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Carlsson Tedgren, ÅsaORCID iD iconorcid.org/0000-0002-4549-8303
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Publications (10 of 52) Show all publications
Georgi, P., Carlsson Tedgren, Å., Persson, L. & Johansen, J. G. (2024). Determination of intrinsic energy dependence of point-like inorganic scintillation detector in brachytherapy. Medical Physics, 51(7), 5059-5069
Open this publication in new window or tab >>Determination of intrinsic energy dependence of point-like inorganic scintillation detector in brachytherapy
2024 (English)In: Medical Physics, ISSN 0094-2405, E-ISSN 2473-4209, Vol. 51, no 7, p. 5059-5069Article in journal (Refereed) Published
Abstract [en]

Background: Inorganic scintillation detectors (ISDs) are promising for in vivo dosimetry in brachytherapy (BT). ISDs have fast response, providing time resolved dose rate information, and high sensitivity, attributed to high atomic numbers. However, the conversion of the detector signal to absorbed dose-to-water is highly dependent on the energy spectrum of the incident radiation. This dependence is comprised of absorbed dose energy dependence, obtainable with Monte Carlo (MC) simulation, and the absorbed dose-to-signal conversion efficiency or intrinsic energy dependence requiring measurements. Studies have indicated negligible intrinsic energy dependence of ZnSe:O-based ISDs in Ir-192 BT. A full characterization has not been performed earlier.Purpose: This study characterizes the intrinsic energy dependence of ZnSe:O-based ISDs for kV X-ray radiation qualities, with energies relevant for BT.Methods: Three point-like ISDs made from fiber-coupled cuboid ZnSe:O-based scintillators were calibrated at the Swedish National Metrology Laboratory for ionizing radiation. The calibration was done in terms of air kerma free-in-air, K-air, in 13 X-ray radiation qualities, Q, from 25 to 300 kVp (CCRI 25-250 kV and ISO 4037 N-series), and in terms of absorbed dose to water, D-w, in a Co-60 beam, Q(0).The mean absorbed dose to the ISDs, relative to K-air and D-w, were obtained with the MC code TOPAS (Geant4) using X-ray spectra obtained with SpekPy software and laboratory filtration data and a generic Co-60 source.The intrinsic energy dependence was determined as a function of effective photon energy, E-eff, (relative to Co-60).The angular dependence of the ISD signal was measured in a 25 kVp (0.20 mm Al HVL) and 135 kVp beam (0.48 mm Cu HVL), by rotating the ISDs 180 degrees around the fiber's longitudinal axis (perpendicular to the beam). A full 360 degrees was not performed due to setup limitations. The impact of detector design was quantified with MC simulation.ResultsAbove 30 keV E-eff the intrinsic energy dependence varied with less than 5 +/- 4% from unity for all detectors (with the uncertainty expressed as the mean of all expanded measurement uncertainties for individual E-eff above 30 keV, k = 2). Below 30 keV, it decreased with up to 17% and inter-detector variations of 13% were observed, likely due to differences in detector geometry not captured by the simulations using nominal geometry. In the 25 kVp radiation quality, the ISD signal varied with 24% over a similar to 45 degrees rotation. For 135 kVp, the corresponding variation was below 3%. Assuming a 0.05 mm thicker layer of reflective paint around the sensitive volume changed the absorbed dose with 6.3% at the lowest E-eff, and with less than 2% at higher energies.ConclusionThe study suggests that the ISDs have an intrinsic energy dependence relative to Co-60 lower than 5 +/- 4% in radiation qualities with E-eff > 30 keV. Therefore, they could in principle be calibrated in a Co-60 beam quality and transferred to such radiation qualities with correction factors determined only by the absorbed dose energy dependence obtained from MC simulations. This encourages exploration of the ISDs' applications in intensity modulated BT with Yb-169 or other novel intermediate energy isotopes.

