traceable to national standards will lead to a more quantitative approach; both physician and patient benefit from increased accuracy in treatment planning, as well as increased safety for the patient.

View Article: PubMed Central - PubMed

Affiliation: Ionizing Radiation Division, National Institute of Standards and Technology, 100 Bureau Dr. MS 8460, Gaithersburg, MD 20899-8460, USA.

ABSTRACT
Building on a long history of providing physical measurements and standards for medical X rays and nuclear medicine radionuclides, the laboratory has expanded its focus to better support the extensive use of medical physics in the United States today, providing confidence in key results needed for drug and device development and marketing, therapy planning and efficacy and disease screening. In particular, to support more quantitative medical imaging, this laboratory has implemented a program to provide key measurement infrastructure to support radiation-based imaging through developing standard, benchmark phantoms, which contain radioactive sources calibrated to national measurement standards, to allow more quantitative imaging through traceable instrument calibration for clinical trials or patient management. Working closely with colleagues at the National Institutes of Health, Rensselaer Polytechnic Institute, the Food and Drug Administration and Cornell University, this laboratory has taken the initial steps in developing phantoms, and the protocols to use them, for more accurate calibration of positron emission tomography (PET) or single-photon emission computed tomography (SPECT) cameras, including recently standardizing (68)Ge. X-ray measurements of the laboratory's recently developed small, resilient and inexpensive length standard phantom have shown the potential usefulness of such a "pocket" phantom for patient-based calibration of computed tomography (alone or with PET) systems. The ability to calibrate diagnostic imaging tools in a way that is traceable to national standards will lead to a more quantitative approach; both physician and patient benefit from increased accuracy in treatment planning, as well as increased safety for the patient.

No MeSH data available.


New phantom, designed and constructed at this laboratory, for PET instrumentation calibrations (“cold” epoxy version; will contain Ge-68)
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Figure 0002: New phantom, designed and constructed at this laboratory, for PET instrumentation calibrations (“cold” epoxy version; will contain Ge-68)

Mentions: Although the radionuclides used in PET procedures are extremely short lived (one of the most common, 18F, has a half-life of about 110 minutes), a longer-lived surrogate must be used in an SRM phantom for PET in order to allow for distribution to most users. Conventionally, 68Ge (t1/2 = 271 d) has been used to calibrate instrumentation and to assess PET attenuation, but has not been useable as a cross-center reference as measurement of its activity has not been traceable to a national standard, which, until recently, did not exist. In addition, calibration of 68Ge in various relevant geometries (eg, syringe, phantom) had yet to be done. In 2008, the first national calibration of 68Ge (in equilibrium with its daughter, 68Ga) was developed in this laboratory,[7] and we have been working with RadQual, LLC, for developing calibrations in a variety of geometries. The first such geometry, a phantom that could be used for instrumentation calibration[Figure 2], has been developed and is currently undergoing testing. Produced via the incorporation of calibrated 68Ge into an epoxy matrix, this phantom would be a relatively stable (over 1 year) artefact that could be used for consistent calibration of and comparisons among PET instrumentation. A calibration for the syringe geometry (in liquid and epoxy) is also underway. The 68Ge calibration has been linked back to the national 18F standard (which is calibrated for the NIH PET Center and for PETNET Solutions, a regional distributor) in order to provide traceable measurements for injected activity. Compared to measurements of the same geometry of 18F in four clinical-style dose calibrators, the response factor (ie, the relative response of a dose calibrator while the setting for 18F is used in the measurement of the same geometry of 68Ge) for the 68Ge in a syringe was determined to be 1.054 ± 0.020; Monte Carlo calculations predict this factor to be 1.053. The primary calibration has been transferred to the laboratory's 4πγ Secondary Standard Ionization Chamber to facilitate more routine future calibrations; because Monte Carlo modeling predicts about a 0.1% difference in ionization chamber response between liquid- and epoxy-filled syringes for 68Ge, no correction due to the change in matrix need be applied.


Radiation-based quantitative bioimaging at the national institute of standards and technology.

