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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
Stockholm University, Faculty of Science, Medical Radiation Physics (together with KI).
Stockholm University, Faculty of Science, Medical Radiation Physics (together with KI).
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.

Place, publisher, year, edition, pages
2010. Vol. 26, no 1, 6-16 p.
Keyword [en]
Light ion transport, Fluence, Planar fluence, Energy fluence, Mean energy, Absorbed dose
National Category
Physical Sciences
Identifiers
URN: urn:nbn:se:su:diva-25652DOI: 10.1016/j.ejmp.2009.02.003OAI: oai:DiVA.org:su-25652DiVA: diva2:200130
Note
Part of urn:nbn:se:su:diva-8343Available from: 2008-11-24 Created: 2008-11-21 Last updated: 2010-12-17Bibliographically approved
In thesis
1. Development of analytical transport methods for biologically optimized light ion therapy
Open this publication in new window or tab >>Development of analytical transport methods for biologically optimized light ion therapy
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
Radiotherapy, radiation quality, energy-range relations, light ion transport, pencil beam, Monte Carlo
National Category
Physical Sciences
Research subject
Medical Radiation Physics
Identifiers
urn:nbn:se:su:diva-8343 (URN)978-91-7155-783-4 (ISBN)
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

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