Place, publisher, year, edition, pages
WILEY, 2024
Keywords
energy dependence; inorganic scintillator; kV radiotherapy dosimetry
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:liu:diva-200504 (URN)10.1002/mp.16904 (DOI)001139412100001 ()38197459 (PubMedID)2-s2.0-85181748886 (Scopus ID)
Note

Funding Agencies|Novo Nordisk Fonden; Swedish Cancer Society [211788 PJ]; [NNF19OC0058756]

Available from: 2024-01-30 Created: 2024-01-30 Last updated: 2025-03-27Bibliographically approved
De Brabandere, M., Placidi, E., Siebert, F.-A. -., Slocker Escarpa, A., Tagliaferri, L., Andrássy, M., . . . Carlsson Tedgren, Å. (2024). GEC-ESTRO survey of 106Ru eye applicator practice for ocular melanoma – Physicist survey. Radiotherapy and Oncology, 193, Article ID 110114.
Open this publication in new window or tab >>GEC-ESTRO survey of 106Ru eye applicator practice for ocular melanoma – Physicist survey
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2024 (English)In: Radiotherapy and Oncology, ISSN 0167-8140, E-ISSN 1879-0887, Vol. 193, article id 110114Article in journal (Refereed) Published
Abstract [en]

Aim: 106Ru eye plaque brachytherapy (BT, interventional radiotherapy) is an eye-preserving treatment for uveal melanoma performed in about 100 clinics worldwide. Despite this relatively low number, there is a considerable variation in clinical practice. In 2022, the BRAPHYQS and Head & Neck and Skin GEC-ESTRO working groups conducted a survey to map the current clinical practice. The survey consisted of a physicist and a physician part. This paper describes the physicist results. However, three physician questions with overlapping interest are included here as well. Materials and Methods: The survey questions pertained to commissioning and quality control (QC) of the plaques, treatment planning, radiobiological correction, as well as more general questions on practice improvement. The questions overlapping with the physician survey were related to dose prescription and margins. Results: Sixty-five physicist responses were included. A majority of the centres do not perform an independent measurement of the absorbed dose at reference depth, percentage depth dose (PDD) and off-axis data. A lack of calibration services and suitable equipment are the main reasons. About one third of the centres indicated that they do image based treatment planning. The use of margins and dose prescription showed a large variability, despite the availability of guidelines [1]. Many respondents expressed a strong wish for improvement in a wide range of aspects of clinical practice. Conclusion: The physics survey showed a wide variability regarding quality control of the 106Ru sources and treatment planning practice. © 2024 Elsevier B.V.

Place, publisher, year, edition, pages
Elsevier, 2024
Keywords
Brachytherapy, Eye plaque, Ocular melanoma, Humans, Melanoma, Radiotherapy Dosage, Radiotherapy Planning, Computer-Assisted, Surveys and Questionnaires, ruthenium 106, Article, calibration, cancer radiotherapy, clinical practice, dosimetry, eye melanoma, health survey, human, medical physicist, physician, practice guideline, prescribing practice, prescription, quality control, radiation measurement, radiobiology, radioisotope therapy, surgical margin, total quality management, treatment planning, procedures, questionnaire
National Category
Radiology and Medical Imaging
Identifiers
urn:nbn:se:liu:diva-211868 (URN)10.1016/j.radonc.2024.110114 (DOI)001184433200001 ()38309583 (PubMedID)2-s2.0-85184860365 (Scopus ID)
Available from: 2025-02-27 Created: 2025-02-27 Last updated: 2025-02-27
Morén, B., Antaki, M., Famulari, G., Morcos, M., Larsson, T., Enger, S. A. & Carlsson Tedgren, Å. (2023). Dosimetric impact of a robust optimization approach to mitigate effects from rotational uncertainty in prostate intensity‐modulated brachytherapy. Medical physics (Lancaster), 50(2), 1029-1043
Open this publication in new window or tab >>Dosimetric impact of a robust optimization approach to mitigate effects from rotational uncertainty in prostate intensity‐modulated brachytherapy
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2023 (English)In: Medical physics (Lancaster), ISSN 0094-2405, Vol. 50, no 2, p. 1029-1043Article in journal (Refereed) Published
Abstract [en]

