PurposeTo quantify the difference in accuracy of adapt-to-position (ATP), adapt-to-rotation (ATR) and adapt-to-shape (ATS) workflows used in MRI-guided online adaptive radiotherapy for prostate... Show morePurposeTo quantify the difference in accuracy of adapt-to-position (ATP), adapt-to-rotation (ATR) and adapt-to-shape (ATS) workflows used in MRI-guided online adaptive radiotherapy for prostate carcinoma (PCa) by evaluating the margins required to accommodate intra-fraction motion of the clinical target volumes for prostate (CTVpros), prostate including seminal vesicles (CTVpros + sv) and gross tumor volume (GTV).Materials and methodsClinical delineations of the CTVpros, CTVpros + sv and GTV of 24 patients with intermediate- and high-risk PCa, treated using ATS on a 1.5 T MR-Linac, were used for analysis. Delineations were available pre- and during beam-on. To simulate ATP and ATR workflows, we automatically generated the structures associated with these workflows using rigid transformations from the planning-MRI to the daily online MRIs. Clinical GTVs were analyzed as ATR GTVs and only ATP GTVs were simulated. Planning target volumes (PTVs) were generated with isotropic margins ranging 0.0–5.0 mm. The volumetric overlap was calculated between these PTVs and their corresponding clinical delineation on the MRI acquired during beam-on and averaged over all treatment fractions.ResultsThe PTV margin required to cover > 95% of the CTVpros was equal (2.5 mm) for all workflows. For the CTVpros + sv, this margin increased to 5.0, 4.0 and 3.5 mm in the ATP, ATR and ATS workflow, respectively. GTV coverage improved from ATP to ATR for margins up to 4.0 mm.ConclusionATP, ATR and ATS workflows ensure equal coverage of the CTVpros for the current clinical margins. For the CTVpros + sv, ATS showed optimal performance. GTV coverage improves by additional adaptations to prostate rotations. Show less
Groen, V.H.; Schie, M. van; Zuithoff, N.P.A.; Monninkhof, E.M.; Kunze-Busch, M.; Boer, J.C.J. de; ... ; Kerkmeijer, L.G.W. 2022
Purpose or objectives: The FLAME trial (NCT01168479) showed that by adding a focal boost to conventional fractionated EBRT in the treatment of localized prostate cancer, the five-year biochemical... Show morePurpose or objectives: The FLAME trial (NCT01168479) showed that by adding a focal boost to conventional fractionated EBRT in the treatment of localized prostate cancer, the five-year biochemical disease-free survival increased, without significantly increasing toxicity. The aim of the present study was to investigate the association between radiation dose to the bladder and urethra and genitourinary (GU) toxicity grade >= 2 in the entire cohort.Material and methods: The dose-effect relations of the urethra and bladder dose, separately, and GU toxicity grade >= 2 (CTCAE 3.0) up to five years after treatment were assessed. A mixed model analysis for repeated measurements was used, adjusting for age, diabetes mellitus, T-stage, baseline GU toxicity grade >= 1 and institute. Additionally, the association between the dose and separate GU toxicity subdomains were investigated.Results: Dose-effect relations were observed for the dose (Gy) to the bladder D2 cm(3) and urethra D0.1 cm(3), with adjusted odds ratios of 1.14 (95% CI 1.12-1.16, p < 0.0001) and 1.12 (95% CI 1.11-1.14, p < 0.0001), respectively. Additionally, associations between the dose to the urethra and bladder and the subdomains urinary frequency, urinary retention and urinary incontinence were observed.Conclusion: Further increasing the dose to the bladder and urethra will result in a significant increase in GU toxicity following EBRT. Focal boost treatment plans should incorporate a urethral dose-constraint. Further treatment optimization to increase the focal boost dose without increasing the dose to the urethra and other organs at risk should be a focus for future research, as we have shown that a focal boost is beneficial in the treatment of prostate cancer. (C) 2021 The Author(s). Published by Elsevier B.V. Show less
Schie, M.A. van; Dinh, C.V.; Houdt, P.J. van; Pos, F.J.; Heijmink, S.W.T.J.P.; Kerkmeijer, L.G.W.; ... ; Heide, U.A. van der 2018
