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Nilsson Althen, Jonas
Alternative names
Publications (10 of 13) Show all publications
Kataria, B., Nilsson Althen, J., Smedby, Ö., Persson, A., Sökjer, H. & Sandborg, M. (2019). Image quality and pathology assessment in CT Urography: when is the low-dose seriessufficient?. BMC Medical Imaging, 19, Article ID 64.
Open this publication in new window or tab >>Image quality and pathology assessment in CT Urography: when is the low-dose seriessufficient?
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2019 (English)In: BMC Medical Imaging, ISSN 1471-2342, E-ISSN 1471-2342, Vol. 19, article id 64Article in journal (Refereed) Published
Abstract [en]

Background

Our aim was to compare CT images from native, nephrographic and excretory phases using image quality criteria as well as the detection of positive pathological findings in CT Urography, to explore if the radiation burden to the younger group of patients or patients with negative outcomes can be reduced.

Methods

This is a retrospective study of 40 patients who underwent a CT Urography examination on a 192-slice dual source scanner. Image quality was assessed for four specific renal image criteria from the European guidelines, together with pathological assessment in three categories: renal, other abdominal, and incidental findings without clinical significance. Each phase was assessed individually by three radiologists with varying experience using a graded scale. Certainty scores were derived based on the graded assessments. Statistical analysis was performed using visual grading regression (VGR). The limit for significance was set at p = 0.05.

Results

For visual reproduction of the renal parenchyma and renal arteries, the image quality was judged better for the nephrogram phase (p < 0.001), whereas renal pelvis/calyces and proximal ureters were better reproduced in the excretory phase compared to the native phase (p < 0.001). Similarly, significantly higher certainty scores were obtained in the nephrogram phase for renal parenchyma and renal arteries, but in the excretory phase for renal pelvis/calyxes and proximal ureters. Assessment of pathology in the three categories showed no statistically significant differences between the three phases. Certainty scores for assessment of pathology, however, showed a significantly higher certainty for renal pathology when comparing the native phase to nephrogram and excretory phase and a significantly higher score for nephrographic phase but only for incidental findings.

Conclusion

Visualisation of renal anatomy was as expected with each post-contrast phase showing favourable scores compared to the native phase. No statistically significant differences in the assessment of pathology were found between the three phases. The low-dose CT (LDCT) seems to be sufficient in differentiating between normal and pathological examinations. To reduce the radiation burden in certain patient groups, the LDCT could be considered a suitable alternative as a first line imaging method. However, radiologists should be aware of its limitations.

Place, publisher, year, edition, pages
BioMed Central, 2019
Keywords
Computed tomography, Urography, Low-dose, Optimization, Image quality, Dose
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:liu:diva-159965 (URN)10.1186/s12880-019-0363-z (DOI)000480486200001 ()31399078 (PubMedID)2-s2.0-85070460822 (Scopus ID)
Projects
Visual grading evaluation of reconstruction methods and dose optimisation in abdominal Computed Tomography
Funder
Region Östergötland, LIO-620341Linköpings universitet, LIO-697941
Available from: 2019-08-30 Created: 2019-08-30 Last updated: 2019-09-04Bibliographically approved
Kataria, B., Sandborg, M. & Nilsson Althen, J. (2016). IMPLICATIONS OF PATIENT CENTRING ON ORGAN DOSE IN COMPUTED TOMOGRAPHY. Radiation Protection Dosimetry, 169(1-4), 130-135
Open this publication in new window or tab >>IMPLICATIONS OF PATIENT CENTRING ON ORGAN DOSE IN COMPUTED TOMOGRAPHY
2016 (English)In: Radiation Protection Dosimetry, ISSN 0144-8420, E-ISSN 1742-3406, Vol. 169, no 1-4, p. 130-135Article in journal (Refereed) Published
Abstract [en]

Automatic exposure control (AEC) in computed tomography (CT) facilitates optimisation of dose absorbed by the patient. The use of AEC requires appropriate ‘patient centring’ within the gantry, since positioning the patient off-centre may affect both image quality and absorbed dose. The aim of this experimental study was to measure the variation in organ and abdominal surface dose during CTexaminations of the head, neck/thorax and abdomen. The dose was compared at the isocenter with two off-centre positions—ventral and dorsal to the isocenter. Measurements were made with an anthropomorphic adult phantom and thermoluminescent dosemeters. Organs and surfaces for ventral regions received lesser dose (5.6–39.0 %) than the isocenter when the phantom was positioned 13 cm off-centre. Similarly, organ and surface doses for dorsal regions were reduced by 5.0–21.0 % at 25 cm off-centre. Therefore, correct vertical positioning of the patient at the gantry isocenter is important to maintain optimal imaging conditions.