BackgroundIntensity-modulated brachytherapy (IMBT) is an emerging technology for cancer treatment, in which radiation sources are shielded to shape the dose distribution. The rotatable shields provide an additional degree of freedom, but also introduce an additional, directional, type of uncertainty, compared to conventional high-dose-rate brachytherapy (HDR BT). PurposeWe propose and evaluate a robust optimization approach to mitigate the effects of rotational uncertainty in the shields with respect to planning criteria. MethodsA previously suggested prototype for platinum-shielded prostate Yb-169-based dynamic IMBT is considered. We study a retrospective patient data set (anatomical contours and catheter placement) from two clinics, consisting of six patients that had previously undergone conventional Ir-192 HDR BT treatment. The Monte Carlo-based treatment planning software RapidBrachyMCTPS is used for dose calculations. In our computational experiments, we investigate systematic rotational shield errors of +/- 10 degrees and +/- 20 degrees, and the same systematic error is applied to all dwell positions in each scenario. This gives us three scenarios, one nominal and two with errors. The robust optimization approach finds a compromise between the average and worst-case scenario outcomes. ResultsWe compare dose plans obtained from standard models and their robust counterparts. With dwell times obtained from a linear penalty model (LPM), for 10 degrees errors, the dose to urethra (D0.1cc) and rectum (D0.1cc and D1cc) increase with up to 5% and 7%, respectively, in the worst-case scenario, while with the robust counterpart, the corresponding increases were 3% and 3%. For all patients and all evaluated criteria, the worst-case scenario outcome with the robust approach had lower deviation compared to the standard model, without compromising target coverage. We also evaluated shield errors up to 20 degrees and while the deviations increased to a large extent with the standard models, the robust models were capable of handling even such large errors. ConclusionsWe conclude that robust optimization can be used to mitigate the effects from rotational uncertainty and to ensure the treatment plan quality of IMBT.

Place, publisher, year, edition, pages
WILEY, 2023
Keywords
high dose-rate brachytherapy; inverse treatment planning; prostate IMBT; robust optimization
National Category
Other Mathematics Cancer and Oncology
Identifiers
urn:nbn:se:liu:diva-190890 (URN)10.1002/mp.16134 (DOI)000905521500001 ()36478226 (PubMedID)2-s2.0-85145268798 (Scopus ID)
Funder
Swedish Research Council, VR‐NT 2019‐05416Swedish Cancer Society, CAN 2017/1029Swedish Cancer Society, Pj 211788
Note

Funding: Vetenskapsradet [VR-NT 2019-05416]; Cancerfonden [CAN 2017/1029]; Canada Research Chairs [252135]; Collaborative health research projects [523394-18]

Available from: 2023-01-20 Created: 2023-01-20 Last updated: 2024-05-02Bibliographically approved
Magnusson, M., Alm Carlsson, G., Sandborg, M., Carlsson Tedgren, Å. & Malusek, A. (2023). On the Choice of Base Materials for Alvarez–Macovski and DIRA Dual-energy Reconstruction Algorithms in CT. In: Scott Hsieh, Krzysztof (Kris) Iniewski (Ed.), Photon Counting Computed Tomography: Clinical Applications, Image Reconstruction and Material Discrimination (pp. 153-175). Cham: Springer
Open this publication in new window or tab >>On the Choice of Base Materials for Alvarez–Macovski and DIRA Dual-energy Reconstruction Algorithms in CT
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2023 (English)In: Photon Counting Computed Tomography: Clinical Applications, Image Reconstruction and Material Discrimination / [ed] Scott Hsieh, Krzysztof (Kris) Iniewski, Cham: Springer , 2023, p. 153-175Chapter in book (Refereed)
Abstract [en]

The choice of the material base to which the material decomposition is performed in dual-energy computed tomography may affect the quality of reconstructed images. Resulting inaccuracies may lower their diagnostic value, or if the data are used for radiation treatment planning, the accuracy of such plans. The aim of this work is to investigate how the commonly used (water, bone) (WB), (water, iodine) (WI), and (approximate photoelectric effect, Compton scattering) (PC) doublets affect the reconstructed linear attenuation coefficient in the case of the Alvarez–Macovski (AM) method. The performance of this method is also compared to the performance of the dual-energy iterative reconstruction algorithm DIRA. In both cases, the study is performed using simulations.

The results show that the PC and WB doublets accurately predicted the linear attenuation coefficient (LAC) values for human tissues and elements with Z = 1, …, 20, in the 20–150 keV range, though there was a small (<5% discrepancy in the 20–35 keV range. The WI doublet did not represent the tissues as well as PC and WB; the largest discrepancies (>50% in some cases) were in the 20–40 keV range.

