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Norrman, Eva
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Publications (10 of 13) Show all publications
Piippo-Huotari, O., Norrman, E., Anderzen-Carlsson, A. & Geijer, H. (2018). New patient-controlled abdominal compression method in radiography: radiation dose and image quality. Acta radiologica open, 7(5), 1-8, Article ID 2058460118772863.
Open this publication in new window or tab >>New patient-controlled abdominal compression method in radiography: radiation dose and image quality
2018 (English)In: Acta radiologica open, ISSN 2058-4601, Vol. 7, no 5, p. 1-8, article id 2058460118772863Article in journal (Refereed) Published
Abstract [en]

Background: The radiation dose for patients can be reduced with many methods and one way is to use abdominal compression. In this study, the radiation dose and image quality for a new patient-controlled compression device were compared with conventional compression and compression in the prone position.

Purpose: To compare radiation dose and image quality of patient-controlled compression compared with conventional and prone compression in general radiography.

Material and Methods: An experimental design with quantitative approach. After obtaining the approval of the ethics committee, a consecutive sample of 48 patients was examined with the standard clinical urography protocol. The radiation doses were measured as dose-area product and analyzed with a paired t-test. The image quality was evaluated by visual grading analysis. Four radiologists evaluated each image individually by scoring nine criteria modified from the European quality criteria for diagnostic radiographic images.

Results: There was no significant difference in radiation dose or image quality between conventional and patient-controlled compression. Prone position resulted in both higher dose and inferior image quality.

Conclusion: Patient-controlled compression gave similar dose levels as conventional compression and lower than prone compression. Image quality was similar with both patient-controlled and conventional compression and was judged to be better than in the prone position.

Place, publisher, year, edition, pages
Sage Publications, 2018
Keywords
Compression, X-ray, image quality, radiation dose, radiography
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:oru:diva-67002 (URN)10.1177/2058460118772863 (DOI)000434653700001 ()29760949 (PubMedID)
Note

Funding Agencies:

Research Committee of Region Örebro County  

Örebro University, Sweden 

Available from: 2018-05-23 Created: 2018-05-23 Last updated: 2018-07-24Bibliographically approved
Alshamari, M., Geijer, M., Norrman, E., Lidén, M., Krauss, W., Jendeberg, J., . . . Geijer, H. (2017). Impact of iterative reconstruction on image quality of low-dose CT of the lumbar spine. Acta Radiologica, 58(6), 702-709
Open this publication in new window or tab >>Impact of iterative reconstruction on image quality of low-dose CT of the lumbar spine
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2017 (English)In: Acta Radiologica, ISSN 0284-1851, E-ISSN 1600-0455, Vol. 58, no 6, p. 702-709Article in journal (Refereed) Published
Abstract [en]

Background: Iterative reconstruction (IR) is a recent reconstruction algorithm for computed tomography (CT) that can be used instead of the standard algorithm, filtered back projection (FBP), to reduce radiation dose and/or improve image quality.

Purpose: To evaluate and compare the image quality of low-dose CT of the lumbar spine reconstructed with IR to conventional FBP, without further reduction of radiation dose.

Material and Methods: Low-dose CT on 55 patients was performed on a Siemens scanner using 120 kV tube voltage, 30 reference mAs, and automatic dose modulation. From raw CT data, lumbar spine CT images were reconstructed with a medium filter (B41f) using FBP and four levels of IR (levels 2-5). Five reviewers scored all images on seven image quality criteria according to the European guidelines on quality criteria for CT, using a five-grade scale. A side-by-side comparison was also performed.

Results: There was significant improvement in image quality for IR (levels 2-4) compared to FBP. According to visual grading regression, odds ratios of all criteria with 95% confidence intervals for IR2, IR3, IR4, and IR5 were: 1.59 (1.39-1.83), 1.74 (1.51-1.99), 1.68 (1.46-1.93), and 1.08 (0.94-1.23), respectively. In the side-by-side comparison of all reconstructions, images with IR (levels 2-4) received the highest scores. The mean overall CTDIvol was 1.70 mGy (SD 0.46; range, 1.01-3.83 mGy). Image noise decreased in a linear fashion with increased strength of IR.

