Ödén, J., Eriksson, K., Svensson, S. et al. (6 more authors) (2024) Technical note: Optimization functions for re‐irradiation treatment planning. Medical Physics, 51 (1). pp. 476-484. ISSN 0094-2405
Abstract
Background Although re-irradiation is increasingly used in clinical practice, almost no dedicated planning software exists.
Purpose Standard dose-based optimization functions were adjusted for re-irradiation planning using accumulated equivalent dose in 2-Gy fractions (EQD2) with rigid or deformable dose mapping, tissue-specific α/β, treatment-specific recovery coefficients, and voxelwise adjusted EQD2 penalization levels based on the estimated previously delivered EQD2 (EQD2deliv).
Methods To demonstrate proof-of-concept, 35 Gy in 5 fractions was planned to a fictitious spherical relapse planning target volume (PTV) in three separate locations following previous prostate treatment on a virtual human phantom. The PTV locations represented one repeated irradiation scenario and two re-irradiation scenarios. For each scenario, three re-planning strategies with identical PTV dose-functions but various organ at risk (OAR) EQD2-functions was used: 1) reRTregular: Regular functions with fixed EQD2 penalization levels larger than EQD2deliv for all OAR voxels.
2) reRTreduce: As reRTregular, but with lower fixed EQD2 penalization levels aiming to reduce OAR EQD2.
3) reRTvoxelwise: As reRTregular and reRTreduce, but with voxelwise adjusted EQD2 penalization levels based on EQD2deliv.
PTV near-minimum and near-maximum dose (D98%/D2%), homogeneity index (HI), conformity index (CI) and accumulated OAR EQD2 (α/β = 3 Gy) were evaluated. Results For the repeated irradiation scenario, all strategies resulted in similar dose distributions. For the re-irradiation scenarios, reRTreduce and reRTvoxelwise reduced accumulated average and near-maximum EQD2 by ˜1–10 Gy for all relevant OARs compared to reRTregular. The reduced OAR doses for reRTreduce came at the cost of distorted dose distributions with D98% = 92.3%, HI = 12.0%, CI = 73.7% and normal tissue hot spots ≥150% for the most complex scenario, while reRTregular (D98% = 98.1%, HI = 3.2%, CI = 94.2%) and reRTvoxelwise (D98% = 96.9%, HI = 6.1%, CI = 93.7%) fulfilled PTV coverage without hot spots.
Conclusions The proposed re-irradiation-specific EQD2-based optimization functions introduce novel planning possibilities with flexible options to guide the trade-off between target coverage and OAR sparing with voxelwise adapted penalization levels based on EQD2deliv.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2023 American Association of Physicists in Medicine. This is the peer reviewed version of the following article: Ödén, J., Eriksson, K., Svensson, S. et al. (6 more authors) (2024) Technical note: Optimization functions for re‐irradiation treatment planning. Medical Physics, 51 (1). pp. 476-484. ISSN 0094-2405, which has been published in final form at https://doi.org/10.1002/mp.16815. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. This article may not be enhanced, enriched or otherwise transformed into a derivative work, without express permission from Wiley or by statutory rights under applicable legislation. Copyright notices must not be removed, obscured or modified. The article must be linked to Wiley’s version of record on Wiley Online Library and any embedding, framing or otherwise making available the article or pages thereof by third parties from platforms, services and websites other than Wiley Online Library must be prohibited. |
Keywords: | equivalent dose; optimization functions; re-irradiation |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Medicine and Health (Leeds) > School of Medicine (Leeds) > Leeds Institute of Medical Research (LIMR) > Division of Oncology |
Depositing User: | Symplectic Publications |
Date Deposited: | 25 Jan 2024 14:55 |
Last Modified: | 03 Nov 2024 01:13 |
Status: | Published |
Publisher: | Wiley |
Identification Number: | 10.1002/mp.16815 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:208225 |