Place, publisher, year, edition, pages
Oxford University Press, 2016
Keywords
computed tomography, organ dose
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:liu:diva-125340 (URN)10.1093/rpd/ncv527 (DOI)000383492100020 ()26743256 (PubMedID)
Available from: 2016-02-19 Created: 2016-02-19 Last updated: 2019-09-01
Nilsson Althén, J. & Sandborg, M. (2016). VERIFICATION OF INDICATED SKIN ENTRANCE AIR KERMA FORCARDIAC X-RAY-GUIDED INTERVENTION USING GAFCHROMIC FILM. Radiation Protection Dosimetry, 169(1-4), 245-248
Open this publication in new window or tab >>VERIFICATION OF INDICATED SKIN ENTRANCE AIR KERMA FORCARDIAC X-RAY-GUIDED INTERVENTION USING GAFCHROMIC FILM
2016 (English)In: Radiation Protection Dosimetry, ISSN 0144-8420, E-ISSN 1742-3406, Vol. 169, no 1-4, p. 245-248Article in journal (Refereed) Published
Abstract [en]

The aim of this work was to verify the indicated maximum entrance surface air kerma (ESAK) using a GE Innova IGS 520 imaging system during cardiac interventional procedures. Gafchromic XR RV3 films were used for the patient measurements to monitor the maximum ESAK. The films were scanned and calibrated to measure maximum ESAK. Thermoluminescent dosemeters were used to measure the backscatter factor from an anthropomorphic thorax phantom. The measured backscatter factor, 1.53, was in good agreement with Monte Carlo simulations but higher than the one used by the imaging system, 1.20. The median of the ratio between indicated maximum ESAK and measured maximum ESAKwas 0.68. In this work, the indicated maximum ESAK by the imaging system’s dose map model underestimates the measured maximum ESAK by 32 %. The threshold ESAK for follow-up procedures for patient with skin dose in excess of 2 Gy will be reduced to 1.4 Gy.

Place, publisher, year, edition, pages
Oxford University Press, 2016
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:liu:diva-122967 (URN)10.1093/rpd/ncv460 (DOI)000383492100037 ()26541185 (PubMedID)
Note

Funding agencies: County Council of Ostergotland

Available from: 2015-12-01 Created: 2015-12-01 Last updated: 2017-12-01
Sandborg, M., Nilsson Althén, J., Pettersson, H. & Rossitti, S. (2012). Patient Organ Radiation Doses During Treatment for Aneurysmal Subarachnoid Hemorrhage. Clinical neuroradiology, 22(4), 315-325
Open this publication in new window or tab >>Patient Organ Radiation Doses During Treatment for Aneurysmal Subarachnoid Hemorrhage
2012 (English)In: Clinical neuroradiology, ISSN 1869-1447, Vol. 22, no 4, p. 315-325Article in journal (Refereed) Published
Abstract [en]

PURPOSE: The aim of this retrospective study was to estimate risk organ doses and to estimate radiation risks during the imaging work-up and treatment for aneurysmal subarachnoid hemorrhage (SAH). METHODS: The imaging procedures comprised computed tomography and digital subtraction angiography studies for diagnosis or endovascular interventional procedures in 50 consecutive patients. Equivalent organ doses (H(T)) to skin, brain, eye lens, salivary glands, thyroid and oral mucosa were measured using thermoluminescence dosimeters in an anthropomorphic head phantom. Picture archiving and communication system (PACS) and radiological information system (RIS) records were analyzed and the frequency of each imaging procedure was recorded as well as the registered individual kerma-length product (P(KL)) and the kerma-area product (P(KA)). The doses were computed by multiplying the recorded P(KL) and P(KA) values by the conversion coefficients H(T)/P(KL) and H(T)/P(KA) from the head phantom. RESULTS: The mean fluoroscopy time, P(KL) and P(KA) were 38 min, 7269 mGy cm and 286 Gy cm(2), respectively. The estimated mean equivalent doses were as follows: skin 2.51 Sv, brain 0.92 Sv, eye lens 0.43 Sv and salivary glands 0.23 Sv. Maximum organ doses were 2.3-3.5 times higher than the mean. Interventional procedures contributed 66 % to skin dose, 55 % to brain dose and 25 % to eye lens dose. Of the patients with an estimated skin dose exceeding 6 Sv, only 1 developed temporary epilation. CONCLUSION: The risk for radiation-induced cancer for SAH patients is low (2-3 cases per 1,000 patients, of which 90 % are expected to be benign types) compared with the risk of tissue reactions on the head such as skin erythema and epilation (1 temporary epilation per 50 patients).