Conclusion: Iterative reconstruction at levels 2, 3, and 4 improves image quality of low-dose CT of the lumbar spine compared to FPB.

Place, publisher, year, edition, pages
London: Sage Publications, 2017
Keywords
X-ray computed tomography (CT), image manipulation/reconstruction, lumbar vertebrae, radiation dosage, spine
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:oru:diva-57646 (URN)10.1177/0284185116669870 (DOI)000399995700011 ()28157395 (PubMedID)2-s2.0-85019010032 (Scopus ID)
Available from: 2017-05-12 Created: 2017-05-12 Last updated: 2019-03-26Bibliographically approved
Andersson, K. M., Norrman, E., Geijer, H., Krauss, W., Cao, Y., Jendeberg, J., . . . Thunberg, P. (2016). Visual grading evaluation of commercially available metal artefact reduction techniques in hip prosthesis computed tomography. British Journal of Radiology, 89(1063), Article ID 20150993.
Open this publication in new window or tab >>Visual grading evaluation of commercially available metal artefact reduction techniques in hip prosthesis computed tomography
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2016 (English)In: British Journal of Radiology, ISSN 0007-1285, E-ISSN 1748-880X, Vol. 89, no 1063, article id 20150993Article in journal (Refereed) Published
Abstract [en]

Objectives: To evaluate metal artefact reduction (MAR) techniques from four computed tomography (CT) vendors in hip prosthesis imaging.

Methods: Bilateral hip prosthesis phantom images, obtained by using MAR algorithms for single energy CT data or dual energy CT (DECT) data and by monoenergetic reconstructions of DECT data, were visually graded by five radiologists using ten image quality criteria. Comparisons between the MAR images and a reference image were performed for each scanner separately. Ordinal probit regression analysis was used.

Results: The MAR algorithms in general improved the image quality based on the majority of the criteria (up to between 8/10 and 10/10) with a statistically improvement in overall image quality (P<0.001). However, degradation of image quality, such as new artefacts, was seen in some cases. A few monoenergetic reconstruction series improved the image quality (P<0.004) for one of the DECT scanners, but it was only improved for some of the criteria (up to 5/10). Monoenergetic reconstructions resulted in worse image quality for the majority of the criteria (up to 7/10) for the other DECT scanner.

Conclusions: The MAR algorithms improved the image quality of the hip prosthesis CT images. However, since additional artefacts and degradation of image quality were seen in some cases, all algorithms should be carefully evaluated for every clinical situation. Monoenergetic reconstructions were in general concluded to be insufficient for reducing metal artifacts. Advances in knowledge: Qualitative evaluation of the usefulness of several MAR techniques from different vendors in CT imaging of hip prosthesis.

Place, publisher, year, edition, pages
London, United Kingdom: British Institute of Radiology, 2016
National Category
Radiology, Nuclear Medicine and Medical Imaging
Research subject
Radiology
Identifiers
urn:nbn:se:oru:diva-50103 (URN)10.1259/bjr.20150993 (DOI)000378096400009 ()27123700 (PubMedID)
Available from: 2016-05-03 Created: 2016-05-03 Last updated: 2019-04-12Bibliographically approved
Andersson, K. M., Nowik, P., Persliden, J., Thunberg, P. & Norrman, E. (2015). Metal artefact reduction in CT imaging of hip prostheses-an evaluation of commercial techniques provided by four vendors. British Journal of Radiology, 88(1052), Article ID 20140473.
Open this publication in new window or tab >>Metal artefact reduction in CT imaging of hip prostheses-an evaluation of commercial techniques provided by four vendors
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2015 (English)In: British Journal of Radiology, ISSN 0007-1285, E-ISSN 1748-880X, Vol. 88, no 1052, article id 20140473Article in journal (Refereed) Published
Abstract [en]

Objective: The aim of this study was to evaluate commercial metal artefact reduction (MAR) techniques in X-ray CT imaging of hip prostheses.

