The effect of multileaf collimator leaf width on the radiosurgery planning for spine lesion treatment in terms of the modulated techniques and target complexity

Chae, Soo-Min; Lee, Gi Woong; Son, Seung Hyun

doi:10.1186/1748-717x-9-72

Cited by 27 publications

(24 citation statements)

References 42 publications

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“…Chae et al found that for artificially contoured spine lesions, the HD‐MLC significantly improved GI but not CI, but that the results more notable for IMRT vs VMAT. The biggest gains were seen for complex target shapes 7. Tanyi et al performed a planning study comparing the M120 to HD‐MLC for liver and lung with 3D, IMRT, and VMAT treatment plans and found small differences between the MLC types with the biggest difference being the faster dose falloff with the HD‐MLC 8.…”

Section: Discussionmentioning

confidence: 99%

The impact of a high‐definition multileaf collimator for spine SBRT

Younge

Kuchta

Mikell

et al. 2017

J Applied Clin Med Phys

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PurposeAdvanced radiotherapy delivery systems designed for high‐dose, high‐precision treatments often come equipped with high‐definition multi‐leaf collimators (HD‐MLC) aimed at more finely shaping radiation dose to the target. In this work, we study the effect of a high definition MLC on spine stereotactic body radiation therapy (SBRT) treatment plan quality and plan deliverability.Methods and MaterialsSeventeen spine SBRT cases were planned with VMAT using a standard definition MLC (M120), HD‐MLC, and HD‐MLC with an added objective to reduce monitor units (MU). M120 plans were converted into plans deliverable on an HD‐MLC using in‐house software. Plan quality and plan deliverability as measured by portal dosimetry were compared among the three types of plans.ResultsOnly minor differences were noted in plan quality between the M120 and HD‐MLC plans. Plans generated with the HD‐MLC tended to have better spinal cord sparing (3% reduction in maximum cord dose). HD‐MLC plans on average had 12% more MU and 55% greater modulation complexity as defined by an in‐house metric. HD‐MLC plans also had significantly degraded deliverability. Of the VMAT arcs measured, 94% had lower gamma passing metrics when using the HD‐MLC.ConclusionModest improvements in plan quality were noted when switching from M120 to HD‐MLC at the expense of significantly less accurate deliverability in some cases.

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Section: Discussionmentioning

confidence: 99%

The impact of a high‐definition multileaf collimator for spine SBRT

Younge

Kuchta

Mikell

et al. 2017

J Applied Clin Med Phys

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“…The downsizing effect of MLC leaf width has predominantly been reported for 3DCRT, DCAT, and IMRT. There have only been a few reports concerning the downsizing effect of MLC leaf width in VMAT [10, 29, 30]. Our previous study regarding the downsizing effect of MLC leaf width in spinal radiosurgery revealed that TVC improved by 8.38% and 2.97% in IMRT and VMAT, respectively, and the effect was smaller with VMAT than with IMRT [10].…”

Section: Discussionmentioning

confidence: 99%

“…Therefore, changing the sophisticated grade within the same technique is necessary in order to evaluate the change of the downsizing effect of MLC leaf width according to the sophisticated grade of technique. In addition, there have been several reports indicating that the downsizing effect of MLC leaf width differs according to the complexity of the target shape [4, 8–10]. Thus, to reduce this kind of bias, relatively simple shapes should be selected for evaluation with respect to the target volume.…”

Section: Introductionmentioning

confidence: 99%

Dosimetric impact of multileaf collimator leaf width according to sophisticated grade of technique in the IMRT and VMAT planning for pituitary adenoma lesion

2016

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We analyzed the difference in the dosimetric effect between 5-mm and 2.5-mm multileaf collimator (MLC) leaf width according to the sophisticated grades of intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT). Nineteen patients with pituitary adenomas were selected for this study. The treatment plans were performed according to the size of the MLC (5-mm and 2.5-mm MLC), the type of technique (IMRT and VMAT), and the sophisticated grades of each technique (5-field, 9-field, 13-field, 17-field technique in IMRT and 1-arc and 2-arc techniques in VMAT). The downsizing effects of MLC leaf width were analyzed using target volume coverage (TVC), conformity index (CI), dose gradient index (GI), and normal tissue difference 70% isodose line and 50% isodose line. Upon replacing the 5-mm MLC with the 2.5-mm MLC, TVC and CI improved by 1.30% and 1.36%, respectively, in total plans. The TVC and CI improved by 1.68% and 1.67% in IMRT, respectively, and by 0.54% and 0.72% in VMAT, respectively. TVC improved by 2.53%, 1.82%, 1.34%, and 0.94%, and CI also improved by 2.70%, 1.81%, 1.24%, and 0.94%, in 5-field, 9-field, 13-field, and 17-field IMRT, respectively. TVC improved by 0.66% and 0.43%, and CI also improved by 0.93%, and 0.52% in 1-arc and 2-arc VMAT, respectively. Regarding the target coverage, there were dosimetric benefits of a smaller MLC leaf width. However, the downsizing effect of the MLC leaf width decreased with the use of a more precise RT technique and a more sophisticated grade of the same technique.