Karam LR - J Med Phys (2009)

New phantom, designed and constructed at this laboratory, for PET instrumentation calibrations (“cold” epoxy version; will contain Ge-68)
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2807674&req=5

Figure 0002: New phantom, designed and constructed at this laboratory, for PET instrumentation calibrations (“cold” epoxy version; will contain Ge-68)
Mentions: Although the radionuclides used in PET procedures are extremely short lived (one of the most common, 18F, has a half-life of about 110 minutes), a longer-lived surrogate must be used in an SRM phantom for PET in order to allow for distribution to most users. Conventionally, 68Ge (t1/2 = 271 d) has been used to calibrate instrumentation and to assess PET attenuation, but has not been useable as a cross-center reference as measurement of its activity has not been traceable to a national standard, which, until recently, did not exist. In addition, calibration of 68Ge in various relevant geometries (eg, syringe, phantom) had yet to be done. In 2008, the first national calibration of 68Ge (in equilibrium with its daughter, 68Ga) was developed in this laboratory,[7] and we have been working with RadQual, LLC, for developing calibrations in a variety of geometries. The first such geometry, a phantom that could be used for instrumentation calibration[Figure 2], has been developed and is currently undergoing testing. Produced via the incorporation of calibrated 68Ge into an epoxy matrix, this phantom would be a relatively stable (over 1 year) artefact that could be used for consistent calibration of and comparisons among PET instrumentation. A calibration for the syringe geometry (in liquid and epoxy) is also underway. The 68Ge calibration has been linked back to the national 18F standard (which is calibrated for the NIH PET Center and for PETNET Solutions, a regional distributor) in order to provide traceable measurements for injected activity. Compared to measurements of the same geometry of 18F in four clinical-style dose calibrators, the response factor (ie, the relative response of a dose calibrator while the setting for 18F is used in the measurement of the same geometry of 68Ge) for the 68Ge in a syringe was determined to be 1.054 ± 0.020; Monte Carlo calculations predict this factor to be 1.053. The primary calibration has been transferred to the laboratory's 4πγ Secondary Standard Ionization Chamber to facilitate more routine future calibrations; because Monte Carlo modeling predicts about a 0.1% difference in ionization chamber response between liquid- and epoxy-filled syringes for 68Ge, no correction due to the change in matrix need be applied.

Bottom Line: Building on a long history of providing physical measurements and standards for medical X rays and nuclear medicine radionuclides, the laboratory has expanded its focus to better support the extensive use of medical physics in the United States today, providing confidence in key results needed for drug and device development and marketing, therapy planning and efficacy and disease screening.X-ray measurements of the laboratory's recently developed small, resilient and inexpensive length standard phantom have shown the potential usefulness of such a "pocket" phantom for patient-based calibration of computed tomography (alone or with PET) systems.The ability to calibrate diagnostic imaging tools in a way that is traceable to national standards will lead to a more quantitative approach; both physician and patient benefit from increased accuracy in treatment planning, as well as increased safety for the patient.

View Article: PubMed Central - PubMed

Affiliation: Ionizing Radiation Division, National Institute of Standards and Technology, 100 Bureau Dr. MS 8460, Gaithersburg, MD 20899-8460, USA.

ABSTRACT
Building on a long history of providing physical measurements and standards for medical X rays and nuclear medicine radionuclides, the laboratory has expanded its focus to better support the extensive use of medical physics in the United States today, providing confidence in key results needed for drug and device development and marketing, therapy planning and efficacy and disease screening. In particular, to support more quantitative medical imaging, this laboratory has implemented a program to provide key measurement infrastructure to support radiation-based imaging through developing standard, benchmark phantoms, which contain radioactive sources calibrated to national measurement standards, to allow more quantitative imaging through traceable instrument calibration for clinical trials or patient management. Working closely with colleagues at the National Institutes of Health, Rensselaer Polytechnic Institute, the Food and Drug Administration and Cornell University, this laboratory has taken the initial steps in developing phantoms, and the protocols to use them, for more accurate calibration of positron emission tomography (PET) or single-photon emission computed tomography (SPECT) cameras, including recently standardizing (68)Ge. X-ray measurements of the laboratory's recently developed small, resilient and inexpensive length standard phantom have shown the potential usefulness of such a "pocket" phantom for patient-based calibration of computed tomography (alone or with PET) systems. The ability to calibrate diagnostic imaging tools in a way that is traceable to national standards will lead to a more quantitative approach; both physician and patient benefit from increased accuracy in treatment planning, as well as increased safety for the patient.

No MeSH data available.