TY - JOUR AU - Szirmay-Kalos, László AU - Magdics, Milán AU - Varnyú, Dóra TI - Direct dynamic tomographic reconstruction without explicit blood input function JF - BIOMEDICAL SIGNAL PROCESSING AND CONTROL J2 - BIOMED SIGNAL PROCES VL - 80 PY - 2023 PG - 10 SN - 1746-8094 DO - 10.1016/j.bspc.2022.104313 UR - https://m2.mtmt.hu/api/publication/33212860 ID - 33212860 N1 - Export Date: 8 November 2022 Correspondence Address: Szirmay-Kalos, L.; Budapest University of Technology and Economics, Hungary; email: szirmay@iit.bme.hu AB - With dynamic positron emission tomography (PET), we study the metabolic processes by monitoring the uptake of a radioactive tracer. The goal is to reconstruct the time-activity curves (TACs) of the voxels, from which the relevant kinetic parameters can be obtained. These curves are assumed to have the algebraic form of a pre-determined kinetic model. Plausible algebraic forms have a limited number of free parameters and thus can be used even for low-statistic measurements. The kinetic model typically involves the amount of radiotracer in the blood, which should be determined either by direct measurement or by extracting it from the PET data using image-derived or model-based methods. However, the direct measurement of the blood concentration is complicated, and the results of the image-derived and the model-based methods are also not reliable because of the partial volume effect and the unknown fraction of blood in the voxels. Moreover, in direct dynamic tomography, the kinetic model is fit from the very beginning of the reconstruction, thus the blood input function is needed even before the image-derived or model-based approaches can provide it. In this paper, we propose a method that is based on compartmental modeling and the Feng blood input function model defined by a fourth-order exponential equation with a pair of repeated eigenvalues, but does not require the blood input function and the fraction of blood parameters explicitly. Thus, the model can be used in cases when we wish to have the robustness and advantages of compartmental modeling, but no blood input function measurement is available. The test results show that the added error in the TACs of not knowing the blood input is reduced in comparison with the spline-based TAC representation. The method can be applied in reference tissue analysis and in image-derived input function approaches. LA - English DB - MTMT ER - TY - CHAP AU - Magdics, Milán AU - Tóth, Márton József ED - Szirmay-Kalos, L ED - Renner, Gábor TI - CT-based training data generation for DL-based X-ray image processing T2 - X. Magyar Számítógépes Grafika és Geometria Konferencia PB - Neumann János Számítógép-tudományi Társaság CY - Budapest SN - 9789634218715 PY - 2022 SP - 72 EP - 79 PG - 8 UR - https://m2.mtmt.hu/api/publication/33551047 ID - 33551047 LA - English DB - MTMT ER - TY - CHAP AU - Magdics, Milán AU - Szirmay-Kalos, László AU - Varnyú, Dóra ED - Kiss, Bálint ED - Szirmay-Kalos, László TI - Direct Tomographic Reconstruction without Explicit Blood Input Function T2 - Proceedings of the Workshop on the Advances in Information Technology 2022 PB - OSZK CY - Budapest SN - 9789634218715 PY - 2022 SP - 91 EP - 98 PG - 8 UR - https://m2.mtmt.hu/api/publication/32617907 ID - 32617907 LA - English DB - MTMT ER - TY - JOUR AU - Szirmay-Kalos, László AU - Magdics, Milán TI - Adapting Game Engines to Curved Spaces JF - VISUAL COMPUTER J2 - VISUAL COMPUT VL - 38 PY - 2022 SP - 4383 EP - 4395 PG - 13 SN - 0178-2789 DO - 10.1007/s00371-021-02303-2 UR - https://m2.mtmt.hu/api/publication/32182418 ID - 32182418 LA - English DB - MTMT ER - TY - JOUR AU - Szirmay-Kalos, László AU - Kacsó, Ágota Enikő AU - Magdics, Milán AU - Tóth, Balázs György TI - Robust Compartmental Model Fitting in Direct Emission Tomography Reconstruction JF - VISUAL COMPUTER J2 - VISUAL