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“…Both the studies raised important questions regarding the significance of small dosimetric benefit with 2.5 mm MLC over 5 mm MLC. Recently, Chae et al (21) studied the effect of MLC width on radiosurgery planning for spine lesion treatments using the IMRT and VMAT techniques. They concluded that, although smaller (2.5 mm) MLC leaf width provides improved target coverage, the effect of MLC width seems to be more in IMRT than in VMAT.…”

Section: Discussionmentioning

confidence: 99%

“…In terms of normal tissue toxicity, except for 2.39 cc, both MLC plans satisfied the RTOG criteria for high and low dose spillage. Chae et al (21) showed that, for smaller and complex target volumes, the gradient index (GI) was less statistically significant with IMRT whereas the difference was marginal with VMAT. We also found similar results with the high dose and low dose spillage, and the average 2.39 cc target volume for HDMLC plans were found to be marginally better than the 5 mm MMLC plans.…”

Section: Discussionmentioning

confidence: 99%

Is 5 mm MMLC suitable for VMAT‐based lung SBRT? A dosimetric comparison with 2.5 mm HDMLC using RTOG‐0813 treatment planning criteria for both conventional and high‐dose flattening filter‐free photon beams

Subramanian

Subramani

Swamy

et al. 2015

J Applied Clin Med Phys

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The aim of this study is to assess the suitability of 5 mm millennium multileaf collimator (MMLC) for volumetric‐modulated arc therapy (VMAT)‐based lung stereotactic body radiotherapy (SBRT). Thirty lung SBRT patient treatment plans along with their planning target volumes (ranging from 2.01 cc to 150.11 cc) were transferred to an inhomogeneous lung phantom and retrospectively planned using VMAT technique, along with the high definition multileaf collimator (HDMLC) and MMLC systems. The plans were evaluated using Radiation Therapy Oncology Group (RTOG‐0813) treatment planning criteria for target coverage, normal tissue sparing, and treatment efficiency for both the MMLC and HDMLC systems using flat and flattening filter‐free (FFF) photon beams. Irrespective of the target volumes, both the MLC systems were able to satisfy the RTOG‐0813 treatment planning criteria without having any major deviation. Dose conformity was marginally better with HDMLC. The average conformity index (CI) value was found to be 1.069±0.034 and 1.075±0.0380 for HDMLC and MMLC plans, respectively. For the 6 MV FFF beams, the plan was slightly more conformal, with the average CI values of 1.063±0.029 and 1.073±0.033 for the HDMLC and MMLC plans, respectively. The high dose spillage was the maximum for 2 cc volume set (3% for HDMLC and 3.1% for MMLC). In the case of low dose spillage, both the MLCs were within the protocol of no deviation, except for the 2 cc volume set. The results from this study revealed that VMAT‐based lung SBRT using 5 mm MMLC satisfies the RTOG‐0813 treatment planning criteria for the studied target size and shapes.PACS numbers: 87.53.Ly, 87.53D, 87.56.jk

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The effect of multileaf collimator leaf width on the radiosurgery planning for spine lesion treatment in terms of the modulated techniques and target complexity

Cited by 27 publications

References 42 publications

The impact of a high‐definition multileaf collimator for spine SBRT

The impact of a high‐definition multileaf collimator for spine SBRT

Dosimetric impact of multileaf collimator leaf width according to sophisticated grade of technique in the IMRT and VMAT planning for pituitary adenoma lesion

Is 5 mm MMLC suitable for VMAT‐based lung SBRT? A dosimetric comparison with 2.5 mm HDMLC using RTOG‐0813 treatment planning criteria for both conventional and high‐dose flattening filter‐free photon beams

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