LACs reconstructed with the AM and DIRA followed this trend. AM produced artifacts when iodine was present in the phantom together with human tissues since AM can only work with one doublet at a time. It was shown that these artifacts could be avoided with DIRA using different doublets at different spatial positions, i.e., WB for soft and bone tissue and WI for the iodine solution.

Place, publisher, year, edition, pages
Cham: Springer, 2023
National Category
Medical Engineering
Identifiers
urn:nbn:se:liu:diva-194309 (URN)10.1007/978-3-031-26062-9_8 (DOI)2-s2.0-85172101197 (Scopus ID)9783031260629 (ISBN)9783031260612 (ISBN)
Note

Funding text: This work was supported by Cancerfonden [CAN 2017/1029, CAN 2018/622]; ALF Grants Region Östergötland [LiO-602731]; Patientsäkerhetsforskning Region Östergötland [LiO-724181]; and Vetenskapsrådet [VR-NT 2016-05033].

Available from: 2023-06-01 Created: 2023-06-01 Last updated: 2025-02-21Bibliographically approved
Morén, B., Bokrantz, R., Dohlmar, F., Andersson, B., Setterquist, E., Larsson, T. & Carlsson Tedgren, Å. (2023). Technical note: evaluation of a spatial optimization model for prostate high dose‐rate brachytherapy in a clinical treatment planning system. Medical physics (Lancaster), 50(2), 688-693
Open this publication in new window or tab >>Technical note: evaluation of a spatial optimization model for prostate high dose‐rate brachytherapy in a clinical treatment planning system
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2023 (English)In: Medical physics (Lancaster), ISSN 0094-2405, Vol. 50, no 2, p. 688-693Article in journal (Refereed) Published
Abstract [en]

BackgroundSpatial properties of a dose distribution, such as volumes of contiguous hot spots, are of clinical importance in treatment planning for high dose-rate brachytherapy (HDR BT). We have in an earlier study developed an optimization model that reduces the prevalence of contiguous hot spots by modifying a tentative treatment plan. PurposeThe aim of this study is to incorporate the correction of hot spots in a standard inverse planning workflow and to validate the integrated model in a clinical treatment planning system. The spatial function is included in the objective function for the inverse planning, as opposed to in the previous study where it was applied as a separate post-processing step. Our aim is to demonstrate that fine-adjustments of dose distributions, which are often performed manually in todays clinical practice, can be automated. MethodsA spatial optimization function was introduced in the treatment planning system RayStation (RaySearch Laboratories AB, Stockholm, Sweden) via a research interface. A series of 10 consecutive prostate patients treated with HDR BT was retrospectively replanned with and without the spatial function. ResultsOptimization with the spatial function decreased the volume of the largest contiguous hot spot by on average 31%, compared to if the function was not included. The volume receiving at least 200% of the prescription dose decreased by on average 11%. Target coverage, measured as the fractions of the clinical target volume (CTV) and the planning target volume (PTV) receiving at least the prescription dose, was virtually unchanged (less than a percent change for both metrics). Organs-at-risk received comparable or slightly decreased doses if the spatial function was included in the optimization model. ConclusionsOptimization of spatial properties such as the volume of contiguous hot spots can be integrated in a standard inverse planning workflow for brachytherapy, and need not be conducted as a separate post-processing step.

Place, publisher, year, edition, pages
WILEY, 2023
Keywords
high dose-rate brachytherapy; hot spots; spatial properties; treatment planning
National Category
Other Mathematics Cancer and Oncology
Identifiers
urn:nbn:se:liu:diva-190889 (URN)10.1002/mp.16166 (DOI)000910964700001 ()36542400 (PubMedID)2-s2.0-85146175361 (Scopus ID)
Funder
Swedish Cancer Society, CAN 2017/1029Swedish Cancer Society, Pj 211788Swedish Research Council, VR-NT 2019-05416
Note

Funding: Vetenskapsradet (VR) [VR-NT 2019-155 05416]; Cancerfonden (Swedish Cancer Society) [CAN 2017/1029, Pj 211788]

