Calibration of Traceable Solid Mock 131I Phantoms Used in an International SPECT Image Quantification Comparison

Zimmerman, Brian E.; Pibida, Leticia S.; King, Lynne E.; Bergeron, Denis E.; Cessna, Jeffrey T.; Mille, Marie-Laure

doi:10.6028/jres.118.017

Cited by 9 publications

(7 citation statements)

References 15 publications

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“…The phantom sources that were distributed to the participants were the same as those described in [19]. Briefly, each distributed set consisted of four 133 Ba epoxy-filled poly(methyl methacrylate) (PMMA) cylinders, each having an active epoxy length of 3.8 cm and inside diameters of 0.794 cm, 1.27 cm, 1.43 cm, and 2.86 cm to give nominal volumes of 2 mL, 4 mL, 6 mL, 23 mL, respectively.…”

Section: Methodsmentioning

confidence: 99%

Multi-centre evaluation of accuracy and reproducibility of planar and SPECT image quantification: An IAEA phantom study

Zimmerman

Grošev

Buvat

et al. 2017

Zeitschrift für Medizinische Physik

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Accurate quantitation of activity provides the basis for internal dosimetry of targeted radionuclide therapies. This study investigated quantitative imaging capabilities at sites with a variety of experience and equipment and assessed levels of errors in activity quantitation in Single-Photon Emission Computed Tomography (SPECT) and planar imaging. Participants from 9 countries took part in a comparison in which planar, SPECT and SPECT with X ray computed tomography (SPECT-CT) imaging were used to quantify activities of four epoxy-filled cylinders containing 133Ba, which was chosen as a surrogate for 131I. The sources, with nominal volumes of 2, 4, 6 and 23 mL, were calibrated for 133Ba activity by the National Institute of Standards and Technology, but the activity was initially unknown to the participants. Imaging was performed in a cylindrical phantom filled with water. Two trials were carried out in which the participants first estimated the activities using their local standard protocols, and then repeated the measurements using a standardized acquisition and analysis protocol. Finally, processing of the imaging data from the second trial was repeated by a single centre using a fixed protocol. In the first trial, the activities were underestimated by about 15% with planar imaging. SPECT with Chang’s first order attenuation correction (Chang-AC) and SPECT-CT overestimated the activity by about 10%. The second trial showed moderate improvements in accuracy and variability. Planar imaging was subject to methodological errors, e.g., in the use of a transmission scan for attenuation correction. The use of Chang-AC was subject to variability from the definition of phantom contours. The project demonstrated the need for training and standardized protocols to achieve good levels of quantitative accuracy and precision in a multi-centre setting. Absolute quantification of simple objects with no background was possible with the strictest protocol to about 6% with planar imaging and SPECT (with Chang-AC) and within 2% for SPECT-CT.

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Section: Methodsmentioning

confidence: 99%

Multi-centre evaluation of accuracy and reproducibility of planar and SPECT image quantification: An IAEA phantom study

Zimmerman

Grošev

Buvat

et al. 2017

Zeitschrift für Medizinische Physik

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“…During the experiments described in Zimmerman, et al (2013), four 5 mL NIST ampoules were prepared, each containing nominally 4.4 MBq·g −1 of 133 Ba in 5 g of a carrier solution of 5 mmol·L −1 BaCl 2 in 0.5 mol·L −1 HCl. Two of those ampoules, denoted Ba-D1-A3 and Ba-D1-A4, were also used in the present study (the solutions from the other two ampoules were used in experiments not related to this study).…”

Section: Methodsmentioning

confidence: 99%

“…Two of those ampoules, denoted Ba-D1-A3 and Ba-D1-A4, were also used in the present study (the solutions from the other two ampoules were used in experiments not related to this study). The total 133 Ba activities for Ba-D1-A3 and Ba-D1-A4 were calibrated by measurement in NIST “4π” γ ionization chamber “A” (IC “A”) as previously described (Zimmerman, et al 2013) and found to be 22.57(15) MBq and 20.01(13) MBq at the reference time, respectively. The uncertainties are the combined standard uncertainties on the IC “A” measurements calculated as described in Zimmerman et al (2013).…”

