Comparing adaptation strategies in MRI-guided online adaptive radiotherapy for prostate cancer: Implications for treatment margins

Dassen, M.; Janssen, Tomas; Kusters, Martijn; Pos, Floris J.; Kerkmeijer, Linda G.W.; Heide, Uulke A. van der; Bijl, Erik van der

doi:10.1016/j.radonc.2023.109761

Cited by 4 publications

(1 citation statement)

References 33 publications

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“…In a recent analysis with 26 patients with localized prostate cancer, Dassen et al. compared radiation plans with separate adaptation strategies for position, rotation and shape in MR-guided online adaptive SBRT, concluding that a PTV margin reduction is probably safe in patients with inclusion of (parts of) the seminal vesicles, but not in cases of prostate-only irradiation ( 23 ). The presented dataset, illustrating the 10 th to 90 th percentile range of target volume coverage and OAR overlap, suggests variations among the plans in a similar range as presented in our study: Some radiation plans easily achieve target volume goals and OAR constraints, while others (at the lower end of the trajectories and below) may especially benefit from adaptation.…”

Section: Discussionmentioning

confidence: 99%

Dosimetric benefit of online treatment plan adaptation in stereotactic ultrahypofractionated MR-guided radiotherapy for localized prostate cancer

Fink,

Buchele,

Baumann

et al. 2024

Front. Oncol.

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BackgroundApart from superior soft tissue contrast, MR-guided stereotactic body radiation therapy (SBRT) offers the chance for daily online plan adaptation. This study reports on the comparison of dose parameters before and after online plan adaptation in MR-guided SBRT of localized prostate cancer.Materials and methods32 consecutive patients treated with ultrahypofractionated SBRT for localized prostate cancer within the prospective SMILE trial underwent a planning process for MR-guided radiotherapy with 37.5 Gy applied in 5 fractions. A base plan, derived from MRI simulation at an MRIdian Linac, was registered to daily MRI scans (predicted plan). Following target and OAR recontouring, the plan was reoptimized based on the daily anatomy (adapted plan). CTV and PTV coverage and doses at OAR were compared between predicted and adapted plans using linear mixed regression models.ResultsIn 152 out of 160 fractions (95%), an adapted radiation plan was delivered. Mean CTV and PTV coverage increased by 1.4% and 4.5% after adaptation. 18% vs. 95% of the plans had a PTV coverage ≥95% before and after online adaptation, respectively. 78% vs. 100% of the plans had a CTV coverage ≥98% before and after online adaptation, respectively. The D0.2cc for both bladder and rectum were <38.5 Gy in 93% vs. 100% before and after online adaptation. The constraint at the urethra with a dose of <37.5 Gy was achieved in 59% vs. 93% before and after online adaptation.ConclusionOnline adaptive plan adaptation improves target volume coverage and reduces doses to OAR in MR-guided SBRT of localized prostate cancer. Online plan adaptation could potentially further reduce acute and long-term side effects and improve local failure rates in MR-guided SBRT of localized prostate cancer.

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Section: Discussionmentioning

confidence: 99%