| 1. |
- Johansson, Bengt, 1958-, et al.
(författare)
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Phantom study of radiation doses outside the target volume brachytherapy versus external radiotherapy of early breast cancer
- 2003
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Ingår i: Radiotherapy and Oncology. - Amsterdam : Elsevier. - 1879-0887 .- 0167-8140. ; 69:1, s. 107-112
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Tidskriftsartikel (refereegranskat)abstract
- 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. (C) 2003 Elsevier Ireland Ltd. All rights reserved.
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| 2. |
- Mu, Xiangkui, et al.
(författare)
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The effect of fraction time in intensity modulated radiotherapy : theoretical and experimental evaluation of an optimisation problem.
- 2003
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Ingår i: Radiotherapy and Oncology. - 0167-8140 .- 1879-0887. ; 68:2, s. 181-187
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND AND PURPOSE: In intensity modulated radiotherapy (IMRT), the complexity and the number of treatment fields have expanded. This may imply that the delivery time for each fraction becomes prolonged. In a number of IMRT techniques used in the clinic, the delivery time per fraction is usually 10-15 min, sometimes more than 15 min. In studies on human skin, prolonged delivery time is shown to cause significant reduction of radiation effects compared with acute irradiation. In this paper the effect of changes in fraction delivery time was studied by in vitro irradiation of mammalian cells. MATERIAL AND METHODS: Chinese hamster fibroblasts (V79-379-A) were used for simulating clinical situations. Most experiments were performed with 2Gy/fraction with 4-h intervals in 40-60 replicates. Each fraction was divided into different subfractions, simulating the delivery of a complicated treatment. The effect of changing the delivery time for each fraction was studied. Parameters for the cell survival curve and repair kinetics were determined experimentally. The same methods were also used for large fraction sizes (8Gy). The validity of the most widely used models in the literature, all derived from linear-quadratic formalism, were tested against the experimental results. RESULTS: The effect of prolonging the fraction time for 2-Gy fractions was underestimated by the biological models. The experiments showed that 10-min prolonged delivery time gave a ratio between surviving fractions at 2Gy (S-ratio) of 1.054 with a 95% confidence interval (CI) 1.030-1.080, while the models predicted 1.007 and 1.009. Extending the fraction time to 20 min gave an S-ratio of 1.063 with CI of 1.045-1.080, while the models predicted 1.012 and 1.014. For 8-Gy fractions, there was a good agreement between predications and experimental results. The ratio between surviving fractions at 8Gy is 1.370 with CI of 1.300-1.440, while the models predicated 1.37 and 1.35. CONCLUSIONS: The effect of prolonging fraction time at conventional dose/fraction is underestimated by biological models. Prolonging the fraction time will spare tissues with a fast DNA repair. There is a risk for sparing tumours. This should be considered when IMRT technique is implemented in the clinic.
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| 3. |
- Olofsson, Jörgen, et al.
(författare)
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A widely tested model for head scatter influence on photon beam output
- 2003
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Ingår i: Radiotherapy and Oncology. - 0167-8140 .- 1879-0887. ; 67:2, s. 225-238
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To construct and test a semi-analytical model describing the effects on Monitor Unit (MU) verification caused by scattering in the treatment head. The implementation of the model should be accomplished using a small set of experimental data. Furthermore, the model should include a geometry dependent estimation of the resulting uncertainty. Material and methods: The input required by the created model consists of basic treatment head geometry and 10 measured output factors in air (OFair) for square fields. It considers primary energy fluence, scattered radiation from an extra-focal source and from secondary collimators, as well as backscatter to the monitor chamber. Measurements and calculations were performed in open symmetric and asymmetric fields at points located both on and off the collimator axis, as well as at arbitrary treatment distances. The model has been verified for 19 photon beams in the range from 4 up to 50 MV, provided by nine different treatment units from six manufacturers. Results: The presented model provided results with errors smaller than 1% (2 S.D.) in typical clinical situations for all beams tested. In more exceptional situations, i.e. combinations of unconventional treatment head designs, very elongated fields, and dosimetry points far away from the isocenter, the total uncertainty increased to approximately 2%. The spread in the results was further analysed in order to create a method for predicting the uncertainties under different treatment conditions. Conclusions: A general head scatter model that is easy to implement has been developed and can be used as the basis for computerised MU verification. The model handles all commercially available treatment units adequately and also includes an estimation of the resulting uncertainty.
