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  • 1.
    Adjeiwaah, Mary
    et al.
    Umea Univ, Dept Radiat Sci, SE-90187 Umea, Sweden..
    Bylund, Mikael
    Umea Univ, Dept Radiat Sci, SE-90187 Umea, Sweden..
    Lundman, Josef A.
    Umea Univ, Dept Radiat Sci, SE-90187 Umea, Sweden..
    Karlsson, Camilla Thellenberg
    Umea Univ, Dept Radiat Sci, SE-90187 Umea, Sweden..
    Jonsson, Joakim H.
    Umea Univ, Dept Radiat Sci, SE-90187 Umea, Sweden..
    Nyholm, Tufve
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Medical Radiation Science. Umea Univ, Dept Radiat Sci, SE-90187 Umea, Sweden.
    Quantifying the Effect of 3T Magnetic Resonance Imaging Residual System Distortions and Patient-Induced Susceptibility Distortions on Radiation Therapy Treatment Planning for Prostate Cancer2018In: International Journal of Radiation Oncology, Biology, Physics, ISSN 0360-3016, E-ISSN 1879-355X, Vol. 100, no 2, p. 317-324Article in journal (Refereed)
    Abstract [en]

    Purpose: To investigate the effect of magnetic resonance system-and patient-induced susceptibility distortions from a 3T scanner on dose distributions for prostate cancers.

    Methods and Materials: Combined displacement fields from the residual system and patient-induced susceptibility distortions were used to distort 17 prostate patient CT images. VMAT dose plans were initially optimized on distorted CT images and the plan parameters transferred to the original patient CT images to calculate a new dose distribution.

    Results: Maximum residual mean distortions of 3.19 mm at a radial distance of 25 cm and maximum mean patient-induced susceptibility shifts of 5.8 mm were found using the lowest bandwidth of 122 Hz per pixel. There was a dose difference of <0.5% between distorted and undistorted treatment plans. The 90% confidence intervals of the mean difference between the dCT and CT treatment plans were all within an equivalence interval of (-0.5, 0.5) for all investigated plan quality measures.

    Conclusions: Patient-induced susceptibility distortions at high field strengths in closed bore magnetic resonance scanners are larger than residual system distortions after using vendor-supplied 3-dimensional correction for the delineated regions studied. However, errors in dose due to disturbed patient outline and shifts caused by patient-induced susceptibility effects are below 0.5%.

  • 2.
    Edmund, Jens M.
    et al.
    Univ Copenhagen, Herlev & Gentofte Hosp, Dept Oncol, Radiotherapy Res Unit, Herlev, Denmark.;Univ Copenhagen, Niels Bohr Inst, Copenhagen, Denmark..
    Nyholm, Tufve
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Medical Radiation Science. Umea Univ, Dept Radiat Sci, SE-90187 Umea, Sweden..
    A review of substitute CT generation for MRI-only radiation therapy2017In: Radiation Oncology, ISSN 1748-717X, E-ISSN 1748-717X, Vol. 12, article id 28Article, review/survey (Refereed)
    Abstract [en]

    Radiotherapy based on magnetic resonance imaging as the sole modality (MRI-only RT) is an area of growing scientific interest due to the increasing use of MRI for both target and normal tissue delineation and the development of MR based delivery systems. One major issue in MRI-only RT is the assignment of electron densities (ED) to MRI scans for dose calculation and a similar need for attenuation correction can be found for hybrid PET/MR systems. The ED assigned MRI scan is here named a substitute CT (sCT). In this review, we report on a collection of typical performance values for a number of main approaches encountered in the literature for sCT generation as compared to CT. A literature search in the Scopus database resulted in 254 papers which were included in this investigation. A final number of 50 contributions which fulfilled all inclusion criteria were categorized according to applied method, MRI sequence/contrast involved, number of subjects included and anatomical site investigated. The latter included brain, torso, prostate and phantoms. The contributions geometric and/or dosimetric performance metrics were also noted. The majority of studies are carried out on the brain for 5-10 patients with PET/MR applications in mind using a voxel based method. T1 weighted images are most commonly applied. The overall dosimetric agreement is in the order of 0.3-2.5%. A strict gamma criterion of 1% and 1mm has a range of passing rates from 68 to 94% while less strict criteria show pass rates > 98%. The mean absolute error (MAE) is between 80 and 200 HU for the brain and around 40 HU for the prostate. The Dice score for bone is between 0.5 and 0.95. The specificity and sensitivity is reported in the upper 80s% for both quantities and correctly classified voxels average around 84%. The review shows that a variety of promising approaches exist that seem clinical acceptable even with standard clinical MRI sequences. A consistent reference frame for method benchmarking is probably necessary to move the field further towards a widespread clinical implementation.

