DOI: 10.4103/jmp.jmp_140_26 ISSN: 0971-6203
FLUKA Monte Carlo-based Evaluation of Linear Energy Transfer Distributions for Monoenergetic Therapeutic Carbon-ion Beams in Water
Arghya Chattaraj, T. Palani Selvam, Vandana Shrivastava Abstract
Background:
This study aims to calculate the distribution of linear energy transfer (
LET
) and its moments such as fluence-averaged
LET
(
LET
f
) and dose-averaged
LET
(
LET
d
) as a function of on-axis depth in water for monoenergetic carbon-ion beams with energies ranging from 80 to 480 MeV/u.
Materials and Methods:
Depth-dose profiles,
LET
distributions,
LET
f
, and
LET
d
are calculated as a function of on-axis depth in a 40 cm × 40 cm × 40 cm unit-density liquid water phantom using the FLUKA Monte Carlo code, fully incorporating the contributions of primary ions and all secondary charged fragments.
Results:
Results show that both
LET
f
and
LET
d
increase with depth and reach a maximum near the Bragg peak region, followed by a rapid fall-off in the distal region as the fluence of heavy ion fragments decreases. Higher beam energies result in deeper
LET
peaks and more pronounced fragmentation tails in the depth-dose profiles. In the Bragg peak region, depending on beam energy, the
LET
f
and
LET
d
values are in the range of 11.7–106.4 keV/mm and 210.7–384.6 keV/mm, respectively.
Conclusion:
Overall, the results provide a comprehensive characterization of physical and radiobiological parameters for monoenergetic carbon-ion beams in the therapeutic energy range, essential for benchmarking
LET
-based RBE models, improving treatment plan robustness, and optimizing biological dose delivery in carbon-ion radiotherapy.