Comparison of Plan Quality and Delivery Time Between Volumetric Arc Therapy (RapidArc) and Gamma Knife Radiosurgery for Multiple Cranial Metastases

Thomas, Evan M.; Popple, Richard A.; Wu, X; Clark, Grant M.; Markert, James M.; Guthrie, Barton L.; Yuan, Ya; Dobelbower, M.C.; Spencer, Sharon A.; Fiveash, John B.

doi:10.1227/neu.0000000000000448

Cited by 162 publications

(186 citation statements)

References 27 publications

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“…[15][16][17] Although the selected cases in the present article were challenging by design, as shown in Table 3, we found reasonable agreement with other published data reported on radiation therapy delivery to multiple targets. 1,2,15,16,18 As seen in Table 3, the literature results generally fell within or very close to the 95% prediction band based on the model presented in Figure 3.…”

Section: Discussionsupporting

confidence: 90%

Investigation of two linear accelerator head designs for treating brain metastases with hypofractionated volumetric-modulated arc radiotherapy

Ruschin

Sahgal

Iradji

et al. 2016

BJR

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Objective: To investigate brain radiation dose in complex cases arising from two stereotactic linear accelerator designs and to present a method for comparing brain dose to published data. Methods: Two head designs were considered: Beam Modulator (BM) and Agility (AG). 12 patients treated on BM were replanned with AG. Planning objectives were: minimize brain dose and satisfy target coverage and organs at risk dose constraints. Each of the 36 targets was analyzed for conformality index (CI Paddick), gradient index (GI) and homogeneity index (HI). Total volume of tissue receiving 80% (V80) of the prescription dose down to 25% (V25) was evaluated. Similarly the volume of brain minus planning target volume receiving 80% (BMP80) down to 25% (BMP25) was evaluated. The mean brain dose and BMP dose were also evaluated. System differences were statistically evaluated using Wilcoxon signed-rank test. Powerlaw models for total volume (V) and brain minus planning target volumes (BMP) were generated based on BM data.Results: The median CI Paddick was 0.74 and 0.76 for BM and AG, respectively (p 5 0.04). The median GI was 5.5 and 6.1 (p , 0.01) and the median HI was 1.17 and 1.16 for BM and AG, respectively (p , 0.01). Neither V or BMP receiving doses of 80% down to 40% exhibited statistically significant difference between the two systems, whereas the volume of brain minus PTV receiving 25% (BMP25) was weakly different (p 5 0.02). AG exhibited a lower mean BMP dose (4.1 Gy) than BM (4.6 Gy) (p , 0.01). Power-law models for V/BMP showed excellent (R 2 . 0.80) agreement for the dose levels studied and comparable results with published data. Conclusion: Treatment plans of equivalent quality were attained with AG compared with BM. Advances in knowledge: The AG system involves a novel collimation design. The present article demonstrates equivalent or improved brain dose for complex, multitarget cases using AG vs an older stereotactic system. INTRODUCTIONThe use of intensity-modulated radiotherapy or volumetricmodulated arc radiotherapy (VMAT) using multileaf collimators (MLCs) for stereotactic radiosurgery and radiotherapy is becoming increasingly popular, as this technique affords efficient delivery with a high degree of target conformality. [1][2][3] In particular, for multiple targets, the use of VMAT has been implicated in yielding shorter treatment times while providing comparable plan quality to intensity-modulated radiotherapy and three-dimensional conformal treatments. 1 Initial experiences with VMAT were with multi-isocentre plans, 4,5 followed by a series of studies investigating the feasibility of a singleisocentre approach. 2,6

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Section: Discussionsupporting

confidence: 90%

Investigation of two linear accelerator head designs for treating brain metastases with hypofractionated volumetric-modulated arc radiotherapy

Ruschin

Sahgal

Iradji

et al. 2016

BJR

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“…Thomas et al. reported results for cases with 2–9 lesions and total tumor volumes from 0.23–19.56 cm 3 , all planned with 18 Gy prescriptions 4. Our preclinical cases had 2–8 lesions with a total tumor volume ranging from 1.09 to 26.95 cm 3 and most of the lesions were prescribed 21 Gy.…”

Section: Discussionmentioning

confidence: 75%

“…One study reported that VMAT plans provide superior conformity with no significant difference in dose fall off compared to Gamma Knife plans,4 whereas another study found that VMAT plans had comparable conformity to Gamma Knife but that Gamma Knife remained superior in terms of dose fall off around the target 9. Liu et al.…”

Section: Discussionmentioning

confidence: 99%

“…Recent publications have reported on VMAT planning for cranial SRS patients with multiple lesions using one isocenter and demonstrated that highly conformal dose distributions can be achieved 1, 2. Plan parameters have been compared to Gamma Knife plans which are considered the standard for cranial SRS treatment 3, 4. These studies have shown that VMAT plans can produce target coverage and dose fall‐off in the high dose area similar to Gamma Knife plans.…”

Section: Introductionmentioning

confidence: 99%

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Institutional experience with SRS VMAT planning for multiple cranial metastases

