The impact of rectal spacers in MR-guided adaptive radiotherapy

Autor: Vikneswary Batumalai, David Crawford, Maddison Picton, Charles Tran, Urszula Jelen, Madeline Carr, Michael Jameson, Jeremy de Leon
Jazyk: angličtina
Rok vydání: 2024
Předmět:
Zdroj: Clinical and Translational Radiation Oncology, Vol 49, Iss , Pp 100872- (2024)
Druh dokumentu: article
ISSN: 2405-6308
DOI: 10.1016/j.ctro.2024.100872
Popis: Background and purpose: The use of stereotactic ablative radiotherapy (SABR) for prostate cancer has increased significantly. However, SABR can elevate the risk of moderate gastrointestinal (GI) side effects. Rectal spacers mitigate this risk by reducing the rectal dose. This study evaluates the impact of rectal spacers in MR-guided adaptive radiotherapy (MRgART) for prostate SABR. Materials and methods: A retrospective analysis was conducted on twenty patients with localised prostate cancer treated on the Unity MR-Linac at a single centre. Half of the cohort (n = 10) had rectal spacers placed before treatment. The adapt-to-shape strategy was used for online MRgART, and non-adapted plans were later generated offline for comparison. Dosimetric assessments were made between spacer and no-spacer cohorts, and between online adapted and non-adapted plans. Clinician-reported outcomes for genitourinary (GU) and GI toxicity were assessed at 3-, 6-, and 12-months post-treatment using Common Terminology Criteria for Adverse Events v.5.0. Results: No grade 2 or higher toxicity was observed in either cohort. Overall, the dosimetric analysis showed comparable results between the cohorts for target volumes, with D95% of 36.3 Gy in the spacer cohort and 36.0 Gy in the no-spacer cohort (p = 0.08). The spacer cohort demonstrated significant benefits in all rectal dose objectives (p
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