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| 4. |
- Toma-Dasu, Iuliana, et al.
(författare)
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Theoretical simulation of oxygen tension measurement in the tissue using a microelectrode: II. Simulated measurements in tissues
- 2002
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Ingår i: Radiotherapy and Oncology. - 0167-8140 .- 1879-0887. ; 64:1, s. 109-118
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND AND PURPOSE: The objectives of this study were to make a computer simulation of tissues with different vascular structures and to simulate measurements of oxygen tension using an Eppendorf-like electrode in these tissues and to compare the response to radiation of the tissues with the real oxygen distributions (called input distribution) with the response to radiation of the tissues in which the oxygen distribution is given by the results of the simulated measurements (called output distribution).MATERIALS AND METHODS: The structure of various tissues and the measurements of oxygen tension using a microelectrode were simulated using a computer program. The mathematical model used combines the description of a gradient of tissue oxygenation and the electrode absorption process.RESULTS: We have compared the oxygen distributions resulting from diffusion (input) with those obtained from a simulation of measurements (output) for various tissues in the same points. Because the electrode measurement is an averaging process, the calculated oxygen distributions are different from the expected ones and the extreme high and low values are not detected. We have then calculated the survival curves describing the response to radiation if there is a small fraction of truly hypoxic cells (expected values) or a large fraction of cells at intermediate values (observed results) in order to determine the differences between them.CONCLUSIONS: The results of our study show that oxygen electrode measurements do not give the true distribution of pO(2) values in the tissue. However, our results do not contradict the numerous empirical correlations between the Eppendorf measurements of tumour oxygenation and the outcome of treatments. Measurement results will be misleading for modelling purposes since they do not reflect the actual distributions of oxygen tensions in the measured tissue. Decisions based on such modelling could be very dangerous, especially with respect to the clinical response of tumours to new treatments.
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| 5. |
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| 6. |
- Waligórski, Michael P R, et al.
(författare)
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Cellular parameters and RBE-LET dependences for modelling heavy-ion radiotherapy.
- 2004
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Ingår i: Radiother Oncol. - : Elsevier BV. - 0167-8140 .- 1879-0887. ; 73:Supplement 2, s. S173-175
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Tidskriftsartikel (refereegranskat)abstract
- Sets of four parameters (m, Eo, ~o and •) of the cellular track structure model of Katz have been fitted to recently published dataconcerning human melanoma (AA) and mammalian (V79) cells exposed to a variety of lighter ions and to mixed ion-Co60 and ionionirradiation. We discuss the predictive capability of this model and propose standards in reporting cellular radiobiology data forapplication in modelling heavy ion beam radiotherapy.
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| 7. |
- Wengström, Yvonne, 1959-, et al.
(författare)
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Quantitative assessment of skin erythema following breast cancer RT
- 2003
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Ingår i: Radiotherapy and Oncology. - 0167-8140 .- 1879-0887. ; 68, s. S20-S20
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Tidskriftsartikel (refereegranskat)abstract
- Visual assessment is the most common clinical investigation of skin reactions in radiotherapy. Due to the unquantitative and subjective nature of this method additional non-invasive methods are needed for more accurate evaluation of the visible acute adverse skin reactions due to radiotherapy• The purpose of this study was to evaluate a new objective measure with regard to reliability and validity and compare it with an established objective measure and a visual assessment.Material and Methods: A sample of fifty-three consecutive patients commencing curative tangential radiation therapy to the breast parenchyma was included in the study• The skin area of the treated breast was divided into five sections and assessed individually at 0 Gy, 24 Gy and 50 Gy. The RTOG scoring system was used for the visual assessment of the skin reactions. The first objective measure included reflectance spectrometry (DermaSpectrometer) measures at fixed points within the treatment area. For the second objective measure digital images were taken with a system using a digital camera and software. The images were analyzed using the Adobe Photoshop 5•0 software program•Results: The results provided significant evidence of the test-retest reliability of the camera• The correlation between the objective measures proved to be significant as the treatment progressed• The results suggest that the Camera may be used in a reliable and valid way to measure skin erythema due to radiotherapy•
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| 8. |
- Coffey, M, et al.
