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

Abstract

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.

Stereotactic body radioablation therapy as an immediate and early term antiarrhythmic palliative therapeutic choice in patients with refractory ventricular tachycardia

“…The long-term safety of this treatment is not known, and only extrapolations from long-term data from the cancer population might be applied at this time. The noninvasive computed tomography (CT)-based surface electrocardiographic imaging has been proposed in initial reports [ 2 , 17 ]; however, the availability of ECGI remains limited outside of select institutions and countries ( 28 ). Therefore, we used this new modality with the guidance of imaging techniques (such as CT, positron emission tomography, cardiac magnetic resonance imaging) integrated by three-dimensional electro-anatomic mapping (EAM) data in the absence of the ECGI.…”

“…Respiratory and cardiac motions have to be incorporated into treatment planning to ensure accurate dose delivery to the target region [ 15 ], either through adequate range-considering internal margins or through more conformal strategies such as ECG-based gating or even 4D optimization [ 16 ]. 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 [ 17 ]. In this trial, we gave an additional internal margin around the GTV rather than ECG-Gating and 4D optimization to ensure accurate dose delivery to the target for uncertainties that caused by cardiac and respiratory motion as assessed by review of the 4D-CT [ 6 , 13 ] 3, 10 .…”

Validation of an established deep learning auto-segmentation tool for cardiac substructures in 4D radiotherapy planning scans

“…Furthermore, substructure motion will not necessarily be oscillatory after interactions from concurrent respiratory motion are considered. With gold standard cardiac-gated CT in breath-hold, where lung motion was obviated, centroid shifts for select substructures were limited to 0.5–1.6 mm [48] .…”

Role of Real-World Data in Assessing Cardiac Toxicity After Lung Cancer Radiotherapy

“…Another avenue that some authors have pursued is to use motion compensation to improve the quality of planning CTs and reduce contour uncertainties. Even though the motion of heart sub-structures due to heartbeat is reportedly small (typically <5 mm) ( 84 ), the heart can move 5-20 mm due to respiration. With the adoption of 4DCT worldwide, the use of different reconstruction techniques may add uncertainty to heart sub-structure segmentation.…”