Methods: Monoenergetic reconstructions of dual-energy CT (DECT) data and several different MAR algorithms, combined with single-energy CT or DECT, were evaluated by imaging a bilateral hip prosthesis phantom. The MAR images were compared with uncorrected images based on CT number accuracy and noise in different regions of interest.

Results: The three MAR algorithms studied implied a general noise reduction (up to 67%, 74% and 77%) and an improvement in CT number accuracy, both in regions close to the prostheses and between the two prostheses. The application of monoenergetic reconstruction, without any MAR algorithm, did not decrease the noise in the regions close to the prostheses to the same extent as did the MAR algorithms and even increased the noise in the region between the prostheses.

Conclusion: The MAR algorithms evaluated generally improved CT number accuracy and substantially reduced the noise in the hip prostheses phantom images, both close to the prostheses and between the two prostheses. The study showed that the monoenergetic reconstructions evaluated did not sufficiently reduce the severe metal artefact caused by large orthopaedic implants.

Advances in knowledge: This study evaluates several commercially available MAR techniques in CT imaging of large orthopaedic implants.

Place, publisher, year, edition, pages
British Institute of Radiology, 2015
National Category
Radiology, Nuclear Medicine and Medical Imaging
Research subject
Radiology
Identifiers
urn:nbn:se:oru:diva-46510 (URN)10.1259/bjr.20140473 (DOI)000363313000002 ()26110201 (PubMedID)2-s2.0-84938837932 (Scopus ID)
Available from: 2015-11-17 Created: 2015-11-16 Last updated: 2018-09-04Bibliographically approved
Andersson, K. M., Norrman, E. & Thunberg, P. (2015). Metal Artifacts in CT Imaging of Hip Prostheses: Evaluation of Metal Artifact Reduction Techniques Provided by Four Vendors. In: : . Paper presented at Radiological Society of North America (RSNA 2015), Chicago, USA, November 29 - December 4, 2015.
Open this publication in new window or tab >>Metal Artifacts in CT Imaging of Hip Prostheses: Evaluation of Metal Artifact Reduction Techniques Provided by Four Vendors
2015 (English)Conference paper, Poster (with or without abstract) (Other academic)
Abstract [en]

PURPOSE: The aim of this study was to evaluate metal artifact reduction (MAR) techniques, provided by four vendors, in CT imaging of hip prostheses.

METHOD AND MATERIALS: A water phantom containing hip prostheses mounted in calf bones was scanned with four CT scanners; Philips Ingenuity; Toshiba Aquilion ONE Vision edition; GE Discovery 750 HD and Siemens SOMATOM Definition Flash. An uncorrected (reference) image was obtained for every CT and compared with images acquired with the scanner specific MAR technique; either monoenergetic reconstruction of Dual Energy CT (DECT) data (GE and Siemens) or the use of a MAR algorithm software (Philips and Toshiba), or a combination of the two (GE). The MAR techniques were applied for varying tube voltage, kernel and reconstruction technique. The reference images were quantitatively compared to the MAR images by analyzing the noise and the CT number accuracy in region of interests (ROIs). Visual grading was performed by five radiologists based on ten image quality (IQ) criteria.

RESULTS: The MAR algorithms implied a general noise reduction (by up to 77%) and improved IQ based on the majority of the visual grading criteria. The use of monoenergetic reconstructions of DECT data, without any MAR algorithm, did not decrease the noise in the ROIs to the same extent as the MAR algorithms (up to 41%) and did even increase the noise in one ROI. The visual grading evaluation showed that monoenergetic reconstructions in general degraded the IQ for one of the DECT scanners and improved the IQ for only a few of the criteria for the other DECT scanner.

