Comparison of treatment plan quality of VMAT for esophageal carcinoma with: flattening filter beam versus flattening filter free beam

Sun, Wen Zhao; Chen, li; Yang, Xin; Wang, Bin; Deng, Xiao Wu; Huang, Xiao Yan

doi:10.7150/jca.26044

Cited by 11 publications

(12 citation statements)

References 23 publications

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“…Because the FFF mode requires more MUs for a point in a segment far away from the central axis to achieve the same depth dose as the point in the central, the average total MUs for FFF‐VMAT plans was greater than that of the FF‐VMAT plans. This finding is in line with the results from previous studies 19,25,26 . However, there was no significant difference observed in the plan quality among the two beam modes.…”

Section: Discussionsupporting

confidence: 92%

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Comparison between flattening filter‐free (FFF) and flattened photon beam VMAT plans for the whole brain radiotherapy (WBRT) with hippocampus sparing

Sun

Cai

et al. 2021

Asia-Pac J Clncl Oncology

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Purpose To evaluate and investigate the feasibility of flattening filter‐free (FFF) beam for the whole‐brain radiotherapy (WBRT) with hippocampus sparing. Methods Eighteen patients with volumetric‐modulated arc therapy (VMAT) plans in FFF and conventional beam modes were included in this study. The prescribed dose was 30 Gy in 10 fractions. The conformity index (CI), heterogeneity index reported by TPS (HI‐M), and homogeneity index (HI) for planning target volume (PTV) were evaluated. Subsequently, the following parameters for PTV were calculated and compared: D2%, D98%; the mean dose, maximum dose, and minimal dose for OARs. Plan modulation index, total MUs, and the gamma index were used to evaluate the plan quality. Results HI‐M results were similar for the two techniques (1.239 vs. 1.247, respectively, p = 0.048); FFF beam plans yielded lower D2% compared to FF beam plans (3,416.3 cGy vs. 3,437.2 cGy, p = 0.22), mean dose (3,177.5 cGy vs. 3,195.2 cGy, p = 0.009), and CI (0.884 vs. 0.876, p = 0.001) for PTV. Significant differences were observed between the two beam modes (FF model vs. FFF model) for the maximum dose (1,612.9 cGy vs. 1,470.2 cGy, respectively, p < 0.001), minimum dose (987.6 cGy vs. 898.8 cGy, respectively, p < 0.001), and the mean dose (1144.4 cGy vs. 1047.3 cGy, respectively, p < 0.001) to the hippocampus, and the maximum dose to the eyes (2,792.6 cGy vs. 2,751.3 cGy, respectively, p < 0.001). The average total MUs for FFF‐VMAT plans was significantly greater than FF‐VMAT plans. However, differences for the plan modulation index and the gamma index were negligible. Conclusion In comparison with FF beam, the FFF beam mode offers a clear benefit with respect to WBRT with hippocampal sparing.

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Section: Discussionsupporting

confidence: 92%

“…This finding is in line with the results from previous studies. 19,25,26 However, there was no significant difference observed in the plan quality among the two beam modes.…”

Section: Discussionmentioning

confidence: 85%

Comparison between flattening filter‐free (FFF) and flattened photon beam VMAT plans for the whole brain radiotherapy (WBRT) with hippocampus sparing

Sun

Cai

et al. 2021

Asia-Pac J Clncl Oncology

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“…The maximum dose and near max dose to the PTV was higher in the FFF mode but the mean dose was less in comparison with the FF mode which was found by many authors like Sun et al 24 Our study showed that the treatment planning with FFF beams resulted in plans of equal quality in terms of PTV coverage compared with flattened beams. No significant differences were found in dose coverage for PTV in both plans.…”

Section: Discussionsupporting

confidence: 71%

Dosimetric impact of FFF over FF beam using VMAT for brain neoplasms treated with radiotherapy

