Browsing by Subject "Quality control"

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  • Sundell, Veli-Matti; Jousi, Mikko; Hukkinen, Katja; Blanco, Roberto; Mäkelä, Teemu; Kaasalainen, Touko (2019)
    Background: Digital breast tomosynthesis (DBT) is a three-dimensional breast imaging method. DBT vendors employ various approaches in both image acquisition and data processing, which may affect image quality and radiation exposure to patients. Objective: This study aimed to evaluate the performance of five DBT systems: Fujifilm Amulet Innovality (using both a standard mode and high-resolution mode), GE Senographe Essential, Hologic Selenia Dimensions, Planmed Clarity 3D, and Siemens Mammomat Inspiration. Materials and methods: The performance of each device and imaging technique was evaluated and compared by phantom measurements performed with four quality assurance phantoms. Technical image quality assessments consisted of measuring artefact extent, in-plane resolution, relative noise power spectrum, and geometric accuracy. Results: Artefact spreading varied remarkably between the devices, and the full width at half maximum values of artefact spread functions varied from 3.5 mm to 10.7 mm. Noticeable in-plane resolution anisotropy, determined using modulation transfer function (MTF) analysis, was typically observed between tube travel direction and chest wall-nipple direction. The MTF50 varied from 1.1 mm(-1) to 1.6 mm(-1) and from 1.5 mm(-1) to 4.1 mm(-1) in the tube travel and chest wall-nipple directions, respectively. Moreover, distinctly different noise power spectra were observed between the systems. The geometric accuracy in every system was within 0.5%. Conclusion: Technical image quality assessments with image quality phantoms revealed remarkable differences in artefact spread, in-plane resolution, and noise properties between the DBT systems and imaging methods.
  • Oja, S.; Komulainen, P.; Penttilä, A.; Nystedt, J.; Korhonen, M. (BioMed Central, 2018)
    Abstract Background Senescent cells are undesirable in cell therapy products due to reduced therapeutic activity and risk of aberrant cellular effects, and methods for assessing senescence are needed. Early-passage mesenchymal stromal cells (MSCs) are known to be small and spindle-shaped but become enlarged upon cell aging. Indeed, cell morphology is routinely evaluated during MSC production using subjective methods. We have therefore explored the possibility of utilizing automated imaging-based analysis of cell morphology in clinical cell manufacturing. Methods An imaging system was adopted for analyzing changes in cell morphology of bone marrow-derived MSCs during long-term culture. Cells taken from the cultures at the desired passages were plated at low density for imaging, representing morphological changes observed in the clinical-grade cultures. The manifestations of aging and onset of senescence were monitored by population doubling numbers, expression of p16INK4a and p21Cip1/Waf1, β-galactosidase activity, and telomeric terminal restriction fragment analysis. Results Cell area was the most statistically significant and practical parameter for describing morphological changes, correlating with biochemical senescence markers. MSCs from passages 1 (p1) and 3 (p3) were remarkably uniform in size, with cell areas between 1800 and 2500 μm2. At p5 the cells began to enlarge resulting in a 4.8-fold increase at p6–9 as compared to p1. The expression of p16INK4a and activity of β-galactosidase had a strong correlation with the increase in cell area, whereas the expression of p21Cip1/Waf1 reached its maximum at the onset of growth arrest and subsequently decreased. Mean telomere length shortened at an apparently constant rate during culture, from 8.2 ± 0.3 kbp at p1, reaching 6.08 ± 0.6 kbp at senescence. Conclusions Imaging analysis of cell morphology is a useful tool for evaluating aging in cell cultures throughout the lifespan of MSCs. Our findings suggest that imaging analysis can reproducibly detect aging-related changes in cell morphology in MSC cultures. These findings suggest that cell morphology is still a supreme measure of cell quality and may be utilized to develop new noninvasive imaging-based methods to screen and quantitate aging in clinical-grade cell cultures.