  • 3.
    Fahlström, Markus
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Radiology.
    Blomquist, Erik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Experimental and Clinical Oncology.
    Nyholm, Tufve
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Medical Radiation Science.
    Larsson, Elna-Marie
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Radiology.
    Perfusion Magnetic Resonance Imaging Changes in Normal Appearing Brain Tissue after Radiotherapy in Glioblastoma Patients may Confound Longitudinal Evaluation of Treatment Response2018In: Radiology and Oncology, ISSN 1318-2099, E-ISSN 1581-3207, Vol. 52, no 2, p. 143-151Article in journal (Refereed)
    Abstract [en]

    Background: The aim of this study was assess acute and early delayed radiation-induced changes in normal-appearing brain tissue perfusion as measured with perfusion magnetic resonance imaging (MRI) and the dependence of these changes on the fractionated radiotherapy (FRT) dose level.

    Patients and methods: Seventeen patients with glioma WHO grade III-IV treated with FRT were included in this prospective study, seven were excluded because of inconsistent FRT protocol or missing examinations. Dynamic susceptibility contrast MRI and contrast-enhanced 3D-T1-weighted (3D-T1w) images were acquired prior to and in average (standard deviation): 3.1 (3.3), 34.4 (9.5) and 103.3 (12.9) days after FRT. Pre-FRT 3D-T1w images were segmented into white- and grey matter. Cerebral blood volume (CBV) and cerebral blood flow (CBF) maps were calculated and co-registered patient-wise to pre-FRT 3D-T1w images. Seven radiation dose regions were created for each tissue type: 0-5 Gy, 5-10 Gy, 10-20 Gy, 20-30 Gy, 30-40 Gy, 40-50 Gy and 50-60 Gy. Mean CBV and CBF were calculated in each dose region and normalised (nCBV and nCBF) to the mean CBV and CBF in 0-5 Gy white- and grey matter reference regions, respectively.

    Results: Regional and global nCBV and nCBF in white- and grey matter decreased after FRT, followed by a tendency to recover. The response of nCBV and nCBF was dose-dependent in white matter but not in grey matter.

    Conclusions: Our data suggest that radiation-induced perfusion changes occur in normal-appearing brain tissue after FRT. This can cause an overestimation of relative tumour perfusion using dynamic susceptibility contrast MRI, and can thus confound tumour treatment evaluation.

  • 4.
    Grönlund, Eric
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Medical Radiation Science.
    Almhagen, Erik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Medical Radiation Science.
    Johansson, Silvia
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Experimental and Clinical Oncology. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences.
    Traneus, Erik
    RaySearch Laboratories AB.
    Nyholm, Tufve
    Department of Radiation Sciences, Umeå University, Umeå, Sweden.
    Thellenberg, Camilla
    Department of Radiation Sciences, Umeå University, Umeå, Sweden.
    Ahnesjö, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Medical Radiation Science.
    Robust treatment planning of dose painting for prostate cancer based on ADC-to-Gleason score mapping: what is the potential to increase the tumor control probability?Manuscript (preprint) (Other academic)
    Abstract [en]

    Background and Purpose

    We have in this study evaluated our earlier published dose painting formalism for prostate cancer that is driven by dose-responses of Gleason scores mapped from apparent diffusion coefficient (ADC) image data. The aim of this study is to evaluate the ability to actualize increases of the tumor control probability (TCP) with optimization of “dose painting by numbers” (DPBN) plans in a treatment planning system (TPS) compared to uniform dose treatments for patients with high-risk prostate cancer.

    Material and Methods

    We have evaluated the potential to actualize TCP increases with realistic DPBN plans as compared to uniform dose treatments for a test set of 17 patients diagnosed with high-risk prostate cancer and pre-RT ADC image data. This potential was evaluated through calculating the DPBN efficiency, defined as the ratio of TCP increases for realistic DPBN plans by TCP increases for ideal DPBN prescriptions. Both the ideal DPBN prescriptions and the realistic DPBN plans were optimized with the objective to maximize the TCP for the target prostate volumes (CTVT) while retaining the same average dose as for conventional uniform dose treatments. For the realistic DPBN plan optimization we tested the impact on the TCP by applying different photon energies, different levels of precision of the mapping of ADC data into Gleason score driven dose-responses, and with respect to different levels of iso-center positioning uncertainties through optimizing with robust minimax optimization.

    Results

    The median DPBN efficiency for the most conservative planning scenario optimized with 15MV photons, a low precision ADC-to-Gleason mapping, and a robustness distance of 0.6 cm was 10%, meaning that more than half of the patients had a gain in TCP of at least 10% of the TCP for an ideal DPBN prescription. By using 6MV photons, increasing the precision of the ADC-to-Gleason mapping, and decreasing the robustness distance the median of the DPBN efficiency increased by up to 40%.

