Publications by authors named "Karin Petruson"

9 Publications

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Synthetic computed tomography data allows for accurate absorbed dose calculations in a magnetic resonance imaging only workflow for head and neck radiotherapy.

Phys Imaging Radiat Oncol 2021 Jan 11;17:36-42. Epub 2021 Jan 11.

Department of Radiation Physics, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.

Background And Purpose: Few studies on magnetic resonance imaging (MRI) only head and neck radiation treatment planning exist, and none using a generally available software. The aim of this study was to evaluate the accuracy of absorbed dose for head and neck synthetic computed tomography data (sCT) generated by a commercial convolutional neural network-based algorithm.

Materials And Methods: For 44 head and neck cancer patients, sCT were generated and the geometry was validated against computed tomography data (CT). The clinical CT based treatment plan was transferred to the sCT and recalculated without re-optimization, and differences in relative absorbed dose were determined for dose-volume-histogram (DVH) parameters and the 3D volume.

Results: For overall body, the results of the geometric validation were (Mean ± 1sd): Mean error -5 ± 10 HU, mean absolute error 67 ± 14 HU, Dice similarity coefficient 0.98 ± 0.05, and Hausdorff distance difference 4.2 ± 1.7 mm. Water equivalent depth difference for region Th1-C7, mid mandible and mid nose were -0.3 ± 3.4, 1.1 ± 2.0 and 0.7 ± 3.8 mm respectively. The maximum mean deviation in absorbed dose for all DVH parameters was 0.30% (0.12 Gy). The absorbed doses were considered equivalent (p-value < 0.001) and the mean 3D gamma passing rate was 99.4 (range: 95.7-99.9%).

Conclusions: The convolutional neural network-based algorithm generates sCT which allows for accurate absorbed dose calculations for MRI-only head and neck radiation treatment planning. The sCT allows for statistically equivalent absorbed dose calculations compared to CT based radiotherapy.
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http://dx.doi.org/10.1016/j.phro.2020.12.007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8058030PMC
January 2021

Structure delineation in the presence of metal - A comparative phantom study using single and dual-energy computed tomography with and without metal artefact reduction.

Phys Imaging Radiat Oncol 2019 Jan 13;9:43-49. Epub 2019 Feb 13.

Department of Diagnostic Radiation Physics, Medical Physics and Biomedical Engineering, Sahlgrenska University Hospital, SE-41345 Gothenburg, Sweden.

Background And Purpose: Metal artefacts in computed tomography (CT) images impairs structure delineation. These artefacts can potentially be reduced with dual-energy CT (DECT) with or without using metal artefact reduction (MAR). The purpose was to investigate how structure delineation in DECT with or without MAR and single-energy CT (SECT) images were affected by metals.

Materials And Methods: A phantom with known irregular structures was developed. Reference structures were determined from a low-noise scan without metal. Bilateral hip prostheses were simulated with steel or titanium inserts. The phantom was scanned with SECT and fast-kV switching DECT with optional MAR. Four radiation oncologists delineated the structures in two phantom set-ups. Delineated structures were evaluated with Dice similarity coefficient (DSC) and Hausdorff distance relative to the reference structures.

Results: With titanium inserts, more structures were detected for non-MAR DECT compared to SECT while the same or less were detected with steel inserts. MAR improved delineation in DECT images. For steel inserts, three structures in the region of artefacts, were delineated by at least two oncologists with MAR-DECT compared to none with non-MAR DECT or SECT. The highest values of DSC for MAR-DECT were 0.69, 0.81 and 0.77 for those structures.

Conclusions: Delineation was improved with non-MAR DECT compared to SECT, especially for titanium inserts. A larger improvement was seen with the use of MAR for both steel and titanium inserts. The improvement was dependent on the location of the structure relative to the inserts, and the structure contrast relative to the background.
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http://dx.doi.org/10.1016/j.phro.2019.01.001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7807554PMC
January 2019

MR-OPERA: A Multicenter/Multivendor Validation of Magnetic Resonance Imaging-Only Prostate Treatment Planning Using Synthetic Computed Tomography Images.

Int J Radiat Oncol Biol Phys 2017 11 16;99(3):692-700. Epub 2017 Jun 16.

Department of Radiation Sciences, Umeå University, Umeå, Sweden.

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 imaging-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 the MriPlanner 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 imaging-only workflow using MriPlanner is robust for a variety of field strengths, vendors, and treatment techniques.
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http://dx.doi.org/10.1016/j.ijrobp.2017.06.006DOI Listing
November 2017

Results of preoperative chemoradiotherapy for patients with advanced cancer of the nasal cavity and paranasal sinuses.

