Treatment plan optimisation for reirradiation

Murray, Louise; Thompson, Christopher; Pagett, Christopher; Lilley, J.; Al-Qaiseh, Bashar; Svensson, Stina; Eriksson, Kjell; Nix, Michael; Aldred, Michael J.; Aspin, L.; Gregory, Stephen; Appelt, Ane L

doi:10.1016/j.radonc.2023.109545

Cited by 9 publications

(24 citation statements)

References 25 publications

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“…The use of EQD2 allows for dose summation of radiotherapy courses with different fractionation schedules and is often used for dose summations in re-irradiation treatments. 1,[3][4][5]10…”

Section: Re-irradiation Optimization Functionsmentioning

confidence: 99%

“…The implementation here supports both rigid and DIR for dose mapping. [3][4][5] Note that the previously delivered dose from course j in Equation ( 2) can be estimated in various ways including the planned dose, dose-tracking on daily images, etc., and is always mapped to the re-irradiation CT before voxel-by-voxel conversion to EQD2 deliv, j with region of interest (ROI)-specific α/β ratios and ROI and treatment course specific recovery coefficients. Note also that the re-irradiation optimization function methodology presented in this study is conceptually invariant to the methodology used for dose accumulation.…”

Section: Dose Accumulationmentioning

confidence: 99%

“…These include the need to retrieve accurate image and dose data, handling of anatomical changes between the radiotherapy courses, integration of radiobiology when summing multiple radiotherapy courses, and deciding on clinically relevant dose constraints. [3][4][5][6][7][8] In contrast, almost no planning software specifically designed for re-irradiation exists, and even fewer efforts have been made on creating re-irradiation-specific optimization functions.Instead,various approaches requiring multiple manual steps for dose extraction and dose summation are often used. 4,7 Slightly more complex planning methods also exist where radiobiologically meaningful approaches are employed using, for example, the biological effective dose or the equivalent dose in 2-Gy fractions (EQD2).…”

Section: Introductionmentioning

confidence: 99%

“…[3][4][5][6][7][8] In contrast, almost no planning software specifically designed for re-irradiation exists, and even fewer efforts have been made on creating re-irradiation-specific optimization functions.Instead,various approaches requiring multiple manual steps for dose extraction and dose summation are often used. 4,7 Slightly more complex planning methods also exist where radiobiologically meaningful approaches are employed using, for example, the biological effective dose or the equivalent dose in 2-Gy fractions (EQD2). 9 Recent studies within the Support Tool for Re-Irradiation Decisions guided by Radiobiology (STRIDeR) project have, however, addressed some of these re-irradiation-specific planning issues including early versions of the optimization functions presented here, which act on the 3D distribution of the accumulated EQD2.…”

Section: Introductionmentioning

confidence: 99%

“…9 Recent studies within the Support Tool for Re-Irradiation Decisions guided by Radiobiology (STRIDeR) project have, however, addressed some of these re-irradiation-specific planning issues including early versions of the optimization functions presented here, which act on the 3D distribution of the accumulated EQD2. [3][4][5] Beyond acting on radiobiologically meaningful doses, other key issues when using standard optimization functions in re-irradiation planning are the lack of accounting for tissue recovery between treatment courses, and the use of penalization dose levels without accounting for the estimated previously delivered EQD2 (EQD2 deliv ). In particular, the latter is an issue in situations where the previously delivered dose in a voxel is similar to or higher than the requested total EQD2 level, which might cause misbehavior in the optimization as very low, or even negative, voxel doses are requested.…”

Section: Introductionmentioning

confidence: 99%

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Technical note: Optimization functions for re‐irradiation treatment planning

Ödén,

Eriksson,

Svensson

et al. 2023

Medical Physics

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BackgroundAlthough re‐irradiation is increasingly used in clinical practice, almost no dedicated planning software exists.PurposeStandard 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).MethodsTo 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: reRTregular: Regular functions with fixed EQD2 penalization levels larger than EQD2deliv for all OAR voxels. reRTreduce: As reRTregular, but with lower fixed EQD2 penalization levels aiming to reduce OAR EQD2. 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.ResultsFor 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.ConclusionsThe 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.

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“…The use of EQD2 allows for dose summation of radiotherapy courses with different fractionation schedules and is often used for dose summations in re-irradiation treatments. 1,[3][4][5]10…”

Section: Re-irradiation Optimization Functionsmentioning

confidence: 99%

Section: Dose Accumulationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Technical note: Optimization functions for re‐irradiation treatment planning

Ödén,

Eriksson,

Svensson

et al. 2023

Medical Physics

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Re-irradiation spine stereotactic body radiotherapy following high-dose conventional radiotherapy for metastatic epidural spinal cord compression: a retrospective study

Koide,

Haimoto,

Shimizu

et al. 2024

Jpn J Radiol

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Purpose We aimed to evaluate the efficacy and safety of re-irradiation stereotactic body radiation therapy (SBRT) in patients with metastatic epidural spinal cord compression (MESCC) following high-dose conventional radiotherapy. Materials and methods Twenty-one patients met the following eligibility criteria: with an irradiation history of 50 Gy2 equivalent dose in 2-Gy fractions (EQD2) or more, diagnosed MESCC in the cervical or thoracic spines, and treated with re-irradiation SBRT of 24 Gy in 2 fractions between April 2018 and March 2023. Prior treatment was radiotherapy alone, not including surgery. The primary endpoint was a 1-year local failure rate. Overall survival (OS) and treatment-related adverse events were assessed as the secondary endpoints. Since our cohort includes one treatment-related death (TRD) of esophageal perforation, the cumulative esophageal dose was evaluated to find the dose constraints related to severe toxicities. Results The median age was 68, and 14 males were included. The primary tumor sites (esophagus/lung/head and neck/others) were 6/6/7/2, and the median initial radiotherapy dose was 60 Gy2 EQD2 (range: 50–105 Gy2, 60–70/ > 70 Gy2 were 11/4). Ten patients underwent surgery followed by SBRT and 11 SBRT alone. At the median follow-up time of 10.4 months, 17 patients died of systemic disease progression including one TRD. No radiation-induced myelopathy or nerve root injuries occurred. Local failure occurred in six patients, with a 1-year local failure rate of 29.3% and a 1-year OS of 55.0%. Other toxicities included five cases of vertebral compression fractures (23.8%) and one radiation pneumonitis. The cumulative esophageal dose was recommended as follows: Dmax < 203, D0.035 cc < 187, and D1cc < 167 (Gy3 in biological effective dose). Conclusion Re-irradiation spine SBRT may be effective for selected patients with cervical or thoracic MESCC, even with high-dose irradiation histories. The cumulative dose assessment across the original and re-irradiated esophagus was recommended to decrease the risk of severe esophageal toxicities.

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