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Optimizing normal tissue sparing in ion therapy using calculated isoeffective dose for ion selection.
- Source :
-
International journal of radiation oncology, biology, physics [Int J Radiat Oncol Biol Phys] 2012 Jun 01; Vol. 83 (2), pp. 756-62. Date of Electronic Publication: 2012 Mar 19. - Publication Year :
- 2012
-
Abstract
- Purpose: To investigate how the selection of ion type affects the calculated isoeffective dose to the surrounding normal tissue as a function of both normal tissue and target tissue α/β ratios.<br />Methods and Materials: A microdosimetric biologic dose model was incorporated into a Geant4 simulation of parallel opposed beams of protons, helium, lithium, beryllium, carbon, and neon ions. The beams were constructed to give a homogeneous isoeffective dose to a volume in the center of a water phantom for target tissues covering a range of cobalt equivalent α/β ratios of 1-20 Gy. Concomitant normal tissue isoeffective doses in the plateau of the ion beam were then compared for different ions across the range of normal tissue and target tissue radiosensitivities for a fixed isoeffective dose to the target tissue.<br />Results: The ion type yielding the optimal normal tissue sparing was highly dependent on the α/β ratio of both the normal and the target tissue. For carbon ions, the calculated isoeffective dose to normal tissue at a 5-cm depth varied by almost a factor of 5, depending on the α/β ratios of the normal and target tissue. This ranges from a factor of 2 less than the isoeffective dose of a similar proton treatment to a factor of 2 greater.<br />Conclusions: No single ion is optimal for all treatment scenarios. The heavier ions are superior in cases in which the α/β ratio of the target tissue is low and the α/β ratio of normal tissue is high, and protons are superior in the opposite circumstances. Lithium and beryllium appear to offer dose advantages similar to carbon, with a considerably lower normal tissue dose when the α/β ratio in the target tissue is high and the α/β ratio in the normal tissue is low.<br /> (Copyright © 2012 Elsevier Inc. All rights reserved.)
- Subjects :
- Beryllium therapeutic use
Carbon therapeutic use
Heavy Ion Radiotherapy
Helium therapeutic use
Lithium therapeutic use
Monte Carlo Method
Neon therapeutic use
Organ Sparing Treatments methods
Phantoms, Imaging
Proton Therapy
Radiation Tolerance
Radiotherapy Dosage
Relative Biological Effectiveness
Ions therapeutic use
Models, Biological
Organ Sparing Treatments standards
Organs at Risk radiation effects
Subjects
Details
- Language :
- English
- ISSN :
- 1879-355X
- Volume :
- 83
- Issue :
- 2
- Database :
- MEDLINE
- Journal :
- International journal of radiation oncology, biology, physics
- Publication Type :
- Academic Journal
- Accession number :
- 22436796
- Full Text :
- https://doi.org/10.1016/j.ijrobp.2011.08.006