Section: Methodsmentioning

confidence: 99%

“…The main photon energies ( 360 keV) and total photon energies per decay are about the same for both radionuclides. These properties make 133 Ba an especially interesting surrogate for 131 I in physics studies for single photon emission computed tomography (SPECT) imaging, and in fact a set of calibrated 133 Ba sources has been successfully used in a recent international single photon emission computed tomography SPECT image quantification comparison organized by the IAEA (Zimmerman, et al 2013). …”

Section: Introductionmentioning

confidence: 99%

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(Mis)use of 133 Ba as a calibration surrogate for 131 I in clinical activity calibrators

Zimmerman

Bergeron

2016

Applied Radiation and Isotopes

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Using NIST-calibrated solutions of 131Ba and 131I in the 5 mL NIST ampoule geometry, measurements were made in three NIST-maintained Capintec activity calibrators and the NIST Vinten 671 ionization chamber to evaluate the suitability of using 133Ba as a calibration surrogate for 131I. For the Capintec calibrators, the 133Ba response was a factor of about 300% higher than that of the same amount of 131I. For the Vinten 671, the Ba-133 response was about 7 % higher than that of 131I. These results demonstrate that 133Ba is a poor surrogate for 131I. New calibration factors for these radionuclides in the ampoule geometry for the Vinten 671 and Capintec activity calibrators were also determined.

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“…Thus the sensitivity for a small source can vary with lateral position. To investigate, two cylindrical 133 Ba sources (Zimmerman et al 2013) with larger dimensions than the disk source were also imaged to evaluate the effect of the source size on the calibration factor repeatability. The active volumes of both rods were 3.8 cm long and consisted of an acrylic shell filled with epoxy containing uniformly distributed Ba-133.…”

Section: Methodsmentioning

confidence: 99%

Factors affecting the repeatability of gamma camera calibration for quantitative imaging applications using a sealed source

et al. 2015

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Several applications in nuclear medicine require absolute activity quantification of single photon emission computed tomography images. Obtaining a repeatable calibration factor that converts voxel values to activity units is essential for these applications. Because source preparation and measurement of the source activity using a radionuclide activity meter are potential sources of variability, this work investigated instrumentation and acquisition factors affecting repeatability using planar acquisition of sealed sources. The calibration factor was calculated for different acquisition and geometry conditions to evaluate the effect of the source size, lateral position of the source in the camera field of-view (FOV), source-to-camera distance (SCD), and variability over time using sealed Ba-133 sources. A small region of interest (ROI) based on the source dimensions and collimator resolution was investigated to decrease the background effect. A statistical analysis with a mixed-effects model was used to evaluate quantitatively the effect of each variable on the global calibration factor variability. A variation of 1 cm in the measurement of the SCD from the assumed distance of 17 cm led to a variation of 1–2% in the calibration factor measurement using a small disc source (0.4 cm diameter) and less than 1% with a larger rod source (2.9 cm diameter). The lateral position of the source in the FOV and the variability over time had small impacts on calibration factor variability. The residual error component was well estimated by Poisson noise. Repeatability of better than 1% in a calibration factor measurement using a planar acquisition of a sealed source can be reasonably achieved. The best reproducibility was obtained with the largest source with a count rate much higher than the average background in the ROI, and when the SCD was positioned within 5 mm of the desired position. In this case, calibration source variability was limited by the quantum noise.

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Calibration of Traceable Solid Mock 131I Phantoms Used in an International SPECT Image Quantification Comparison

Cited by 9 publications

References 15 publications

Multi-centre evaluation of accuracy and reproducibility of planar and SPECT image quantification: An IAEA phantom study

Multi-centre evaluation of accuracy and reproducibility of planar and SPECT image quantification: An IAEA phantom study

(Mis)use of 133 Ba as a calibration surrogate for 131 I in clinical activity calibrators

Factors affecting the repeatability of gamma camera calibration for quantitative imaging applications using a sealed source

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