| 1. |
- Costa Ferreira, Brigida, 1972-
(author)
-
Biological optimization of angle of incidence and intensity modulation in breast and cervix cancer radiation therapy
- 2004
-
Doctoral thesis (other academic/artistic)abstract
- Biological treatment optimization aim at improving radiation therapy by accounting for the radiobiological tumour and normal tissues response properties when optimizing the dose delivery. Generally traditional methods, using only dosimetrical measures, disregard the nonlinear radiation response of different tumours and normal tissues. The accumulated knowledge on tissue response to radiation, in the form of more accurate dose response relations, cell survival models and their associated biological parameters, alongside with the tools for biological treatment plan optimization, has allowed the present investigation on the potential merits of biologically based treatment optimization in radiation therapy.With a more widespread implementation of intensity modulated radiation therapy in the clinic, there is an increasing demand for faster and safer treatment delivery techniques. In this thesis biological treatment plan optimization, using the probability to achieve complication free tumour control as the quantifier for treatment outcome, was applied to radiation therapy of early breast cancer and advanced cervix cancer. It is shown that very conformal dose distributions can generally be produced with 3 or 4 optimally orientated coplanar intensity modulated beams, without having clinically significant losses in treatment outcome from the optimal dose distribution.By using exhaustive search methods, the optimal coplanar beam directions for intensity modulated photon beams for early breast cancer and the optimal non-coplanar directions for an advanced cervix cancer were investigated. Although time consuming, exhaustive search methods have the advantage of revealing most features involving interactions between a small number of beams and how this may influence the treatment outcome. Thus phase spaces may serve as a general database for selecting an almost optimal treatment configuration for similar patients. Previous knowledge acquired with physically optimized uniform beam radiation therapy may not apply when intensity modulated biological optimization is used. Thus unconventional treatment directions were sometimes found.
|
|
| 2. |
- Danielsson, Mats, Professor, et al.
(author)
-
Diagnostic and therapeutic detector system for imaging with low and high energy X-ray and electrons
- 2002
-
Patent (pop. science, debate, etc.)abstract
- A detector unit for detecting photons in the energy range 1 keV to 100 MeV, includes at least two converter layers adapted to interact with incident X-ray photons and to cause electrons to be emitted therefrom, at least one amplifier adapted to interact with the electrons emitted from the converters and adapted to produce a multiplicity of secondary electrons and photons representing a signal proportional to the incident fluence of X-ray photons, a connector connecting the detector to an electric field generator providing an electric drift field for secondary electrons in the detector, and a sensor device arranged to receive the signal and provide an input to electronic signal processor.
|
|
| 3. |
- Iacobaeus, Christian, et al.
(author)
-
A novel portal imaging device for advanced radiation therapy
- 2001
-
In: Nuclear Science, IEEE Transactions on. - Nuclear Science, IEEE Transactions on : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9499 .- 1558-1578. ; 48:4, Part 2, s. 1496-1502
-
Journal article (peer-reviewed)
|
|
| 4. |
- Mattsson, Sören, et al.
(author)
-
Swedish Cancer Society radiation therapy research investigation
- 2002
-
In: Acta Oncologica. - 0284-186X .- 1651-226X. ; 41:7-8, s. 596-603
-
Journal article (peer-reviewed)abstract
- In an investigation by the Swedish Cancer Society, the present status, critical issues and future aspects and prospects were described by an expert group for each of nine major areas of radiation research. A summary of the investigation is presented in this report. A more extensive summary (in Swedish) can be found at www.Cancerfonden.se. It is concluded that radiation therapy plays an increasingly important role in curative and palliative tumour treatment and presents a considerable challenge to research. Several suggestions are made that could improve the possibilities for high-quality radiation therapy research in Sweden.
|
|
| 5. |
|
|
| 6. |
- Mavroidis, Panayiotis, et al.
