| 1. |
- Adjeiwaah, Mary, 1980-, et al.
(författare)
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Dosimetric Impact of MRI Distortions : A Study on Head and Neck Cancers
- 2019
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Ingår i: International Journal of Radiation Oncology, Biology, Physics. - : Elsevier. - 0360-3016 .- 1879-355X. ; 103:4, s. 994-1003
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To evaluate the effect of magnetic resonance (MR) imaging (MRI) geometric distortions on head and neck radiation therapy treatment planning (RTP) for an MRI-only RTP. We also assessed the potential benefits of patient-specific shimming to reduce the magnitude of MR distortions for a 3-T scanner.Methods and Materials: Using an in-house Matlab algorithm, shimming within entire imaging volumes and user-defined regions of interest were simulated. We deformed 21 patient computed tomography (CT) images with MR distortion fields (gradient nonlinearity and patient-induced susceptibility effects) to create distorted CT (dCT) images using bandwidths of 122 and 488 Hz/mm at 3 T. Field parameters from volumetric modulated arc therapy plans initially optimized on dCT data sets were transferred to CT data to compute a new plan. Both plans were compared to determine the impact of distortions on dose distributions.Results: Shimming across entire patient volumes decreased the percentage of voxels with distortions of more than 2 mm from 15.4% to 2.0%. Using the user-defined region of interest (ROI) shimming strategy, (here the Planning target volume (PTV) was the chosen ROI volume) led to increased geometric for volumes outside the PTV, as such voxels within the spinal cord with geometric shifts above 2 mm increased from 11.5% to 32.3%. The worst phantom-measured residual system distortions after 3-dimensional gradient nonlinearity correction within a radial distance of 200 mm from the isocenter was 2.17 mm. For all patients, voxels with distortion shifts of more than 2 mm resulting from patient-induced susceptibility effects were 15.4% and 0.0% using bandwidths of 122 Hz/mm and 488 Hz/mm at 3 T. Dose differences between dCT and CT treatment plans in D-50 at the planning target volume were 0.4% +/- 0.6% and 0.3% +/- 0.5% at 122 and 488 Hz/mm, respectively.Conclusions: The overall effect of MRI geometric distortions on data used for RTP was minimal. Shimming over entire imaging volumes decreased distortions, but user-defined subvolume shimming introduced significant errors in nearby organs and should probably be avoided.
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| 2. |
- Adjeiwaah, Mary, et al.
(författare)
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Quantifying the Effect of 3T Magnetic Resonance Imaging Residual System Distortions and Patient-Induced Susceptibility Distortions on Radiation Therapy Treatment Planning for Prostate Cancer
- 2018
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Ingår i: International Journal of Radiation Oncology, Biology, Physics. - : Elsevier. - 0360-3016 .- 1879-355X. ; 100:2, s. 317-324
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Tidskriftsartikel (refereegranskat)abstract
- 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%.
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| 3. |
- Adra, Jamila, et al.
(författare)
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Distribution of locoregional breast cancer recurrence in relation to postoperative radiation fields and biological subtypes.
- 2019
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Ingår i: International journal of radiation oncology, biology, physics. - : Elsevier BV. - 1879-355X .- 0360-3016. ; 105:2, s. 285-295
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Tidskriftsartikel (refereegranskat)abstract
- and purpose: To investigate incidence and location of locoregional recurrence (LRR) in patients who have received postoperative locoregional radiotherapy (LRRT) for primary breast cancer. LRR-position in relation to applied radiotherapy and the primary tumours biological subtype were analysed with the aim to evaluate current target guidelines and RT techniques in relation to tumour biology.Medical records were reviewed for all patients who received postoperative LRRT for primary BC in southwestern Sweden from 2004-2008 (N=923). Patients with LRR as a first event were identified (N=57, distant failure and death were considered competing risks). CT images identifying LRR were used to compare LRR locations to postoperative LRRT fields. LRR risk and distribution were then related to the primary BC biological subtype and to current target guidelines.Cumulative LRR incidence after 10 years was 7.1% (95%CI 5.5-9.1). Fifty-seven of the 923 patients in the cohort developed LRR (30 local recurrences (LR), 30 regional recurrences (RR), of which 3 cases of simultaneous LR/RR). Most cases of LRR developed fully (56%) or partially (26%) within postoperatively irradiated areas. The most common location for out-of-field RR was cranial to RT fields in the supraclavicular fossa. Patients with an ER- (HR 4.6, p<0.001, 95%CI 2.5-8.4) or HER2+ (HR 2.4, p=0.007, 95%CI 1.3-4.7) primary BC presented higher risks of LRR compared to those with ER+ tumours. ER-/HER2+ tumours more frequently recurred in-field (68%) rather than marginal/out-of-field (32%). In addition, 75% of in-field recurrences derived from an ER-/HER+ tumour, compared to 45% of marginal/out-of-field recurrences. A complete pathological response in the axilla after neoadjuvant treatment was associated with a lower degree of LRR risk (p=0.022).Incidence and locations of LRR seems to be related to the primary BC biological subtype. Individualized LRRT according to tumour biology may be applied to improve outcomes.
