| 1. |
- Lindholm, C E, et al.
(författare)
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Arterial rupture after microwave-induced hyperthermia and radiotherapy. With reference to two patients treated for recurrence in previously operated and irradiated areas
- 1990
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Ingår i: International Journal of Hyperthermia. - : Informa UK Limited. - 0265-6736 .- 1464-5157. ; 6:3, s. 499-509
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Tidskriftsartikel (refereegranskat)abstract
- Two patients who developed frank arterial bleeding after combined microwave-induced hyperthermia and radiotherapy are described. One patient received re-irradiation and hyperthermia for recurrent metastatic neck nodes of a mesopharyngeal carcinoma. Full course radiotherapy had been given 6 years previously and a right-sided radical neck node dissection had been performed 4 months earlier because of recurrent neck node metastases. Six weeks after the combined therapy for a second recurrence, which achieved complete remission, a fatal rupture of the carotid artery occurred. The other patient received re-irradiation and hyperthermia for a chest wall recurrence of a breast carcinoma, treated 5.5 years previously by sector resection and tangential beam radiotherapy, and treated again 2 years earlier with extensive surgery for a local recurrence. A frank arterial bleeding from the treated region was seen after 7 months, but could be arrested with surgery. This important complication in combined hyperthermia and radiotherapy does not seem to have been recognized before. Different explanations are discussed, such as the previous local treatment as well as high temperature and atherosclerosis per se.
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| 2. |
- Kristensen, Ingrid, et al.
(författare)
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A dose based approach for evaluation of inter-observer variations in target delineation
- 2017
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Ingår i: Technical Innovations and Patient Support in Radiation Oncology. - : Elsevier. - 2405-6324. ; 3-4, s. 41-47
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Tidskriftsartikel (refereegranskat)abstract
- Background and purpose: Substantial inter-observer variations in target delineation have been presented previously. Target delineation for paediatric cases is difficult due to the small number of children, the variation in paediatric targets, the number of study protocols, and the individual patient's specific needs and demands. Uncertainties in target delineation might lead to under-dosage or over-dosage. The aim of this work is to apply the concept of a consensus volume and good quality treatment plans to visualise and quantify inter-observer target delineation variations in dosimetric terms in addition to conventional geometrically based volume concordance indices.Material and methods: Two paediatric cases were used to demonstrate the potential of adding dose metrics when evaluating target delineation diversity; Hodgkin's disease (case 1) and rhabdomyosarcoma of the parotid gland (case 2). The variability in target delineation (PTV delineations) between six centres was quantified using the generalised conformity index, CIgen, generated for volume overlap. The STAPLE algorithm, as implemented in CERR, was used for both cases to derive a consensus volumes. STAPLE is a probabilistic estimate of the true volume generated from all observers. Dose distributions created by each centre for the original target volumes were then applied to this consensus volume.Results: A considerable variation in target segmentation was seen in both cases. For case 1 the variation was 374-960 cm3 (average 669 cm3) and for case 2; 65-126 cm3 (average 109 cm3). CIgen were 0.53 and 0.70, respectively. The DVHs in absolute volume displayed for the delineated target volume as well as for the consensus volume adds information on both ''compliant" target volumes as well as outliers which are hidden with just the use of concordance indices.Conclusions: The DVHs in absolute volume add valuable and easily understood information to various indices for evaluating uniformity in target delineation.
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| 3. |
- Kjellén, Elisabeth, et al.