Ballangrud

Kuo

Happersett

et al. 2018

J Applied Clin Med Phys

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Background and PurposeThis study summarizes the cranial stereotactic radiosurgery (SRS) volumetric modulated arc therapy (VMAT) procedure at our institution.Materials and MethodsVolumetric modulated arc therapy plans were generated for 40 patients with 188 lesions (range 2–8, median 5) in Eclipse and treated on a TrueBeam STx. Limitations of the custom beam model outside the central 2.5 mm leaves necessitated more than one isocenter pending the spatial distribution of lesions. Two to nine arcs were used per isocenter. Conformity index (CI), gradient index (GI) and target dose heterogeneity index (HI) were determined for each lesion. Dose to critical structures and treatment times are reported.ResultsLesion size ranged 0.05–17.74 cm3 (median 0.77 cm3), and total tumor volume per case ranged 1.09–26.95 cm3 (median 7.11 cm3). For each lesion, HI ranged 1.2–1.5 (median 1.3), CI ranged 1.0–2.9 (median 1.2), and GI ranged 2.5–8.4 (median 4.4). By correlating GI to PTV volume a predicted GI = 4/PTV0.2 was determined and implemented in a script in Eclipse and used for plan evaluation. Brain volume receiving 7 Gy (V 7 Gy) ranged 10–136 cm3 (median 42 cm3). Total treatment time ranged 24–138 min (median 61 min).ConclusionsVolumetric modulated arc therapy provide plans with steep dose gradients around the targets and low dose to critical structures, and VMAT treatment is delivered in a shorter time than conventional methods using one isocenter per lesion. To further improve VMAT planning for multiple cranial metastases, better tools to shorten planning time are needed. The most significant improvement would come from better dose modeling in Eclipse, possibly by allowing for customizing the dynamic leaf gap (DLG) for a special SRS model and not limit to one DLG per energy per treatment machine and thereby remove the limitation on the Y‐jaw and allow planning with a single isocenter.

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“…Therefore, some studies have proposed treating multiple metastases with a single setup isocenter using volumetric modulated arc therapy (VMAT) technique 6 , 7 , 8 , 9 . However, the quality assurance and plan‐specific dose verification of a single‐isocenter multimetastases VMAT plan is a challenge to clinical physicists, due to the nature of small target volumes and low resolution detector arrays.…”

Section: Introductionmentioning

confidence: 99%

Dosimetric validation for an automatic brain metastases planning software using single‐isocenter dynamic conformal arcs

Liu

Pappas

et al. 2016

J Applied Clin Med Phys

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An automatic brain‐metastases planning (ABMP) software has been installed in our institution. It is dedicated for treating multiple brain metastases with radiosurgery on linear accelerators (linacs) using a single‐setup isocenter with noncoplanar dynamic conformal arcs. This study is to validate the calculated absolute dose and dose distribution of ABMP. Three types of measurements were performed to validate the planning software: 1, dual micro ion chambers were used with an acrylic phantom to measure the absolute dose; 2, a 3D cylindrical phantom with dual diode array was used to evaluate 2D dose distribution and point dose for smaller targets; and 3, a 3D pseudo‐in vivo patient‐specific phantom filled with polymer gels was used to evaluate the accuracy of 3D dose distribution and radiation delivery. Micro chamber measurement of two targets (volumes of 1.2 cc and 0.9 cc, respectively) showed that the percentage differences of the absolute dose at both targets were less than 1%. Averaged GI passing rate of five different plans measured with the diode array phantom was above 98%, using criteria of 3% dose difference, 1 mm distance to agreement (DTA), and 10% low‐dose threshold. 3D gel phantom measurement results demonstrated a 3D displacement of nine targets of 0.7±0.4 mm (range 0.2 ~ 1.1 mm). The averaged two‐dimensional (2D) GI passing rate for several region of interests (ROI) on axial slices that encompass each one of the nine targets was above 98% (5% dose difference, 2 mm DTA, and 10% low‐dose threshold). Measured normalD95, the minimum dose that covers 95% of the target volume, of the nine targets was 0.7% less than the calculated normalD95. Three different types of dosimetric verification methods were used and proved the dose calculation of the new automatic brain metastases planning (ABMP) software was clinical acceptable. The 3D pseudo‐in vivo patient‐specific gel phantom test also served as an end‐to‐end test for validating not only the dose calculation, but the treatment delivery accuracy as well.PACS number(s): 87.53.Lv, 87.55.km, 87.55.Qr

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Comparison of Plan Quality and Delivery Time Between Volumetric Arc Therapy (RapidArc) and Gamma Knife Radiosurgery for Multiple Cranial Metastases

Cited by 162 publications

References 27 publications

Investigation of two linear accelerator head designs for treating brain metastases with hypofractionated volumetric-modulated arc radiotherapy

Investigation of two linear accelerator head designs for treating brain metastases with hypofractionated volumetric-modulated arc radiotherapy

Institutional experience with SRS VMAT planning for multiple cranial metastases

Dosimetric validation for an automatic brain metastases planning software using single‐isocenter dynamic conformal arcs

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