Plan optimization for mediastinal radiotherapy: Estimation of coronary arteries motion with ECG-gated cardiac imaging and creation of compensatory expansion margins

Levis, Mario; Luca, V. De; Fiandra, C.; Veglia, Simona; Fava, Antonella; Gatti, Marco; Giorgi, Mauro; Bartoncini, Sara; Cadoni, Federica; Garabello, Domenica; Ragona, Riccardo; Filippi, Andrea Riccardo; Ricardi, Umberto

doi:10.1016/j.radonc.2018.04.014

Cited by 27 publications

(24 citation statements)

References 31 publications

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“…Different from the breathing motion, cardiac motion is fast and asymmetrical. [11][12][13] The motion magnitude of each substructure of the heart varies in the rapid cycle of heart beat. Typical CT scanners used in radiation oncology departments are not suitable for study of the cardiac motion.…”

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confidence: 99%

Analysis of cardiac motion without respiratory motion for cardiac stereotactic body radiation therapy

Ouyang

Schoenhagen

Wazni

et al. 2020

J Applied Clin Med Phys

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Purpose/objective(s) To study the heart motion using cardiac gated computed tomographies (CGCT) to provide guidance on treatment planning margins during cardiac stereotactic body radiation therapy (SBRT). Materials/methods Ten patients were selected for this study, who received CGCT scans that were acquired with intravenous contrast under a voluntary breath‐hold using a dual source CT scanner. For each patient, CGCT images were reconstructed in multiple phases (10%–90%) of the cardiac cycle and the left ventricle (LV), right ventricle (RV), ascending aorta (AAo), ostia of the right coronary artery (O‐RCA), left coronary artery (O‐LCA), and left anterior descending artery (LAD) were contoured at each phase. For these contours, the centroid displacements from their corresponding average positions were measured at each phase in the superior–inferior (SI), medial–lateral (ML), and anterior–posterior (AP). The average volumes as well as the maximum to minimum ratios were analyzed for the LV and RV. Results For the six contoured substructures, more than 90% of the measured displacements were <5 mm. For these patients, the average volumes ranged from 191.25 to 429.51 cc for LV and from 91.76 to 286.88 cc for RV. For each patient, the ratios of maximum to minimum volumes within a cardiac cycle ranged from 1.15 to 1.54 for LV and from 1.34 to 1.84 for RV. Conclusion Based on this study, cardiac motion is variable depending on the specific substructure of the heart but is mostly within 5 mm. Depending on the location (central or peripheral) of the treatment target and treatment purposes, the treatment planning margins for targets and risk volumes should be adjusted accordingly. In the future, we will further assess heart motion and its dosimetric impact.

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confidence: 99%

Analysis of cardiac motion without respiratory motion for cardiac stereotactic body radiation therapy

Ouyang

Schoenhagen

Wazni

et al. 2020

J Applied Clin Med Phys

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“…It has been shown that even under breath-hold conditions, cardiac substructures may displace~5 to 7 mm throughout the cardiac cycle. 38,39 Thus, incorporating a planning organ at risk volume (PRV) representing the variability of the cardiac substructures over a patient's imaging and treatment course will be the next step of this work. However, as substructure PRV recommendations do not currently exist for each substructure and this study was unable to account for cardiac motion, they were beyond the scope of the current work.…”

Section: Discussionmentioning

confidence: 99%

Incorporating sensitive cardiac substructure sparing into radiation therapy planning

Morris

Aldridge²,

Ghanem

et al. 2020

J Applied Clin Med Phys

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Purpose: Rising evidence suggests that cardiac substructures are highly radiosensitive. However, they are not routinely considered in treatment planning as they are not readily visualized on treatment planning CTs (TPCTs). This work integrated the soft tissue contrast provided by low-field MRIs acquired on an MR-linac via image registration to further enable cardiac substructure sparing on TPCTs. Methods: Sixteen upper thoracic patients treated at various breathing states (7 end-exhalation, 7 end-inhalation, 2 free-breathing) on a 0.35T MR-linac were retrospectively evaluated. A hybrid MR/CT atlas and a deep learning three-dimensional (3D) U-Net propagated 13 substructures to TPCTs. Radiation oncologists revised contours using registered MRIs. Clinical treatment plans were re-optimized and evaluated for beam arrangement modifications to reduce substructure doses. Dosimetric assessment included mean and maximum (0.03cc) dose, left ventricular volume receiving 5Gy (LV-V5), and other clinical endpoints. As metrics of plan complexity, total MU and treatment time were evaluated between approaches. Results: Cardiac sparing plans reduced the mean heart dose (mean reduction 0.7 ± 0.6, range 0.1 to 2.5 Gy). Re-optimized plans reduced left anterior descending artery (LADA) mean and LADA 0.03cc (0.0-63.9% and 0.0-17.3 Gy, respectively). LV 0.03cc was reduced by >1.5 Gy for 10 patients while 6 cases had large reductions (>7%) in LV-V5. Left atrial mean dose was equivalent/reduced in all sparing plans (mean reduction 0.9 ± 1.2 Gy). The left main coronary artery was better spared in all cases for mean dose and D 0.03cc. One patient exhibited >10 Gy reduction in D 0.03cc to four substructures. There was no statistical difference in treatment time and MU, or clinical endpoints to the planning target volume, lung, esophagus, or spinal cord after re-optimization. Four patients benefited from new beam arrangements, leading to further dose reductions. Conclusions: By introducing 0.35T MRIs acquired on an MR-linac to verify cardiac substructure segmentations for CT-based treatment planning, an opportunity was presented for more effective sparing with limited increase in plan complexity. Validation in a larger cohort with appropriate margins offers potential to reduce radiation-related cardiotoxicities.

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“…The influence on the robustness of the proton plans is therefore not just applicable to other planning specifications (other spot size, etc.). Lastly, the influence of the cardiac motion on the robustness of a proton plan could be more relevant at the level of a cardiac substructure, such as the circumflex artery [28].…”

Section: Discussionmentioning

confidence: 99%

A study to investigate the influence of cardiac motion on the robustness of pencil beam scanning proton plans in oesophageal cancer

Thomas

Defraene

Levis

et al. 2020

Physics and Imaging in Radiation Oncology

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Plan optimization for mediastinal radiotherapy: Estimation of coronary arteries motion with ECG-gated cardiac imaging and creation of compensatory expansion margins

Cited by 27 publications

References 31 publications

Analysis of cardiac motion without respiratory motion for cardiac stereotactic body radiation therapy

Analysis of cardiac motion without respiratory motion for cardiac stereotactic body radiation therapy

Incorporating sensitive cardiac substructure sparing into radiation therapy planning

A study to investigate the influence of cardiac motion on the robustness of pencil beam scanning proton plans in oesophageal cancer

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