Dataset Information

A systematic review and meta-analysis of radiotherapy planning studies comparing multi leaf collimator designs.

ABSTRACT:

Background and purpose

Several studies have investigated multi leaf collimator (MLC) leaf design. We performed a systematic review and meta-analysis of those studies to compare the impact of MLC leaf width used for different radiotherapy techniques.

Materials and methods

We decided to focus on 2.5, 3.0 and 5.0?mm leaf width MLCs as it appeared to be the most contentious area from literature. We adopted Cochrane and PRISMA guidelines and computed the association between MLC leaf width and conformity index (CI) across the selected studies as pooled mean difference (PMD) with 95% confidence interval.

Results

A total of 43 papers were selected from the literature search, of which ten compare MLC leaf width of 2.5?mm or 3.0?mm (MLC2.5?mm) versus 5.0?mm (MLC5?mm) in terms of CI. There was a slight, but significant, difference between MLC2.5?mm and MLC5?mm in favor of the former (mean difference -0.036; 95% confidence interval: -0.068 to -0.005). A subgroup analysis was performed by comparing techniques (intensity modulated radiation therapy vs conformal). In the intensity modulated radiation therapy (IMRT) subgroup, the difference between MLC2.5?mm and MLC5?mm appeared to be negligible (mean difference: -0.006; 95% confidence interval: -0.013 to 0.001) and not significantly different from zero. In the subgroup of studies which used conformal techniques, there was a significant difference between MLC2.5?mm and MLC5?mm (mean difference: -0.054; 95% confidence interval: -0.096 to -0.012).

Conclusions

Introduction of IMRT produced comparable target coverage (CI) between 2.5 or 5.0?mm leaf width MLCs.

SUBMITTER: Luzzara M

PROVIDER: S-EPMC7807674 | biostudies-literature | 2018 Jan

REPOSITORIES: biostudies-literature

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Publications

A systematic review and meta-analysis of radiotherapy planning studies comparing multi leaf collimator designs.

Luzzara Marco M Santoro Luigi L Brown Kevin K

Physics and imaging in radiation oncology 20180101

<h4>Background and purpose</h4>Several studies have investigated multi leaf collimator (MLC) leaf design. We performed a systematic review and meta-analysis of those studies to compare the impact of MLC leaf width used for different radiotherapy techniques.<h4>Materials and methods</h4>We decided to focus on 2.5, 3.0 and 5.0 mm leaf width MLCs as it appeared to be the most contentious area from literature. We adopted Cochrane and PRISMA guidelines and computed the association between MLC leaf wi ...[more]

PMID: 33458375

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Project description:BackgroundThis study evaluated the dosimetric impact of various treatment techniques as well as collimator leaf width (2.5 vs 5 mm) for three groups of tumors -- spine tumors, brain tumors abutting the brainstem, and liver tumors. These lesions often present challenges in maximizing dose to target volumes without exceeding critical organ tolerance. Specifically, this study evaluated the dosimetric benefits of various techniques and collimator leaf sizes as a function of lesion size and shape.MethodsFifteen cases (5 for each site) were studied retrospectively. All lesions either abutted or were an integral part of critical structures (brainstem, liver or spinal cord). For brain and liver lesions, treatment plans using a 3D-conformal static technique (3D), dynamic conformal arcs (DARC) or intensity modulation (IMRT) were designed with a conventional linear accelerator with standard 5 mm leaf width multi-leaf collimator, and a linear accelerator dedicated for radiosurgery and hypofractionated therapy with a 2.5 mm leaf width collimator. For the concave spine lesions, intensity modulation was required to provide adequate conformality; hence, only IMRT plans were evaluated using either the standard or small leaf-width collimators.A total of 70 treatment plans were generated and each plan was individually optimized according to the technique employed. The Generalized Estimating Equation (GEE) was used to separate the impact of treatment technique from the MLC system on plan outcome, and t-tests were performed to evaluate statistical differences in target coverage and organ sparing between plans.ResultsThe lesions ranged in size from 2.6 to 12.5 cc, 17.5 to 153 cc, and 20.9 to 87.7 cc for the brain, liver, and spine groups, respectively. As a group, brain lesions were smaller than spine and liver lesions. While brain and liver lesions were primarily ellipsoidal, spine lesions were more complex in shape, as they were all concave. Therefore, the brain and the liver groups were compared for volume effect, and the liver and spine groups were compared for shape. For the brain and liver groups, both the radiosurgery MLC and the IMRT technique contributed to the dose sparing of organs-at-risk(OARs), as dose in the high-dose regions of these OARs was reduced up to 15%, compared to the non-IMRT techniques employing a 5 mm leaf-width collimator. Also, the dose reduction contributed by the fine leaf-width MLC decreased, as dose savings at all levels diminished from 4 - 11% for the brain group to 1 - 5% for the liver group, as the target structures decreased in volume. The fine leaf-width collimator significantly improved spinal cord sparing, with dose reductions of 14 - 19% in high to middle dose regions, compared to the 5 mm leaf width collimator.ConclusionThe fine leaf-width MLC in combination with the IMRT technique can yield dosimetric benefits in radiosurgery and hypofractionated radiotherapy. Treatment of small lesions in cases involving complex target/OAR geometry will especially benefit from use of a fine leaf-width MLC and the use of IMRT.

