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  • 1.
    Andersson, Karin M.
    et al.
    Örebro University, School of Medical Sciences.
    Nowik, P.
    Department of Medical Physics, Karolinska University Hospital, Stockholm, Sweden.
    Persliden, Jan
    Örebro University, School of Health and Medical Sciences, Örebro University, Sweden. Department of Medical Physics, Faculty of Health and Medical Sciences, Örebro University, Örebro, Sweden.
    Thunberg, Per
    Department of Medical Physics, Örebro University Hospital, Örebro, Sweden.
    Norrman, Eva
    Örebro University, School of Health and Medical Sciences, Örebro University, Sweden. Department of Medical Physics, Faculty of Health and Medical Sciences, Örebro University, Örebro, Sweden.
    Metal artefact reduction in CT imaging of hip prostheses-an evaluation of commercial techniques provided by four vendors2015In: British Journal of Radiology, ISSN 0007-1285, E-ISSN 1748-880X, Vol. 88, no 1052, article id 20140473Article in journal (Refereed)
    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.

  • 2. Geijer, Håkan
    et al.
    Norrman, Eva
    Örebro University, Department of Natural Sciences.
    Persliden, Jan
    Optimizing the tube potential for lumbar spine radiography with a flat-pane digital detector2009In: British Journal of Radiology, ISSN 0007-1285, E-ISSN 1748-880X, Vol. 82, no 973, p. 62-68Article in journal (Refereed)
    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.

  • 3. Jansson, Margareta
    et al.
    Geijer, Håkan
    Örebro University, Department of Clinical Medicine.
    Persliden, Jan
    Örebro University, Department of Clinical Medicine.
    Andersson, Torbjörn
    Örebro University, Department of Clinical Medicine.
    Reducing dose in urography while maintaining image quality - a comparison of storage phosphor plates and a flat-panel detector2006In: European Radiology, ISSN 0938-7994, E-ISSN 1432-1084, Vol. 16, no 1, p. 221-226Article in journal (Refereed)
    Abstract [en]

    The introduction of new flat-panel detector technology often forces us to accept too high dose levels as proposed by the manufacturers. We need a tool to compare the image quality of a new system with the accepted standard. The aim of this study was to obtain a comparable image quality for two systems-storage phosphor plates and a flat-panel system using intravenous urography (IVU) as a clinical model. The image quality figure was calculated using a contrast-detail phantom (CDRAD) for the two evaluated systems. This allowed us to set a dose for the flat-panel system that gave equivalent image quality to the storage phosphor plates. This reduced detector dose was used in an evaluation of clinical images to find out if the dose reduction from the phantom study indeed resulted in images of equal clinical image quality. The image quality was assessed using image criteria of the European guidelines for IVU with visual grading analysis. Equivalent image quality in image pairs was achieved at 30% of the dose. The CDRAD contrast-detail phantom makes it possible to find dose levels that give equal image quality using different imaging systems.

  • 4.
    Johansson, Bengt
    et al.
    Örebro University, School of Health and Medical Sciences.
    Karlsson, Leif
    Örebro University, School of Health and Medical Sciences.
    Hardell, Lennart
    Örebro University, School of Health and Medical Sciences.
    Persliden, Jan
    Örebro University, School of Health and Medical Sciences.
    Pulsed dose rate monobrachytherapy for cancer of the lip: first long time results from a clinical studyManuscript (preprint) (Other academic)
    Abstract [en]

    Background and purpose: To evaluate the long time outcome with regard to local tumour control and side effects of a pulsed dose rate (PDR) monobrachytherapy of primary or recurrent cancr of the lip.

    Patients and methods: Between 1995 and 2007 we treated 43 patients with primary or recurrent T1-T3 lip cancers. The clinical stage was T1N0 for 22 patients (51 %), T2N0 for 16 patients (37 %) and T3N0 for 5 patients (12 %). A median dose of 60 (55-66) Gy was given, depending on the tumour volume. The PDR treatment was given with 0.83 Gy/pulse every second hour for 5.5-6.5 days. The patients were followed for a median of 55 (1-158) months.

    Results: The 2-, 5- and 10-years rates of actuarial local control were 97.6 %, 94.5 % and 94.5 %, overall survival 88.0 %, 58.9 % and 39.1 %, disease free survival 92.7 %, 86.4 % and 86.4 % respectively. The regional control rate was 93 %. One patient (2 %) developed distant metastases. A dosimetrical analysis showed a mean treated volume of 14.9 (3.0-56.2) cm3.  In a review of late complications we found 1 (2 %) soft tissue necrosis and 1 (2 %) osteoradionecrosis. Long-term side effects were very mild and the cosmetic outcome excellent.

    Conclusions: Local outcome is excellent and very similar to other published studies of continuous low dose rate (cLDR) brachytherapy.