Place, publisher, year, edition, pages
Springer, 2012
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-78917 (URN)10.1007/s00062-012-0147-0 (DOI)000311500500004 ()22576966 (PubMedID)
Available from: 2012-06-25 Created: 2012-06-25 Last updated: 2014-02-27
Sandborg, M., Rossitti, S., Pettersson, H. & Nilsson Althen, J. (2011). Patient organ radiation doses during treatment for aneurismal subarachnoid haemorrhage. Paper presented at Nordiska sällskapet för strålskydd, NSFS Conference, 22-25 August, 2011, Reykjavik , Island.
Open this publication in new window or tab >>Patient organ radiation doses during treatment for aneurismal subarachnoid haemorrhage
2011 (English)Conference paper, Published paper (Other academic)
National Category
Radiology, Nuclear Medicine and Medical Imaging Neurology
Identifiers
urn:nbn:se:liu:diva-76168 (URN)
Conference
Nordiska sällskapet för strålskydd, NSFS Conference, 22-25 August, 2011, Reykjavik , Island
Available from: 2012-03-29 Created: 2012-03-29 Last updated: 2013-09-03
Sandborg, M., Nilsson Althen, J. & Gustafsson, A. (2010). Efficient quality assurance in radiology and Nuclear Medicine. Paper presented at World Federation Congress in Nuclear Meicine and Biology, Cape Town,.
Open this publication in new window or tab >>Efficient quality assurance in radiology and Nuclear Medicine
2010 (English)Conference paper, Oral presentation with published abstract (Other academic)
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:liu:diva-91086 (URN)
Conference
World Federation Congress in Nuclear Meicine and Biology, Cape Town,
Available from: 2013-04-15 Created: 2013-04-15 Last updated: 2013-09-03
Sandborg, M., Nilsson Althen, J. & Gustafsson, A. (2010). EFFICIENT QUALITY ASSURANCE PROGRAMS IN RADIOLOGY AND NUCLEAR MEDICINE IN ÖSTERGÖTLAND, SWEDEN. Radiation Protection Dosimetry, 139(1-3), 410-417
Open this publication in new window or tab >>EFFICIENT QUALITY ASSURANCE PROGRAMS IN RADIOLOGY AND NUCLEAR MEDICINE IN ÖSTERGÖTLAND, SWEDEN
2010 (English)In: Radiation Protection Dosimetry, ISSN 0144-8420, E-ISSN 1742-3406, Vol. 139, no 1-3, p. 410-417Article in journal (Refereed) Published
Abstract [en]

Owners of imaging modalities using ionising radiation should have a documented quality assurance (QA) program, as well as methods to justify new radiological procedures to ensure safe operation and adequate clinical image quality. This includes having a system for correcting divergences, written imaging protocols, assessment of patient and staff absorbed doses and a documented education and training program. In this work, how some aspects on QA have been implemented in the County of Östergötland in Sweden, and efforts to standardise and automate the process as an integrated part of the radiology and nuclear medicine QA programs were reviewed. Some key performance parameters have been identified by a Swedish task group of medical physicists to give guidance on selecting relevant QA methods. These include low-contrast resolution, image homogeneity, automatic exposure control, calibration of air kerma-area product metres and patient–dose data registration in the radiological information system, as well as the quality of reading stations and of the transfer of images to the picture archive and communication system. IT-driven methods to automatically assess patient doses and other data on all examinations are being developed and evaluated as well as routines to assess clinical image quality by use of European quality criteria. By assessing both patient absorbed doses and clinical image quality on a routine basis, the medical physicists in our region aim to be able to spend more time on imaging optimisation and less time on periodic testing of the technical performance of the equipment, particularly on aspects that show very few divergences. The role of the Medical Physics Expert is rapidly developing towards a person doing advanced data-analysis and giving scientific support rather than one performing mainly routine periodic measurements. It is concluded that both the European Council directive and the rapid development towards more complex diagnostic imaging systems and procedures support this changing role of the medical physics professional.