Available from: 2023-01-20 Created: 2023-01-20 Last updated: 2024-05-17Bibliographically approved
Magnusson, M., Sandborg, M., Alm Carlsson, G., Henriksson, L., Carlsson Tedgren, Å. & Malusek, A. (2021). ACCURACY OF CT NUMBERS OBTAINED BY DIRA AND MONOENERGETIC PLUS ALGORITHMS IN DUAL-ENERGY COMPUTED TOMOGRAPHY. Radiation Protection Dosimetry, 195(3-4), 212-217
Open this publication in new window or tab >>ACCURACY OF CT NUMBERS OBTAINED BY DIRA AND MONOENERGETIC PLUS ALGORITHMS IN DUAL-ENERGY COMPUTED TOMOGRAPHY
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2021 (English)In: Radiation Protection Dosimetry, ISSN 0144-8420, E-ISSN 1742-3406, Vol. 195, no 3-4, p. 212-217Article in journal (Refereed) Published
Abstract [en]

Dual-energy computed tomography (CT) can be used in radiotherapy treatment planning for the calculation of absorbed dose distributions. The aim of this work is to evaluate whether there is room for improvement in the accuracy of the Monoenergetic Plus algorithm by Siemens Healthineers. A Siemens SOMATOM Force scanner was used to scan a cylindrical polymethyl methacrylate phantom with four rod-inserts made of different materials. Images were reconstructed using ADMIRE and processed with Monoenergetic Plus. The resulting CT numbers were compared with tabulated values and values simulated by the proof-of-a-concept algorithm DIRA developed by the authors. Both the Monoenergetic Plus and DIRA algorithms performed well; the accuracy of attenuation coefficients was better than about ±1% at the energy of 70 keV. Compared with DIRA, the worse performance of Monoenergetic Plus was caused by its (i) two-material decomposition to iodine and water and (ii) imperfect suppression of the beam hardening artifact in ADMIRE.

Place, publisher, year, edition, pages
Oxford University Press, 2021
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:liu:diva-180414 (URN)10.1093/rpd/ncab108 (DOI)000711245400013 ()34265847 (PubMedID)
Note

Funding: CancerfondenSwedish Cancer Society [CAN 2017/1029, CAN 2018/622]; Swedish state government [LiO-602731]; Swedish county councils, the ALF-agreement [LiO-602731]; Patientsakerhetsforskning Region Ostergotland [LiO-724181]; VetenskapsradetSwedish Research Council [VR-NT 2016-05033]

Available from: 2021-10-19 Created: 2021-10-19 Last updated: 2022-05-25Bibliographically approved
Kaveckyte, V., Carlsson Tedgren, Å. & Varea, J. M. (2021). Impact of the I-value of diamond on the energy deposition in different beam qualities. Physics in Medicine and Biology, 66(12), Article ID 125004.
Open this publication in new window or tab >>Impact of the I-value of diamond on the energy deposition in different beam qualities
2021 (English)In: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 66, no 12, article id 125004Article in journal (Refereed) Published
Abstract [en]

Diamond detectors are increasingly employed in dosimetry. Their response has been investigated by means of Monte Carlo (MC) methods, but there is no consensus on what mass density ρ, mean excitation energy I and number of conduction electrons per atom nce to use in the simulations. The ambiguity occurs due to its seeming similarity with graphite (both are carbon allotropes). Contrary to diamond, graphite has been well-characterized. Except for the difference in ρ between crystalline graphite (2.265 g cm-3) and diamond (3.515 g cm-3), their dielectric properties are assumed to be identical. This is incorrect, and the two materials should be distinguished: (ρ = 2.265 g cm-3, I = 81.0 eV, nce = 1) for graphite and (ρ = 3.515 g cm-3, I = 88.5 eV, nce = 0) for diamond. Simulations done with the MC code PENELOPE show that the energy imparted in diamond decreases by up to 1% with respect to 'pseudo-diamond' (ρ = 3.515 g cm-3, I = 81.0 eV, nce = 0) depending on the beam quality and cavity thickness. The energy imparted changed the most in cavities that are small compared with the range of electrons. The difference in the density-effect term relative to graphite was the smallest for diamond owing to an interplay effect that ρ, I and nce have on this term, in contrast to pseudo-diamond media when either ρ or I alone were adjusted. The study also presents a parameterized density-effect correction function for diamond that may be used by MC codes like EGSnrc. The ESTAR program assumes that nce = 2 for all carbon-based materials, hence it delivers an erroneous density-effect correction term for graphite and diamond. Despite the small changes of the energy imparted in diamond simulated with two different I values and expected close-to-negligible deviation from the published small-field output correction data, it is important to pay attention to material properties and model the medium faithfully.