    Conclusions

    Optimization of DPBN plans in a TPS can according to our formalism yield TCP increases compared to conventional uniform dose treatments for prostate cancer. These TCP increases are more likely when there is a high precision on the mapping of image data into dose-responses and a high certainty of the tumor position during treatment. These findings motivate further development to ensure accurate and precise mappings of image data into dose-responses and to ensure a high spatial certainty of the tumor position when implementing DPBN in a TPS.

  • 5.
    Gustafsson, Christian
    et al.
    Skane Univ Hosp, Dept Hematol Oncol & Radiat Phys, S-22185 Lund, Sweden.;Lund Univ, Dept Med Radiat Phys, S-20502 Malmo, Sweden..
    Korhonen, Juha
    Helsinki Univ Cent Hosp, Dept Nucl Med, Helsinki 00290, Finland.;Helsinki Univ Cent Hosp, Dept Radiol, Helsinki 00290, Finland.;Helsinki Univ Cent Hosp, Dept Radiat Therapy, Ctr Comprehens Canc, Helsinki 00290, Finland..
    Persson, Emilia
    Skane Univ Hosp, Dept Hematol Oncol & Radiat Phys, S-22185 Lund, Sweden.;Lund Univ, Dept Med Radiat Phys, S-20502 Malmo, Sweden..
    Gunnlaugsson, Adalsteinn
    Skane Univ Hosp, Dept Hematol Oncol & Radiat Phys, S-22185 Lund, Sweden..
    Nyholm, Tufve
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Medical Radiation Science. Umea Univ, Dept Radiat Sci, S-90187 Umea, Sweden.
    Olsson, Lars E.
    Lund Univ, Dept Med Radiat Phys, S-20502 Malmo, Sweden..
    Registration free automatic identification of gold fiducial markers in MRI target delineation images for prostate radiotherapy2017In: Medical physics (Lancaster), ISSN 0094-2405, Vol. 44, no 11, p. 5563-5574Article in journal (Refereed)
    Abstract [en]

    Purpose: The superior soft tissue contrast of magnetic resonance imaging (MRI) compared to computed tomography (CT) has urged the integration of MRI and elimination of CT in radiotherapy treatment (RT) for prostate. An intraprostatic gold fiducial marker (GFM) appears hyperintense on CT. On T2-weighted (T2w) MRI target delineation images, the GFM appear as a small signal void similar to calcifications and post biopsy fibrosis. It can therefore be difficult to identify the markers without CT. Detectability of GFMs can be improved using additional MR images, which are manually registered to target delineation images. This task requires manual labor, and is associated with interoperator differences and image registration errors. The aim of this work was to develop and evaluate an automatic method for identification of GFMs directly in the target delineation images without the need for image registration.

    Methods: T2w images, intended for target delineation, and multiecho gradient echo (MEGRE) images intended for GFM identification, were acquired for prostate cancer patients. Signal voids in the target delineation images were identified as GFM candidates. The GFM appeared as round, symmetric, signal void with increasing area for increasing echo time in the MEGRE images. These image features were exploited for automatic identification of GFMs in a MATLAB model using a patient training dataset (n = 20). The model was validated on an independent patient dataset (n = 40). The distances between the identified GFM in the target delineation images and the GFM in CT images were measured. A human observatory study was conducted to validate the use of MEGRE images.

    Results: The sensitivity, specificity, and accuracy of the automatic method and the observatory study was 84%, 74%, 81% and 98%, 94%, 97%, respectively. The mean absolute difference in the GFM distances for the automatic method and observatory study was 1.28 1.25 mm and 1.14 +/- 1.06 mm, respectively.

    Conclusions: Multiecho gradient echo images were shown to be a feasible and reliable way to perform GFM identification. For clinical practice, visual inspection of the results from the automatic method is needed at the current stage.