CONCLUSION: The quantitative analysis and the visual grading evaluation showed that the IQ was generally improved when the MAR algorithms were used. However, additional artifacts and degradation of the IQ were noted in some MAR image regions. The use of monoenergetic reconstruction was concluded to not reduce metal artifacts to the same extent as the MAR algorithms and to even degrade the IQ in several image regions.

CLINICAL RELEVANCE/APPLICATION: This study points out advantages and potential risks of using MAR techniques in CT imaging of hip prostheses and will be useful for clinics when optimizing CT scan protocols and purchasing new CT systems.

National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:oru:diva-63495 (URN)
Conference
Radiological Society of North America (RSNA 2015), Chicago, USA, November 29 - December 4, 2015
Available from: 2017-12-20 Created: 2017-12-20 Last updated: 2017-12-20Bibliographically approved
Alshamari, M., Geijer, M., Norrman, E. & Geijer, H. (2014). Low-dose computed tomography of the lumbar spine: a phantom study on imaging parameters and image quality. Acta Radiologica, 55(7), 824-832
Open this publication in new window or tab >>Low-dose computed tomography of the lumbar spine: a phantom study on imaging parameters and image quality
2014 (English)In: Acta Radiologica, ISSN 0284-1851, E-ISSN 1600-0455, Vol. 55, no 7, p. 824-832Article in journal (Refereed) Published
Abstract [en]

Background: Lumbar spine radiography has limited diagnostic value but low radiation dose compared with computed tomography (CT). The average effective radiation dose from lumbar spine radiography is about 1.1 mSv. Low-dose lumbar spine CT may be an alternative to increase the diagnostic value at low radiation dose, around 1 mSv.

Purpose: To determine the optimal settings for low-dose lumbar spine CT simultaneously aiming for the highest diagnostic image quality possible.

Material and Methods: An ovine lower thoracic and lumbar spine phantom, with all soft tissues around the vertebrae preserved except the skin, was placed in a 20 L plastic container filled with water. The phantom was scanned repeatedly with various technical settings; different tube potential, reference mAs, and with different convolution filters. Five radiologists evaluated the image quality according to a modification of the European guidelines for multislice computed tomography (MSCT) quality criteria for lumbar spine CT 2004. In a visual comparison the different scans were also ranked subjectively according to perceived image quality. Image noise and contrast were measured.

Results: A tube potential of 120 kV with reference mAs 30 and medium or medium smooth convolution filter gave the best image quality at a sub-millisievert dose level, i.e. with an effective dose comparable to that from lumbar spine radiography.

Conclusion: Low-dose lumbar spine CT thus opens a possibility to substitute lumbar spine radiography with CT without obvious increase in radiation dose.

Keywords
conventional radiography; CT; spine; structures; techniques
National Category
Radiology, Nuclear Medicine and Medical Imaging
Research subject
Radiology
Identifiers
urn:nbn:se:oru:diva-38243 (URN)10.1177/0284185113509615 (DOI)000342575300008 ()2-s2.0-84907878366 (Scopus ID)
Available from: 2014-11-03 Created: 2014-10-30 Last updated: 2019-03-26Bibliographically approved
Geijer, H., Norrman, E. & Persliden, J. (2009). Optimizing the tube potential for lumbar spine radiography with a flat-pane digital detector. British Journal of Radiology, 82(973), 62-68
Open this publication in new window or tab >>Optimizing the tube potential for lumbar spine radiography with a flat-pane digital detector
2009 (English)In: British Journal of Radiology, ISSN 0007-1285, E-ISSN 1748-880X, Vol. 82, no 973, p. 62-68Article in journal (Refereed) Published
Abstract [en]