  • Oja, S.; Komulainen, P.; Penttilä, A.; Nystedt, J.; Korhonen, M. (2018)
    Background: Senescent cells are undesirable in cell therapy products due to reduced therapeutic activity and risk of aberrant cellular effects, and methods for assessing senescence are needed. Early-passage mesenchymal stromal cells (MSCs) are known to be small and spindle-shaped but become enlarged upon cell aging. Indeed, cell morphology is routinely evaluated during MSC production using subjective methods. We have therefore explored the possibility of utilizing automated imaging-based analysis of cell morphology in clinical cell manufacturing. Methods: An imaging system was adopted for analyzing changes in cell morphology of bone marrow-derived MSCs during long-term culture. Cells taken from the cultures at the desired passages were plated at low density for imaging, representing morphological changes observed in the clinical-grade cultures. The manifestations of aging and onset of senescence were monitored by population doubling numbers, expression of p16(INK4)a and p21(Cip1/Waf1), beta-galactosidase activity, and telomeric terminal restriction fragment analysis. Results: Cell area was the most statistically significant and practical parameter for describing morphological changes, correlating with biochemical senescence markers. MSCs from passages 1 (p1) and 3 (p3) were remarkably uniform in size, with cell areas between 1800 and 2500 mu m(2). At p5 the cells began to enlarge resulting in a 4.8-fold increase at p6-9 as compared to p1. The expression of p16(INK4a) and activity of beta-galactosidase had a strong correlation with the increase in cell area, whereas the expression of p21(Cip1/Waf1) reached its maximum at the onset of growth arrest and subsequently decreased. Mean telomere length shortened at an apparently constant rate during culture, from 8.2 +/- 0.3 kbp at p1, reaching 6.08 +/- 0.6 kbp at senescence. Conclusions: Imaging analysis of cell morphology is a useful tool for evaluating aging in cell cultures throughout the lifespan of MSCs. Our findings suggest that imaging analysis can reproducibly detect aging-related changes in cell morphology in MSC cultures. These findings suggest that cell morphology is still a supreme measure of cell quality and may be utilized to develop new noninvasive imaging-based methods to screen and quantitate aging in clinical-grade cell cultures.
  • Kaipio, Johanna; Karisalmi, N.; Hiekkanen, K.; Stenhammar, H.; Lahdenne, P. (IOS PRESS, 2019)
    Studies in Health Technology and Informatics
    Patient experience (PX) is an important evaluation criterion for quality in healthcare. Compared to patient satisfaction, however less research has focused on the development of instruments to measure experiences of patients and their families. In the article, we describe the process of developing a PX questionnaire for the parents of pediatric patients in the context of children's hospital and illustrate the questionnaire items for measuring PX. The phases of the development process included retrospective interviews, description of the themes influencing PX and the metrics for measuring PX, as well as iterative development of three versions of questionnaires including data gathering and factor analysis. The final versions of the surveys suggested for implementation at the hospitals include eight PX statements for the outpatient clinic and five statements for the ward. Compared to satisfaction surveys, the developed surveys emphasize the aspects of parent's attitude towards the illness, support for families, and daily arrangements with a child patient. © 2019 American Psychological Association Inc. All rights reserved.
  • Brinck, Tuomas; Heinänen, Mikko; Söderlund, Tim; Lefering, Rolf; Handolin, Lauri (2019)
    Background and aims: We aimed to determine whether the outcome of severely injured patients differs based on admission time (office hours vs. non-office hours) at a tertiary trauma centre without an in-house trauma surgeon consultant available at all times. We also studied subgroups of patients presenting with a New Injury Severity Score (NISS) >= 25 and patients experiencing major bleeding. Patients and methods: This trauma registry study consisted of severely injured patients (NISS > 15) with blunt trauma treated between 2006 and 2017 at a single institute. Causes of deaths were obtained from autopsy reports and classified as resulting from brain injury; exsanguination; multi-organ failure, adult respiratory distress syndrome, or sepsis; or other. Results: Among 1853 patients, 497 (27%) were admitted during office hours (OH) and 1356 (73%) during non-office hours (NOH). Further subgroup analysis consisted of 211 OH and 611 NOH patients with NISS >= 25, and 51 OH and 154 NOH patients experiencing major bleeding. The 30-day in-hospital mortality was 3.8%-7.4% lower in the NOH groups. We found no significant differences between the study groups in neither the standardised mortality ratio (SMR, defined as the ratio of observed to expected mortality) nor in the causes of death. In both groups, the primary cause of death resulted from brain injury. Conclusions: We found that arrival time did not affect mortality among patients with severe blunt trauma treated at a tertiary trauma centre without an in-house trauma surgeon consultant available at all times. Thus, this type of unit can maintain a standard of care during non-office hours by investing in precise treatment protocols and continuous education. However, our results do not apply to penetrating trauma injury patients. (C) 2019 Elsevier Ltd. All rights reserved.