(författare)
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A Phase I/II Evaluation of Metoclopramide as a Radiosensitiser in Patients with Inoperable Squamous Cell Carcinoma of the Lung
- 1995
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Ingår i: European Journal of Cancer. - : Elsevier BV. - 1879-0852 .- 0959-8049. ; 31:13-14, s. 2196-2202
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Tidskriftsartikel (refereegranskat)abstract
- The feasibility of administering metoclopramide (MCA) as a radiosensitizer has been evaluated in 23 patients with a pathological or cytological diagnosis of a squamous cell carcinoma of the lung, clinically evaluated as inoperable. All patients received 40-60 Gy radiotherapy fractionated into 1.8 Gy fractions 5 times per week (Monday-Friday). Two MCA treatment regimens were used: (i) MCA at 2 mg/kg administered by intravenous infusion 1-2 h prior to radiotherapy 3 times per week (Monday, Wednesday, Friday); and (ii) MCA at 1 mg/kg administered by intravenous infusion 1-2 h prior to radiotherapy 5 times per week (Monday-Friday). 11 of the 23 patients treated with radiotherapy and MCA had none to mild pneumonitis or fibrosis and another 8 of the 23 had moderate levels. No patient had their therapy interrupted due to radiation-related side-effects. The MCA-related side-effects were as expected, i.e. 78% of the patients experienced sedation/tiredness and 48% expressed restlessness/anxiety symptoms. Both the total dose and serum levels of MCA were significantly associated to the MCA side-effect profile. Tumour response, duration of tumour response and survival were significantly positively correlated to the total and weekly doses of MCA administered to the patients during their radiotherapy treatment. These favourable phase II data have justified the initiation of a phase II/III randomised multicentred trial being carried out in Europe to evaluate MCA as a radiosensitiser.
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| 4. |
- Lempart, Michael, et al.
(författare)
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Modifying a clinical linear accelerator for delivery of ultra-high dose rate irradiation
- 2019
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Ingår i: Radiotherapy and Oncology. - : Elsevier BV. - 0167-8140. ; 139, s. 40-45
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: The purpose of this study was to modify a clinical linear accelerator, making it capable of electron beam ultra-high dose rate (FLASH) irradiation. Modifications had to be quick, reversible, and without interfering with clinical treatments. Methods: Performed modifications: (1) reduced distance with three setup positions, (2) adjusted/optimized gun current, modulator charge rate and beam steering values for a high dose rate, (3) delivery was controlled with a microcontroller on an electron pulse level, and (4) moving the primary and/or secondary scattering foils from the beam path. Results: The variation in dose for a five-pulse delivery was measured to be 1% (using a diode, 4% using film) during 10 minutes after a warm-up procedure, later increasing to 7% (11% using film). A FLASH irradiation dose rate was reached at the cross-hair foil, MLC, and wedge position, with ≥30, ≥80, and ≥300 Gy/s, respectively. Moving the scattering foils resulted in an increased output of ≥120, ≥250, and ≥1000 Gy/s, at the three positions. The beam flatness was 5% at the cross-hair position for a 20 × 20 and a 10 × 10 cm2 area, with and without both scattering foils in the beam. The beam flatness was 10% at the wedge position for a 6 and 2.5 cm diametric area, with and without the scattering foils in the beam path. Conclusions: A clinical accelerator was modified to produce ultra-high dose rates, high enough for FLASH irradiation. Future work aims to fine-tune the dose delivery, using the on-board transmission chamber signal and adjusting the dose-per-pulse.
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| 5. |
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| 6. |
- Aarup, Lasse Rye, et al.
(författare)
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The effect of different lung densities on the accuracy of various radiotherapy dose calculation methods: Implications for tumour coverage
- 2009
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Ingår i: Radiotherapy and Oncology. - : Elsevier BV. - 1879-0887 .- 0167-8140. ; 91:3, s. 405-414
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To evaluate against Monte-Carlo the performance of various dose calculations algorithms regarding lung turnout coverage in stereotactic body radiotherapy (SBRT) conditions. Materials and methods: Dose distributions in virtual lung phantoms have been calculated using four commercial Treatment Planning System (TPS) algorithms and one Monte Carlo (MC) system (EGSnrc). We compared the performance of the algorithms in calculating the target dose for different degrees of lung inflation. The phantoms had a cubic 'body' and 'lung' and a central 2-cm diameter spherical 'tumour' (the body and turnout have unit density). The lung tissue was assigned five densities (rho(lung)): 0.01, 0.1, 0.2, 0.4 and 1 g/cm(3). Four-field treatment plans were calculated with 6- and 18 MV narrow beams for each value of rho(lung). We considered the Pencil Beam Convolution (PBCEl) and the Analytical Anisotropic Algorithm (AAA(ECl)) from Varian Eclipse and the Pencil Beam Convolution (PBCOMP) and the Collapsed Cone Convolution (CCCOMP) algorithms from Oncentra MasterPlan. Results: When changing rho(lung) from 0.4 to 0.1 g/cm(3), the MC median target dose decreased from 89.2% to 74.9% for 6 MV and from 83.3% to 61.6% for 18 MV (of dose maximum in the homogenous case at both energies), while for both PB algorithms the median target dose was virtually independent of lung density. Conclusions: Both PB algorithms overestimated the target dose, the overestimation increasing as rho(lung) decreased. Concerning target dose, the AAA(ECl) and CCCOMP algorithms appear to be adequate alternatives to MC. (C) 2009 Elsevier Ireland Ltd. All rights reserved. Radiotherapy and oncology 91 (2009) 405-414
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| 7. |
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| 8. |
- Björk, Peter, et al.