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| 4. |
- Beasley, W., et al.
(författare)
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Image-based Data Mining to Probe Dosimetric Correlates of Radiation-induced Trismus
- 2018
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Ingår i: International Journal of Radiation Oncology Biology Physics. - : Elsevier BV. - 0360-3016. ; 102:4, s. 1330-1338
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To identify imaged regions in which dose is associated with radiation-induced trismus after head and neck cancer radiation therapy (HNRT) using a novel image-based data mining (IBDM) framework. Methods and Materials: A cohort of 86 HNRT patients were analyzed for region identification. Trismus was characterized as a continuous variable by the maximum incisor-to-incisor opening distance (MID) at 6 months after radiation therapy. Patient anatomies and dose distributions were spatially normalized to a common frame of reference using deformable image registration. IBDM was used to identify clusters of voxels associated with MID (P <= .05 based on permutation testing). The result was externally tested on a cohort of 35 patients with head and neck cancer. Internally, we also performed a dose-volume histogram-based analysis by comparing the magnitude of the correlation between MID and the mean dose for the IBDM-identified cluster in comparison with 5 delineated masticatory structures. Results: A single cluster was identified with the IBDM approach (P < .01), partially overlapping with the ipsilateral masseter. The dose-volume histogram-based analysis confirmed that the IBDM cluster had the strongest association with MID, followed by the ipsilateral masseter and the ipsilateral medial pterygoid (Spearman's rank correlation coefficients: R-s = -0.36, -0.35, -0.32; P = .001, .001, .002, respectively). External validation confirmed an association between mean dose to the IBDM cluster and MID (R-s = -0.45; P = .007). Conclusions: IBDM bypasses the common assumption that dose patterns within structures are unimportant. Our novel IBDM approach for continuous outcome variables successfully identified a cluster of voxels that are highly associated with trismus, overlapping partially with the ipsilateral masseter. Tests on an external validation cohort showed an even stronger correlation with trismus. These results support use of the region in HNRT treatment planning to potentially reduce trismus. (C) 2018 Elsevier Inc. All rights reserved.
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| 5. |
- Bosco, Cecilia, et al.
(författare)
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Prostate Cancer Radiation Therapy and Risk of Thromboembolic Events
- 2017
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Ingår i: International Journal of Radiation Oncology, Biology, Physics. - : ELSEVIER SCIENCE INC. - 0360-3016 .- 1879-355X. ; 97:5, s. 1026-1031
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To investigate the risk of thromboembolic disease (TED) after radiation therapy (RT) with curative intent for prostate cancer (PCa).Patients and Methods: We identified all men who received RT as curative treatment (n=9410) and grouped according to external beam RT (EBRT) or brachytherapy (BT). By comparing with an age-and county-matched comparison cohort of PCa-free men (n = 46,826), we investigated risk of TED after RT using Cox proportional hazard regression models. The model was adjusted for tumor characteristics, demographics, comorbidities, PCa treatments, and known risk factors of TED, such as recent surgery and disease progression.Results: Between 2006 and 2013, 6232 men with PCa received EBRT, and 3178 underwent BT. A statistically significant association was found between EBRT and BT and risk of pulmonary embolism in the crude analysis. However, upon adjusting for known TED risk factors these associations disappeared. No significant associations were found between BT or EBRT and deep venous thrombosis.Conclusion: Curative RT for prostate cancer using contemporary methodologies was not associated with an increased risk of TED.
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| 6. |
- Câmara-Costa, Hugo, et al.
