Geometrical and dosimetrical uncertainties in hypofractionated radiotherapy of the lung: A review

Schwarz, Marco; Cattaneo, Giovanni Mauro; Marrazzo, L.

doi:10.1016/j.ejmp.2017.02.011

Cited by 54 publications

(62 citation statements)

References 132 publications

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“…These findings are consistent with observations described in literature. 4,9,51,52 The PTV 80s r , as the most conservative PMM approach investigated in this study, yielded the highest SE values at the largest PTV volumes that might be unacceptably large for clinical application.…”

Section: Discussionmentioning

confidence: 86%

Real‐time 4DMRI‐based internal target volume definition for moving lung tumors

et al. 2020

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PTVs were smaller than the ITV-based PTVs. While the SE was high for patients with small breathing pattern variations, changes of the median breathing amplitudes in different imaging sessions led to inferior SE values for the mid-ventilation PTV for one patient. In contrast, PTV 5% r and PTV 10% r showed higher SE values with a higher robustness against interfractional changes, at the cost of larger target volumes. Conclusions:The results indicate that rt-4DMRI could be valuable for the definition of target volumes based on the GTV POP to achieve a higher robustness against interfractional changes than feasible with today's 4D-CT-based target definition concepts.

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Section: Discussionmentioning

confidence: 86%

Real‐time 4DMRI‐based internal target volume definition for moving lung tumors

et al. 2020

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“…Dose delivery with VMAT technique (where the dose modulation is obtained by the variation of leaves position and speed, gantry angle and speed, and dose rate) on moving targets could be affected by the so-called interplay effect, which is caused by the interaction between dose delivery and anatomy movement. 27 The quantification of the interplay effect in lung SBRT has been the subject of several papers, that demonstrated the interplay effect to be generally small, even for highly modulated intensity patterns. 27 Nevertheless, with large motion and increased motion period 28 or for respiratory curves exhibiting irregular breathing patterns 29 the interplay effect may become significant, which supports the choice of a moderate modulation.…”

Section: C | Dose Distribution Comparisonmentioning

confidence: 99%

Automated planning through robust templates and multicriterial optimization for lung VMAT SBRT of lung lesions

Marrazzo

Arilli

Pellegrini

et al. 2020

J Applied Clin Med Phys

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Purpose: To develop and validate a robust template for VMAT SBRT of lung lesions, using the multicriterial optimization (MCO) of a commercial treatment planning system. Methods: The template was established and refined on 10 lung SBRT patients planned for 55 Gy/5 fr. To improve gradient and conformity a ring structure around the planning target volume (PTV) was set in the list of objectives. Ideal fluence optimization was conducted giving priority to organs at risk (OARs) and using the MCO, which further pushes OARs doses. Segmentation was conducted giving priority to PTV coverage. Two different templates were produced with different degrees of modulation, by setting the Fluence Smoothing parameter to Medium (MFS) and High (HFS). Each template was applied on 20 further patients. Automatic and manual plans were compared in terms of dosimetric parameters, delivery time, and complexity. Statistical significance of differences was evaluated using paired two-sided Wilcoxon signed-rank test. Results: No statistically significant differences in PTV coverage and maximum dose were observed, while an improvement was observed in gradient and conformity. A general improvement in dose to OARs was seen, which resulted to be significant for chest wall V 30 Gy , total lung V 20 Gy , and spinal cord D 0.1 cc. MFS plans are characterized by a higher modulation and longer delivery time than manual plans. HFS plans have a modulation and a delivery time comparable to manual plans, but still present an advantage in terms of gradient. Conclusion: The automation of the planning process for lung SBRT using robust templates and MCO was demonstrated to be feasible and more efficient.

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“…Dosimetric deviations due to intra‐fractional motion of the target volume should be divided into blurring effects and interplay effects , as described by several authors . The blurring effect will occur both for static 3D conformal radiotherapy (CRT) fields and for modulated treatment fields, and may be understood as a “smearing out” of the (more or less) inhomogeneous static dose distribution seen in the treatment planning system (TPS), due to motion.…”

Section: Introductionmentioning

confidence: 99%

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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Geometrical and dosimetrical uncertainties in hypofractionated radiotherapy of the lung: A review

Cited by 54 publications

References 132 publications

Real‐time 4DMRI‐based internal target volume definition for moving lung tumors

Real‐time 4DMRI‐based internal target volume definition for moving lung tumors

Automated planning through robust templates and multicriterial optimization for lung VMAT SBRT of lung lesions

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

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