Project description:PurposeThe role of concurrent chemoradiotherapy (CCRT) in stage II nasopharyngeal carcinoma (NPC) is still controversial. Our objective is to evaluate the value of concurrent chemotherapy in stage II NPC receiving radiotherapy (RT).MethodsWe searched the PubMed, Embase, and Scopus databases for studies comparing CCRT versus RT alone in stage II NPC with survival outcomes and toxicities, including locoregional recurrence-free survival (LRFS), metastasis-free survival (DMFS), progression-free survival (PFS), overall survival (OS), and grade 3-4 acute toxicities. The hazard ratios (HRs) of survival outcomes and risk ratios (RRs) of toxicities were extracted for meta-analysis. Subgroup analysis for stage N1 patients was performed to further explore whether these populations can earn benefits from concurrent chemotherapy.ResultsNine eligible studies with a total of 4,092 patients were included. CCRT was associated with a better OS (HR = 0.61, 95% CI 0.44-0.82), LRFS (HR = 0.62, 95% CI 0.50-0.78), and PFS (HR = 0.65, 95% CI 0.54-0.79), but with similar DMFS (HR = 0.81, 95% CI = 0.46-1.45) compared with two-dimensional RT (2DRT) alone. However, CCRT showed no survival benefit in terms of OS (HR = 0.84, 95% CI 0.62-1.15), LRFS (HR = 0.85, 95% CI 0.54-1.34), DMFS (HR = 0.96, 95% CI 0.60-1.54), and PFS (HR = 0.96, 95% CI 0.66-1.37) compared with intensity-modulated RT (IMRT) alone. Subgroup analyses indicated that CCRT had similar OS (HR = 1.04, 95% CI 0.37-2.96), LRFS (HR = 0.70, 95% CI 0.34-1.45), DMFS (HR = 1.03, 95% CI 0.53-2.00), and PFS (HR = 1.04, 95% CI 0.58-1.88) in the stage N1 populations. Meanwhile, compared to RT alone, CCRT significantly increased the incidence of grade 3-4 leukopenia (RR = 4.00, 95% CI 2.29-6.97), mucositis (RR = 1.43, 95% CI 1.16-1.77), and gastrointestinal reactions (RR = 8.76, 95% CI 2.63-29.12). No significant differences of grade 3-4 toxicity in thrombocytopenia (RR = 3.45, 95% CI 0.85-13.94) was found between the two groups.ConclusionFor unselected patients with stage II NPC, CCRT was superior to 2DRT alone with better LRFS, PFS, and OS, while adding concurrent chemotherapy to IMRT did not significantly improve survival but exacerbated acute toxicities.Systematic review registrationhttps://www.crd.york.ac.uk/PROSPERO/, identifier CRD42022318253.

Project description:Availability of a single source review of once-daily fixed-dose single tablet regimen (STR) and multiple tablet fixed-dose regimen (MTR) would optimally inform healthcare providers and policy makers involved in the management of population with human immunodeficiency virus (HIV).We conducted a meta-analysis of published literature to compare patient adherence, clinical, and cost outcomes of STR to MTR.Published literature in English between 2005 and 2014 was searched using Embase, PubMed (Medline in-process), and ClinicalTrials.Gov databases. Two-level screening was undertaken by 2 independent researchers to finalize articles for evidence synthesis. Adherence, efficacy, safety, tolerability, healthcare resource use (HRU), and costs were assessed comparing STR to MTR. A random-effects meta-analysis was performed and heterogeneity examined using meta-regression.Thirty-five articles were identified for qualitative evidence synthesis, of which 9 had quantifiable data for meta-analysis (4 randomized controlled trials and 5 observational studies). Patients on STR were significantly more adherent when compared to patients on MTR of any frequency (odds ratio [OR]: 2.37 [95% CI: 1.68, 3.35], P < 0.001; 4 studies), twice-daily MTR (OR: 2.53 [95% CI: 1.13, 5.66], P = 0.02; 2 studies), and once-daily MTR (OR: 1.81 [95% CI: 1.15, 2.84], P = 0.01; 2 studies). The relative risk (RR) for viral load suppression at 48 weeks was higher (RR: 1.09 [95% CI: 1.04, 1.15], P = .0003; 3 studies) while RR of grade 3 to 4 laboratory abnormalities was lower among patients on STR (RR: 0.68 [95% CI: 0.49, 0.94], P = 0.02; 2 studies). Changes in CD4 count at 48 weeks, any severe adverse events (SAEs), grade 3 to 4 AEs, mortality, and tolerability were found comparable between STR and MTR. Several studies reported significant reduction in HRU and costs among STR group versus MTR.Study depicted comparable tolerability, safety (All-SAE and Grade 3-4 AE), and mortality and fewer Grade 3 to 4 lab abnormalities and better viral load suppression and adherence among patients on FDC-containing STR versus MTR; literature depicted favorable HRU and costs for STRs.These findings may help decision makers especially in resource-poor settings to plan for optimal HIV disease management when the choice of both STRs and MTRs are available.

Dataset Information

A systematic review and meta-analysis of radiotherapy planning studies comparing multi leaf collimator designs.

Background and purpose

Materials and methods

Results

Conclusions

Publications

A systematic review and meta-analysis of radiotherapy planning studies comparing multi leaf collimator designs.

Similar Datasets

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