Dataset Information

Balancing benefits and limitations of linear energy transfer optimization in carbon ion radiotherapy for large sacral chordomas.

ABSTRACT:

Background and purpose

A low linear energy transfer (LET) in the target can reduce the effectiveness of carbon ion radiotherapy (CIRT). This study aimed at exploring benefits and limitations of LET optimization for large sacral chordomas (SC) undergoing CIRT.

Materials and methods

Seventeen cases were used to tune LET-based optimization, and seven to independently test interfraction plan robustness. For each patient, a reference plan was optimized on biologically-weighted dose cost functions. For the first group, 7 LET-optimized plans were obtained by increasing the gross tumor volume (GTV) minimum LET_d (minLET_d) in the range 37-55 keV/μm, in steps of 3 keV/μm. The optimal LET-optimized plan (LET_OPT) was the one maximizing LET_d, while adhering to clinical acceptability criteria. Reference and LET_OPT plans were compared through dose and LETd metrics (D _x , L _x to x% volume) for the GTV, clinical target volume (CTV), and organs at risk (OARs). The 7 held-out cases were optimized setting minLET_d to the average GTV L_98% of the investigation cohort. Both reference and LET_OPT plans were recalculated on re-evaluation CTs and compared.

Results

GTV L_98% increased from (31.8 ± 2.5)keV/μm to (47.6 ± 3.1)keV/μm on the LET_OPT plans, while the fraction of GTV receiving over 50 keV/μm increased on average by 36% (p < 0.001), without affecting target coverage goals, or impacting LET_d and dose to OARs. The interfraction analysis showed no significant worsening with minLET_d set to 48 keV/μm.

Conclusion

LET_d optimization for large SC could boost the LET_d in the GTV without significantly compromising plan quality, potentially improving the therapeutic effects of CIRT for large radioresistant tumors.

SUBMITTER: Parrella G

PROVIDER: S-EPMC11357807 | biostudies-literature | 2024 Jul

REPOSITORIES: biostudies-literature

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Publications

Balancing benefits and limitations of linear energy transfer optimization in carbon ion radiotherapy for large sacral chordomas.

Parrella Giovanni G Magro Giuseppe G Chalaszczyk Agnieszka A Rotondi Marco M Ciocca Mario M Glimelius Lars L Fiore Maria R MR Paganelli Chiara C Orlandi Ester E Molinelli Silvia S Baroni Guido G

Physics and imaging in radiation oncology 20240701

<h4>Background and purpose</h4>A low linear energy transfer (LET) in the target can reduce the effectiveness of carbon ion radiotherapy (CIRT). This study aimed at exploring benefits and limitations of LET optimization for large sacral chordomas (SC) undergoing CIRT.<h4>Materials and methods</h4>Seventeen cases were used to tune LET-based optimization, and seven to independently test interfraction plan robustness. For each patient, a reference plan was optimized on biologically-weighted dose cos ...[more]

PMID: 39206357

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Project description:The purpose of this study was to investigate the feasibility of incorporating linear energy transfer (LET) into the optimization of intensity modulated proton therapy (IMPT) plans. Because increased LET correlates with increased biological effectiveness of protons, high LETs in target volumes and low LETs in critical structures and normal tissues are preferred in an IMPT plan. However, if not explicitly incorporated into the optimization criteria, different IMPT plans may yield similar physical dose distributions but greatly different LET, specifically dose-averaged LET, distributions. Conventionally, the IMPT optimization criteria (or cost function) only includes dose-based objectives in which the relative biological effectiveness (RBE) is assumed to have a constant value of 1.1. In this study, we added LET-based objectives for maximizing LET in target volumes and minimizing LET in critical structures and normal tissues. Due to the fractional programming nature of the resulting model, we used a variable reformulation approach so that the optimization process is computationally equivalent to conventional IMPT optimization. In this study, five brain tumor patients who had been treated with proton therapy at our institution were selected. Two plans were created for each patient based on the proposed LET-incorporated optimization (LETOpt) and the conventional dose-based optimization (DoseOpt). The optimized plans were compared in terms of both dose (assuming a constant RBE of 1.1 as adopted in clinical practice) and LET. Both optimization approaches were able to generate comparable dose distributions. The LET-incorporated optimization achieved not only pronounced reduction of LET values in critical organs, such as brainstem and optic chiasm, but also increased LET in target volumes, compared to the conventional dose-based optimization. However, on occasion, there was a need to tradeoff the acceptability of dose and LET distributions. Our conclusion is that the inclusion of LET-dependent criteria in the IMPT optimization could lead to similar dose distributions as the conventional optimization but superior LET distributions in target volumes and normal tissues. This may have substantial advantages in improving tumor control and reducing normal tissue toxicities.

Dataset Information

Balancing benefits and limitations of linear energy transfer optimization in carbon ion radiotherapy for large sacral chordomas.

Background and purpose

Materials and methods

Results

Conclusion

Publications

Balancing benefits and limitations of linear energy transfer optimization in carbon ion radiotherapy for large sacral chordomas.

Similar Datasets

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