  • 6.
    Kuess, Peter
    et al.
    Med Univ Vienna, Dept Radiat Oncol, Div Med Radiat Phys, Vienna, Austria; Christian Doppler Lab Med Radiat Res Radiat Oncol, Vienna, Austria.
    Andrzejewski, Piotr
    Med Univ Vienna, Dept Radiat Oncol, Div Med Radiat Phys, Vienna, Austria; Christian Doppler Lab Med Radiat Res Radiat Oncol, Vienna, Austria.
    Nilsson, David
    Umeå Univ, Dept Chem, Computat Life Sci Cluster CliC, Umeå, Sweden.
    Georg, Petra
    Christian Doppler Lab Med Radiat Res Radiat Oncol, Vienna, Austria; EBG MedAustron GmbH, Wiener Neustadt, Austria.
    Knoth, Johannes
    Med Univ Vienna, Dept Radiat Oncol, Div Med Radiat Phys, Vienna, Austria.
    Susani, Martin
    Med Univ Vienna, Clin Inst Pathol, Vienna, Austria.
    Trygg, Johan
    Umeå Univ, Dept Chem, Computat Life Sci Cluster CliC, Umeå, Sweden.
    Helbich, Thomas H.
    Christian Doppler Lab Med Radiat Res Radiat Oncol, Vienna, Austria; Med Univ Vienna, Dept Biomed Imaging & Image Guided Therapy, Vienna, Austria.
    Polanec, Stephan H.
    Christian Doppler Lab Med Radiat Res Radiat Oncol, Vienna, Austria; Med Univ Vienna, Dept Biomed Imaging & Image Guided Therapy, Vienna, Austria.
    Georg, Dietmar
    Med Univ Vienna, Dept Radiat Oncol, Div Med Radiat Phys, Vienna, Austria; Christian Doppler Lab Med Radiat Res Radiat Oncol, Vienna, Austria.
    Nyholm, Tufve
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Medical Radiation Science. Umeå Univ, Dept Radiat Sci, Radiat Phys, Umeå, Sweden.
    Association between pathology and texture features of multi parametric MRI of the prostate2017In: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 62, no 19, p. 7833-7854Article in journal (Refereed)
    Abstract [en]

    The role of multi-parametric (mp)MRI in the diagnosis and treatment of prostate cancer has increased considerably. An alternative to visual inspection of mpMRI is the evaluation using histogram-based (first order statistics) parameters and textural features (second order statistics). The aims of the present work were to investigate the relationship between benign and malignant sub-volumes of the prostate and textures obtained from mpMR images. The performance of tumor prediction was investigated based on the combination of histogram-based and textural parameters. Subsequently, the relative importance of mpMR images was assessed and the benefit of additional imaging analyzed. Finally, sub-structures based on the PI-RADS classification were investigated as potential regions to automatically detect maligned lesions. Twenty-five patients who received mpMRI prior to radical prostatectomy were included in the study. The imaging protocol included T2, DWI, and DCE. Delineation of tumor regions was performed based on pathological information. First and second order statistics were derived from each structure and for all image modalities. The resulting data were processed with multivariate analysis, using PCA (principal component analysis) and OPLS-DA (orthogonal partial least squares discriminant analysis) for separation of malignant and healthy tissue. PCA showed a clear difference between tumor and healthy regions in the peripheral zone for all investigated images. The predictive ability of the OPLS-DA models increased for all image modalities when first and second order statistics were combined. The predictive value reached a plateau after adding ADC and T2, and did not increase further with the addition of other image information. The present study indicates a distinct difference in the signatures between malign and benign prostate tissue. This is an absolute prerequisite for automatic tumor segmentation, but only the first step in that direction. For the specific identified signature, DCE did not add complementary information to T2 and ADC maps.

  • 7.
    Lundman, Josef A.
    et al.
    Umea Univ, Dept Radiat Sci, Umea, Sweden..
    Johansson, Adam
    Umea Univ, Dept Radiat Sci, Umea, Sweden.;Univ Michigan, Dept Radiat Oncol, Ann Arbor, MI 48109 USA..
    Olofsson, Jorgen
    Umea Univ, Dept Radiat Sci, Umea, Sweden..
    Axelsson, Jan
    Umea Univ, Dept Radiat Sci, Umea, Sweden..
    Larsson, Anne
    Umea Univ, Dept Radiat Sci, Umea, Sweden..
    Nyholm, Tufve
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Medical Radiation Science. Umea Univ, Dept Radiat Sci, Umea, Sweden..
    Effect of gradient field nonlinearity distortions in MRI-based attenuation maps for PET reconstruction2017In: Physica medica (Testo stampato), ISSN 1120-1797, E-ISSN 1724-191X, Vol. 35, p. 1-6Article in journal (Refereed)
    Abstract [en]

