Gamma camera calibration and validation for quantitative SPECT imaging with 177Lu

D’Arienzo, Marco; Cazzato, M.; Cozzella, M.L.; Cox, M G; D’Andrea, M.; Fazio, A.; Fenwick, Andrew; Iaccarino, Giuseppe; Johansson, Lena; Strigari, Lidia; Ungania, Sara; Felice, P. De

doi:10.1016/j.apradiso.2016.03.007

Cited by 44 publications

(49 citation statements)

References 37 publications

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“…An overview of the most recently applied methods for SPECT/ CT quantification with therapeutically used radionuclides, different phantom geometries, volumes, camera vendors, reconstruction methods, and the related accuracies has been provided by Tran-Gia et al (24). Table 1 shows only publications with reported accuracies of less than 10% (25)(26)(27)(28)(29)(30)(31)(32).…”

Section: Image Quantificationmentioning

confidence: 99%

The Relevance of Dosimetry in Precision Medicine

Laßmann

Eberlein

2018

J Nucl Med

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The aim of this review is to provide an overview of the most recent technologic developments in state-of-the-art equipment and tools for dosimetry in radionuclide therapies. This includes, but is not restricted to, calibration methods for imaging systems. In addition, a summary of new developments that consider the influence of small-scale dosimetry and of biologic effects on radionuclide therapies is given. Finally, the current limitations of patient-specific dosimetry such as bone-marrow dosimetry or dosimetry of α-emitters are discussed.

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Section: Image Quantificationmentioning

confidence: 99%

The Relevance of Dosimetry in Precision Medicine

Laßmann

Eberlein

2018

J Nucl Med

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“…In contrast, the calibration of each SPECT/CT system (i.e., the conversion from count rate to activity concentration) is camera-dependent. In this case, a system-specific conversion factor (cf) has to be individually determined by each site (5,6). Additionally, partial-volume errors represent a large source of error in SPECT/CT-based activity quantification (7): image enhancement techniques seek to recover the resolution directly from the emission data (8)(9)(10).…”

mentioning

confidence: 99%

“…In contrast, image-domain correction techniques try to restore spilled-out counts on the basis of anatomic information or predetermined experimental findings, such as by multiplication with a spheric recovery coefficient (11,12) or more organ-specific correction factors obtained in anthropomorphic, 3dimensional (3D) printed phantoms (13)(14)(15). Although many efforts have been made to standardize quantitative SPECT/CT imaging (5,6,16,17), the lack of a widely accepted and routinely applied standardization still impedes a comparison of quantitative SPECT/ CT acquisitions across different clinical centers and different manufacturers. This, in turn, obstructs the conduction of multicentric or longitudinal studies for validating and optimizing the therapeutic use of new radiopharmaceuticals (18).…”

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confidence: 99%

Characterization of Noise and Resolution for Quantitative ¹⁷⁷Lu SPECT/CT with xSPECT Quant

Tran-Gia

Laßmann

2018

J Nucl Med

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Quantitative SPECT/CT imaging forms the basis for internal dosimetry in molecular radiotherapies. While the conversion from counts to activity is typically performed based on conversion factors individually measured by each site, a recently introduced commercially available reconstruction (xSPECT Quant) offers a standardized and traceable calibration of SPECT/CT systems. The aim of this work was to assess the characteristics of xSPECT Quant in combination with Lu as one of the most important radionuclides used in molecular radiotherapies and to compare it to a widely used ordered subset expectation maximization reconstruction (Flash3D). In a series of Lu-filled phantom measurements, several important features were investigated for xSPECT Quant and Flash3D: Noise behavior and accuracy of the activity determination were evaluated in a large cylinder. Recovery coefficients were assessed in a hot-sphere phantom with and without background. Additionally, the resolutions were determined in a line source phantom as well as in a matched-filter resolution analysis of the hot-sphere-cold-background phantom. Both reconstruction algorithms improve the spatial resolution at the cost of noise build-up. Despite its slower convergence, Flash3D features a more efficient recovery. Although resolution recovery methods are applied within both reconstructions, partial volume errors - namely activity overestimation in the object center and spill-out of counts from the object edges - remain of relevance. In contrast to Flash3D where only the total number of updates (iterations×subsets) plays a role, the exact subdivision into iterations and subsets affected all characteristics of xSPECT Quant (optimum: 1 subset). The optimal trade-off between noise build-up and resolution improvement was found for 48 iterations and 1 subset, resulting in a quantitative accuracy of 1.2% in the Jaszczak cylinder (xSPECT Quant cross-calibrated to the dose calibrator). If the reconstruction parameters are chosen with care, both examined reconstructions can provide absolute quantitative SPECT images with high image quality (sub-centimeter resolution at an acceptable noise build-up) as well as high quantitative accuracy (given a well-calibrated Flash3D conversion from counts to activity concentration). With its standardized (and traceable) activity determination, xSPECT Quant dispenses with site-specific calibration protocols, enabling a reliable activity determination comparable across sites, which is especially useful for multi-centric molecular radiotherapy studies.

