Magnetic resonance image-guided adaptive radiotherapy enables safe CTV-to-PTV margin reduction in prostate cancer: a cine MRI motion study.
Loading...
Embargo End Date
ICR Authors
Authors
Westley, RL
Alexander, SE
Goodwin, E
Dunlop, A
Nill, S
Oelfke, U
McNair, HA
Tree, AC
Alexander, SE
Goodwin, E
Dunlop, A
Nill, S
Oelfke, U
McNair, HA
Tree, AC
Document Type
Journal Article
Date
2024-06-04
Date Accepted
2024-04-29
Abstract
INTRODUCTION: We aimed to establish if stereotactic body radiotherapy to the prostate can be delivered safely using reduced clinical target volume (CTV) to planning target volume (PTV) margins on the 1.5T MR-Linac (MRL) (Elekta, Stockholm, Sweden), in the absence of gating. METHODS: Cine images taken in 3 orthogonal planes during the delivery of prostate SBRT with 36.25 Gray (Gy) in 5 fractions on the MRL were analysed. Using the data from 20 patients, the percentage of radiotherapy (RT) delivery time where the prostate position moved beyond 1, 2, 3, 4 and 5 mm in the left-right (LR), superior-inferior (SI), anterior-posterior (AP) and any direction was calculated. RESULTS: The prostate moved less than 3 mm in any direction for 90% of the monitoring period in 95% of patients. On a per-fraction basis, 93% of fractions displayed motion in all directions within 3 mm for 90% of the fraction delivery time. Recurring motion patterns were observed showing that the prostate moved with shallow drift (most common), transient excursions and persistent excursions during treatment. CONCLUSION: A 3 mm CTV-PTV margin is safe to use for the treatment of 5 fraction prostate SBRT on the MRL, without gating. In the context of gating this work suggests that treatment time will not be extensively lengthened when an appropriate gating window is applied.
Citation
Frontiers in Oncology, 2024, 14 pp. 1379596 -
Source Title
Frontiers in Oncology
Publisher
FRONTIERS MEDIA SA
ISSN
2234-943X
eISSN
2234-943X
2234-943X
2234-943X
Collections
Research Team
Radiother Phys Modelling