    Purpose: Attenuation correction is a requirement for quantification of the activity distribution in PET. The need to base attenuation correction on MRI instead of CT has arisen with the introduction of integrated PET/MRI systems. The aim was to describe the effect of residual gradient field nonlinearity distortions on PET attenuation correction. Methods: MRI distortions caused by gradient field nonlinearity were simulated in CT images used for attenuation correction in PET reconstructions. The simulations yielded radial distortion of up to +/- 2: 3 mm at 15 cm from the scanner isocentre for distortion corrected images. The mean radial distortion of uncorrected images were 6.3 mm at the same distance. Reconstructions of PET data were performed using the distortion corrected images as well as the images where no correction had been applied. Results: The mean relative difference in reconstructed PET uptake intensity due to incomplete distortion correction was less than +/- 5%. The magnitude of this difference varied between patients and the size of the distortions remaining after distortion correction. Conclusions: Radial distortions of 2 mm at 15 cm radius from the scanner isocentre lead to PET attenuation correction errors smaller than 5%. Keeping the gradient field nonlinearity distortions below this limit can be a reasonable goal for MRI systems used for attenuation correction in PET for quantification purposes. A higher geometrical accuracy may, however, be warranted for quantification of peripheral lesions. These distortions can, e.g., be controlled at acceptance testing and subsequent quality assurance intervals.

  • 8.
    Nyholm, Tufve
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Medical Radiation Science. Umea Univ, Dept Radiat Sci, S-90187 Umea, Sweden..
    Olsson, Caroline
    Gothenburg Univ, Sahlgrenska Acad, Inst Clin Sci, Dept Radiat Phys, Gothenburg, Sweden.;Western Sweden Healthcare Reg, Reg Canc Ctr West, Gothenburg, Sweden..
    Agrup, Mans
    Linkoping Univ Hosp, Dept Oncol, Linkoping, Sweden..
    Bjork, Peter
    Malar Hosp, Dept Phys & Biomed Engn, Eskilstuna, Sweden..
    Bjork-Eriksson, Thomas
    Sahlgrens Univ Hosp, Dept Oncol, Gothenburg, Sweden..
    Gagliardi, Giovanna
    Karolinska Univ Hosp, Dept Med Phys, Stockholm, Sweden..
    Grinaker, Hanne
    Swedish Radiat Safety Author, Lund, Sweden..
    Gunnlaugsson, Adalsteinn
    Lund Univ, Skane Univ Hosp, Dept Oncol & Radiat Phys, S-22100 Lund, Sweden..
    Gustafsson, Anders
    Cureos AB, Uppsala, Sweden..
    Gustafsson, Magnus
    Sahlgrens Univ Hosp, Dept Phys & Biomed Engn, Gothenburg, Sweden..
    Johansson, Bengt
    Orebro Univ Hosp, Dept Oncol, Orebro, Sweden.;Univ Orebro, Orebro, Sweden..
    Johnsson, Stefan
    Kalmar Cty Hosp, Dept Radiat Phys, Kalmar, Sweden..
    Karlsson, Magnus
    Umea Univ, Dept Radiat Sci, S-90187 Umea, Sweden..
    Kristensen, Ingrid
    Lund Univ, Skane Univ Hosp, Dept Oncol & Radiat Phys, S-22100 Lund, Sweden..
    Nilsson, Per
    Lund Univ, Skane Univ Hosp, Dept Oncol & Radiat Phys, S-22100 Lund, Sweden..
    Nystrom, Leif
    Umea Univ, Dept Radiat Sci, S-90187 Umea, Sweden..
    Onjukka, Eva
    Karolinska Univ Hosp, Dept Med Phys, Stockholm, Sweden..
    Reizenstein, Johan
    Univ Orebro, Orebro, Sweden..
    Skonevik, Johan
    Umea Univ, Dept Radiat Sci, S-90187 Umea, Sweden.;Orebro Univ Hosp, Dept Oncol, Orebro, Sweden..
    Soderstrom, Karin
    Umea Univ, Dept Radiat Sci, S-90187 Umea, Sweden..
    Valdman, Alexander
    Karolinska Univ Hosp, Dept Oncol, Stockholm, Sweden..
    Zackrisson, Bjorn
    Umea Univ, Dept Radiat Sci, S-90187 Umea, Sweden..
    Montelius, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Medical Radiation Science.
    A national approach for automated collection of standardized and population-based radiation therapy data in Sweden2016In: Radiotherapy and Oncology, ISSN 0167-8140, E-ISSN 1879-0887, Vol. 119, no 2, p. 344-350Article in journal (Refereed)
    Abstract [en]

