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How to experimentally test the accuracy of quantitative SPECT images?

Piwowarska-Bilska Hanna, Kurkowska Sara, Iwanowski Jacek, Poniatowska Małgorzata, Piwowarski Mateusz, Birkenfeld Bożena

Polish Journal of Medical Physics and Engineering

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2025

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Vol. 31, Iss. 2

104--109

EN

Introduction: Radiopharmaceutical therapy (RPT) uses radiopharmaceuticals that target cancer cells and is increasingly used as an oncological treatment. Estimating the absorbed dose of ionizing radiation in the patient’s organs is the basis for personalized RPT. This article presents a technique for assessing the performance of a quantitative reconstruction using NEMA phantom. The goal of this work was to compare the accuracy of quantitative SPECT images using the same reconstruction algorithm but acquired with two different SPECT/CT systems from two different manufacturers. Materials and Methods: We performed a series of SPECT/CT acquisitions of a NEMA IEC Body Phantom filled with 177Lu using two gamma cameras. The images were reconstructed and quantified using Hermes software. Results: There was no statistically significant difference in the results of recovered activities between the Symbia Intevo Bold and the NM/CT 850 gamma cameras. For a sphere with a diameter of 37 mm, the Rc values ranged from 0.69 to 0.75 for the Symbia Intevo Bold and 0.70 to 0.73 for the NM/CT 850. For a sphere with a diameter of 28 mm, the Rc values ranged from 0.61 to 0.71 for the Symbia Intevo Bold and 0.61 to 0.70 for the NM/CT 850. For a sphere with a diameter of 22 mm, the Rc values fell within the range of 0.56 to 0.63 for the Symbia Intevo Bold and 0.51 to 0.59 for the NM/CT 850. Conclusions: Quantitative SPECT images are necessary to perform dosimetry calculations and before using them in the clinical settings it is important to perform validation. This validation can be simply performed by acquiring images of the phantom filled with known activity using the same acquisition and reconstruction parameters as those employed for patients studies. In our study we observed comparable performance between images acquired by the systems from two different manufacturers.

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Efficient procedure for freeform surface accuracy assessment

Poniatowska Małgorzata

Metrology and Measurement Systems

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2025

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Vol. 32, nr 1

1--12

EN

The document provides a procedure for accuracy assessment of freeform surfaces based on CMM sampling limited to critical areas, i.e. areas of distribution of the highest deviations predicted from a theoretical or experimental CAD model of deviations. The value of the form deviation is determined by the point furthest away from the nominal CAD model, i.e. the critical point. Critical areas on the deviation model are determined taking into account the uncertainty of predicting a high of an actual surface profile at a critical point. All steps of the procedure are performed in the CAD environment. The proposed procedure is more efficient than the traditional method of distributing points over the entire surface with the same measurement uncertainty. The procedure is demonstrated by assessing the accuracy of a component after three-axis milling, using a theoretical model of the deviations.

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Digital twin in metrology: opportunities, current implementations and research challenges

Poniatowska Małgorzata, Mazurkiewicz Dariusz, Sobecki Piotr

Metrology & Hallmark

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2024

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Vol. 1

art. no. 6

EN

Digital twin (DT) technology is now popular in several research and development applications, including also metrology. Measurements as a source of data play an important role not only in DT design, modeling and implementation, but digital twins of measurement systems can also be successfully used in many applications, for example to estimate measurement uncertainty. The digital twin method has a tremendous potential and many application possibilities in metrology, therefore in this paper some up-to-date research results in this area are presented and discussed, including some representative activities of National Metrology Institutes (NMIs).

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Planning the coordinate measurements of a freeform surface after milling based on a cad model simulating the surface after machining

Werner Andrzej, Poniatowska Małgorzata

Acta Mechanica et Automatica

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2024

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Vol. 18, no. 4

730--736

EN

This paper proposes the planning of coordinate measurements of freeform surfaces based on a model simulating the surface after machining. This model is created by the determination of a theoretical tool deflection during machining. The determined components of the simulated machining deviations are used in the reconstruction of the nominal CAD model of the surface into a model simulating the geometry of the surface after machining. This model is subdivided into areas corresponding to the assumed machining deviation intervals. This makes it possible to control the number and distribution of measuring points in separate sections of the manufactured surface. Coordinate measurements of the machined surface are made in areas where maximum deviations are expected. Here, the number and distribution of measuring points are controlled over a wide range. Coordinate measurements in other areas are carried out with significantly fewer points or may be omitted altogether. This approach makes it possible to reduce the measurement time without losing important information affecting the evaluation result. The method proposed in this paper has been tested on samples containing freeform surface. The test object was manufactured using a 3-axis milling technique with a spherical end mill.