Interpretation of PlanIQ-derived feasibility dose-volume histogram f-values in lung SBRT with heterogeneous dose distributions.

Authors

Mayuka Kamada, Motoharu Sasaki, Yuji Nakaguchi, Takeshi Kamomae, Yuki Kanazawa, Yuto Yamaji, Kanako Sakuragawa, Akira Tsuzuki, Ryosuke Kasai, Hitoshi Ikushima

Published in

Medical dosimetry : official journal of the American Association of Medical Dosimetrists. Oct 15, 2026. Epub Oct 15, 2026.

Abstract

Feasibility dose-volume histogram (FDVH) analysis estimates patient-specific organ-at-risk dose-reduction feasibility, but the interpretation of FDVH-derived f-values in lung stereotactic body radiotherapy (SBRT) with heterogeneous target dosing remains unclear. This study evaluated FDVH-derived f-values in 25 peripheral lung cancer cases planned with VMAT-based SBRT. Plans were prescribed to 50 Gy in 4 fractions and normalized so that planning target volume (PTV) D95% corresponded to the prescription dose, while allowing target heterogeneity with PTV D2% of approximately 135% to 145% of the prescription dose. FDVH analysis was performed using PlanIQ under 2 conditions: Condition A used the clinical prescription dose, and Condition B used adjusted target reference doses derived from the mean minimum doses to the gross tumor volume (GTV) and PTV excluding the GTV (PTV-GTV). FDVH-derived f-values were evaluated for the ipsilateral normal lung and optimization Ring ROIs, and cases classified as the Impossible region (f = 0) were analyzed separately. For the ipsilateral normal lung, 6, 17, and 9 cases were classified as the Impossible region under Condition A for V10 Gy, V20 Gy, and mean lung dose, respectively; the corresponding numbers under Condition B were 5, 14, and 9. For the Ring ROIs, f-values were obtained for all cases under Condition B, with the highest median f-value observed for Ring 2 under both conditions. These findings suggest that FDVH estimates may not fully correspond to clinical dose distributions in lung SBRT with heterogeneous target dosing. FDVH-derived f-values should be interpreted with consideration of target dose heterogeneity and dose fall-off.

PMID:
42881033
Bibliographic data and abstract were imported from PubMed on 16 Oct 2026.

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