Place, publisher, year, edition, pages
Institute of Physics (IOP), 2021
Keywords
Diamond, graphite, mass electronic stopping power, density-effect correction, Monte Carlo simulation
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:liu:diva-176110 (URN)10.1088/1361-6560/ac028f (DOI)000658482300001 ()34014176 (PubMedID)
Note

Funding: Swedish Cancer Society (Cancerfonden)Swedish Cancer Society [CAN 2017/1029, CAN 2018/622]; Spanish Ministerio de Ciencia, Innovacion y Universidades [PGC2018-096788-B-I00]

Available from: 2021-06-07 Created: 2021-06-07 Last updated: 2021-12-17Bibliographically approved
Malusek, A., Henriksson, L., Eriksson, P., Dahlström, N., Carlsson Tedgren, Å. & Uvdal, K. (2021). On The Possibility To Resolve Gadolinium- And Cerium-Based Contrast Agents From Their CT Numbers In Dual-Energy Computed Tomography. Paper presented at Optimisation in X-ray and Molecular Imaging 2020, Gothenburg, Sweden, 22-24 June 2020.. Radiation Protection Dosimetry, 195(3-4), 225-231
Open this publication in new window or tab >>On The Possibility To Resolve Gadolinium- And Cerium-Based Contrast Agents From Their CT Numbers In Dual-Energy Computed Tomography
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2021 (English)In: Radiation Protection Dosimetry, ISSN 0144-8420, E-ISSN 1742-3406, Vol. 195, no 3-4, p. 225-231Article in journal (Refereed) Published
Abstract [en]

Cerium oxide nanoparticles with integrated gadolinium have been proved to be useful as contrast agents in magnetic resonance imaging. Of question is their performance in dual-energy computed tomography. The aims of this work are to determine (1) the relation between the computed tomography number and the concentration of the I, Gd or Ce contrast agent and (2) under what conditions it is possible to resolve the type of contrast agent. Hounsfield values of iodoacetic acid, gadolinium acetate and cerium acetate dissolved in water at molar concentrations of 10, 50 and 100 mM were measured in a water phantom using the Siemens SOMATOM Definition Force scanner; gadolinium- and cerium acetate were used as substitutes for the gadolinium-integrated cerium oxide nanoparticles. The relation between the molar concentration of the I, Gd or Ce contrast agent and the Hounsfield value was linear. Concentrations had to be sufficiently high to resolve the contrast agents.

Place, publisher, year, edition, pages
Oxford University Press, 2021
Keywords
Public Health, Environmental and Occupational Health, Radiology Nuclear Medicine and imaging, General Medicine, Radiation
National Category
Health Sciences
Identifiers
urn:nbn:se:liu:diva-180195 (URN)10.1093/rpd/ncab078 (DOI)000711245400015 ()34109383 (PubMedID)
Conference
Optimisation in X-ray and Molecular Imaging 2020, Gothenburg, Sweden, 22-24 June 2020.
Funder
Swedish Research Council, VR-NT 2016-05033
Note

Funding: VetenskapsradetSwedish Research Council [VR-NT 2016-05033]

Available from: 2021-10-11 Created: 2021-10-11 Last updated: 2022-05-25Bibliographically approved
Magnusson, M., Alm Carlsson, G., Sandborg, M., Carlsson Tedgren, Å. & Malusek, A. (2021). Optimal Selection of Base Materials for Accurate Dual-Energy Computed Tomography: Comparison Between the Alvarez–Macovski Method and DIRA. Paper presented at Optimisation in X-ray and Molecular Imaging 2020, Gothenburg, Sweden, 22-24 June 2020.. Radiation Protection Dosimetry, 195(3-4), 218-224
Open this publication in new window or tab >>Optimal Selection of Base Materials for Accurate Dual-Energy Computed Tomography: Comparison Between the Alvarez–Macovski Method and DIRA
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2021 (English)In: Radiation Protection Dosimetry, ISSN 0144-8420, E-ISSN 1742-3406, Vol. 195, no 3-4, p. 218-224Article in journal (Refereed) Published
Abstract [en]

