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Development and application of composite energy deposition kernels for photon therapy planning
Stockholm University.
1999 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In recent years, the use of optimization algorithms in radiation therapy planning has increased dramatically. All optimization algorithms as well as most modern implementations of conventional therapy planning, use energy deposition kernels as a fundamental part of the calculations. This work presents the development of a library of elementary and composite energy deposition kernels for photon beam therapy planning. The energy deposition kernels have been calculated for pencil beams, incident on various 2D and 3D geometries as well as for isotropically emitting point sources in the energy range from 0.5 to 50 MeV. Kernels for both monoenergetic photons and calculated and clinical photon spectra have been developed. A volume overlap algorithm has been developed to calculate composite energy deposition kernels for coplanar multiple fields and arc therapy from photon pencil beam kernels. The algorithm has been extended to 3D to enable calculation of energy deposition kernels for arbitrary irradiation geometries as well as isotropic irradiation and point sources. The kernels have then been used to calculate optimal dose distributions for external beam radiation therapy. It has been demonstrated that for simple parallel opposed beam configurations low photon energies are advantageous for small tumors due to their narrow penumbra, whereas larger tumors are best treated with high photon energies in order to save normal tissues along the beam path. For more complex targets and beam directions, especially when using intensity modulated dose delivery, the photon energy is of minor importance.

Place, publisher, year, edition, pages
Stockholm: Stockholm University , 1999. , 33 p.
Keyword [en]
Energy deposition kernels, volume overlap algorithm, radiotherapy planning, photon pencil beams, treatment optimization, biological treatment objectives
National Category
Medical and Health Sciences
Research subject
Medical Radiation Physics
URN: urn:nbn:se:su:diva-64520ISBN: 91-7153-996-4OAI: diva2:458022
Public defence
1999-10-29, 09:15
Härtill 5 uppsatserAvailable from: 2011-11-21 Created: 2011-11-21 Last updated: 2011-11-21Bibliographically approved

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