TY  - JOUR
AU  - Baltazar, Filipa
AU  - Longarino, Friderike K
AU  - Stengl, Christina
AU  - Liermann, Jakob
AU  - Mein, Stewart
AU  - Debus, Jürgen
AU  - Tessonnier, Thomas
AU  - Mairani, Andrea
TI  - Investigating LETd optimization strategies in carbon ion radiotherapy for pancreatic cancer: a dosimetric study using an anthropomorphic phantom.
JO  - Medical physics
VL  - 52
IS  - 3
SN  - 0094-2405
CY  - College Park, Md.
PB  - AAPM
M1  - DKFZ-2024-02632
SP  - 1746-1757
PY  - 2025
N1  - #EA:E050#LA:E210# / 2025 Mar;52(3):1746-1757
AB  - Clinical carbon ion beams offer the potential to overcome hypoxia-induced radioresistance in pancreatic tumors, due to their high dose-averaged Linear Energy Transfer (LETd), as previous studies have linked a minimum LETd within the tumor to improved local control. Current clinical practices at the Heidelberg Ion-Beam Therapy Center (HIT), which use two posterior beams, do not fully exploit the LETd advantage of carbon ions, as the high LETd is primarily focused on the beams' distal edges. Different LETd-boosting strategies, such as Spot-scanning Hadron Arc (SHArc), could enhance LETd distribution by concentrating high-LETd values in potential hypoxic tumor cores while sparing organs at risk.This study aims to investigate and verify different LETd-boosting strategies using an anthropomorphic pancreas phantom.Various LETd-boosting strategies were investigated for a cylindrical and a pancreas-shaped target in an anthropomorphic pancreas phantom. Treatment plans were optimized using single field optimization (SFO) or multi field optimization (MFO), with objective functions based on either physical dose (Phys), relative biological effectiveness (RBE)-weighted dose, or a combination of RBE and LETd-based objectives (LETopt). The LETd-boosting planning strategies were optimized with the goal of increasing the minimum LETd in the tumor without compromising its homogeneous dose coverage. Beam configurations investigated included the two-beam in-house clinical standard (2-SFOPhys, 2-SFORBE and 2-MFORBE-LETopt), a three-beam configuration (3-MFORBE and 3-MFORBE-LETopt) and SHArc (SHArcPhys, SHArcRBE and SHArcRBE-LETopt) using step-and-shoot delivery. The different plans were verified using an anthropomorphic pancreas phantom at HIT and compared to treatment planning system (TPS) predictions.All investigated LETd-boosting strategies altered the LETd distribution while meeting optimization goals and constraints, resulting in varying degrees of LETd enhancement. For the cylindrical volume, the SHArc plan resulted in the highest LETd concentration in the tumor core, with the minimum LETd in the GTV scaling up to 91 keV/µm. For the pancreas-shaped volume, however, the 3-MFORBE-LETopt achieved a higher minimum LETd in the GTV than SHArcRBE (75.6 and 62.3 keV/µm, respectively). When combining SHArc with LETd optimization, a minimum LETd of 76.3 keV/µm was achieved, suggesting a potential benefit from this combined approach. Most dosimetric verifications showed dose deviations to the TPS within a 5
KW  - LETd‐boosting (Other)
KW  - pancreatic cancer (Other)
KW  - spot‐scanning hadron arc (Other)
LB  - PUB:(DE-HGF)16
C6  - pmid:39656067
DO  - DOI:10.1002/mp.17569
UR  - https://inrepo02.dkfz.de/record/294925
ER  -