  • Brücken, Erik; Heino, Jouni; Hildén, Timo; Kalliokoski, Matti; Litichevskyi, Vladyslav; Turpeinen, Raimo; Varga, Dezső (2021)
    It is well known and has been shown that the gain performance of Gaseous Electron Multipliers (GEM) depends on the size of the holes. With an optical scanner it is possible to measure the dimensions of the holes, and to predict the performance of GEMs. However, the gain prediction of GEMs that are manufactured with a double mask etching technique is not straightforward. With the hole size information alone, it is not possible to make precise prediction of the gain. We show that the alignment of the photo-masks between the two sides of the GEM foils plays a crucial role. A misalignment of a few microns can lower the gain substantially. The study is performed by using the Helsinki high definition optical scanner for quality control of GEM foils, and this will show its true potential.
  • Hyotylainen, Tuulia; Ahonen, Linda; Pöhö, Paivi; Oresic, Matej (2017)
    Lipids have many central physiological roles including as structural components of cell membranes, energy storage sources and intermediates in signaling pathways. Lipid-related disturbances are known to underlie many diseases and their co-morbidities. The emergence of lipidomics has empowered researchers to study lipid metabolism at the cellular as well as physiological levels at a greater depth than was previously possible. The key challenges ahead in the field of lipidomics in medical research lie in the development of experimental protocols and in silico techniques needed to study lipidomes at the systems level. Clinical questions where lipidomics may have an impact in healthcare settings also need to be identified, both from the health outcomes and health economics perspectives. This article is part of a Special Issue entitled: BBALIP_Lipidomics Opinion Articles edited by Sepp Kohlwein.
  • Nousiainen, Katri; Mäkelä, Teemu (2020)
    Objective We aimed to develop a vendor-neutral and interaction-free quality assurance protocol for measuring geometric accuracy of head and brain magnetic resonance (MR) images. We investigated the usability of nonrigid image registration in the analysis and looked for the optimal registration parameters. Materials and methods We constructed a 3D-printed phantom and imaged it with 12 MR scanners using clinical sequences. We registered a geometric-ground-truth computed tomography (CT) acquisition to the MR images using an open-source nonrigid-registration-toolbox with varying parameters. We applied the transforms to a set of control points in the CT image and compared their locations to the corresponding visually verified reference points in the MR images. Results With optimized registration parameters, the mean difference (and standard deviation) of control point locations when compared to the reference method was (0.17 +/- 0.02) mm for the 12 studied scanners. The maximum displacements varied from 0.50 to 1.35 mm or 0.89 to 2.30 mm, with vendors' distortion correction on or off, respectively. Discussion Using nonrigid CT-MR registration can provide a robust and relatively test-object-agnostic method for estimating the intra- and inter-scanner variations of the geometric distortions.