(författare)
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Revised European core curriculum for RTs
- 2004
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Ingår i: Radiotherapy and Oncology. - : Elsevier BV. - 1879-0887 .- 0167-8140. ; 70:2, s. 137-158
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Forskningsöversikt (refereegranskat)abstract
- Aim: To update the first version of the European core curriculum to reflect many developments in radiotherapy and educational philosophy that have taken place in the interim period. Materials and methods: The first version of the European core curriculum was reviewed by the Steering Group together with current education programmes from the various member states and taking into account the developments and changes that have taken place in radiotherapy. From these initial meetings, a working document and provisional timetable were prepared, Given the diversity of the existing programmes, the language difficulties and lack of national curricula it was agreed that a representative from both the clinical and academic areas endorsed by their national professional body would be identified for each country. These participants were then invited to participate in two workshops and the working document and timetable were circulated. Two workshops were held and a final draft document was circulated to the professional bodies and other interested groups. Results: The revised European Core Curriculum for RTTs was endorsed by the participants of the workshops representing academic and clinical areas of all the member states and was welcomed by the wider circulation. Compared to the first version the revised curriculum describes the background underpinning the practice of radiation therapy and the variation across the member states, issues of staffing, educational philosophy, certification level, legislation governing recognition of qualifications and a core syllabus. Conclusion: The revised core curriculum is an important step in the progress of professional recognition for RTTs, towards harmonisation of education programmes in Europe and meeting the aim of best practice and equality of care for all patients receiving radiotherapy. Responsibility for developing education programmes from the curriculum will rest with the local and/or national education bodies and authorities. (C) 2003 Elsevier Ireland Ltd. All rights reserved.
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| 9. |
- Eudaldo, T, et al.
(författare)
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Guidelines for education and training of medical physicists in radiotherapy - Recommendations from an ESTRO/EFOMP working group
- 2004
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Ingår i: Radiotherapy and Oncology. - : Elsevier BV. - 1879-0887 .- 0167-8140. ; 70:2, s. 125-135
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To provide a guideline curriculum covering theoretical and practical aspects of education and training for medical physicists in radiotherapy within Europe. Material and methods: Guidelines have been developed for the specialist theoretical knowledge and practical experience required to practice as a medical physicist in radiotherapy. It is assumed that the typical entrant into training will have a good initial degree in the physical sciences, therefore these guidelines also require that and are additional to it. National training programmes of medical physics, radiation physics and radiotherapy physics from a range of European countries and from North America were reviewed by an expert panel set up by the European Society of Therapeutic Radiology and Oncology (ESTRO) and the European Federation of Organisations for Medical Physics (EFOMP). A draft document prepared by this group was circulated, via the EFOMP infrastructure, among national professional medical physics societies in Europe for review and comment and was also discussed in an education session in the May 2003 EFOMP scientific meeting in Eindhoven. Results: The resulting guideline curriculum for education and training of medical physicists in radiotherapy within Europe discusses the EFOMP terms, qualified medical physicist (QMP) and specialist medical physicist (SMP), and the group's view of the links to the EU (Directive 97/43) term, medical physics expert (MPE). The minimum level expected in each topic in the theoretical knowledge and practical experience sections is intended to bring trainees up to the requirements of a QMP. The responses from the circulation of the document to national societies and its discussion were either to agree its content, with no changes required, or to suggest changes, which were taken into account after consideration by the expert group. Following this the guidelines have been endorsed by the parent organisations. Conclusions: This new joint ESTRO/EFOMP European guideline curriculum is a first step to harmonise specialist training of medical physicists in radiotherapy within Europe. It provides a common framework for national medical physics societies to develop or benchmark their own curricula, but is also flexible enough to suit different situations of initial physics qualifications, medical physics training programmes, accreditation structures, etc. The responsibility for the implementation of these standards and guidelines will lie with the national training bodies and authorities.
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| 10. |
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