Acta Otolaryngol 2017 Dec 27;137(12):1292-1300. Epub 2017 Jul 27.

a Department of Oncology, Institute of Clinical Sciences , Sahlgrenska Academy at the University of Gothenburg, Sahlgrenska University Hospital , Gothenburg , Sweden.

Objectives: Curative treatment of nasal cavity and paranasal sinus cancer is challenging due to the proximity to critical anatomical structures. The purpose of this study was to analyze the impact of trimodality therapy with preoperative chemotherapy and reduced-dose radiotherapy followed by organ-preserving surgery for treating patients with nasal cavity and paranasal sinus cancer.

Methods: This retrospective study included all 156 patients diagnosed with sinonasal cancer in western Sweden between 1986 and 2009. We determined the treatment selection pattern and treatment outcomes for 79 patients treated with preoperative chemoradiotherapy.

Results: Squamous cell carcinoma was the most common histology. The five-year overall survival was 54%, and 85% of these patients had T3 or T4 tumors. The five-year cumulative incidence rate of local recurrence was 32%. The five-year overall survival in patients with squamous cell carcinoma and adenocarcinoma was 45% and 76%, respectively. The median preoperative radiation dose was 48 Gy. Orbital exenteration was performed in 7% of patients.

Conclusions: Preoperative chemoradiotherapy may be beneficial for patients with advanced sinonasal cancer when primary radical surgery is challenging. Survival outcomes were comparable to outcomes reported in the literature despite conservative surgery and relatively low radiation doses in patients with locally advanced tumors.
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http://dx.doi.org/10.1080/00016489.2017.1357081DOI Listing
December 2017

Longitudinal evaluation of patients with cancer in the oral tongue, tonsils, or base of tongue--does interstitial radiation dose affect quality of life?

Brachytherapy 2005 ;4(4):271-7

Department of Otorhinolaryngology Head and Neck Surgery, Sahlgrenska University Hospital, Göteborg University, Sweden.

Purpose: To evaluate health-related quality of life (HRQL) in patients with oral tongue, tonsil, or base of tongue cancer in a prospective longitudinal study and explore correlations between HRQL scores and interstitial radiation dose, dose rate, and volume of implant.

Methods And Materials: Ninety patients with oral tongue cancer (n=30) and tonsil or base of tongue cancer (n=60) were assessed with the European Organization of Research and Treatment of Cancer Quality of Life Questionnaire Core-30 and the European Organization of Research and Treatment of Cancer Head and Neck module at diagnosis, and after 3, 12, and 36 months of starting treatment.

Results: The HRQL of all patients decreased during treatment. Most HRQL scores returned to baseline values after 3 years; however, 60% of patients with oral tongue cancer and 80% with tonsil and base of tongue cancer reported problems with dry mouth and half of the patients with tonsil and base of tongue cancer reported problems with swallowing solid food at the 3-year followup. No correlations between brachytherapy quality indices and HRQL scores were found.

Conclusions: Patients with oral tongue, tonsil, or base of tongue cancer reported significant problems with dry mouth and swallowing solid food throughout this 3-year followup study.
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http://dx.doi.org/10.1016/j.brachy.2005.06.001DOI Listing
September 2006

Quality of life as predictor of weight loss in patients with head and neck cancer.

Head Neck 2005 Apr;27(4):302-10

Department of Otorhinolaryngology Head and Neck Surgery, Sahlgrenska University Hospital, S-413 45 Göteborg, Sweden.

Background: The purpose of this prospective study was to evaluate whether a relationship exists between malnutrition (> or =10% weight loss) and health-related quality of life (HRQL) in patients with head and neck cancer and whether weight loss can be predicted with HRQL questionnaires.

Methods: Weight and HRQL were monitored in 49 patients. HRQL was assessed longitudinally, using the European Organization for Research and Treatment of Cancer Quality of Life Core Questionnaire (EORTC QLQ-C30), the EORTC Head and Neck Cancer module (QLQ-H&N35), and the Hospital Anxiety and Depression Scale (HADS).

Results: At diagnosis, those patients who had a weight loss greater than 10% (n = 20) after treatment scored significantly worse on 15 of 28 HRQL variables than did patients who lost less (n = 29). The largest difference (Delta > or =20) was found for role functioning, fatigue, loss of appetite, global quality of life, sticky saliva, and swallowing. Differences in HRQL persisted even after 3 years. The fatigue scale was the only significant predictor of weight loss (p = .005) at diagnosis.

Conclusions: Patients with head and neck cancer who are at risk of severe weight loss developing during treatment may be detected with the aid of HRQL questionnaires at diagnosis.
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http://dx.doi.org/10.1002/hed.20172DOI Listing
April 2005

Effects of psychosocial intervention on quality of life in patients with head and neck cancer.

