Albert Hirtl1, Helmar Bergmann2, Barbara Knäusl3, Thomas Beyer2, Michael Figl2, Johann Hummel2. 1. Division of Nuclear Medicine, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Austria. 2. Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Austria. 3. Department of Radiation Oncology & Christian Doppler Laboratory for Medical Radiation Physics for Radiation Oncology, Medical University of Vienna, Austria.
Abstract
PURPOSE: Inspection and quantitative validation of tomographic imaging properties of SPECT systems, i.e., spatial resolution, contrast, and inhomogeneity must be performed in regular intervals. Typically, the modular Jaszczak phantom is used for that purpose, as it offers the possibility to investigate all three system properties with a single measurement. The interpretation of the measurement is performed visually, thus, being insensitive to subtle changes in system performance. To overcome this limitation, a fully-automated software for the objective analysis of Jaszczak phantom measurements is proposed here. METHODS: The software was developed as an ImageJ plugin and offers a number of sequential evaluation steps: automatic determination of the type of Jaszczak phantom, calculation of sector and sphere contrast, detection of ring artifacts using either the Hough transform, followed by a threshold-based decision criterion, or Student's t-test. Monte Carlo simulations were used to estimate the detectability limits for ring artifacts. RESULTS: The software successfully calculated sector and sphere contrasts and reliably determined ring artifacts present in the homogeneity part of the Jaszczak phantom, based on automatic identification of the phantom type. CONCLUSION: Given the quantitative nature of the produced output, results from one imaging system can easily be compared to another in an objective way. The advantage of the software is clearly that the information provided is objective and does not rely on the experience level of the user.
PURPOSE: Inspection and quantitative validation of tomographic imaging properties of SPECT systems, i.e., spatial resolution, contrast, and inhomogeneity must be performed in regular intervals. Typically, the modular Jaszczak phantom is used for that purpose, as it offers the possibility to investigate all three system properties with a single measurement. The interpretation of the measurement is performed visually, thus, being insensitive to subtle changes in system performance. To overcome this limitation, a fully-automated software for the objective analysis of Jaszczak phantom measurements is proposed here. METHODS: The software was developed as an ImageJ plugin and offers a number of sequential evaluation steps: automatic determination of the type of Jaszczak phantom, calculation of sector and sphere contrast, detection of ring artifacts using either the Hough transform, followed by a threshold-based decision criterion, or Student's t-test. Monte Carlo simulations were used to estimate the detectability limits for ring artifacts. RESULTS: The software successfully calculated sector and sphere contrasts and reliably determined ring artifacts present in the homogeneity part of the Jaszczak phantom, based on automatic identification of the phantom type. CONCLUSION: Given the quantitative nature of the produced output, results from one imaging system can easily be compared to another in an objective way. The advantage of the software is clearly that the information provided is objective and does not rely on the experience level of the user.
Authors: Pawel J Markiewicz; Casper da Costa-Luis; J Dickson; A Barnes; G Krokos; J MacKewn; T Clark; C Wimberley; G MacNaught; M M Yaqub; J D Gispert; B F Hutton; P Marsden; A Hammers; A J Reader; S Ourselin; K Herholz; J C Matthews; F Barkhof Journal: Med Phys Date: 2022-03-31 Impact factor: 4.506
Authors: Tutku E Tazegul; Andrew M Polemi; Angela Snyder; Carl Snyder; Patricia G Collins Journal: J Appl Clin Med Phys Date: 2020-11-03 Impact factor: 2.243