    Purpose: To develop an infrastructure for structured and automated collection of interoperable radiation therapy (RT) data into a national clinical quality registry. Materials and methods: The present study was initiated in 2012 with the participation of seven of the 15 hospital departments delivering RT in Sweden. A national RT nomenclature and a database for structured unified storage of RT data at each site (Medical Information Quality Archive, MIQA) have been developed. Aggregated data from the MIQA databases are sent to a national RT registry located on the same IT platform (INCA) as the national clinical cancer registries. Results: The suggested naming convention has to date been integrated into the clinical workflow at 12 of 15 sites, and MIQA is installed at six of these. Involvement of the remaining 3/15 RT departments is ongoing, and they are expected to be part of the infrastructure by 2016. RT data collection from ARIA (R), Mosaiq (R), Eclipse (TM), and Oncentra (R) is supported. Manual curation of RT-structure information is needed for approximately 10% of target volumes, but rarely for normal tissue structures, demonstrating a good compliance to the RT nomenclature. Aggregated dose/volume descriptors are calculated based on the information in MIQA and sent to INCA using a dedicated service (MIQA2INCA). Correct linkage of data for each patient to the clinical cancer registries on the INCA platform is assured by the unique Swedish personal identity number. Conclusions: An infrastructure for structured and automated prospective collection of syntactically inter operable RT data into a national clinical quality registry for RT data is under implementation. Future developments include adapting MIQA to other treatment modalities (e.g. proton therapy and brachytherapy) and finding strategies to harmonize structure delineations. How the RT registry should comply with domain-specific ontologies such as the Radiation Oncology Ontology (ROO) is under discussion.

  • 9.
    Olausson, Kristina
    et al.
    Umeå universitet, Onkologi.
    Holst Hansson, Annette
    Department of Care Sciences, Faculty of Health and Society, Malmö, Sweden.
    Zackrisson, Björn
    Umeå universitet, Onkologi.
    Edvardsson, David
    Umeå universitet, Institutionen för omvårdnad.
    Östlund, Ulrika
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Medicinska och farmaceutiska vetenskapsområdet, centrumbildningar mm, Centre for Research and Development, Gävleborg. Linnaeus University.
    Nyholm, Tufve
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Medical Radiation Science. Umeå universitet, Radiofysik.
    Development and psychometric testing of an instrument to measure the patient’s experience of external radiotherapy: The Radiotherapy Experience Questionnaire (RTEQ)2017In: Technical Innovations & Patient Support in Radiation Oncology, ISSN 2405-6324, Vol. 3-4, p. 7-12Article in journal (Refereed)
    Abstract [en]

    Background

    The patient’s perception of external radiotherapy (RT) procedures and equipment is important to evaluate as a complement to endpoints such as treatment outcome and reproducibility. There is a lack of a proper, psychometrically robust instrument to evaluate the patient’s comfort and experience of the external RT procedure. Hence, this study aimed to develop and test an instrument to measure the patient’s experience during external RT.

    Material and Methods

    A preliminary 34-item questionnaire was generated from research literature, expert consultations and patient interviews, and it was distributed to patients (n = 825) at 8 RT units in Sweden. The answers were subjected to item analysis and reduction by using exploratory factor analysis. The reliability of the final questionnaire was evaluated using Cronbach’s alpha. Mean scale scores were compared across gender, length of RT and treatment area.

    Results

    Most items were highly skewed towards positive responses. Scree plot analyses of the 34-item correlation matrix identified six underlying themes explaining 68% of the total variance. After item reduction, the 6 themes explained 73% of the variance in a 23-item questionnaire. Cronbach’s alpha was satisfactory for all themes (between 0.79 and 0.9). Significant differences between treatment areas were found for two scales: situational unease and situational repose.

    Conclusion

    The RT Experience Questionnaire is a tentatively valid and reliable instrument to measure how patients experience the external RT session process and the environment in the treatment room.

  • 10.
    Persson, Emilia
    et al.
    Skane Univ Hosp, Dept Hematol Oncol & Radiat Phys, Klinikgatan 5, S-22185 Lund, Sweden.;Lund Univ, Dept Med Phys, Malmo, Sweden..
    Gustafsson, Christian
    Skane Univ Hosp, Dept Hematol Oncol & Radiat Phys, Klinikgatan 5, S-22185 Lund, Sweden.;Lund Univ, Dept Med Phys, Malmo, Sweden..
    Nordström, Fredrik
    Sahlgrens Univ Hosp, Dept Med Phys & Biomed Engn, Gothenburg, Sweden..
    Sohlin, Maja
    Sahlgrens Univ Hosp, Dept Med Phys & Biomed Engn, Gothenburg, Sweden..
    Gunnlaugsson, Adalsteinn
    Skane Univ Hosp, Dept Hematol Oncol & Radiat Phys, Klinikgatan 5, S-22185 Lund, Sweden..
    Petruson, Karin
    Sahlgrens Univ Hosp, Dept Oncol, Gothenburg, Sweden..
    Rintelä, Niina
    Karolinska Univ Hosp, Med Radiat Phys & Nucl Med, Stockholm, Sweden..
    Hed, Kristoffer
    Karolinska Univ Hosp, Med Radiat Phys & Nucl Med, Stockholm, Sweden..
    Blomqvist, Lennart
    Karolinska Univ Hosp, Dept Diagnost Radiol, Stockholm, Sweden.;Umea Univ, Dept Radiat Sci, Umea, Sweden.;Karolinska Inst, Dept Mol Med & Surg, Stockholm, Sweden..
    Zackrisson, Björn
    Umea Univ, Dept Radiat Sci, Umea, Sweden..
    Nyholm, Tufve
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Medical Radiation Science. Umea Univ, Dept Radiat Sci, Umea, Sweden.
    Olsson, Lars E.
    Lund Univ, Dept Med Phys, Malmo, Sweden..
    Siversson, Carl
    Spectron Med AB, Helsingborg, Sweden..
    Jonsson, Joakim
    Umea Univ, Dept Radiat Sci, Umea, Sweden..
    MR-OPERA: A Multicenter/Multivendor Validation of Magnetic Resonance Imaging-Only Prostate Treatment Planning Using Synthetic Computed Tomography Images2017In: International Journal of Radiation Oncology, Biology, Physics, ISSN 0360-3016, E-ISSN 1879-355X, Vol. 99, no 3, p. 692-700Article in journal (Refereed)
    Abstract [en]