The purpose of this study was to find the optimal settings for lumbar spine radiography with a flat-panel detector. A CDRAD contrast-detail phantom was imaged at various tube potentials, system speeds and filtration settings. Factorial experiments yielded a range of optimized exposure settings, which were submitted to visual grading analysis with images of an Alderson phantom. The first optimized settings involved a system speed increase from 400 to 800. For anteroposterior projection, the optimal tube potential was reduced from the default of 77 kV to 60 kV to give the best image quality without increasing the effective dose, or to 66 kV to give the lowest dose without reducing image quality. For lateral projection, the tube potential was similarly reduced from the default of 90 kV to 70 kV or 77 W. Visual grading analysis confirmed the results, with significantly better image quality when optimizing for image quality. The study thus shows that the tube potential can be reduced as long as the system speed is increased simultaneously. This leads to a lower effective dose and/or increased image quality depending on the settings chosen. The factorial experiments provided a powerful way to evaluate several parameters concomitantly.

National Category
Physical Sciences
Research subject
Physics
Identifiers
urn:nbn:se:oru:diva-13405 (URN)10.1259/bjr/56572915 (DOI)000262680200008 ()
Available from: 2011-01-19 Created: 2011-01-11 Last updated: 2017-12-11Bibliographically approved
Norrman, E. (2007). Optimisation of radiographic imaging by means of factorial experiments. (Doctoral dissertation). Örebro: Örebro universitetsbibliotek
Open this publication in new window or tab >>Optimisation of radiographic imaging by means of factorial experiments
2007 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In the optimisation process of radiographic imaging, factorial designed experiments can be applied. The parameters (factors) are varied together instead of one at a time, making it possible to discover interactions between the factors as well as main influences of them on the result variable. A 2k design implies having k number of factors each one set to two different levels (low and high).

A computer program, CoCIQ, designed to automatically analyse and evaluate test images of a contrast-detail phantom, was evaluated and adjusted to clinical situations using a flat panel detector. The program gives a quantified measurement of image quality by calculating an Image Quality Figure (IQF) for the X-ray image. It was shown that the program produces IQF with small variations. It was also found that there was a strong linear statistical relation between the computerised evaluation and the evaluation performed by human observers.

2k factorial experiments were evaluated by investigating the influence of tube potential, tube loading, focus size and filtration on the result variables IQF, Kerma Area Product (KAP) and effective dose using a flat panel detector. It was found that the result variables were mainly influenced by tube loading, tube potential and filtration. Interactions between tube potential and filtration as well as between tube loading and filtration were observed, too. This work demonstrates that accepted knowledge was reproduced and that the effects of interactions between parameters were revealed.

Extended 2k experiments were then applied at three different optimisation procedures. Two studies were performed using a flat panel detector for lumbar spine radiography. The aim was to find optimal settings for tube potential, system sensitivity and filtration for different sized patients and, in a separate study, to investigate the effect of the image post processing parameters and the possibility for dose reduction by adjusting these. The parameters are ROI (Region Of Interest) density, gamma, detail contrast enhancement, unsharp masking, kernel size and noise compensation.

After determining the optimal settings from these experiments, X-ray images of the lumbar spine of an Alderson phantom were acquired and evaluated in a visual grading analysis (VGA).

The results illustrated that the image quality was maintained at a lower effective dose by operating with a reduced tube potential and increased sensitivity of the X-ray system.

The experiments on image post process parameters revealed their influence on image quality and indicated that image quality could be improved by changing the settings of the process parameters.

Factorial experiments were also performed, using a multislice CT scanner to investigate the possibility for dose reduction at paediatric head examinations. An anthropomorphic phantom simulating a one-year-old child was scanned using different settings of tube potential, tube loading and reconstruction filter.

The study showed that a 25 % reduction of dose was possible with maintained image quality by reducing the tube loading.

Factorial designed experiments provide an effective method to simultaneously predict the influence of various parameters on image quality and radiation dose in the optimisation in diagnostic radiology.