Manna

Kombathula

Gayen

et al. 2021

Polish Journal of Medical Physics and Engineering

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Background: This study was conducted to assess the dosimetric impact of FFF beam plans on high-grade brain neoplasms using the VMAT technique when compared with FF beam plans. Material and Methods: Thirty patients with high-grade brain neoplasms, who had received radiotherapy using VMAT technique retrospectively were selected for this study. All the patients were planned for VMAT using 6MV_FF beam and the same plan was re-optimized using 6MV_FFF beam keeping the same dose constraint. Radiotherapy dose distribution on planning target volume (PTV) and organs at risk (OAR), target conformity index (CI), Homogeneity Index (HI), Low dose volume in the patient (V5, V10, V20, and V30), and Integral dose to the whole body in both plans were compared. Results: The PTV coverage and OAR’s showed no significant differences in dose distribution between the FFF and FF beam VMAT planning. There was a reduction of the average maximum dose in the right eye, left eye, right optic nerve, and left optic nerve using FFF beams. The reduction in average low dose volume was observed in V5, V10, V20, V30, and Mean Dose. Also, a significant reduction was observed in the integral dose to the whole body using the FFF beam. Conclusions: Using FFF beams with VMAT is doable for the treatment of high-grade brain neoplasms, and the delivery mode of the FFF beam in VMAT may yield similar results to FF beam which should be confirmed in a large scale prospective clinical trial.

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“…The reduction of delivery time in the application of VMAT compared to IMRT was also found in the same order for other entities [12,18,49], using the same equipment. Most comparisons of FB and FFF in these studies and also [29] found shorter or statistically not significantly different DTs for FFF. Treutwein et al [18] discussed that additional MU are required to compensate the profile fall off which also takes additional time.…”

Section: Plan Qualitymentioning

confidence: 48%

“…It supports an improvement of the conformity. The same set of dose volume objectives has been used for all plans to get comparable results [12,18,28,29]. The aim of this set was to keep the risk for the OARs on an acceptable level, but to leave freedom for the optimizer to achieve good conformity and homogeneity.…”

Section: Treatment Planningmentioning

confidence: 99%

The influence of radiotherapy techniques on the plan quality and on the risk of secondary tumors in patients with pituitary adenoma

Treutwein¹,

Steger²,

Loeschel

et al. 2020

BMC Cancer

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Background: This planning study compares different radiotherapy techniques for patients with pituitary adenoma, including flatness filter free mode (FFF), concerning plan quality and secondary malignancies for potentially young patients. The flatness filter has been described as main source of photon scatter.Material and methods: Eleven patients with pituitary adenoma were included. An Elekta Synergy™ linac was used in the treatment planning system Oncentra® and for the measurements. 3D plans, IMRT, and VMAT plans and noncoplanar varieties were considered. The plan quality was evaluated regarding homogeneity, conformity, delivery time and dose to the organs at risk. The secondary malignancy risk was calculated from dose volume data and from measured dose to the periphery using different models for carcinoma and sarcoma risk.Results: The homogeneity and conformity were nearly unchanged with and without flattening filter, neither was the delivery time found substantively different. VMAT plans were more homogenous, conformal and faster in delivery than IMRT plans. The secondary cancer risk was reduced with FFF both in the treated region and in the periphery. VMAT plans resulted in a higher secondary brain cancer risk than IMRT plans, but the risk for secondary peripheral cancer was reduced. Secondary sarcoma risk plays a minor role. No advantage was found for non-coplanar techniques. The FFF delivery times were not shortened due to additional monitor units needed and technical limitations. The risk for secondary brain cancer seems to depend on the irradiated volume. Secondary sarcoma risk is much smaller than carcinoma risk in accordance to the results of the atomic bomb survivors. The reduction of the peripheral dose and resulting secondary malignancy risk for FFF is statistically significant. However, it is negligible in comparison to the risk in the treated region.Conclusion: Treatments with FFF can reduce secondary malignancy risk while retaining similar quality as with flattening filter and should be preferred. VMAT plans show the best plan quality combined with lowest peripheral secondary malignancy risk, but highest level of second brain cancer risk. Taking this into account VMAT FFF seems the most advantageous technique for the treatment of pituitary adenomas with the given equipment.

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Comparison of treatment plan quality of VMAT for esophageal carcinoma with: flattening filter beam versus flattening filter free beam

Cited by 11 publications

References 23 publications

Comparison between flattening filter‐free (FFF) and flattened photon beam VMAT plans for the whole brain radiotherapy (WBRT) with hippocampus sparing

Comparison between flattening filter‐free (FFF) and flattened photon beam VMAT plans for the whole brain radiotherapy (WBRT) with hippocampus sparing

Dosimetric impact of FFF over FF beam using VMAT for brain neoplasms treated with radiotherapy

The influence of radiotherapy techniques on the plan quality and on the risk of secondary tumors in patients with pituitary adenoma

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