(författare)
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Design and dosimetry characteristics of a soft-docking system for intraoperative radiation therapy
- 2000
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Ingår i: International Journal of Radiation Oncology, Biology, Physics. - 0360-3016. ; 47:2, s. 527-533
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: The design concept and the dosimetric characteristics of an applicator system for intraoperative radiation therapy (IORT) with special emphasis on alignment methods, the effect of a plastic scatterer in the beam, radiation leakage, and misalignment dosimetry, are presented in this paper. MATERIALS AND METHODS: A soft-docking system for a linear accelerator, which enables collimation of electron beams (4-22 MeV) for IORT has been developed. The system includes twenty-one circular polymethylmethacrylate (PMMA) treatment cones of different lengths, diameters and end angles. All in-water measurements are made using p-type silicon diode detectors. RESULTS: The effect of introducing a PMMA scatterer in the therapeutic beam includes increased surface dose values (above 83% for all nominal electron energies and for all cones) and improved dose homogeneity within the therapeutic range. Electrons scattered from the inside wall of the cone result in dose profile horns at depth of dose maximum always lower than 109%. The radiation leakage outside the cone is less than 13%. Large changes in the dose profiles occur if the intraoperative cone is misaligned more than 0.5. CONCLUSION: The alignment procedure of the soft-docking system is easy to handle and the applicator design provides adequate collimation of electron beams for IORT.
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| 9. |
- Björk, Peter, et al.
(författare)
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Dosimetry characteristics of degraded electron beams investigated by Monte Carlo calculations in a setup for intraoperative radiation therapy.
- 2002
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Ingår i: Physics in Medicine and Biology. - : IOP Publishing. - 1361-6560 .- 0031-9155. ; 47:2, s. 239-256
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Tidskriftsartikel (refereegranskat)abstract
- Degraded electron beams, as used for intraoperative radiation therapy (IORT) or similar complicated dosimetric situations, have different characteristics compared to conventional electron therapy beams. If international dosimetry protocols are applied in a direct manner to such degraded beams, uncertainties will be introduced in the absorbed dose determination. The Monte Carlo method has been used to verify experimentally determined relative absorbed dose distributions and output factors in an IORT geometry. Monte Carlo generated dose distributions are mostly within +/-2% or +/-2 mm of measured data. The simulated output variation between the IORT cones (relative output factors) are mostly within 2% of measured values. By comparing IORT and conventional electron beam characteristics (e.g. energy spectra, angular distributions and the contributions of different system components to these quantities) limitations and uncertainties of commonly used dosimetric techniques in IORT electron fields are quantified. The intraoperative treatment field contains a larger amount of scattered electrons, which leads to a broader energy spectrum as well as a wider angular distribution of electrons at the phantom surface. The dose from the scattered electrons can contribute up to 40% of the total dose at a depth of dose maximum, compared to approximately 10% for standard beams. A study of the energy spectra at the reference depth reveals that an uncertainty of the order of 1% can be introduced if ionization chamber based dosimetry is used to determine output factors for the investigated IORT system. We recommend that relative absorbed dose distributions and output factors in IORT electron beams and for similar complicated dosimetric situations should be determined with detectors having a small energy and angular dependence (e.g. diamond detectors or p-Si diodes).
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| 10. |
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