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“…Several investigations have been reported on the performance of such algorithm on radionuclides frequently used in nuclear medicine, for patient imaging as well as patient specific dosimetry. Some of the more pertinent publications include improvements in correction techniques for quantification in SPECT [4,[17][18][19][20], evaluations of the accuracy of quantitative image reconstruction techniques [21][22][23][24][25] and comparisons of resolution between SPECT/CT systems using machine-specific reconstruction algorithms [26][27][28]. In these studies, the OSEM reconstruction parameters (i.e.…”

Section: Introductionmentioning

confidence: 99%

Impact of a commercial 3D OSEM reconstruction algorithm on the 177Lu activity quantification of SPECT/CT imaging in a Molecular Radiotherapy trial

Grassi¹,

Fioroni²,

Mezzenga³

et al. 2017

Radiol Diagn Imaging

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The purpose of this study was to investigate the influence of the Ordered Subsets Expectation Maximization (OSEM) reconstruction updates implemented in the 177 Lu SPECT/CT imaging processing in molecular radiotherapy. A NEMA IEC Body Phantom TM was used to quantify activity in refillable spheres of five different sizes. Images were obtained with a hybrid dual-head SPECT-CT imaging system (Symbia T2, Siemens Medical System, Germany) with a clinical acquisition protocol, and reconstructed using a commercial 3D OSEM algorithm (Flash 3D). In the reconstruction process, different values of iterations and subsets were considered, along with a 3D Gaussian post-reconstruction filter and scatter and attenuation correction.Activity recovery coefficients were derived from the ratio between total reconstructed counts and the true activity for each sphere at each OSEM update. Recovery coefficients, and average fractional error (i.e. the weighted Root Mean Squared Error) were evaluated.At the same time, also 177 Lu spatial resolution and dead time were investigated, as matter of discussion about activity recovery coefficients.Results for spheres ≤ 5.5 ml in volume were significantly affected by the partial volume effect, causing a great bias in activity estimation for the smallest spheres. Their weighted fractional error was OSEM update dependent, ranging between 85% to 79% and 60% to 50% for the two smallest spheres, referring to values of 8 subsets-8 iterations and 16 subsets-10 iterations for the two extremes, respectively. No dead time was detected.The choice of iterations and subsets is dependent on the object size to investigate and on the desired image quality. Anyway, using a fixed number of iterations and subsets is correct for objects with volumes ≥ 5.5 ml, reaching the total count convergence in the reconstructed volumes, but the use of correction factors for compensating the partial volume effect is needed. For objects with volumes ≤ 5.5 ml the quantification becomes challenging.

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Gamma camera calibration and validation for quantitative SPECT imaging with 177Lu

Cited by 44 publications

References 37 publications

The Relevance of Dosimetry in Precision Medicine

The Relevance of Dosimetry in Precision Medicine

Characterization of Noise and Resolution for Quantitative ¹⁷⁷Lu SPECT/CT with xSPECT Quant

Impact of a commercial 3D OSEM reconstruction algorithm on the 177Lu activity quantification of SPECT/CT imaging in a Molecular Radiotherapy trial

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Gamma camera calibration and validation for quantitative SPECT imaging with 177Lu

Cited by 44 publications

References 37 publications

The Relevance of Dosimetry in Precision Medicine

The Relevance of Dosimetry in Precision Medicine

Characterization of Noise and Resolution for Quantitative 177Lu SPECT/CT with xSPECT Quant

Impact of a commercial 3D OSEM reconstruction algorithm on the 177Lu activity quantification of SPECT/CT imaging in a Molecular Radiotherapy trial

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Characterization of Noise and Resolution for Quantitative ¹⁷⁷Lu SPECT/CT with xSPECT Quant