    Purpose: To validate the dosimetric accuracy and clinical robustness of a commercially available software for magnetic resonance (MR) to synthetic computed tomography (sCT) conversion, in an MR imaginge-only workflow for 170 prostate cancer patients.

    Methods and Materials: The 4 participating centers had MriPlanner (Spectronic Medical), an atlas-based sCT generation software, installed as a cloud-based service. A T2-weighted MR sequence, covering the body contour, was added to the clinical protocol. The MR images were sent from the MR scanner workstation to theMriPlanner platform. The sCT was automatically returned to the treatment planning system. Four MR scanners and 2 magnetic field strengths were included in the study. For each patient, a CT-treatment plan was created and approved according to clinical practice. The sCT was rigidly registered to the CT, and the clinical treatment plan was recalculated on the sCT. The dose distributions from the CT plan and the sCT plan were compared according to a set of dose-volume histogram parameters and gamma evaluation. Treatment techniques included volumetric modulated arc therapy, intensity modulated radiation therapy, and conventional treatment using 2 treatment planning systems and different dose calculation algorithms.

    Results: The overall (multicenter/multivendor) mean dose differences between sCT and CT dose distributions were below 0.3% for all evaluated organs and targets. Gamma evaluation showed a mean pass rate of 99.12% (0.63%, 1 SD) in the complete body volume and 99.97% (0.13%, 1 SD) in the planning target volume using a 2%/ 2-mm global gamma criteria.

    Conclusions: Results of the study show that the sCT conversion method can be used clinically, with minimal differences between sCT and CT dose distributions for target and relevant organs at risk. The small differences seen are consistent between centers, indicating that an MR imagingeonly workflow using MriPlanner is robust for a variety of field strengths, vendors, and treatment techniques.

  • 11.
    Sandgren, Kristina
    et al.
    Umea Univ, Dept Radiat Sci, S-90185 Umea, Sweden.
    Westerlinck, Philippe
    Iridium Canc Network, Dept Radiat Oncol, Antwerp, Belgium.
    Jonsson, Joakim H.
    Umea Univ, Dept Radiat Sci, S-90185 Umea, Sweden.
    Blomqvist, Lennart
    Umea Univ, Dept Radiat Sci, S-90185 Umea, Sweden;Karolinska Inst, Dept Mol Med & Surg, Stockholm, Sweden.
    Karlsson, Camilla Thellenberg
    Umea Univ, Dept Radiat Sci, S-90185 Umea, Sweden.
    Nyholm, Tufve
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Medical Radiation Science. Umea Univ, Dept Radiat Sci, S-90185 Umea, Sweden.
    Dirix, Piet
    Iridium Canc Network, Dept Radiat Oncol, Antwerp, Belgium;Ctr Oncol Res CORE, Dept Mol Imaging Pathol Radiotherapy & Oncol MIPR, Antwerp, Belgium.
    Imaging for the Detection of Locoregional Recurrences in Biochemical Progression After Radical Prostatectomy: A Systematic Review2019In: EUROPEAN UROLOGY FOCUS, ISSN 2405-4569, Vol. 5, no 4, p. 550-560Article, review/survey (Refereed)
    Abstract [en]

    Context

    Local and regional recurrence after radical prostatectomy (RP) can be treated using salvage radiotherapy (SRT). If the recurrence can be delineated on diagnostic imaging, this could allow for increasingly individualized SRT.

    Objective

    This systematic review aimed at evaluating the evidence regarding the usefulness of positron emission tomography (PET) and magnetic resonance imaging (MRI) in identifying local and regional recurrences, with the aim to further individualize the SRT treatment.

