ArticleJournal of applied clinical medical physics2026
Strategies for enhancing delivery efficiency on MR-Linac: A dosimetric study and historical plan review.
Article in Journal of applied clinical medical physics, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.
What it found
Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.
The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
0 citing papers in PubMed.
No citing paper in PubMed yet.
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
8 authors.
Funding
No grant is acknowledged in the PubMed record.
Abstract
purposeThe Elekta Unity MR-Linac enables online adaptive radiotherapy (oART) with integrated 1.5T MRI. Given its relatively low dose rate, identifying optimal IMRT planning parameters is essential to achieve efficient delivery. This study investigates parameter optimization strategies that enhance delivery efficiency while maintaining high dosimetric quality.
methodsA dosimetric study was designed using ten prostate simultaneous integrated boost (SIB) patients (45 Gy/40 Gy in five fractions) and 10 liver SBRT patients (42-54 Gy in 3-5 fractions). Each patient has three plans: (1) Clinical, (2) Refa (segment-limited, ≤120 segments), and (3) Refb (MU-modulated plan with larger minimum segment width (0.7 cm or 1 cm) and higher fluence map smoothing level (medium or high)). A linear equation for estimating delivery time was established and validated against 1173 retrospective Unity plans based on total segments and Monitor Units (MUs). All the study plans were evaluated by comparing delivery efficiency related metrics (total number of segments, MUs, estimated delivery time), and plan quality using dose-volume histogram (DVH) metrics for targets and organs-at-risk (OARs). Additionally, an online adaptive study was performed on representative cases: the three reference plans were adapted to a daily image, and the resulting adaptive plans were assessed for optimization time and plan quality against clinical criteria.
resultsUsing the derived delivery time estimation equation on 173 unseen test cases, the mean absolute error (MAE) between estimated and recorded times was 0.9 min, with 84% of cases with a prediction error within ±1 min, and with 95% of cases falling within ±2 min. Both strategies reduced delivery complexity compared with clinical plans. For prostate cases, Refa and Refb lowered segment counts to <120 (vs. original 137-178) and reduced MUs from 3022 to 2899 (Refa) and 2497 (Refb), respectively. Delivery times decreased on average by 2.6 min with Refa (up to 5.4) and 4.0 min with Refb (up to 6.7). For liver cases, segment counts dropped from (149-198) to <120, with mean MUs reduced from 4233 to 3528 (Refa) and 3309 (Refb). Delivery times were shortened from 24.4 min to 18.9 (Refa) and 18.3 (Refb), up to 7.6 min saving for Refa and up to 8.9 min for Refb. Across both cohorts, PTV coverage and OAR sparing were maintained, with no statistically significant differences (p > 0.05). All adaptive plans from Refa and Refb were completed within 5-13 min, consistent with standard clinical online optimization times. After normalization to the clinical adaptive plan, all plans met the dosimetric goals. A similar time-saving trend was observed across the adaptive plans.
conclusionsSystematic adjustment of Unity IMRT planning parameters-specifically limiting total segment number, reasonable minimum segment width, and fluence smoothing-can markedly improve delivery efficiency while maintaining clinically acceptable dosimetric quality. These findings provide practical, evidence-based guidelines for parameter selection in Unity planning, supporting reduced treatment times, improved patient throughput, and broader clinical feasibility of MR-guided online adaptive radiotherapy.
Indexed as
Identifiers
What OpenQuestion holds
Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.