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Vascular structure and binomial statistics for response modeling in radiosurgery of cerebral arteriovenous malformations
Stockholm University, Faculty of Science, Medical Radiation Physics (together with KI). (Medical Radiation Physics)
University of Tehran. (Neurosurgery)
Stockholm University, Faculty of Science, Medical Radiation Physics (together with KI).
Stockholm University, Faculty of Science, Medical Radiation Physics (together with KI).
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2010 (English)In: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 55, no 7, 2057-2067 p.Article in journal (Refereed) Published
Abstract [en]

Radiation treatment of arteriovenous malformations (AVMs) has a slow and progressive vaso-occlusive effect. Some studies suggested the possible role of vascular structure in this process. A detailed biomathematical model has been used, where the morphological, biophysical and hemodynamic characteristics of intracranial AVM vessels are faithfully reproduced. The effect of radiation on plexiform and fistulous AVM nidus vessels was simulated using this theoretical model. The similarities between vascular and electrical networks were used to construct this biomathematical AVM model and provide an accurate rendering of transnidal and intranidal hemodynamics. The response of different vessels to radiation and their obliteration probability as a function of different angiostructures were simulated and total obliteration was defined as the probability of obliteration of all possible vascular pathways. The dose response of the whole AVM is observed to depend on the vascular structure of the intra-nidus AVM. Furthermore, a plexiform AVM appears to be more prone to obliteration compared with an AVM of the same size but having more arteriovenous fistulas. Finally, a binomial model was introduced, which considers the number of crucial vessels and is able to predict the dose response behavior of AVMs with a complex vascular structure.

Place, publisher, year, edition, pages
2010. Vol. 55, no 7, 2057-2067 p.
National Category
Other Medical Sciences not elsewhere specified
URN: urn:nbn:se:su:diva-74962DOI: 10.1088/0031-9155/55/7/017ISI: 000275756200017OAI: diva2:513261
Available from: 2012-04-01 Created: 2012-04-01 Last updated: 2012-10-09Bibliographically approved
In thesis
1. Improving the therapeutic ratio of stereotactic radiosurgery and radiotherapy
Open this publication in new window or tab >>Improving the therapeutic ratio of stereotactic radiosurgery and radiotherapy
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

New methods of high dose delivery, such as intensity modulated radiation therapy (IMRT), stereotactic radiation therapy (SRT) or stereotactic radiosurgery (SRS), hadron therapy, tomotherapy, etc., all make use of a few large fractions. To improve these treatments, there are three main directions: (i) improving physical dose distribution, (ii) optimizing radiosurgery dose-time scheme and (iii) modifying dose response of tumors or normal tissues.

Different radiation modalities and systems have been developed to deliver the best possible physical dose to the target while keeping radiation to normal tissue minimum. Although applications of radiobiological findings to clinical practice are still at an early stage, many studies have shown that   sublethal radiation damage repair kinetics plays an important role in tissue response to radiation.

The purpose of the present thesis is to show how the above-mentioned directions could be used to improve treatment outcomes with special interest in radiation modalities and dose-time scheme, as well as radiobiological modeling. Also for arteriovenous malformations (AVM), the possible impact of AVM network angiostructure in radiation response was studied.

Abstract [sv]

Nya och förbättrade metoder för precisionsbestrålning, såsom intensitetsmodulerad strålbehandling (IMRT), stereotaktisk strålbehandling (SRT), stereotaktisk strålkirurgi (SRS) eller hadronterapi etc., gör det möjligt att leverera behandlingen i ett fåtal fraktioner med höga doser. Dessa behandlingmetoder kan ytterligare förbättras genom att (i) förbättra den fysikaliska dosfördelningen, (ii) optimera dosrater och fraktioneringsscheman eller (iii) modifiera dosresponsen hos tumörer eller normalvävnad.

Olika strålmodaliteter och behandlingssystem har tagits fram för att kunna leverera bästa möjliga fysikaliska dosfördelning till targetvolymen samtidigt som dosen till frisk vävnad hålls så låg som möjligt. Även om användandet av radiobiologisk kunskap och modeller i klinisk rutin ännu är i sin linda så visar många studier att kinetiken för subletal reparation av strålskador har stor betydelse för strålresponsen.

Syftet med denna avhandling är att visa hur dessa olika utvecklingsvägar kan användas för att förbättra behandlingsresultatet speciellt genom att studera vald strålmodalitet, dosrat och fraktioneringsschema samt radiobiologisk modellering. För arteriovenösa missbildningar (AVM) har även  studerats hur strukturen hos angionätverket påverkar strålresponsen.

Place, publisher, year, edition, pages
Stockholm: Department of Physics, Stockholm Univeristy, 2012. 60 p.
optimization, stereotactic radiosurgery, stereotactic radiotherapy, radiobiology, modeling
National Category
Other Physics Topics
Research subject
Medical Radiation Physics
urn:nbn:se:su:diva-81079 (URN)978-91-7447-581-4 (ISBN)
Public defence
2012-11-16, föreläsningssalen, Radiumhemmet, Karolinska universitetssjukhuset, Solna, 10:00 (English)

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.

Available from: 2012-10-25 Created: 2012-10-08 Last updated: 2012-10-31Bibliographically approved

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Andisheh, BahramMavroidis, Panayiotis
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