Place, publisher, year, edition, pages
Örebro: Örebro universitetsbibliotek, 2007. p. 87
Series
Örebro Studies in Physics, ISSN 1652-148X ; 3
National Category
Physical Sciences
Research subject
Physics
Identifiers
urn:nbn:se:oru:diva-1731 (URN)978-91-7668-568-6 (ISBN)
Public defence
2008-01-18, HSP 1, Prismahuset, Örebro universitet, Örebro, 10:00
Opponent
Supervisors
Available from: 2007-12-28 Created: 2007-12-18 Last updated: 2017-10-18Bibliographically approved
Norrman, E., Geijer, H. & Persliden, J. (2007). Optimization of image process parameters through factorial experiments using a flat panel detector. Physics in Medicine and Biology, 52(17), 5263-5276
Open this publication in new window or tab >>Optimization of image process parameters through factorial experiments using a flat panel detector
2007 (English)In: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 52, no 17, p. 5263-5276Article in journal (Refereed) Published
Abstract [en]

In the optimization process of lumbar spine examinations, factorial experiments were performed addressing the question of whether the effective dose can be reduced and the image quality maintained by adjusting the image processing parameters. A 2(k)-factorial design was used which is a systematic and effective method of investigating the influence of many parameters on a result variable. Radiographic images of a Contrast Detail phantom were exposed using the default settings of the process parameters for lumbar spine examinations. The image was processed using different settings of the process parameters. The parameters studied were ROI density, gamma, detail contrast enhancement (DCE), noise compensation, unsharp masking and unsharp masking kernel (UMK). The images were computer analysed and an image quality figure (IQF) was calculated and used as a measurement of the image quality. The parameters with the largest influence on image quality were noise compensation, unsharp masking, unsharp masking kernel and detail contrast enhancement. There was an interaction between unsharp masking and kernel indicating that increasing the unsharp masking improved the image quality when combined with a large kernel size. Combined with a small kernel size however the unsharp masking had a deteriorating effect. Performing a factorial experiment gave an overview of how the image quality was influenced by image processing. By adjusting the level of noise compensation, unsharp masking and kernel, the IQF was improved to a 30% lower effective dose.

Place, publisher, year, edition, pages
Bristol: IOP publishing, 2007
Keywords
Quality, Coefficients, Radiography, Reduction, Urography
National Category
Natural Sciences Physical Sciences Medical and Health Sciences Physiology Radiology, Nuclear Medicine and Medical Imaging
Research subject
Physics; Medicine; Radio Physics
Identifiers
urn:nbn:se:oru:diva-2866 (URN)10.1088/0031-9155/52/17/011 (DOI)
Available from: 2007-12-28 Created: 2007-12-28 Last updated: 2018-01-13Bibliographically approved
Norrman, E., Gårdestig, M., Persliden, J. & Geijer, H. (2005). A clinical evaluation of the image quality computer program, CoCIQ. Journal of digital imaging, 18(2), 138-144
Open this publication in new window or tab >>A clinical evaluation of the image quality computer program, CoCIQ
2005 (English)In: Journal of digital imaging, ISSN 0897-1889, E-ISSN 1618-727X, Vol. 18, no 2, p. 138-144Article in journal (Refereed) Published
Abstract [en]

To provide an objective way of measuring image quality, a computer program was designed that automatically analyzes the test images of a contrast-detail (CD) phantom. The program gives a quantified measurement of image quality by calculating an Image Quality Figure (IQF). The aim of this work was to evaluate the program and adjust it to clinical situations in order to find the detectable level where the program gives a reliable figure of the contrast resolution. The program was applied on a large variety of images with lumbar spine and urographic parameters, from very low to very high image qualities. It was shown that the computer program produces IQFs with small variations and there were a strong linear statistical relation between the computerized evaluation and the evaluation performed by human observers (R2 = 0.98). This method offers a fast and easy way of conducting image quality evaluations.

National Category
Physical Sciences
Research subject
Physics
Identifiers
urn:nbn:se:oru:diva-2863 (URN)10.1007/s10278-004-1036-0 (DOI)
Available from: 2007-12-28 Created: 2007-12-28 Last updated: 2017-12-14Bibliographically approved
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