Comparing biological effectiveness guided plan optimization strategies for cranial proton therapy: potential and challenges

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dc.contributor.authorHahn, Christian
dc.contributor.authorHeuchel, Lena
dc.contributor.authorÖdén, Jakob
dc.contributor.authorTraneus, Erik
dc.contributor.authorWulff, Jörg
dc.contributor.authorPlaude, Sandija
dc.contributor.authorTimmermann, Beate
dc.contributor.authorBäumer, Christian
dc.contributor.authorLühr, Armin
dc.date.accessioned2023-02-17T08:00:38Z
dc.date.available2023-02-17T08:00:38Z
dc.date.issued2022-10-22
dc.description.abstractBackground: To introduce and compare multiple biological effectiveness guided (BG) proton plan optimization strategies minimizing variable relative biological effectiveness (RBE) induced dose burden in organs at risk (OAR) while maintaining plan quality with a constant RBE. Methods: Dose-optimized (DOSEopt) proton pencil beam scanning reference treatment plans were generated for ten cranial patients with prescription doses ≥ 54 Gy(RBE) and ≥ 1 OAR close to the clinical target volume (CTV). For each patient, four additional BG plans were created. BG objectives minimized either proton track-ends, dose-averaged linear energy transfer (LETd), energy depositions from high-LET protons or variable RBE-weighted dose (DRBE) in adjacent serially structured OARs. Plan quality (RBE = 1.1) was assessed by CTV dose coverage and robustness (2 mm setup, 3.5% density), dose homogeneity and conformity in the planning target volumes and adherence to OAR tolerance doses. LETd, DRBE (Wedenberg model, α/βCTV = 10 Gy, α/βOAR = 2 Gy) and resulting normal tissue complication probabilities (NTCPs) for blindness and brainstem necrosis were derived. Differences between DOSEopt and BG optimized plans were assessed and statistically tested (Wilcoxon signed rank, α = 0.05). Results: All plans were clinically acceptable. DOSEopt and BG optimized plans were comparable in target volume coverage, homogeneity and conformity. For recalculated DRBE in all patients, all BG plans significantly reduced near-maximum DRBE to critical OARs with differences up to 8.2 Gy(RBE) (p < 0.05). Direct DRBE optimization primarily reduced absorbed dose in OARs (average ΔDmean = 2.0 Gy; average ΔLETd,mean = 0.1 keV/µm), while the other strategies reduced LETd (average ΔDmean < 0.3 Gy; average ΔLETd,mean = 0.5 keV/µm). LET-optimizing strategies were more robust against range and setup uncertaintes for high-dose CTVs than DRBE optimization. All BG strategies reduced NTCP for brainstem necrosis and blindness on average by 47% with average and maximum reductions of 5.4 and 18.4 percentage points, respectively. Conclusions: All BG strategies reduced variable RBE-induced NTCPs to OARs. Reducing LETd in high-dose voxels may be favourable due to its adherence to current dose reporting and maintenance of clinical plan quality and the availability of reported LETd and dose levels from clinical toxicity reports after cranial proton therapy. These optimization strategies beyond dose may be a first step towards safely translating variable RBE optimization in the clinics.en
dc.identifier.urihttp://hdl.handle.net/2003/41246
dc.identifier.urihttp://dx.doi.org/10.17877/DE290R-23087
dc.language.isoende
dc.relation.ispartofseriesRadiation oncology;17
dc.rights.urihttps://creativecommons.org/licenses/by/4.0/
dc.subjectProton therapyen
dc.subjectTreatment plan optimizationen
dc.subjectLinear energy transfer (LET)en
dc.subjectRelative biological effectiveness (RBE)en
dc.subjectTrack endsen
dc.subjectDirty doseen
dc.subject.ddc530
dc.titleComparing biological effectiveness guided plan optimization strategies for cranial proton therapy: potential and challengesen
dc.typeTextde
dc.type.publicationtypearticlede
dcterms.accessRightsopen access
eldorado.secondarypublicationtruede
eldorado.secondarypublication.primarycitationHahn, C., Heuchel, L., Ödén, J. et al. Comparing biological effectiveness guided plan optimization strategies for cranial proton therapy: potential and challenges. Radiat Oncol 17, 169 (2022). https://doi.org/10.1186/s13014-022-02143-xde
eldorado.secondarypublication.primaryidentifierDOI https://doi.org/10.1186/s13014-022-02143-xde

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