(författare)
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Neuropsychological Outcome of Children Treated for Standard Risk Medulloblastoma in the PNET4 European Randomized Controlled Trial of Hyperfractionated Versus Standard Radiation Therapy and Maintenance Chemotherapy.
- 2015
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Ingår i: International journal of radiation oncology, biology, physics. - : Elsevier BV. - 1879-355X .- 0360-3016. ; 92:5, s. 978-85
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Tidskriftsartikel (refereegranskat)abstract
- In the European HIT-SIOP PNET4 randomized controlled trial, children with standard risk medulloblastoma were allocated to hyperfractionated radiation therapy (HFRT arm, including a partially focused boost) or standard radiation therapy (STRT arm), followed, in both arms, by maintenance chemotherapy. Event-free survival was similar in both arms. Previous work showed that the HFRT arm was associated with worse growth and better questionnaire-based executive function, especially in children <8 years of age at diagnosis. Therefore, the aim of this study was to compare performance-based cognitive outcomes between treatment arms.
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| 7. |
- Cederkrantz, Elin, et al.
(författare)
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Absorbed Doses and Risk Estimates of (211)At-MX35 F(ab')2 in Intraperitoneal Therapy of Ovarian Cancer Patients.
- 2015
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Ingår i: International journal of radiation oncology, biology, physics. - : Elsevier BV. - 1879-355X .- 0360-3016. ; 93:3, s. 569-76
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Tidskriftsartikel (refereegranskat)abstract
- Ovarian cancer is often diagnosed at an advanced stage with dissemination in the peritoneal cavity. Most patients achieve clinical remission after surgery and chemotherapy, but approximately 70% eventually experience recurrence, usually in the peritoneal cavity. To prevent recurrence, intraperitoneal (i.p.) targeted α therapy has been proposed as an adjuvant treatment for minimal residual disease after successful primary treatment. In the present study, we calculated absorbed and relative biological effect (RBE)-weighted (equivalent) doses in relevant normal tissues and estimated the effective dose associated with i.p. administration of (211)At-MX35 F(ab')2.
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| 8. |
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| 9. |
- Egevad, L, et al.
(författare)
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In Regard to Zietman et al
- 2016
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Ingår i: International journal of radiation oncology, biology, physics. - : Elsevier BV. - 1879-355X .- 0360-3016. ; 96:5, s. 1126-
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 10. |
- Eriksson, Mina, et al.
(författare)
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Analysis of Chromatin Opening in Heterochromatic Non-Small Cell Lung Cancer Tumor-Initiating Cells in Relation to DNA-Damaging Antitumor Treatment
- 2018
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Ingår i: International Journal of Radiation Oncology, Biology, Physics. - : Elsevier BV. - 0360-3016 .- 1879-355X. ; 100:1, s. 174-187
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: We previously reported that sphere-forming non-small cell lung cancer (NSCLC) tumor-initiating cells (TICs) have an altered activation of DNA damage response-and repair proteins and are refractory to DNA-damaging treatments. We analyzed whether chromatin organization plays a role in the observed refractoriness.Methods and Materials: Bulk cells and TICs from the NSCLC H23 and H1299 cell lines were examined using cell viability, clonogenic survival, Western blot, short interfering RNA analysis, and micronucleus assay.Results: NSCLC TICs displayed elevated heterochromatin markers trimethylated lysine 9 of histone H3 and heterochromatin protein 1 gamma relative to bulk cells and reduced cell viability upon histone deacetylase inhibition (HDACi). Vorinostat and trichostatin A increased the euchromatin markers acetylated lysine 9/14 of histone H3 and lysine 8 of histone H4, and HDACi pretreatment increased the phosphorylation of the DNA damage response proteins ataxia telangiectasia mutated and DNA-dependent protein kinase, catalytic subunit, upon irradiation in TICs. HDACi sensitized TICs to cisplatin and to some extent to ionizing irradiation. The protectiveness of a dense chromatin structure was indicated by an enhanced frequency of micronuclei in TICs following irradiation, after knockdown of heterochromatin protein 1 gamma.Conclusions: Although confirmatory studies in additional NSCLC model systems and with respect to analyses of other DNA damage response proteins are needed, our data point toward a heterochromatic structure of NSCLC TICs, such that HDACi can sensitize TICs to DNA damage.
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