COMPUT VL - 38 PY - 2022 IS - 2 SP - 655 EP - 668 PG - 14 SN - 0178-2789 DO - 10.1007/s00371-020-02041-x UR - https://m2.mtmt.hu/api/publication/31836579 ID - 31836579 AB - Dynamic tomography reconstructs a time activity curve (TAC) for every voxel assuming that the algebraic form of the function is known a priori. The algebraic form derived from the analysis of compartmental models depends nonlinearly on the nonnegative parameters to be determined. Direct methods apply fitting in every iteration step. Because of the iterative nature of the maximum likelihood–expectation maximization (ML–EM) reconstruction, the fitting result of the previous step can serve as a good starting point in the current step; thus, after the first iteration we have a guess that is not far from the solution, which allows the use of gradient-based local optimization methods. However, finding good initial guesses for the first ML–EM iteration is a critical problem since gradient-based local optimization algorithms do not guarantee convergence to the global optimum if they are started at an inappropriate location. This paper examines the robust solution of the fitting problem both in the initial phase and during the ML–EM iteration. This solution is implemented on GPUs and is built into the 4D reconstruction module of the TeraTomo software. LA - English DB - MTMT ER - TY - CHAP AU - Szirmay-Kalos, László AU - Magdics, Milán ED - Theisel, Holger ED - Wimmer, Michael TI - Gaming in Elliptic Geometry T2 - 42nd Annual Conference of the European Association for Computer Graphics: Eurographics 2021: Short Papers PB - European Association for Computer Graphics CY - Vienna SN - 9783038681335 PY - 2021 SP - 5 EP - 8 PG - 4 DO - 10.2312/egs.20211010 UR - https://m2.mtmt.hu/api/publication/32070152 ID - 32070152 LA - English DB - MTMT ER - TY - CHAP AU - Szirmay-Kalos, László AU - Magdics, Milán ED - Kiss, Bálint ED - Szirmay-Kalos, László TI - Euclidean to non-Euclidean Transformation of Games T2 - Proceedings of the Workshop on the Advances of Information Technology (WAIT) 2021 PB - BME Irányítástechnika és Informatika Tanszék CY - Budapest SN - 9789634218449 PY - 2021 SP - 39 EP - 46 PG - 8 UR - https://m2.mtmt.hu/api/publication/31836817 ID - 31836817 LA - English DB - MTMT ER - TY - CHAP AU - Szirmay-Kalos, László AU - Varnyú, Dóra AU - Magdics, Milán AU - Tóth, Balázs György TI - Modeling of Depth of Interaction with Inter-crystal Scattering for PET Reconstruction T2 - 2020 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC) PB - IEEE CY - Piscataway (NJ) SN - 9781728176932 PY - 2020 SP - 1 EP - 6 PG - 6 DO - 10.1109/NSS/MIC42677.2020.9507795 UR - https://m2.mtmt.hu/api/publication/32252580 ID - 32252580 N1 - Export Date: 20 June 2022 LA - English DB - MTMT ER - TY - CHAP AU - Magdics, Milán AU - Szirmay-Kalos, László AU - Tóth, Balázs György AU - Szécsi, László ED - Szirmay-Kalos, László ED - Kiss, Bálint TI - Depth of Interaction Modeling for PET T2 - Proceedings of the Workshop on the Advances of Information Technology 2020 : WAIT 2020 PB - Budapesti Műszaki és Gazdaságtudományi Egyetem, Villamosmérnöki és Informatikai Kar CY - Budapest SN - 9789634218029 PY - 2020 SP - 79 EP - 88 PG - 10 UR - https://m2.mtmt.hu/api/publication/31310772 ID - 31310772 LA - English DB - MTMT ER - TY - CHAP AU - Tóth, Márton József AU - Kacsó, Ágota Enikő AU - Magdics, Milán AU - Salvi, Péter ED - Szirmay-Kalos, László ED - Kiss, Bálint TI - Advances in the visualization framework for vehicle intelligence simulations T2 - Proceedings of the Workshop on the Advances of Information Technology 2020 : WAIT 2020 PB - Budapesti Műszaki és Gazdaságtudományi Egyetem, Villamosmérnöki és Informatikai Kar CY - Budapest SN - 9789634218029 PY - 2020 SP - 1 EP - 4 PG - 4 UR - https://m2.mtmt.hu/api/publication/31166177 ID - 31166177 LA - English DB - MTMT ER -