  • Peltonen, Juha I; Mäkelä, Teemu; Salli, Eero (2018)
    Objective Quality assurance (QA) of magnetic resonance imaging (MRI) often relies on imaging phantoms with suitable structures and uniform regions. However, the connection between phantom measurements and actual clinical image quality is ambiguous. Thus, it is desirable to measure objective image quality directly from clinical images. Materials and methods In this work, four measurements suitable for clinical image QA were presented: image resolution, contrast-to-noise ratio, quality index and bias index. The methods were applied to a large cohort of clinical 3D FLAIR volumes over a test period of 9.5 months. The results were compared with phantom QA. Additionally, the effect of patient movement on the presented measures was studied. Results A connection between the presented clinical QA methods and scanner performance was observed: the values reacted to MRI equipment breakdowns that occurred during the study period. No apparent correlation with phantom QA results was found. The patient movement was found to have a significant effect on the resolution and contrast-to-noise ratio values. Discussion QA based on clinical images provides a direct method for following MRI scanner performance. The methods could be used to detect problems, and potentially reduce scanner downtime. Furthermore, with the presented methodologies comparisons could be made between different sequences and imaging settings. In the future, an online QA system could recognize insufficient image quality and suggest an immediate re-scan.
  • Vitikainen, Anne-Mari; Peltonen, Juha I.; Vartiainen, Eija (2017)
    The importance of quality assurance (QA) in medical ultrasound (US) has been widely recognized and recommendations concerning technical QA have been published over the years. However, the demonstrated impact of a properly working QA protocol on clinical routine has been scarce. We investigated the transducer write-off causes for a 5-y period in a multi-unit radiology department with an annual average of 230 transducers in demanding diagnostic use. The transducer faults and the initial observers of the faults leading to transducer write-offs were traced and categorized. The most common cause of transducer write-off was an image uniformity problem or element failure. Mechanical faults or excessive leakage current and defects in the lens constituted smaller yet substantial shares. Our results suggest that a properly working routine QA program can detect majority of the faults before they are reported by users. (E-mail: juha.peltonen@hus.fi) (C) 2017 World Federation for Ultrasound in Medicine & Biology.
  • Yrjönkoski, Katariina; Jaakkola, H.; Systä, K.; Mikkonen, Tommi; Henno, J. (2019)
    During its 70 years of existence, the software business has been following an evolution curve that can be considered typical for several fields of industrial businesses. Technological breakthroughs and innovations are typically seen as enablers for business evolution in the domain of technology and innovation management. Software, data collection, and data analysis represent a greater and greater part of the value of products and services, and today, their role is also becoming essential in more traditional fields. This, however, requires business and technology competences that traditional industries do not have. The transformation also enables new ways of doing business and opens the field for new kinds of players. Together, all this leads to transformation and new possibilities for the software industry. In this paper we study the overall trajectory of the software business, and then offer some viewpoints on the change in different elements of business models. Copyright © by the paper's authors. Copying permitted only for private and academic purposes.
  • Urraca, Ruben; Huld, Thomas; Javier Martinez-de-Pison, Francisco; Sanz-Garcia, Andres (2018)
    The major sources of uncertainty in short-term assessment of global horizontal radiation (G) are the pyranometer type and their operation conditions for measurements, whereas the modeling approach and the geographic location are critical for estimations. The influence of all these factors in the uncertainty of the data has rarely been compared. Conversely, solar radiation data users are increasingly demanding more accurate uncertainty estimations. Here we compare the annual bias and uncertainty of all the mentioned factors using 732 weather stations located in Spain, two satellite-based products and three reanalyses. The largest uncertainties were associated to operational errors such as shading (bias = - 8.0%) or soiling (bias = - 9.4%), which occurred frequently in low-quality monitoring networks but are rarely detected because they pass conventional QC tests. Uncertainty in estimations greatly changed from reanalysis to satellite-based products, ranging from the gross accuracy of ERA-Interim (+ 6.1(-6.7)(+)(1)(8.)(8)%) to the high quality and spatial homogeneity of SARAH-1 (+ 1.4(-5.3)(+)(5.6)%). Finally, photodiodes from the Spanish agricultural network SIAR showed an uncertainty of (+6.)(9)(-5.4)%, which is far greater than that of secondary standards (+/- 1.5%) and similar to SARAH-1. This is probably caused by the presence of undetectable operational errors and the use of uncorrected photodiodes. Photodiode measurements from low-quality monitoring networks such as SIAR should be used with caution, because the chances of adding extra uncertainties due to poor maintenance or inadequate calibration considerably increase.