(author)
-
Statistical methods for clinical verification of dose-response parameters related to esophageal stricture and AVM obliteration from radiotherapy
- 2004
-
In: Physics in Medicine and Biology. - : IOP Publishing. - 0031-9155 .- 1361-6560. ; 49:16, s. 3797-3816
-
Journal article (peer-reviewed)abstract
- The purpose of this work is to provide some statistical methods for evaluating the predictive strength of radiobiological models and the validity of dose-response parameters for tumour control and normal tissue complications. This is accomplished by associating the expected complication rates, which are calculated using different models, with the clinical follow-up records. These methods are applied to 77 patients who received radiation treatment for head and neck cancer and 85 patients who were treated for arteriovenous malformation (AVM). The three-dimensional dose distribution delivered to esophagus and AVM nidus and the clinical follow-up results were available for each patient. Dose-response parameters derived by a maximum likelihood fitting were used as a reference to evaluate their compatibility with the examined treatment methodologies. The impact of the parameter uncertainties on the dose-response curves is demonstrated. The clinical utilization of the radiobiological parameters is illustrated. The radiobiological models (relative seriality and linear Poisson) and the reference parameters are validated to prove their suitability in reproducing the treatment outcome pattern of the patient material studied (through the probability of finding a worse fit, area under the ROC curve and chi2 test). The analysis was carried out for the upper 5 cm of the esophagus (proximal esophagus) where all the strictures are formed, and the total volume of AVM. The estimated confidence intervals of the dose-response curves appear to have a significant supporting role on their clinical implementation and use.
|
|
| 7. |
- Nilsson, Johan, 1971-
(author)
-
Accurate description of heterogeneous tumors for biologically optimized radiation therapy
- 2004
-
Doctoral thesis (other academic/artistic)abstract
- In this thesis, a model of tissue oxygenation is presented, that takes into account the heterogeneous nature of tumor vasculature. Even though the model is rather simple, the resulting oxygen distributions agree very well with clinically observed oxygen distributions for most tumors and healthy normal tissues. The model shows that the vascular density may not describe the oxygenation of a tissue sufficiently well, unless the heterogeneity of the vascular system is taken into account. Based on the oxygen distributions from the tissue model, the associated radiation response at low and high doses can be determined. The radiation response of heterogeneous tumors should preferably be described by two clonogen compartments, one resistant and one sensitive, dominating the response at high and low radiation doses, respectively. Furthermore, each compartment should be characterized by the effective radiation resistance and the effective clonogen number. The resistant-sensitive model of radiation response has been analyzed in great detail. It accurately describes the response of severely heterogeneous tumors, both at low and high doses and LET values. The effective response parameters are given as integrals, averaged over the whole spectrum of radiation resistance. The parameters can also be determined from clinically established dose-response relations. The main properties of the dose-response relation for a generally heterogeneous tumor is described in some detail. The normalized dose-response gradient has been generalized to take heterogeneities in both dose delivery and radiation response into account. This quantity is important for accurate treatment plan optimization using intensity modulated radiation therapy for individual patients.
|
|
| 8. |
|
|
| 9. |
|
|
| 10. |
- Qatarneh, Sharif M., et al.
(author)
-
A whole body atlas for segmentation and delineation of organs for radiation therapy planning
- 2001
-
In: Nuclear Instruments and Methods in Physics Research Section A. - Berlin, Heidelberg : Springer. - 0168-9002 .- 1872-9576. ; 471, s. 160-164, s. 1168-1169
-
Journal article (peer-reviewed)abstract
- A semi-automatic procedure for delineation of organs, to be used as the basis of a whole body atlas database for radiation therapy planning was developed. The Visible Human Male Computed Tomography (CT)-data set was used as a standard man reference. The organ of interest was outlined manually and then transformed by a polynomial warping algorithm onto a clinical patient CT. This provided an initial contour, which was then adjusted and refined by the semi-automatic active contour model to find the final organ outline. The liver was used as a test organ for evaluating the performance of the procedure. Liver outlines obtained by the segmentation algorithm on six patients were compared to those manually drawn by, a radiologist. The combination of warping and semi-automatic active contour model generally provided satisfactory segmentation results, but the procedure has to be extended to three dimensions.
|
|