  • 5.
    Johansson, Bengt
    et al.
    Örebro University, School of Health and Medical Sciences.
    Karlsson, Leif
    Örebro University, School of Health and Medical Sciences.
    Liljegren, Göran
    Örebro University, School of Health and Medical Sciences.
    Hardell, Lennart
    Persliden, Jan
    Örebro University, School of Health and Medical Sciences.
    Pulsed dose rate brachytherapy as the sole adjuvant radiotherapy after breast-conserving surgery of T1-T2 breast cancer: first long time results from a clinical study2009In: Radiotherapy and Oncology, ISSN 0167-8140, E-ISSN 1879-0887, Vol. 90, no 1, p. 30-35Article in journal (Refereed)
    Abstract [en]

    BACKGROUND AND PURPOSE: To evaluate the long time outcome with regard to local tumour control, cosmetic outcome and side effects of a short (5 days) accelerated interstitial brachytherapy treatment delivered to the surroundings of the operated sector. PATIENTS AND METHODS: Between 1993 and 2003 we treated 50 women with early T1 and T2 breast cancer. Radical sector resection was performed and followed later with an interstitial pulsed dose rate (PDR) brachytherapy of 50Gy in 5 days. The treatment was centred on the tumour with a margin of 30mm. One patient was treated bilaterally. The patients were followed for a median of 86 (32-126) months. RESULTS: Ipsilateral breast cancer recurrence was seen in 3 patients (6%). Two of them occurred outside the treated volume. The 5- and 7-year rates of actuarial local control were 96% and 96%, respectively, overall survival 88% and 85%, disease free survival 88% and 88%, respectively. A dosimetrical analysis showed that the partial breast irradiation covered a median of 31% of the total breast volume. Fat necrosis was seen in 12% and local (moderate-strong) fibrosis in 26% of the patients. Independent cosmetic scoring showed good or excellent result in 56% of the patients. CONCLUSIONS: Local outcome is favourable and very similar to other published studies of accelerated partial breast irradiation. Our long time cosmetic results are lower than other published results.

  • 6.
    Johansson, Bengt
    et al.
    Örebro University, School of Health and Medical Sciences.
    Karlsson, Leif
    Örebro University, School of Health and Medical Sciences.
    Reizenstein, Johan
    Örebro University, School of Health and Medical Sciences.
    von Beckerath, Mathias
    Örebro University, School of Health and Medical Sciences.
    Hardell, Lennart
    Örebro University, School of Health and Medical Sciences.
    Persliden, Jan
    Örebro University, School of Health and Medical Sciences.
    Long term results from a uniform clinical series on pulsed dose rate brachytherapy as the boost to external beam irradiation in base of tongue cancerManuscript (preprint) (Other academic)
    Abstract [en]

    Background and purpose: To evaluate the long time outcome with regard to local tumour control, side effects and quality of life of a combined pulsed dose rate (PDR) boost and hyperfractionated accelerated external beam radiotherapy (EBRT) for primary base of tongue (BOT) cancers.

    Patients and methods: Between 1994 and 2007 we treated 83 patients, median age 60 (38-82) years, with primary T1-T4 BOT cancers. Seven patients (8 %) were T1-2N0 (AJCC stage I-II) and 76 (92 %) patients were T1-2N+ or T3-4N0-3 (AJCC stage III-IV). The mean estimated primary tumour volume was 15 (1-75) cm3.  EBRT was given with 1.7 Gy twice daily to 40,8 Gy to primary tumour and bilateral neck lymph nodes in 2.5 weeks. A PDR boost of 35 Gy and a neck dissection in clinical node positive cases was performed 2-3 weeks later. The patients were followed for a median of 54 (2-168) months.

    Results: The 2-, 5- and 10-years rates of actuarial local control were 91 %, 89 % and 85 %, overall survival 85 %, 65 % and 44 %, disease free survival 86 %, 80 % and 76 % respectively. The regional contral rate was 95 %. Six patients (7 %) developed distant metastases. Analysis of dosimetry showed a mean treated volume of 58 cm3.  In a review of late complications we found 11 (13 %) minor and 4 (5 %) major soft tissue necroses and 6 (7 %) osteoradionecroses. The patients median subjective SOMA/LENT scoring at last follow up was; grade 0 for pain and trismus, grade 1 for dysphagia and taste alteration and grade 2 for xerostomia. Global visual-analog-scale (VAS) scoring of quality of life was 8.

    Conclusions: Local and regional tumour control rate was excellent in this treatment protocol. The data support that PDR boost is at least as effective as published continuous low dose rate (CLDR) results.

