Quantitative comparison between the commercial software STRATOS® by Philips and a homemade software for voxel-dosimetry in radiopeptide therapy

Grassi, Elisa; Fioroni, Federica; Valentina, Ferri; Mezzenga, Emilio; Sarti, Marco Antonio; Paulus, Timo; Lanconelli, Nico; Filice, Angelina; Versari, Annibale; Iori, Mauro

doi:10.1016/j.ejmp.2014.10.002

Cited by 34 publications

(35 citation statements)

References 10 publications

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“…Previous works demonstrated that  and the DVK approach can produce reliable absorbed doses in specific therapeutic scenarios. 19,29,30 Some of them focus on the calculation of the absorbed dose to limited regions of the body; in this case, even if a gamma emitter is taken into consideration, the calculation of the absorbed dose is limited to source organs (self-dose) or to organs in their proximity. Other works consider pure beta emitters such as 90 Y; in this case, only source organs receive a measurable absorbed dose because of beta particles short range.…”

Section: Discussionmentioning

confidence: 99%

“… has been recently validated on phantom and patient data, against / and a homemade software based on DVKs, in the case of 177 Lu dosimetry. 19  can read repeated PET (or SPECT) scans of a single patient to determine patient-specific pharmacokinetics at the voxel level. It also offers several coregistration tools to align functional images before cumulated activity calculation.…”

Section: B Absorbed Dose Calculationsmentioning

confidence: 99%

See 1 more Smart Citation

Model‐based versus specific dosimetry in diagnostic context: Comparison of three dosimetric approaches

Marcatili¹,

Villoing²,

Mauxion³

et al. 2015

Medical Physics

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Section: Discussionmentioning

confidence: 99%

Section: B Absorbed Dose Calculationsmentioning

confidence: 99%

Model‐based versus specific dosimetry in diagnostic context: Comparison of three dosimetric approaches

Marcatili¹,

Villoing²,

Mauxion³

et al. 2015

Medical Physics

View full text Add to dashboard Cite

show abstract

“…Zoom of 1, circular radius of rotation of 330 mm (around the phantom surface) and image matrix of 128x128 pixels were set, resulting in a 4.8 mm pixel size image. In acquisition, the energy windows of the two dominant photopeaks of 177 Lu [4] were set at 113keV ± 7.5% and 208.4keV ± 7.5%, as also described in Grassi et al [30]. As regards the lower energy photopeak, the TEW scatter correction was employed and the lower scatter window was set in the range from 87.58keV to 104.53keV (using a default window weight of 0.5), while the upper scatter window from 121.47keV to 130.51keV (using a default window weight of 0.9375).…”

Section: Spect/ct Acquisition and Reconstructionmentioning

confidence: 99%

“…As regards the lower energy photopeak, the TEW scatter correction was employed and the lower scatter window was set in the range from 87.58keV to 104.53keV (using a default window weight of 0.5), while the upper scatter window from 121.47keV to 130.51keV (using a default window weight of 0.9375). With respect to the higher energy photopeak, the DEW scatter correction was employed and the lower scatter window ranged from 171.60keV to 192.40keV (using a default window weight of 0.75) [30].…”

Section: Spect/ct Acquisition and Reconstructionmentioning

confidence: 99%

“…The images were reconstructed with the proprietary iterative Flash 3D reconstruction algorithm which includes correction for attenuation (based on energy extrapolation of the CT values from the automatically registered SPECT / CT image), compensation for scatter (estimated by means of the multiple energy windows method, and incorporated into the reconstruction) and a full collimator-detector response [30].…”

Section: Spect/ct Acquisition and Reconstructionmentioning

confidence: 99%

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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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Voxel‐based multimodel fitting method for modeling time activity curves in SPECT images

et al. 2017

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Purpose: Estimating the biodistribution and the pharmacokinetics from time-sequence SPECT images on a per-voxel basis is useful for studying activity nonuniformity or computing absorbed dose distributions by convolution of voxel kernels or Monte-Carlo radiation transport. Current approaches are either region-based, thus assuming uniform activity within the region, or voxel-based but using the same fitting model for all voxels. Methods: We propose a voxel-based multimodel fitting method (VoMM) that estimates a fitting function for each voxel by automatically selecting the most appropriate model among a predetermined set with Akaike criteria. This approach can be used to compute the time integrated activity (TIA) for all voxels in the image. To control fitting optimization that may fail due to excessive image noise, an approximated version based on trapezoid integration, named restricted method, is also studied. From this comparison, the number of failed fittings within images was estimated and analyzed. Numerical experiments were used to quantify uncertainties and feasibility was demonstrated with real patient data. Results: Regarding numerical experiments, root mean square errors of TIA obtained with VoMM were similar to those obtained with bi-exponential fitting functions, and were lower (< 5% vs. > 10%) than with single model approaches that consider the same fitting function for all voxels. Failure rates were lower with VoMM and restricted approaches than with single-model methods. On real clinical data, VoMM was able to fit 90% of the voxels and led to less failed fits than single-model approaches. On regions of interest (ROI) analysis, the difference between ROI-based and voxel-based TIA estimations was low, less than 4%. However, the computation of the mean residence time exhibited larger differences, up to 25%. Conclusions: The proposed voxel-based multimodel fitting method, VoMM, is feasible on patient data. VoMM leads organ-based TIA estimations similar to conventional ROI-based method. However, for pharmacokinetics analysis, studies of spatial heterogeneity or voxel-based absorbed dose assessment, VoMM could be used preferentially as it prevents model overfitting.

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Quantitative comparison between the commercial software STRATOS® by Philips and a homemade software for voxel-dosimetry in radiopeptide therapy

Cited by 34 publications

References 10 publications

Model‐based versus specific dosimetry in diagnostic context: Comparison of three dosimetric approaches

Model‐based versus specific dosimetry in diagnostic context: Comparison of three dosimetric approaches

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

Voxel‐based multimodel fitting method for modeling time activity curves in SPECT images

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