    Evidence acquisition

    A systematic PubMed/Medline search was conducted in December 2015. Studies included were imaging studies of post-RP patients focusing on local and/or regional recurrence where sensitivity and specificity of MRI or PET were the primary end points. Only studies using biopsy, other histological analysis, and/or treatment follow-up as reference standard were included. Quality Assessment of Diagnostic Accuracy Studies-2 was used to score the study quality. Twenty-five articles were deemed of sufficient quality and included in the review.

    Evidence synthesis

    [11C]Acetate had the highest pooled sensitivity (92%), while [11C]choline and [18F]choline had pooled sensitivities of 71% and 84%, respectively. The PET tracer with highest pooled specificity was [11C]choline (86%). Regarding MRI, MR spectroscopy combined with dynamic contrast enhanced (DCE) MRI showed the highest pooled sensitivity (89%). High pooled sensitivities were also seen using multiparametric MRI (84%), diffusion-weighted MRI combined with T2-weigthed (T2w) imaging (82%), and DCE MRI combined with T2w imaging (82%). These also showed high pooled specificities (85%, 89%, and 92%, respectively).

    Conclusions

    Both MRI and PET have adequate sensitivity and specificity for the detection of prostate cancer recurrences post-RP. Multiparametric MRI, using diffusion-weighted and/or DCE imaging, and the choline-labeled tracers showed high pooled sensitivity and specificity, although their ranges were broad.

    Patient summary

    After reviewing imaging studies of recurrent prostate cancer after prostatectomy, we concluded that choline positron emission tomography and diffusion-weighted magnetic resonance imaging can be proposed as the current standard, with high sensitivity and specificity.

  • 12.
    Wiesinger, Florian
    et al.
    GE Healthcare, Freisinger Landstr 50, D-85748 Munich, Germany.
    Bylund, Mikael
    Umea Univ, Umea, Sweden.
    Yang, Jaewon
    UCSF, San Francisco, CA USA.
    Kaushik, Sandeep
    GE Global Res, Bangalore, Karnataka, India.
    Shanbhag, Dattesh
    GE Global Res, Bangalore, Karnataka, India.
    Ahn, Sangtae
    GE Global Res, Niskayuna, NY USA.
    Jonsson, Joakim H.
    Umea Univ, Umea, Sweden.
    Lundman, Josef A.
    Umea Univ, Umea, Sweden.
    Hope, Thomas
    UCSF, San Francisco, CA USA.
    Nyholm, Tufve
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Medical Radiation Science. Umea Univ, Umea, Sweden.
    Larson, Peder
    UCSF, San Francisco, CA USA.
    Cozzini, Cristina
    GE Healthcare, Freisinger Landstr 50, D-85748 Munich, Germany.
    Zero TE-based pseudo-CT image conversion in the head and its application in PET/MR attenuation correction and MR-guided radiation therapy planning2018In: Magnetic Resonance in Medicine, ISSN 0740-3194, E-ISSN 1522-2594, Vol. 80, no 4, p. 1440-1451Article in journal (Refereed)
    Abstract [en]

    Purpose: To describe a method for converting Zero TE (ZTE) MR images into Xray attenuation information in the form of pseudo-CT images and demonstrate its performance for (1) attenuation correction (AC) in PET/MR and (2) dose planning in MR-guided radiation therapy planning (RTP). Methods: Proton density-weighted ZTE images were acquired as input for MRbased pseudo-CT conversion, providing (1) efficient capture of short-lived bone signals, (2) flat soft-tissue contrast, and (3) fast and robust 3D MR imaging. After bias correction and normalization, the images were segmented into bone, soft-tissue, and air by means of thresholding and morphological refinements. Fixed Hounsfield replacement values were assigned for air (-1000 HU) and soft-tissue (142 HU), whereas continuous linear mapping was used for bone. Results: The obtained ZTE-derived pseudo-CT images accurately resembled the true CT images (i. e., Dice coefficient for bone overlap of 0.73 +/- 0.08 and mean absolute error of 123 +/- 25 HU evaluated over the whole head, including errors from residual registration mismatches in the neck and mouth regions). The linear bone mapping accounted for bone density variations. Averaged across five patients, ZTE-based AC demonstrated a PET error of -0.04 +/- 1.68% relative to CT-based AC. Similarly, for RTP assessed in eight patients, the absolute dose difference over the target volume was found to be 0.23 +/- 0.42%. Conclusion: The described method enables MR to pseudo-CT image conversion for the head in an accurate, robust, and fast manner without relying on anatomical prior knowledge. Potential applications include PET/MR-AC, and MR-guided RTP.

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