EP-1837: Characterization of VMAT plan complexity

Lønne, P.; Waldeland, E.; Hellebust, Taran Paulsen; Hoven, N.I.

doi:10.1016/s0167-8140(18)32146-7

Cited by 1 publication

(3 citation statements)

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“…Some authors have reported correlations between dosimetric accuracy and various plan complexity metrics, while others did not find such correlation . In the current study, we investigated possible correlations between measured motion‐induced dose deviations and plan complexity metrics for highly hypofractionated SBRT lung plans as well as normofractionated lung radiotherapy plans.…”

Section: Discussionmentioning

confidence: 99%

“…Possible correlations between measured dose deviations and the modulation complexity score applied to VMAT (MCSv), MLC leaf travel (LT), the average change in dose rate per control point (ΔDR/cp), monitor units pr. Gy (MU/Gy), and homogeneity index for the PTV (HI) were investigated . A lower MCSv indicates a plan with more modulation, while a MCSv of 1 indicates no modulation, that is, a static, open field.…”

Section: Methodsmentioning

confidence: 99%

“…Various authors have investigated possible correlations between plan complexity metrics and dosimetric accuracy . Various measuring devices, delivery techniques, and complexity metrics were used.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Dose deviations induced by respiratory motion for radiotherapy of lung tumors: Impact of CT reconstruction, plan complexity, and fraction size

Sande

Roa

Hellebust

2020

J Applied Clin Med Phys

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A thorax phantom was used to assess radiotherapy dose deviations induced by respiratory motion of the target volume. Both intensity modulated and static, non-modulated treatment plans were planned on CT scans of the phantom. The plans were optimized using various CT reconstructions, to investigate whether they had an impact on robustness to target motion during delivery. During irradiation, the target was programmed to simulate respiration-induced motion of a lung tumor, using both patient-specific and sinusoidal motion patterns in three dimensions. Dose was measured in the center of the target using an ion chamber. Differences between reference measurements with a stationary target and dynamic measurements were assessed. Possible correlations between plan complexity metrics and measured dose deviations were investigated. The maximum observed motion-induced dose differences were 7.8% and 4.5% for single 2 Gy and 15 Gy fractions, respectively. The measurements performed with the largest target motion amplitude in the superiorinferior direction yielded the largest dosimetric deviations. For 2 Gy fractionation schemes, the summed dose deviation after 33 fractions is likely to be less than 2%.Measured motion-induced dose deviations were significantly larger for one CT reconstruction compared to all the others. Static, non-modulated plans showed superior robustness to target motion during delivery. Moderate correlations between the modulation complexity score applied to VMAT (MCSv) and measured dose deviations were found for 15 Gy SBRT treatment plans. Correlations between other plan complexity metrics and measured dose deviations were not found. K E Y W O R D S complexity, interplay, lung, radiotherapy, SBRT, VMAT

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%