TU Darmstadt / ULB / TUprints

Comprehensive comparison of local effect model IV predictions with the particle irradiation data ensemble

Pfuhl, Tabea ; Friedrich, Thomas ; Scholz, Michael (2022)
Comprehensive comparison of local effect model IV predictions with the particle irradiation data ensemble.
In: Medical Physics, 2022, 49 (1)
doi: 10.26083/tuprints-00020984
Article, Secondary publication, Publisher's Version

[img] Text
Copyright Information: CC BY 4.0 International - Creative Commons, Attribution.

Download (903kB)
Item Type: Article
Type of entry: Secondary publication
Title: Comprehensive comparison of local effect model IV predictions with the particle irradiation data ensemble
Language: English
Date: 11 July 2022
Place of Publication: Darmstadt
Year of primary publication: 2022
Publisher: Wiley
Journal or Publication Title: Medical Physics
Volume of the journal: 49
Issue Number: 1
DOI: 10.26083/tuprints-00020984
Corresponding Links:
Origin: Secondary publication DeepGreen

Purpose: The increased relative biological effectiveness (RBE) of ions is one of the key benefits of ion radiotherapy compared to conventional radiotherapy with photons. To account for the increased RBE of ions during the process of ion radiotherapy treatment planning, a robust model for RBE predictions is indispensable. Currently, at several ion therapy centers the local effect model I (LEM I) is applied to predict the RBE, which varies with biological and physical impacting factors. After the introduction of LEM I, several model improvements were implemented, leading to the current version, LEM IV, which is systematically tested in this study.

Methods: As a comprehensive RBE model should give consistent results for a large variety of ion species and energies, the particle irradiation data ensemble (PIDE) is used to systematically validate the LEM IV. The database covers over 1100 photon and ion survival experiments in form of their linear‐quadratic parameters for a wide range of ion types and energies. This makes the database an optimal tool to challenge the systematic dependencies of the RBE model. After appropriate filtering of the database, 571 experiments were identified and used as test data.

Results: The study confirms that the LEM IV reflects the RBE systematics observed in measurements well. It is able to reproduce the dependence of RBE on the linear energy transfer (LET) as well as on the αγ/βγ ratio for several ion species in a wide energy range. Additionally, the systematic quantitative analysis revealed precision capabilities and limits of the model. At lower LET values, the LEM IV tends to underestimate the RBE with an increasing underestimation with increasing atomic number of the ion. At higher LET values, the LEM IV overestimates the RBE for protons or helium ions, whereas the predictions for heavier ions match experimental data well.

Conclusions: The LEM IV is able to predict general RBE characteristics for several ion species in a broad energy range. The accuracy of the predictions is reasonable considering the small number of input parameters needed by the model. The detailed quantification of possible systematic deviations, however, enables to identify not only strengths but also limitations of the model. The gained knowledge can be used to develop model adjustments to further improve the model accuracy, which is on the way.

Uncontrolled Keywords: local effect model, model validation, PIDE, RBE
Status: Publisher's Version
URN: urn:nbn:de:tuda-tuprints-209849
Classification DDC: 500 Science and mathematics > 530 Physics
Divisions: 05 Department of Physics > Institute for Condensed Matter Physics
Date Deposited: 11 Jul 2022 13:39
Last Modified: 14 Nov 2023 19:04
SWORD Depositor: Deep Green
URI: https://tuprints.ulb.tu-darmstadt.de/id/eprint/20984
PPN: 498915689
Actions (login required)
View Item View Item