  • 7.
    Johansson, Bengt
    et al.
    Örebro University, Department of Clinical Medicine.
    Persson, Essie
    Örebro University, Department of Clinical Medicine.
    Westman, Gunnar
    Örebro University, Department of Clinical Medicine.
    Persliden, Jan
    Örebro University, Department of Clinical Medicine.
    Phantom study of radiation doses outside the target volume brachytherapy versus external radiotherapy of early breast cancer2003In: Radiotherapy and Oncology, ISSN 0167-8140, E-ISSN 1879-0887, Vol. 69, no 1, p. 107-112Article in journal (Refereed)
    Abstract [en]

    BACKGROUND AND PURPOSE: Brachytherapy is sometimes suggested as an adjuvant treatment after surgery of some tumours. When introducing this, it would be useful to have an estimate of the dose distribution to different body sites, both near and distant to target, comparing conventional external irradiation to brachytherapy. The aim of the present study was to determine radiation doses with both methods at different body sites, near and distant to target, in an experimental situation on an operated left sided breast cancer on a female Alderson phantom. METHODS: Five external beam treatments with isocentric tangential fields were given by a linear accelerator. A specified dose of 1.0 Gy was given to the whole left sided breast volume. Five interstitial brachytherapy treatments were given to the upper, lateral quadrant of the left breast by a two plane, 10 needles implant. A dose of 1.0 Gy specified according to the Paris system was administered by a pulsed dose rate afterloading machine. Absorbed dose in different fixed dose points were measured by thermoluminescence dosimeters. RESULTS: Both methods yielded an absorbed dose of the same size to the bone marrow and internal organs distant to target, 1.0-1.4% of the prescribed dose. There was a trend of lower doses to the lower half of the trunk and higher doses to the upper half of the trunk, respectively, by brachytherapy. A 90% reduction of absorbed dose with brachytherapy compared to external irradiation was found in the near-target region within 5 cm from target boundary where parts of the left lung and the heart are situated. If an adjuvant dose of 50 Gy is given with the external radiotherapy and brachytherapy, the absorbed dose in a part of the myocardium could be reduced from 31.8 to 2.1 Gy. CONCLUSIONS: Near target, brachytherapy yielded a considerably lower absorbed dose which is of special importance when considering radiation effects on the myocard and lungs. We could not demonstrate any difference of importance, in absorbed dose to dose points distant to target.

  • 8.
    Karlsson, Leif
    et al.
    Örebro University, School of Health and Medical Sciences, Örebro University, Sweden. Department of Medical Physics, Örebro University Hospital, Örebro, Sweden.
    Thunberg, Per
    Örebro University, School of Health and Medical Sciences, Örebro University, Sweden. Örebro University Hospital. Department of Medical Physics, Örebro University Hospital, Örebro, Sweden.
    Johansson, Bengt
    Örebro University, School of Health and Medical Sciences, Örebro University, Sweden. Örebro University Hospital. Department of Oncology, Örebro University Hospital, Örebro, Sweden.
    Persliden, Jan
    Örebro University, School of Health and Medical Sciences, Örebro University, Sweden. Örebro University Hospital. Department of Medical Physics, Örebro University Hospital, Örebro, Sweden.
    The impact of activating source dwell positions outside the CTV on the dose to treated normal tissue volumes in TRUS guided 3D conformal interstitial HDR brachytherapy of prostate cancer2014In: Journal of Contemporary Brachytherapy, ISSN 1689-832X, E-ISSN 2081-2841, Vol. 6, no 3, p. 282-288Article in journal (Refereed)
    Abstract [en]

    Purpose: Dose coverage is crucial for successful treatment in mono-brachytherapy. Since few and very high dose fractions are used, there is an important balance between dwell positioning outside the clinical target volume (CTV) and possible damage on adjacent normal tissue. The purpose of this study was to evaluate the possibility of having dwell positions close to the CTV surface, while maintaining an acceptable dose distribution, and to investigate the robustness in terms of known geometrical uncertainties of the implant.

    Material and methods: This study included 37 patients who had received brachytherapy for prostate cancer as a monotherapy with the following schedules: 2 x 14 Gy or 3 x 11 Gy, each fraction separated by two weeks. The source dwell positions were activated 5 mm outside CTV. New optimizations were simulated for dwell positions at 3, 2, 1, and 0 mm. Inverse and graphical optimization were applied according to the relative dose constraints: V-100 CTV >= 97%, D-max,D- urethra <= 110%, and D-10 rectal mucosa <= 65%. The V-100 normal tissue outside CTV was used to evaluate dose variations caused by different dwell positions. Prostate geometries and dose distributions for the different dwell positions outside the CTV were used to investigate the impact on the CTV dose distribution due to geometrical uncertainties.

    Results: Both V-100,V- CTV, and V-100,V- normal tissue decreased, 98.6% to 92.2%, and 17 cm(3) to 9.0 cm(3), for dwell activation from 5 rum to 0 mm. The evaluation of both simulated longitudinal geometrical uncertainties and different source dwell activations implied that V-100,V- CTV ranged from 98.6% to 86.3%.

    Conclusions: It is possible to reduce the V-100,V- normal tissue by decreasing the source dwell positions outside the CTV from 5 to 3 mm, while maintaining dose constraints. In combination with the estimated geometrical uncertainties, however, the source dwell positions need to be 5 mm from the surface in order to maintain a robust implant.

  • 9.
    Norrman, Eva
    et al.
    Örebro University, Department of Natural Sciences.
    Geijer, Håkan
    Persliden, Jan
    Örebro University, School of Health and Medical Sciences.
    Optimization of image process parameters through factorial experiments using a flat panel detector2007In: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 52, no 17, p. 5263-5276Article in journal (Refereed)
    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.

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