Head Neck 2003 Jul;25(7):576-84

Department of Otorhinolaryngology Head and Neck Surgery, Sahlgrenska University Hospital, S-413 45 Göteborg, Sweden.

Background: A longitudinal, prospective, case-control study evaluated if a psychosocial support program improved health-related quality of life (HRQL) in head and neck (H&N) cancer patients.

Methods: One hundred forty-four H&N cancer patients were included: 52 study patients and 92 controls. The study group met the support team repeatedly throughout the first year after diagnosis. HRQL was assessed three times during the first year and after 3 years using the EORTC QLQ-C30, EORTC QLQ-H&N35, and HADS.

Results: A few statistically significant differences were found, all favoring the controls. Controls reported better global quality of life after 1 year and felt less ill after 3 years. Depression and treatment-related side effects were prevalent in both groups.

Conclusions: Our psychosocial support program did not improve HRQL in H&N cancer patients. Its effectiveness may be improved by evaluating and actively integrating HRQL assessments during the program, thereby enabling rapid and adequate symptomatic treatment and/or psychologic intervention.
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http://dx.doi.org/10.1002/hed.10243DOI Listing
July 2003

The effect of omalizumab on nasal allergic inflammation.

J Allergy Clin Immunol 2002 Jul;110(1):68-71

Asthma and Allergy Research Group, Department of Respiratory Medicine and Allergology, Sahlgrenska University Hospital, Göteborg, Sweden.

Background: In sensitized patients, coupling between IgE and FcepsilonRI receptors on mast cells leads to release of proinflammatory mediators and a subsequent influx of inflammatory cells to the affected organ. Omalizumab (Xolair; formerly rhuMAb-E25) binds to circulating IgE, thus preventing induction of the allergic process.

Objective: We investigated the effect of treatment with omalizumab on seasonal allergic rhinitis and related changes in inflammatory cell numbers in nasal biopsy specimens.

Methods: Patients were randomized to treatment with omalizumab or placebo before the pollen season; the treatment was started and continued during season. Symptoms and use of medication were recorded, and blood samples and nasal biopsy specimens were obtained before and during season. Immunocytochemistry was performed on biopsy sections through use of the following antibodies: anti-CD4, CD8 (T lymphocytes), EG2, and anti-eosinophil peroxidase (eosinophils), anti-tryptase (mast cells), human neutrophil lipocalin (neutrophils), and antibodies against IgE and FcepsilonRI.

Results: During the season, blood eosinophils increased in placebo-treated patients but not in omalizumab-treated patients (P =.01); the difference between the treatment groups was significant (P =.04). Free IgE in serum decreased significantly (P =.0002) in omalizumab-treated patients but not in placebo-treated patients; the difference between the groups was significant (P =.0001). In nasal biopsy specimens, the number of eosinophil peroxidase-positive staining cells increased in the placebo-treated patients (P =.003) but not in the actively treated patients during the season; the difference between the groups was significant (P =.0001). The number of IgE(+) staining cells decreased significantly in the omalizumab group during the season in comparison with the placebo group (P =.04).

Conclusion: The clinical benefit of treatment with omalizumab is associated with an anti-inflammatory effect on cellular markers in blood and nasal tissue.
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http://dx.doi.org/10.1067/mai.2002.125488DOI Listing
July 2002

Juvenile nasopharyngeal angiofibroma: long-term results in preoperative embolized and non-embolized patients.

Acta Otolaryngol 2002 Jan;122(1):96-100

Department of Otorhinolaryngology, Sahlgrenska University Hospital, Göteborg, Sweden.

A treatment and follow-up study of 32 patients with juvenile nasopharyngeal angiofibroma (JNA) was performed at our clinic between 1974 and 1998. The majority had undergone surgery either via an antral approach or with a lateral rhinotomy. In the 1970s, surgery was combined with ligature of the external carotid artery and, since 1981, it has been combined with preoperative embolization. Two patients received radiotherapy (45 Gy) as primary treatment and the 3 cases of multiple recurrence received radiotherapy (30-45 Gy) as secondary treatment. No recurrence was found in patients treated with radiotherapy. The overall recurrence rate was 25%; the recurrence rate in non-embolized patients was 8% and among embolized patients it was 41%. We found no statistically verified differences in recurrence rate between embolized and non-embolized patients. No statistically significant difference was found in either recurrence or peroperative bleeding when comparing preoperatively embolized patients with non-embolized patients. Regression analyses showed that the only factor affecting recurrence was age, i.e. the younger the patient was at diagnosis the greater the risk of developing recurrence. The development of imaging and embolization techniques will hopefully contribute in the future towards reducing the recurrence rate.
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http://dx.doi.org/10.1080/00016480252775814DOI Listing
January 2002
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