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Development of analytical transport methods for biologically optimized light ion therapy
Stockholm University, Faculty of Science, Medical Radiation Physics (together with KI).
2008 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

A general objective in the treatment of cancer is to eradicate the tumour cells without inducing severe complications in healthy normal tissue. The use of light ions for radiation therapy increases the possibility to deliver tumour suicidal doses with very low probability of normal tissue injury, not least in cases where the target is unresectable, radioresistant and located to near organs at risk. The success in the application of such beams in radiation therapy is largely determined by a thorough understanding of particle transport, biological dose response relations and their accurate integration in the treatment planning system. The focus has therefore been on the radiation quality of the light ions, their transport and to develop analytical tools and theories for their application in biologicallly optimized radiation treatment planning. New radiation quality results has been presented, new analytical approaches for the light ion transport in matter have been developed and new range concepts have been defined. A refined version of the Monte Code SHIELD-HIT was developed and used for calculating fundamental physical transport quantities that could be directly compared with the analytical theories and methods as well as with experimental data. The present results could be useful for biological optimized treatment planning, biologically optimized dose delivery techniques, dosimetry and for in vivo dose delivery verification.

Place, publisher, year, edition, pages
Stockholm: Medicinsk strålningsfysik (tills m KI) , 2008. , 44 p.
Keyword [en]
Radiotherapy, radiation quality, energy-range relations, light ion transport, pencil beam, Monte Carlo
National Category
Physical Sciences
Research subject
Medical Radiation Physics
Identifiers
URN: urn:nbn:se:su:diva-8343ISBN: 978-91-7155-783-4 (print)OAI: oai:DiVA.org:su-8343DiVA: diva2:200132
Public defence
2008-12-16, föreläsningssalen, Cancer Centrum Karolinska, R8:00, Karolinska universitetssjukhuset, Solna, 09:15
Opponent
Supervisors
Available from: 2008-11-24 Created: 2008-11-21 Last updated: 2013-01-17Bibliographically approved
List of papers
1. Depth dose and LET distributions of 1H,4He, 7Li and 12C ions in therapeutic light ion beams
Open this publication in new window or tab >>Depth dose and LET distributions of 1H,4He, 7Li and 12C ions in therapeutic light ion beams
2007 In: Medical Physics, ISSN 0094-2405, Vol. 34, no 1, 183-192 p.Article in journal (Refereed) Published
Identifiers
urn:nbn:se:su:diva-25650 (URN)000243574500020 ()
Note
Part of urn:nbn:se:su:diva-8343Available from: 2008-11-24 Created: 2008-11-21Bibliographically approved
2. Energy-range relation and mean energy variation in therapeutic particle beams
Open this publication in new window or tab >>Energy-range relation and mean energy variation in therapeutic particle beams
2008 (English)In: Medical physics (Lancaster), ISSN 0094-2405, Vol. 35, no 1, 159-170 p.Article in journal (Refereed) Published
Abstract [en]

Analytical expressions for the mean energy and range of therapeutic light ion beams and low- and high-energy electrons have been derived, based on the energy dependence of their respective stopping powers. The new mean energy and range relations are power-law expressions relevant for light ion radiation therapy, and are based on measured practical ranges or known tabulated stopping powers and ranges for the relevant incident particle energies. A practical extrapolated range, Rp, for light ions was defined, similar to that of electrons, which is very closely related to the extrapolated range of the primary ions. A universal energy-range relation for light ions and electrons that is valid for all material mixtures and compounds has been developed. The new relation can be expressed in terms of the range for protons and alpha particles, and is found to agree closely with experimental data in low atomic number media and when the difference in the mean ionization energy is low. The variation of the mean energy with depth and the new energy-range relation are useful for accurate stopping power and mass scattering power calculations, as well as for general particle transport and dosimetry applications.

Keyword
biological techniques, dosimetry, particle beams, radiation therapy, energy-range relations, mean energy variations, universal energy-range relation, ion practical range
National Category
Physical Sciences
Identifiers
urn:nbn:se:su:diva-25651 (URN)10.1118/1.2815935 (DOI)000251910300019 ()
Available from: 2008-11-24 Created: 2008-11-21 Last updated: 2012-03-08Bibliographically approved
3. Analytical theory for the fluence, planar fluence, energy fluence, planar energy fluence and absorbed dose of primary particles and their fragments in broad therapeutic light ion beams
Open this publication in new window or tab >>Analytical theory for the fluence, planar fluence, energy fluence, planar energy fluence and absorbed dose of primary particles and their fragments in broad therapeutic light ion beams
2010 (English)In: Physica medica (Testo stampato), ISSN 1120-1797, E-ISSN 1724-191X, Vol. 26, no 1, 6-16 p.Article in journal (Refereed) Published
Abstract [en]

The purpose of the present work is to develop analytical expressions for the depth variation of the fluence, planar fluence, the energy fluence, planar energy fluence, the mean energy and absorbed dose of primary ions and their associated fragments in tissue-like media with ranges of clinical interest. The analytical expressions of the primary ions and associated fragments take into account nuclear interactions, energy losses, range straggling and multiple scattering. The analytical models of the radiation field quantities were compared with the results of the modified Monte Carlo (MC) code SHIELD-HIT+. The results show that the shape of the depth absorbed dose distribution of the primary particles is characterized by an increasingly steep exponential fluence decrease with depth as the charge and atomic weight increase. This is accompanied by a compensating increased energy loss towards the Bragg peak as the charge of the ion increases. These largely compensating mechanisms are the main reason that the depth absorbed dose curve of all light ions is surprisingly similar. In addition, a rather uniform dose in the plateau region is obtained since the increasing fragment production almost precisely compensates the loss of primaries. The dominating light fragments such as protons and alpha particles are characterized by longer ranges than the primaries and their depth dose curves to some extent coincide well with the depth fluence curves due to a rather slow variation of mean stopping powers. In contrast, the heavier fragments are characterized by the build up of a slowing down spectrum similar to that of the primaries but with initially slightly shorter or longer ranges depending on their mass to atomic number ratio. The presented analytical theory for the light ion penetration in matter agree quite well with the MC and experimental data and may be very useful for fast analytical calculations of quantities like mean energy, fluence, energy fluence, absorbed dose, and LET.

Keyword
Light ion transport, Fluence, Planar fluence, Energy fluence, Mean energy, Absorbed dose
National Category
Physical Sciences
Identifiers
urn:nbn:se:su:diva-25652 (URN)10.1016/j.ejmp.2009.02.003 (DOI)
Note
Part of urn:nbn:se:su:diva-8343Available from: 2008-11-24 Created: 2008-11-21 Last updated: 2010-12-17Bibliographically approved
4. Solution of the Boltzmann equation for primary light ions and the transport of their fragments
Open this publication in new window or tab >>Solution of the Boltzmann equation for primary light ions and the transport of their fragments
In: Physical Review C, ISSN 0556-2813Article in journal (Refereed) Submitted
Identifiers
urn:nbn:se:su:diva-25653 (URN)
Note
Part of urn:nbn:se:su:diva-8343Available from: 2008-11-24 Created: 2008-11-21Bibliographically approved

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