The choice of the material base to which the material decomposition is performed in dual-energy computed tomography may affect the quality of reconstructed images. The aim of this work is to investigate how the commonly used bases (water, bone), (water, iodine) and (photoelectric effect, Compton scattering) affect the reconstructed linear attenuation coefficient in the case of the Alvarez–Macovski method. The performance of this method is also compared with the performance of the Dual-energy Iterative Reconstruction Algorithm (DIRA). In both cases, the study is performed using simulations. The results show that the Alvarez–Macovski method produced artefacts when iodine was present in the phantom together with human tissues since this method can only work with one doublet. It was shown that these artefacts could be avoided with DIRA using the (water, bone) doublet for tissues and the (water, iodine) doublet for the iodine solution.

Place, publisher, year, edition, pages
Oxford University Press, 2021
Keywords
Public Health, Environmental and Occupational Health, Radiology Nuclear Medicine and imaging, General Medicine, Radiation, Radiological and Ultrasound Technology
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:liu:diva-180182 (URN)10.1093/rpd/ncab097 (DOI)000711245400014 ()34240219 (PubMedID)
Conference
Optimisation in X-ray and Molecular Imaging 2020, Gothenburg, Sweden, 22-24 June 2020.
Funder
Swedish Cancer Society, CAN 2017/1029Region Östergötland, LiO-602731Swedish Cancer Society, CAN 2018/622Region Östergötland, LiO-724181Swedish Research Council, VR-NT 2016-05033
Note

Funding: CancerfondenSwedish Cancer Society [CAN 2017/1029, CAN 2018/622]; ALF Grants Region Ostergotland [LiO-602731]; Patientsakerhetsforskning Region Ostergotland [LiO-724181]; VetenskapsradetSwedish Research Council [VR-NT 2016-05033]

Available from: 2021-10-11 Created: 2021-10-11 Last updated: 2021-11-15Bibliographically approved
Morén, B., Larsson, T. & Carlsson Tedgren, Å. (2021). Optimization in treatment planning of high dose‐rate brachytherapy: Review and analysis of mathematical models. Medical Physics, 48(5), 2057-2082
Open this publication in new window or tab >>Optimization in treatment planning of high dose‐rate brachytherapy: Review and analysis of mathematical models
2021 (English)In: Medical Physics, ISSN 2473-4209, Vol. 48, no 5, p. 2057-2082Article, review/survey (Refereed) Published
Abstract [en]

Treatment planning in high dose‐rate brachytherapy has traditionally been conducted with manual forward planning, but inverse planning is today increasingly used in clinical practice. There is a large variety of proposed optimization models and algorithms to model and solve the treatment planning problem. Two major parts of inverse treatment planning for which mathematical optimization can be used are the decisions about catheter placement and dwell time distributions. Both these problems as well as integrated approaches are included in this review. The proposed models include linear penalty models, dose–volume models, mean‐tail dose models, quadratic penalty models, radiobiological models, and multiobjective models. The aim of this survey is twofold: (i) to give a broad overview over mathematical optimization models used for treatment planning of brachytherapy and (ii) to provide mathematical analyses and comparisons between models. New technologies for brachytherapy treatments and methods for treatment planning are also discussed. Of particular interest for future research is a thorough comparison between optimization models and algorithms on the same dataset, and clinical validation of proposed optimization approaches with respect to patient outcome.

Place, publisher, year, edition, pages
Wiley-Blackwell Publishing Inc., 2021
National Category
Cancer and Oncology Radiology, Nuclear Medicine and Medical Imaging Other Mathematics
Identifiers
urn:nbn:se:liu:diva-174984 (URN)10.1002/mp.14762 (DOI)000635672500001 ()
Funder
Swedish Research Council, VR‐NT 2015‐04543Swedish Cancer Society, CAN 2017/1029Swedish Cancer Society, CAN 2018/622
Note

Funding: Swedish Research CouncilSwedish Research CouncilEuropean Commission [VR-NT 2015-04543]; Swedish Cancer SocietySwedish Cancer Society [CAN 2017/1029, CAN 2018/622]

Available from: 2021-04-12 Created: 2021-04-12 Last updated: 2022-05-24Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0002-4549-8303

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