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Secondary doses in anthropomorphic phantoms irradiated with light ion beams
Stockholm University, Faculty of Science, Department of Physics. (Medicinsk strålningsfysik)
Stockholm University, Faculty of Science, Department of Physics. (Medicinsk strålningsfysik)
2009 (English)In: Nuclear Technology, ISSN 0029-5450, E-ISSN 1943-7471, Vol. 168, no 1, 123-127 p.Article in journal (Refereed) Published
Abstract [en]

The mathematical anthropomorphic phantoms EVA-HIT and ADAM-HIT have been used in the Monte Carlo code SHIELD-HIT07 for simulations of lung tumor and prostate irradiation with light ions. Calculations were performed for 1H, 7Li, and 12C beams of energies in the range of 80 to 330 MeV/u. The secondary doses to organs, due to scattered primary ions and secondary particles produced in the phantoms, were studied taking into account the contribution from secondary neutrons, secondary protons, pions, and heavier fragments from helium to calcium. The doses to organs per dose to target (tumor) are of the order of 10-6 to 10-1 mGy Gy-1 and decrease with increasing distance from the target. In general the organ dose per target dose increases with increasing Z of the primary particle; however, for lighter primary ions (Z 3) and for organs close to the target, scattered primary particles show a nonnegligible dose contribution.

Place, publisher, year, edition, pages
2009. Vol. 168, no 1, 123-127 p.
National Category
Other Physics Topics
Research subject
Medical Radiation Physics
Identifiers
URN: urn:nbn:se:su:diva-64291OAI: oai:DiVA.org:su-64291DiVA: diva2:456781
Available from: 2011-11-15 Created: 2011-11-15 Last updated: 2017-12-08Bibliographically approved
In thesis
1. Secondary absorbed dose distributions and radiation quality in light ion therapy
Open this publication in new window or tab >>Secondary absorbed dose distributions and radiation quality in light ion therapy
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Radiotherapy with light ions offers the possibility of achieving a dose distribution which is highly conformed to the target volume while sparing normal tissues. For ions heavier than protons, an additional advantage is the increased Relative Biological Effectiveness (RBE) as compared to conventional photon and electron beams. During light ion therapy, nuclear fragments are produced in nuclear inelastic collisions of the projectile and the atomic nuclei in the material. In a cascade of events, the nuclear fragments in turn produce secondaries during their transport. The organs of the patient are thus exposed to a complex secondary radiation field and secondary doses can be delivered to normal tissues both close to and relatively far from the treated volume. In this thesis, secondary doses were evaluated in anthropomorphic phantoms which were developed for simulations with the Monte Carlo code SHIELD-HIT. Simulations of lung tumor, prostate and brain tumor irradiation with 1H, 4He, 7Li, 12C and 16O ion beams in the energy range 80-400 MeV/u were performed with SHIELD-HIT. The simulated organ absorbed doses were in the range 10-6-10-1 mGy per treatment Gy. In general, the organ absorbed doses decreased with increasing distance from the target volume and increased with increasing atomic number of the primary ions.

The produced nuclear fragments also influences the radiation quality in the target volume and thus the biological effectiveness of the beam. The dose-mean lineal energy, <yD>, was studied in a 290 MeV/u 12C beam by simulating the energy distributions of both primary and secondary ions and weighting their relative dose fractions with the corresponding energy-dependent <yD> which were obtained by ion-track simulations with PITS99 coupled with the electron transport code KURBUC. <yD> were evaluated in the target volume for object diameters 10-100 nm and were used in estimations of clinically useful weighting factors.

Place, publisher, year, edition, pages
Stockholm: Department of Physics, Stockholm University, 2011. 54 p.
Keyword
secondary doses, light ion therapy, radiation quality, Monte Carlo simulation
National Category
Physical Sciences
Research subject
Medical Radiation Physics
Identifiers
urn:nbn:se:su:diva-64302 (URN)978-91-7447-412-1 (ISBN)
Public defence
2011-12-20, Föreläsningssalen, Cancercentrum Karolinska, R8:00, Karolinska universitetssjukhuset, Solna, 13:00 (English)
Opponent
Supervisors
Note

At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 4: Submitted.

Available from: 2011-11-28 Created: 2011-11-16 Last updated: 2016-01-18Bibliographically approved

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