Place, publisher, year, edition, pages
Oxford University Press, 2010
Keywords
quality assurance, quality controll
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:liu:diva-56400 (URN)10.1093/rpd/ncq065 (DOI)000277738200078 ()
Note

This is a pre-copy-editing, author-produced PDF of an article accepted for publication in Radiation Protection Dosimetry following peer review. The definitive publisher-authenticated version: Michael Sandborg, Jonas Nilsson Althen and Agneta Gustafsson, Efficient Quality Assurance Programs In Radiology And Nuclear Medicine In Östergötland, Sweden, 2010, Radiation Protection Dosimetry, (139), 1-3, 410-417. is available online at: http://dx.doi.org/10.1093/rpd/ncq065 Copyright: Oxford University Press http://www.oxfordjournals.org/

Available from: 2010-05-10 Created: 2010-05-10 Last updated: 2017-12-12
Helmrot, E., Pettersson, H., Sandborg, M. & Nilsson Althen, J. (2007). Estimation of the dose to the unborn child at diagnostic X-ray examinations based on data registrerad in RIS/PACS. European Radiology, 17(1), 205-209
Open this publication in new window or tab >>Estimation of the dose to the unborn child at diagnostic X-ray examinations based on data registrerad in RIS/PACS
2007 (English)In: European Radiology, ISSN 0938-7994, E-ISSN 1432-1084, Vol. 17, no 1, p. 205-209Article in journal (Refereed) Published
Abstract [en]

The aim of this work was to determine mean absorbed doses to the unborn child in common conventional X-ray and computed tomography (CT) examinations and to find an approach for estimating foetal dose based on data registered in the Radiological Information System/Picture Archive and Communication System (RIS/PACS). The kerma-area product (KAP) and CT dose index (CTDIvol) in common examinations were registered using a human-shaped female dosimetry phantom. Foetal doses, Df, were measured using thermoluminescent dosimeters placed inside the phantom and compared with calculated values. Measured foetal doses were given in relation to the KAP and the CTDIvol values, respectively. Conversion factor Df/KAP varies between 0.01 and 3.8 mGy/Gycm2, depending on primary beam position, foetus age and beam quality (tube voltage and filtration). Conversion factors Df/CTDIvol are in the range 0.02 – 1.2 mGy/mGy, in which the foetus is outside or within the primary beam. We conclude that dose conversion factors based on KAP or CTDIvol values automatically generated by the RIS/PACS system can be used for rapid estimations of foetal dose for common examination techniques.

Keywords
Pregnancy - Radiation - Foetal dose - Radiological protection - Patient doses
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-21427 (URN)10.1007/s00330-006-0286-2 (DOI)000243396700024 ()
Available from: 2009-10-01 Created: 2009-10-01 Last updated: 2017-12-13
Nilsson, J. (2005). Automatic tube-current modulation in CT - A comparison between different solutions. Radiation Protection Dosimetry, 114(1-3), 308-312
Open this publication in new window or tab >>Automatic tube-current modulation in CT - A comparison between different solutions
2005 (English)In: Radiation Protection Dosimetry, ISSN 0144-8420, E-ISSN 1742-3406, Vol. 114, no 1-3, p. 308-312Article in journal (Refereed) Published
Abstract [en]

In this study, tube-current modulation systems on two different CT equipments have been evaluated: Care Dose from Siemens and Auto mA from GE Medical Systems. Care Dose modulates the tube current in the xy-plane during rotation whereas Auto mA modulates the tube current in the z-direction. xy-Plane modulation was investigated by using an elliptic Poly-methylmethacrylate phantom and a CTDI-ion chamber. To investigate modulation in the z-direction, an anthropomorphic dosimetry phantom (Atom) was used. Tests performed with and without tube-current modulation were compared with respect to absorbed dose and image quality. In the anthropomorphic phantom measurements, the dose savings were 15% using Care Dose and the photon starvation artefacts were negligible. Using Auto mA the absorbed dose depends on the chosen noise level. Image noise becomes more constant throughout the patient but photon starvation artefacts remain. We conclude that the two tube-current modulation techniques show different dose advantages and image quality artefacts. © The Author 2005. Published by Oxford University Press. All rights reserved.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-28735 (URN)10.1093/rpd/nch501 (DOI)13907 (Local ID)13907 (Archive number)13907 (OAI)
Available from: 2009-10-09 Created: 2009-10-09 Last updated: 2017-12-13
Nilsson Althén, J. (2005). Automatic tube-current modulation in CT-A comparison between different solutions. In: Optimisation Strategies in medical x-ray imaging,2004 (pp. 308). Oxford: Oxford University Press
Open this publication in new window or tab >>Automatic tube-current modulation in CT-A comparison between different solutions
2005 (English)In: Optimisation Strategies in medical x-ray imaging,2004, Oxford: Oxford University Press , 2005, p. 308-Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
Oxford: Oxford University Press, 2005
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-32624 (URN)18541 (Local ID)18541 (Archive number)18541 (OAI)
Available from: 2009-10-09 Created: 2009-10-09
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